Green Engine seminar report

1.   GLOBAL ISSUES

          Everyday radios, newspapers, televisions and the internet warn us of energy exhaustion, atmospheric pollution and hostile climatic conditions. After few hundred years of industrial development, we are facing these global problems while at the same time we maintain a high standard of living. The most important problem we are faced with is whether we should continue “developing” or “die”.

          Coal, petroleum, natural gas, water and nuclear energy are the five main energy sources that have played important roles and have been widely used by human beings.

          The United Nations Energy Organization names all of them “elementary energies”, as well as “conventional energies”. Electricity is merely a “second energy” derived from these sources. At present, the energy consumed all over the world almost completely relies on the supply of the five main energy sources. The consumption of petroleum constitutes approximately 60 percent of energy used from all sources, so it is the major consumer of energy.

          Statistics show that, the daily consumption of petroleum all over the world today is 40 million barrels, of which about 50 percent is for automobile use. That is to say, auto petroleum constitutes about 35 percent of the whole petroleum consumption. In accordance with this calculation, daily consumption of petroleum by automobiles all over the world is over two million tonnes. At the same time as these fuels are burnt, poisonous materials such as 500 million tonnes of carbon monoxides (CO), 100 million tonnes of hydrocarbons (HC), 550 million tonnes of carbon (C), 50 million tonnes of nitrogen oxides (NO_x) are emitted into the atmosphere every year, severely polluting the atmosphere. At the same time large quantities of carbon dioxide (CO₂) gases, resulting from burning, have also taken the major responsibility for the “green house effect”. Atmospheric scientists now believe that carbon dioxide is responsible for about half the total “green house effect”. Therefore, automobiles have to be deemed as the major energy consumer and atmosphere’s contaminator. Also, this situation is fast growing with more than 50 million vehicles to be produced annually all over the world and place into the market. However, at is estimate that petroleum reserve in the globe will last for only 38 years . The situation is really very grim.

          Addressing such problems is what a Green engine does or tries to do. The Green engine as it is named for the time being, is a six phase engine, which has a very low exhaust emission, higher efficiency, low vibrations etc. Apart from these features, is its uniqueness to adapt to any fuel which is also well burnt. Needless to say, if implemented will serve the purpose to a large extent.

2.   TECHNICAL FEATURES

          Compared to conventional piston engines, operated on four phases, the Green engine is an actual six phase internal combustion engine with much higher expansion ratio. Thus it has six independent or separate working processes: intake, compression, mixing, combustion, power and exhaust, resulting in the high air charge rate. Satisfactory air-fuel mixing, complete burning, high combustion efficiency and full expansion. The most important characteristic is the expansion ratio being much bigger than the compression ratio. Also, the other main features are the revolutionary innovations of the sequential variable compression ratio, constant volume combustion and self-adapting sealing system. Therefore, an engine having extremely high thermal efficiency, near-zero emissions, quietness, light and small, lower cost with capability of burning of various fuels has come into being.

2.1     Direct  Air Intake

Direct air intake means that there is no air inlet pipe, throttle and inlet valves on the air intake system. Air filter is directly connected to the intake port of the engine, and together with the less heating effect of air intake process, benefited from lower temperature of independent intake chamber, a highest volumetric efficiency which makes engine produce a high torque of output on all speed range is achieved . The pump loss which consumes the part of engine power is eliminated .Also fuel measuring  facilities are built-in,and parts are saved.

2.2 Strong Swirling 

          As a tangential air duct in between combustion chamber and compression chamber, a very swirling which could lost until gas port  is opened, can be formed while air is pumped into the combustion chamber. Consequently, the air-fuel mixing and the combustion process can have a satisfying working condition.

2.3 Sequential Variable Compression Ratio

          This greatly revolutionary innovation can provide the most suitable compression ratio for the engine whatever operation mode it works on with burning variety of fuels. Therefore, an excellent combustion performance is attained.

2.4 Direct Fuel Injection

          Direct fuel injection can provide higher output and torque, while at the same time it also enhances the response for acceleration.

2.5 Super Air-Fuel Mixing

          Since the independent air-fuel mixing phase is having enough time for mixing air and fuel under strong swirling and hot situation, the engine is capable to burn any liquid or gas fuels without modifications. An ideal air-fuel mixture could delete CO emission. Also centrifugal effect coming from both strong swirling and rotation of the burner makes the air-fuel mixture more dense near the spark plug. It benefits to cold starting and managing lean-burning.

2.6 Lowest Surface to Volume Ratio

          The shape of combustion chamber herein can be designed as global as possible. Thus, a lowest surface to is obtained, and the engine is having less heat losses and high combustion efficiency.

2.7 Controllable Combustion Time

          Due to the independent combustion phase, compared to the conventional engine whose performances lack of efficient combustion time, resulting in heavy CO emission and low fuel usage rate, the Green engine has a sufficient controllable combustion time to match any fuels.

2.8 Constant Volume Combustion

          The fuels can generate more energy while the combustion occurs on the constant volume. Also, the constant volume combustion technology can allow the engine to have a stable combustion when the lean burning is managed. Moreover, more water can be added in to make the much higher working pressure and drop down the combustion temperature, so power is added; heat losses and NO_x emissions are decreased.

2.9 Multi-Power Pulses

          The green engine operates on multi-power pulses with a small volume of working chamber contrasted to the conventional engine dose on the single power pulse with a large working chamber. Obviously, a small volume of chamber only needs little space, resulting in compact structure and limited size. Also, a small amount of air-fuel mixtures being ignited on each power pulse can greatly cut down explosion noise.

2.10 High Working Temperature

          Because the burner, which is made of high heat resistance and low expansion rate material, such as ceramic, operates without cooling, a relatively high working temperature can eliminate the quenching zone which is the main source of emission and can greatly reduce the heat losses in the combustion chamber.

2.11 High Expansion Ratio

          High expansion ratio can make the burnt gases to release much more power. In other words, the waste gases while they run out of the engine are only bringing much less energy with them. Therefore, the engine’s thermal efficiency is greatly raised, and at the same time, the noise and temperature of the exhaust are tremendously dropped.

2.12 Self-Adapting Sealing System

          This is another revolutionary innovation applied in the Green engine: it can eliminate a number of seal plates or strips to achieve gapless seal and to provide most efficient and reliable sealing system with less friction.

2.13 Vibration Free

          As major moving parts, vanes which are counted in little mass and operated symmetrically, the performance of the engine is very smooth. Hence, vibrations are eliminated.

2.14 Modular Design

          Use of modular design is the best way for engine mass production. Thus stacking of rotors easily extends range of available power.

2.15 Limited Parts and Small Size

          There is only a few dozens of parts which can be easily manufactured in the engine structure when compared with modern piston engine which comprises of more than a thousand parts. It suggests that the cost will be very low. Also, due to the compact structure the package and the weight of the Green engine will be only 1/5 to 1/10 of the regular engine on the same output.

3.         CONSTRUCTION AND WORKING

          As earlier mentioned, the Green engine is a six phase, internal combustion engine with much higher expansion ratio. The term “phase” is used instead of “stroke” because stroke is actually associated to the movement of the piston. The traveling of the piston from bottom dead centre to the top dead centre or vice versa is termed a stroke. But, in this engine pistons are absent and hence, the term “phase” is used. The six phases are: intake, compression, mixing, combustion, power and exhaust.

          The engine comprises a set of vanes, a pair of rotors which houses a number of small pot-like containers. It is here, in these small containers that compression, mixing, combustion are carried out. The engine also contains two air intake ports, and a pair of fuel injectors and spark plugs. The spark plugs are connected in such a system so as to deactivate them, when a fuel which does not need sparks for ignition is used. The rotor is made of high heat resistance and low expansion rate material such as ceramic. Whereas, the metal used is an alloy of steel, aluminium and chromium.

          Even though the engine is of symmetric shape, the vanes traverse an unsymmetrical or uneven boundary. This shape cannot be compromised as this a result of the path taken by the intake and exhaust air. This uneven boundary is covered by the vanes in a very unique fashion. The vanes are made in such a way that it comprises of two parts: one going inside a hollow one. At the bottom of the hollow vane is a compressive spring. On top of this spring is mounted the other part of the vane. Now, let us come to the working of the engine.

3.1 Intake

          The air arrives to the engine through the direct air intake port in the absence of an air inlet pipe, throttle and inlet valves on the air intake system. A duct is provided on the sides of the vane and rotor. The duct is so shaped that when the air moves through, strong swirls generate when it gets compressed in the chamber. The air pushes the vane blades which in turn impart a proportionate rotation in the small rotor which houses the chambers. The inlet air duct ends with a very narrow opening to the chamber.

3.2 Compression

          The rushing air from the duct is pushed by the blades into the small chambers in the rotor. The volume of these chambers is comparatively very small. Naturally, the compression obtained by such a procedure is very satisfactory. As earlier mentioned, the compressed air is in a swirling state, ready to be mixed with the fuel which will be injected into the chamber when it will be place before the injector by the already rotating rotor.

3.3 Mixing

          As soon as the chamber comes in front of the fuel injector, the injector sprays fuel into the compressed air. Because of the shape of the chamber, the fuel mixes well with the compressed air. The importance of ideal mixing leads to deletion of CO emission. And also because of the strong swirling, a centrifugal effect is exerted in the air-fuel mixture. Moreover, the rotation of the burner, makes this centrifugal effect all the more effective. Mixing phase has enough time to produce an ideal air-fuel mixture as the spark plug is positioned towards the other end of the rotor or burner.

3.4 Combustion

          As the chamber rotates towards the “end” of its path, it is positioned before the spark plug. A spark flies from the plug into the air-fuel mixture. Because of the mixing phase, the air-fuel mixture is denser near the spark plug, thereby, enabling lean-burning of the charge and also a uniform flame front. As soon as the whole charge is ignited, the burner rotates to position itself in front of the narrow exit.

3.5 Power

          The expanded gas rushes out of the chamber through the narrow opening, thereby pushing the name in the process. The sudden increase in volume ensures that more power is released. Or in other words, the thermal energy is fully utilized.

3.6 Exhaust

          As the thermal energy is fully utilized, the exhaust gases bring along comparatively less heat energy. This mainly helps in the thermal efficiency of the engine. It raises the engine’s thermal efficiency and also because of the complete burning of the charge, poisonous gases like CO are absent in the exhaust emissions.

4. ADVANTAGES

          As obvious from the technical features which include effective innovations, the advantages of the Green engine over the contemporary piston engines are many.

4.1 Small Size and Light Weight

          As Green engine is very compact with multi-power pulses, the size and weight could be 1/5 to 1/10 of the conventional piston engines on same output. Its power to weight ratio could be more than 2 hp per pound without supercharge or turbo charge.

4.2 Limited Parts

          There are only some dozens of parts easy to be manufactured in the engine structure.

4.3 High Efficiency

          Because many great innovations are being employed in the engine design such as: direct air intake, sequential variable compression ratio, super mixing process, constant volume combustion, controllable combustion time, high working temperature of the burner, high expansion ratio and self adapting sealing system etc., the thermal efficiency of the engine could be potentially as high as 65 %, even more if water add-in technology is to be considered.

4.4 Multi-fuels

          Due to six phases of working principle, super air fuel mixing process and constant volume combustion with controllable time, the Green engine becomes the only real multi-fuel engine on our planet; any liquid or gas fuels can be burnt well. Also it would be ideal to coal powder if special anti-wearing material is employed.

4.5 Near-zero Emissions

With perfect air-fuel mixture, complete combustion under lower peak temperature  and free of quenching effect, the emission of CO, HC and NO_x could be near zero, thereby, a catalytic converter could be not required at all.

4.6 Smooth Operation

          Due to inherence of good dynamic and static balance the performance of the Green engine is as smooth as an electric motor.

4.7 Fast Accelerating Response

          Direct injection, little rotating inertia and deleted reciprocating motion can characterize the Green engine with operating at a very fast accelerating response.

4.8 Quietness and Low Exhaust Temperature

          Burst out under small amount of mixtures, free of vibrations, and high expansion ratio make the Green engine much quieter. It is really environment-friendly. Green engine vehicles could transport troops on the battlefield of the future, and could serve as a vital source of auxiliary power in combat. This is because these engines are quiet, flexible and operate at low temperature, making them ideal for use in “stealth” vehicles.

4.9 Ideal to Hydrogen Fuel

          Separation of working chambers from each other is an ideal design for any fuel to prevent backfire, especially for the hydrogen fuel.

4.10 Highly Reliable

          As there are fewer moving parts operating smoothly, no crankshaft, valves, connecting rods, cams and timing chains, and intake and exhaust actions are accomplished directly by the motion of the vanes. Thus, it is highly reliable.

4.11 Low Cost

          Limited parts, small in size, light in weight and depending upon current mature materials and manufacturing technologies, mean that it would be done at much lower cost on manufacture, transportation, installing to other devices, and maintenance.

5. CONCLUSION

          The Green engine’s prototypes have been recently developed, and also because of the unique design, limitations have not been determined to any extent. But even in the face of limitations if any, the Green engine is sure to serve the purpose to a large extent.

6. REFERENCE

·        http://www.greenenginetech.com

·        Introduction to Internal Combustion Engines by Richard Stone

·        Engineering Fundamentals of the Internal Combustion Engine by Pulkrabek

·        Internal Combustion Engines by K.K. Ramalingam

ABSTRACT

 The green engine is one of the most interesting discoveries of the new millennium. It has got some unique features that were used for the first time in the making of engines. This engine is a piston less one with features like sequential variable compression ratio, direct air intake, direct fuel injection, multi-fuel usage etc. The efficiency of this engine is high when compared to the contemporary engines and also the exhaust emissions are near zero.  The significance of the engine lies in the efficiency when the present world conditions of limited resources of energy are considered. Prototypes of the engine have been developed. Generators have been produced with the green engine.

SCRAMJET (SEMINAR REPORT)

ABSTRACT
 A scramjet (supersonic combustion ramjet) is reminiscent of a ramjet. The basic components of scramjet are inlet, diffuser, fuel injector, flame holder, igniter, and combustion chamber and exhaust nozzle. The basic principle of scramjet is same as that of any type of engine, intake, compression, combustion, exhaust. NASA expects that future versions of this engine will serve as a low cost way to get payloads into orbit by lifting space cargoes to nearly atmospheric altitudes before they continue their journeys on rocket power. Scramjet advantages include simplicity of design, half an engine, carry more payloads, lower thrust to weight ratio, etc. Scramjet disadvantages include additional propulsion requirements, testing difficulties, lack of stealth, need of additional engines etc. Scramjet is used for space applications, civil applications and military applications. Recent progress in scramjet developments are Hyshot, Hyper-X, GASL projectile etc.


1. INTRODUCTION


Space was always a dream for man. There was always a passion for human beings since the time of antiquity to fly like a bird. Here the passion takes precedence. His dream has no limits. It leads him to do lot of experiments to foray the Milky Way. Some may have failed but finally he succeeded in his attempts and that pave the way for Aeronautical Technology.
One thing has always been true about rockets: The farther and faster you want to go, the bigger your rocket needs to be. Rockets combine a liquid fuel with liquid oxygen to create thrust. Take away the need for liquid oxygen and your spacecraft can be smaller or carry more pay load.
During and after World War II, tremendous amounts of time and effort were put into researching high-speed jet- and rocket-powered aircraft. The Bell X-1 attained supersonic flight in 1947, and by the early 1960s, rapid progress towards faster aircraft suggested that operational aircraft would be flying at "hypersonic" speeds within a few years. Except for specialized rocket research vehicles like the North American X-15 and other rocket-powered spacecraft, aircraft top speeds have remained level, generally in the range of Mach 1 to Mach 2.
That's the idea behind a different propulsion system called "SCRAMJET", or Supersonic Combustion Ramjet: The oxygen needed by the engine to combust is taken from the atmosphere passing through the vehicle, instead of from a tank onboard. The craft becomes smaller, lighter and faster. Researchers predict scramjet speeds could reach 15 times the speed of sound. An 18-hour trip to Tokyo from New York City becomes a 2-hour flight.
The university of Queensland’s Hyshot team, Australia reported in 1995, the first development of a scramjet and in 2002 successfully tested the first ever scramjet system. It had a speed of Mach 7, or seven times the speed of sound.


2. RAMJET

A ramjet, sometimes referred to as a stovepipe jet, or an athodyd, is a form of jet engine using the engine's forward motion to compress incoming air, without a rotary compressor. Ramjets cannot produce thrust at zero airspeed and thus cannot move an aircraft from a standstill. Ramjets require considerable forward speed to operate well, and as a class work most efficiently at speeds around Mach 3. This type of jet can operate up to speeds of Mach 6.
. An object moving at high speed through air generates a high pressure region in front and a low pressure region to the rear. A ramjet uses this high pressure in front of the engine to force air through the tube, where it is heated by combusting some of it with fuel. It is then passed through a nozzle to accelerate it to supersonic speeds. This acceleration gives the ramjet forward thrust.
 
FROM RAMJET TO SCRAMJET
Beyond Mach = 5 (hypersonic domain), ramjet is less and less efficient. Increasing of air stagnation temperature and pressure tends to limit the performance and to increase the thermal and mechanical loads on the combustion chamber walls
To bypass these issues, the solution is to maintain the flow supersonic from the air inlet to the engine exit and to achieve the combustion in the supersonic flow

3. SCRAMJET

A scramjet (supersonic combustion ramjet) is a variant of a ramjet air breathing combustion jet engine in which the combustion process takes place in supersonic airflow. As in ramjets, a scramjet relies on high vehicle speed to forcefully compress and decelerate the incoming air before combustion (hence ramjet), but whereas a ramjet decelerates the air to subsonic velocities before combustion, airflow in a scramjet is supersonic throughout the entire engine. This allows the scramjet to efficiently operate at extremely high speeds: theoretical projections place the top speed of a scramjet between Mach 12 and Mach 24, which is near orbital velocity


The scramjet is composed of three basic components: a converging inlet, where incoming air is compressed and decelerated; a combustor, where gaseous fuel is burned with atmospheric oxygen to produce heat; and a diverging nozzle, where the heated air is accelerated to produce thrust. Unlike a typical jet engine, such as a turbojet or turbofan engine, a scramjet does not use rotating, fan-like components to compress the air; rather, the incredible speed of the aircraft moving through the atmosphere causes the air to compress within the nozzle. As such, very few moving parts are needed in a scramjet, which greatly simplifies both the design and operation of the engine. In comparison, typical turbojet engines require inlet fans, multiple stages of rotating compressor, and multiple rotating turbine stages, all of which add weight, complexity, and a greater number of failure points to the engine. It is this simplicity that allows scramjets to operate at such high velocities, as the conditions encountered in hypersonicflight severely hamper the operation of conventional turbo machinery.
Scramjet engines are a type of jet engine, and rely on the combustion of fuel and an oxidizer to produce thrust. Similar to conventional jet engines, scramjet-powered aircraft carry the fuel on board, and obtain the oxidizer by the ingestion of atmospheric oxygen (as compared torockets, which carry both fuel and an oxidizing agent). This requirement limits scramjets to suborbital atmospheric flight, where the oxygen content of the air is sufficient to maintain combustion.

4. SCRAMJET PROPULSION

A ramjet engine provides a simple, light propulsion system for high speed flight. Likewise, the supersonic combustion ramjet, or scramjet, provides high thrust and low weight for hypersonic flight speeds. Unlike a turbojet engine, ramjets and scramjets have no moving parts, only an inlet, and a combustor that consists of a fuel injector and a flame holder, and a nozzle. When mounted on a high speed aircraft, large amounts of surrounding air are continuously brought into the engine inlet because of the forward motion of the aircraft. The air is slowed going through the inlet, and the dynamic pressure due to velocity is converted into higher static pressure. At the exit of the inlet, the air is at a much higher pressure than free stream. While the free stream velocity may be either subsonic or supersonic, the flow exiting the inlet of a ramjet is always subsonic. The flow exiting a scramjet inlet is supersonic and has fewer shock losses than a ramjet inlet at the same vehicle velocity.
In the burner, a small amount of fuel is combined with the air and ignited. In a typical engine, 100 pounds of air/sec. is combined with only 2 pounds of fuel/sec. Most of the hot exhaust has come from the surrounding air. Flame holders in the burner localize the combustion process. Burning occurs subsonically in the ramjet and supersonically in the scramjet. Leaving the burner, the hot exhaust passes through a nozzle, which is shaped to accelerate the flow. Because the exit velocity is greater than the free stream velocity, thrust is created as described by the general thrust equation. For ramjet and scramjet engines, the exit mass flow is nearly equal to the free stream mass flow, since very little fuel is added to the stream.



5. ADVANTAGES OF SCRAMJET

Special cooling and materials: Unlike a rocket that quickly passes mostly vertically through the atmosphere or a turbojet or ramjet that flies a “depressed trajectory”, staying within the atmosphere at hypersonic speeds .Because scramjet have only mediocre thrust-to-weight ratios , acceleration would be limited. Therefore time in the atmosphere at hypersonic speeds would be considerable, possibly 15-30 minutes. Similar to a reentering space vehicle, heat insulation from atmospheric friction would be a formidable task. The time in the atmosphere would be greater than that for a typical space capsule, but less than that of the space shuttle. Often, however, the coolant is the fuel itself, much in the same that modern rockets use their own fuel and oxidizer as coolant for their engines. Both scramjets and conventional rockets are at risk in the event of a cooling failure.
Half an engine: The typical wave rider scramjet concept involves, effectively, only half an engine. The shock wave of the vehicle itself compresses the expanding gases, forming the other half .Likewise; only fuel (the light component) needs tank, pumps, etc. This greatly reduces craft mass and construction effort, but the resultant engine is still very much heavier than an equivalent rocket or convection turbojet engine of similar thrust.
Simplicity of design: Scramjets have few to no moving parts. Most of their body consists of numerous surfaces. With simple fuel pumps, reduced total components, and the reentry system being the crank itself, scramjet development tends to be more of a materials and modeling problem than anything else.
Carry more payloads: An advantage of hypersonic air breathing (typically scramjet) vehicle is avoiding or at least reducing the need for carrying oxidizer.75% of the entire assembly weight is liquid oxygen. If carrying this could be eliminated, the vehicle could be lighter at takeoff and hopefully carry more pay loads .That could be a major advantage, but the central motivation in pursuing hypersonic air breathing vehicles would be to reduce costs.

Costs: Reducing the amount of fuel and oxidizer, as in scramjets, means that the vehicle itself becomes a much larger percentage of the costs (rocket fuels are already cheap).Indeed, the unit cost of the vehicle can be expected to end up far higher, since the aerospace hardware cost is probably about two orders of magnitude higher than liquid oxygen and tank age. Still, if scramjets enable reusable vehicles, this could theoretically be a cost benefit. Whether equipment subject to the extreme conditions of a scramjet can be reused sufficiently many times is unclear; all flown scramjet tests are only designed to survive for short periods.
It is likely that a scramjet vehicle would need to lift more load than a rocket of equal takeoff weight in order to be equally as cost efficient (if the scramjet is a non-reusable vehicle).



6. DISADVANTAGES OF SCRAMJET

Additional propulsion requirements: A scramjet cannot produce efficient thrust unless boosted to high speed, at least Mach 5. Therefore a horizontal take off aircraft could need convectional rocket engines to take off, sufficiently large to move a heavy craft. Also needed would be fuel for such engines, plus all engine associated mounting structure and control systems .So another propulsion method would be needed to reach scramjet operating speed. That could be ramjets or rockets. Those would also need their own separate fuel supply, structure and systems. Many proposals instead call for a first stage of droppable solid rocket boosters, which greatly simplifies the design.

Testing difficulties: Unlike jet or rocket propulsion systems facilities which can be tested on the ground, testing scramjet designs uses extremely expensive hypersonic test chambers or expensive launch vehicles, both of which lead to high instrumentation costs. Launched test vehicles very typically end with destruction of the test item and instrumentation.

Lack of stealth: There is no published way to make a scramjet powered vehicle stealthy, since the vehicle would be very hot due to its high speed within the atmosphere. So it should be easy to detect with infrared sensors.


7. APPLICATIONS

CIVIL APPLICATIONS
Scramjet speed could reach 15 times the speed of sound. An aircraft using this type of jet engine could dramatically reduce the time it takes to travel from one place to another, potentially putting any place on earth within a 90 minutes flight. I.e. an 18 hour trip to Tokyo from New York City or from becomes a 2 hour flight.
MILITARY APPLICATIONS
Scramjet can be used o propel missiles .They are found almost exclusively in missiles where they are boosted to operating speeds by a rocket engine or being attached ton another aircraft, typically a fighter. Currently used scramjet propelled missiles are
(1) British Bloodhound Surface to air missile
(2) British MBDA Meteor Air to air missile
(3) Russian Indian Brahmos Supersonic cruise missile
 
8. SCRAMJET AND N.A.S.A

In its maiden test flight last June, a hypersonic plane developed by NASA veered off course and was destroyed. Despite the failure, the agency in now trying to breathe new life into it tests of the craft’s novel engine, called a scramjet. NASA expects that future versions of the engine will swerve as a low cost way to get pay loads into orbit by lifting space cargoes to nearly stratospheric altitudes before they continue their journeys on rocket power.
A conventional jet engine, with its spinning blades and turbines, would tear apart at lower speeds; but the scramjet has no moving parts. That means air can safely rush through it at many times the speed of sound, combust with hydrogen fuel to boost the vehicle to hypersonic speeds (above mach 5).Of course, conventional liquid fuelled rockets fly even faster, but they must carry both fuel and oxygen needed to burn it-an expensive proposition. A future craft with both scramjet and rocket power could travel to the edge of space before firing its rockets, requiring less oxygen and leaving more room for the pay load
If NASA does get its craft off the ground, those waiting for a cheaper, more efficient way to space can begin breathe easier.

9. RECENT PROGRESS


In recent years, significant progress has been made in the development of hypersonic technology, particularly in the field of scramjet engines. While American efforts are probably the best funded, the first to demonstrate a scramjet working in an atmospheric test was a shoestring project by an Australian team at the University of Queensland. The university's HyShot project demonstrated scramjet combustion in 2002. This demonstration was somewhat limited, however; while the scramjet engine worked effectively and demonstrated supersonic combustion in action, the engine was not designed to provide thrust to propel a craft.
The US Air Force and Pratt and Whitney have cooperated on the Hypersonic Technology (HyTECH) scramjet engine, which has now been demonstrated in a wind-tunnel environment. NASA's Marshall Space Propulsion Center has introduced an Integrated Systems Test of an Air-Breathing Rocket (ISTAR) program, prompting Pratt & Whitney, Aerojet, and Rocketdyne to join forces for development.
To coordinate hypersonic technology development, the various factions interested in hypersonic research have formed two integrated product teams (IPTs): one to consolidate Army, Air Force, and Navy hypersonic weapons research, the other to consolidate Air Force and NASA space transportation and hypersonic aircraft work. Current funding levels are relatively low, no more than US$85 million per year in total, but are expected to rise.
The most advanced US hypersonics program is the US$250 million NASA Langley Hyper-X X-43A effort, which flew small test vehicles to demonstrate hydrogen-fueled scramjet engines. NASA is worked with contractors Boeing, Microcraft, and the General Applied Science Laboratory (GASL) on the project.
The NASA Langley, Marshall, and Glenn Centers are now all heavily engaged in hypersonic propulsion studies. The Glenn Center is taking leadership on a Mach 4 turbine engine of interest to the USAF. As for the X-43A Hyper-X, three follow-on projects are now under consideration:
X-43B: A scaled-up version of the X-43A, to be powered by the ISTAR engine. ISTAR will use a hydrocarbon-based liquid-rocket mode for initial boost, a ramjet mode for speeds above Mach 2.5, and a scramjet mode for speeds above Mach 5 to take it to maximum speeds of at least Mach 7. A version intended for space launch could then return to rocket mode for final boost into space. ISTAR is based on a proprietary Aerojet design called a "strutjet", which is currently undergoing wind-tunnel testing.

X-43C: NASA is in discussions with the Air Force on development of a variant of the X-43A that would use the HyTECH hydrocarbon-fueled scramjet engine.
While most scramjet designs to date have used hydrogen fuel, HyTech runs on conventional kerosene-type hydrocarbon fuels, which are much more practical for support of operational vehicles. A full-scale engine is now being built, which will use its own fuel for cooling. Using fuel for engine cooling is nothing new, but the cooling system will also act as a chemical reactor, breaking long-chain hydrocarbons down into short-chain hydrocarbons that burn more rapidly.
X-43D: A version of the X-43A with a hydrogen-powered scramjet engine with a maximum speed of Mach 15.
Hypersonic development efforts are also in progress in other nations. The French are now considering their own scramjet test vehicle and are in discussions with the Russians for boosters that would carry it to launch speeds. The approach is very similar to that used with the current NASA X-43A demonstrator.
Several scramjet designs are now under investigation with Russian assistance. One of these options or a combination of them will be selected by ONERA, the French aerospace research agency, with the EADS conglomerate providing technical backup. The notional immediate goal of the study is to produce a hypersonic air-to-surface missile named "Promethee", which would be about 6 meters (20 ft) long and weigh 1,700 kilograms (3,750 lb).

10. SCRAMJET PROGRAMMES

HYSHOT
On July 30, 2002, the University of Queensland's HyShot team conducted the first ever test successful flight of a scramjet.
The team took a unique approach to the problem of accelerating the engine to the necessary speed by using an Orion-Terrier rocket to take the aircraft up on a parabolic trajectory to an altitude of 314 km. As the craft re-entered the atmosphere, it dropped to a speed of Mach 7.6. The scramjet engine then started, and it flew at about Mach 7.6 for 6 seconds. [1]. This was achieved on a lean budget of just A$1.5 million (US $1.1 million), a tiny fraction of NASA's $US 250 million to develop the X-43A.
NASA has partially explained the tremendous difference in cost between the two projects by pointing out that the American vehicle has an engine fully incorporated into an airframe with a full complement of flight control surfaces available.
HYPER-X
NASA's Hyper-X program is the successor to the National Aerospace Plane (NASP) program which was cancelled in November 1994. This program involves flight testing through the construction of the X-43 vehicles. NASA first successfully flew its X-43A scramjet test vehicle on March 27, 2004 (an earlier test, on June 2, 2001 went out of control and had to be destroyed). Unlike the University of Queensland's vehicle, it took a horizontal trajectory. After it separated from its mother craft and booster, it briefly achieved a speed of 5,000 miles per hour (8,000 km/h), the equivalent of Mach 7, easily breaking the previous speed record for level flight of an air-breathing vehicle. Its engines ran for eleven seconds, and in that time it covered a distance of 15 miles (24 km). The Guinness Book of Records certified the X-43A's flight as the current Aircraft Speed Record holder on 30 August 2004. The third X-43 flight set a new speed record of 6,600 mph (10,621 km/h), nearly Mach 10 on 16 November 2004. It was boosted by a modified Pegasus rocket which was launched from a Boeing B-52 at 13,157 meters (40,000 feet). After a free flight where the scramjet operated for about ten seconds the craft made a planned crash into the Pacific ocean off the coast of southern California. The X-43A craft were designed to crash into the ocean without recovery. Duct geometry and performance of the X-43 are classified.
(a) RUSSIA AND FRANCE (AND NASA)
On November 17, 1992, Russian scientists with some additional French support successfully launched a scramjet engine in Kazakhstan. From 1994 to 1998 NASA worked with the Russian central institute of aviation motors (CIAM) to test a dual-mode scramjet engine. Four tests took place, reaching Mach numbers of 5.5, 5.35, 5.8, and 6.5. The final test took place aboard a modified SA-5 surface to air missile launched from the Sary Shagan test range in the Republic of Kazakhstan on 12 February 1998. Data regarding whether the internal combustion took place in supersonic air streams was inconclusive, according to NASA. No net thrust was achieved. The tests also included French partners.
(b) GASL PROJECTILE
At a test facility at Arnold Air Force Base in the U.S. state of Tennessee, GASL fired a projectile equipped with a hydrocarbon-powered scramjet engine from a large gun. On July 26, 2001, the four inch (100 mm) wide projectile covered a distance of 260 feet (79 m) in 30 milliseconds (roughly 5,900 mph or 9,500 km/h). The projectile is supposedly a model for a missile design. Many do not consider this to be a scramjet "flight," as the test took place near ground level. However, the test environment was described as being very realistic.

11. SCRAMJET TESTING REACHES MAJOR MILESTONE
A team of researchers from Air Force and industry achieved a major milestone on the development path to demonstrate a hydrocarbon fueled, supersonic combustion ramjet, or scramjet, engine. Such propulsive power will enable weapons that will dramatically increase range and decrease the reaction time when employed against high-value targets at long standoff ranges.


Built under the AFRL’s Propulsion Directorate’s Hi-Tech program, the Performance Test Engine, or PTE, successfully completed a series of free jet tests at Mach 4.5 and 6.5. The PTE is an integrated engine with inlet, combustor, and nozzle. Pratt & Whitney developed this heavyweight, heat sink demonstrator engine under contract to AFRL. The tests were conducted at the GASL facilities at Ronkonkoma, New York. The PTE met or exceeded performance goals.

The Hi-Tech program is the latest in a long series of Air Force efforts to prove the viability and utility of the supersonic combustion ramjet engine. The program is focused to establish a scramjet technology base with near term applications to hypersonic cruise missiles. This technology base can be expanded to include reusable hypersonic vehicles such as strike/reconnaissance and affordable access to space vehicles. By maturing scramjet propulsion, researchers will provide a key component to a new breed of propulsion systems known as the combined or combination cycle engines. These combine turbine, ramjet, scramjet and/or rocket engines, using each of the different cycles to the fullest advantage of their respective efficiencies to optimize overall system performance. Such propulsion systems have the potential to enable a family of vehicles, including global range, high speed aircraft, and “space plane” type vehicles for on-demand access to space.

12. CONCLUSION

Scramjet programme is a fast developing field in the present world. There are many applications with scramjet. It provides a cheaper and efficient access to space. Scramjet has the potential for supersonic or hypersonic transportation. Scramjet technologies are also used for military applications. But scramjet technologies still need developments. Scramjet in future will provide us cheaper and faster access to any part in this universe. Also the craft will become smaller and lighter and can carry more payloads.

13. BIBLIOGRAPHY


1. Aircraft and Missile Propulsion M J ZUCROW, JOHN WILLEY

2. Aircraft Propulsion P J Mc MAHON, HARPET ROW

3. Hypersonic Air breathing Propulsion W H HEISER, D T PRATT

4. http://www.wikipedia.org

5. http://www.scramjet.com

6. http://www.nasa.com

7. http://www.aerospaceweb.org

the-Hy-wire-car-full-report

ABSTRACT
Hy-Wire Car is without mechanical and hydraulic linkage end engine. Instead of these it contain a fuel cell stack and a drive by wire system. It is fully automated car it is a future car. In future it will have a wide application. The problem with fuel consumption and pollution can be minimize to certain level. 

Chapter I
INTRODUCTION
Cars are immensely complicated machines, but when you get down to it, they do an incredibly simple job. Most of the complex stuff in a car is dedicated to turning wheels, which grip the road to pull the car body and passengers along. The steering system tilts the wheels side to side to turn the car, and brake and acceleration systems control the speed of the wheels. Given that the overall function of a car is so basic (it just needs to provide rotary motion to wheels), it seems a little strange that almost all cars have the same collection of complex devices crammed under the hood and the same general mass ofmechanical and hydraulic linkages running throughout. Why do cars necessarily need a steering column, brake and acceleration pedals, a combustion engine, a catalytic converter and the rest of it? According to many leading automotive engineers, they don't; and more to the point, in the near future, they won't. Most likely, a lot of us will be driving radically different cars within 20 years. And the difference won't just be under the hood -- owning and driving cars will change significantly, too. In this article, we'll look at one interesting vision of the future, General Motor's remarkable concept car, the Hy-wire. GM may never actually sell the Hy-wire to the public, but it is certainly a good illustration of various ways cars might evolve in the near future.
GM's sedan model Hy-wire

Chapter- II
HY-WIRE BASICS
Two basic elements largely dictate car design today: the internal combustion engine and mechanical and hydraulic linkages. If you've ever looked under the hood of a car, you know an internal combustion engine requires a lot of additional equipment to function correctly. No matter what else they do with a car, designers always have to make room for this equipment.
The same goes for mechanical and hydraulic linkages. The basic idea of this system is that the driver maneuvers the various actuators in the car (the wheels, brakes, etc.) more or less directly, by manipulating driving controls connected to those actuators by shafts, gears and hydraulics. In a rack-and-pinion steering system, for example, turning the steering wheel rotates a shaft connected to a pinion gear, which moves a rack gear connected to the car's front wheels. In addition to restricting how the car is built, the linkage concept also dictates how we drive: The steering wheel, pedal and gear -shift system were all designed around the linkage idea. The defining characteristic of the Hy-wire (and its conceptual predecessor, the Autonomy) is that it doesn't have either of these two things. Instead of an engine, it has a fuel cell stack, which powers an electric motor connected to the wheels. Instead ofmechanical and hydraulic linkages, it has a drive by wire system -- a computer actually operates the components that move the wheels, activate the brakes and so on, based on input from an electronic controller. This is the same control system employed in modern fighter jets as well as many commercial planes.
The result of these two substitutions is a very different type of car -- and a very different driving experience. There is no steering wheel, there are no pedals and there is no engine compartment. In fact, every piece of equipment that actually moves the car along the road is housed in an 11-inch-thick (28 cm) aluminum chassis -- also known as the skateboard -- at the base of the car. Everything above the chassis is dedicated solely to driver control and passenger comfort. This means the driver and passengers don't have to sit behind a mass of machinery. Instead, the Hy-wire has a huge front windshield, which gives everybody a clear view of the road. The floor of the fiberglass-and-steel passenger compartment can be totally flat, and it's easy to give every seat lots of leg room. Concentrating the bulk of the vehicle in the bottom section of the car also improves safety because it makes the car much less likely to tip over.
But the coolest thing about this design is that it lets you remove the entire passenger compartment and replace it with a different one. If you want to switch from a van to a sports car, you don't need an entirely new car; you just need a new body (which is a lot cheaper). The Hy-wire has wheels, seats and windows like a conventional car, but the similarity pretty much ends there. There is no engine under the hood and no steering wheel or pedals inside.

Chapter III
POWER
The "Hy" in Hy-wire stands for hydrogen, the standard fuel for a fuel cell system. Like batteries, fuel cells have a negatively charged terminal and a positively charged terminal that propel electrical charge through a circuit connected to each end. They are also similar to batteries in that they generate electricity from a chemical reaction. But unlike a battery, you can continually recharge a fuel cell by adding chemical fuel -- in this case, hydrogen from an onboard storage tank and oxygen from the atmosphere.
The basic idea is to use a catalyst to split a hydrogen molecule (H2) into two H protons (H+, positively charged single hydrogen atoms) and two electrons (e-). Oxygen on the cathode (positively charged) side of the fuel cell draws H+ ions from the anode side through a proton exchange membrane, but blocks the flow of electrons. The electrons (which have a negative charge) are attracted to the protons (which have a positive charge) on the other side of the membrane, but they have to move through the electrical circuit to get there. The moving electrons make up the electrical current that powers the various loads in the circuit, such as motors and the computer system. On the cathode side of the cell, the hydrogen, oxygen and free electrons combine to form water (H2O), the system's only emission product.
In a hydrogen fuel cell, a catalyst breaks hydrogen molecules in the anode into protons and electrons. The protons move through the exchange membrane, toward the oxygen on the cathode side, and the electrons make their way through a wire between the anode and cathode. On the cathode side, the hydrogen and oxygen combine to form water. Many cells are connected in series to move substantial charge through a circuit.
In a hydrogen fuel cell, a catalyst breaks hydrogen molecules in the anode into protons and electrons. The protons move through the exchange membrane, toward the oxygen on the cathode side, and the electrons make their way through a wire between the anode and cathode. On the cathode side, the hydrogen and oxygen combine to form water. Many cells are connected in series to move substantial charge through a circuit.
One fuel cell only puts out a little bit of power, so you need to combine many cells into a stack to get much use out of the process. The fuel-cell stack in the Hy-wire is made up of 200 individual cells connected in series, which collectively provide 94 kilowatts of continuous power and 129 kilowatts at peak power. The compact cell stack (it's about the size of a PC tower) is kept cool by a conventional radiator system that's powered by the fuel cells themselves. The hydrogen tanks and fuel-cell stack in the Hy-wire .
This system delivers DC voltage ranging from 125 to 200 volts, depending on the load in the circuit. The motor controller boosts this up to 250 to 380 volts and converts it to AC current to drive the three-phase electric motor that rotates the wheels (this is similar to the system used in conventional electric cars).
The electric motor's job is to apply torque to the front wheel axle to spin the two front wheels. The control unit varies the speed of the car by increasing or decreasing the power applied to the motor. When the controller applies maximum power from the fuel-cell stack, the motor's rotor spins at 12,000 revolutions per minute, delivering a torque of 159 pound-feet. A single-stage planetary gear, with a ratio of 8.67:1, steps up the torque to apply a maximum of 1,375 pound-feet to each wheel. That's enough torque to move the 4,200-pound (1,905-kg) car 100 miles per hour (161 kph) on a level road. Smaller electric motors maneuver the wheels to steer the car, and electrically controlled brake calipers bring the car to a stop. The gaseous hydrogen fuel needed to power this system is stored in three cylindrical tanks, weighing about 165 pounds (75 kilograms) total. The tanks are made of a special carbon composite material with the high structural strength needed to contain high-pressure hydrogen gas. The tanks in the current model hold about 4.5 pounds (2 kg) of hydrogen at about 5,000 pounds per square inch (350 bars). In future models, the Hy-wire engineers hope to increase the pressure threshold to 10,000 pounds per square inch (700 bars), which would boost the car's fuel capacity to extend the driving range.
Ultimately, GM hopes to get the fuel-cell stack, motors and hydrogen-storage tanks small enough that they can reduce the chassis thickness from 11 inches to 6 inches (15 cm). This more compact "skateboard" would allow for even more flexibility in the body design.

Chapter IV
CONTROL
The Hy-wire's "brain" is a central computer housed in the middle of the chassis. It sends electronic signals to the motor control unit to vary the speed, the steering mechanism to maneuver the car, and the braking system to slow the car down.
At the chassis level, the computer controls all aspects of driving and power use. But it takes its orders from a higher power -- namely, the driver in the car body. The computer connects to the body's electronics through a single universal docking port. This central port works the same basic way as a USB port on a personal computer: It transmits a constant stream of electronic command signals from the car controller to the central computer, as well as feedback signals from the computer to the controller. Additionally, it provides the electric power needed to operate all of the body's onboard electronics. Ten physical linkages lock the body to the chassis structure.

The driver's control unit, dubbed the X-drive, is a lot closer to a video game controller than a conventional steering wheel and pedal arrangement. The controller has two ergonomic grips, positioned to the left and right of a small LCD monitor. To steer the car, you glide the grips up and down lightly -- you don't have to keep rotating a wheel to turn, you just have to hold the grip in the turning position. To accelerate, you turn either grip, in the same way you would turn the throttle on a motorcycle; and to brake, you squeeze either grip.
Electronic motion sensors, similar to the ones in high-end computer joysticks, translate this motion into a digital signal the central computer can recognize. Buttons on the controller let you switch easily from neutral to drive to reverse, and a starter button turns the car on. Since absolutely everything is hand-controlled, you can do whatever you want with your feet (imagine sticking them in a massager during the drive to and from work every day).


The X-drive can slide to either side of the vehicle.

The 5.8-inch (14.7-cm) color monitor in the center of the controller displays all the stuff you'd normally find on the dashboard (speed, mileage, fuel level). It also gives you rear-view images from video cameras on the sides and back of the car, in place of conventional mirrors. A second monitor, on a console beside the driver, shows you stereo, climate control and navigation information.
Since it doesn't directly drive any part of the car, the X- drive could really go anywhere in the passenger compartment. In the current Hy-wire sedan model, the X-drive swings around to either of the front two seats, so you can switch drivers without even getting up. It's also easy to adjust the X-drive up or down to improve driver comfort, or to move it out of the way completely when you're not driving.
One of the coolest things about the drive-by-wire system is that you can fine-tune vehicle handling without changing anything in the car's mechanical components -- all it takes to adjust the steering, accelerator or brake sensitivity is some new computer software. In future drive-by-wire vehicles, you will most likely be able to configure the controls exactly to your liking by pressing a few buttons, just like you might adjust the seat position in a car today. It would also be possible in this sort of system to store distinct control preferences for each driver in the family.


The big concern with drive-by-wire vehicles is safety. Since there is no physical connection between the driver and the car's mechanical elements, an electrical failure would mean total loss of control. In order to make this sort of system viable in the real world, drive-by-wire cars will need back-up power supplies and redundant electronic linkages. With adequate safety measures like this, there's no reason why drive-by-wire cars would be any more dangerous than conventional cars. In fact, a lot of designers think they'll be much safer, because the central computer will be able to monitor driver input. Another problem is adding adequate crash protection to the car. The other major hurdle for this type of car is figuring out energy-efficient methods for producing, transporting and storing hydrogen for the onboard fuel-cell stacks. With the current state of technology, actually producing the hydrogen fuel can generate about as much pollution as using gasoline engines, and storage and distribution systems still have a long way to go (see How the Hydrogen Economy Works for more information). So will we ever get the chance to buy a Hy-wire? General Motors says it fully intends to release a production version of the car in 2010, assuming it can resolve the major fuel and safety issues. But even if the Hy-wire team doesn't meet this goal, GM and other automakers are definitely planning to move beyond the conventional car sometime soon, toward a computerized, environmentally friendly alternative. In all likelihood, life on the highway will see some major changes within the next few decades. Chapter -V
HY-WIRE CAR SPECIFICATION
Top speed: 100 miles per hour (161 kph)
Weight: 4,185 pounds (1,898 kg)
Chassis length: 14 feet, 3 inches (4.3 meters)
Chassis width: 5 feet, 5.7 inches (1.67 meters)
Chassis thickness: 11 inches (28 cm)
Wheels: eight-spoke, light alloy wheels.
Tires: 20-inch (51-cm) in front and 22-inch (56-cm) in back
Fuel-cell power: 94 kilowatts continuous, 129 kilowatts peak
Fuel-cell-stack voltage: 125 to 200 volts
Motor: 250- to 380-volt three-phase asynchronous electric motor
Crash protection: front and rear "crush zones" (or "crash
boxes") to absorb impact energy
Related GM patents in progress: 30
GM team members involved in design: 500+

CONCLUSION
By using Hy-Wire technology certain multi national companies like General Motors is fully intended to release a production version of the car in 2010, assuming it can resolve the major fuel and safety issues. The life on the high way will see some major changes within the next few decades.
REFERENCES
http://www.howstuffworks.com
http://www.generalmoters.com

MAGNETIC LEVITATION-ME

 INTRODUCTION

                                    Magnetic levitation is the latest in transportation technology and has been the interest of many countries around the world. The idea has been around since 1904 when Robert Goddard, an American Rocket scientist, created a theory that trains could be lifted off the tracks by the use of electromagnetic rails. Many assumptions and ideas were brought about throughout the following years, but it was not until the 1970’s that Japan and Germany showed interest in it and began researching and designing.

                  The motion of the Maglev train is based purely on magnetism and magnetic fields. This magnetic field is produced by using high-powered electromagnets. By using magnetic fields, the Maglev train can be levitated above its track, or guideway, and propelled forward. Wheels, contact with the track, and moving parts are eliminated on the Maglev train, allowing the Maglev train to essentially move on air without friction.

FIGURE[1]

BASIC PRINCIPLE OF MAGLEV TRAIN

                  Maglev can be used for both low and high speed transportation. The low speed Maglev is used for short distance travel. Birmingham, England used this low speed transportation between the years of 1984 and 1995. However, engineers are more interested in creating the high-speed Maglev vehicles. The higher speed vehicle can travel at speeds of nearly 343mph or 552 km/h. Magnetic Levitation mainly uses two different types of suspension, which are Electromagnetic Suspension and Electrodynamic Suspension. However, a third suspension system (Intuctrack) has recently been developed and is in the research and design phase. These suspension systems are what keep the train levitated off the track.

PROPULSION SYSTEM

Electrodynamic Propulsion is the basis of the movement in a Maglev system. The basic principle that electromagnetic propulsion follows is that “opposite poles attract each other and like poles repel each other”. This meaning that the north pole of a magnet will repel the north pole of a magnet while it attracts the south pole of a magnet. Likewise, the south pole of a magnet will attract the north pole and repel the south pole of a magnet. It is important to realize these three major components of this propulsion system. They are:

·          A large electrical power source

·          Metal coils that line the entire guideway

·          Guidance magnets used for alignment

            The Maglev system does not run by using a conventional engine or fossil fuels. The interaction between the electromagnets and guideway is the actual motor of the Maglev system. To understand how Maglev works without a motor, we will first introduce the basics of a traditional motor. A motor normally has two main parts, a stator and a rotor. The outer part of the motor is stationary and is called the stator. The stator contains the primary windings of the motor. The polarity in the stator is able to rapidly change from north and south. The inner part of the motor is known as the rotor, which rotates because of the outer stator. The secondary windings are located within the rotor. A current is applied to the secondary wingings of the rotor from  a voltage in the stator that is caused by a magnetic force in the primary windings.  As a result, the rotor is able to rotate.

      Now that we have an understanding of how motors work, we can describe how Maglev uses a variation on the basic ideas of a motor. Although not an actual motor, the Maglev’s propulsion system uses an electric synchronous motor or a linear synchronous motor. The Maglev system works in the same general way the compact motor does, except it is linear, “meaning it is stretched as far as the track goes”. The stators of the Maglev system are usually in the guiderails, whereas the rotors are located within the electromagnetic system on the train. The sections of track that contain the stators are known as stator packs. This linear motor is essential to any Maglev system. The picture below gives an idea of where the stator pack and motor windings are located.

FIGURE[2]

·                      Parts of the Electromagnetic System

·                       

      The guideway for Maglev systems is made up of magnetized coils, for both levitation and propulsion, and the stator packs. “An alternating current is then produced, from the large power source, and passes through the guideway, creating an electromagnetic field which travels down the rails”. As defined by the Encarta Online dictionary, an alternating current is “a current that reverses direction.” The strength of this current can be made much greater than the normal strength of a magnet by increasing the number of winds in the coils. The current in the guideway must be alternating so the polarity in the magnetized coils can change. The alternating current allows a pull from the magnetic field in front of the train, and a push from the magnetic field behind the train. This push and pull motion work together allowing the train to reach maximum velocities well over 300 miles per hour.

FIGURE[3]

PROPULSION SYSTEM IN EDS

            This propulsion is unique in that the current is able to be turned on and off quickly. Therefore, at one instance there can be a positive charge running through a section of the track, and within a second it could have a neutral charge. This is the basic principle behind slowing the vehicle down and breaking it. The current through the guiderails is reversed causing the train to slow, and eventually to competely stop. Additionally, by reversing the current, the train would go in the reverse direction. This propulsion system gives the train enough power to accelerate and decelerate fairly quickly, allowing the train to easily climb steep hills.

      The levitation, guidance, and propulsion of the electromagnetic suspension system must work together in order for the Maglev train to move. All of the magnetic forces are computer controlled to provide a safe and hazard free ride. The propulsion system works hand in hand with the suspension system on the Maglev system.

MAGNETIC LEVITATION SYSTEM

Magnetic levitation means “to rise and float in air”. The Maglev system is made possible by the use of electromagnets and magnetic fields. The basic principle behind Maglev is that if you put two magnets together in a certain way there will be a strong magnetic attraction and the two magnets will clamp together. This is called "attraction". If one of those magnets is flipped over then there will be a strong magnetic repulsion and the magnets will push each other apart. This is called "repulsion". Now imagine a long line of magnets alternatively placed along a track. And a line of alternatively placed magnets on the bottom of the train. If these magnets are properly controlled the trains will lift of the ground by the magnetic repulsion or magnetic attraction. On the basis of this principle, Magnetic Levitation is broken into two main types of suspension or levitation,

1. Electromagnetic Suspension.

2. Electrodynamic Suspension.

 A third type of levitation, known an Inductrack, is also being developed in the United States.

.ELECTROMAGNETIC SUSPENSION SYSTEM(EMS)

 Electromagnetic Suspension or EMS is the first of the two main types of suspension used with Maglev. This suspension uses conventional electromagnets located on structures attached to the underside of the train; these structures then wrap around a T-shaped guiderail. This guiderail is ferromagnetic, meaning it is made up of such metals as iron, nickel, and cobalt, and has very high magnetic permeability. The magnets on the train are then attracted towards this ferromagnetic guiderail when a “current runs through the guiderail and the electromagnets of the train are turned on”. This attraction lifts the car allowing it to levitate and move with a frictionless ride. “Vehicle levitation is analyzed via on board computer control units that sample and adjust the magnetic force of a series of onboard electromagnets as they are attracted to the guideway”.

The small distance of about 10mm needs to be constantly monitored in order to avoid contact between the train’s rails and the guiderail. This distance is also monitored by computers, which will automatically adjust the strength of the magnetic force to bring this distance back to around 10mm, if needed. This small elevation distance and the constant need for monitoring the Electromagnetic Suspension System is one of its major downfalls.

·                    

  Figure[4]

CR0SS SECTION OF ELECTROMAGNETIC SUSPENSION SYSTEM

The train also needs a way to stay centered above the guideway. To do this, guidance coils and sensors are placed on each side of the train’s structures to keep it centered at all points during its ride, including turns. Again, the gap should be around 10mm, so computers are used to control the current running through the guidance magnets and keep the gap steady. In addition to guidance, these magnets also allow the train to tilt, pitch, and roll during turns. To keep all distances regulated during the ride, the magnets work together with sensors to keep the train centered. However, the guidance magnets and levitation magnets work independently.

There are several advantages to this system. First, the train interlocks with the guiderail making it impossible to derail. Noise is extremely limited with this system because there is no contact between the train and its track. In addition, there aren’t many moving parts, which reduces the noise and maintenance of the system. With fewer parts, there is less wear and tear on the system. The Maglev train is also able to travel on “steep gradients and tight curves”. Figure [4] shows the metal beams which attach to the underside of the train. An example of Electromagnetic Suspension is shown in Figure [5] below. Before a Maglev system can be made, a choice must be made between using this type of suspension or Electrodynamic Suspension.

·                    

  Figure [5]

PHOTOGRAPH OF MALEV TRAIN(EMS)

.ELECTRODYNAMIC SUSPENSION SYSTEM

The second of the two main types of suspension systems in use is the Electrodynamic Suspension (EDS). EDS uses superconducting magnets (SCM) located on the bottom of the train to levitate it off of the track. By using super cooled superconducting magnets, the electrical resistance in superconductors allows current to flow better and creates a greater magnetic field. The downside to using an EDS system is that it requires the SCMs to be at very cold temperatures, usually around 5 K (-268ºC) to get the best results and the least resistance in the coils. The Japanese Maglev, which is based on an EDS system, uses a cooling system of liquid nitrogen and helium.

To understand what’s really going on here, let’s start from the inside out. The first major difference between EDS and EMS is the type of track. Whereas with EMS the bottom of the train hooks around the edges of the track, an EDS train literally floats on air.

THE ELECTRODYNAMIC SUSPENSION SYSTEM

The outside guides act like the cushions used to prevent gutter balls in bowling only an EDS train has a magnetic safety net to keep the train centered, unlike your traditional bowling ally. If the train is knocked in the horizontal direction, the field on the side it shifts to becomes greater and the field on the opposite side weakens due to this increase in distance. Therefore, in order to restore equal magnetic forces from each side, the train is pushed back into the center of the guideway and the strength of the magnetic fields reduces to their normal strength. This is one reason why EDS is a much more stable suspension system. A second reason why the Electrodynamic Suspension system is more stable is that it is able to carry a much heavier weight load without having its levitation greatly affected. As the gap between the train and vehicle decreases, forces between the SCMs located on the train and the magnets on the track repel each other and increase as the train gets heavier. For example, if weight is added to the train, it is going to want to get closer to the track; however it cannot do so because repulsion forces grow stronger as the poles on the train sink closer to the similar poles on the guideway. The repulsive forces between the magnets and coils lift the train, on average, about 4 to 6 inches above the track, which virtually eliminates any safety issues regarding the train losing levitation and hitting its guideway.  This brings us to the next thing we encounter as we move out from the center of the guideway. Levitation coils repel the SCMs underneath the train, providing the restoring forces to keep the train aligned.

Propulsion coils are located next. The propulsion system of the Electrodynamic Suspension system is quite similar to Electromagnetic propulsion, but does vary slightly. To propel the train, the guideway has coils running along the top and bottom of the SCMs. Induced current within these coils creates alternating magnetic fields that attract or repel the SCMs, sending the train in the forward or reverse direction. Because the trains are moving by magnetic waves that push and pull it forward, it’s virtually impossible for trains to collide since they are in essence “riding the same magnetic waves”.

No engine or other power source is required to keep the train moving except the initial speed that is required to begin levitation. Therefore wheels are required to keep the train moving until about 100 km/hr (65 mph) where it can then begin to levitate.

Finally, the guideway has rails that encompass the outside of the train. Within these rails are the propulsion coils and levitation coils needed to keep the train moving and levitating above the bottom of the track. Because the train has its own safety net of magnetic force to keep it centered, the rails simply provide a place for other coils to be located and used. This railway provides no other means of support for the train since the bulk of the train is floating above the entire track.

EDS suspension has several positive and negative aspects to it. To begin, initial costs are high and most countries do not have the money or feel the need to spend it on this kind of transportation. Once up and running however, an EDS Maglev runs only on electricity so there is no need for other fuels. This reduction in fuel will prove to be very important to the sustainability of Maglev. One huge disadvantage of the EDS system is the great cost and inconvenience of having to keep the super cooled superconductive magnets at 5K. Another drawback is that in the event of a power failure, a Maglev train using EDS would slam onto the track at great speeds. This is a second reason for the wheels that are primarily used to get the train moving quickly enough for levitation. The wheels would need to have a shock system designed to compensate for the weight of the car and its passengers as the train falls to the track. In Japan, where EDS Maglev is in its testing stage, trains average about  300 km/hr and have been clocked at 552 km/hr, which is a world record for rail speed. Compared to Amtrak trains in the United States, which travel at an average of        130 km/hr, Maglev can get people where they need in about half of the time. The EMS and EDS suspension systems are the two main systems in use, but there is a possibility for a third to soon join the pack.

A NEW TRACK IN THE RUNNING

Engineers are constantly trying to improve on previous technology. Within the past few years the United States has been developing a newer style of Maglev called the Inductrack, which is similar to the EDS system. This system is being developed by Dr. Richard Post at the Lawrence Livermore National Laboratory. The major difference between the Inductrack and the Electrodymanic System is the use of permanent magnets rather than superconducting magnets.

This system uses an “arrangement of powerful permanent magnets, known as a Halbach array, to create the levitating force”. The Halbach array uses high field alloy magnetic bars. These bars are arranged so the magnetic fields of the bars are at 90º angles to the bars on either side, which causes a high powered magnetic field below the array.

The Inductrack is similar to that of the EDS system in that it uses repulsive forces. The magnetic field of the Halbach array on the train repels the magnetic field of the moving Halbach array in the guideway. The rails in the system are slightly different. The guideway is made from “two rows of tightly packed levitation coils”. The train itself has two Halbach arrays; one above the coils for levitation and the other for guidance. As with the EMS and EDS system, the Inductrack uses a linear synchronous motor. Below is a picture of the Halbach array and a model of the Inductrack system.

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   Figure [6]

MODEL OF THE INDUCTRACK

A major benefit of this track is that even if a power failure occurs, the train can continue to levitate because of the use of permanent magnets. As a result, the train is able to slow to a stop during instances of power failure. In addition, the train is able to levitate without any power source involved. The only power needed for this system is for the linear synchronous motor and “the only power loss that occurs in this system is from aerodynamic drag and electrical resistance in the levitation circuits”.

Although this type of track is looking to be used, it has only been tested once on a 20-meter track. NASA is working together with the Inductrack team to build a larger test model of 100 meters in length. This testing could eventually lead to a “workable Maglev system for the future”. The Inductrack system could also be used for the launching of NASA’s space shuttles. The following picture displays side by side all three types of levitation systems.

LATERAL GUIDANCE SYSTEMS

The Lateral guidance systems control the train’s ability to actually stay on the track. It stabilized the movement of the train from moving left and right of the train track by using the system of electromagnets found in the undercarriage of the MagLev train. The placement of the electromagnets in conjunction with a computer control system ensures that the train does not deviate more than 10mm from the actual train tracks.

The lateral guidance system used in the Japanese electrodynamic suspension system is able to use one “set of four superconducting magnets” to control lateral guidance from the magnetic propulsion of the null flux coils located on the guideways of the track as shown in Fig.[10]. Coils are used frequently in the design of MagLev trains because the magnetic fields created are perpendicular to the electric current, thus making  the magnetic fields stronger. The Japanese Lateral Guidance system also uses a semi-active suspension system. This system dampens the effect of the side to side vibrations of the train car and allows for more comfortable train rides.  This stable lateral motion caused from the magnetic propulsion is a joint operation from the acceleration sensor, control devive, to the actual air spring that dampens the lateral motion of the train.

The lateral guidance system found in the German transrapid system(EMS) is similar to the Japanese model. In a combination of attraction and repulsion, the MagLev train is able to remain centered on the railway. Once again levitation coils are used to control lateral movement in the German MagLev suspension system. The levitation coils are connected on both sides of the guideway and have opposite poles. The opposites poles of the guideway cause a repulsive force on one side of the train while creating an attractive force on the other side of the train. The location of the electromagnets on the Transrapid system is located in a different side of the guideways. To obtain electro magnetic suspension, the Transrapid system uses “the attractive forces between iron-core electromagnets and ferromagnetic rails.” In addition to guidance, these magnets also allow the train to tilt, pitch, and roll during turns. To keep all distances regulated during the ride, the magnets work together with sensors to keep the train centered.

.ADVANTAGES AND LIMITATIONS OF MAGLEV

ADVANTAGES

Magnetic Fields

·          Intensity of magnetic field effects of Maglev is extremely low (below everyday household devices)

·          Hair dryer, toaster, or sewing machine produce stronger magnetic fields

Energy Consumption

·          Maglev uses 30% less energy than a highspeed train traveling at the same speed. (1/3 more power for the same amount of energy)

Speed	ICE Train	Maglev Train
200 km/hr	32 Wh/km	32 Wh/km
250 km/hr	44 Wh/km	37 Wh/km
300 km/hr	71 Wh/km	47 Wh/km
400 km/hr	-	71 Wh/km

Noise Levels

·          No noise caused by wheel rolling or engine

·          Maglev noise is lost among general ambient noise

·          At 100m - Maglev produces noise at 69 dB

·          At 100m - Typical city center road traffic is 80 dB

Vibrations

·          Just below human threshold of perception

Power Supply

·          110kV lines fed separately via two substations

Power Failure

·          Batteries on board automatically are activated to bring car to next station

·          Batteries charged continuously

Fire Resistance of vehicles

·          Latest non-PVC material used that is non-combustible and poor transmitter of heat

·          Maglev vehicle carries no fuel to increase fire hazard

Safety

·          20 times safer than an airplane

·          250 times safer than other conventional railways

·          700 times safer than travel by road

·          Collision is impossible because only sections of the track are activated as needed. The vehicles always travel in synchronization and at the same speed, further reducing the chances of a crash.

Operation Costs

·          Virtually no wear. Main cause of mechanical wear is friction. Magnetic Levitation requires no contact, and hence no friction.

·          Components normally subjected to mechanical wear are on the whole replaced by electronic components which do not suffer any wear

·          Specific energy consumption is less than all other comparable means of transportation.

·          Faster train turnaround time means fewer vehicles

LIMITATIONS

There are several disadvantages with maglev trains. Maglev guide paths are bound to be more costly than conventional steel railways. The other main disadvantage is lack with existing infrastructure. For example if a high speed line

between two cities it built, then high speed trains can serve both cities but more importantly they can serve other nearby cities by running on normal railways that branch off the high speed line. The high speed trains could go for a fast run on the high speed line, then come off it for the rest of the journey. Maglev trains wouldn't be able to do that, they would be limited to where maglev lines run. This would mean it would be very difficult to make construction of maglev lines commercially viable unless there were two very large destinations being connected. Of the 5000km that TGV trains serve in France, only about 1200km is high speed line, meaning 75% of TGV services run on existing track. The fact that a maglev train will not be able to continue beyond its track may seriously hinder its usefulness.

A possible solution

Although it is not seen anywhere a solution could be to put normal steel wheels onto the bottom of a maglev train, which would allow it to run on normal railway once it was off the floating guideway.

.CONCLUSION

           Railways using MagLev technology are on the horizon. They have proven to be faster than traditional railway systems that use metal wheels and rails and are slowed by friction. The low maintenance of the MagLev is an advantage that should not be taken lightly. When you don’t have to deal with the wear and tear of contact friction you gain greater longevity of the vehicle. Energy saved by not using motors running on fossil fuels allow more energy efficiency and environmental friendliness.

            Maglev will have a positive impact on sustainability. Using superconducting magnets instead of fossil fuels, it will not emit greenhouse gases into the atmosphere. Energy created by magnetic fields can be easily replenished. The track of a Maglev train is small compared to those of a conventional train and are elevated above the ground so the track itself will not have a large effect on the topography of a region. Since a Maglev train levitates above the track, it will experience no mechanical wear and thus will require very little maintenance.

            Overall, the sustainability of Maglev is very positive. Although the relative costs of constructing Maglev trains are still expensive, there are many other positive factors that overshadow this. Maglev will contribute more to our society and our planet than it takes away. Considering everything Maglev has to offer, the transportation of our future and our children’s future is on very capable tracks.

.REFERENCES

Þ       Sawada, Kazuo, "Magnetic Levitation (Maglev) Technologies 1. Supderconducting Maglev Developed  by RTRI and JR Central", Japan Railway & Transport Review, No. 25, 58-61.

Þ       He, J. L., Coffey, H. T., Rote, D.M. "Analysis of the Combined MagLev Levitation, Propulsion, and Guidance System", IEEE Transactions on Magnetics, Vol 31, No. # 2, March 1995, pp 981-987.

Þ       Zhao, C. F., Zhai, W. M., "MagLev Vehicle/Guideway Vertical Random Response and Ride Quality", Vehicle System Dynamics, Vol 38, No # 3., 2002, pp 185-210.

Þ       Cassat, A., Jufer, M. "MAGLEV Projects Technology Aspects and Choices", Transactions on Applied Superconductivity, Vol 12, No. # 1, March 2002, pp 915-925.

Þ       Powell, J., Danby G. “Maglev: The New Mode of Transport for the 21st Century” 21st Century Science & Technology Summer Issue.  http://www.21stcenturysciencetech.com/articles/Summer03/maglev2.

Þ       Lever, J. H. “Technical Assessment of Maglev System Concepts”, Final Report by the Government Maglev System Assessment Team.

Þ       Bellis, M. http://inventors.about.com/library/inventors/blrailroad.htm

Þ       Freeman, R.  http://members.tripod.com/~american_almanac/maglev.htm.

Þ       The Monorail Society Website Technical Pages http://www.monorails.org/tMspages/TPMagIntro.html

Þ       Seminar topics from www.edufive.com/seminartopics.html

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