Wankel Engine – Advantages , Disadvantages and Application
The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion.
All parts rotate consistently in one direction, as opposed to the common reciprocating piston engine, which has pistons instantly and rapidly changing direction 180 degrees. In contrast to the more common reciprocating piston designs, the Wankel engine delivers advantages of simplicity, smoothness, compactness, high revolutions per minute, and a high power-to-weight ratio. This is primarily because there are three power pulses per rotor revolution. In a two-stroke piston engine there is one power pulse per crankshaft revolution, with one in two revolutions in a four-stroke piston engine. Although at the actual output shaft of a rotary engine, there is only one power pulse per revolution, since the output shaft spins three times as fast as the actual rotor, as can be seen in the animation below, it makes it roughly equivalent to a two-stroke piston engine of the same displacement. This is also why the displacement only measures one face of the rotor, since only one face is working for each output shaft revolution.
Advantages Of Wankel Engine :
Advantages of Wankel Engine :
1.Wankel engines have several major advantages over reciprocating piston designs, in addition to having higher output for similar displacement and physical size. It is simple and has fewer moving parts.
2. The rotor is geared directly to the output shaft, there is no need for connecting rods, a conventional crankshaft, crankshaft balance weights, etc
3. Smoother flow of power but also the ability to produce more power by running at higher rpm.
4. Fuel of very low octane number can be used without preignition or knock.
5. It’s substantial safety benefit makes it useful in aircraft
6. There is no valve operation.
7. The engine is constructed with an iron rotor within a housing made of aluminum, which has greater thermal expansion. This ensures that even a severely overheated Wankel engine cannot seize.
8. It has smaller frontal area than a piston engine of equivalent power. The simplicity of design and smaller size of the Wankel engine also allows for savings in construction costs, compared to piston engines of comparable power output.
Disadvantages of Wankel Engine :
1 .The fuel-air mixture cannot be pre-stored as there is no intake valve.
2. Time available for fuel to be injected into a Wankel engine is significantly shorter.
3. More complicated fuel injection technologies are required.
4. In terms of fuel economy,Wankel engines are generally less efficient than four stroke piston engines
5. Sealing loss is high.
6. The compression ratio is lower. This lowers the thermal efficiency and thus the fuel economy.
7. It is difficult to expand the engine to more than two rotors.
8. There can be more carbon monoxide and unburned hydrocarbons in a Wankel’s exhaust stream.
9. Wankel engines are very sensitive to misfires since the engine will lose momentum from the lost stroke and get slammed back into movement fr om the next chamber firing. Care of the ignition system is of utmost importance to avoid the problem.
Applications of Wankel Engine:
1. Used in aircraft.
2. Racing car.
3. For mini, micro, and micro-mini engine designs.
4. The most exotic use of the Wankel design is in the seat belt pre-tensioner system of some Mercedes-Benz.
5. Go-karts, personal water craft and auxiliary power units for aircraft.
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