MadSci Network: Science History |
Paripurnachari, That's a very good question: in theory, the Wankel rotary engine is a very simple, efficient machine that can produce a higher power output per unit engine weight than the more common Otto/Benz reciprocating-piston engine design, but the only major manufacturer of that design was the Mazda motorcar company. Despite theoretical advantages, the Wankel design has several technical hurdles that have made it less attractive than the Otto. First, the Wankel design requires rotating seals, both between the rotor faces and the rotor outputs. These are harder to design and to maintain, so Wankel engines have had a tendency to have lower compression pressures than Otto engines, which lowers the power available from the engine. Second, while the Wankel design has better fuel-air mixing and more even combustion in the chamber, it has a larger fraction of unburned fuel after each power cycle than a reciprocating piston engine with the same combustion-chamber size. That unburned fuel reduces the efficiency of the engine. Third, it is very difficult to make a Wankel engine with more than two rotors because they all have to synchronize directly with the rotating power shaft. Additional rotors mean additional power can be produced by the engine, just as additional pistons mean additional power in a reciprocating engine. Some racing car designers have managed to do this, but at the cost of additional sealing and coupling structures that dramatically increase the complexity and weight of the engine. A good animation of a Wankel engine in action can be found at http://www.keveney.com/Wankel.htm l . Discussion of the Wankel engine and its advantages and disadvantages can be found at http://www.monito.com/wankel/r ce.html and also at http://en.wikipedia.org/w iki/Wankel_engine . I hope you find these helpful. Thanks again for the question!
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