Multi-faced rotary

[InsanityInc]

While rotary engines have great hp/liter ratings, they lose out in fuel efficiency big time. Now, it seems to be common wisdom that the reason for the fuel inefficiency is due to the large SA:V ratio of the combustion chamber, since the rotor face is rather large, especially when compared to a piston. So, in order to reduce that surface area, would it be possible to make a rotor that had many more than 3 faces, so that each combustion chamber formed by the rotor has a much smaller SA:V?

 

[tbuelna]

The Wankel rotary's lower efficiency is due to many issues besides unfavorable surface area/volume ratios within its working chamber. For example, it also has a much greater seal line length exposed to combustion pressures, producing higher friction loss.

I have not seen details of what you propose, but in general, increasing the number of working chambers without increasing total engine displacement, will make the surface area/volume situation worse, not better.

Good Luck.

 

[dgallup]

Probably the biggest efficiency problem is the low expansion ratio of the rotary. WAY too much energy goes straight out the exhaust port.

 

[patprimmer]

How is the expansion ratio of a rotary intrinsically different to a piston engine.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[bettonracing17]

Related reading:

http://quasiturbine.promci.qc.ca/