Eric Ruttan wrote:

<snip>

I haven?t read anything on a high compression rotary combustion chamber
shape.  What does it look like?  What is impractical about the higher
ratios?
As I understand it diesel BFSC's are a function of the BTU density AND the
high compression ratio.  At higher ratios we are able to extract more

energy

out of the burn.  This was figured out a long time ago by hot-rodders.

Wasn't there a few compression ignition rotary's?  How'd they work without

a

high compression ratio?

As you make the rotor depression shallower and shallower the combustion
chamber
becomes a long rectangular flat volume. This quenches the fire due to excess
heat loss to the rotor and rotor housing. The ideal combustion chamber
shape is a sphere.

Rolls Royce built a compression ignition rotary wherein two rotors were
used in a compound arrangement. One rotor pre compressed the air for the
second
rotor. I suspect it failed for the same reason a super charger or turbo
charger does not result in better BSFC. Too much heat loss.

Paul Lamar

Is there a reason a rectangular shape is necessary?  Would not one "well"
recessed in the rotor per injector be workable? This would mean two wells
and two "combustion chambers" that would merge into one as the rotor
rotated.

If you recessed a well in the rotor housing it would leak mixture or hot gases
from leading chamber to trailing chamber when the apex seal passed over it. PL

VW's combustion chamber is a cylinder recessed in the piston directly under
the injector.  It seemed such a thing could be done for each injector on the
rotary.

The shape we have now is a compromise.

Paul Lamar
 
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