Most people think that turbo compound means that high back
pressure in the exhaust is generated. Not true. Maybe just a
little.

Turn your bicycle upside down and squirt the tire with
a garden hose equipped with a nozzle squirter.
Note; the tire spins at high RPM. If you had a blow down
turbine on the water pipe coming into your house
you could charge your batteries every time you flushed
the toilet.

The turbo compound works pretty much the same way.
The exhaust is several pounds of air moving at the speed
of sound roughly. The HP here is equivalent to half the total fuel
burned. Everybody that has ever heard a rotary run with
out a muffler can attest to this.

Now how do we get this HP back with out building a lot of back pressure
in the exhaust? Significant back pressure in the exhaust would reduce the
power of the basic engine.

We use a blow down turbine.

If the diameter of the turbine is 12 inches and
the circumference is 38 inches and the RPM is 8000 the blades
are moving 38 X 8000 304,000 inches per minute.

304,000 is 25,333 feet per minute

25,333 feet per minute
Is 25,333 / 5280 is 48 MPH blade speed

48 MPH is 70 feet per second blade speed

700 MPH (exhaust) is about 1000 feet per second air speed over
the blade. The angle between them is very near 90 degrees.

Due to the angle between exhaust direction and blade direction the
lift coefficient would be roughly one. Think of a wing moving through
the air at supersonic speed at a lift coefficient of one. LOTS OF LIFT.
This translates to lot of additional torque as the blade RPM is constant.

Despite one might thing, turbo charger work much the same way.

If you are using a so-called smart (stupid)  phone all these files (8)  may not show up.
Usually you will only see three.

Paul Lamar


The Rotary Engine free News Letter. 750 subscribers world wide.

ACRE NL web site. http://www.rotaryeng.net
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