> Hi Paul and all
> > I thought one of the benefits of a electrical
> generator connected to a
> turbo shaft (save the efficiency losses associated
> with convertion to
> electrical and then back to machanical) might be
> doing away with the
> wastegate to govern turbine rpm and instead
> adjusting the load on the
> genertor elecrically thereby governing the rpm of
> the turbine.
> > Just thinking
> > Steve Izett
> Perth West Aust
> Glasair SII RG Renesis
> > A couple of problems. We are dealing with at least
> 30 HP here.
> 30 HP is 23 KW. One HP is equal to 746 watts.
> > A 23 Kw alternator is a big  and heavy alternator.
> At 12 volts that
> is 1916 amps!!!! That is a lot of amps.  At 36
volts
> it is still
> 638 amps. The solid state components necessary to
> deal with 638 amp
> alternating current  are  real expensive.
> > If we fed that into a 36 volt electric motor that
> would be a big
> and heavy electric motor. A starter motor is about
3
> HP for a short
> period of time until it over heats.
> > Now every time you convert mechanical HP to
electric
> HP there is some loss.
> > Lets say the eff. of the alternator is 85% and
> the eff. of the motor is 85%. The over all eff. of
> the system is
> 85% times 85% is 68%. We are throwing away 32% of
> our 30 HP or
> 9.6 HP and we are now down to 20.4 HP net.
> > It is best to stick to mechanical HP when ever
> possible.
> > Paul Lamar ...No rotor no motor.


I'm about as far from being an engineer as a
hombuilder can be, but I would think that you'd want
to keep the turbo compound as simple as possible. So
wouldn't the best solution be to have the turbine
wheel mounted on the flywheel/ flexplate in between
the engine and redrive. It would take some testing
to
find the optimum exhaust diameter(flow speed,
turbine
wheel diameter) you might be able to make the wheel
a
smaller diameter if the diameter of the exhaust were
made bigger- say 3 inches. You'd have a lower
pressure/slower exhaust flow  exerting it's force
over
a larger area.  A 24 inch diameter turbine might be
the optimum size, but would be a bit hard to fit
into
an RV-4.

Brian Trubee

Thinking a bit more about this, I guess, that my
scheme(smaller, fatter turbine wheel would result in
less torque at at slower RPM, not a good recipe to
capture the most energy from the exhaust. But I sure
hope someone goes ahead and develops the concept.

Brian Trubee


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