The set up is similar to what Paul and I discussed
about 2 years ago and that was a high speed multi
gear PTO between the turbine and compressor.  We
abandoned it because of high gear line speeds and
the many shafts needed to get the ratio correct and
clear the turbine.

> Doug

In poking around on the subject of turbo compound
setups, I came across a technical paper that suggested
a good solution for transmitting the power extracted
by the turbine to other places (crank, compressor
wheel, etc.) without substantial concern about
potentially delicate and friction-prone multiple
shafts and gearsets.  In the example posited, they
coupled the turbine to a hydraulic pump.  The
pressurized hydraulic fluid could then be routed
wherever needed in hydraulic lines, and flutter in the
turbine or anything on the other end of the hydraulics
would be damped to a greater degree than in a purely
mechanical system.  It might lose a bit of efficiency
compared to a well-designed purely mechanical system,
but it looks on the surface to have a lot of practical
advantages.

Has anyone tried this before in any "outside the lab"
setting?  I'd be interested to see if that concept had
any merit for small aircraft (or perhaps even
road-going vehicle) turbo compounding.

Adam Wade


Well sort of in reverse. Garrett built a hydraulic motor boosted
compressor in a turbo charger intended for diesel engines.
Institute of Mechanical engineers paper C41/82 1982.

Diesel engines do not, on their own, accelerate well
as they are fuel throttled and not air throttled.
You speed them up by pouring more fuel in. Read richen them
up. Hence the black smoke. This was an attempt to speed them up
by pumping more air in as well as fuel.
It never saw production as far as I know. What did see production for
awhile was an electric motor assisted compressor. I am not
sure if that is still in production or what. Mazda built a hydrogen
burning rotary with an electric motor assisted compressor.
That may still be in limited  production in Japan.

The trend now is the variable vane turbo charger which
seems to be the simplest solution and most promising solution
for diesel engines and gas engines.

I would be interested in reading that paper Adam if you can scan
it in and email it to me.

Paul Lamar ...No rotor no motor.

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