Sometimes old ideas that have fallen out of favor become viable again
when the economic environment changes or there are some developments
in technology that change the balance back in their favor.
I think turbo compounding's time has come again.
Paul Lamar

Probably the most practical way to look at turbo compounding in auto
applications would be in a hybred vehicle. The turbine could drive a
 homopolar alternater at direct drive speeds to charge the electric
assist modes. This would uncouple the turbo rpm from drive shaft
rpm and avoid the complexity and losses of clutches and gears.
On an aircraft the weight and complexity of a hybred would be
excessive, but you could offload all accessories to the
electric system. - Vance J

Yes I was thinking that use in a hybrid would be rather a good
application. A small turbo compound all aluminum wankel engine
would save a bunch of size & weight over a small piston engine.
All you would need is a small alternator that would work at
100,000 RPM. Probably not that hard to do. As an intermediate
step one stage of gear reduction would probably work with
an off the shelf alternator.
Paul Lamar

"Michael D. Lilja" wrote:

I have been told by a couple of people as well as reading, one of the reasons the P-51 was so fast
and efficient (relatively) was that the thrust developed by the cooling system ducting was used to
offset the cooling system drag.  What if you used the energy of the exhaust to run a turbine wheel
in the manner of a jet engine and used the power generated to run a fan (in the manner of a turbo
fan engine.)  That would maybe not only create a higher density atmosphere for combustion (bleed
air form of turbo charging.)  Blow the rest of this air over all the radiators (oil and coolant)
and collect their heat energy.  Then in a concentric tube with the exhaust, duct it out the back
directly as thrust and skip the mechanical connection to the engine all together?  Might be
simpler and easier.  One of the draw backs I can think of would be fitting it in some where.  Just
remember, if you think it has some merit, you heard it here first!  :-)  Thanks for the wonderful
discussions and forum.  I am also glad to see someone else as interested in turbo compounding as
me.  Maybe these two attachments will give you some ideas as well.  The pictures are courtesy of
Torque Meter

Mike Lilja

Mike I took the liberty of substituting a better picture of the Napier Nomad
I had on file than the one you uploaded. Here is your drawing and
the Nomad picture in question. Too bad the Napier Nomad never went into
production. It was an outstanding turbo compound design.

Paul Lamar

 
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