We talked about turbochargers, superchargers and turbocompound engines.
You'll be pleased to know that I've found an engine that uses all three
(!). It's the Napier Nomad. I haven't found a really good description
online, but I do have a magazine article about it. I'll scan a drawing
tomorrow.
The Nomad 1 is a 12-cylinder, two-stroke diesel that drives one
propeller of a counterrotating combo. Its exhaust contains an
afterburner (!), and a turbine.
That turbine drives a compressor [1], plus the second propeller.
The engine's crankshaft also drives a supercharger (located after the
compressor [1] and an intercooler.
Oh, and the engine had bypass ducts around the intercooler, afterburner,
and half the stages of the exhaust turbine, so you could drive the
engine in numerous configurations.
<
http://www.chrishodgetrucks.co.uk/pixww/2002Wroughton23.jpg>
<
http://www.wikipedia.org/wiki/Napier_Nomad>
Alas, it never reached production.
And now for the 'random trivia' section:
- About 10% of a Merlin's power was actually thrust from the exhaust
pipes.
- RR once designed an engine that was supposed to generate 30% of its
power this way (the Crecy). It wasn't successful - using that energy to
drive a turbocharger proved to produce more power. And less noise: the
Crecy opened its exhaust valves very early, while the fuel mixture was
still burning. During tests, the engine could be heard 25 km from the
workshop. In comparison, a Griffon was quiet.
- The Lycoming XR-7755 (a 36-cilinder, 127-litre, 5000-bhp radial) was
even louder than the Crecy. Concrete walls around the test bench
actually crumbled under the noise.
- The turbo-compound version of the Wright R-3350 used 20% less fuel to
produce 700 bhp more.
- <
http://www.nasm.edu/features/qtvr/uhc/artifacts.htm>
--
Harro de Jong
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