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AdamFrisch
11th Nov 2014, 17:38
I was wondering if anyone knows what the temps are roughly in the compressor stage of let's say a RR 250-C20 type engine? That engine has an axial flow turbine before a centrifugal flow turbine and I'm most curious how the temps are in the initial or axial part of that design? Reason I'm asking is, if the temps are not that high, could you get away with carbon fibre blades and stators in this part?

lomapaseo
11th Nov 2014, 18:54
Stable temperatures are one thing, short time stagnation stall temperatures are quite another. Then there is the erosion at high velocities and the workaround costs.

I would have concerns about the ruggedness to withstand abnormalities without having to scrap the parts.

Vendee
11th Nov 2014, 18:55
I don't have any experience on that engine type but I would think you are looking at around 250 degrees C. The latter stages of an axial flow compressor are usually made with nickel alloys or titanium because of the heat.

pilot9248
11th Nov 2014, 19:03
Vendee, he's asking about typical temperatures in the axial stages i.e. stages 1 to 6 in a RR 250-C20B. You're correct though, a typical compressor outlet temperature is slightly above 250 degrees C.

Vendee
11th Nov 2014, 21:11
TTF, yes I know what he was asking ;)

Oktas8
11th Nov 2014, 22:18
I thought a key property of carbon fibre structures was flexibility - the ability to distort elastically under stress. In other words (http://www.engineeringtoolbox.com/stress-strain-d_950.html), a low Young's Modulus.

For reasons of compressor case clearance and precise aerodynamic control, I would have thought compressor rotor blades must have a very high resistance to tensile stress; a high Young's Modulus.

Stators, perhaps. You could use them in the early stages, even if the temps were too high in later stages.

TURIN
11th Nov 2014, 22:50
Is this what you are looking for?

Rolls-Royce RB162 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Rolls-Royce_RB162)