Tegheim - Home made 4 rotor Wolvo 142

[infernosg]

Originally Posted by rgould

That I would agree with that on a modern-day turbine components but you also have to remember that modern-day turbines are cooled only by extra air being forced through the insides of the blades so the actual metal temp on a modern-day turbine components is a lot higher than the actual metal temp of a rotor witch is cooled on each rotor face by an intake charge of air and fuel and the internal side of the rotor has engine oil cooling it there by making the rotor more like a piston than a turbine component ( the turbine components never see a cool down cycle once its up and running )

No need to explain to me; I design turbine stators (we call 'em nozzles) for a living We actually use compressor bypass air to cool turbine components the "cooled" air is actually north of 1000F, typically.

Originally Posted by rgould

std egt for a race rotary are around 1600 to 2000 deg F
piston race engine 1400 to 1700 deg F pending on tune and application

That isn't as bad as I thought but still too high for Ti. From what I've seen 1000F is about the limit. In the turbine actual metal temperatures can get above 2000F, which is getting out of range for most traditional nickel-based alloys and then you've got to start getting into directionally solidified and single-crystal alloys with protective coatings...

Originally Posted by rgould

there are coatings that can be aplyied to the rotor for high-temperature oxidation and corrosion if that would be a problem

I'm familiar with your typical TBC's and environmental coatings on turbine components but not in compressors. In the aviation world compressor blades typically are bare Ti or have some kind of anti-abrasion coating.

Sorry to get OT but this is a good discussion.