Compressed air - Page 1 - The Pie & Piston Archive

Right, any idea what sort of pressure its at then?

I'm doing a tutorial question on a jet engine and i got a value of 17kg/m^3 for the density of air leaving a centrifugal compressor in model jet engine and i was wondering if it was a reasonable value.

GreenV8S

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Monday 7th March 2005

Sorry, that's a more complicated question. Your answer implies a compression ratio of 17:1 which seems reasonable. But you're dealing with adiabatic compression so the temperature will be way up; this will raise the pressure even further. (If you know about isothermal/adiabatic compression then you can work it out from here; if you don't, this probably isn't the approach they intend you to take.)

Sorry, adiabatic not isothermal. Engage brain next time!

>> Edited by GreenV8S on Monday 7th March 22:11

Chicane

Original Poster

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Monday 7th March 2005

GreenV8S said:
Sorry, that's a more complicated question. Your answer implies a compression ratio of 17:1 which seems reasonable. But you're dealing with isothermal compression so the temperature will be way up; this will raise the pressure even further. (If you know about isothermal/adiabatic compression then you can work it out from here; if you don't, this probably isn't the approach they intend you to take.)

I calculated the density using the temperature at the compressor exit and the pressure. I used the relation, P = rho*R*T where R is the specific gas constant.

I have decided it is reasonable enough!

Thanks for your help.

rude-boy

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Tuesday 8th March 2005

Hey up!

It’s the first thread that I have ever seen on here that requires you to be a rocket scientist to understand the answer!