EPR against TGT
Thread Starter
Joined: Aug 2006
Posts: 5
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From: Hong Kong
Originally Posted by KennethTang
Hi all,
anyone knows the actually relationship between EPR and TGT for a gas turbine engine?
any equation or formula to relate them?
Please help!!
anyone knows the actually relationship between EPR and TGT for a gas turbine engine?
any equation or formula to relate them?
Please help!!
Joined: Sep 2002
Posts: 2,188
Likes: 6
From: La Belle Province
There is no single relationship. Each type of engine will be different (even those which dont use EPR as a control parameter have an EPR, they just dont bother displaying it), and each individual engine will be subtly different from its kin, and each individual engine will have a different TGT/EPR relationship as it ages.
Other than "EPR and TGT usually increase and decrease together" there's no real answer to your question.
Other than "EPR and TGT usually increase and decrease together" there's no real answer to your question.
Joined: Feb 2005
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From: flyover country USA
Joined: Sep 2003
Posts: 26
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From: The Mercury Project
Part of EPR is measured at the same place as TGT. There's a thermodynamic relationship between the temperature of the gas stream and the pressure at the 4.5 station of the engine (where TGT, ITT, TOT, T5 etc is measured in modern jet engines). Put simply, more fuel goes into the burner can, it combusts thus increasng the engergy of the gas stream accelerating it. This energy is taken out of the gas stream as faster turbine speed and increased engine power. You'll see a rise in EPR and TGT and they're separated by (in very round terms) a constant (with some standard assumptions) that I can't recall right here and now. Sorry for the vagueity (if that's not a word I hereby claim it on behalf of the test community) but I don't have my references near to hand.
LGC
LGC
