I assume that at some point giggling engineering students caused their instructor to change "turbine inlet temperature" from TIT to TET, but I wonder if anyone knows the real reason and history? Perhaps adapted from another language?
The temperature in jet engine turbines is usually measured in one (or more) of these places:
- Behind the combustion chamber at the turbine inlet: Turbine Inlet Temperature (TIT)
- Between low and high pressure turbine: Interstage Turbine Temperature (ITT)
- Behind the last turbine stage: EGT (Exhaust Gas Temperature) or TOT (Turbine Outlet Temperature)
As far as I know, TET is not used as an acronym for Turbine Inlet Temperature, where TIT is used.
There are however two different definitions for TET:
In gas turbines for power plants, TET stands for Turbine Entry Temperature and is defined in ISO 11086:1996 (Gas Turbines - Vocabulary).
It is very important for gas turbine calculations how the temperatures in the hot part of the gas turbine are defined:
- TIT - Turbine inlet temperature is defined as the temperature that would occur before the nozzle guide vanes, if all cooling air was mixed into the flue gases at that point.
- TRIT - Turbine rotor inlet temperature is the temperature before the first rotor stage, i.e. right before the work extraction begins.
- TET - Turbine entry temperature is the actual temperature before the nozzle guide vanes.
(Gas Turbine Cooling Modeling - Thermodynamic Analysis and Cycle Simulations by Kristin Jordal)
We have found that the turbine inlet temperature (TIT) or turbine exit temperature (TET) are viable parameters for indicating stall [...]
To avoid confusion, always check the glossary of the document when encountering TET. If there is no definition, it might be difficult to tell what the author meant.