barit1
In a way it is a misnomer because the EGT reading doesn't come from the exit end of the LPT like you would expect. I explained in a previous post why the thermocouples are located where they are in modern engines, e.g., inside the stage 1 LPT hollow vanes.
However it is an important engine diagnostic feature and one that is paid close attention to during engine design. The object in design is to design the greatest EGT margin possible, actual operation EGT verses maximum EGT at takeoff. The longer the margin can be maintained, the longer the engine can stay on wing and the healthier the rotor tip clearances and absence of blade tip wear is. Also, it can indicate the accumulation and build up of foreign material on the airfoil surfaces that reduces aerodynamic efficiencies. Water washing has become popular to restore EGT margins these days.
Turbine D