Turbine engines, and particularly gas or combustion turbine engines, are rotary engines that extract energy from a flow of combusted gases passing through the engine onto a multitude of rotating turbine blades. Gas turbine engines have been used for land and nautical locomotion and power generation, but are most commonly used for aeronautical applications such as airplanes or helicopters. In airplanes, gas turbine engines are used for propulsion of the aircraft.
During operation of a turbine engine, the total air temperature (abbreviated TAT, and also known as stagnation temperature) can be measured by a specially designed temperature probe mounted on the surface of the aircraft or the interior walls of the turbine engine. The probe is designed to bring the air to rest relative to the aircraft; the air experiences an adiabatic increase in temperature as it is brought to rest and measured, and the total air temperature is therefore higher than the ambient air temperature. TAT is an essential input for calculating static air temperature and true airspeed.
Because TAT sensors are often mounted in front of the turbine engine, they can be exposed to adverse conditions including high Mach numbers and icing conditions, as well as water and debris, which may affect the reading provided by the sensor.