Stagnation and Bulk Mean Temperature

Abstract

Earlier we have described various methods of temperature measurement. We have also discussed the measurement of temperature of a moving fluid, essentially at low velocities. However, when flow velocities of a gas are high (as, for example, in high subsonic or supersonic flows) the temperature of the gas under stagnation conditions is higher than the temperature of the moving gas because of conversion of kinetic energy to internal energy. The gas temperature takes on a value that is referred to as the stagnation temperature. The stagnation temperature is the same regardless of whether the process through which the stagnation process takes place is reversible or irreversible, as long as it is adiabatic. In many engineering application, it is essential to measure the stagnation temperature. We shall consider two different probes that may be used for this purpose.