Prediction and Experimental Measurement of Total Temperature in an Afterburning Turbojet Exhaust

摘要

A numerical model of an aspirated temperature probe with a vented shield placed in a flowing high-temperature stream has been used to assess the probe combined recovery factor in a subsonic combustion flow stream, and the results are compared to experimental data collected at the exhaust plane of an afterburning turbojet. Convection to the probe surfaces from a hot gas stream, radiation from the hot surfaces of the probe to space and to other surfaces in the probe, radiation from the gas surrounding the probe to the probe surfaces, and conduction in the probe are computed by the model. The model of the probe with no interaction with probe support consistently overpredicted the difference between the gas total temperature and the indicated temperature of the probe by about 50% for a temperature range of 800 to 1,400 K (1,500 to 2,500°R) in previous work. When an estimate of the heating of the probe supports is included, the difference was reduced to less than 10% over this range, and similar results are shown with comparisons using afterburning turbine engine exhaust measurements. The results suggest that the model provides good predictive results given adequate knowledge of the conditions of the measurement and that the model can be utilized as a tool for predicting combined recovery factors of high-temperature probes with vented radiation shields in a vitiated combustion environment.