Optimization of high-precision total enthalpy measurement method based on the total temperature probe

A kind of total temperature probe with Iridium Rhodium Iridium thermocouple is developed for improving the total enthalpy measurement accuracy. The size parameters of each component are optimized based on the fluid-thermal coupling model of the probe. The reheating rate of the probe is not less than 0.9 after optimization. The calculation and test results show that the temperature of the thermocouple node rises slowly as the temperature of the thermocouple tail and the shielding case rises. This fact results in the temperature of thermocouple node changing according to the measurement time period. So the measurement time period of the total temperature value should be regulated and the total temperature value must be calibrated. Therefore, a comparison calibration method is proposed, in which the total temperature probe used in the supersonic flow field can be traced to the standard calibration device in the subsonic flow field by an arc chamber total probe developed. Finally, the total enthalpy measurement test based on the total temperature probe is carried out in the arc heated wind tunnel. And the uncertainty of the total enthalpy measurement is calculated according to the uncertainty evaluation method based on the precision limit and deviation limit. The test results show that the total temperature probe has a high total enthalpy measurement accuracy. The repeatability precision is about 3% and the uncertainty is about 6.4% in this test.