Numerical simulation of the flow in a sensor for measuring the flow stagnation temperature in pulsed aerodynamic installations

This paper describes a problem of measuring a gas flow temperature using thermocouples for which the time it takes to reach an equilibrium temperature is shorter than the duration of the measurement process. Results for the numerical simulation of a gas flow in a sensor used to measure a stagnation temperature in short-term wind tunnels are presented. The conjugate problem of a sensor in a supersonic flow is solved and the flow field inside the stagnation chamber is calculated. The temperature of the thermocouple place at the end of the stagnation chamber is determined. The results of simulating the thermocouple readings depend on time and the oncoming flow parameters. The obtained readings of the stagnation temperature sensor are taken as virtual experiment data, which are processed using experimental aerodynamics methods. The “step process” and “two thermocouples” methods are used to restore the stagnation temperature. A difference in thermocouple readings is a normalized thermocouple hardware function. True temperature readings are restored by deconvolution. The restored readings are compared with the initial values of the stagnation temperature in the incoming flow to the sensor. The sources of measurement errors are determined, and the applicability of experimental methods for determining the stagnation temperature in short-term aerodynamic installations, including those with parameters decreasing with time, is substantiated.