Measurement of the gas flow stagnation temperature by the method of two identical thermocouples in the short-duration aerodynamic facilities

Investigations of the temperature and heat flux distributions over the external surface of flying vehicles are important for the development of hypersonic planes. For obtaining correct results, experiments are performed in short-duration high-enthalpy wind tunnels. Determination of the stagnation temperature of the flow in such facilities is a challenging task due to short start-up times and high flow temperature. In this paper a new method is proposed for determining the stagnation temperature of a gas flow in the short-duration aerodynamic wind tunnels with stepwise changes in its parameters. The method is based on using two identical thermocouples with different initial temperatures. It is shown that in the case of jump-like changes in flow parameters the instrument function of the difference of the thermocouple readings coincides with the instrument function of each thermocouple, and the instrument function itself is actually the normalized temperature difference. The instrument function obtained in the study allows temperature retrieval by the method of deconvolution. This approach is highly sensitive to random noise of experimental data; therefore, regularization methods are applied for high-frequency noise suppression. A procedure for choosing the regularization parameter for temperature reconstruction is proposed. The research novelty of the article is that the proposed method allows exact reproduction of the stepwise function and instrument function without any additional assumptions, while the measurements and dynamic calibration are performed in one experiment. Applicability of the method for obtaining the stagnation temperature in the short-duration high-enthrall wind tunnel IT-302 M ITAM SB RUS is demonstrated. [Display omitted] •Proposed a new method of stagnation temperature measurement in hotshot wind tunnels.•Method is based on deconvolution of two thermocouples measurements in one run.•Procedure of thermocouple instrument function definition is offered.•Method applicability is shown in high-enthalpy wind tunnel at temperatures 400–1200 K