Performance assessment of thermoelectric detector for heat flux measurement behind a reflected shock of low intensity

Abstract

Abstract The study is devoted to assessing the applicability of the manufactured thermoelectric sensor for functioning in shock tubes to measure instantaneous heat fluxes occurring in shock-wave processes. The gas-dynamic parameters of supersonic and hypersonic flows in test sections of such facilities can be quite harsh due to high values of enthalpies. At the same time, the typical operating period in such experiments is several milliseconds, which imposes specific requirements on the instruments used for registering heat fluxes. Thermoelectric heat flux sensors have been constructed in-house. The sensitive element of the sensor is a thin film of artificially anisotropic chromium obtained by oblique deposition on a high-resistance silicon substrate. This technology is used in laser systems to measure the power of laser radiation. The results of experiments on the generation of low-intensity reflected shock waves in nitrogen are presented. The new thermoelectric detector was used to register the heat flux from a hot gas heated by a shock wave reflected from the end of the shock tube. At the same time, the heat flux was measured using a sensor based on anisotropic thermoelements with a known sensitivity. Experiments have shown that the sensor has a high speed (~1 μs), a high signal-to-noise ratio, and a high electrical signal. The results obtained demonstrate the applicability of the sensor for measuring convective heat flux in shock tube experiments.