SURFACE JUNCTION TEMPERATURE PROBE FOR SHOCK TUBE FLOWS
Estimation of the surface heating rate from the transient temperature data is one of the very important aspects of many scientific and engineering types of research. Considering the case of high-speed flow environment, the timescale of application is very small of the order of few milliseconds. With the use of appropriate one-dimensional heat conduction modelling, the surface heat flux is predicted from the obtained temperature-time histories. It is essential to have a closed form solution of the obtained temperature histories, for performing analytical modelling. The present work focuses on analyzing the transient temperature data in order to infer surface heating rate. The temperature histories are obtained from the experiments conducted on the in-house fabricated shock-tube. The experiment is mainly repeated for two different cases, once with coaxial surface junction thermocouple mounted on the end flange and other with coaxial surface junction thermocouple flush mounted on the hemisphere fitted at the end-flange. Three different discretization techniques namely, piecewise linear fit, polynomial (least square), and cubic-spline fit, are employed in order to recover the temperature histories. A one-dimensional heat conduction modelling is utilized in order to obtain closed-form solution of the obtained data. The obtained results have shown a satisfactory trend. However, with CSJT mounted on the hemispherical, least square techniques slightly underpredicts the peak value.