Transient Heat Transfer Analysis on Coaxial Surface Junction Thermocouples of Types K, E, and J

Abstract

AbstractHeat transfer is paramount in the design of hypersonic vehicles. For a vehicle at hypersonic flight, it is arduous to precisely estimate the surface convective heat flux. A need has emerged, for fast responses in the measurement of transient temperature data, in such hostile hypersonic conditions, thus paving way for the development of thermal sensors like thin film temperature detectors and coaxial surface junction thermocouples, for various aerospace applications. Owing to the presence of high temperatures, the surface heat flux and temperatures cannot directly be measured at the surface. Inverse analysis is used to detect the heat flux, from the temperature measurements given by the sensors, placed beneath the surface. In this study, the transient temperature data is acquired from the models of coaxial surface junction thermocouples, of types K, E, and J, from thermal simulation. This data is suitably discretized and is subsequently used in recovering the convective heat flux. Validation of the numerical models of the thermocouples, is done using analytical methods, by retracting the heat flux supplied during the simulation. The obtained heat flux histories from the analytical methods are observed to be in close approximation to the given input heat load of 1000 and 5000 W/m2. The transient temperature histories generated from the numerical simulation, are found to be in-line with the experimental outcomes.KeywordsHypersonic vehiclesConvective heat fluxTransient temperature dataCoaxial surface junction thermocouples