Conjugate Heat Transfer Analysis in Hypersonic Applications
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Transient heat transfer analysis is highly essential for design of many engineering objects, such as steam and gas turbines, diesel engine blocks, jet engines, rocket motors, nuclear reactors etc. It is of significant priority and of scientific relevance to understand the flow in hypersonic applications. High aerodynamic heating rates associated with high-speed flights portray even more severe transient heat transfer problems for the design of spacecraft and missiles. In view of this Conjugate Heat Transfer (CHT), solver is used to understand the interface properties and flow properties due to change in wall heating rates. It is also useful to examine the heat penetration of solid in various wall materials with different time scales. Therefore the main focus of the present work is on the accurate prediction of heat transfer, temperature at the interface and flow properties. This problem is critically important in efficient design of thermal protection system (TPS) for hypersonic vehicles. TPS, in-fact is traditionally designed with the help of one-dimensional heat transfer analysis. Since, uncertainties are more in these studies; CHT is used to overcome those uncertainties. It is clear that thermal protection system can be optimally designed from these studies. The present investigations can be summarized in two main steps which are described as follows; Empirical analysis and numerical simulation. These are the two techniques generally used to estimate the surface heat flux in the above applications. In experimental analysis, the surface heating rates are predicted from the measured temperature by using one-dimensional heat transfer modeling and various methods like Laplace transform, Duhamel integral, Schultz and Jones methods. The temperature histories obtained from the in-house one-dimensional finite volume computation solver, literature reported shock tunnel measurement and supersonic flight experiment are used to predict the surface heat flux using fore mentioned methods. Heat flux recovery from all the methods for smooth temperature signals is seen to be in good agreement with reasonable accuracy of औ 5%. However, it has been noticed that the spline based fitting techniques supersede the polynomial based fitting techniques for prediction of heat flux from discontinuous or noisy temperature signals. Spline based fitting techniques are found to be precise for trend prediction and quantification of heat flux for all types of temperature data.
Supervisors: Vinayak N. Kulkarni and Niranjan Sahoo