Comparison of Strategies for Coupled Flow-Thermal Analysis of Thermal Protection System at Hypersonic Flight Condition

Abstract

Coupled flow-thermal analysis is crucial for the performance evaluation and structural design of hypersonic vehicles. In this study, several strategies for computing the coupled flow-thermal response of air-breathing hypersonic flights in practical engineering are developed and compared. First, the basic direct correction method that amends wall heat flux via recovery temperature and wall temperature is proposed to approximate flow-thermal effects efficiently. Second, the improved DCM (IDCM) is further developed by interpolating the cold wall heat flux and the recovery temperature between adjacent trajectory points to improve computational accuracy. Third, the iteration solution method (ISM) that obtains solutions through mass and energy balances at a common interface by iterations between CFD analysis code and CSD analysis code is also presented. Thermal response and flow characteristics are compared through a test case of an air-breathing hypersonic vehicle. The results show that the thermal response tendencies are consistent by DCMs and ISM. However, for DCMs, the impact of hot wall on the flow characteristics is ignored, whereas it is fully considered in ISM; thus, the thickened boundary flow and complicated internal flow can be captured. However, while comparing computational efficiency, DCMs have a prominent advantage over ISM due to the decoupling algorithm and parallel strategy. Based on this, in the actual design process of an air-breathing hypersonic vehicle, the designers can select the proper flow-thermal analysis method according to the different design stages.