A Decoupled Methodology to Fluid-Thermal Interaction in High-Speed Flow of Missile with Convection Boundary Condition

In high-speed fluid-thermal coupling problems, the accuracy of the solution largely depends on the frequency of information transfer at the solid-fluid interface. Whereas monolithic approaches and strongly coupled schemes offer some of the most accurate solutions, they are computationally expensive, particularly during the preliminary design phase, unlike decoupled methodologies. Hence, in the present study, a decoupled methodology is developed to shorten the global runtime for calculating the transient temperature distribution all through a missile skin during high-speed flight while maintaining accuracy. Given the strongly coupled nature of the problem, the present methodology aims to reduce inaccuracies and additional errors by using two approaches: The first is the usage of the convection heat transfer coefficient (HTC) as a thermal boundary condition on the solid subdomain since it exhibits a weak coupling with the wall temperature. The HTC distribution is obtained using the Modified Newtonian Law after conducting a series of flow analyses, the outputs of which are superimposed. The second approach involves selecting the value of constant wall temperature in the flow analyses close to the recovery temperature, attempting to simulate the effect of wall temperature on air properties to closely resemble real-world conditions. The radiative heat transfer mode, which plays a critical role during high-speed flight with the high outer surface temperatures, is incorporated into the solution. The global runtime is also shortened by employing a quasi-transient approach. The comparison is made with a 15° cone-cylinder-flare configuration rocket and a modified von Karman nose shape rocket from the literature, representing the high-supersonic and the hypersonic flow regimes, respectively, as well as with a Surface-to-Air missile flying in the high-supersonic regime. All show good agreement, with maximum and average discrepancies of 6.5% and 3.9%, respectively.