Numerical Study on Low-Temperature Region as Heat Sink and Its Heat Dissipation Capacity for Hypersonic Vehicle

Researches have focused on the thermal protection system (TPS) of hypersonic vehicles under severe aerodynamic heat. According to the second law of thermodynamics, heat transfer needs to consume a heat sink, but the cold energy provided by the airborne heat sink is limited. Therefore, it is necessary to explore new available heat sinks during hypersonic cruise. This paper numerically calculated the wall temperature distribution of hypersonic vehicle X-51A with different Mach numbers, altitudes and angles of attack using ANSYS Fluent 19.0. A dimensionless parameter, relative temperature coefficient rt, was proposed to characterize the relative value of local wall temperature in the whole wall temperature range. The distribution regularity and influencing factors of wall temperature were summarized. The low-temperature region which is less affected by flight conditions was divided as the heat sink and its heat dissipation capacity (Q) and characteristics were studied. The angle of attack has great influence on the temperature distribution. In XY view the rear side of leeward surface is least affected by flight conditions and its rt is less than 0.2, which can be used as a low-temperature region. Taking this region as a heat sink to dissipate heat, it is found that the Q of the new heat sink is 30 kW/m2 at Ma 3, 90 kW/m2 at Ma 4 and 200 kW/m2 at Ma 5. The Q increases greatly with the increase in Mach number, and the convective heat transfer coefficient (h) also increases. At the same Q, the h decreases with the increase in Mach number. The exploration of low-temperature region as heat sink has an important reference for reducing the dependence on consumable heat sink and alleviating the energy shortage of the hypersonic vehicle.