An Active Interfacial Drag- and Heat-Reduction Technique Based on a Windward Concave Cavity Design: Reverse Jetting

The airflow velocity at the solid–air interface is directly proportional to the generated drag and heat. Therefore, reducing drag and heat at such interfaces under extreme operating conditions (e.g., supersonic flight) is particularly important. In contrast to the passive drag-reduction technique, which cannot significantly reduce drag and heat, in this study, an active interface drag- and heat-reduction technique based on a windward concave cavity (reverse jet) is presented. The effect of the number of jet holes, their relative position, size, and other parameters on the drag and heat at 6.5 Mach is investigated using the FLOEFD simulation software. The results show that a five-hole cross-distributed jet achieves the best thermal protection: the total surface static pressure, drag, and surface temperature are reduced by 51.7%, 33.9%, and 31.2%, respectively, compared with the case without a reverse jet. This study provides guidance for the structural design of thermal protection and drag-reduction systems.