Review of wave drag reduction techniques: Advances in active, passive, and hybrid flow control

Typical challenges of supersonic flight include wave drag, acoustic signature, and aerodynamic heating due to the formation of shock waves ahead of the vehicle. Efforts in the form of sleek aerodynamic designs, better propulsion systems, and the implementation of passive and active techniques are generally adopted to achieve a weaker shock wave system. Shock reduction can improve flight range, reduce fuel consumption, and provide thermal protection of the forebody region. This paper briefly reviews shock reduction techniques, including passive, active, and hybrid flow control. Airfoil shape optimization, mechanical spike, and forebody cavities are studied as passive flow control approaches. For active flow control, developments in the area of opposing jets and energy deposition are explored. The combination of active and passive flow control and the hybrid flow techniques are discussed in the end. The discussions include the principle of operation, physics of fluid behavior, and overall contribution to flight stability characteristics. The implications in the usage of these technologies, along with potential gaps, are also identified. This comprehensive review can serve as the basis for contemporary solutions to realize sustainable supersonic travel for the aviation industry.