In this research paper, investigations of counter flow (opposing) jet on the aerodynamic performance, and flight stability characteristics of an airfoil with blunt leading-edge in supersonic regime are performed. Unsteady Reynolds-Averaged Navier-Stokes ( U R A N S ) based solver is used to model the flow field. The effect of angle of attack ( α ), free-stream Mach number ( M ∞ ), and pressure ratio ( P R ) on aerodynamic performance of airfoil with and without jet are compared. The results indicate that the opposing jet reduces drag from 30 % to 70 % , improves the maximum lift-to-drag ratio from 2.5 to 4.0, and increases shock stand-off distance from 15 % to 35 % depending on flow conditions. The effect of opposing jet on longitudinal flight stability characteristics, studied for the first time, indicate improvement in dynamic stability coefficients ( C m q + C m α ˙ ) at low angles of attack. It is concluded that the opposing jet can help mitigate flight disturbances in supersonic regime.

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.

The study presents a numerical investigation of aerodynamic drag reduction by implementing a counterflow plasma jet, emanating from the stagnation point of an aerodynamic surface in a supersonic regime with a constant pressure ratio PR  = 3 , and compares findings with a conventional opposing jet. The computational study is carried out by solving three-dimensional and axisymmetric Navier–Stokes equations for counterflow plasma-jet interaction. The calculations are performed at free-stream Mach ( M ∞  = 1.4) with sea level stagnation conditions. The weakly ionized argon plasma jet generated by a plasma torch has constant stagnation pressure and temperature of 303,975  Pa and 3000  K . The effect of the Mach number and the angle of attack variation on plasma-jet effectiveness is also analyzed. The results indicate that the counterflow plasma jet reduces more drag (in twice) compared to the conventional jet (nonplasma). The gravitational, magnetic field effect and chemical processes in the plasma formation are considered negligible. It is inferred that the effectiveness of the counterflow plasma jet strongly depends upon the jet stagnation temperature.

No abstract