Complex Interaction Between a Fin and a Transverse Jet at Mach 5

Abstract

The maneuverability of high-speed flight vehicles such as fighters or missiles determines their survivability in dogfighting or penetrating missile defense systems. A combined attitude control system using both aerodynamic control surfaces and reaction control thrusters has been applied to some of the latest military flight vehicles. This paper aims to shed some light on the interaction between a control surface and a downstream control jet, which has rarely been studied. A model consisting of a flat plate, a fin, and a transverse jet is tested using various experimental techniques at Mach 5 to investigate the complex interaction between the fin and the downstream jet. Schlieren and planar laser scattering are used to study the pattern of shock wave interactions and structures in the boundary layer, and pressure-sensitive paint is used to examine the pressure distribution on the flat plate. The results show that the state of the approaching boundary layer, the structure of the jet-induced bow shock, and the pressure distribution around the nozzle are sensitive to the position of the jet relative to the fin. The pressure around the nozzle exit is substantially increased in all three cases tested, and the highest peak pressure occurs when the jet is located after the fin-induced reattachment shock. However, by integrating the surface pressure, the highest side force on the flat plate is noticed to occur when the jet nozzle is located between the fin-induced separation shock and reattachment shock.