Lateral Reaction Jet Flow Interaction Effects on a Generic Fin-Stabilized Munition in Supersonic Crossflows

Abstract

Abstract : The flow interaction effects from a jet issuing into a supersonic crossflow were investigated computationally for the case of a flat plate and a generic fin-stabilized projectile. For both configurations, simulations were performed at several Mach numbers and jet total to freestream static pressure ratios (PRs). In the flat plate case, the jet force was generally amplified, with a strong dependence on PR and the freestream Mach number. In the projectile configuration, seven jet locations along the missile axis were investigated at three supersonic crossflow Mach numbers and five angles of attack in the range 10 deg /= a /= 10 deg. The jet force was generally attenuated, unless the jet was located very close to the tail fins. In the latter case, this results from (1) a combination of little or no projectile surface area for the detrimental jet interaction effects to act on, and (2) the high pressures developed on the fin surfaces. The choice of turbulence model was found to affect the local pressure distribution due to the flow interaction, but the jet interaction force parameters varied less than 15% and 6% for the flat plate and missile configurations, respectively. The effect of angle of attack on jet interaction forces was more prevalent as a became more negative and the counter-rotating vortex pair in the jet plume was pushed closer to the tail fins. Flight simulations using reaction jet squibs were performed to evaluate the sensitivity of the control maneuver to the differences in jet thrust and jet actuation location. These results showed that significant differences in the projectile maneuver control were obtained if the effective jet thrust acting at the effective jet location were used instead of the ideal jet thrust acting at the jet exit location.