Aerodynamic Analysis of Grid-Fin Configurations at Supersonic Speeds

Abstract

An aerodynamic prediction method for the estimation of aerodynamic characteristics of grid-fin configurations at supersonic Mach numbers has been developed. The method is based on shock-expansion theory. The shock and expansion relations and the interactions between the shock and expansion waves are used to predict the pressure distribution inside each grid-fin cell. The effect of body is modeled using doublet in the crossflow plane. The effect of symmetric separated vortices from the leeward side of body is also modeled using empirical data for the strength and location of vortices. The present method has been validated with available experimental data for body grid-fin configurations at angles of attack without and with fin deflection. The comparison of normal force coefficient on the individual grid fins as well as the overall normal force, pitching moment, and axial force coefficient with experimental data is good. Effect of roll orientation on normal force, pitching moment, and induced out-of-plane force is also brought out.