A Computational Analysis of Ground Effect Influence on a Transonic/Supersonic Projectile

Abstract

The ground effect (GE) experienced by transonic/supersonic projectiles flying close to solid surfaces has been the subject of a significant research program at the University of New South Wales over the past several years. The present study examines how a nearby ground surface influences the aerodynamic forces and moments acting on a transonic/supersonic projectile in the range of M=1.1–1.5. This is done by means of a numerical analysis and a number of wind-tunnel tests conducted for both qualitative and quantitative validation. Experimental data has previously revealed different phenomena that occur over a range of ground clearances with the observed behaviour changing as the Mach number is varied. Different shock reflection configurations have been shown to develop for particular combinations of ground clearance and Mach number. The potential of the ground plane to induce a suction force on the projectile was found to cease to exist once the projectile reaches or exceeds M=1.5. The GE was also found to have an appreciable influence on other important flow field features including the bow shock stand-off distance, Mach-stem height, wake distortion/deflection, and the pressure distribution along the projectiles surface.