Study of Coefficient of Drag and Shock wave pattern for 155mm ERFB (BT) Supersonic Artillery Shell with Recovery Plug / Fuze

Abstract

In the present study, the drag variation and trajectory elements estimation of a supersonic projectile having two different nose shapes are made numerically and experimentally. The study aims at finding the coefficient of drag and shock wave pattern for 155 mm ERFB (BT) artillery shell fitted with recovery plug or with fuze, when travelling at zero angle of attack in a supersonic flow of air. The coefficient of drag (CD0) obtained from the simulation is used as an input parameter for estimation of trajectory elements and preparation of Firing Tables. The numerical results, i.e., the coefficient of drag at different Mach numbers and trajectory elements are validated with the data recorded by tracking radar from an experimental firing. Based on numerical results and data recorded in experimental firing, the coefficient of drag in the case of the shell with recovery plug is compared with shell with fuze. The shockwave in the case of the shell with recovery plug is detached bow shock wave, whereas in the case of a shell with fuze, the shock is attached. The results indicate that the coefficient of drag increases with detached shock wave and an increase in the radius of the shell nose. Good agreements are observed between numerical results and experimental observations. The Firing Table prepared from the study is used in dynamic test and evaluation of armament stores.