COMPUTATIONS OF AERODYNAMIC DRAG FOR SPINNING TRANSONIC PROJECTILES USING AN IMPLICIT TVD SCHEME

The performance of a spinning secant-ogive-cylinder-boattail projectil e in the transonic regime in terms of aerodynamic drag has been analyz ed numerically in this study. To obtain an accurate prediction of the spinning effect on individual drag components and total drag of a proj ectile for the shell design, the implicit, diagonalied, symmetric Tota l Variation Diminishing (TVD) scheme, accompanied by a suitable grid, is employed to solve the thin-layer axisymmetric Navier-Stokes equatio ns associated with the Baldwin-Lomax turbulence model. The computed re sults show that, in comparison with the non-spinning case, to increase the spin rate can result in increases in viscous drag and nose pressu re drag, but can cause decreases in boattail drag and base drag. The v ariations of these drag components result in only a small (less than 5 %) increase in total drag; thus the performance of the transonic proje ctiles is found to be insensitive to the spin rate.