Transonic and Supersonic Overtaking of a Projectile Preceding a Shock Wave

In this paper, two-dimensional an daxisymmetric, time dependent transonic and supersonic flows over a projectile overtaking a moving shock wave are considered. The flow is simulated numerically by solving full time averaged Navier-Stokes equations. The equations are linearized by Newton approach. The Roe s flux splitting method, second order central difference scheme for the diffusion terms and the second order approximation for time derivatives are used. For the turbulence terms, the Baldwin-Lom ax and mixing length turbulence models are used. The present algorithm captures complicated features of flow in cluding moving shock waves, expansion waves, boundary layers and wakes and th eir interactions. The results show that as the projectile passes through the moving shock wave, it changes the flow field features and pressure distribution dramatically. The drag force decreases and even becom es negative while the projectile takes over the shock wave. The flow features and the aerodynamic forces in transonic flow changes much more than those in the supersonic flow as the projectile passes ihrouqh. the shock wave. The results show that when the shock wave pass es though the projectile, the flow fi eld structures and the aemdynamic forces change abruptly . The drag force reduces and the shock wave passes throug h the projectile. Such variations are more vociferous for transonic flows than the supersonic flows. For transonic flows, the drag force changes sign and accelerates the projectile. Such behavior is important when the stability and control of the projectile are studied. Also such changes in pressure around the projectile and in the wake region change the projectile trajectory.