Numerical simulation of heating over the rudder shaft gap in hypersonic flow

Aerodynamic heating distributions were measured in vicinity of rudder shaft and inside the gap between the rudder and body of Ballistic Missile. Time-accurate predictions were performed using a hybrid Reynolds-averaged Navier-Stokes/ Baldwin-Lomax turbulence model. Gap size is varied and the extent of separation in front of the gap is a function of gap size. The structure of flow field and the heat flux distribution are given. The results indicate that when the height of shaft gap is lower than the thickness of the boundary layer nearby the shaft gap, the boundary layer is separated in front of the gap entrance, and then reattachment region is formed at the entrance of gap; the separation region is a region of high heat flux. The magnitude of peak heat flux nearby the gap is governed by the height of axle and Mach number. Region of peak heating is the stagnation of warhead when height of axle is higher than the thickness of the boundary layer. The region of peak temperature is at the warhead of bullet, the front edge of rudder experiences lower temperature, and the shaft gap experiences the lowest temperature of the three parts. The region of partial peak temperature near the gap changes from the lip of gap to the front edge of rudder shaft when the gap size is increased.