Simulation of Store Separation from a Rectangular Cavity at Supersonic Speeds Using the Grid Method

Wind tunnel data of time-averaged aerodynamic forces and moments are used to simulate the trajectory of a store separating from a rectangular cavity at supersonic speeds. The aerodynamic database serving as the primary input for the simulations was developed over a series of test entries in the PolysonicWind Tunnel (PSWT) using a Captive Trajectory System (CTS) operated in grid mode. The wind tunnel data were obtained at Mach 2 and 4 for a generic store with a slenderness ratio of 8 and a cavity with a length-to-depth ratio of 4.5. Methods for interpolation and extrapolation of the experimental data used to expand the database are presented. A fourth-order Runge-Kutta scheme is utilized to numerically integrate the six-degrees-of-freedom (6DOF) equations of motion for an axisymmetric projectile. Store separation trajectories consisting of the translational positions (x,y,z) and angular positions (phi,theta,psi) are shown for several cases which demonstrate the effects of ejection velocity, initial pitch angle and pitch rate, and freestream Mach number.