Simulation of Missiles with Grid Fins Using an Actuator Disk

Abstract

An actuator disk for grid fin simulations has been integrated in the DLR, German Aerospace Center’s TAU unstructured code. With this method, the physical grid fins are replaced by artificial boundary conditions in the flow for the numerical simulations. The objective in using an actuator disk is to reduce the computational effort during the design loops of vehicles equipped with grid fins. The forces produced by the grid fins are computed using a procedure based on the semiempirical theory for lattice wings and coupled with the code. The final tool is applied to the predictions of force and moment coefficients around a missile with grid fins. The numerical predictions are compared with the experimental data obtained at DLR for aMach number range from 1.8 to 4 and different angles of attack. In addition, computations for a body alone have been performed to be used as a reference to assess the code capabilities in recovering the experimental differences of force and moment coefficients between the complete missile and the body alone. The results for several Mach numbers show the capability of the method to predict the differences found experimentally between the drag of the vehicle and the body. The numerical simulations with angle of attack show good agreement with the experiments for force coefficients and pitching moment. The capabilities of the tool at different Mach numbers and angles of attack and its usefulness for the design of vehicles equipped with grid fins are shown.