Computational fluid dynamics analysis of a missile with grid fins

An approach for using viscous computational fluid dynamic simulations to ca lculate the flowfield and aerodynamic coefficients for a missile with grid fins is presented. A grid fin is an unconventional lifting and control surf ace that consists of an outer frame supporting an inner grid of intersectin g planar surfaces of small chord. The calculations were made at a Mach numb er of 2.5 and several angles of attack for a missile without fins, with pla nar fins, and with grid fins. Comparing the computed aerodynamic coefficien ts for the missile and individual grid fins against wind-tunnel measurement data validated the results. Very good agreement with the measured data was observed for all configurations investigated. For the grid fin case, the a erodynamic coefficients were within 6.5% of the wind-tunnel data. The norma l force coefficient on the individual grid fins was within 11% of the test data. The nonlinear behavior of the normal force on the leeward fin at high er angles of attack was also accurately predicted.