Aerodynamics Analysis of Grid Fins Inner Lattice Structure in Cruise Missile

Abstract

Grid fins are normally placed at the rear end of cruise missiles, rockets and other ballistic devices to control their trajectory especially at the final stage of flight. These fins provided fine control of the pitch, yaw and other lateral movements, allowing for higher stability and accuracy of the cruise missiles. This project investigates computationally the relation between grid fins inner lattice structures dimensionless parameters and the fins aerodynamics drag coefficient. The project gathered data from 12 different fins by varying the parameters of its internal lattice structure such as thickness, width and chord at various angles of attack (0°, 20° and 40°). The freestream was set at a constant speed of 150 m/s that gives Reynolds number > 1.7 x 106 . The results were experimentally compared by using a re-scaled model of a single fin in a sub-sonic wind tunnel, achieving a difference in results of not exceeding 6%. The results obtained that as the width-chord ratio increases, the aerodynamics drag coefficient increases for fixed thickness-width ratio. The results also demonstrated that as the angle of attack increases, the aerodynamics drag increases. The thickness-width ratio has the larger impact on the aerodynamics drag. The results can be used to improve the design of guided cruise missiles.