Investigations Of Grid Fins Aerodynamic Shape Design And The Roll Characteristics Of Wing-body Configuration

The aerodynamic characteristics of grid fin at supersonic speeds should be investigated since it was already used on some conventional weapons like small diameter bomb by the U.S. Army. Aerodynamic shape of grid fin was designed in order to solve the drag problem, its aerodynamic characteristics were investigated by the method of numerical simulation and wind tunnel test, the roll damping characteristics of wing-body configuration with grid fin tails were studied by numerical simulation, and the rolling control characteristics of wing-body configuration with grid fin tails at different speeds and attack angles were also researched with wind tunnel test.The aerodynamic shape design of gird fin was studied, first the effects of chord-to-width ratio and fins with curvature brought to aerodynamic characteristics of grid fins were investigated by the method of wind tunnel test, especially the lift and drag characteristics. Computational model for investigating grid fin's aerodynamic characteristics at supersonic speeds was established, the flow characteristics of fins with curvature was analyzed by numerical simulation. Different method of leading edges swept and different swept angle of grid fins were investigated by the method of numerical simulation, the aerodynamic characteristics of these novel grid fins with the Mach number and angle of attack variation were investigated, and the lift-to-drag ratio increase effect were comparative analyzed. Numerical simulation results showed that leading edges swept grid fin could reduce the wave drag obviously, improve flow chocking phenomenon. The aerodynamic shape design could be a novel design to increase the lift-to-drag ratio of gird fins at supersonic speeds.Then the computational model was based on wind tunnel model of DRDC&ISL, structured mesh technology was applied in modeling mesh of complex geometry shape like wing-body configuration with gird fin tails. The steady-state computational fluid dynamic calculations was used to simulate wing-body configuration with grid fin tails roll by rotating the reference frame around the x-axis at the specified spin rate. The roll damping characteristics of wing-body configuration with grid fin tails at supersonic speeds was studied, including the roll damping derivative with the Mach number and angle of attack variation. Analysis about the variation of roll damping derivative was carried out by the way of flow distribution, in order to find the different aerodynamic characteristics comparing with planar fins. Compared with wing-body configuration with planar fins, roll damping derivative of wing-body configuration with grid fins had complex variation, which was due to the influence of flow chocking phenomenon, this derivative decreased as angles of attack increased, and the separated flow of wing-body configuration influences the leeward gridfin largely.Two different models were designed for canard-controlled configuration including planar fins and grid fins, researched on the influence of canard-controlled configuration aerodynamic characteristics especially the rolling characteristics of different tails at different speeds and attack angles with wind tunnel test, the effect of grid fins on reducing adverse induced rolling moment were studied, in order to improve the efficiency of canard-controlled configuration roll control. Wind tunnel test indicated the anti-moment's direction of canard-controlled configuration with grid fins was fixed, which made it possible to employ this characteristics to do adverse roll control at transonic speeds.