Aerodynamic Analysis Of Two-Dimensional Trajectory Correction Projectile With Rotating Fixed Rudders

Two-dimensional trajectory correction projectile is a precise attack projectile formed by replacing the conventional fuze of uncontrolled high-speed rotating projectile with the PGK(Precise Guidance Kit)containing a pair of co-directional rudders and a pair of differential rudders.In the progress of trajectory correction,the correction of flight distance and direction can be carried out when co-directional rudders deflects in different directions.Rotating projectiles often induce a special kind of motion,which is called coning motion.The aerodynamic characteristics of two-dimensional trajectory correction projectile under coning coupled motion are different from those under double-spin motion.Using aerodynamic parameters under coning coupled motion to solve trajectory equations can improve the accuracy of trajectory prediction.In this paper,the numerical methods of aerodynamic characteristics of projectiles and rockets in double-spin and coning coupled motions are introduced in detail,and the aerodynamic characteristics of AFF standard model are simulated numerically.The numerical simulation results are compared with the literature results to verify the reliability of the numerical calculation method in this paper.In this paper,the variation of aerodynamic characteristics of two-dimensional trajectory correction projectile with Mach number and angle of attack under double-spin motion is studied,and the difference of aerodynamic characteristics between counter-rotation and non-rotation of PGK is emphatically compared.The results show that the PGK can adjust the normal force coefficient of the whole projectile,and the adjustment range is about ±3%,so as to correct the range of the two-dimensional trajectory correction projectile.PGK can also produce magnus effect in the process of reverse rotation,and the direction of the magnus force of the PGK will turn with the change of Mach number.At subsonic speed,the lateral force of the PGK is negative,and the direction is opposite to the lateral force of the projectile body.At supersonic speed,the lateral force of the PGK is positive,and the direction is the same as that of the projectile body.The lateral force of two-dimensional trajectory correction projectile will be produced by magnus effect in flight process,but the lateral force can be reduced by PGK,so as to achieve the purpose of adjusting the flight direction of two-dimensional trajectory correction projectile.A numerical method for calculating the coupling motion which consists of double spin motion and coning motion is proposed.The MRF method is used to simulate the coning motion of the corrected projectile,the moving mesh is used to simulate the double-spin motion of the corrected projectile,and the aerodynamic and moment coefficients of the corrected projectile are calculated with the coordinate system transformation.The method is verified by the AFF standard model.Based on the numerical method proposed in this paper,the aerodynamic characteristics of two-dimensional trajectory correction projectile under coning motion are obtained by ANSYS FLUENT software.The results show that when the angle of attack is zero or negative in coning coupled motion,the normal force coefficient can be increased by the correction of the co-rudder of the PGK.When the yaw angle is large,the lateral force coefficient of the two-dimensional trajectory correction projectile can be reduced by the correction of the PGK.Magnus force is perpendicular to the plane of high and low angles of attack.When the projectile is only doublespinning,Magnus force is lateral force.When the two-dimensional trajectory correction projectile is in coning coupled motion,the direction of Magnus force will change with the coning angle,and a part of Magnus force will be normal force.