Simulation-Based Optimization Design For Fins Of A Missile With Wrap-Around Fins

Wrap-Around Fins (WAF) have been widely used in many kinds of tactical weapons since the middle of 1950's when they were come into use. They can be used in child-mother bomb because of characteristics of shape which can wrap around with surface of body of missile to reduce the diameter of mother bomb. Curvature of wing of missile brings strong roll moment as well.The thesis makes use of method of regression orthogonal design to select eight initial shapes in the space of design. Aerodynamic characteristics of every shape are computed by numerical simulation. The table of force coefficient and moment coefficient is gained while Mach number is at 0.01, 0.05, 0.1, 0.2, 0.3, 0.6 and 0.9, spin rate rotating by negative axis of missile is at 0, 1250, 2500, 3750 and 5000 r/min, attach angle is at 0, 20 and 40 degrees, yaw angle is at 0 and 10 degrees. Six-degrees-of- freedom (6DOF) motion equations of missile in trajectory and launch coordinate system are constructed by Euler method and Quaternion method with the Euler angles defined by the method of 231 or 321, force coefficient and moment coefficient are interpolated so as to be used into trajectory simulation. The trajectory parameters of initial shapes are computed then. The model of response surface of the end height and the end velocity is gained by regression analysis, and the problem is translated to a restriction nonlinear optimization problem. The optimization solution is gained by sequential quadratic programming (SQP). Six-degrees-of-freedom (6DOF) motion equations of missile in wind field in trajectory coordinate system are constructed by Euler method with the Euler angles defined by the method of 231, and the trajectory is simulated at the model of wind field of the constant wind, shear wind, atmospheric turbulence and discrete gust. Furthermore, the pane model of 6DOF trajectory is established by means of Aerospace Blockset of MATLAB/Simulink and simulated. The distributing of points of fall are evaluated by Monte Carlo method (MCM), the result that probability of hit the target of points of fall is 55.8% is computed, which can meet the needs of requirement.