二次曲线截面弹身的气动设计及优化

非圆截面弹身外形飞行器是当前飞行器设计的一个重要发展方向。利用平面斜切圆锥获得的二次曲线可以构造圆、椭圆、抛物线及双曲线等典型的飞行器截面形状。采用模线设计方法并引入二次曲线形状控制参数，可以快速简便且精确地构造各种二次曲线弹身形状。发展了一套可以预估横截面为二次曲线的飞行器高超声速纵横向气动力工程计算方法。提出并建立了二次曲线截面弹身飞行器的优化设计模型，并利用相同的优化模型对圆截面、椭圆截面、双曲线截面及抛物线截面外形进行了优化。最后，对二次曲线截面弹身外形飞行器的气动特性进行了比较。

Aerodynamic Design and Optimization for Vehicles with Conic Cross Section

One of the most important development tendencies for current and future hypersonic vehicle is to design the vehicle with an asymmetric cross section configuration. Vehicle with asymmetric cross-section has a better rigidity, bigger volume, higher trimming lift and trimming lift-to-drag ratio which benefits the increasing of landing precision, enlargement of the flight corridor, decreasing of the peak heat flux and the over load. Furthermore, it is of practical importance for the stealth performance. The typical cross sections, such as circle, ellipse, parabola and hyperbola, can be generated by a slanted cut through a right circular cone, and the shape of the conic form depends upon the angle of the cut through the cone. Using Spline Lofting design process, together with the introduction of conic shape parameter, the various conic cross sections can be constructed rapidly, conveniently, accurately and respectively according to the various requirements of a vehicle designer. An engineering model is developed to estimate the longitudinal and the transverse aerodynamic characteristics of conic cross section vehicle, the correctness and effectiveness of this method are validated by the comparison with Space Shuttle database ADDB, and the results shown that the accuracy of the presented method is sufficient for the conceptual design. A multiple objectives optimization method is presented and a configuration optimization model for vehicle with conic cross section is defined to maximum the lift-to-drag ratio and the lift, together with the optimizations for vehicles with circular, elliptical, parabolic and hyperbolic cross section under the constraints of equal length and base area. Finally, the aerodynamic efficiency of different vehicles are compared and analyzed. The optimum results shown that the key issue for higher lift-to-drag ratio is the design of windward surface, and the leeward surface is more important for the inner volume and enclosed structure. The present work indicates the Spline Lofting method coupling with configuration optimization is an effective way for the design of a vehicle with conic cross section, and the asymmetric cross section geometries are one of the feasible choices for hypersonic maneuver, and need to be investigated further in the future.