乘波体压缩面变化对其气动性能影响分析

乘波体是一种利用激波包裹特性获得高升阻比的高速飞行器构型.已有研究中,乘波体气动性能的改善主要依赖于给定源流场条件下的前缘型线优化.本文采用数值优化和计算流体力学模拟为主要手段分析了乘波体压缩面变化对其气动性能的影响,以期有效拓展乘波体的设计空间.主要内容如下:首先给出了一种基于表面局部变形的乘波体设计方法.其次结合运用增量修正参数化方法、计算流体力学分析和微分演化算法构造了乘波体压缩面外形气动优化设计流程,以一种椭圆锥形流场生成的乘波体作为基准构型开展了无黏优化.之后从优化结果中选择升阻比递增的6个典型构型进行前缘钝化处理后,基于N-S方程对其气动性能进行了评估.最后综合依据无黏/黏性计算结果分析了乘波体压缩面变化对其气动性能的影响.结果表明该部分形状的改变对乘波体气动性能影响十分明显,在升力面积不变的条件下,乘波体压缩面形状变化可导致其升阻比出现成倍变化,即使在升力不减条件下,升阻比较基准构型也可获得超过14%的提升.此外,还可导致乘波体相对压心系数出现明显偏移.

EFFECT OF COMPRESSION SURFACE DEFORMATION ON AERODYNAMIC PERFORMANCES OF WAVERIDERS 1)

A waverider is a type of hypersonic lifting body that has the entire bow shock underneath the body as well as attached to the leading edge when flying at its design Mach number.Present research for improving the aerodynamic performance of waveriders mainly focused on searching an optimal profile of the leading edge on the condition of given a specific generating flow field.In order to further extend the design space of waveriders, a novel design method that is based on a local shape deformation technique is presented in this paper.Moreover, an inviscid analysis-based optimization study was carried out to research the effect of compression surface deformation on aerodynamic performances of waveriders by integrating the increment-based parameterization method, the computational fluid dynamic analysis, and the differential evolution algorithm.Afterwards, six selected waverider configurations were polished to blunt leading edges, and then their aerodynamic performances were evaluated by solving the Navier-Stokes equations.The results show that both the L/D and the relative pressure center coefficient of the waveriders produce significant changes with the variation of compression surface shape.Among all waveriders, the maximal difference of the L/D is more than double.Even by considering the lift constraint, the increment of the L/D is more than 14 percent in comparison with the baseline configuration.In addition, the value of relative migration of the relative pressure center coefficients is remarkable.