基于非结构网格空间推进的高超声速飞行器背脊线优化

针对高超声速飞行器背脊线优化进行了研究。结合自由曲面变形(FFD)方法和Hicks-Henne型函数建立背脊线参数化模型,保证了飞行器背部曲面光滑连续。为减少计算耗时,采用非结构网格空间推进方法求解高超声速无黏流场,通过钝锥算例对该方法计算效率和精度进行了参数分析,并对飞行器流场计算进行了验证,对比表明表明:非结构网格空间推进算法计算效率提高4.5倍以上,计算结果与常规时间迭代法符合较好。采用优化拉丁超立方抽样建立响应面模型,分析了各设计变量对目标函数的影响。采用非支配排序NSGA-Ⅱ(non-dominated sorting genetic algorithm-Ⅱ)算法以阻力系数和升阻比为目标对背脊线优化,约束飞行器体积变化不超过20%。结果表明,飞行器阻力系数和升阻比呈负相关,优化后阻力系数降低7.1%,升阻比提高16.9%。 

Unstructured grid space marching based design optimization of hypersonic vehicle back sketch lines

The design optimization of hypersonic vehicle back sketch lines was investigated. A parametric geometry model was presented based on free form deform (FFD) method and Hicks-Henne function, which was capable of keeping the back surface smooth and continuous during deforming. In order to save time cost, unstructured grid space marching method was adopted to solve the Euler equations. The accuracy and efficiency of this method were analyzed by DOE methods through hypersonic cone cases. There was a good conformity between the un-structured grid space marching and time marching results of the hypersonic vehicle flow. Indicated by the comparisons, the unstructured grid space marching method had the capacity to increase the computational efficiency over 4.5 times. A response surface model was built through optimize latin hypercube sampling. The Pareto effects of design variables were analyzed. The multi-objective optimization algorithm NSGA-Ⅱ (non-dominated sorting genetic algorithm-Ⅱ) was adopted to optimize the drag coefficient and lift-to-drag ratio under the constraint of the vehicle volume change within 20%. The optimization history showed a negative correlation between the drag coefficient and lift-to-drag ratio. The drag coefficient of the optimal configuration decreased by 7.1% and the lift-to-drag ratio increased by 16.9%.