翼型跨声速气动特性的不确定性及全局灵敏度分析

针对马赫数和仰角的随机不确定性会导致气动性能波动的现象, 采用非嵌入式的混沌多项式方法对绕NACA0012 翼型跨声速随机气动特性进行不确定性及全局灵敏度分析. 具体分析了飞行状态的不确定性对气动载荷分布、流场及气动力系数的影响并通过全局灵敏度分析找出重要因素. 不确定性分析结果表明翼型上表面的激波以及激波后分离泡是造成气动性能剧烈波动的主要原因. 灵敏度分析结果表明在跨声速区域马赫数对激波处气动性能影响最大, 此外, 虽然马赫数和仰角相互耦合作用对气动力系数贡献比较小, 但对于激波位置处的流场, 这种互耦合作用不可忽略. 

UNCERTAINTY QUANTIFICATION AND GLOBAL SENSITIVITY ANALYSIS OF TRANSONIC AERODYNAMICS ABOUT AIRFOIL

Considering the randomness of Mach number and angle of attack, the non-intrusive polynomial chaos method is employed to analyze the uncertainty and the corresponding global sensitivity indexes of transonic aerodynamics for the NACA0012 airfoil. In the paper, the uncertainty analysis and global sensitivity analysis about the aerodynamic loads, flow field and the aerodynamic coefficients are presented. The results of uncertainty analysis show that the flow characteristics in the shock disturbance region and the boundary-layer separation region are sensitive to the input uncertainties. This is the main reason for the aerodynamic performance fluctuations caused by parameter uncertainties. From the results of global sensitivity analysis, the fluctuations of flow characteristics near the shock wave region are dominated by Mach number. Moreover, the coupling effect between Mach number and angle of attack is significant and cannot be ignored in shock disturbance region. However, this coupling effect is very weak from the results of aerodynamic coefficients.