基于目标压力分布的旋翼先进气动外形反设计分析方法

基于雷诺平均Navier-Stokes（RANS）方程、运动嵌套网格、目标压力分布及余量修正方法，构建了一套直升机旋翼桨叶先进气动外形反设计方法。为避免由桨叶气动外形变化导致的网格畸变，发展了一套基于Poisson方程求解的旋翼桨叶结构化贴体正交网格的快速、自动化生成方法，为提高运动嵌套网格的生成质量和通用性，采用剖面间网格插值与桨尖翻折相结合的方法，同时建立了基于“Top Map”和“Inverse Map”相结合的洞边界划定和贡献单元搜寻的新方法。基于Navier-Stokes方程和双时间法建立了旋翼非定常流场模拟方法，通量求解采用Roe-MUSCL格式，并使用低速预处理法来克服前飞旋翼流场收敛中遇到的刚性问题。在计算流体力学（CFD）方法基础上，基于旋翼翼型压力系数余量联立各方位角处的反设计MGM（Modified Garabedia-McFadden）超定方程组，并依据激波分离、失速等约束设置了各方位角处的反设计权重系数，创建了基于MGM超定方程组最小二乘解的旋翼气动外形（翼型）设计方法。应用所建立的方法，分别针对多目标、多状态和前飞时的旋翼（翼型）气动外形进行反设计分析，验证了本文方法的有效性。最后，将该方法拓展应用到旋翼桨尖气动外形设计中，设计得到与UH-60A直升机旋翼气动特性相似的矩形桨叶外形。

Inverse Design Analysis Method on Rotor with Advanced Aerodynamic Configuration Based upon Target Pressure Distribution

An inverse design method for a helicopter rotor with advanced aerodynamic configuration is established based on Reynolds-averaged Navier-Stokes (RANS) equations, moving-embedded grids, target pressure distributions and the iterative residual correction principle. In order to avoid the distortion of the grids around the blade due to configuration change, a fast and automated generation method of the body-fitted and orthogonal grids around the rotor blade is employed by solving the Poisson equations. To improve the quality and robustness of the moving-embedded grids, a strategy of grid generation is proposed by combining the interpolation of section grids and the folding of blade tip grids. Simultaneously, a new approach for determining the hole boundary and searching donor cells is created by the combination of "Top Map" and "Inverse Map" methods. The solution of the unsteady flowfield of the rotor is accomplished by employing the Navier-Stokes equations and a dual-time scheme. The convective flux is calculated by a Roe-MUSCL scheme, and a preconditioning approach is employed to overcome the stiffness of flowfield convergence. Based upon the computational fluid dynamics (CFD) numerical simulation, the MGM (Modified Garabedia-McFadden) inverse design overdetermined equations are established at different azimuthal angles based on the residual of pressure coefficients, and the weight factors at different azimuthal angles are set up according to the restriction of shock wave separation and dynamic stall. An inverse design method for the aerodynamic configuration (airfoil) of the rotor is developed by the least square solution of the overdetermined MGM equations. The inverse design analyses on multi-target, multi-state and rotor (airfoil) aerodynamic configurations in forward flight are performed respectively by using the present method, and the effectiveness of the method is identified. Finally, the inverse design method is used successfully to design a rectangular rotor with new airfoils which possesses aerodynamic characteristics similar to the UH-60A helicopter rotor with its new tip blade.