共轴刚性旋翼气动外形优化设计

采用前行桨叶概念(Advancing blade concept,ABC)的共轴刚性旋翼构型的直升机具有高速前飞的能力,然而大前飞速度带来的强桨尖压缩性等影响对桨叶气动外形提出了更高的要求。鉴于此,本文针对共轴刚性旋翼的气动布局进行了优化设计,通过改进桨叶平面外形提升旋翼前飞性能。基于雷诺平均NS(Reynold-saveraged Navier-Stokes,RANS)方程对共轴旋翼流场进行了气动性能数值模拟,在此基础上建立了代理模型结合遗传算法(Genetic algorithm,GA)的高效共轴旋翼气动布局优化方法,以前飞升阻比为目标函数进行优化,得到约束外形下的具有非线性弦长分布、尖削及后掠特征的桨叶外形。试验结果表明优化桨叶相比基准矩形桨叶升阻比得到明显的提升(前进比为0.6状态下升阻比提升约30%),证明了优化的有效性。

Optimization Design of Coaxial Rotor Aerodynamic Planform

Coaxial rigid rotor helicopter using advancing blade concept (ABC) is capable of high speed forward flight. However large area of reverse flow region and intense blade tip compressibility brought by high forward speed put forward higher requirements for blade planform. In light of this, optimization design of coaxial rotor planform is conducted to impove forward performance by changing blade planform. Coaxial rotor flow-field is simulated by solving Reynolds-averaged Navier-Stokes (RANS) equations. An optimization method combining surrogated model and genetic algorithm (GA) is established based on aerodynamic simulations. The optimized blade features nonlinear chord distribution and tapered sweptback blade tip under geometry constraints when lift-drag-ratio is set as objective function. Compared with baseline rectangular blade, the optimized blade has a higher lift-drag-ratio (When the advance ratio is 0.6, the lift-to-drag ratio is increased about 30%), which proves the optimization is valid.