基于CFD方法的直升机旋翼/尾桨非定常气动干扰计算

采用CFD方法针对直升机旋翼/尾桨气动干扰问题进行了数值计算研究.建立了一个适用于旋翼/尾桨干扰气动力计算的方法.在该方法中,控制方程采用三维非定常雷诺平均Navier-Stokes(RANS)方程,网格系统使用嵌套网格技术以计及旋翼和尾桨的相对运动.基于所建立的方法,分别计算研究了悬停状态、低速前飞状态以及巡航平飞状态时干扰状态的旋翼和尾桨气动力,并深入分析了尾桨旋转方向对干扰特性的影响.计算结果表明:旋翼对尾桨的气动干扰在各计算状态都存在,且干扰影响不总是负面的,这取决于飞行状态;而尾桨对旋翼的干扰作用则在悬停状态时较为明显,但在前飞状态时可忽略不计;尾桨旋转方向对尾桨气动力的影响较大,合理地选择尾桨的旋转方向可以改善其气动特性.

Calculations of unsteady aerodynamic interaction between main-rotor and tail-rotor of helicopters based on CFD method

Numerical calculation research was performed for helicopter main-rotor/tail-rotor interaction by using the CFD method. A computational method was established for aerodynamic interactions of main-rotor/tail-rotor configuration, wherein the three-dimensional unsteady Reynolds-averaged Navier-Stokes (RANS) equations were used as the control equations, and overset grid technique was employed to simulate the relative motion between the main-rotor and tail-rotor. Based on the developed method, the aerodynamic characteristics of main-rotor/tail rotor interaction in hover, low-speed forward flight and cruising state were calculated, and the influence of the tail-rotor rotation direction on the interaction characteristics was analyzed. The results indicate that the interference influence of main-rotor on tail-rotor is obvious in all calculation states, but not always negative, depending on the flight condition. The interference influence of tail-rotor on main-rotor is relatively obvious in hover, but negligible in forward flight condition. In addition, the tail-rotor rotation direction has a significant effect on the aerodynamic force of tail-rotor, so reasonable selection of the tail-rotor rotation direction can improve the aerodynamics of tail-rotor.