反流及径向流动相互作用下刚性旋翼气动特性研究

采用雷诺平均(Reynolds-averaged Navier-Stokes,RANS)方程针对直升机前飞不同前进比状态下四叶片刚性旋翼开展数值模拟研究,对比前进比0.1和0.6时的旋翼气动特性差异。计算结果表明,前飞时桨盘后行侧根部附近出现反流流动区域,翼型截面压强系数呈现非常规分布,该区域桨叶几乎不提供升力,且反流区面积随前进比的增大而增加。以静态前掠反流翼段为研究对象,采用脱体涡(Detached eddy simulation,DES)方法研究其非定常空气动力学特性,发现反流翼段表面出现特殊复杂的附着涡结构,在展向流动的影响下,翼段根部与尖部的涡结构发生耦合作用;反流翼段的升力系数随桨距角的增加而增大,且在失速迎角后并未下降。

Numerical Study of Sweep Effect on Aerodynamic Characteristics of Helicopter Rotor Blade in Reverse Flow

The aerodynamic characteristics of a rigid four-bladed rotor in forward flight at advance ratio of 0.1 and 0.6 are simulated numerically with Reynolds-averaged Navier-Stokes (RANS) methods and compared with each other. The computed results indicate that reverse flow occurs near the root area of the retreating side of the rotor, giving rise to the unconventional distributions of pressure coefficient. And the proportion of the reverse flow region, where hardly any lift is contributed, is directly related to the advance ratio and increases with the raise of the advance ratio. Detached eddy simulation (DES) method is used to calculate the unsteady aerodynamic characteristics of a yawed flat blade in reverse flow. It is found that complex attached vortex structure occurs on the surface of the blade and the vortex near the root interacts with that near the tip area under the effect of the radial flow. The lift coefficient is directly proportional to the pitch angle and does not drop after the stall angle of attack.