共轴刚性旋翼干扰下机体外形对流场影响的数值模拟

Numerical simulation of airframe shape influence on flow field under the interference of coaxial rigid rotors

针对共轴刚性旋翼干扰下直升机开展了机体外形对流场影响的数值模拟研究。首先,基于动量源模型和雷诺平均N-S方程的数值模拟方法,进行了孤立共轴旋翼下方诱导速度分布和ROBIN机身压强分布的验证计算。然后,对孤立机体以及有双旋翼干扰的原机体进行数值模拟,比较了有无旋翼干扰的机体流场。最后,分析了机头外形、垂尾方向、平尾及垂尾大小对流场的影响。结果表明:高速前飞状态下,有旋翼干扰的机体阻力小于孤立机体的阻力;旋翼下洗流场对机头压力分布几乎没有影响,但对尾翼附近流场有影响;机头采用适当曲率能够减小阻力,垂尾朝向处流场更紊乱;垂尾、平尾越大,其影响区域越大、阻力越大。

The numerical simulation of the influence of the airframe shape on the flow field was carried out for the helicopter with coaxial rigid rotor interference. Firstly, based on the momentum source model and the numerical simulation method of Reynolds averaged N-S equation, the induced velocity distribution below the isolated coaxial rotor and the pressure distribution of ROBIN fuselage were calculated and verified. Then, the numerical simulation was carried out on the isolated airframe and the airframe with the interference of twin-rotor, and the flow field of the airframe with and without rotor interference was compared. Finally, the effects of nose shape, vertical tail direction,horizontal tail and vertical tail size on the flow field were analyzed. The results show that the airframe resistance with rotor disturbance is less than that with isolated airframe under high-speed forward flight. The rotor downwash flow field has almost no effect on the nose pressure distribution, but has influence on the flow field near the empennage. The proper curvature of the nose can reduce the drag, and the flow field at the vertical tail direction is more disordered. The larger the vertical tail and horizontal tail are, the larger its influence area and drag are.