建立了一个基于Euler方程和自由尾迹分析的新的、高效的混合计算方法,用于旋翼桨-涡干扰(BVI)气动和噪声特性的研究。在该方法中,仅针对单片桨叶进行计算,通过求解Euler方程来捕捉流场中旋翼近尾迹的影响以及桨叶表面的非定常载荷,流场空间中旋翼远尾迹的位置由自由尾迹模型给出;提出了广义网格速度方法以将旋翼远尾迹的影响耦合到流场的求解中;噪声的分析采用基于声学类比法的FW-H方程。应用上述方法对AH-1/OLS旋翼BVI状态的气动载荷和噪声进行了计算,并与可得到的试验数据对比,验证了方法的有效性。计算结果表明:下降飞行状态的旋翼,在桨盘面会产生多处BVI现象,而干扰脉冲载荷主要来自桨叶前缘10％弦长内的压强突变;典型的BVI噪声具有多个正、负脉冲声压,且具有较强的方向性。

A new hybrid method based on Euler equation and free wake analysis is developed for studying the aerodynamic and acoustic characteristics of rotor blade-vortex interaction (BVI). In this method, the flowfield of just one blade is solved. An Euler solver is used to capture the effect of near wake and unsteady loading on the blade surface; a free wake model is employed to account for the effect of the far wake. To simplify computation, an effective approach called the generalized grid-velocity approach is presented. The acoustic prediction is based on the well-known FW-H equation. By this method, the aerodynamic loading and acoustic calculations are performed for an AH-1/OLS rotor in the BVI condition. A comparison with available experimental data has validated the present method. Also, the computation results indicate that, the BVI phenomena will occur at several azimuthal angles on the rotor in the descent flight condition, and that BVI loading is mainly caused by the high rate of change of pressure within 10% of the leading edge. The typical BVI noise is impulsive and has strong directivity.