【摘要】 将三阶迎风格式(MUSCL)与通量差分裂方法相结合,以改进二阶中心差分格式导致较大尾迹数值耗散的不足,建立了基于N-S方程和嵌套网格技术的旋翼流场求解方法,提高了CFD/Kirchhoff方法中流场信息计算的准确性.在流场求解的基础上,提出了一种谐波展开分析方法,基于该方法,Kirchhoff公式中的被积函数可解析表达,从而简化了获得Kirchhoff公式中被积函数的插值方法,提高了插值效率和精度.用上述方法对旋翼跨音速流场的高速脉冲(HSI)噪声进行了预测,计算结果与实验数据一致;同时对高速脉冲噪声在不同桨尖马赫数时和不同方向观测点上的特点进行了计算和分析.结果表明:旋翼高速脉冲噪声具有很强的指向性,在桨盘平面内噪声最大,在桨盘下方,随着与桨盘平面的夹角增加,噪声的脉冲迅速减弱.更多还原

【Abstract】 To improve the accuracy in the simulation of rotor flowfield and noise in the CFD/Kirchhoff method,a combination of the third-order upwind scheme(MUSCL) and flux-difference splitting scheme,instead of the second-order center-difference scheme which may cause larger wake dissipation,is employed and a N-S solver based upon embedded grids is developed.On the basis of the flowfield solution,a harmonic expansion approach is presented for rotor far-field noise.The approach gives an analytical expression of the integral function in the Kirchhoff formula and thus improves the interpolation efficiency and accuracy.A rotor high-speed impulsive(HSI) noise is calculated and a comparison with available experimental data is made,and good agreement was demonstrated.In addition,the HSI noise of helicopter rotors at different tip Mach numbers and on different observer locations is calculated and analyzed.The calculated results indicate a highly directional nature of the rotor high-speed impulsive noise with a maximum in the plane of rotor,and the impulsive feature of the high-speed noise radiation weakened rapidly with the increase of the directivity angle below the rotor plane.更多还原