Abstract

The noise of the main rotor of a helicopter in hover and horizontal flight modes is numerically simulated. To calculate the acoustic characteristics caused by the nonstationary load on the blades, a software package is used, validated with experimental data in hover mode. A hybrid calculation method is used, according to which the near field is calculated first, followed by the acoustic characteristics in the far field. In the near field, the values of the field parameters near the rotating blade are found by direct solution of the unsteady Euler equations in a noninertial coordinate system. To calculate the far field, the integral Ffowcs Williams–Hawkings method is applied using permeable control surfaces enclosing the blade.

中文翻译：

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飞行和悬停模式下直升机主旋翼的噪声指向性模式比较

摘要

数值模拟了悬停和水平飞行模式下直升机主旋翼的噪声。为了计算由刀片上的非平稳负载引起的声学特性，使用了一个软件包，该软件包已通过悬停模式下的实验数据进行了验证。使用一种混合计算方法，首先要计算近场，然后再计算远场的声学特性。在近场中，旋转叶片附近的场参数值是通过非惯性坐标系中非定常欧拉方程的直接解找到的。为了计算远场，积分Ffowcs Williams-Hawkings方法通过使用封闭叶片的可渗透控制面来应用。