基于二级声辐射模型的地面声场高效预测方法

建立了可用于直升机运动状态下噪声传播特性分析的高效地面声场预测方法。该方法包括计算旋翼气动、噪声的自由尾迹方法和时域FW-H方程；计入大气、地面等环境因素的声传播模型及地面声场计算模型；为提高计算效率，在声源计算与噪声传播之间引入基于“紧致球声源”的二级声辐射模型；在此基础上，还提出了通过建立“特征参数声辐射球库”以实现直升机运动状态下噪声实时预测的方法。以AH-1旋翼为算例，通过与地面声场直接计算法对比，说明了方法的有效性及高效性；此外，文中还分析了大气、地面等环境因素对噪声传播以及地面声场特性的影响。

Efficient ground noise prediction method based on secondary noise radiation model

An efficient ground noise prediction method for the analysis of helicopter noise in flight based on the secondary noise radiation is developed. The method to predict the aerodynamic force and aeroacoustic characteristics based on the free-wake/FW-H, the noise propagation model that can take the effects of atmosphere absorption, ground absorption and reflection on noise radiation characteristics into account, as well as ground noise computation model are included in this method. In order to improve computational efficiency, the secondary sound radiation model built on the hypothesis of compact source is introduced between the noise source computation and noise radiation. To achieve the real time simulation of ground noise, the noise radiation model database is built according to the idea of parametric modeling. The efficiency and effectiveness are illustrated through the comparison of computed results and compute time with the direct computing method for AH-1 rotor. Furthermore, the effects of atmosphere and ground on noise radiation as well as ground noise characteristics are analyzed with this method.