基于半模型的高速列车远场气动噪声计算方法

随着高速列车运行速度的提高，其气动噪声问题逐渐凸显，如何准确快速预测高速列车的远场气动噪声成为关键.利用半自由空间的Green函数求解FW-H方程，推导了考虑半模型时的远场声学积分公式，提出通过半模型的数值计算结果预测全模型高速列车远场气动噪声的方法；建立了全模型和半模型高速列车的气动噪声数值计算模型，应用改进延迟的分离涡模拟方法对不同模型高速列车表面的气动噪声源进行求解；通过风洞试验进行了全模型高速列车的数值仿真计算方法验证；对比分析了全模型和半模型高速列车周围的流场结构、气动噪声源和远场气动噪声特性.结果表明：半模型高速列车数值计算得到的列车周围流场结构、气动噪声源以及远场气动噪声特性与全模型的一致；采用半模型计算会过高估计列车尾车流线型区域表面压力的波动程度和噪声源的辐射强度，但通过半模型预测整车模型的远场噪声平均声压级误差小于1 dBA；相比于全模型高速列车，半模型计算时的网格总量减少一半.

Numerical Approach for Far-Field Aerodynamic Noise of High-Speed Trains Based on Half Model

With the increasing running speeds of high-speed trains, the problem of aerodynamic noise is gradually becoming more prominent. Determination of a method to predict the far-field aerodynamic noise of high-speed trains accurately and quickly has therefore become an important aim. The far-field acoustic integral formula for a half-model train is obtained in this work by solving the Ffowcs Williams and Hawkings （FW-H） equation using the Green’s function for semi-free space. A method is proposed to predict the far-field aerodynamic noise of a full-model high-speed train using the numerical calculation results for the half-model high-speed train’s aerodynamic noise. Numerical calculation models for the aerodynamic noise characteristics of high-speed trains are established with both the full model and the half model, and the aerodynamic noise sources on the surfaces of high-speed trains for the different models are solved using an improved delayed detached eddy simulation method. The numerical simulation calculation method used for the full-model high-speed train is verified using wind tunnel tests. The flow field, aerodynamic noise source, and far-field aerodynamic noise characteristics of the full-model and half-model high-speed trains are compared and analyzed. The results show that the flow field, aerodynamic noise source, and far-field aerodynamic noise characteristics obtained from the numerical calculations of the half-model high-speed train are consistent with those of the full model. Using the half-model calculations, the degree of fluctuation of the surface pressure in the streamlined area of the tail car and the noise source radiation intensity will both be overestimated. The far-field noise average sound pressure level error of the full model predicted using the half model is less than 1 dBA. When compared with the full-model high-speed train, the number of grid calculations performed for the half model is halved.