声屏障几何形状对高速列车气动噪声影响的数值模拟及降噪研究

基于Lighthill声类比理论分别求解高速列车气动噪声的产生和传播过程,首先由RNG k-ε湍流模型求得流场的稳态计算结果,之后采用大涡模拟和FW-H方程对比直立与半圆形声屏障降噪性能的差异,通过建立包含3节车编组的CRH380A型高速列车和2种声屏障在内的仿真模型,研究声屏障几何形状的改变对声学性能及降噪能力产生的影响。结果表明:圆心角为180°的半圆形声屏障在测点处的平均插入损失较大,同时对气动噪声的降噪需求有着良好的匹配,综合声学性能较传统的直立声屏障更优;缩小圆心角会导致半圆形声屏障的降噪能力相应降低,其插入损失在圆心角由180°减至120°的过程中呈现明显的下降趋势,之后的降幅相对较小,圆心角为30°的半圆形声屏障降噪效果已与等高的直立声屏障类似。

Numerical Simulation on Aerodynamic Noise and Reduction Effect of Sound Barriers with Different Geometric Shapes for High-Speed Train

Based on the Lighthill acoustic analogy theory, the generation and propagation of the aerodynamic noise of high-speed train were solved respectively. Firstly, the steady-state calculation results of the flow field were obtained from RNG k-ε turbulence model. Then the large eddy simulation and FW-H equation were adopted to compare the noise reduction performance of upright and semi-circular sound barriers. Based on the simulation model including CRH380A high-speed train with three-car formation and two kinds of sound barriers, the influence of sound barrier geometry on the acoustic performance and noise reduction capability of sound barriers was clarified. Results show that the semi-circular sound barrier with the central angle of 180° has larger average insertion loss at measuring points and a good matching for the reduction requirements of aerodynamic noise, and the comprehensive acoustic performance is better than the traditional upright sound barrier. Reducing the central angle will result in the corresponding reduction in the noise reduction ability of the semi-circular sound barrier, and its insertion loss will show a significant downward trend in the reduction process of the central angle from 180° to 120°, while the subsequent decrease is relatively small. Nevertheless, the noise reduction effect of the semi-circular sound barrier with the central angle of 30° is similar to that of an upright sound barrier of the same height.