Aeroacoustic Noise Characteristics of Flow around a Square Column Based on Large Eddy Simulation

基于大涡模拟的方柱绕流噪声特性研究

School of Marine Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China

Received: 15 August 2019

Abstract

Large eddy simulation and Ffowcs Williams-Hawkings (FW-H) equation were used to investigate the aeroacoustic noise characteristics of flow around a square column. After verifying the accuracy of the numerical model, the influences of flow velocity and flow direction on noise field characteristics are discussed. The noise prediction result of the base model was in good agreement with the experiment data in the vortex-shedding frequency and in the general trend. It was shown that there were typical dipole noise sources in the direction of 110° and 250°, respectively. With the increase of distance, the total sound pressure level was decreased and the directionality of the noise field is becoming worse. The results showed that the vortex-shedding frequency was increased with the increase of flow velocity, and the corresponding sound pressure level was also raised. The change of flow direction would make the directionality of noise flied more complicated, which is related to the complexity of flow field.

摘要

采用大涡模拟结合Ffowcs Williams-Hawkings(FW-H)方程声类比的方法，研究了方柱绕流噪声特性，将基准模型数值计算结果与前人试验结果进行对比，并分析方柱绕流噪声辐射特性以及流速和流向对声场的影响规律。研究表明：基准模型数值计算结果与试验值较为一致，说明了文中计算方法的适用性；在约110°和250°的圆周方向上的存在偶极子噪声模态，且随着距离的增大，噪声辐射声压级逐渐减小，噪声指向性变得逐渐不明显；随着流速的增大，涡脱落频率逐渐增大，且涡脱落频率处的声压级也随之增大，辐射噪声声压级在频域上呈增大趋势；流向的改变使得方柱绕流辐射噪声的声场指向性变得复杂。