超高层建筑气动噪声场的大涡模拟

Large Eddy Simulation of Aerodynamic Noise Field Around Super High-Rise Buildings

为揭示超高层建筑气动噪声产生的机理及空间分布特征,利用大涡模拟,在大气边界层内求解超高层建筑绕流场,结合FW-H(Ffowcs Williams-Hawkings)方程的声类比法进行了超高层建筑周围声压场的数值模拟.研究发现:超高层建筑每个面均是偶极子声源,气动噪声是由建筑表面的偶极子声源产生,且受建筑表面风压主导,顺流向和横风向的脉动压力分别主导相应方向的声场辐射强度;气动噪声沿高度方向先增大后减小,在0.7倍建筑高度附近噪声达到最大值;在相同高度和离建筑表面相同距离的不同空间点,当空间点面对建筑迎风面时总声压级最大、背风面次之,侧风面最小;随着空间点与建筑距离的增大,空间点总声压级快速衰减,且横风向较顺风向衰减更快.研究认为:大涡模拟和声类比相结合的方法能合理预测超高层建筑的气动噪声;优化气动外形,降低建筑表面风压是降噪的最有效途径.

In order to reveal the mechanism and spatial distribution characteristics of aerodynamic noise around super high-rise buildings,the flow field around super high-rise buildings in the atmospheric boundary layer is solved by using large eddy simulation(LES),and the sound pressure field is numerically calculated by the acoustic analogy method(Ffowcs Williams-Hawkings,FW-H).The result shows that each surface of super highrise buildings can be regarded as a source of dipolar noise.The aerodynamic noise is generated by a dipole source on building surfaces and is dominated by the wind pressure on those surfaces.The radiation intensity of the sound fields in the along-wind and cross-wind directions is controlled by the corresponding fluctuating pressures.Aerodynamic noise first increases and then decreases with the height,with the maximum value arriving at the approximately 70%of the building height.For spatial points with the same height and distance to building surfaces,the highest total sound pressure will occur at the points facing the building's windward surfaces,followed by that at the points facing the building's leeward surfaces.The lowest total sound pressure will appear at the spatial points facing the building's side surfaces.With the increase of the distance between spatial point and building,the total sound pressure level decreases rapidly.The total sound pressure level decreases more rapidly in the cross-wind direction than in the along-wind direction.This work suggests that the LES method combined with the acoustic analogy method is a feasible way to predict aerodynamic noise produced by super high-rise buildings.The most effective way to reduce the noise level is to reduce the wind pressure on building surfaces by optimizing its aerodynamic shape.