高层建筑脉动风力频域特性的阻塞效应试验研究

Experimental investigation of blockage effects on frequency domain characteristics of fluctuating wind forces on tall buildings

基于标准高层建筑模型的测压试验,研究了两种均匀湍流风场中阻塞效应对高层建筑标准模型层脉动风力及基底脉动力矩的功率谱、相关性和相干性的影响。结果表明:当阻塞比不大于4.5%时,可以忽略阻塞效应对高层建筑脉动风力频域特性的影响;当阻塞比大于4.5%时,在均匀低湍流度风场中,层脉动阻力功率谱在2倍旋涡脱落频率处出现尖峰;随着阻塞比的增大,层脉动升力和扭矩功率谱的峰值和斯托罗哈数均呈增大趋势;基底脉动力矩功率谱随阻塞比的变化规律与相应的层脉动风力类似。在均匀高湍流风场中,湍流的增加削弱了阻塞效应对高层建筑脉动风力频域特性的影响。

A group of standard tall building models with six different blockage ratios have been tested in smooth and grid turbulent flows by measurements by the synchronous multi-pressure sensing system.The effects of blockage on frequency domain characteristics including power spectral density,correlation and coherence of the fluctuating wind forces and the effects of turbulence intensity on blockage are investigated.The results show that the blockage effects can be ignored if the blockage ratio is no more than 4.5%.However,if the blockage ratio is greater than 4.5%,special peaks appear at twice of the Strouhal number in power spectra of fluctuating drags in the smooth flow.The peak values of the power spectra of fluctuating lift and fluctuating torque and the corresponding Strouhal numbers increase with the increase of the blockage ratio.The blockage effects on frequency domain characteristics are similar between the fluctuating base moments and corresponding fluctuating local wind force.In the grid turbulent flow,the increasing turbulence weakens the blockage effects on frequency domain characteristics of fluctuating wind forces.