基于大涡模拟的CAARC模型角区开槽气动优化研究

Aerodynamic optimization of corner slotting in CAARC model based on LES

超高层建筑属风敏感结构,对建筑外形进行适当气动优化可有效降低结构风荷载及风致响应。基于大涡模拟(LES)方法,采用一种新的入口湍流生成方法——NSRFG(narrow-band synthesis random flow generation)方法,进行超高层建筑标准模型(CAARC)角区开槽的气动优化研究。首先进行了CAARC高层建筑标准模型绕流模拟,并将模拟结果与风洞试验结果对比,以验证NSRFG方法的适用性;然后以CAARC模型为基础,设计了4种开槽气动优化方案,通过LES模拟得到基底弯矩功率谱,以估算建筑顶部位移响应和顶部峰值加速度响应。结果对比显示:对于矩形截面高层建筑标模,无论原型还是4种开槽气动优化方案,横风向脉动响应和峰值加速度响应整体比顺风向大;与全封闭原型相比,采取不同开槽方案均能降低顺风向和横风向风振响应,其中角区开槽对顺风向响应的优化效果最好,周向开槽对横风向响应的优化效果最好;4种开槽方案对于横风向响应的优化效果明显优于顺风向,其中相对而言周向开槽优化效果相对最好,使横风向脉动位移响应和横风向峰值加速度响应分别降低28.4%、32.8%。因此,从减小矩形截面超高层建筑结构横风向响应角度考虑,建议采用周向开槽方案。

Super high-rise buildings are wind-sensitive structures,and appropriate aerodynamic optimization of building shape can effectively reduce structural wind load and wind-induced responses.Here,based on large eddy simulation(LES)method,adopting a new inlet turbulence generation method proposed called narrow-band synthesis random flow generation(NSRFG)method,aerodynamic optimization of corner slotting in CAARC standard model for super tall buildings was studied.Firstly,flow simulation of CAARC standard model for high-rise buildings was performed,and the simulation results were compared with wind tunnel test results to verify the applicability of NSRFG method.Then,based on CAARC model,4 slotting aerodynamic optimization schemes were designed,and the base bending moment power spectrum was obtained with LES to estimate displacement response and peak acceleration response of building top.The comparison of results showed that for rectangular cross-section high-rise building standard model,regardless of the prototype or 4 slotting aerodynamic optimization schemes,pulsation response in transverse wind direction and peak acceleration response are generally larger than those in windward direction;compared with the fully enclosed prototype,adopting different slotting schemes can reduce wind-induced vibration responses in both windward and crosswind directions,in which corner slotting scheme has the best optimization effect on windward response and circumferential slotting scheme has the best optimization effect on crosswind response;the optimization effect of 4 slotting schemes on crosswind response is obviously better than that in downwind direction,in which circumferential slotting optimization effect is relatively the best to reduce crosswind pulsation displacement response and crosswind peak acceleration response by 28.4%and 32.8%,respectively;therefore,from the perspective of reducing crosswind response of rectangular cross-section super high-rise building structures,to adopt circumferential slotting scheme is suggested.