不同风场中特高压换流站阀厅屋盖风压特性试验研究

Experimental study on the wind pressure characteristics of a UHV converter station roof in different wind fields

特高压(ultra high voltage,UHV)换流站阀厅的金属屋面系统在风荷载作用下易发生屋面表层风揭事故。为深入探讨该类建筑屋面的风压极值特性,基于风洞试验分别探讨了大气边界层(atmospheric-boundary-layer,ABL)风、壁面射流、均匀湍流三种风场作用下的屋面风压特性,比较了平均风剖面、风速、风向、湍流强度等因素对屋面风压的影响。结果表明:阀厅屋盖迎风前缘负风压最大,且控制风向角在45°左右;壁面射流风场下平均风压系数与脉动风压系数均超过大气边界层风场的结果;风速对阀厅屋盖的负风压系数均值和极值影响较小,而湍流度对风压系数的极值影响较大;大气边界风场时,JGJ/T 481—2019《屋盖结构风荷载标准》的最不利风压系数建议值偏于安全;而在壁面射流风场下,阀厅屋盖全风向最不利风压系数在所有区域都大于JGJ/T 481—2019的建议值,设计中应加以重视。

The damage of the roof of a ultra high voltage(UHV)converter station usually occurs under wind load.In order to reveal the mechanism of wind-induced failure of the roof,the wind pressure characteristics on the roof were studied in three wind fields including the atmospheric-boundary-layer(ABL)wind,wall-jet-flow and homogeneous turbulence flow.Based on wind tunnel tests,the influences of mean-wind-speed profile,wind speed,wind direction and turbulence intensity on the wind pressure were compared.The results show that the negative wind pressure on the windward edge of the roof is the largest,and the control wind direction is around 45°.In the wall-jet flow,the fluctuating wind pressure and extreme wind pressure are larger than those in the ABL flow.The wind speed has little influence on the mean and extreme value of the negative wind pressure coefficient on the roof,while the turbulence intensity has great influence on the extreme value of the wind pressure coefficient.It is also found from the result of the test that the extreme wind pressure on the roof of the UHV converter station in ABL flow suggested by the“Roof structure wind load standard”(JGJ/T 481—2019)is inclined to be safe,while the extreme wind pressure in wall-jet flow is larger than that suggested by JGJ/T 481—2019,which should pay extra attention in the design.