摘要
非平稳极端风由强对流导致,因此与良态风相比具有强加速度、高相关性的特征。传统边界层风洞采用尖劈、粗糙元或格栅产生湍流风场,难以有效模拟极端风的大尺度突变风特征。对加拿大西安大略大学直流式风洞进行改造,通过开闭挡板快速改变流动方向,在试验段产生较大加速度的突增/突减风以及一维正弦脉动风。经测试,改造后风洞可有效地模拟高相关性极端风的突增、突降特性,并可产生频谱能量集中的一维正弦脉动风。突增风下的闭口箱梁断面表面风压将产生由风场时变静压导致的极值,断面极值风压分布为均匀流下绕流风压分布及梯度压强的叠加。
Nonstationary extreme winds are caused by strong convection,thus have high acceleration and high correlation compared to synoptic winds.Wedges,roughness cubes,and grids are used in traditional boundary layer wind tunnels to generate turbulent wind fields.With these arrangements,it is hard to simulate the largescale gust of the extreme winds.In this paper,the straight wind tunnel at Western University in Canada is modified to generate such large-scale gust winds.The flow rapidly changes direction due to the opening and shutting blades,thus high acceleration/deceleration winds and sinusoidal winds are generated through the test chamber.Tests show that the modified wind tunnel can simulate high-correlated sudden-increase/decrease properties of extreme winds,and can also generate sinusoidal oscillation winds that concentrate energy in the frequency domain.The time histories of the surface pressures on a closed-box girder under sudden-increase winds have extreme values caused by the time-varying static pressure of the wind fields.The distribution of the extreme wind pressure under sudden-increase wind is the mixture of the mean pressure distribution under uniform flow and the gradient pressure under sudden-increase winds.
作者
赵诗宇
陈旭
葛耀君
ZHAO Shiyu;CHEN Xu;GE Yaojun(State Key Laboratory of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;School of Civil Engineering,Shanghai Normal University,Shanghai 201418,China)
出处
《结构工程师》
2022年第4期105-112,共8页
Structural Engineers
基金
国家自然科学基金面上项目(51978527)。
关键词
突增风速
正弦脉动风
闭口箱梁
非平稳效应
sudden-increase winds
sinusoidal winds
closed-box girder
nonstationary effect
