不同攻角三角柱双自由度风致振动响应特性研究

Two-degrees of Freedom Wind-induced Vibration of Equilateral Triangular Prism Under Different Attack Angles

结构的风致振动现象在自然界和工程应用中极其常见,本文针对等边三角柱风致振动问题,采用二维非稳态数值方法研究了不同来流攻角对振动响应的影响。结果表明,三角柱在低攻角下垂直流向的振幅极低且随折减速度U*的增加变化不大;当攻角α_(0)≥40°时,三角柱垂直流向振幅随U^(*)的增加而上升,可观察到初始分支和上部分支。除α_(0)=10°外,三角柱振动折减频率f_(y)^(*)随U^(*)的增加先缓慢上升(3≤U^(*)≤8),后稳定于1.0附近,并可捕捉到频率锁定现象。α_(0)=40°时,随着U^(*)的增加三角柱尾迹由双列涡街向单列涡街的转变。

Wind-induced vibration(WIV)is very common in nature and engineering applications.In this work,the effect of different attack angles on WIV responses of equilateral triangular prism was investigated by two-dimensional unsteady numerical method.The results show that the amplitude of prism in cross-flow direction is extremely low for low attack angles and almost doesn’t change with the rise of the reduced velocity(U^(∗));when α_(0)≥40°,the amplitude in cross-flow direction increases with the rise of U^(∗),the initial branch and the upper branch can be obtained.Except for α_(0)=10°,the reduced frequency(f_(y)^(∗))slowly increases first(3≤U^(∗)≤8)and then stabilizes around 1.0 with the rise of U^(∗),lock-in phenomenon can be observed.When α_(0)=40°,the wake of prism transforms from two parallel vortex streets to single row of vortex street with the rise of U^(∗).