Abstract Flow-induced vibrations (FIV) of an equilateral triangular prism are numerically studied using the immersed boundary method in a parametric space of α = 0 ° – 60 ° and U ∗ = U ∕ f n D = 1 – 20 , with α = 0 ° ( 60 ° ) representing the configuration of one vertex facing upstream (downstream). The Reynolds number based on the effective edge length perpendicular to the incoming flow is Re = 200 and the mass ratio is m ∗ = 4 m ∕ 3 ρ D 2 = 2 . 0 . In above, U is the incoming flow velocity, f n is the natural frequency of the prism, D is the edge length of the prism, m is the prism mass and ρ is the fluid density. Three different vibration regimes, i.e., VIV at α = 0 ° – 25 ° , combined VIV and galloping at α = 30 ° – 40 ° , and galloping at α = 45 ° – 60 ° , are confirmed. In the VIV regime, the vibration amplitude is relatively small and the vibration frequency linearly increases with U ∗ , signifying the non-locked response. In the combined VIV and galloping regime, the amplitude is determined by the competition of the VIV and galloping modes, with large amplitude appearing when the galloping mode dominates. In the galloping regime, the vibration amplitude monotonically increases with U ∗ , with a lower-than-unity vibration frequency. Moreover, seven wake modes are observed in the examined α and U ∗ ranges: 2S mode, 2S(P) mode, P+S mode, P+S/2S mode, the competition mode (CM), and the galloping modes ( m i S+ n i S and mS+nS). In CM, the VIV and galloping modes compete each other. In the galloping modes, the vortices are arranged in a ‘V’ shape. The effects of the streamwise vibration on the transverse responses is significant only in the combined VIV and galloping regime.

中文翻译：

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等边三棱柱在不同攻角下的流动引起的振动

摘要 利用浸入边界法在参数空间 α = 0 ° – 60 ° 和 U ∗ = U ∕ fn D = 1 – 20 中数值研究了等边三棱柱的流致振动 (FIV)，其中 α = 0 ° ( 60 ° ) 表示一个顶点面向上游（下游）的配置。基于垂直于流入流的有效边长的雷诺数为 Re = 200，质量比为 m ∗ = 4 m ∕ 3 ρ D 2 = 2 。0 . 上式中，U 是来流速度，fn 是棱柱的固有频率，D 是棱柱的边长，m 是棱柱质量，ρ 是流体密度。确定了三种不同的振动状态，即 α = 0° – 25° 时的 VIV、α = 30° – 40° 处的组合 VIV 和疾驰，以及 α = 45° – 60° 处的疾驰。在 VIV 体制下，振动幅度相对较小，振动频率随 U* 线性增加，表示非锁定响应。在VIV和奔腾模式的组合中，振幅由VIV和奔腾模式的竞争决定，当奔腾模式占优势时出现大的振幅。在飞驰状态下，振幅随着 U ∗ 单调增加，振动频率低于统一。此外，在检查的 α 和 U* 范围内观察到七种唤醒模式：2S 模式、2S(P) 模式、P+S 模式、P+S/2S 模式、竞争模式 (CM) 和疾驰模式 (mi S+ ni S 和 mS+nS)。在CM中，VIV和奔腾模式相互竞争。在疾驰模式中，涡流以“V”形排列。