Numerical simulation for flow-induced vibration of regular triangular column under different angles of attack

Here, the 2D numerical simulation for flow-induced vibration of a regular triangular column under different angles of attack was studied by using the embedded iterative immersed boundary method. The angle of attack range was α=0°-60° (a vertex of regular triangular column faces flow when α=60°), Reynolds number was Re=100, the mass ratio was m*=5, and the reduced velocity was Ur=2-20. The variation of cross flow amplitude, vibration frequency, hydrodynamic coefficient, phase difference between lift and displacement and wake vortex mode with change of reduced velocity under different angles of attack were analyzed in detail. The results showed that the triangular column vibration has 3 different vibration modes of the combined vortex-induced vibration(VIV) and galloping mode at α=0°-15°, the separated VIV and galloping mode at α=20.0°-22.5°, and the VIV mode at α=25°-60°; vibration characteristics of the triangular column under 3 modes are described in detail at three attack angles α=0°, 20° and 60°, respectively; although the triangular column is symmetric about incoming flow direction when α=0°, its balanced position is offset at some reduced velocities, this phenomenon is related to occurrence of even harmonic components in lift; the attack angle range of galloping is obtained by using the quasi-steady state analysis, this range agrees better with that of numerical simulation, so the quasi steady state analysis can accurately predict the attack angle range of triangular column galloping. © 2022, Editorial Office of Journal of Vibration and Shock. All right reserved.