考虑旋转自由度的涡激振动数值模拟研究
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摘要
当前,对于涡激振动的研究主要集中在单自由度或双自由度弹性固定的圆柱上,分析其振幅、频率、相位等振动响应随约化速度的变化规律。对于考虑旋转自由度的涡激振动,由于受到实验装置以及测量手段等条件的制约,相关的研究并不多见。基于OpenFoam软件,对考虑旋转自由度的低质量比圆柱涡激振动响应特性进行数值模拟研究。参照Williamson(2004)的实验,对双自由度低质量比圆柱进行数值模拟,在相同的边界条件下,对圆柱增加旋转自由度并进行数值模拟。通过对两种工况下涡激振动响应的对比分析,可以得出以下结论:圆柱在涡激振动过程中会发生艏摇现象。同时,艏摇现象的发生会对其振幅起小幅的抑制作用。此外,艏摇频率与横向振动频率一致,且艏摇幅度与尾涡形式有关。
At present,the vortex induced vibration( VIV) studies are mainly focused on circular cylinders fixed elastically with one DOF or 2-DOF to analyze change laws of their amplitude,frequency and phase etc. vibration responses with variation of the reduced velocity. For the VIV considering rotational-DOF,the relevant studies are not many due to the restriction of test devices and detection methods. Here,based on the software Open Foam,the VIV response features of circular cylinders with a lower mass ratio and rotational-DOF were simulated numerically. Firstly,according to Williamson( 2004) 's test,the VIV response of a cylinder with two-DOF was simulated,then a rotationalDOF was added and the similar numerical simulation for this cylinder under the same boundary conditions was conducted.Through the contrastive analysis of these two VIV responses,it was concluded that the cylinder's yaw phenomenon occurs in its VIV process; at the same time,the yaw phenomenon slightly suppresses the VIV amplitude; in addition,the yaw frequency is equal to the cylinder's lateral vibration frequency,and the yaw amplitude is related to the form of tail vortex.
At present,the vortex induced vibration( VIV) studies are mainly focused on circular cylinders fixed elastically with one DOF or 2-DOF to analyze change laws of their amplitude,frequency and phase etc. vibration responses with variation of the reduced velocity. For the VIV considering rotational-DOF,the relevant studies are not many due to the restriction of test devices and detection methods. Here,based on the software Open Foam,the VIV response features of circular cylinders with a lower mass ratio and rotational-DOF were simulated numerically. Firstly,according to Williamson( 2004) 's test,the VIV response of a cylinder with two-DOF was simulated,then a rotationalDOF was added and the similar numerical simulation for this cylinder under the same boundary conditions was conducted.Through the contrastive analysis of these two VIV responses,it was concluded that the cylinder's yaw phenomenon occurs in its VIV process; at the same time,the yaw phenomenon slightly suppresses the VIV amplitude; in addition,the yaw frequency is equal to the cylinder's lateral vibration frequency,and the yaw amplitude is related to the form of tail vortex.
引文
[1]KANG Zhuang,NI Wenchi,SUN Liping.An experimental investigation of two-degrees-of-freedom VIV trajectories of a cylinder at different scales and natural frequency ratios[J].Ocean Engineering,2016,126:187-202.
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[13]KANG Z,NI W,SUN L.A numerical investigation on capturing the maximum transverse amplitude in vortex induced vibration for low mass ratio[J].Marine Structures,2017,52:94-107.
[14]林琳,王言英.不同湍流模型下圆柱涡激振动的计算比较[J].船舶力学,2013,17(10):1115-1125.LIN Lin,WANG Yanying.Comparison between different turbulence models on vortex induced vibration of circular cylinder[J].Journal of Ship Mechanics,2013,17(10):1115-1125.
[15]谷家扬,杨建民,肖龙飞.两种典型立柱截面涡激运动的分析研究[J].船舶力学,2014,18(10):1184-1194.GU Jiayang,YANG Jianmin,XIAO Longfei.Study on vortex induced motion of two typical different cross-section columns[J].Journal of Ship Mechanics,2014,18(10):1184-1194.
[16]PAN Z Y,CUI W C,MIAO Q M.Numerical simulation of vortex-induced vibration of a circular cylinder at low massdamping using RANS code[J].Journal of Fluids&Structures,2007,23(1):23-37.
[17]WILLIAMSON C.A high-amplitude 2T mode of vortexinduced vibration for a light body in XY motion[J].European Journal of Mechanics-B/Fluids,2004,23(1):107-114.
[2]KHALAK A,WILLIAMSON C H K.Dynamics of a hydro elastic cylinder with very low mass and damping[J].Journal of Fluids and Structures,1996,10(5):455-472.
[3]JAUVTIS N,WILLIAMSON C H K.The effect of two degrees of freedom on vortex-induced vibration at low mass and damping[J].Journal of Fluid Mechanics,2004,509(509):23-62.
[4]KHALAK A,WILLIAMSON C H K.Motions,forces and mode transitions in vortex-vibrations at lowmass-damping[J].Journal of Fluids and Structures,1999,13:813-851.
[5]GOVARDHAN R N,WILLIAMSON C H K.Vortex-induced vibrations of a sphere[J].Journal of Fluid Mechanics,2005,531(531):11-47.
[6]NAIK S N,VENGADESAN S,PRAKASH K A.Numerical study of fluid flow past a rotating elliptic cylinder[J].Journal of Fluids&Structures,2017,68:15-31.
[7]LAM K M.Vortex shedding flow behind a slowly rotating circular cylinder[J].Journal of Fluids&Structures,2009,25(2):245-262.
[8]WILDE J D.Model tests on the vortex induced motions of the air can of a free standing riser system in current[C]∥Proceedings of the Deep Offshore Technology Conference.Stavanger:DOTC,2007.
[9]李鹏.浮力筒自由涡激运动试验研究[D].哈尔滨:哈尔滨工程大学,2015.
[10]MENTER F R.Two-equation eddy-viscosity turbulence models for engineering applications[J].Aiaa Journal,2012,32(8):1598-1605.
[11]CLOETE S,JOHANSEN S T,AMINI S.Grid independence behaviour of fluidized bed reactor simulations using the two fluid model:detailed parametric study[J].Powder Technology,2015,289:65-70.
[12]MORAGUES GINARD M,BERNARDINO G,VZQUEZ M,et al.Fourier stability analysis and local courant number of the preconditioned variational multiscale stabilization(PVMS)for euler compressible flow[J].Computer Methods in Applied Mechanics&Engineering,2015,301:28-51.
[13]KANG Z,NI W,SUN L.A numerical investigation on capturing the maximum transverse amplitude in vortex induced vibration for low mass ratio[J].Marine Structures,2017,52:94-107.
[14]林琳,王言英.不同湍流模型下圆柱涡激振动的计算比较[J].船舶力学,2013,17(10):1115-1125.LIN Lin,WANG Yanying.Comparison between different turbulence models on vortex induced vibration of circular cylinder[J].Journal of Ship Mechanics,2013,17(10):1115-1125.
[15]谷家扬,杨建民,肖龙飞.两种典型立柱截面涡激运动的分析研究[J].船舶力学,2014,18(10):1184-1194.GU Jiayang,YANG Jianmin,XIAO Longfei.Study on vortex induced motion of two typical different cross-section columns[J].Journal of Ship Mechanics,2014,18(10):1184-1194.
[16]PAN Z Y,CUI W C,MIAO Q M.Numerical simulation of vortex-induced vibration of a circular cylinder at low massdamping using RANS code[J].Journal of Fluids&Structures,2007,23(1):23-37.
[17]WILLIAMSON C.A high-amplitude 2T mode of vortexinduced vibration for a light body in XY motion[J].European Journal of Mechanics-B/Fluids,2004,23(1):107-114.