海流作用下子母管结构横向涡激振动

基于量纲分析,设计模型试验研究稳态海流作用下子母管结构的横向涡激振动。通过对结构横向振动位移、水动力载荷和流场速度的同步测量分析,研究子母管结构横向涡激振动幅值和频率随约减速度的变化规律以及母管的水动力特性。实验结果表明,子母管间距比和质量比对管道横向振动和水动力有较大影响。在管间距比为0.1～0.5范围内,子母管结构涡激振动存在明显的不对称性。随着子母管间距比的减小,结构横向最大振幅增大,涡激振动的约减速度范围变宽;随着质量比的增大,涡激振动的约减速度范围变窄。母管的平均阻力系数随子母管间距比的增大单调递减,而平均升力系数则呈现非单调变化的特征。

Vortex-induced transverse vibration of piggyback pipelines in steady current

Based on dimensionless analyses,the vortex-induced transverse vibration of piggyback pipelines under the action of ocean currents is investigated experimentally with a newly designed facility.In the experiments,the transverse vibration displacement of the piggyback pipelines,the hydrodynamic pressure around the primary pipe,and the inlet flow velocity are measured synchronously.The variations of vibration amplitude and frequency responses with the reduced flow velocity,and the hydrodynamic pressure on the primary pipe are studied,respectively.Experimental results indicate that the dimensionless gap-to-diameter ratio and the mass ratio have much effect on the transverse vibrations of piggyback pipelines.The asymmetry of the transverse vibration configuration for piggyback pipelines was observed,especially for the examined gap-to-diameter ratio range from 0.1 to 0.5.With the decrease of the gap-to-diameter ratio,the maximum value of transverse vibration amplitude increases and the range of the reduced flow velocity gets wider.With the increase of the mass ratio,the range of the reduced flow velocity gets narrower.The mean drag coefficient decreases monotonously with the increase of the gap-to-diameter ratio,while the variation of the mean lift coefficient with the gap-to-diameter ratio is not monotonous.