吸力锚飞溅区吊装入水速度影响分析

Analysis of the influence of water entry velocity on the suction anchor lowering operation in the splash zone

针对吸力锚吊装作业跨越飞溅区时的动力学问题,本文基于雷诺时间平均Navier-Stokes(RANS)方程,采用流体体积函数法求解多相流,对在不规则波浪中不同吊装速度下缆绳拉力与吊物运动进行了分析。通过数值结果与工程实测数据进行对比,验证数学模型的准确性,并研究动态影响因子、特征拉力和运动参数随傅汝德数和速度的变化。结果表明:在实际吊装速度为0.1~0.7 m/s时,即使缆绳的拉力和结构物的运动呈非线性变化,吊装作业中缆绳也不会发生松弛;随着吊装速度的增加,纵向和横向位移的均值增加,最大可达-1.204 m。结构物的横摇和纵摇加剧,而艏摇减弱,但吊装速度最大时艏摇角仍大于0.25°。研究表明:在吊装作业中应当充分考虑吸力锚的水平面非对称运动,仅对其垂向运动进行仿真是不合理的。

The dynamics of suction anchors during the lifting operation over a splash zone are investigated,sling tension and structure motion in an irregular wave are analyzed using the Reynolds-Averaged Navier-Stokes equation,and the volume of fluid method is used to solve the multiphase flow.The accuracy of the numerical model is validated by comparing numerical results to engineering measurements.The dynamic effect,the characteristic tension force,and the motion parameters that change with Froude number and velocity are also investigated.The results show that when the lowering velocity is between 0.1 and 0.7 m/s,the slings do not sag,even when the sling tension and structure motion parameters vary nonlinearly.The average value of longitudinal and lateral translations increases with decreasing velocity,reaching-1.024 m at its maximum.The roll and pitch motions deteriorate,while the yaw motion weakens,but the yaw angle remains greater than 0.25°at the maximum lowering velocity.The horizontal asymmetric motion of the suction anchor should be fully considered in the lowering operation,and it is unreasonable to only simulate its vertical motion.