基于非线性数学模型的半潜式平台共振运动特性研究

Study on motion resonance features of semi-submersible platform based on nonlinear mathematical model

共振运动是深海浮式平台设计的关键考虑因素之一,对海洋平台的作业具有重要影响。采用半潜式平台运动的非线性耦合数学模型,考虑浮筒和横撑出入水以及垂荡、横摇和纵摇运动耦合对平台浮力和恢复力的影响,研究半潜式平台非线性共振运动特性,以及不规则波浪参数对运动的影响。研究表明:在非线性耦合运动和浮力变化的影响下,半潜式平台纵摇和垂荡运动的固有周期会随运动幅值的增大而逐渐减小,且最终趋于稳定,对纵摇运动周期的影响更为显著;非线性效应会使半潜式平台产生显著的低频纵摇共振响应,以及共振频率漂移的现象,且受随机种子和波浪周期的影响较小。

Motion resonance is crucial for the safe design and operation of deepwater floating platform.In this study, the motion resonance features of semi-submersible platform are investigated, based on a nonlinear coupling mathematical model, considering the effects of pontoons and bracings and the coupling of heave, roll and pitch motions on the buoyancy and restoring force.The effect of irregular wave parameters is also investigated.The results indicate that the natural periods of the pitch and heave of the semi- submersible platform vary with the amplitude of motion by considering nonlinear coupling and buoyancy variation.When the amplitude of motion increases, the natural period gradually decreases and eventually becomes stable.The significant low- frequency pitch resonance, and the deviation of the resonance frequency from the natural pitch frequency due to the nonlinearities are observed.In addition, wave seed and wave period have little influence on the motion resonance.