Experimental Investigation and Prediction Model of the Loads Exerted by Oblique Internal Solitary Waves on FPSO
Experimental Investigation and Prediction Model of the Loads Exerted by Oblique Internal Solitary Waves on FPSO
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DOI：
10.1007/s13344-022-0017-8
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发表时间：
2022-04
影响因子：
1.6
通讯作者：
Rui-rui Zhang;Hong-wei Wang;Ke Chen;Y. You;Shuguang Zhang;Xiaolu Xiong
中科院分区：
文献类型：
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作者：
Rui-rui Zhang;Hong-wei Wang;Ke Chen;Y. You;Shuguang Zhang;Xiaolu Xiong
利用配备双板造波器的30米长造波槽，在密度分层两层流体中产生一系列凹陷ISW，并测量了倾斜内孤立波（ISW）对固定FPSO模型的作用力。根据室内实验，采用考虑KdV、eKdV和MCC ISWs理论适用性的数值水槽来研究力分量。根据实验数据和力的构成，建立了简化的预测模型。结果表明，水平和横向载荷由两部分组成：Froude-Krylov 力，可通过对 ISW 引起的动压力沿 FPSO 润湿表面进行积分来计算；以及粘性力，可通过将摩擦系数 Cfx(Cfy)、修正系数 Kx(Ky) 与沿 FPSO 润湿表面的颗粒切向速度积分相乘获得。竖向载荷主要是竖向弗劳德-克雷洛夫力。根据实验结果，可以得出摩擦系数Cf和修正系数K回归为雷诺数Re、Keulegan-Carpenter数KC、上层深度h1/手ISW事故角α的关系。另外，水平摩擦系数Cfx与Re呈对数函数关系，横向摩擦系数Cfy与Re呈指数函数关系，修正系数Kx和Ky与KC呈幂函数关系。还根据回归公式和压力积分进行力预测。预测结果与实验结果吻合良好。最大力随 ISW 幅度线性增加。此外，上层厚度对水平力和横向力的极值有明显影响。
By using a 30-meter-long wave flume equipped with a double-plate wave maker, a series of depression ISWs were generated in a density stratified two-layer fluid and the forces exerted by oblique internal solitary waves (ISWs) on fixed FPSO model had been measured. According to the laboratory experiments, a numerical flume taken the applicability of KdV, eKdV and MCC ISWs theories in consideration was adopted to study the force components. Based on the experimental data and the force composition, the simplified prediction model was established. It was shown that the horizontal and transversal loads consisted of two parts: the Froude—Krylov force that could be calculated by integrating the dynamic pressure induced by ISW along the FPSO wetted surface, as well as the viscous force that could be obtained by multiplying the friction coefficientCfx(Cfy), correction factorKx(Ky) and the integration of particle tangential velocity along the FPSO wetted surface. The vertical load was mainly the vertical Froude—Krylov force. Based on the experimental results, a conclusion can be drawn that the friction coefficientCfand correction factorKwere regressed as a relationship of Reynolds numberRe, Keulegan—Carpenter number KC, upper layer depthh1/hand ISW accident angleα. Moreover, the horizontal friction coefficientCfxyielded the logarithmic function withRe, and transversal friction coefficientCfyobeyed the exponent function withRe, while the correction factorsKxandKyfollowed power function withKC. The force prediction was also performed based on the regression formulae and pressure integral. The predicted results agreed well with the experimental results. The maximum forces increase linearly with the ISWs amplitude. Besides, the upper layer thickness had an obvious influence on the extreme value of the horizontal and transversal forces.