浮式液化天然气储存装置单点系泊水动力特性分析

Investigation on hydrodynamic performance of an SPM FLNG

针对设计的计划作业于南海1 500 m水深海域的浮式液化天然气储存装置(FLNG),开展了水池模型试验和数值计算分析,模拟了南海的环境条件,采集了单点系泊下的FLNG船体六自由度运动以及系泊锚链顶端载荷时历,在频域和时域范围对FLNG水动力特性以及舱内液体晃荡对FLNG的影响进行了研究,结果表明:在频域分析中,舱内液体晃荡使得FLNG的横摇运动在波频范围表现出较固体装载更小的运动响应;在时域分析中,舱内液体晃荡在南海一年一遇海况下加剧了FLNG的横摇运动;在百年一遇海况下削弱了该型FLNG的横摇运动;舱内液体晃荡对FLNG的纵摇、垂荡、纵荡、横荡以及艏摇运动影响较小。在此基础上,提出了系泊系统优化方案并进行了数值计算研究,认为在满足一定安全裕度的条件下能够通过减少系泊锚链数目显著降低建造成本,这对现阶段FLNG的自主设计提供了一定的参考依据。

This paper conducted an investigation on hydrodynamic performance of a floating liquefied natural gas system （FLNG） through model test method and numerical calculation method. The FLNG was designed to serve in South China Sea with the water depth on 1 500 m by a single point mooring （SPM） system. The envi- ronmental conditions were simulated in the model test, and six-degree of freedom movement and time series of top tension of mooring lines of SPM FLNG have been acquired. The investigations on hydrodynamic perform- ance of SPM FLNG and the effects of liquid sloshing in cabin on FLNG in both frequency and time domain have been conducted. In frequency domain, the roll motion of FLNG decreases under the effects of liquid slos- hing in cabin, comparing with the results from the solid loading condition. In time domain, the effects of liquid sloshing in cabin increases the roll motion in 1 year return sea state of South China Sea but decreases the roll motion of this FLNG in 100 years return sea state. The liquid sloshing in cabin presents limited influences on the motions of pitch, heave, surge and sway of the FLNG. An optimization of mooring system has been pro- posed and investigated through numerical calculation. This optimization can significantly reduce the construc- tion cost through reducing the number of mooring lines, while satisfying certain safety factor. This paper will provide useful suggestions for the design of FLNG in the near future.