两模块半潜平台波浪漂移力的频域分析
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摘要
波浪漂移力对半潜平台系泊系统的设计十分重要,为了研究不同水深、不同浪向下两模块半潜平台受到的平均漂移力,文章利用势流理论及波浪绕射/辐射理论对两模块半潜平台所处流场的速度势进行了分析。并应用近场法求解了两模块半潜平台所受到的平均漂移力,对不同水深、不同浪向下半潜平台模块的平均漂移力进行了对比分析,并与单模块半潜平台受到的平均漂移力进行了对比。研究结果表明,半潜平台模块间的水动力干扰对半潜平台模块受到的平均漂移力有较大的影响;水深吃水比大于5时不同水深条件下得到的平均漂移力与无限水深条件下的结果基本相同,当水深吃水比小于5时水深对平均漂移力的影响较为显著,此时随着水深变浅半潜平台的平均漂移力与无限水深条件下的差异增大;中高频段半潜平台的平均漂移力对浪向角的改变较为敏感。
Wave drift force is the main exciting force causing the low frequency oscillation of a mooring system therefore needs to be evaluated accurately in the design process of the mooring system. This paper presents a study on the mean drift forces on two connected semi-submersible platform modules in different water depth and different wave directions. The linearized three dimensional diffraction/radiation theory are used to analyse the wave potential, and the mean wave drift forces and moments on each semi-submersible module are computed using the near-field method. Comparative analyses are conducted for the mean drift forces and moments on semi-submersible modules in the different water depths and different wave directions, as well as the effect of the hydrodynamic interaction between the two modules. The results show that the hydrodynamic interaction has a significant influence on the mean drift forces on both semi-submersible modules, it is also found that the water depth does not have much impact on the mean wave drift force unless the ratio of water depth to draft became lower than 5. The results also show that the mean drift force is only sensitive to the wave direction in the medium and high wave frequency domain.
Wave drift force is the main exciting force causing the low frequency oscillation of a mooring system therefore needs to be evaluated accurately in the design process of the mooring system. This paper presents a study on the mean drift forces on two connected semi-submersible platform modules in different water depth and different wave directions. The linearized three dimensional diffraction/radiation theory are used to analyse the wave potential, and the mean wave drift forces and moments on each semi-submersible module are computed using the near-field method. Comparative analyses are conducted for the mean drift forces and moments on semi-submersible modules in the different water depths and different wave directions, as well as the effect of the hydrodynamic interaction between the two modules. The results show that the hydrodynamic interaction has a significant influence on the mean drift forces on both semi-submersible modules, it is also found that the water depth does not have much impact on the mean wave drift force unless the ratio of water depth to draft became lower than 5. The results also show that the mean drift force is only sensitive to the wave direction in the medium and high wave frequency domain.
引文
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[13]Nallayarasu S,Prasad P S.Hydrodynamic response of spar and semi-submersible interlinked by a rigid yoke-Part I:regular waves[J].Ships and Offshore Structures,2012,7(3):297-309.
[14]Nallayarasu S,Prasad P S.Hydrodynamic response of spar and semi-submersible interlinked by a rigid yoke-Part II:random waves[J].Ships and Offshore Structures,2012,7(2):133-141.
[2]李良碧,曹剑锋,顾海英,等.基于直接计算方法的海上超大型浮式结构物单模块强度分析[J].船舶工程,2015,37(11):67-71.Li L B,Cao J F,Gu H Y,et al.Strength analysis of single module of VLFS based on direct calculating method[J].Ship Engineering,2015,37(11):67-71.
[3]吴东伟,顾学康,祁恩荣.半潜式平台全寿命期极值载荷的确定[J].舰船科学技术,2011,33(4):39-47.Wu D W,Gu X K,Qi E R.Determination of extreme wave loads for semi-submersible during the whole life[J].Ship Science and Technology,2011,33(4):39-47.
[4]Nallayarasu S,Prasad P S.Hydrodynamic response of spar and semi-submersible interlinked by a rigid yoke-Part I:regular waves[J].Ships and Offshore Structures,2012,7(3):297-309.
[5]王科,贺大川,张志强.半潜式钻井平台波浪散射力与运动响应分析[J].船舶力学,2013,17(5):478-487.Wang K,He D C,Zhang Z Q.Wave exciting force and motion response of semi-submersible[J].Journal of Ship Mechanics,2013,17(5):478-487.
[6]姜宗玉,崔锦,董刚,等.不规则波中动力定位半潜平台慢漂运动研究[J].中国海洋平台,2015,30(3):89-94.Jiang Z Y,Cui J,Dong G,et al.An investigation on slow drift motions of a DP semi-submersible platform[J].China Offshore Platform,2015,30(3):89-94.
[7]王科,贺大川,施鹏飞,等.半潜式采油平台波浪漂移力分析研究[J].船舶力学,2014,18(4):406-412.Wang K,He D C,Shi P F,et al.Wave drift forces of semi-submersible[J].Journal of Ship Mechanics,2014,18(4):406-412.
[8]Clauss G,Stempinski F,Dudek M,et al.Water depth influence on wave-structure-interaction[J].Ocean Engineering,2009,36:1396-1403.
[9]霍发力.水深对半潜式平台水动力性能及波浪载荷的影响[J].船舶工程,2014,36(6):100-104.Huo F L.Influence of water depth on hydrodynamic performance and wave load of semi-submersible platform[J].Ship Engineering,2014,36(6):100-104.
[10]田超,丁军,杨鹏.岛礁波浪环境下浮式结构物的动响应预报[J].船舶力学,2014,18(11):1284-1291.Tian C,Ding J,Yang P.Prediction of dynamic responses of floating structures under wave environment near islands and reefs[J].Journal of Ship Mechanics,2014,18(11):1284-1291.
[11]Newman J N.Efficient hydrodynamic analysis of very large floating structures[J].Marine Structure,2005,18:169-180.
[12]杨鹏,顾学康.超大型浮体模块水弹性响应和结构强度分析[J].船舶力学,2015,19(5):553-565.Yang P,Gu X K.Analysis on the hydroelastic responses and structural strength of VLFS module[J].Journal of Ship Mechanics,2015,19(5):553-565.
[13]Nallayarasu S,Prasad P S.Hydrodynamic response of spar and semi-submersible interlinked by a rigid yoke-Part I:regular waves[J].Ships and Offshore Structures,2012,7(3):297-309.
[14]Nallayarasu S,Prasad P S.Hydrodynamic response of spar and semi-submersible interlinked by a rigid yoke-Part II:random waves[J].Ships and Offshore Structures,2012,7(2):133-141.