考虑内流作用的缓波形立管非线性静动力分析
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摘要
考虑内流的作用,研究缓波形立管在海洋环境荷载作用下的非线性静动力力学性能。采用细长柔性杆理论,建立缓波形立管运动方程,利用有限元法进行离散,运用Newton-Raphson法和Newmark-β法分别对立管进行静动力分析,编制缓波形立管计算分析程序LWRNM,研究缓波形立管在海流、内流、浮体漂移与运动作用下的结构响应。结果表明:随着海流从x负向变成x正向和流速的增大,缓波形立管线形变缓,有效张力增大,弯曲曲率的极值减小;随着内流流速的增加,缓波形立管的固有频率下降;随着顶部浮体从近端向远端漂移,缓波形立管的有效张力增大,弯曲曲率的极值减小;纵荡和垂荡作用下,缓波形立管的顶部有效张力变化周期与浮体激励周期相同,横荡作用下,顶部有效张力变化周期为浮体激励周期的二分之一,垂荡作用下,缓波形立管顶部有效张力变化幅值最大,纵荡作用下次之,横荡作用下最小。
Effect of internal flow is taken into account in the nonlinear static and dynamic analysis of lazy wave riser in this paper.Slender rods model is used to establish the motion equation of lazy wave riser and finite element method is used to solve the motion equation.The static problem is solved by NewtonRaphson method while the dynamic response is integrated in time by Newmark-βmethod.A calculation program is developed to study lazy wave riser′s structural response behavior under the effect of current,internal flow,floating offset and motion.The results indicate that current has great influence on the shape,effective tension and curvature of lazy wave riser,and as the current varies from the directionx to+x and the current velocity increases,the shape of lazy wave riser becomes gradual,lazy wave riser′s effective tension increases and extremum of curvature decreases.With the increase of internal flow velocity,natural frequency of lazy wave riser decreases.As the position of floating changes from proximal to distal,lazy wave riser′effective tension increases and extremum of curvature decreases.The period of lazy wave riser′s effective tension is same with floating motion period under surge and heave,while the period of lazy wave riser′s effective tension is one half floating motion period under sway.The amplitude of top effective tension′s change is the largest under heave,the next is under surge,and the least is under sway.
Effect of internal flow is taken into account in the nonlinear static and dynamic analysis of lazy wave riser in this paper.Slender rods model is used to establish the motion equation of lazy wave riser and finite element method is used to solve the motion equation.The static problem is solved by NewtonRaphson method while the dynamic response is integrated in time by Newmark-βmethod.A calculation program is developed to study lazy wave riser′s structural response behavior under the effect of current,internal flow,floating offset and motion.The results indicate that current has great influence on the shape,effective tension and curvature of lazy wave riser,and as the current varies from the directionx to+x and the current velocity increases,the shape of lazy wave riser becomes gradual,lazy wave riser′s effective tension increases and extremum of curvature decreases.With the increase of internal flow velocity,natural frequency of lazy wave riser decreases.As the position of floating changes from proximal to distal,lazy wave riser′effective tension increases and extremum of curvature decreases.The period of lazy wave riser′s effective tension is same with floating motion period under surge and heave,while the period of lazy wave riser′s effective tension is one half floating motion period under sway.The amplitude of top effective tension′s change is the largest under heave,the next is under surge,and the least is under sway.
引文
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[10]Orcina Ltd.OrcaFlex Manual Version 10.0a[M].UK:Orcina Ltd,2015.
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[2]孟丹,郭海燕.深水钢悬链线立管顺流向非线性动力分析[J].船舶力学,2012,16(1):127-135.Meng D,Guo H Y.Nonlinear dynamic analysis of deepwater steel catenary riser in-line vibration[J].Journal of Ship Mechanics,2012,16(1):127-135.
[3]Yang H Z,Jiang H,Yang Q.Enhanced multi-layer fatigue-analysis approach for unbonded flexible risers[J].China Ocean Engineering,2014,28(3):363-379.
[4]Thomas B,Benirschke A,Sarkar T.Parque das conchas(BC10)steel lazy wave riser installation:Pre-abandonment,recovery and transfer challenges[C].Offshore Technology Conference.Houston:OTC,2010.
[5]Li S,Nguyen C.Dynamic response of deepwater lazy-wave catenary riser[C].DOT-Deep Offshore Technology International Conference.Houston:OTC,2010.
[6]Wang J,Duan M.A nonlinear model for deepwater steel lazy-wave riser configuration with ocean current and internal flow[J].Ocean Engineering,2015,94:155-162.
[7]孙丽萍,周佳,王佳琦.深水柔性立管的缓波型布置及参数敏感性分析[J].中国海洋平台,2011,26(3):37-42.Sun L P,Zhou J,Wang J Q.Lazy wave configuration and parameter sensitivity analysis of deepwater flexible riser[J].China Offshore Platform,2011,26(3):37-42.
[8]李艳,李欣.深水缓波形立管的非线性动力分析[J].中国造船,2014(2):92-101.Li Y,Li X.Nonlinear analysis of lazy-wave steel catenary riser in deepwater[J].Shipbuilding of China,2014,55(2):92-101.
[9]宋磊建,韩芸,付世晓,等.深水缓波形脐带缆结构响应及参数敏感性分析[J].振动与冲击,2015(19):109-114.Song L J,Han Y,Fu S X,et al.Structural responses and parameter sensitivity analysis of a lazy-wave deepwater umbilical[J].Journal of Vibration and Shock,2015(19):109-114.
[10]Orcina Ltd.OrcaFlex Manual Version 10.0a[M].UK:Orcina Ltd,2015.
[11]Garrett,D L.Dynamic analysis of slender rods[J].Journal of Energy Resources Technology.1982,104:302-306.
[12]陈海飞.深水柔性立管非线性静动力分析[D].青岛:中国海洋大学,2011.Chen H F.Nonlinear Static and Dynamic Analyses of Deepwater Flexible Risers[D].Qingdao:Ocean University of China,2011.
[13]Paidoussis M P.Fluid-Structure Interactions:Slender Structures and Axial Flow[M].London:Academic Press,1998:71-76.