Mean Drag Force of Flexible Riser Under Bidirectionally Sheared Flow

doi:10.16183/j.cnki.jsjtu.2023.124

Abstract

Abstract:

There exists a special bidirectionally sheared flow field due to solitons in the South China Sea. An experimental study of the mean drag force of a flexible riser undergoing vortex-induced vibration under bidirectionally sheared flow is conducted. Modal analysis and the beam theory are applied to processing the strain signal measured in the experiment to obtain the mean drag force. The initial displacement, mean drag force, and mean drag coefficient are investigated, and the amplification of the mean drag coefficient is confirmed under bidirectionally sheared flow with comparable amplification to linear shear flow. Meanwhile, a unique phenomenon that the shear force reaches an extreme value in the center of the riser under bidirectionally sheared flow is found in the experiment. The shear force coefficient is proposed and fitted to obtain an empirical formula for the extreme value of the central shear force of the flexible riser under bidirectionally sheared flow, which will provide external load input for the design of the riser in the South China Sea.

Key words: vortex-induced vibration, bidirectionally sheared flow, mean drag, shear force

CLC Number:

P756.2

FU Xuepeng, FU Shixiao, ZHANG Mengmeng, XU Yuwang, REN Haojie, SUN Tongxiao. Mean Drag Force of Flexible Riser Under Bidirectionally Sheared Flow[J]. Journal of Shanghai Jiao Tong University, 2024, 58(11): 1637-1643.

Figures/Tables 18

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Tab.1

Parameters of model of test riser

参数	取值
模型长度,L/m	7.64
外径,D/mm	28.41
单位长度质量, $m -$ /(kg·m^-1)	1.24
弯曲刚度,EI/(N·m²)	58.60
拉伸刚度,EA/kN	940
预张力,T_pre/N	980
阻尼比,ζ/%	2.58

Tab.1

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References 22

[1]	WILLIAMSON C H K, GOVARDHAN R. Vortex-induced vibrations[J]. Annual Review of Fluid Mechanics, 2004, 36: 413-455.
[2]	SARPKAYA T. A critical review of the intrinsic nature of vortex-induced vibrations[J]. Journal of Fuids and Structures, 2004, 19(4): 389-447.
[3]	顾继俊, 马天麒, 陈磊磊, 等. 内输高温高压流体海底悬跨管道的非线性涡激振动响应分析[J]. 石油科学通报, 2022, 7 (1): 116-126.
	GU Jijun, MA Tianqi, CHEN Leilei, et al. Nonlinear dynamic response of suspended span pipe conveying high temperature and high pressure flow[J]. Petroleum Science Bulletin, 2022, 7 (1): 116-126.
[4]	YIN D, PASSANO E, JIANG F, et al. State-of-the-art review of vortex-induced motions of floating offshore wind turbine structures[J]. Journal of Marine Science and Engineering, 2022, 10(8): 1021.
[5]	高云, 郑文龙, 熊友明, 等. 不同表面粗糙度下圆柱体涡激振动响应特性数值研究[J]. 上海交通大学学报, 2018, 52(4): 419-428. doi: 10.16183/j.cnki.jsjtu.2018.04.006
	GAO Yun, ZHENG Wenlong, XIONG Youming, et al. Numerical study of the vortex induced vibrations of a circular cylinder with different degrees of surface roughness[J]. Journal of Shanghai Jiao Tong University, 2018, 52(4): 419-428.
[6]	ASSI G R S, CRESPI T, GHARIB M. Novel geometries of serrated helical strakes to suppress vortex-induced vibrations and reduce drag[J]. Applied Ocean Research, 2022, 120: 103034.
[7]	FENG Y L, CHEN D Y, LI S W, et al. Vortex-induced vibrations of flexible cylinders predicted by wake oscillator model with random components of mean drag coefficient and lift coefficient[J]. Ocean Engineering, 2022, 251: 110960.
[8]	ZHAO B, ZHANG M, FU S, et al. Drag coefficients of double unequal-diameter flexible cylinders in tandem undergoing vortex/wake-induced vibrations[J]. Ocean Engineering, 2023, 270: 113642.
[9]	TOGNARELLI M A, SLOCUM S T, FRANK W R, et al. VIV response of a long flexible cylinder in uniform and linearly sheared currents[C]//Offshore Technology Conference. Houston, USA: One Petro, 2004: OTC-16338-MS.
[10]	TRIM A D, BRAATEN H, LIE H, et al. Experimental investigation of vortex-induced vibration of long marine risers[J]. Journal of Fluids and Structures, 2005, 21(3): 335-361.
[11]	SONG L, FU S, CAO J, et al. An investigation into the hydrodynamics of a flexible riser undergoing vortex-induced vibration[J]. Journal of Fluids and Structures, 2016, 63: 325-350.
[12]	SONG L, FU S, DAI S, et al. Distribution of drag force coefficient along a flexible riser undergoing VIV in sheared flow[J]. Ocean Engineering, 2016, 126: 1-11.
[13]	ZHANG M, FU S, SONG L, et al. Hydrodynamics of flexible pipe with staggered buoyancy elements undergoing vortex-induced vibrations[J]. Journal of Offshore Mechanics and Arctic Engineering, 2018, 140(6): 061805.
[14]	谢波涛, 雷方辉. 南海流花海域内孤立波特征分析[J]. 中国造船, 2013, 54 (Sup. 2): 2): 210-218.
	XIE Botao, LEI Fanghui. Characteristics of internal solitons at Liuhua Area in the South China Sea[J]. Shipbuliding of China, 2013, 54 (Sup. 2): 210-218.
[15]	FU X, FU S, REN H, et al. Experimental investigation of vortex-induced vibration of a flexible pipe in bidirectionally sheared flow[J]. Journal of Fluids and Structures, 2022, 114: 103722.
[16]	LIE H, BRAATEN H, JHINGRAN V G, et al. Comprehensive riser VIV model tests in uniform and sheared flow[C]//International Conference on Offshore Mechanics and Arctic Engineering. Rio de Janeiro, Brazil: American Society of Mechanical Engineers, 2012, 44922: 923-930.
[17]	LIE H, KAASEN K E. Modal analysis of measurements from a large-scale VIV model test of a riser in linearly sheared flow[J]. Journal of Fluids and Structures, 2006, 22(4): 557-575.
[18]	SONG L, FU S, ZENG Y, et al. Hydrodynamic forces and coefficients on flexible risers undergoing vortex-induced vibrations in uniform flow[J]. Journal of Waterway, Port, Coastal, and Ocean Engineering, 2016, 142(4): 04016001.
[19]	CHAPLIN J R, BEARMAN P W, HUARTE F J H, et al. Laboratory measurements of vortex-induced vibrations of a vertical tension riser in a stepped current[J]. Journal of Fluids and Structures, 2005, 21(1): 3-24.
[20]	宋磊建, 付世晓, 于大鹏, 等. 剪切流下发生涡激振动的柔性立管阻力特性研究[J]. 力学学报, 2016, 48(2): 300-306. doi: 10.6052/0459-1879-15-309
	SONG Leijian, FU Shixiao, YU Dapeng, et al. Investigation of drag forces for flexible risers undergoing vortex-induced vibration in sheared flow[J]. Chinese Journal of Theoretical and Applied Mechanics, 2016, 48(2): 300-306. doi: 10.6052/0459-1879-15-309
[21]	胡伟杰, 刘正礼, 陈彬. 南海内波流对深水钻井的影响及对策[J]. 石油钻采工艺, 2015, 37(1): 160-162.
	HU Weijie, LIU Zhengli, CHEN Bin. Impacts of internal waves in the South China Sea on deepwater drilling safety and corresponding countermeasures[J]. Oil Drilling & Production Technology, 2015, 37(1): 160-162.
[22]	宋玲安. 海洋内波流对深水钻井影响技术分析[J]. 石化技术, 2021, 28(7): 67-68.
	SONG Ling’an. Analysis on the influence of ocean wave flow on deepwater drilling[J]. Petrochemical Industry Technology, 2021, 28(7): 67-68.