Synergetic Analysis and Possible Control of Vortex-Induced Vibrations in a Fluid-Conveying Steel Catenary Riser  

作　　者：MENG Dan ZHU Chongji 

机构地区：[1]School of Architectural Engineering, Qingdao Agricultural University [2]School of Civil Engineering and Architectural, University of Jinan

出　　处：《Journal of Ocean University of China》2015年第2期245-254,共10页中国海洋大学学报（英文版）

基　　金：Financial support from the China Postdoctoral Science Foundation Fund (Grant No.2013M531563);the Qingdao Agricultural University High-Level Talents Research Fund (Grant No. 631424)is gratefully acknowledged

摘　　要：This work aimed to demonstrate possibilities for both active and passive control of the vortex-induced vibration and fatigue life of steel catenary risers via an analysis of the self-organization and evolution of the structural vibration based on synergetic theory. An analysis of the complex interrelated and synergistic relationship between the order parameter and the fast variable was performed, and the master equation of the nodal displacements was established as the order parameter for the evolution of the riser's structural vibration. Passive control methods include modifying the structure's elastic modulus, the internal fluid velocity, the top tension and the structural damping ratio, while an active control involves adjusting the external flow rate. Optimized parameters were obtained by analyzing the non-steady state solution of the master equation. The results show that the fatigue life greatly increases as the riser's elastic modulus decreases. In contrast, the fatigue life decreases with an increase of the internal fluid velocity. With an increase of the top tension, the vibration amplitudes and the number of modes may decrease, resulting in fewer bending stress cycles and a longer fatigue life. Furthermore, the structural damping ratio should be as large as possible. Finally, an active and passive control of the riser structure's response to vortex-induced vibration and its fatigue life can be achieved by carefully modifying the parameters mentioned above. The results may provide a theoretical framework for engineering practice concerning the design and control of steel catenary riser structures which are affected by vortex-induced vibration.This work aimed to demonstrate possibilities for both active and passive control of the vortex-induced vibration and fatigue life of steel catenary risers via an analysis of the self-organization and evolution of the structural vibration based on syner- getic theory. An analysis of the complex interrelated and synergistic relationship between the order parameter and the fast variable was performed, and the master equation of the nodal displacements was established as the order parameter for the evolution of the riser＇s structural vibration. Passive control methods include modifying the structure＇s elastic modulus, the internal fluid velocity, the top tension and the structural damping ratio, while an active control involves adjusting the external flow rate. Optimized parameters were obtained by analyzing the non-steady state solution of the master equation. The results show that the fatigue life greatly in- creases as the riser＇s elastic modulus decreases. In contrast, the fatigue life decreases with an increase of the internal fluid velocity. With an increase of the top tension, the vibration amplitudes and the number of modes may decrease, resulting in fewer bending stress cycles and a longer fatigue life. Furthermore, the structural damping ratio should be as large as possible. Finally, an active and passive control of the riser structure＇s response to vortex-induced vibration and its fatigue life can be achieved by carefully modify- ing the parameters mentioned above. The results may provide a theoretical framework for engineering practice concerning the design and control of steel catenary riser structures which are affected by vortex-induced vibration.

关 键 词：steel catenary riser vortex-induced vibration SYNERGETICS vibration control 

分 类 号：P751[交通运输工程—港口、海岸及近海工程]