摘要
内波的波致流为沿水深方向非均匀分布的剪切流,而深海平台立管的自然模态具有低频、密集的特性,这种流场和结构的特点使得深水立管的涡激振动表现出高阶模态、多阶模态参与振动的特点。该文研究了大长径比立管在内波流场作用下的锁频特性,建立了基于模态能量理论的多模态锁频的计算方法,并应用于改进的尾流振子模型进行立管涡激振动响应预测。结合实例,进行了深海平台立管的涡激振动响应分析,比较了内波、海流等不同流场作用下立管的涡激振动响应;分析了波致流速对响应位移和应力的影响,结果表明随着波致流速的增大,响应的RMS振幅和应力有不同程度的增大;需要注意高应力响应伴随高频率振动对结构疲劳寿命的影响。
The internal-wave-induced horizontal flow velocity distributes un-uniformly along the riser axis and is usually regarded as shear flow.The natural frequency of deepwater riser is low and crowded due to the high aspect ratio.Therefore,the prediction of the vortex-induce vibration（VIV） of deepwater riser suffered from multi-modes and higher-mode becomes more difficult.An approach based on modal energy is developed and subsequently is applied to the modified wake-oscillator model to predict VIV.At last,illustrative examples are given in which the VIV of flexible riser in the internal-wave-induced fluid field are calculated and compared with VIV in the sea current.The effects of internal-wave-induced flow velocity on VIV are explored.Our results show that both displacement and stress responses become larger with the increase of induced flow velocity;especially higher stress response companied with higher frequency vibration may significantly affect the fatigue life of structures.
出处
《工程力学》
EI
CSCD
北大核心
2011年第12期250-256,共7页
Engineering Mechanics
基金
中科院方向性项目(KJCX2-YW-L07)
中央高校基本科研业务费专项资金项目(YWF-10-01-B05)
关键词
涡激振动
多模态
内波
剪切流
尾流振子
vortex-induced vibration
mode
internal wave
shear flow
wake-oscillator
