深海取水管在内外流作用下的动力性能

Dynamic Characteristics of Deep-Sea Intake Pipe under Internal and External Flow

深海取水管道是一种大长细比、高内流流速的悬垂吸液管道,模拟取水管的真实工作状态,研究在内外流作用下的管道动力性能十分必要。基于小尺度模型试验,研究内外流对管道的动力特性影响。结果表明:大部分工况下,内外流共同作用引起的管道振动幅度和频率主要受外流影响;内外流共同作用下,内流流速增加会导致位移振动主频略微降低,顶部张力增加,管道应变响应减小,但其对振动的应变主导阶数影响较小;管道顶部连接方式、底部配重、浸没水深都会影响管道在内外流作用下的涡激振动特性,即顶部铰接相较于固定连接更容易激发管道涡激振动横流向的高阶模态振动,底部配重在小外流流速下会使管道振动幅值降低,在大外流流速下会使管道振动幅值增大,激发横流向高阶主导频率跃迁,浸没水深增加会使管道振动主导频率降低。研究成果可为实际工程项目中深海取水管的设计提供参考依据。

The deep-sea intake pipe is a type of overhanging suction pipe with a high slenderness ratio and high internal flow velocity.Simulating the real operating conditions of the intake pipe and studying the pipe's dynamic performance under the influence of internal and external flows is extremely necessary.Based on small-scale model tests,the influence of internal and external flows on the dynamic characteristics of pipes is investigated.The results show that under most working conditions,the amplitude and frequency of pipe vibration caused by the combined action of internal and external flow are mainly affected by the outflow.Under the combined action of internal and external flow,the increase of internal flow velocity will lead to a slight decrease in the main frequency of displacement vibration,an increase in the top tension,and a decrease in the strain response of the pipe.But it has little influence on the strain dominant order of vibration.The top connection mode,bottom counterweight,and immersion depth of the pipe will affect the vortex-induced vibration characteristics of the pipe under the action of internal and external flow.That is,the top hinge is more likely to stimulate the high-order modal vibration of the vortex-induced transverse flow direction of the pipe than the fixed connection.And the bottom counterweight will reduce the vibration amplitude of the pipe under the small outflow velocity,and increase the vibration amplitude of the pipe under the large outflow velocity,and stimulate the transition of the cross-flow to the higher-order dominant frequency.Meantime the increase of the submerged water depth will reduce the dominant frequency of the pipe vibration.The research results can provide a reference for the design of deep-sea intake pipes in practical engineering projects.