基于流固耦合效应的梯级泵站输水管道振动特性分析

摘要

为解决管道结构固有振动特性分析中选取高精度流固耦合模型的方法问题,以景电工程中梯级泵站输水管道为研究对象,运用附加质量法和直接耦合法原理,建立不同的流固耦合模型,对其进行固有模态特征提取,并将求解结果与SSI法模态辨识结果对比.结果表明:直接耦合法模型的结果与SSI法辨识结果吻合得较好,最大误差为3.62％,同阶次的计算精度均优于附加质量模型,频率间隔小,弥补了附加质量模型出现的模态缺失现象;直接耦合模型的计算结果在模拟阶数和精度方面都优于附加质量模型,能较好地反映管道结构的固有振动特性,可在复杂管系结构的动力特性分析中应用.%As the basic carrier of long-distance inter-basin water conveyance project of pressure piping,pressure piping is an important part of agricultural engineering and water conservancy projects,which plays an important role in solving the uneven space-time distribution of water resources.The vibration during the operation is the critical problem in the design and safety evaluation of water pipeline.In order to solve the problem of how to improve the precision of the FSI (fluid-solid interaction) model in the natural vibration characteristics analysis of the piping,two different FSI models of a piping in cascade pumping station of Jingdian Project were built,by using the additional mass method and direct coupling method respectively.Then the modal characteristics of two FSI models which were obtained in the natural vibration characteristics analysis were compared with the modal characteristics of the prototype piping identified by stochastic subspace identification (SSI) method.The comparison results show that the simulation results of the model by using direct coupling method were in good agreement with the results identified by SSI method,and the maximum error was 3.62％.In the comparison of calculation accuracy of the same order,the model by using direct coupling method outperforms the model by using additional mass method,making up for the lack of the modes that the additional mass model can not work out.The results show that FSI affects the piping system modal frequency seriously and the model by using direct coupling method is superior to the additional mass model in terms of the order number and precision of the simulation,reflecting the real natural vibration characteristics of liquid conveying piping.This method can be used in the analysis of the dynamic characteristics of complicated pipe systems.