基于流固耦合界面数据传递模型的水电站厂房流激振动分析

Flow-induced Vibration Analysis of Hydropower House Based on Data Transfer Model for Fluid-structure Coupling Interface

在现有大中型水电站机组普遍存在水力振动的情况下,如何建立一套完善的水力-厂房耦合振动模型,特别是适用于大型复杂工程计算的流固耦合界面数据传递模型,并以此进行水电站厂房流激振动的预测,是厂房振动方面亟待研究的课题。本文探讨了国内外常用的几种流固耦合数据传递插值算法的优劣,将近年来在航空、地形学、医学等领域广泛应用的C2紧支径向基函数插值方法进行了优化与改进,改善了该插值方法存在的精度和效率之间的平衡问题,并基于此建立厂房流固耦合数据传递模型,进行水电站厂房流激振动分析。分析结果表明,当流体网格数远大于结构网格数时(5倍以上),局部插值法的最大误差控制在工程应用可接受范围内,在网格量巨大的相关工程计算中可以考虑使用局部插值法以节省时间成本;改进后的C2紧支径向基函数可以进一步减小误差,提高精度,在大型复杂耦合界面数据传递中具有很大的优势;流道中压力脉动以叶片通过频率为主,水轮机叶片与导叶间静动干扰所引起的流体脉动压力对厂房整体结构振动影响较为明显。

Hydraulic vibrations generally exist in large units of hydropower stations. How to predict the hydraulic vibration before a hydropower station goes into operation is a significant research subject. Establishing a fluid-solid coupling mathematical model is an important step. This work focused on interpolation methods used for fluid-solid coupling problems of hydropower stations. Advantages and disadvantages of typical interpolation methods in the world were discussed. The C2 compactly supported radial basis function was improved and optimized to develop a data transfer model for fluid-structure coupling interface. Turbine unsteady fluid grid and structural dynamics calculation grid were built. And a vibration analysis of hydropower plant was conducted. When the number of fluid mesh was much larger than the number of structural mesh,local interpolations were available to save time cost in construction project with large amount of grids. Errors were further reduced by improving C2 compactly supported radial basis function which was better for data transferring in large and complex coupling interface. Blade passing frequency was the main frequency of fluid in Hydraulic turbine runner. Pressure fluctuations caused by static and dynamic disturbance had significant impact on structural vibrations in hydropower station plant.