压水堆燃料棒湍流激励流致振动响应计算方法研究

Study on Calculation Method of Flow-induced Vibration Response of Turbulent Excitation in Pressurized Water Reactor Fuel Rod

当湍流流过燃料棒表面时,湍流速度分量产生表面随机压力脉动。采用随机振动响应的模态分析技术,得出圆柱体横向振动位移的均方值一般表达形式。根据压水堆燃料棒的结构和流场分布特征,将作用在燃料棒上的流体力等效为脉动随机载荷,引入湍流功率谱密度函数,结合相关功率谱密度试验参数,推导每阶模态的振动位移均方值。分别讨论轴向和横向流引起的各阶模态的振动幅值,并给出各阶模态的对数衰减阻尼,轴向和横向流引起的振动幅值采用线性组合方法,对各阶模态的采用10%的模态组合方法得到所有模态的燃料棒振动幅值,给出了完整的燃料棒轴向和横向湍流激励振动总幅值的通用计算方法和分析流程。

When turbulent flow comes into contact with the surface of fuel rod,in addition to the forces produced by the mean flow component,random surface pressure fluctuations are produced by the turbulent velocity component.Based on random vibration theory,the mode shape method is used to derive the general formula of quadratic mean of the transverse vibrational displacement.According to the structure and distribution of flow field of pressurized water reactor fuel rod,the fluid force along the rod is treated as a fluctuant random load,power spectrum density function and some parameters obtained from experiment are introduced,quadratic mean of the transverse vibrational displacement for each mode is derived from the general formula.Due to fuel rod is subjected to action of axial and transverse flow at the same time,the RMS vibration amplitude for each mode is separately discussed.The logarithmic damping is calculated by semi-empirical formula.The axial and cross flow contributions are combined linearly,10%frequency grouping method is proposed to do modal combination.The general calculation method and analysis process of the total amplitude of axial and transverse turbulence excited vibration of fuel rod are presented.