反应堆堆内构件流体激振力的数值模型研究

Numerical Model of Fluid Induced Vibration Force of Reactor Internals

针对反应堆堆内构件流致振动分析评价中如何合理获取流体激振力的关键技术难题,开展了典型反应堆堆内构件三维流场分析的数值模型研究。研究基于计算流体动力学方法,首先,根据反应堆堆内构件的结构特点和运行工况参数,将实际结构的关键部件、物理边界提取并做适当简化,在合理降低计算规模的同时,又充分保留其流场特征;其次,综合考虑计算资源和计算效率,采用结构网格和非结构网格相结合的混合网格划分方式以及分区化的网格尺寸策略,将流场十分复杂但并不关注其细节的堆芯段采用多孔介质模拟,使划分的网格能够捕捉流场特征,进而建立了适用于工程的三维流场分析模型,并对预测结果较好的3种湍流模型进行了对比研究。获得了反应堆堆内构件的三维流线和压力分布特征、典型测点压力脉动的时程与功率谱密度(PSD)特性、3种湍流模型对反应堆堆内构件流体激振力的预测情况、作用于吊篮表面的流体激振力特性。结果表明,大涡模拟(LES)模型可以较好地预测反应堆堆内构件的流体激振力,同时又具有一定的保守性,作用在反应堆堆内构件的流体激振力符合宽带随机性,可为反应堆堆内构件流致振动分析评价提供关键参数和输入载荷。

Aiming at difficulty in obtaining fluid exciting force in the flow induced vibration analysis and evaluation of reactor internals,the numerical model of three-dimensional flow field analysis of typical reactor internals is studied based on computational fluid dynamics(CFD).Firstly,according to the structural characteristics and operating parameters of reactor internals,the key components and physical boundaries of the actual structure are extracted and simplified,so as to reduce the calculation scale reasonably and retain the flow field characteristics.Secondly,considering the computational resources and efficiency,the hybrid grid generation method of structural grid and unstructured grid and the partition grid size strategy are adopted.In order to capture the characteristics of the flow field,porous media is used to simulate the core section with complex flow field but not paying attention to its details,and then a three-dimensional flow field analysis model suitable for engineering is established.Three turbulence models with good prediction results are compared.The three-dimensional streamline and pressure distribution characteristics of reactor internals,the time history and PSD characteristics of pressure fluctuation at typical monitoring points,the prediction of fluid excitation forces of reactor internals by three turbulence models,and the characteristics of fluid exciting force acting on the surface of the core barrel are obtained.The results show that LES model can predict the fluid induced vibration forces of reactor internals,and has a certain conservatism.The fluid induced vibration forces acting on reactor internals conform to the wide-band and randomness.It can provide key parameters and input loads for flow induced vibration analysis and evaluation of reactor internals.