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中文核心期刊

铅铋快堆绕丝燃料棒非线性流致振动及微动磨蚀特性研究

NONLINEAR FLOW INDUCED VIBRATION AND FRETTING WEAR CHARACTERISTICS OF WIRE-WRAPPED FUEL ROD IN LEAD-BISMUTH FAST REACTOR

  • 摘要: 铅铋快堆是第四代反应堆的重要堆型, 采用液态铅铋作为传热工质, 具备固有安全性高、易于模块化等优势. 绕丝燃料棒作为其核心部件, 在铅铋冲刷下可能发生流致振动, 进而引起包壳微动磨蚀甚至破损. 为掌握关键参数对振动响应和微动磨蚀结果的影响, 并实现对包壳微动磨蚀寿命的预测, 首先建立了绕丝燃料棒非线性流致振动理论模型, 综合考虑了湍流激励、绕丝与相邻棒碰撞摩擦及非线性流体弹性力. 随后, 开展了铅铋环境下绕丝燃料棒流致振动实验, 获取了典型流速下的应变响应, 验证了理论模型的适用性. 基于模型, 得到了振动位移、应变、接触力及最大磨蚀深度率随无量纲流速的变化规律. 结果表明, 振动位移和应变均与无量纲流速正相关, 其概率密度符合Weibull分布; 在0.2无量纲流速下, 最大无量纲碰撞力与摩擦力均方根值分别为0.37和0.039; 包壳最大磨蚀深度率与无量纲流速近似呈对数正相关, 在0.2无量纲流速下可达16.5 μm/年. 本文发展的理论模型为定量分析流致振动响应与微动磨蚀提供了有效手段, 也为铅铋快堆燃料组件的力学设计与评估奠定了基础.

     

    Abstract: The lead-bismuth fast reactor is one of the important types in the fourth-generation reactors. It uses liquid lead-bismuth as the heat transfer medium, which has advantages such as inherent safety and ease of modularization. The wire-wrapped fuel rod is the core component in the lead-bismuth fast reactor, and exhibits complex flow induced vibration phenomena under the excitation of lead-bismuth, which can lead to fretting wear and damage of cladding. To quantitatively analyze the flow induced vibration and fretting wear of wire-wrapped fuel rod, understand the influences of typical parameters on the results of vibration response and fretting wear, and estimate the lifetime of cladding. Firstly, a nonlinear flow induced vibration theoretical model was established, considering the turbulent excitation, contact between wire and adjacent rod, and the nonlinear fluid-elastic force. Then, the flow induced vibration experiment of wire-wrapped fuel rod in lead-bismuth medium was conducted to obtain the strain results of structure under typical flow velocity. The experimental results proved the applicability of the theoretical model. Finally, the law of vibration displacement, strain, contact force and the maximal wear depth rate with the dimensionless flow velocity were obtained. The results show that the displacement and strain of the wire-wrapped fuel rod are positively correlated with the dimensionless flow velocity, and their probability density conforms to the Weibull distribution. For dimensionless flow velocity 0.2, the maximal dimensionless impact force and friction force root mean square values are 0.37 and 0.039, respectively. The maximal wear depth rate of cladding is logarithmically positively correlated with the dimensionless flow velocity, when dimensionless flow velocity equals to 0.2, the maximal wear depth rate can be 16.5 μm/year. The developed theoretical model for the nonlinear flow induced vibration of wire-wrapped fuel rod provides an effective tool for quantitatively conducting vibration response and fretting wear analysis, also a basis for the mechanical design and evaluation of lead-bismuth fast reactor fuel assembly.

     

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