乏燃料剪切机气固两相流分析及结构优化

后处理厂普遍采用机械法的剪切机系统进行乏燃料破解，剪切产生的放射性粉尘需进行包容设计，确保乏燃料芯块的充分利用和热室的可维修性，研究乏燃料剪切机内气流形态和颗粒物分布运动规律对于保障剪切机的正常运行具有重要意义。为补充试验研究和理论研究的不足，改善剪切机内粉尘分布、降低粉尘水平和优化剪切机设计，本文以注入模拟颗粒的乏燃料剪切机为研究对象、离散颗粒模型为基础，对剪切机内气固两相流进行了计算流体力学模拟。通过分析剪切机内流体的速度、压力和湍动能的分布规律，以及粉尘颗粒对箱体内部的破坏作用，对剪切机的结构和边界条件设计进行了优化。结果表明：改进流道结构和输入条件可有效避免剪切机内涡流、湍流和高冲击力的产生，箱体内气固两相流的速度场、压力场和湍动能分布规律较为均匀，梯度变化较小，可有效降低箱壁损伤。

Gas-solid Two-phase Flow Analysis and Structure Optimizationof Spent Fuel Shearing Machine

Mechanical shearing systems are commonly used in reprocessing plants to crack spent fuel. The radioactive dust generated by shearing needs to be contained to ensure the full utilization of spent fuel pellets and the maintainability of the hot chamber. The airflow pattern and particle distribution and movement in the machine are of great significance to ensure the normal operation of the shearing machine. In order to supplement the deficiencies of experimental research and theoretical research, and improve dust distribution, reduce dust levels and optimize design of the shearing machine, the flow field in bar shearing machine with injected virtual particles was simulated based on the discrete particle model. By analyzing the distribution of velocity, pressure and turbulent kinetic energy of the fluid in shearing machine and the destructive effect of dust particles on the inner wall of shearing machine, the structure and boundary conditions of the shear were optimized. The results show that the eddy current, turbulence and high impact force can be effectively avoided by improving the structure of the flow passage and the input conditions. The velocity field, pressure field and turbulent kinetic energy distribution of gas-solid two-phase flow in the box are more uniform and the gradient change is smaller, and the damage of box wall is effectively reduced.