Flow and heat transfer in fuel rod bundles of water-cooled reactors with modified cell-type spacer grids
Flow and heat transfer in fuel rod bundles of water-cooled reactors with modified cell-type spacer grids
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DOI：
10.1016/j.nucet.2016.01.009
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发表时间：
2015-10
影响因子：
--
通讯作者：
V. G. Krapivtsev;P. Markov;V. Solonin
中科院分区：
文献类型：
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作者：
V. G. Krapivtsev;P. Markov;V. Solonin
本文研究了采用改进型格栅冷却反应堆燃料棒束的冷却液流动和换热问题。间隔格栅是由Elektrostal的JSC Mashinostroitelny Zavod开发的，与标准格栅的不同之处在于接触燃料包壳外表面的波纹的倾斜度。这种槽内的冷却剂流动导致流动内部形成的速度矢量的切向分量，其取向与波纹倾斜方向一致。通过在网格阵列内布置几何上不同或相同的单元，可以在网格下游的棒束中产生不同的二次流。本文考虑了产生两种二次冷却剂流动的隔板格栅：燃料棒周围和棒排之间。研究基于计算流体力学方法，计算结果与气动试验数据进行了验证。对网格下游二次流的形成机理进行了描述，并对其强度进行了定量估算。给出了弱压缩等温气流条件下和VVER-1000反应堆主冷却剂参数下不同雷诺数下网格流动阻力系数的数据。在不同边界条件下，用热尾迹方法分析了隔栅下游冷却剂混合的强化过程。结果表明，由于产生了定向对流输运，改进的格子格栅可以用于并有效地平坦冷却剂流动中的温度不均匀。
The paper considers the flow and heat transfer in coolant flows cooling the fuel rod bundles of nuclear reactors with modified cell-type spacer grids. The spacer grids were developed by JSC Mashinostroitelny Zavod, Elektrostal, and differ from standard grids in the inclination of the corrugations that contact the fuel cladding outer surface. The coolant flow inside such cells leads to tangential components of the velocity vector formed inside the flow with an orientation in accordance with the corrugation inclination direction. By arranging geometrically different or identical cells within the grid array, it is possible to generate different secondary flows in the rod bundles downstream of the grid. The paper considers spacer grids that generate two types of secondary coolant flows: around the fuel rods and between the rod rows. The investigation was based on computational fluid dynamics methods with the calculation results validated against aerodynamic test data. Mechanisms of the secondary flow formation downstream of the grids have been described, and the intensities thereof have been quantitatively estimated. Data is presented on the grid flow resistance coefficients at different Reynolds numbers both in conditions of a weakly compressed isothermal air flow and with parameters representative of the VVER-1000 reactor primary coolants. Intensification of the coolant mixing downstream of the spacer grids was analyzed by a thermal wake method for different boundary conditions. A conclusion has been made that the modified cell-type spacer grids can be used for and are efficient in flattening temperature non-uniformities in the coolant flow due to creating a directed convective transport.