Abstract With the increase demand for energy for ocean development, small reactors with natural circulation as the normal operating conditions are increasingly becoming an important energy supply option. The complex marine environment, such as fluctuations in the flow rate of coolant in nuclear reactor due to wind and waves, affects the flow resistance and heat transfer characteristic of the coolant, threatening the safety of the reactor. The current study performs one-dimensional and three-dimensional code coupling method to analyze the effect on flow resistance and heat transfer in a narrow rectangular channel under rolling condition. In addition to the influence of flow pulsation which has been considered universally by past studies, it was found that transverse mixed convection caused by external force fields, and boundary layer acceleration caused by the ununiform distribution of cross-section pressure, also have an impact on flow resistance and heat transfer. Unlike the flow pulsation, which has no effect on the time-average flow resistance and heat transfer, the transverse mixed convection increases the time-average flow resistance while also enhances the time-averaged heat transfer. Boundary layer acceleration occurs at lower Reynold number (Re≈800), and results in a steep increase in flow resistance, while the effect on heat transfer is not so significant. The relative strength of the three effects is impacted by the rolling parameters maximum rolling angle θ0 and period t0. The flow pulsation effect increases with increasing θ0 and decreasing period, while the mixed convection effect increases with increasing θ0.

中文翻译：

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自然循环下窄矩形通道滚动运动对流阻和传热的影响

摘要 随着海洋开发对能源需求的增加，以自然循环为正常运行条件的小型反应堆日益成为重要的能源供应选择。复杂的海洋环境，如风浪引起核反应堆内冷却剂流量的波动，影响了冷却剂的流动阻力和传热特性，威胁到反应堆的安全。目前的研究采用一维和三维代码耦合的方法来分析轧制条件下窄矩形通道内流动阻力和传热的影响。除了以往研究普遍认为的流动脉动的影响外，还发现外力场引起的横向混合对流，截面压力分布不均引起的边界层加速度和边界层加速度，也对流动阻力和传热产生影响。与流动脉动对时均流阻和传热没有影响不同，横向混合对流在增加时均流阻的同时也增强了时均传热。边界层加速发生在较低雷诺数 (Re≈800) 时，导致流动阻力急剧增加，而对传热的影响不大。三种效应的相对强度受滚动参数最大滚动角θ0和周期t0的影响。流动脉动效应随着θ0的增加和周期的减少而增加，而混合对流效应随着θ0的增加而增加。