摇摆条件下典型通道过冷沸腾核热耦合研究

发布时间：2018-10-18 09:55

【摘要】：海洋核电站作为核能发展的一个新方向,成为目前研究的热点。本文以海洋核电站堆芯组件的中心子通道在过冷沸腾工况下,受到摇摆运动为背景,通过数值模拟方法,进行了摇摆运动下过冷沸腾及核热耦合特性的数值模拟研究及理论分析。本文基于三维计算流体力学(CFD)软件Fluent,通过用户自定义函数(UDF)接口,将摇摆及相间传输模型通过源项的方式添加到各控制方程并耦合核反馈模块,建立了用于模拟摇摆条件下过冷沸腾及核热耦合的程序。通过对该程序的各个模块进行独立模拟校验,验证了该方法的正确性。通过对摇摆条件下的过冷沸腾进行数值模拟,发现在反应堆运行条件下,相对较低空泡份额工况下更容易受到摇摆运动的影响,造成空泡份额的波动。通过对压降的分析发现,摇摆会引起压降的波动,但压降的波动幅度不受摇摆周期和摇摆角度的影响。不同的摇摆周期和摇摆角度,对轴向的空泡份额变化和汽泡的径向相对运动影响不同,摇摆周期越小、摇摆角度越大不但使轴向空泡份额越大,还会使径向的汽泡相对运动速度越大,分析还发现汽泡脱离点附近区域对摇摆运动最为敏感。稳态下的过冷沸腾核热耦合计算,为摇摆条件下的过冷沸腾核热耦合模拟提供了初始条件,得到的实际功率分布呈现出随着高度的增加而减小的趋势。与均匀热流密度分布下的轴向空泡份额变化相比,实际功率分布下的轴向空泡份额变化受摇摆运动的影响更大;在考虑核反馈后,轴向的空泡份额波动受到明显的抑制,保证了运行的稳定和安全。对系统功率进行分析发现,摇摆运动使整体空泡份额增大,由于系统的负反应性,核反馈效应会降低系统整体功率;但是由于轴向各段的空泡份额波动情况不同,轴向各段的功率波动呈不同的变化规律。
[Abstract]:As a new direction of nuclear energy development, marine nuclear power plant has become a hot spot in current research. In this paper, under the condition of subcooled boiling, the central sub-channel of the core assembly of the marine nuclear power plant is subjected to rocking motion, and the numerical simulation method is used. Numerical simulation and theoretical analysis of the characteristics of subcooled boiling and nuclear heat coupling under rocking motion were carried out. In this paper, based on 3D computational fluid dynamics (CFD) software Fluent, through user defined function (UDF) interface, the swinging and interphase transmission models are added to each control equation by source term and coupled with kernel feedback module. A program for simulating subcooled boiling and nuclear heat coupling under rocking conditions has been established. The correctness of the method is verified by independent simulation of each module of the program. By numerical simulation of subcooled boiling under rocking condition, it is found that under the condition of reactor operation, it is easier to be affected by rocking motion than under the condition of lower void fraction, resulting in the fluctuation of cavitation share. Through the analysis of the pressure drop, it is found that the swing will cause the fluctuation of the pressure drop, but the fluctuation amplitude of the pressure drop is not affected by the rocking period and the rocking angle. Different rocking periods and angles have different effects on the axial cavitation fraction and the radial relative motion of the bubble. The smaller the rocking period is, the larger the rocking angle is, and the larger the axial cavitation fraction is, It is also found that the relative velocity of the radial bubble is higher, and the region near the breakaway point is the most sensitive to the rocking motion. The calculation of subcooled boiling nucleus-heat coupling under steady state provides the initial conditions for the simulation of subcooled boiling nuclei and heat coupling under rocking conditions. The actual power distribution shows a decreasing trend with the increase of height. Compared with the change of axial cavitation share under uniform heat flux distribution, the axial cavitation share change under real power distribution is more affected by the rocking motion, and the fluctuation of axial cavitation share is obviously restrained after considering nuclear feedback. It ensures the stability and safety of the operation. By analyzing the system power, it is found that the motion of swinging makes the whole cavitation share increase, because of the negative reactivity of the system, the nuclear feedback effect will reduce the overall power of the system, but the fluctuation of the axial void share is different. The variation of axial power fluctuation is different.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TK124;TM623

【参考文献】