AP1000核电机组一回路稳压器波入过程瞬态特性研究

Research on Transient Wave Entry Characteristics of the Primary Loop Pressurizer in an AP1000 Nuclear Power Unit

为研究AP1000核电机组稳压器内波入流的演化过程和水力特性,采用三维非稳态传热的计算流体动力学(CFD)方法捕捉波入过程中冷热流体混合的温度、速度波动强度,将密度处理为温度的多项式函数来估算浮升力的影响。结果表明:模拟值与试验值吻合良好,RSM湍流模型结合VOF多相流传热模型能够有效地对波入过程的发展趋势进行预测;理查森数Ri对冷热流体的混合有重要影响,其大小决定浮升力对流体的影响;冷热流体的掺混主要发生在下封头-0.5m<z<0.5 m区域内;温度、速度波动最剧烈的地方集中在-0.3m<z<0.3 m,其波动峰值随着波入过程的推进逐渐变大,电加热器应尽量避免布置在该区域内,以改善其恶劣的工作环境。

To study the evolution process and hydraulic characteristics of the wave entry flow in an AP1000 pressurizer,a three-dimensional CFD method was used to analyze the unsteady heat transfer to capture the intensity of temperature and velocity fluctuation for the mixture of cold and hot fluids in the wave entry process,while the effect of buoyancy was estimated by taking the fluid density as a polynomial function of temperature.Results show that the simulated values agree well with the experimental data,and the RSM turbulence model combined with VOF multiphase heat transfer model can effectively predict the development trend of wave entry process.The Richardson number Ri has an important influence on the mixing of hot and cold fluids,and its magnitude determines the influence of buoyancy on fluids.The mixing of hot and cold fluids mainly occurs in the-0.5 m<z<0.5 m area of the lower head;the most intense fluctuations of temperature and velocity are concentrated in the area of-0.3 m<z<0.3 m,and the peak value of fluctuation increases gradually with the advance of wave entry process,so the electric heater should avoid to be placed in such rugged environment.