AP1000核主泵排气过渡工况下瞬态流动特性研究

Study on Transient Flow Characteristics of AP1000 Nuclear Reactor Coolant Pump under Exhaust Transit Condition

为了研究核主泵在排气过渡工况下的气液两相流瞬态流动特性,基于非均相流模型,采用CFX软件对核主泵排气过渡工况进行瞬态数值模拟,通过分析叶轮、导叶流道内的压力脉动、涡量变化及速度分布,得到了排气过渡过程的流动变化规律。研究结果表明:气液两相工况下,叶轮各流道内气相、液相的不均匀分布及两相之间的滑移作用,导致叶轮径向力产生大幅度波动;核主泵采用的扭曲型径向导叶,在进口含气率较高的工况下,其流道内易产生气泡堆积现象,使过流面积减小,产生较大的能量损失;核主泵类球形蜗壳的对称性结构,使左侧类隔舌部位出现低流速区,堵塞了部分出口流道,这也是核主泵排气过渡工况运行不稳定的重要原因。

In order to study the gas-liquid two-phase transient flow characteristics of the nuclear reactor coolant pump under the exhaust transit condition,the transit process of exhaust of nuclear reactor coolant pump was simulated by using CFX software and the heterogeneous turbulence flow model.By analyzing the pressure pulsations,vorticity and velocity distribution in the impeller and vanes flow channel,the flow variation law of exhaust transit process was obtained.The results show that the radial force of the impeller generates large fluctuations under gas-liquid two-phase flow condition,caused by the gas phase and liquid phase unevenly distributed in each channel of the impeller,and the slip effect between the two phases.It is easy to generate bubbles accumulatingphenomenon within the channels of the twisted radial guide vanes on high inlet gas flow rate conditions.The phenomenon makes the flow area reduced,resulting in greater energy loss.The spherical symmetry structure of the nuclear reactor coolant pump volute makes the left side of the separation tongue appear low velocity area,plugging part of the outlet flow channel.It is also an important reason for the unstable operation during the process of the exhaust.