蒸汽发生器内二次侧水位对倒U型管内倒流特性的影响分析

在自然循环条件下,蒸汽发生器(SG)倒U型管内的流体流动会不稳定,可造成一部分倒U型管内流体处于倒流状态。基于Boussinesq假设,建立了与SG二次侧水位有关的倒U型管内流体一维守恒控制方程,采用线性微扰理论分析SG二次侧水位对倒U型管内倒流特性的影响,并采用RELAP5/MOD3.2程序进行了数值模拟。结果表明:在一定倒U型管进口条件下,SG二次侧水位的降低使倒U型管内流动的特征压降增大,特征流量减少,稳定性参数增加,相对于正常水位时更易不稳定,倒流更易发生,长管较短管更易发生倒流。

Effect of Water Level of Steam Generator Secondary Sideon Reversed Flow of Inverted U-tube

For natural circulation, it is shown that the flow in inverted U-tubes is unsteady, and the water in some inverted U-tubes flows backward.Based on the assumption of Boussinesq, one-dimensional governing equations about the water level of steam generator secondary side were established.The effects of water level of steam generator secondary side on the flow instability were analyzed by using the linear perturbation theory, and the RELAP5/MOD3.2 code was used to simulate the phenomena.The results show that as the inlet condition of inverted U-tube is unchanged, the characteristic pressure drop of flow in inverted U-tube increases and the characteristic mass flow rate decreases with the decrease of water level of steam generator secondary side, meanwhile, the stability parameters of inverted U-tube increase, so the water flows backward in inverted U-tube which will occur more easily with the decrease of water level of steam generator secondary side, and it is easier for the longer U-tube to flow backward.