轴向非均匀加热对并联通道流动不稳定性的影响

基于均相流模型建立并联通道系统的控制方程，采用交错网格技术和半隐式差分离散控制方程，并使用追赶法求解来模拟并联通道的两相流动特征。采用轴向余弦功率加热模拟轴向非均匀功率加热。运用小扰动法，获得了不同压力、入口过冷度和轴向功率加热方式下的稳定性边界（MSB）和三维不稳定性空间。对于余弦和均匀功率加热，系统稳定性均随系统压力的增大而增强。余弦功率加热在高过冷度区降低并联通道系统稳定性，而在低过冷度区增强系统稳定性。随进口阻力系数的增加，处于余弦功率加热的并联通道系统稳定性增强，MSB的拐点逐渐向高过冷度区移动。

Analysis of Flow Instability in Parallel Channels Under Axial Non-uniform Heating Condition

Based on the homogeneous flow model, the system control equations of parallel channels were established. Semi-implicit finite-difference method with staggered mesh was used to discretize the system control equations solved with a chasing method to simulate the two-phase flow behavior of parallel channels. The cosine heat flux was selected to simulate the axial non-uniform heating. The marginal stability boundary (MSB) and three-dimensional instability space under different system pressures, different inlet subcoolings and different axial heating modes were obtained by using small perturbation method. The stability of parallel channels increases with system pressures for both cosine and uniform heat flux. At high inlet subcooling region, the cosine heat flux can strengthen the system stability. However, at low inlet subcooling region, the negative effect on the system stability will be caused by cosine heat flux. For the cosine heat flux, the increase of inlet resistant coefficient will move the turning point of the MSB to high inlet subcooling number and enhance the system stability.