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采用一种基于Eulerian/Eulerian分别描述汽液两相的数值模型,对缩放喷管内的湿蒸汽自激振荡凝结流动进行了数值模拟,并分析了该现象的机理.从空气动力学的角度介绍了稳态和非稳态流动之间的转换过程;从分析各类振荡模式的形成机理出发,结合气动激波的运动规律,解释了在保持喷管进口总压不变的情况下,自激振荡频率随进口过冷度的增大先降低后升高的特性;分析了二次凝结的成因及其激波运动规律,发现位于喷管收缩段的凝结同样能引发自激振荡现象.
A numerical model based on the Eulerian / Eulerian description of the vapor-liquid two-phase system is proposed to simulate the self-oscillating and condensing flow of the wet steam in the scaled nozzle. The mechanism of this phenomenon is analyzed. From the aerodynamic point of view, Based on the analysis of the formation mechanism of various types of oscillation modes and the movement law of the pneumatic shock waves, it is explained that under the condition of keeping the total pressure of the nozzle intact, self-excited oscillation The frequency decreases with the increase of inlet undercooling and then increases. The causes of secondary condensation and the shock wave motion are analyzed. It is found that the condensation in the contraction section of the nozzle also induces self-oscillation.