甲烷、水蒸气与正壬烷气体的三相凝结流动数值分析

Numerical Analysis on the Three-Phase Flow With Condensation of CH_4,H_2O and n-C_9H_(20)

对甲烷(CH4)、水蒸气(H2O)和正壬烷(n-C9H20)组成的混合气体建立了三相凝结流动数值模型,利用该模型对拉阀尔喷管内甲烷气体中含饱和水蒸气和饱和正壬烷气体的凝结流动进行了数值分析。结果表明,由于物性的差异,该三相流动中正壬烷气体开始凝结的位置比水蒸气开始凝结的位置滞后约0.05 m;随着喷管进口压力的提高,水蒸气与正壬烷气体成核时对应的过冷度、成核率、液滴数、凝结出的液相质量分数等参数均减小。在该三相凝结流动中,水蒸气和正壬烷气体凝结过程中放出的热量对二者过冷度分布相互造成影响,从而使两种可凝气体的凝结强度降低。

A numerical model was developed to simulate the three--phase flow with condensation of the mixture of methane （CH4）, water vapor （H2O） and nonane （n-C9 H20）. Using this model the condensing flow of methane with saturated water vapor and nonane vapor in a convergent--divergent nozzle were investigated. The result shows that in this three--phase flow, the nucleation position of nonane vapor is 0.05 m downstream of that of water vapor, which is a result of the different thermo --physical properties of H2O and n- C9 H20. With the inlet pressure rises, the supercooling leading to nucleation, the nucleation rate, the number of liquid droplets and the mass fraction of liquid phase decrease for both water vapor and nonane vapor. The result also indicates that in the three--phase flow, the latent heat released during the condensation processes of water vapor and nonane vapor changes each other＇s supercooling. As a result the condensation processes of water vapor and nonane vapor are weakened.