喷管内水蒸气凝结相变的数值模拟研究

Numerical Study on the Condensation Phase Transformation of Water Vapor in Supersonic Nozzle

引入水蒸气真实气体物性,考虑相变、速度滑移等影响因素,建立了超音速水蒸气非平衡凝结流动数值模型,通过与实验数据对比,验证了模型的正确性。随后对喷管内水蒸气超音速流动进行了数值模拟研究,清晰的捕捉到了"X型"凝结激波,并对其形态形成原因进行了分析。通过与理想蒸汽模拟对比,结果表明:水蒸气的非平衡凝结会形成凝结激波现象,导致流场中压力和温度突然升高,速度骤然降低;随后对非平衡凝结现象发生后,液滴半径、液滴数和湿度的增长趋势进行了计算分析。发现在喉部下游0.1 m处,液滴数由0突跃至1014数量级,表明水蒸气发生非平衡凝结,极短时间内产生了大量凝结核,液滴半径和湿度也在短时间内迅速增加。

With the real thermodynamic properties of water vapor and the consideration of the effects of the phase transformation and velocity slip,a numerical model for the non-equilibrium supersonic water vapor condensation flow was established. This numerical model was first verified by the comparison with the experimental data. Then it was used to simulate the vapor flow in a supersonic nozzle. The 'X-type'condensation shock was clearly captured,and its morphology and formation causes were analyzed. In comparison with the simulation with ideal vapor,it shows that the non-equilibrium steam condensation forms condensation shock,leading to the sudden increase in flow field pressure and temperature,and in turn,abrupt decrease in flow velocity. The droplet radius,droplet number,growth trends and humidity after non-equilibrium condensation occurs,were also calculated and analyzed.