蒸汽透平静叶栅均质与非均质凝结流动数值研究

Numerical Study on Homogeneous and Heterogeneous Condensation Flow in Stator of Steam Turbine

基于存在自发凝结的均质与非均质湿蒸汽两相流动,开发了基于汽液两相双流体模型和k-ε-k p湍流模型的计算方法,对二维叶栅中的均质与非均质凝结流动进行了数值研究与分析,结果表明,蒸汽中含有一定量的杂质可以有效地改善湿蒸汽的流动状况,减小非平衡凝结流动产生的热力学损失。对由外界提供的凝结核心在不同的初始浓度和初始半径时,叶栅内的流动状态进行了数值分析,结果表明:非均质凝结流动随初始粒子半径的减小与浓度的增大而增强,自发凝结流动被逐渐抑制,但是完全的非均质凝结流动使得叶栅出口处的湿度增加,所以根据不同的叶栅应选择合适的初始粒子半径和浓度。

In view of spontaneous homogeneous and heterogeneous condensation flow of two-phase wet steam, a calculation method is developed based on vapor-liquid two-phase flow model and k -ε -kp turbulence model. The numerical study is conducted on the homogeneous and heterogeneous condensation flow in 2D cascade, and the results show certain quantity of foreign matter in steam can effectively improve the flow behavior of wet steam and reduce the thermodynamic loss due to non-equilibrium condensation flow. A numerical analysis is conducted for the flow behavior in cascades at different initial concentration and initial size of foreign condensation nucleus. The results show that, with smaller initial particle size and higher concentration, the heterogeneous condensation flow will become stronger and the spontaneous condensation flow is more restrained. However, completely heterogeneous condensation flow will increase the moisture at the outlet of cascades. Therefore, appropriate initial particle size and concentration shall be selected for different cascades.