关于汽轮机内湿蒸汽两相凝结流动的研究进展

Advances in the Study of the Wet Steam Two-phase Condensation Flow Inside Steam Turbine

汽轮机内的湿蒸汽非平衡凝结流动会导致机组效率降低和叶片水蚀损坏。由于两相流动远比单相流动复杂,通过实验难以测量其凝结特性。对此,通过分析国内外湿蒸汽两相流理论和实验研究现状,总结了现有的3种研究方法,并指出研究中存在的问题,讨论了两相流凝结机理及其求解方法,阐述了几种湿蒸汽测量方法优点及不足之处。分析指出:凝结相变过程十分复杂,传热传质在微米级水平发生,因此,有必要发展一种考虑两相间耦合的凝结模型。结合两相流数值研究的现状,对汽轮机两相流数值的求解方法进行阐述。湿蒸汽两相流研究为汽轮机通流部分设计和改造提供了理论参考。

The wet steam non-equilibrium condensation flow inside steam turbines may result in a decline of the efficiency of the units and damage to blades due to water erosion. In view of the fact that a two-phase flow is far more complicated than a single-phase flow,it is difficult to measure its condensation characteristics through various tests. In such a case,the currently available three research methods were summarized through analyzing the latest research findings in the study of the wet steam two-phase flow theory both at home and abroad and its experimental study and the problems existing in the studies above-mentioned were also pointed out. Furthermore,the mechanism governing the condensation of a two-phase flow and the method for seeking its solutions were discussed and the merits and demerits of several wet steam measurement methods were expounded. The research results show that the condensation and phase process is very complicated and the heat and mass transfer occurs at the micrometer level. Therefore,it is necessary to develop a condensation model with the coupling between two phases being taken into consideration. In combination with the status quo of the two-phase flow numerical study,the numerical methods for seeking solutions to two-phase flows inside steam turbines were expounded. The foregoing can offer a theoretical reference for the de-sign and reconstruction of the flow path in steam turbines