This study develops a wet steam modelling to solve the phase change process inside the blade cascade of a steam turbine. The comparative study is carried out to understand the impact of the dry gas model and wet steam model on predicting the flow behaviours in a steam turbine. The effect of the cutback of the trailing edge on the flow structure and nonequilibrium condensation is evaluated in blade cascades. The results show that the dry gas assumption without considering the phase change process predicts fraudulently flow separations near the trailing edge to induce oblique waves. The maximum liquid fraction can reach approximately 0.051 based on the wet steam flow modelling. The condensation-evaporation processes in the blade cascades cause a condensation loss of 0.118 MW. The stronger expansion flow is obtained to induce the earlier onset of the homogeneous nucleation process with an increasing cutback of the trailing edge. The 21% cutback of the trailing edge leads to strong flow separations on the suction side to severely deteriorate the flow condition in blade cascades. It suggests that the cutback of the trailing edge by 14% is acceptable to repair damaged blades considering the flow structure, nonequilibrium phase change and condensation loss.

这项研究开发了一种湿蒸汽模型，以解决汽轮机叶片级联内部的相变过程。进行比较研究是为了了解干气模型和湿蒸汽模型对预测蒸汽轮机中的流动行为的影响。在叶片叶栅中评估后缘的切边对流动结构和非平衡冷凝的影响。结果表明，不考虑相变过程的干燥气体假设可预测后缘附近的气流分离，从而诱发倾斜波。根据湿蒸汽流模型，最大液体分数可以达到约0.051。叶片叶栅中的冷凝水蒸发过程会导致0.118 MW的冷凝水损失。获得了更强的膨胀流，以引起后缘的切入增加而引起均相成核过程的更早开始。后缘减少21％会导致吸力侧出现强烈的气流分离，从而严重恶化叶片叶栅中的流动状况。这表明考虑到流动结构，非平衡相变和凝结损失，后缘减少14％可以修复损坏的叶片。