Influence of impurity particles on non-equilibrium condensation flow characteristics in steam turbine

In a steam turbine, the rapid expansion of steam can induce non-equilibrium condensation, which is significantly influenced by the presence of impurities. The primary purpose of this investigation is to determine the optimal particle conditions to minimize wet steam losses in heterogeneous condensation flows. First, a numerical model is improved to simulate heterogeneous condensation, focusing on the nucleation process on solid particle surface. Then, the model is applied to investigate heterogeneous condensation characteristics within the Moses-Stein nozzle and Dykas cascade. Finally, the impact of heterogeneous condensation on wet steam loss is evaluated in terms of thermodynamic loss ratio (TLR) and wetness fraction ratio (WFR). Research results indicate that heterogeneous condensation significantly suppresses condensation compared to homogeneous condensation and markedly improves distribution of flow field parameters within the nozzle. However, wetness increases with higher particle concentration and particle radius. Under optimal particle conditions, the wetness at the nozzle outlet is reduced by 8 %, effectively decreasing wet steam loss due to condensation. For the Dykas blade cascade, with a particle concentration of 1 × 1016 kg−1 and a particle radius of 1 × 10−9 m, thermodynamic loss is reduced by approximately 15 %, and wetness decreases by about 5 % compared to homogeneous condensation.