INVESTIGATING THE EFFECTS OF OUTLET PRESSURE FROM STEAM TURBINE BLADE ON WETNESS AND ENTROPY GENERATION WITH CONSIDERATION OF NON-EQUILIBRIUM CONDENSATION

Abstract

Steam turbines are one of the main elements of a power plant that steam thermal energy turns into rotational energy. Due to condenser pressure changes, the pressure at the end of steam turbines changes. In this study, the Bakhtar blade is used, and the effects of changes in the pressure outlet of the blade on the flow behavior are investigated. In this research, 62.56 kPa, 72.56 kPa, 82.56 kPa, 92.56 kPa, and 102.56 kPa are considered for the pressure at the end of the steam turbine blade. First, the CFD solution results are compared with the laboratory data of the Bakhtar turbine's blade. Then, the effect of outlet pressure is examined. Regarding obtained results, the proposed numerical solution can properly predict the experimental data. By the growth of the outlet pressure of the steam turbine blade, the Mach number decreases and the pressure and temperature distribution increase. As the pressure increases from 62.56 kPa to 102.56 kPa, the average Mach number decreases by 29.8% at the outlet, and the average temperature at the outlet increases by 3.9%. The nucleation rate does not have a noticeable change. However, liquid mass fraction decreases with the increase in outlet pressure. By increasing the pressure from 62.56 kPa to 102.56 kPa, the average wetness decreases by 39.5% at the outlet. This study shows that condenser pressure changes affect the liquid phase produced in the end blade of the steam turbine.