Predicting the Axial Steam Turbine's Performance using 3D Computational Fluid Dynamics

Abstract

To generate electricity, steam turbines are the primary prime movers. With horsepower ratings exceeding 10,000 HP, these turbines discover significant uses for naval propulsion in addition to electricity production. We use Ansys-CFX CFD software to model and analyze the performance of a single axial turbine stage, which has 58 blades in the rotor and 60 blades in the stator. The working fluid for the turbine stage was determined to be superheated steam with temperatures of 500 K and 600 K at 2 & 3 pressure, respectively. The working fluid's thermodynamic characteristics are sourced from the IAPWS97 database. When designing turbo equipment, it is essential to first do thorough simulation studies to identify potential issues, and then determine the best operating conditions. Under both inlet situations, the turbine is operated at various speeds, varying between 6,000 and 12,000 rpm. At a greater pressure of 3 bar, the power output more than doubles, but the efficiencies remain almost the same, exceeding 90%, regardless of the input circumstances. Maximum efficiency were achieved at 8000 rpm at 2 pressure and 10000 rpm at 3 bar, which ranged by 15 to 20%. Stator blades exhibit a significant rise in kinetic energy, suggesting a highly efficient nozzle. Due to the fact that the relative mach number is dependent on the rotor speed and since the sonic velocity decreases as temperatures fall, it is seen that both the temperatures and the relative mach number drop as the speed increases.