Multi-objective optimization of the wet at the blade's inlet and surface heating for wet steam flow in turbine blade cascade by TOPSIS method

In the last stages of the steam turbine, due to the reduction in pressure, the inlet flow is accompanied by droplets. The innovation in this study pertains to determining the optimal amount of surface heating (SH) and wetness at the inlet (WAI) using the TOPSIS method for the turbine blade cascade. In this context, three conditions have been simulated: WAI (wetness at the inlet), SH (surface heating), and simultaneously with WAI and SH. The kinetic energy ratio (KER), erosion rate ratio (ERR), wetness fraction ratio (WFR), condensation loss ratio (CLR), and cost price (CP) are considered objective functions. Navier-Stokes equations coupled with nucleation and droplet growth equations are obtained together by applying SST k - omega. Numerical method validation is conducted with Bakhtar's data. Finally, case 1-B is proposed as the optimal case. In this case, the SH is equal to 180 (kWm2) and the average wetness fraction is equal to 1 %. The comparison of the optimal case with the original case indicates that the kinetic energy ratio is increased by 8.68 %, the erosion rate ratio is reduced by 14.17 %, the wetness fraction ratio is reduced by 2.8 %, and the condensation loss ratio is decreased 0.91 %.