Numerical investigations for effect of supplementary steam on aerodynamic performance of turbine stage and rotordynamics of stator seal

To investigate the influence of supplementary steam on the aerodynamic performance of turbine through flow and rotordynamic characteristics of diaphragm seal, three-dimensional Reynolds-Averaged Navier-Stokes (RANS) and k-Ε turbulent model are used to analyze the aerodynamic performance of turbine stage without supplementary steam and with two kinds of supplementary steam. The inlet and outlet boundary conditions of the turbine stage stator seal at three kinds of supplementary steam operating conditions were specified according to flow field calculations. The unsteady fluid excitation rotordynamic characteristics of the stator seal were numerical calculated using multi-frequency elliptical whirling orbit model and dynamic grids. The numerical results show that the supplementary steam jets impacts on the hub regions of the downstream stator blade and results in the vortex flow. This flow behavior leads to the non-uniform inlet aerodynamic parameters at the entrance of the stator blade. The aerodynamic performance decreases with the increase of the mass flow rate of the supplementary steam. The supplementary steam jet changes the inlet preswirl and aerodynamic parameters of the downstream stator seal. The unsteady fluid excitation force and rotordynamic coefficients of the stator seal also change with the variation of the inlet flow parameters. ©, 2015, Xi'an Jiaotong University. All right reserved.