Effect of Stage Axial Distances on the Aerodynamic Performance of Three-Stage Axial Turbine Using Experimental Measurements and Numerical Simulations

The stage axial distance significantly influences the aerodynamic performance of turbines under some constraints. Experimental measurements and numerical simulations are used to analyze the effect of stage axial distances on the aerodynamic performance of three-stage axial turbine in this work. The aerodynamic performance of three-stage axial turbine with three different stage axial distances is experimentally measured at the air turbine test rig of Dongfang Steam Turbine Co. LTD. Experimental results show that efficiency increases when the stage axial distance decreases for the geometry under study with relative stage distance ranged from 0.14 to 0.35, and the effect of stage axial distance on the optimization velocity ratio here is very limited. In addition, unsteady Reynolds-Averaged Navier-Stokes (RANS) simulations were carried out with nonlinear harmonic method to analyze the detailed flow field of the experimental three-stage axial turbine. The numerical aerodynamic efficiency of three-stage axial turbine is in good agreement with the experimental data. Furthermore, the small stage axial distance is preferred for the higher efficiency. The detailed flow field and aerodynamic parameters of three-stage axial turbine are also illustrated and discussed.