Figure 8. 6 stages counter-rotating turbine design

Selection of rotation speed for this design was performed in the same way, i.e. using DoE study for range of rotation speed variables basing on the highest efficiency criterion. For 6 stages second shaft rotation speed was chosen equal to 4500 RPM

Figure 9. Efficiency chart vs rotation speeds (6 stages)

COMPARISON OF INITIAL AND COUNTER-ROTATING TURBINE PERFORMANCES

Integral Performances Comparison. Comparison of integral and detailed thermodynamic performances of both turbines is presented in this part. All results were obtained in 2D streamline calculation on 7 stations spanwise along all flow path. Task formulation used for calculation was “Finding mass flow rate for static outlet pressure”, calculation was performed with assumption of turbine operating on design mode, i.e. with incidence angles corresponding to minimal losses.