Numerical investigations on effect of streamwise micro-groove on aerodynamic performance of ruled surface impeller

In the paper the freeform blade surface of an centrifugal impeller is replaced by a ruled surface for the purpose of reducing the manufacture cost. It is found that the impeller with a ruled surface leads to the obvious deteriorations on the aerodynamic performance and flow field. Then a streamwise micro-grroove is adopted on the ruled surface impeller and its effect on the impeller performance is analyzed. The results indicate that, the streamwise micro-groove can increase the pressure ratio and efficiency evidently, while it has no effect on the stable operating range of impeller. Furthermore, the performance of a ruled surface impeller can reach to almost the same level with that of a freeform surface impeller when an appropriate micro-groove design is used.