A Study on Reynolds Number Effects in Turbomachines

Typical space power units have a tendency to encounter low Reynolds numbers in the last turbine stages. Comprehensive test data on the effect of low Reynolds numbers on the efficiency of turbomachines are lacking. An attempt is made to assess this influence, using conventional aerodynamic arguments. By distinguishing between viscous and nonviscous losses some tentative values have been calculated which are in fair agreement with the few available test data. These considerations indicate that the stage pressure ratio and the specific speed affect the Reynolds number influence significantly.