Studies on the Characteristics of Axial-Flow Pumps : Part 5, Experimental Investigation on the Impeller Performance

Abstract

By using the experimental results shown in the previous reports, the writer treated the relation between the capacities and theoretical heads, and discussed the effects due to the types of impeller. The results obtained are as follows : 1. The hydraulic loss in impeller blades becomes maximum at critical discharge q_c, and it has quite different tendencies before and behind q_c. 2. In the axial flow domain (capacities larger than q_c), the characteristics of an aerofoil section at the mean effective radius are derived for the mean flow at the inlet and outlet from impeller blades. It, thereafter, is found that the values of lift coefficients are in good agreement with the test data for the single airfoil for l/t≤0.8 (l : chord length, t : pitch), in spite of the change of setting angles and the number of blades. 3. In the centrifugal flow domain (capacities less than q_c), the energy losses in impeller blades can be shown fairly well in comparatively simple forms.