Velocity Distributions in the Impeller Passages of Centrifugal Pumps : Effects of Outlet Edge Shape of the Impeller Blades on the Pump Performance

Performance of a centrifugal pump was examined experimentally when the trailing edges of the impeller blades were designed in various shapes, and the change in the pump performance was discussed in relation to the velocity variation due to the shape changes. Sharpening of the blade on its pressure or suction side caused a change in the exit flow angle as well as a decrease in the meridian component of velocity, and an increase in the pump head was brought about. The increase was more pronounced in the pump with impeller blades sharpened on the suction side edge due to a larger increase in Cu2. A relationship between the increase in the pump head and the blade edge sharpening was investigated experimentally and a simple theory to predict it is presented.