Unsteady Pressure Distributions on the Impeller Blades of a Centrifugal Pump-Impeller Operating Off-Design

Pressure distributions on the impeller blades of a centrifugal pump were examined experimentally. The periodic pressure change caused in the suction and delivery pipes by the interaction between the rotating impeller blades and the dividing ridge of the volute casing was small. However, a noticeable cyclic change in the pressure on the blade surface was measured and related to the nonuniform pressure distribution in the volute casing at off-design flow rates. In a lower than normal range of flow rates this pressure fluctuation was largely increased near the leading edge of the blade due to the turbulent fluctuations and the flow separation from the blade surfaces. These periodic pressure changes have a large effect upon cavitation inception along the impeller periphery.