Cavitation Performance of a Pump With Independently Rotating Inducer and Impeller in Co-Rotation and Counter-Rotation Modes by Varying Rotor Speeds

Centrifugal pumps, consisting of an inducer and impeller, are used in various industries such as marine, aerospace, and nuclear. Typically, inducers and impellers in centrifugal pumps are fixed on the same shaft, having the same rotation direction and speed. Thanks to the use of independent rotation technology for the inducer and impeller, each can be rotated simultaneously at different speeds and in different directions. This article investigates the impact of varying the speed ratio between the inducer and impeller on the cavitation performance of centrifugal pumps equipped with an inducer as an innovative concept of allowing the rotors to rotate independently. Two inducers with identical geometry with opposite rotation directions are used to study the impact of speed in both corotation and counter-rotation modes. The cavitation performance of each mode has been analyzed for three different flow rates at varying inducer speeds. The development and structure of different types of cavitation occurring both in the inducer and in the space between the inducer and the impeller have been analyzed using a high speed camera. The findings indicate that the inducer in counter-rotation mode demonstrates enhanced cavitation performance. Increasing the speed ratio of the inducer relative to the impeller in this mode significantly improves the pump cavitation performance at different flow rates, while in the corotation mode, increasing the speed results in the cavitation performance drop.