impeller

Abstract

This article is an impeller used in water jet propulsion systems for watercraft such as planing boats, and is characterized in that, whereas the outer surfaces of the impeller blades of ordinary impellers are mirror-finished, the outer surfaces of the impeller blades of this article are formed by shot blasting to create a random, fine, irregular shape. By creating a random, fine, irregular shape on the outer surfaces of the impeller blades in this way, water that has entered between the outer surfaces of the impeller blades and the inner surface of the impeller housing is repelled by the many small protrusions of the irregular shape, and the water pressure of the repelled water reduces the amount of air bubbles that enter between the outer surfaces of the impeller blades and the inner surface of the impeller housing from the outside, thereby preventing the impeller from running idly.

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