In centrifugal pump terminology, what is the term for the central region where fluid enters the impeller?

• A. Eye
• B. Crown
• C. Bore
• D. Duct

Answer: (A)

The central region where fluid enters the impeller is called the eye. This is the entry point that feeds the vane passages, usually with axial flow into the impeller. The eye sets how the fluid starts its journey through the impeller, and its size and shape influence how evenly the flow enters, the velocity distribution, and overall pump performance. A properly designed eye helps minimize flow separation and pre-swirl, leading to smoother, more efficient operation. Terms like bore refer to the inner diameter or hub area, crown is not the standard term for the inlet region, and duct is a general piping term, not the specific entry region of the impeller.