Centrifugal Pump Impeller Vane Recessed Step for Self-Priming
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Solution Overview
Problem
Conventional centrifugal pumps experience reduced self-priming performance due to suppressed swirling flows at the end portions of impeller vanes, leading to decreased air suction and increased cavitation.
Innovation Solution
The centrifugal pump design features an impeller with radially arranged vanes having a recessed step surface on their rotational-direction rear end, which develops greater swirling flows and alleviates fluid stoppage, enhancing self-priming performance and suppressing cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the impeller vanes have slanted surfaces to suppress cavitation, then cavitation is reduced, but swirling flows at the end portions decrease leading to lowered self-priming performance
Solution Approach 1:
The vane end portion is segmented into multiple regions with different surface characteristics: a slanted surface region for cavitation suppression and a recessed step surface region for swirling flow generation. This segmentation allows each region to perform its specific function without interfering with the other, resolving the contradiction between cavitation suppression and self-priming performance.
Solution Approach 2:
Different parts of the vane end portion are given different local qualities: the slanted surface provides smooth flow transition to suppress cavitation, while the recessed step surface creates turbulence and swirling flows to enhance self-priming. This local differentiation allows simultaneous achievement of both cavitation suppression and self-priming performance.
2Reliability
If the impeller vanes have smooth surfaces to reduce fluid stoppage, then cavitation is suppressed, but air suction capability decreases
Solution Approach 1:
The vane surface is segmented into a smooth slanted portion for reducing fluid stoppage and cavitation, and a recessed step portion for generating swirling flows that enhance air suction. This segmentation allows the smooth surface to suppress cavitation while the recessed step creates the necessary flow patterns for air entrainment.
Solution Approach 2:
The recessed step surface acts as an intermediary element that transforms the smooth flow from the slanted surface into swirling flows. It mediates between the conflict of smooth flow (for cavitation suppression) and swirling flow generation (for air suction), creating turbulence that enhances air entrainment while maintaining overall flow smoothness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves improved self-priming performance by effectively entraining air and reducing cavitation through enhanced fluid flow and mixing, while maintaining efficient fluid discharge.
Implementation Method 1
swirling flows can be developed at a boundary portion of the outer peripheral surface where the outer peripheral surface starts switching to the recessed step surface and at a rear end portion of the recessed step surface
Implementation Method 2
great swirling flows can be developed to entrain air present within the volute
Implementation Method 3
stoppage of fluid can be alleviated in a stepwise fashion over a region where the vane progressively approaches the inner peripheral surface of the volute, so that occurrence of cavitation can be suppressed
Implementation Method 4
fluid sucked into the volute by rotation of the impeller is discharged to outside of the centrifugal pump
Data Source
AI summary
An impeller includes a disk-shaped hub and a plurality of vanes provided radially on the surface of the hub. The plurality of vanes are formed in a whirling pattern about the center of rotation of the impeller, and each of the vanes has an outer peripheral surface facing the inner peripheral surface of the volute. A rotational-direction rear end portion of the outer peripheral surface of each of the vanes has a recessed step surface formed thereon. The rotational-direction rear end of the recessed step surface of each of the vanes is formed to define an edge shape with respect to a rotational-direction rear end surface of the vane.