Pump Suction Pipe Bent Portion Design for Cavitation Suppression
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Solution Overview
Problem
Conventional pump suction pipes with bent portions suffer from secondary flow generation, leading to cavitation and noise issues due to complex designs and additional components like dividers, which increase costs and complexity, and result in recirculation that can damage equipment.
Innovation Solution
A simplified design for the pump suction pipe bent portion where the distance from the reference point to the inner end is monotonically increased and to the outer end is monotonically decreased, forming a smooth, elbow-shaped structure without guide vanes, reducing pressure gradients and secondary flows, and eliminating the need for dividers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If guide vanes are inserted into the bent pipe to suppress secondary flow, then cavitation is reduced, but device complexity increases
Solution Approach 1:
The invention extracts and eliminates the guide vanes from the bent pipe structure, achieving cavitation suppression through the geometric design of the bent pipe itself rather than through additional internal components. The bent pipe is designed with a specific curvature radius relationship where R2 ≥ 1.5R1, allowing the flow to follow the pipe contour naturally without requiring guide vanes.
Solution Approach 2:
The bent pipe is divided into two distinct sections: a first bent pipe section with curvature radius R1 and a second bent pipe section with curvature radius R2. This segmentation allows each section to handle different flow characteristics, with the gradual transition from the tighter first section to the more gradual second section suppressing secondary flow and cavitation without additional components.
2Object-affected harmful factors
If dividers are provided in the bent pipe to improve flow, then cavitation is suppressed, but device complexity increases
Solution Approach 1:
The invention completely removes the need for dividers by incorporating flow-guiding geometry directly into the bent pipe structure. The specific curvature radius relationship (R2 ≥ 1.5R1) creates natural flow guidance that eliminates the need for additional internal divider components.
Solution Approach 2:
The bent pipe utilizes carefully designed curved geometries with specific radius relationships. The first bent pipe section has curvature radius R1 and the second has curvature radius R2 where R2 ≥ 1.5R1, creating smooth flow transitions that prevent cavitation without requiring dividers.
3Object-affected harmful factors
If a complex bent pipe design with guide vanes is used, then secondary flow is suppressed, but manufacturing cost increases
Solution Approach 1:
The invention removes guide vanes and complex internal structures, achieving secondary flow suppression through the bent pipe's own geometry. This simplification directly reduces manufacturing complexity and cost while maintaining effective flow control.
Solution Approach 2:
The bent pipe employs a two-section curved design with specific radius relationships (R2 ≥ 1.5R1) that naturally guide flow and suppress secondary currents. This geometric approach is simpler and more cost-effective to manufacture than complex internal vane structures.
4Length of stationary object
If the bent pipe has a tight curvature to fit space constraints, then installation is easier, but cavitation increases
Solution Approach 1:
The bent pipe is segmented into two sections with different curvature radii. The first section (R1) provides compact space utilization while the second section (R2 ≥ 1.5R1) provides a gradual transition that prevents cavitation, achieving both space efficiency and cavitation suppression.
Solution Approach 2:
The bent pipe uses a two-stage curved geometry where the first section has curvature radius R1 for compactness and the second section has curvature radius R2 ≥ 1.5R1 for cavitation suppression. This graduated curvature approach fits space constraints while preventing harmful cavitation effects.
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
This design effectively suppresses secondary flows and cavitation generation, reducing the impact of recirculation and simplifying the pipe structure, thereby minimizing noise and operational issues while lowering production costs.
Implementation Method 1
When the flow passes through a bent portion, the centrifugal force is applied to the liquid. The centrifugal force increases in proportion to the square of the velocity in the arc-like direction (arc circumferential direction) along the bent portion, and is applied in the direction (arc radial direction) from the inner circumferential side to the outer circumferential side of the bent portion.
Implementation Method 2
a pressure gradient in the radial direction of the arc occurs in the liquid bent like an arc by passing through the bent portion due to the centrifugal force applied in the radial direction of the arc. In this case, the pressure is high on the outer circumferential side, and low on the inner circumferential side.
Implementation Method 3
the distance from the reference point to an inner end of the suction pipe bent portion is monotonically increased from the upstream side to the downstream side on a vertical cross-section... This design effectively suppresses secondary flows and cavitation generation
Implementation Method 4
If a liquid flows into an impeller suction port after passing through the bent portion while the secondary flow remains in the pump suction pipe, an area of a discrepancy between the inflow angle of a liquid at the impeller suction port and the blade angle of the impeller is generated... Under the pump operation conditions where the pressure of the inlet of the impeller is low, cavitation is likely to be locally generated
Data Source
AI summary
The present invention is to suppress generation of cavitation in an impeller of a pump and disproportion of generation areas thereof by suppressing a secondary flow generated in a bent portion of a pump suction pipe. A pump suction pipe includes: a suction pipe outlet portion that is connected to an impeller suction port of a pump and is arranged in the up-and-down direction; a suction pipe inlet portion that is arranged in the lateral direction; and a suction pipe bent portion that connects the suction pipe outlet portion and the suction pipe inlet portion to each other and changes a flow from the lateral direction to the up-and-down direction. The distance from a reference point to an inner end of the suction pipe bent portion is monotonically increased from the upstream side to the downstream side on a vertical cross-section.