Inclined Bend Pipe Structure for Inner-Side Separation Control
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Solution Overview
Problem
Bend pipes in fluid machines experience separation on the inner side due to centrifugal forces, leading to pressure loss and efficiency deterioration, as existing solutions only partially address the issue of reducing velocity on the outer side and do not effectively suppress separation on the inner side.
Innovation Solution
A bend pipe design with an outer inclined surface and potential back-side eccentric portion, where the flow passage cross-sectional area is increased in the bend pipe portion to reduce centrifugal force, combined with inner inclined surfaces to guide the flow inward, thereby reducing separation and pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the joint line between the inlet pipe portion and the bend portion is formed eccentrically outward in the bend direction, then the velocity of the outward flow in the bend direction is reduced, but a thick boundary layer develops from the vicinity of the inlet of the bend portion at the inner side, which causes separation (reverse flow) midway in the bend portion
Solution Approach 1:
The patent applies asymmetry by forming the joint line between the inlet pipe portion and bend portion eccentrically positioned toward the inner side of the bend direction, rather than centrally or outward as in conventional designs. This asymmetric positioning changes the flow distribution pattern to prevent thick boundary layer formation on the inner side, thereby suppressing separation flow while maintaining acceptable velocity distribution.
Solution Approach 2:
The patent introduces a dimensional change by inclining the outer side surface of the bend pipe portion relative to the axial direction. This inclination creates a three-dimensional flow guidance effect that directs the flow inward toward the center of the bend, effectively counteracting the centrifugal force-induced separation on the inner side and improving flow attachment along the bend portion.
2Object-generated harmful factors
If the flow passage cross-sectional area is increased in the bend pipe portion, then centrifugal force effects are reduced, but the device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the cross-sectional area of the flow passage within the bend pipe portion. Specifically, the cross-sectional area is increased in the bend region compared to the inlet and outlet portions, which reduces the fluid velocity and consequently diminishes centrifugal force effects. This parameter adjustment effectively suppresses separation flow without requiring complex additional components.
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 effectively suppresses separation on the inner side of the bend pipe, reducing pressure loss and improving the efficiency of fluid machines by aligning the flow direction inward, thus minimizing centrifugal force effects and secondary flows.
Implementation Method 1
as a fluid flows through a bend pipe, the fluid may drift outward in the bend direction (outward with respect to the curvature radius) due to a centrifugal force
Implementation Method 2
separation may occur on the inner side in the bend direction (inner side with respect to the curvature radius)
Data Source
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AI summary
A bend pipe for supplying a fluid to a fluid machine or discharging the fluid from the fluid machine, wherein, provided that: a line including a pipe axial center line of an inlet pipe portion and an extension line thereof is defined as a line L; a line including a pipe axial line of an outlet pipe portion and an extension line thereof is defined as a line M; and a direction parallel to an intersection line formed by a plane orthogonal to the line M and a plane orthogonal to the line M is defined as a direction I, and when, as seen from the direction I, a side of the line M on which the inlet pipe portion exists is defined as a front side and a side of the line M on which the inlet pipe portion does not exist is defined as a back side, a side surface on an outer side with respect to a bend direction of a bend pipe portion includes an outer inclined surface on the back side of the line M, the outer inclined surface being inclined so that a distance from the line M decreases toward a downstream side.