Bend Pipe Geometry to Suppress Inner-Side Flow Separation
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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 outward flow reduction.
Innovation Solution
A bend pipe design with an outer inclined surface and potential back-side eccentric portion, increasing the flow's inclination towards the inner side, combined with a larger cross-sectional area in the bend pipe portion to reduce centrifugal force and pressure loss, and incorporating inner inclined surfaces to prevent reverse flows.
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 is likely to cause 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 outward in the bend direction. This asymmetric configuration reduces the velocity of outward flow on the outer side while maintaining adequate boundary layer thickness on the inner side, preventing separation and reverse flow midway through the bend portion.
Solution Approach 2:
The patent applies local quality by creating different flow conditions at different locations within the bend pipe. The eccentric joint line configuration specifically addresses the outer side flow velocity while preserving boundary layer characteristics on the inner side, allowing each region to have optimized flow properties appropriate to its local requirements.
2Ease of operation
If a bend pipe portion is designed to change flow direction, then the flow direction is changed as required, but separation occurs on the inner side in the bend direction due to centrifugal force, causing pressure loss and efficiency deterioration
Solution Approach 1:
The patent applies asymmetry through the eccentric joint line configuration that positions the connection between inlet pipe and bend portion offset from the center toward the outer side. This asymmetric arrangement modifies the flow distribution to reduce centrifugal force effects on the inner side, preventing separation and reducing pressure loss while maintaining the required flow direction change capability.
Solution Approach 2:
The patent applies parameter changes by modifying the geometric parameters of the bend pipe, specifically the position of the joint line (eccentricity) and the curvature characteristics. These parameter adjustments optimize the flow path to minimize separation and pressure loss while achieving the necessary flow direction change for the application.
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
Effectively suppresses separation on the inner side of the bend pipe, reducing pressure loss and improving fluid machine efficiency by aligning the flow inward and reducing centrifugal force influence.
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
Data Source
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.