Centrifugal Compressor Scroll Ridge for Flow Separation Control
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Solution Overview
Problem
Centrifugal compressors experience efficiency losses due to fluid separation at the passage connecting portion, particularly caused by interference between fluid flow and swirling flow over ridge and tongue portions, which are not adequately addressed by existing scroll structures.
Innovation Solution
A scroll structure with a ridge portion that gradually increases in height towards the tongue portion, with a starting position at an angle of 8 degrees or less in the circumferential direction, and a protruding height of 10% or less of the scroll passage height, designed to reduce interference and fluid separation, along with a circularizing cross-sectional shape transition from the scroll to the outlet passage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the cross-sectional area of the passage connecting portion is reduced to suppress recirculation flow, then loss is reduced, but fluid separation occurs at the ridge portion causing efficiency degradation
Solution Approach 1:
The patent applies local quality by giving different geometric characteristics to different portions of the passage connecting portion. Specifically, the ridge portion has a controlled protruding height (0.05-0.15 times the height of the scroll passage at the winding start portion) and the tongue portion has a specific curvature radius (0.05-0.15 times the height of the scroll passage at the winding start portion). This localized geometric optimization allows the passage to suppress recirculation flow while preventing fluid separation, thereby resolving the contradiction between reducing energy loss and maintaining compressor efficiency.
2Productivity
If the ridge portion protrudes highly to separate flows, then recirculation is suppressed, but fluid separation occurs causing loss
Solution Approach 1:
The patent applies parameter changes by precisely controlling the protruding height of the ridge portion as a geometric parameter. The protruding height is set to 0.05-0.15 times the height of the scroll passage at the winding start portion, which is an optimized range that allows sufficient flow separation to suppress recirculation while preventing excessive protrusion that would cause fluid separation. This parameter optimization resolves the contradiction between suppressing recirculation and preventing energy loss.
3Ease of manufacture
If the passage connecting portion geometry is simplified, then manufacturing is easier, but fluid flow control and loss suppression are insufficient
Solution Approach 1:
The patent applies local quality by introducing specific geometric features (ridge portion with controlled protruding height and tongue portion with controlled curvature radius) only at the critical passage connecting portion where winding start and end portions intersect. The rest of the scroll passage maintains a simpler spiral geometry. This localized complexity approach enables effective fluid flow control and loss suppression while keeping the overall manufacturing process relatively simple, resolving the contradiction between ease of manufacture and energy loss suppression.
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 configuration effectively suppresses fluid separation and associated losses, enhancing the efficiency of the centrifugal compressor over a wide operating range.
Implementation Method 1
the fluid flow that tries to flow over the ridge portion and the swirling flow interfere with each other, causing the fluid to separate from the inner peripheral surface of the scroll passage near the tongue portion
Implementation Method 2
provides kinetic energy to a fluid through the rotation of the impeller and obtains a pressure increase due to centrifugal force by discharging the fluid outward in the radial direction
Data Source
AI summary
A scroll structure of a centrifugal compressor according to an embodiment is a scroll structure of a centrifugal compressor having a scroll passage formed in spiral shape, comprising: a tongue portion separating the scroll passage from an outlet passage connected to the downstream side of the scroll passage at the most downstream position of the scroll passage in a passage connecting portion where a winding start portion and a winding end portion of the scroll passage intersect; and a ridge portion protruding from an inner peripheral surface of the scroll passage on the axially downstream side of the centrifugal compressor toward the axially upstream side of the centrifugal compressor, with a protruding height toward the axially upstream side gradually increasing toward the tongue portion from a starting position that is located upstream from the tongue portion in the scroll passage. The starting position is a position at an angle of 8 degrees or less in the circumferential direction of the centrifugal compressor from the tongue portion toward the upstream side of the scroll passage.