Centrifugal Compressor Hub With Through Hole and Seal
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Solution Overview
Problem
Centrifugal compressors with through holes in the impeller suffer from reduced pressure ratio and increased power consumption due to air current leakage and backflow, which also increase the moment of inertia and thrust load on the impeller.
Innovation Solution
A centrifugal compressor design featuring a hub with an external radial surface of gradually increasing diameter and a back surface, equipped with a projection in the casing that accommodates a through hole penetrating from the back surface to the external radial surface, avoiding the blades and incorporating backflow and leakage suppressors to prevent air current leakage and backflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a through hole is formed in the hub to reduce moment of inertia and thrust load, then the moment of inertia and thrust load are reduced, but air current leakage and backflow occur causing reduced pressure ratio and increased power consumption
Solution Approach 1:
A seal member is introduced as an intermediary component between the through hole and the air current path. The seal member selectively blocks the passage of air current through the through hole while allowing the through hole to maintain its function of reducing moment of inertia and thrust load. This resolves the contradiction by mediating between the structural benefit of the through hole and the aerodynamic requirement to prevent leakage.
Solution Approach 2:
The seal member is positioned specifically at the through hole location rather than sealing the entire hub surface. This localized sealing approach prevents air current leakage through the through hole while maintaining the overall aerodynamic flow path along the external radial surface, thus preventing backflow and maintaining pressure ratio without adding excessive complexity.
2Weight of moving object
If a through hole is formed in the hub to reduce moment of inertia and thrust load, then the moment of inertia and thrust load are reduced, but air current leakage and backflow occur causing reduced pressure ratio
Solution Approach 1:
The seal member acts as a mediator that allows the through hole to fulfill its structural purpose while preventing its aerodynamic drawback. By selectively blocking air current passage at the through hole, the seal member prevents both leakage and backflow, thereby maintaining the pressure ratio without compromising the moment of inertia reduction benefit.
Solution Approach 2:
The harmful function of the through hole (air current passage) is extracted and blocked by the seal member, while the useful function (structural weight reduction) is preserved. The seal member effectively separates the aerodynamic flow path from the structural through hole, allowing the through hole to exist without causing pressure ratio degradation.
3Weight of moving object
If air current flows through the through hole to the back surface, then the moment of inertia is reduced, but air current leakage occurs reducing compressor efficiency
Solution Approach 1:
The seal member is introduced as an intermediary that blocks the direct connection between the through hole and the back surface air current path. This prevents air current from leaking through the through hole to the back surface, thereby maintaining compressor efficiency while preserving the moment of inertia reduction benefit of the through hole structure.
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 reduces the moment of inertia and thrust load on the impeller while maintaining a high pressure ratio by suppressing air current leakage and backflow, thereby enhancing the compressor's efficiency and performance.
Implementation Method 1
an impeller fixed to the rotation shaft and rotating together with the rotation shaft
Data Source
AI summary
A centrifugal compressor comprises a rotation shaft, an impeller, and a casing. The impeller has a hub and a plurality of blades. The casing has an opposite surface facing a back surface of the hub, and a projection projecting from the opposite surface toward the impeller. The hub is provided with an accommodation space that accommodates the projection. The accommodation space includes a through hole penetrating the hub from the back surface toward an external radial surface. The through hole opens while avoiding the blades.