Impeller Preloading Bands for Axial Deflection Control
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Solution Overview
Problem
Rotary machines with heavy impellers require additional containment, increasing weight and reducing efficiency due to axial deformations caused by centrifugal forces and thermal expansion, which is undesirable for aircraft applications.
Innovation Solution
The implementation of preloading bands made from high-strength, low-weight materials around annular protrusions on the impeller hub to counteract centrifugal forces and reduce axial deflections, allowing for a lighter impeller design while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thick and heavy metal walls are used in impeller hubs to reduce axial deformations, then axial deformation is reduced, but weight increases
Solution Approach 1:
The impeller hub is segmented into a lightweight base structure with separate preloading bands applied to specific annular protrusions. This segmentation allows the preloading bands to provide localized axial support only where needed, rather than requiring the entire hub to be made of heavy material, thus reducing overall weight while maintaining deformation control.
Solution Approach 2:
Preloading bands are applied in advance to the annular protrusions to create preliminary compressive forces that counteract the centrifugal forces generated during rotation. This preliminary action prevents axial deformation before it occurs during operation, eliminating the need for heavy reactive structures.
2Strength
If heavy impellers are used to maintain structural integrity, then structural integrity is improved, but containment requirements increase
Solution Approach 1:
The preloading bands change the stress distribution parameters within the impeller hub by introducing compressive preloads. This alters the mechanical parameters so that lightweight materials can achieve the same structural integrity as heavier materials would provide alone, reducing the need for heavy containment structures.
3Stability of the object's composition
If preloading bands are added to counteract centrifugal forces, then axial deflections are reduced, but device complexity increases
Solution Approach 1:
The preloading bands are implemented as flexible elastic elements that can conform to the annular protrusions. These thin film-like structures provide the necessary stabilizing force without adding significant structural complexity, as they simply encircle the protrusions and exert radial pressure to prevent axial deflection.
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 solution reduces axial deflections and stabilizes the impeller geometry, leading to increased performance and reliability of rotary machines with reduced weight and containment requirements, making them more suitable for aircraft use.
Implementation Method 1
preloading bands that place elastic force on impellers
Implementation Method 2
Axial deformation reduces efficiency of rotary machines with impellers... deform axially when rotating
Data Source
AI summary
An impeller includes a hub. The hub has a first end and a second end and includes an impeller disk at the second end of the hub. The impeller disk includes a first annular protrusion extending from the impeller disk. A first pocket is in a radially outer side of the first annular protrusion. The impeller also includes a first preloading band positioned in the first pocket. The first preloading band encircles the radially outer side of the first annular protrusion. The impeller also includes blades connecting to a radially outer surface of the hub.