Composite Rings for Impeller-Shaft Attachment
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Solution Overview
Problem
Centrifugal compressors face failures due to impeller deformation at high angular velocities, as current attachment methods fail to securely maintain impellers on the shaft, leading to sudden performance drops or catastrophic failures.
Innovation Solution
Attaching composite rings with greater specific stiffness and strength to both the front and back lips of impellers, using methods like filament winding, to restrain impellers on the shaft and prevent deformation under axial rotational loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat shrinking is used to attach impeller to shaft, then initial attachment is achieved, but impeller deforms and slips at high angular velocities
Solution Approach 1:
The patent applies composite materials by attaching a composite ring to the impeller back lip. This composite ring has different material properties than the metal impeller, providing greater stiffness and strength to resist centrifugal forces at high angular velocities. The composite material compensates for the deformation that occurs in the metal impeller under operational loads, preventing slippage and maintaining reliable attachment to the shaft.
Solution Approach 2:
The patent segments the impeller assembly by adding a separate composite ring component to the back lip of the impeller. This segmentation allows the composite ring to independently bear the centrifugal loads and prevent deformation, while the main impeller body continues to perform its primary function of moving gas. The composite ring acts as a separate functional element that addresses the attachment reliability issue without redesigning the entire impeller.
2Reliability
If retaining ring is added to impeller back, then attachment is improved, but uneven deformation forces detach the ring at high angular velocities
Solution Approach 1:
The patent replaces the metal retaining ring with a composite ring that has superior stiffness-to-weight ratio and strength properties. The composite material distributes the deformation forces more evenly across the impeller back lip, preventing the concentration of stresses that would lead to ring detachment. This material substitution maintains attachment reliability while reducing the structural complexity compared to a traditional metal retaining ring design.
3Reliability
If composite ring is attached to impeller lips, then deformation is prevented, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-forming the composite ring with the appropriate geometry and material properties before attachment to the impeller. The composite ring is manufactured as a separate component with optimized fiber orientation and resin distribution to provide the necessary stiffness and strength. This preliminary preparation allows for quality control and simplifies the final assembly process, where the pre-fabricated composite ring is attached to the impeller back lip using standard bonding or mechanical attachment methods.
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 composite rings effectively constrain impellers, preventing deformation and ensuring secure attachment throughout the operational angular velocity window, thereby enhancing the reliability and performance of centrifugal compressors.
Implementation Method 1
the difference in the radius of the impeller with respect to the radius of the axial shaft to which the impeller is mounted provides sufficient centrifugal force differential to generate failure conditions
Implementation Method 2
first heated to expand their attachment diameter, then mounted on the shaft and allowed to shrink and cool on the shaft to provide a tight fit thereto
Data Source
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AI summary
Systems and methods for attaching one or more impellers to a shaft and attaching composite rings to a back and front lip on each impeller to secure the impellers for high angular velocity operation. The composite rings are constructed of a material that provides a greater specific strength and greater specific stiffness relative to the material of the impellers. In multi-impeller assemblies, an impeller spacer is attached between each pair of impellers.