Centrifugal Compressor Impeller Rigidity Design
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Solution Overview
Problem
Centrifugal compressors face challenges in enhancing rigidity and compression performance due to the adverse effects of increased blade thickness on compression performance and vibration characteristics, particularly at the outlet side of the impeller, where bending stress is significant.
Innovation Solution
The impeller design incorporates a high-rigidity region with a large plate thickness and inclination angle, adjacent to a low-rigidity region with a small plate thickness and inclination angle, allowing for a rigidity difference that directs bending stress to the high-rigidity region, while maintaining a thin plate thickness in low-rigidity areas to enhance compression performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the plate thickness of the blade is increased to enhance rigidity, then the rigidity against bending stress is improved, but the compression performance is significantly degraded and the weight increases
Solution Approach 1:
The blade is divided into multiple regions along the flow path extending direction, with each region having different plate thicknesses. The high-rigidity region has a larger plate thickness to resist bending stress, while the low-rigidity region has a smaller plate thickness to maintain compression performance and reduce weight. This local differentiation resolves the contradiction by applying thickness increases only where structurally necessary.
Solution Approach 2:
The blade structure is segmented into distinct high-rigidity and low-rigidity regions based on the flow path extending direction. This segmentation allows independent optimization of each region's thickness to serve different functional requirements - the high-rigidity region handles structural loads while the low-rigidity region maintains aerodynamic efficiency.
2Strength
If the plate thickness of the blade is increased to enhance rigidity, then the rigidity against bending stress is improved, but the vibration characteristics are affected due to weight increase
Solution Approach 1:
Instead of uniformly increasing blade thickness throughout, the invention applies increased thickness only in the high-rigidity region where structural support is needed. The low-rigidity region maintains smaller thickness, significantly reducing the overall weight increase while still providing adequate rigidity where required to resist bending stress.
3Strength
If the inclination angle of the blade is increased to enhance rigidity, then the rigidity is improved, but the compression performance may be affected
Solution Approach 1:
The inclination angle is differentiated across different regions of the blade. The high-rigidity region has a larger inclination angle to enhance structural rigidity, while the low-rigidity region has a smaller inclination angle optimized for compression performance. This local differentiation allows both requirements to be satisfied simultaneously in different parts of the blade.
Data Source
AI summary
An impeller includes a disk formed in a disk shape about an axis, and a plurality of blades provided at intervals in a circumferential direction on one side in the axial direction of the disk. The blades define a flow path extending from one side in the axial direction toward a radial outer side and include a low-rigidity region and a high-rigidity region. The low-rigidity region has an inlet, an outlet of the extending region of the flow path, a relatively small plate thickness, and has a relatively small inclination angle with respect to the disk. The high-rigidity region adjacent to the low-rigidity region has a relatively large plate thickness, and a relatively large inclination angle with respect to the disk.