Compressor Blade Tip Recesses for Stress Relief
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Solution Overview
Problem
Compressor blades in gas turbine systems experience high stresses due to elevated temperatures and pressures, leading to potential tip rubs and damage such as cracks or fractures, which decrease compressor efficiency and require shutdown for repair or replacement.
Innovation Solution
The implementation of a compressor blade tip geometry featuring symmetrical or asymmetrical recesses on both sides of the blade tip, extending between the leading and trailing edges, to reduce stress and increase rub tolerance, including configurations like concave, convex, S-shaped, and tapered recesses, formed by removing material while maintaining a mean camber line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If compressor blades operate under high temperature and pressure conditions, then the compressor can achieve high power output, but the blade tips experience high stresses leading to cracks or fractures
Solution Approach 1:
The patent applies local quality by introducing recesses specifically at the blade tip region where stresses are highest, while maintaining the original blade structure elsewhere. The recesses create a stress relief zone localized to the critical tip area, allowing the rest of the blade to maintain its strength for power generation.
Solution Approach 2:
The recesses are designed in advance to prevent stress concentration before cracks can form. By creating geometric features that redistribute stresses beforehand, the design cushions the blade tips against the high cyclic stresses that occur during operation, preventing fatigue failure.
2Productivity
If blade tip clearances are reduced to improve compressor efficiency, then leakage decreases, but the risk of tip rubs and additional stress increases
Solution Approach 1:
The recesses can be designed with asymmetric geometries that account for the specific stress patterns and rub conditions experienced during operation. This asymmetric design allows optimal stress distribution while maintaining the desired tip clearance for efficiency.
Solution Approach 2:
The patent changes the geometric parameters of the blade tip by introducing recesses with specific dimensions, depths, and profiles. These parameter changes allow the blade to maintain smaller clearances for efficiency while the modified geometry prevents stress concentration during tip rub events.
3Reliability
If material is removed from blade tips to create recesses, then stress is reduced and rub tolerance increases, but the blade tip strength may be compromised
Solution Approach 1:
The recesses are designed with curved transitions rather than sharp corners, creating smooth stress flow paths. The curved geometries eliminate stress concentration points that would otherwise form at sharp edges, maintaining strength while still providing stress relief.
Solution Approach 2:
The recesses are designed to maintain adequate material thickness and structural integrity while still providing stress relief. The preliminary design ensures that material removal does not compromise overall blade tip strength by maintaining minimum thickness requirements and smooth transitions.
Data Source
AI summary
A compressor having a compressor blade with a blade tip portion configured to reduce stresses in the blade tip of the compressor blade is provided. The compressor blade includes a first and second faces extending to the blade tip portion. The blade tip portion includes a blade tip, a first recess extending between the first face and the blade tip, and a second recess extending between the second face and the blade tip.