Axial Compressor Groove Casing for Stall Margin
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Solution Overview
Problem
The stability of the compression system in gas turbine engines is limited by tip leakage flow, which can lead to stall conditions, and previous attempts to improve stability through casing treatments have resulted in reduced engine efficiency.
Innovation Solution
A method of manufacturing a compressor with selectively positioned and shaped circumferential grooves in the compressor case to manage tip leakage flow, including forward, intermediate, and aft grooves, optimized using computational fluid dynamics to enhance stall margin and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If casing treatments are applied to improve compressor stability, then stall margin is increased, but engine efficiency is reduced
Solution Approach 1:
The patent applies different groove configurations at different axial locations (forward, intermediate, and aft grooves) to address local flow characteristics. Each groove section is optimized for its specific position to manage tip leakage flow locally while minimizing overall efficiency loss. This localized approach allows stability improvement without uniform efficiency penalty across the entire compressor stage.
Solution Approach 2:
The circumferential grooves are divided into multiple discrete sections (forward groove, intermediate groove, aft groove) rather than a continuous treatment. This segmentation allows each groove section to perform a specific function in managing different aspects of tip leakage flow, enabling fine-tuned control over flow characteristics to balance stability and efficiency.
2Reliability
If tip clearance is reduced to improve stability, then stall margin increases, but manufacturing complexity and cost increase
Solution Approach 1:
The circumferential grooves act as an intermediary structure between the airfoil tip and compressor case. Rather than directly reducing the tip clearance gap, the grooves modify the flow field in the clearance region to achieve stability improvement. This indirect approach avoids the manufacturing complexity and cost associated with tighter clearances while still achieving the desired stability enhancement.
3Reliability
If circumferential grooves are added to manage tip leakage flow, then stall margin is improved, but device complexity increases
Solution Approach 1:
The groove treatment is applied locally at specific axial positions rather than as a continuous circumferential feature. This localized application minimizes the overall complexity addition to the compressor case while concentrating the flow control effect where it is most needed to improve stall margin.
Solution Approach 2:
The grooves are segmented into discrete sections (forward, intermediate, aft) with specific spacing and dimensions. This segmentation allows each groove to perform a targeted flow control function, achieving improved stall margin through distributed flow management rather than a single complex continuous feature.
Data Source
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AI summary
A compressor (24) is provided. The compressor (24) includes a rotating member configured to rotate about an axis (A-A') and a static member (102) radially adjacent the rotating member with a clearance between the static member (102) and the rotating member. A first groove (104) is disposed circumferentially about the static member (102) and radially adjacent the rotating member. A second groove (106) is disposed circumferentially about the static member (102) and a first axial distance (L3) aft of the first groove (104). A third groove (108) is disposed circumferentially about the static member (102) and a second distance (L5) aft of the second groove (106), wherein the first distance (L3) is different from the second distance (L5).