Compressor Flange Leak-Resistant Plates for Cyclic Life
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Solution Overview
Problem
Gas turbine compressor casings face challenges in achieving high cyclic life and low Specific Fuel Consumption (SFC) due to the trade-off between reducing hoop stress and leakage, where stress-relief holes improve cyclic life but increase leakage, and increasing bolt density reduces leakage but increases weight and SFC.
Innovation Solution
The compressor casing design incorporates a first and second annular casing segment with radially-extending flanges, stress-relief holes, and annular leak-resistant plates aligned with mounting holes to seal stress-relief holes, preventing leakage while maintaining cyclic life and low SFC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If stress-relief holes are introduced into the radially-extending flanges to reduce hoop stress, then the cyclic life of the bolt holes and casing joints is improved, but leakage through flange mating/seating surfaces increases
Solution Approach 1:
The flange is segmented by introducing stress-relief holes to divide the continuous material structure, reducing hoop stress concentration and improving cyclic life of the casing joints while maintaining structural integrity through strategic hole placement
Solution Approach 2:
A leak-resistant plate is introduced as an intermediary component between the flange mating surfaces. This plate covers the stress-relief holes and prevents gas leakage through the flange joint, while allowing the stress-relief holes to remain in place for hoop stress reduction
2Duration of action of stationary object
If the density or amounts of bolt holes are increased to reduce hoop stress and leakage, then the cyclic life is improved and leakage is reduced, but the weight increases
Solution Approach 1:
Instead of adding more bolt holes to the flange, the solution segments the stress management function by introducing stress-relief holes that are specifically designed to reduce hoop stress without compromising structural strength, thereby avoiding the need for additional bolts and associated weight
Data Source
AI summary
Various embodiments include a compressor casing and a method of assembly. The compressor casing comprises a first and an adjacent, second annular casing segments each comprising an annular radially-extending flange with mounting holes; at least one annular recess disposed on at least one annular side mating face of the adjacent flanges of the adjacent segments; at least one set of stress-relief holes disposed through at least one flange of the adjacent segments; and at least one annular leak-resistant plate disposed within the at least one annular recess having at least a third set of mounting holes. All sets of mounting holes are substantially aligned with each other and receive a plurality of respective fasteners, and the at least one annular plate is clamped between the adjacent segments and seals the at least one set of stress-relief holes for preventing leakage therethrough.