TEC Shroud Recess Geometry for Strut Stress and Fatigue Life
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Solution Overview
Problem
Gas turbine components, particularly turbine exhaust casings, face extreme temperature differentials and cyclical loads that lead to thermally induced stresses and reduced fatigue life, necessitating a design that balances high-temperature resistance with aerodynamic performance.
Innovation Solution
The design incorporates radially extending struts with recesses in the channel surface at the intersection points with the hub and shroud, minimizing stress and allowing for a lighter, optimized strut configuration that maintains aerodynamic flow and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the strut is designed with a standard smooth channel surface at the intersection points, then the aerodynamic flow is maintained, but the stress concentration occurs at the strut-shroud interface reducing fatigue life
Solution Approach 1:
The patent applies a recess feature locally at the strut-shroud intersection points where stress concentration occurs, while maintaining the smooth aerodynamic surface elsewhere in the channel. This localized geometric modification reduces stress concentration at the critical interface without disrupting the overall aerodynamic flow path.
2Reliability
If the strut configuration is optimized to reduce stress at the interface, then the fatigue life is enhanced, but the weight of the TEC increases
Solution Approach 1:
The patent modifies the geometric parameters of the channel surface by introducing a recess at the strut intersection points. This parameter change allows for stress reduction and fatigue life enhancement while the recess is designed with controlled dimensions to minimize material removal and weight increase.
3Reliability
If the recess is made deeper to further reduce stress, then the fatigue life is improved, but the aerodynamic performance deteriorates due to flow disruption
Solution Approach 1:
The recess is designed with specific dimensional parameters that balance stress reduction and aerodynamic performance. The depth, width, and positioning of the recess are optimized to provide sufficient stress relief at the strut interface while maintaining acceptable aerodynamic flow characteristics in the channel.
Data Source
AI summary
The invention concerns a turbine exhaust casing (TEC) for a gas turbine engine in which portions of the inner surface of the casing against which exhaust gas flows are provided with recesses extending into the surfaces. The recesses are positioned proximate to the leading edges of struts which extend between an outer shroud and inner hub of the casing.