Gas Turbine Combustor Cavity Cover Welding Geometry
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Solution Overview
Problem
The structural material of a gas turbine combustor's burner experiences significant thermal stress due to the temperature difference between compressed air and fuel, which can lead to stress concentration at weld zones, particularly at cavity corners, potentially causing cracks and reducing the reliability of the burner.
Innovation Solution
The design incorporates an inner and outer cylinder configuration with a burner featuring a cavity formed by a groove and a cover with an L-shaped or U-shaped cross-section, where the cover is welded to the structural material, and the boundary between the cover and the groove is positioned away from the corner, reducing thermal stress on the weld zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cavity is formed with an inlay structure using a cover and structural material, then the cavity can be securely closed, but the L-shaped contact surfaces create stress concentration at corners when welded
Solution Approach 1:
The patent applies local quality by creating a recess in the cover that locally changes the geometry of the contact surface. This recess eliminates the L-shaped corner configuration at the critical weld zone, replacing it with a smoother transition that reduces stress concentration while maintaining the overall inlay closure structure.
Solution Approach 2:
The patent introduces curvature by forming a recess with a curved bottom surface in the cover. This curved geometry replaces the sharp L-shaped corner with a smooth transition, reducing stress concentration at the weld zone while maintaining the structural integrity of the inlay closure.
2Stress or pressure
If fuel is preheated before supply to the cavity, then thermal stress on the structural material is reduced, but additional facilities and energy are required
Solution Approach 1:
The patent converts the harmful thermal stress effect into a beneficial structural adaptation. Instead of trying to eliminate the temperature difference through fuel preheating, the design adapts the cavity structure with a recess and extended contact surface to accommodate and mitigate the thermal stress, turning the thermal challenge into a structural solution.
Solution Approach 2:
The cavity structure serves itself by incorporating the recess and extended contact surface directly into the cover and structural material design. This self-contained structural adaptation eliminates the need for external fuel preheating facilities, as the geometry itself mitigates the thermal stress problem.
3Strength
If the cover is welded to the structural material at L-shaped contact surfaces, then the cavity is securely fastened, but cracks can form at unwelded portions facing the cavity corner
Solution Approach 1:
The patent applies local quality by creating a recess that specifically modifies the geometry at the critical corner region where cracks typically form. This localized geometric change eliminates the L-shaped configuration at the vulnerable unwelded portion, reducing stress concentration and crack formation risk while maintaining overall weld strength.
Solution Approach 2:
The patent introduces curvature through the recess with a curved bottom surface, replacing the sharp L-shaped corner geometry with a smooth transition. This curved geometry at the weld zone eliminates stress concentration points where cracks would form, while the extended contact surface maintains adequate welding area for structural strength.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively reduces thermal stress on the weld zone, enhancing the reliability of the burner by dispersing stress and preventing crack formation, even without fuel preheating, thus improving the structural integrity and operational efficiency of the gas turbine combustor.
Implementation Method 1
The cover is joined by welding to the structural material
Implementation Method 2
the structural material is affected by thermal stress caused by the temperature difference between the fuel and the compressed air
Data Source
AI summary
The present invention reduces thermal stress that is applied to the weld zone of a cavity formed in the structural material of a burner. The burner includes the cavity distributing a fuel to fuel nozzles. The cavity is demarcated by a groove formed in the structural material of the burner so as to create a level difference at an opening, and a cover fitted into the level difference to close the groove. The cover is formed by a web covering the opening in the groove and a flange extending in the depth direction of the groove to be fitted into the level difference, and is joined by welding to the structural material in such a manner as to have an L-shaped cross-section. When viewed in a cross-section orthogonal to the groove, a cover-side inner surface that is an inner surface of the flange forming a lateral surface of the cavity is flush with a groove-side inner surface that is an inner surface of the groove forming a lateral surface of the cavity. The boundary between the cover-side inner surface and the groove-side inner surface is away from a first corner of the cavity sandwiched between the cover-side inner surface and the inner surface of the web forming a ceiling surface of the cavity.