Gas Turbine Wall Panel Coating to Reduce Thermal Fatigue Cracking
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Solution Overview
Problem
Float wall liners in gas turbine engines are prone to thermal mechanical fatigue cracking due to thermal gradients and stress concentrations, which degrade the coating and structural integrity.
Innovation Solution
A wall panel assembly with a variable thickness thermal barrier coating applied to the liner panel, varying in thickness based on a ramp, sinusoidal, or arbitrary function to control temperature gradients and reduce thermal stresses, combined with cooling air impingement to manage thermal loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a float wall liner with coating is used to provide thermal protection, then thermal protection is achieved, but thermal mechanical fatigue cracking occurs due to thermal gradients and stress concentrations
Solution Approach 1:
The patent applies a variable thickness coating where the coating thickness varies axially along the liner. The coating is thicker at regions experiencing higher thermal gradients and stress concentrations, and thinner at regions with lower thermal loads. This non-uniform coating distribution provides enhanced thermal protection precisely where needed while reducing overall coating mass and minimizing thermal mechanical fatigue cracking.
Solution Approach 2:
The patent changes the physical parameter of coating thickness from a constant value to a variable value that changes axially along the liner length. This parameter variation allows the coating to adapt to different thermal and mechanical conditions at different axial positions, optimizing both thermal protection and fatigue resistance.
2Ease of manufacture
If a uniform thickness coating is applied to the liner panel, then manufacturing is simplified, but thermal gradients and stress concentrations cause fatigue cracking
Solution Approach 1:
The patent implements a coating with locally optimized thickness where the coating thickness varies axially along the liner. This local variation in coating quality provides enhanced thermal protection and fatigue resistance at high-stress regions while maintaining manufacturability through controlled deposition processes.
Solution Approach 2:
The patent transitions from a static, uniform coating thickness to a dynamic, variable thickness coating that adapts to the thermal and mechanical conditions at different axial positions. This dynamic coating design allows the system to better withstand thermal mechanical fatigue while remaining manufacturable.
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
The solution enhances the durability and service life of the combustor section by minimizing thermal mechanical fatigue cracking, reducing overhaul and repair costs, and maintaining isothermal conditions.
Implementation Method 1
A thermal barrier coating may be applied to the liner panel. The coating may have a variable nominal overall thickness distribution
Implementation Method 2
cooling air impingement to manage thermal loads
Data Source
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AI summary
A wall panel assembly (22) includes a first liner panel (50) and a coating (56). The first liner panel has a first liner panel inner surface (70) and a first liner panel outer surface (72) each axially extending between a first liner panel first end (80) and a first liner panel second end (82). The coating (56) is disposed on at least one of the first liner panel inner surface and the first liner panel outer surface. The coating has an overall thickness (t0) that varies axially between the first liner panel first end and the first liner panel second end.