Sealing Clip for Combustor Heat Shield Gap Reduction
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Solution Overview
Problem
In gas turbine engines, coolant leakage occurs between the combustor heat shields and the combustor shell due to manufacturing tolerances, leading to reduced combustion efficiency and increased emissions, which is more pronounced in smaller engines where the leakage is proportionally greater.
Innovation Solution
A sealing clip is used to locally deform the combustor liner, applying pressure over the heat shield rail to reduce leakage gaps by engaging with existing bolts and distributing force uniformly along the rail, thereby sealing the gap between the heat shield and the liner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coolant flow is increased to seal the gap between heat shield and combustor liner, then sealing effectiveness improves, but combustion efficiency decreases and emissions increase
Solution Approach 1:
A sealing clip is introduced as an intermediary component between the heat shield rail and combustor liner. The clip applies localized mechanical pressure to close the gap, eliminating the need for additional coolant flow to achieve sealing. This mediator transfers the sealing function from a fluid-based solution (coolant leakage) to a solid-based solution (mechanical compression), thereby improving sealing effectiveness without compromising combustion efficiency.
Solution Approach 2:
The sealing mechanism transitions from relying on coolant pressure differential to applying mechanical contact pressure through the sealing clip. By changing the sealing parameter from fluid pressure to solid contact force, the system achieves effective sealing with minimal coolant flow, thus resolving the contradiction between sealing effectiveness and combustion efficiency.
2Reliability
If manufacturing tolerances are tightened to eliminate leakage gaps, then sealing effectiveness improves, but manufacturing complexity and cost increase
Solution Approach 1:
Instead of requiring uniform tight tolerances across the entire heat shield and liner assembly, the sealing clip applies localized compression only at the specific gap location between the rail and liner. This allows manufacturing with standard tolerances elsewhere while achieving effective sealing at the critical interface, thereby reducing manufacturing complexity while maintaining sealing effectiveness.
Solution Approach 2:
The sealing clip is pre-formed with the appropriate compression characteristics and is then installed onto the heat shield rail before final assembly. This preliminary preparation allows the sealing function to be integrated without requiring complex post-assembly adjustments or specialized manufacturing processes, thus reducing overall device complexity.
3Productivity
If coolant flow is minimized to improve combustion efficiency, then combustion efficiency improves, but sealing effectiveness deteriorates
Solution Approach 1:
The sealing clip serves as a mechanical intermediary that provides the sealing function independently of coolant flow. By introducing this solid-based sealing mechanism, the system can minimize coolant flow to improve combustion efficiency while the clip maintains effective sealing through direct mechanical contact, thus resolving the contradiction between these two parameters.
4Reliability
If sealing pressure is applied to close the gap, then sealing effectiveness improves, but risk of blocking impingement holes increases
Solution Approach 1:
The sealing clip is designed to apply compression force in a highly localized manner directly at the gap between the rail and liner. The contact area is precisely controlled to match only the sealing interface geometry, ensuring that pressure is concentrated where needed while leaving the impingement holes and other surrounding areas unaffected. This localized approach achieves effective sealing without the risk of blocking critical flow paths.
Solution Approach 2:
The sealing function is segmented into a dedicated component (the sealing clip) that is separate from the main heat shield and liner structures. This segmentation allows the sealing clip to be independently designed and optimized to apply pressure only where required, preventing unintended effects on impingement holes while maintaining effective sealing at the target interface.
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 method effectively reduces airflow leakage without blocking impingement holes, improving combustion efficiency and reducing emissions by minimizing coolant usage and enhancing the utilization of cooling air flow.
Implementation Method 1
locally deforming the combustor liner in sealing engagement with the rail by applying a pressure on the outer surface of the combustor liner over the rail of the heat shield
Data Source
AI summary
A method and an apparatus for reducing airflow leakage between a combustor liner and a rail of a heat shield mounted to an inner surface of the combustor liner. The method comprises locally deforming the combustor liner in sealing engagement with the rail by applying a pressure on the outer surface of the combustor liner over the rail of the heat shield. A tool, such as a sealing clip, may be mounted in pressing engagement with the outer surface of the combustor liner to apply forces locally on the liner over the rail of the heat shield.