Heat Shield Labyrinth Seal for Combustor Leakage Control
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Solution Overview
Problem
In gas turbine engines, excessive leakage of compressed cooling air through gaps between heat shields and the combustor shell leads to energy loss and reduced efficiency, as the existing sealing methods fail to adequately control the flow of cooling air.
Innovation Solution
A seal configuration featuring non-linear leakage paths created by circumferential projections on the combustor shell and heat shields, utilizing advanced manufacturing techniques like direct metal laser sintering and metal injection molding to produce precise sealing surfaces, such as castellated or serrated ridges, which impede cooling air leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional sealing methods are used between heat shields and combustor shell, then the structure is simple and easy to manufacture, but excessive leakage of cooling air occurs leading to energy loss
Solution Approach 1:
The sealing surface is divided into multiple segments with alternating protrusions and recesses, creating a labyrinthine path that increases leakage resistance without requiring a completely complex seal structure. The combustor shell has circumferential protrusions while the heat shield has corresponding recesses, segmenting the sealing interface into multiple zones.
Solution Approach 2:
The sealing approach transitions from a simple linear contact seal to a multi-dimensional labyrinthine path with alternating radial and axial components. The cooling air must navigate through alternating protrusions and recesses in both radial and axial directions, effectively adding dimensional complexity to the leakage path without dramatically increasing overall structural complexity.
2Productivity
If simple gap sealing is used between heat shields and combustor shell, then manufacturing is easy, but cooling air flows uncontrolled through gaps reducing engine efficiency
Solution Approach 1:
The sealing interface is segmented into multiple protrusion-recess pairs around the circumferential direction, creating multiple barriers to air flow. This segmentation allows each individual protrusion or recess to be manufactured with standard tolerances while the cumulative effect of multiple segments achieves the required overall sealing performance.
Solution Approach 2:
The sealing surfaces incorporate curved or rounded profiles on the protrusions and recesses rather than sharp edges, which helps distribute contact pressures and accommodates manufacturing variations. The curved surfaces provide more forgiving tolerance zones while still maintaining effective sealing when properly assembled.
3Area of stationary object
If multiple heat shield panels with edge joints are used, then the heat shield can cover the combustor shell effectively, but gaps between panels and combustor wall allow cooling air leakage
Solution Approach 1:
The sealing solution applies local quality variations at the interface between heat shield panels and combustor shell. Specific regions (protrusions and recesses) have enhanced sealing properties while the rest of the heat shield panels maintain their primary thermal protection function. This localized sealing approach addresses leakage at critical joints without compromising overall heat shield performance.
Solution Approach 2:
The circumferential sealing path is divided into multiple segments corresponding to the edges of individual heat shield panels. Each panel edge creates a sealing segment with its own protrusion-recess configuration, allowing the total sealing effect to be achieved through the cumulative action of multiple discrete segments rather than requiring a single continuous seal.
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 proposed seal configuration reduces cooling air leakage by up to 50% compared to traditional methods, enhancing engine efficiency by minimizing uncontrolled air flow and maintaining effective cooling.
Implementation Method 1
the first and second sealing surfaces respectively include first and second circumferential projections, which jointly define a continuous non-linear leakage path along a circumferential segment of the combustor shell
Data Source
AI summary
A seal for sealing a combustor heat shield against an interior surface of a combustor shell, the seal comprising: a first sealing surface on the interior surface of the combustor shell; and a second sealing surface on a rail on an edge of a heat shield, wherein each of the first and second sealing surfaces include first and second projections defining a non-linear leakage path between the projections.