Annular Heat Shield Segments with Offset Overlap Joints
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Solution Overview
Problem
In gas turbine engines, the thermal growth difference between combustor liners and heat shield panels creates gaps, leading to cooling air escape and efficiency loss due to the separation of heat shields from the combustor liner.
Innovation Solution
An annular heat shield arrangement with circumferentially distributed segments featuring complementary overlap joint portions that form an overlap joint when paired, allowing for thermal expansion without rigid interconnections, thereby maintaining a sealed assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat shield panels are attached to the combustor liner, then thermal protection is provided, but gaps form due to thermal growth difference causing cooling air leakage
Solution Approach 1:
The heat shield assembly is divided into multiple segments that can independently expand and contract. Each segment is separated by gaps that allow for thermal growth while maintaining overall coverage. This segmentation resolves the contradiction by enabling thermal protection through multiple smaller units that can accommodate differential thermal expansion without creating continuous leakage paths.
Solution Approach 2:
The heat shield panels utilize flexible connection mechanisms and thin film structures that can deform and adapt to thermal expansion. The panels are designed with flexibility to maintain contact with the combustor liner while accommodating growth differences, preventing cooling air leakage without rigid constraints that would cause thermal stress.
2Loss of energy
If heat shield panels are rigidly connected to maintain sealing, then cooling air leakage is prevented, but thermal stress and deformation occur due to thermal growth difference
Solution Approach 1:
The heat shield assembly employs dynamic connection mechanisms that allow panels to move and adjust their positions in response to thermal expansion. The connections are designed to be flexible rather than rigid, enabling the structure to adapt to changing thermal conditions while maintaining sealing effectiveness and preventing excessive thermal stress accumulation.
Solution Approach 2:
The design incorporates expansion gaps and flexible connectors that anticipate and accommodate thermal growth before excessive stress develops. These pre-designed clearance spaces act as cushioning elements that absorb thermal expansion forces, preventing rigid contact and subsequent thermal stress damage while maintaining operational sealing.
3Strength
If heat shield panels are separated to accommodate thermal growth, then thermal stress is reduced, but cooling air escapes and efficiency is lost
Solution Approach 1:
The heat shield is divided into multiple segments with controlled gaps between them. This segmentation allows each segment to independently accommodate thermal growth, reducing thermal stress while the overall segmented structure maintains coverage and minimizes cooling air escape through the gaps.
Solution Approach 2:
Different regions of the heat shield assembly have different properties - some areas have tighter connections for sealing while others have larger gaps for thermal expansion. This local differentiation allows the structure to simultaneously reduce thermal stress in critical areas while maintaining efficiency in other regions by minimizing leakage paths.
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 effectively prevents cooling air leakage and maintains efficiency by allowing thermal expansion while keeping the heat shields securely attached to the combustor liner, enhancing the overall performance of the gas turbine engine.
Implementation Method 1
Due to a difference in thermal growth between the combustor liner and the heat shield panels, the heat shield panels may be separated by a gap
Data Source
AI summary
An annular heat shield arrangement for a combustor liner comprises annular heat shield assemblies. The annular heat shield assemblies include heat shield segments circumferentially distributed around an axis of the annular heat shield assembly. The heat shield segments extend from a first lateral edge face to a second lateral edge face, a first overlap joint portion being defined at the first lateral edge face, a second overlap joint portion being defined at the second lateral edge face. The first overlap joint portion and the second overlap joint portion are complementary to form an overlap joint when pairs of the heat shield segments are side by side in any one of the heat shield assemblies. An adjacent pair of the annular heat shield assemblies are connected to one another at an overlap between the pair, and wherein the overlap joints from a first of the annular heat shield assemblies of the pair are circumferentially offset from a second of the annular heat shield assemblies of the pair.