Gas Turbine Combustor Bulkhead Impingement Cooling Rings
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Solution Overview
Problem
Modern heat shield panels in gas turbine combustors lack sufficient effusion cooling holes, leading to increased temperatures due to hot gas recirculation and non-uniform cooling, resulting in elevated temperatures and debris accumulation in low-flow cavity regions.
Innovation Solution
The implementation of a configuration with impingement cooling rings and rings having a plurality of impingement cooling holes oriented normal to the bulkhead, which direct cooling air to impinge on the heat shield panel, providing more uniform cooling and reducing dead spots and debris accumulation by varying the radial spacing and number of cooling holes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat shield panels have large amounts of effusion holes for cooling, then cooling effectiveness is improved, but flame anchoring within the combustor deteriorates
Solution Approach 1:
The bulkhead is segmented into multiple cooling zones with impingement cooling rings at different locations, each targeting specific heat shield regions. This segmentation allows cooling to be distributed effectively without requiring numerous effusion holes in the heat shield itself, thus maintaining flame anchoring while achieving adequate cooling through impingement from the bulkhead side
Solution Approach 2:
The impingement cooling rings act as intermediaries between the cooling air source and the heat shield panel. Instead of directly cooling the heat shield through effusion holes, the cooling air is first directed through the bulkhead impingement rings to impinge on the heat shield's outer surface, providing indirect cooling that preserves flame anchoring
2Temperature
If impingement cooling holes are biased towards known hot spots, then localized cooling effectiveness is improved, but uniformity of cooling flow deteriorates
Solution Approach 1:
Different impingement cooling rings are designed with varying hole densities and patterns tailored to local thermal conditions. Rings closer to the combustion chamber have different characteristics than those farther away, allowing each zone to be optimized for its specific thermal environment while maintaining overall flow uniformity
Solution Approach 2:
The cooling approach transitions from a single-plane effusion hole pattern to a multi-dimensional impingement cooling system with rings positioned at different axial locations and orientations. This dimensional expansion allows cooling air to approach the heat shield from multiple directions, improving both localized effectiveness and overall uniformity
3Temperature
If conventional impingement cooling configuration is used, then cooling air is directed to hot spots, but dead spots with elevated temperatures and debris accumulation occur
Solution Approach 1:
The impingement cooling rings employ asymmetric hole patterns and varying radial spacing rather than uniform symmetric distributions. This asymmetry creates more complex, turbulent cooling air flows that better penetrate into cavity regions and prevent dead spots where debris would otherwise accumulate, while still targeting hot spot areas
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 enhances the uniformity of cooling flow and reduces temperature variations and debris accumulation, improving heat shield panel cooling efficiency and maintaining cleanliness within the impingement cooling chamber.
Implementation Method 1
relatively cool air from outside of the combustor is used to cool the bulkhead side of the heat shield panels
Implementation Method 2
This cooling air may then be directed into the combustion chamber through effusion holes in the heat shield
Data Source
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AI summary
A combustor (50) for a gas turbine engine includes a combustion chamber (56) defined between an inner shell (54) and an outer shell (52). The combustor (50) further includes a bulkhead (68) extending between the inner shell (54) and the outer shell (52). The bulkhead (68) includes a plurality of impingement cooling rings. Each impingement cooling ring of the plurality of impingement cooling rings includes a plurality of impingement cooling holes extending through the bulkhead. The combustor (50) further includes a heat shield panel (82) mounted to the bulkhead (68) so as to define an impingement cooling chamber (104) between the bulkhead (68) and the heat shield panel (82). The heat shield panel (82) further includes a radial portion between a perimeter and an opening, with respect to an opening center axis (100), which is free of penetrations. The plurality of impingement cooling holes of each of the plurality of impingement cooling rings are directed toward the radial portion of the heat shield panel (82).