Combustor Dilution Hole Cooling via Sub-Chamber Merging
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Solution Overview
Problem
The areas surrounding dilution holes in gas turbine combustors experience hot spots due to inadequate cooling, leading to a need for an improved cooling scheme to manage the high heat load and secondary flow structures.
Innovation Solution
A combustor design featuring a heat shield with an air gap and a sub-chamber system, where a peripheral dilution flow merges with a core dilution flow to enhance cooling, utilizing impingement holes and effusion holes to direct cooling air effectively around the dilution holes, creating a more efficient cooling mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional cooling schemes with separate impingement jets and dilution flow are used, then the cooling system is simple in structure, but hot spots develop in areas surrounding the dilution holes due to inadequate cooling
Solution Approach 1:
The patent combines the previously separate impingement cooling flow and dilution flow into a single integrated flow path. Cooling air is directed through the air gap and merged with dilution air in a sub-chamber, creating a unified flow that simultaneously cools the heat shield and provides dilution, thereby eliminating hot spots while maintaining structural simplicity
Solution Approach 2:
The integrated flow system performs multiple functions: it cools the heat shield through impingement, provides dilution for the combustion chamber, and cools the area surrounding the dilution holes. This multi-functional approach addresses multiple thermal management needs with a single system, improving temperature distribution without proportionally increasing complexity
2Temperature
If the dilution flow is taken directly from the external air supply cavity through dilution holes, then the dilution flow path is short and simple, but the areas surrounding the dilution holes experience hot spots due to lack of cooling air
Solution Approach 1:
The patent introduces an intermediary sub-chamber and air gap region between the external air supply cavity and the combustion chamber. This intermediary space allows cooling air to be conditioned and merged with dilution air before entering the combustion chamber, providing enhanced cooling to the area surrounding the dilution holes while managing the flow path length through strategic positioning
3Temperature
If impingement holes and effusion holes are used to cool the heat shield, then the heat shield cooling is effective, but the cooling air is independent and separate from the dilution flow, creating inadequate cooling in peripheral areas
Solution Approach 1:
The patent merges the impingement cooling flow and dilution flow into a single integrated system. The flow through the air gap and sub-chamber combines both cooling and dilution functions, eliminating the need for completely separate flow systems while maintaining effective heat shield cooling and adding peripheral area cooling capability
Data Source
AI summary
A combustor for a gas turbine engine including a combustor shell, a heat shield mounted to the combustor shell spaced-apart from the combustor shell to define an air gap therebetween, a core dilution passageway extending through the combustor shell and the heat shield, and a sub-chamber disposed within the air gap in fluid communication with the core dilution passageway. The sub-chamber is separated from a remainder of the air gap by at least one intermediate rail projecting across the air gap and forming an outer boundary of a peripheral area of the core dilution passageway. Impingement holes are formed through the combustor shell and in fluid communication with the sub-chamber. A method of cooling an area surrounding a dilution hole in a combustor is also presented.