Combustor Inner Skin Cooling Zone Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In small aero gas turbine engines, minimizing combustor wall cooling air while maintaining combustion efficiency is challenging, as excessive cooling air can interfere with the combustion process, leading to higher pollutant emissions and lower efficiency.
Innovation Solution
A combustor design with a primary zone cooled by a combination of impingement and convection cooling in the upstream half and a combination of impingement and effusion cooling in the downstream half, using heat transfer augmenters like pin fins in the upstream portion and effusion holes in the downstream portion, to optimize air usage and minimize interference with the combustion process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is supplied to combustor walls, then combustor wall cooling is improved, but combustion process is interfered with and pollutant emissions increase
Solution Approach 1:
The combustor wall is divided into multiple zones with different cooling requirements. The inner skin is segmented into regions with and without effusion holes, allowing differential cooling strategies in different spatial locations to optimize both cooling effectiveness and combustion protection.
Solution Approach 2:
Different cooling mechanisms are applied to different locations: effusion cooling is used in regions where combustion protection is needed, while impingement and convection cooling are used where maximum heat removal is required. This local differentiation resolves the contradiction between cooling effectiveness and combustion interference.
2Temperature
If effusion holes are provided in the inner skin, then cooling effectiveness is improved, but combustion quenching increases and efficiency decreases
Solution Approach 1:
Instead of providing effusion holes across the entire inner skin surface, effusion holes are provided only in specific downstream regions where they are most effective. The upstream region uses alternative cooling methods, creating a partial application strategy that balances cooling needs with combustion efficiency.
3Productivity
If cooling air amount is minimized, then combustion efficiency is improved, but combustor wall cooling is insufficient
Solution Approach 1:
The cooling strategy changes the parameters of cooling air usage by implementing multiple cooling mechanisms (impingement, convection, effusion) with different air consumption characteristics. This allows optimized air distribution that achieves adequate cooling with minimal total air consumption.
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 design reduces pollutant emissions and improves combustion efficiency by effectively managing cooling air distribution, allowing the existing cooling air to extract more heat before being used in the combustion chamber, while minimizing quenching and maintaining the integrity of the combustion process.
Implementation Method 1
heat transfer augmenters projecting from the inner skin into the air gap
Implementation Method 2
cooling down an inner skin of the combustor shell by using a combination of impingement and convection cooling
Implementation Method 3
effusion holes extending through the inner skin downstream of the heat transfer augmenters
Implementation Method 4
a combination of impingement and effusion cooling over a remaining downstream half of the primary zone
Implementation Method 5
the inner and outer skins defining an air gap therebetween
Data Source
AI summary
A gas turbine engine combustor has a shell defining a combustion chamber having a primary zone and a dilution zone downstream of the primary zone. The shell has an outer skin and an inner skin defining an air gap therebetween. The inner skin in the upstream portion of the primary zone is free from effusion holes and has heat transfer augmenters projecting from a back side thereof into the air gap. Effusion holes in the inner skin are only disposed downstream towards the tail end of the primary zone in order to delay the injection of any disruptive cooling air that could potentially interfere with the combustion process.