U-Shaped Combustor Liner Cooling Channels
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Solution Overview
Problem
Gas turbine engine combustors face challenges in reducing NOx emissions while maintaining effective cooling, as aggressive tapering in convergent combustion chamber designs can lead to entrainment of cooling flow, affecting local chemistry and increasing NOx formation.
Innovation Solution
A combustor design featuring a U-shaped channel with impingement and effusion holes, along with accelerating and divergent channels, and turbulence-inducing features like trip strips and pedestals, to manage cooling air flow and reduce its interaction with the fuel-rich zone, thereby controlling NOx formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aggressive tapering is used in the convergent combustion chamber section to increase combustion flow velocity and reduce residence time, then NOx formation is reduced, but cooling flow is entrained in the outer recirculation zone, affecting local chemistry and increasing flame temperatures and NOx formation
Solution Approach 1:
The cooling air flow path is segmented into distinct regions: a first region with a first cross-sectional area and a second region with a second cross-sectional area. This segmentation allows independent control of cooling air flow characteristics in different zones, preventing entrainment in the recirculation region while maintaining effective cooling in the combustion chamber.
Solution Approach 2:
Different regions of the combustor are provided with different cooling air flow characteristics. The first region has different flow properties than the second region, allowing localized optimization: high velocity flow in the combustion chamber for rapid combustion while controlled flow in the recirculation zone to prevent cooling air entrainment and maintain stable flame temperatures.
2Reliability
If cooling air flow is increased to enhance serviceable life of the engine, then component cooling is improved, but interaction with the fuel-rich zone increases, affecting local chemistry and NOx formation
Solution Approach 1:
The cooling air flow path is divided into multiple regions with different cross-sectional areas, allowing the cooling air to be directed away from the fuel-rich zone while still providing adequate cooling to the combustor liner. This segmentation prevents harmful chemical interactions while maintaining cooling effectiveness.
Solution Approach 2:
The varying cross-sectional areas of the cooling air flow path act as intermediaries that control and direct the cooling air flow. These geometric features mediate between the cooling requirement and the need to prevent interaction with the fuel-rich zone, creating an optimal flow path that achieves both cooling and chemical stability.
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 effectively reduces NOx production by optimizing cooling air flow, maintaining adequate cooling of the combustor liner, and preventing cooling air from interacting with the fuel-rich zone, thus lowering combustion chamber temperatures and emissions.
Implementation Method 1
Cooling air is forced through these flow cavities and into the combustion chamber, creating a cooling film on hot surfaces of the liners
Implementation Method 2
creating a cooling film on hot surfaces of the liners
Implementation Method 3
a U-shaped channel defined between the shell and the liner and defined in part by the wall, the channel having upstream and downstream ends both adjacent the first partition and separated by the wall; and wherein the impingement hole communicates with the upstream end and the effusion hole communicates with the downstream end
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A combustor having U-shaped cooling channels is disclosed. The combustor may include a shell having an impingement hole, a liner spaced from the shell and having an effusion hole; a first partition spanning between the shell and the liner, a second partition spaced from the first partition and spanning between the shell and the liner; and a U-shaped channel defined between the shell and the liner and defined in part by the wall, the channel having upstream and downstream ends both adjacent the first partition and separated by the wall, wherein the impingement hole communicates with the upstream end and the effusion hole communicates with the downstream end.