Combustor Liner Cooling via Non-Uniform Hole Density
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Solution Overview
Problem
Current cooling designs for gas turbine engine combustors are inadequate for small turbofan engines, as they do not scale linearly with size, leading to inefficiencies in cooling, fuel efficiency, and performance, particularly due to hot spots near diffuser pipes caused by small radial clearance.
Innovation Solution
The design incorporates an annular cooling band with a higher density of cooling holes in regions between diffuser pipes and a lower density in other areas, directing more cooling air to potential hot spots through a combination of first and second sets of cooling holes, ensuring efficient cooling without affecting combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If cooling holes are uniformly distributed across the combustor liner, then manufacturing is simplified, but cooling effectiveness is reduced in regions between diffuser pipes where hot spots occur
Solution Approach 1:
The patent applies local quality by varying the density of cooling holes across different regions of the combustor liner. Specifically, a first density of cooling holes is provided in first regions (between diffuser pipes) and a second density in second regions (aligned with diffuser pipes), where the first density is greater than the second density. This non-uniform distribution targets cooling effectiveness to where it is most needed while maintaining manufacturing feasibility.
2Temperature
If cooling air flow is increased to reduce hot spots, then cooling effectiveness improves, but fuel efficiency deteriorates due to higher cooling air consumption
Solution Approach 1:
The patent optimizes cooling air distribution by providing different cooling hole densities in different regions. The higher density in first regions (between diffuser pipes) targets hot spots more effectively, while the lower density in second regions (aligned with diffuser pipes) reduces unnecessary cooling air consumption. This localized approach improves cooling effectiveness where needed while minimizing overall cooling air usage, thereby preserving fuel efficiency.
3Volume of moving object
If combustor size is scaled down for small turbofan engines, then engine dimensions are reduced, but cooling performance deteriorates due to non-linear scaling of physical parameters
Solution Approach 1:
The patent addresses the scaling issue by implementing region-specific cooling hole densities that account for the non-linear scaling of thermal and fluid dynamics parameters. The higher density of cooling holes in first regions compensates for the reduced radial clearance and increased heat flux density in scaled-down combustors, maintaining cooling performance despite the overall size reduction.
Solution Approach 2:
The patent changes the parameter of cooling hole density to optimize cooling performance in scaled-down combustors. By varying the density parameter across different regions and adjusting the overall cooling hole pattern, the design compensates for the non-linear scaling effects on thermal and fluid dynamics, maintaining effective cooling in the smaller combustor configuration.
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 approach enhances cooling effectiveness, reduces hot spots, and maintains combustion efficiency and durability, addressing the limitations of scaling down larger combustor designs for small engines.
Implementation Method 1
Cooling of combustor walls is typically achieved by directing cooling air through holes in the combustor wall to provide effusion and/or film cooling
Implementation Method 2
Cooling of combustor walls is typically achieved by directing cooling air through holes in the combustor wall to provide effusion and/or film cooling
Implementation Method 3
supplied with compressed air from a compressor via a plurality of diffuser pipes in fluid flow communication therewith
Data Source
AI summary
A gas turbine engine combustor liner having a plurality of holes defined therein for directing air into the combustion chamber. The plurality of holes provide a greater cooling air flow in regions intermediate each diffuser pipe than in other areas of the combustor liner.