Gas Turbine Combustor Liner Cooling With Raised Wall Air Holes
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Solution Overview
Problem
Existing combustors for gas turbine engines face challenges in effectively decelerating cooling air flow through cooling air holes without increasing the weight of the combustor, which is necessary for efficient cooling of the liner while maintaining structural integrity.
Innovation Solution
The design incorporates raised wall portions with thick wall portions at the ends of cooling air holes and flared portions that progressively increase in cross-sectional area, along with inclined and cylindrical wall portions to guide the cooling air flow, thereby increasing passage length and reducing velocity without increasing the combustor's weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the passage length of cooling air holes is increased to decelerate cooling air flow, then cooling efficiency is improved, but the wall thickness of the liner must be increased which causes weight increase
Solution Approach 1:
The invention introduces raised wall portions that extend in the circumferential direction, creating a third dimension (circumferential extension) to increase the passage length of cooling air holes without increasing the axial length or radial thickness of the liner. This allows the cooling air to travel a longer path through the thick wall portions, effectively decelerating the flow while avoiding weight increase from increased wall thickness.
2Speed
If the cross-sectional area of cooling air holes is increased to reduce flow velocity, then cooling efficiency is improved, but the structural integrity of the liner is compromised
Solution Approach 1:
Instead of increasing the cross-sectional area of cooling air holes (which would compromise structural integrity), the invention extends the passage length in the circumferential direction through raised wall portions. This allows velocity reduction through increased path length rather than increased area, maintaining the liner's structural strength while achieving effective cooling air deceleration.
3Length of stationary object
If the wall thickness of the liner is increased to provide longer cooling air holes, then cooling efficiency is improved, but the weight of the combustor increases
Solution Approach 1:
The invention increases the passage length of cooling air holes by extending them in the circumferential direction through raised wall portions, rather than increasing the radial wall thickness. This dimensional change allows longer cooling passages without increasing the overall size or weight of the combustor, as the extended path is achieved through circumferential arrangement rather than radial thickening.
Solution Approach 2:
The liner is segmented into multiple raised wall portions with cooling air holes distributed across them. This segmentation allows the cooling air to traverse through multiple sections (first thick wall portions and second thick wall portions) in sequence, effectively increasing the total passage length without requiring a single thick wall structure that would increase weight.
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 decelerates cooling air flow, minimizes weight increase, and enhances the cooling efficiency of the liner, improving the durability and performance of the combustor by reducing the likelihood of air separation and allowing higher combustion gas temperatures, thus increasing the compressor's pressure ratio and engine efficiency.
Implementation Method 1
the flared portions progressively increase in cross-sectional area with respect to the flowing direction of the cooling air, the cooling air flowing through the cooling air holes into the combustion chamber is effectively decelerated
Implementation Method 2
the film of air formed along the inner surface of the liner prevents the liner from being excessively heated by the combustion gas in the combustor
Implementation Method 3
the passage length of the cooling air holes is increased so that the cooling air flowing through the cooling air holes into the combustion chamber is effectively decelerated
Data Source
AI summary
A combustor for a gas turbine engine that is placed in a compressed air chamber of the gas turbine engine to generate combustion gas, the combustor being provided with a liner that defines a combustion chamber therein around a prescribed central axis, the liner comprising a plurality of raised wall portions that extends in a circumferential direction at an angle with respect to the central axis and are arranged at predetermined intervals along the central axis, a plurality of cooling air holes passed through the raised wall portions, and thick wall portions provided circumferentially in parts of the raised wall portions at ends of the cooling air holes.