Combustor Dome Cooling Holes for Hot Spot Prevention
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Solution Overview
Problem
Conventional gas turbine engine combustor designs face challenges in achieving a balance between stable combustion and cooling, particularly around fuel supply holes, due to the formation of hot spots caused by inclined cooling holes, which can complicate the structure and increase machining steps.
Innovation Solution
The design involves forming cooling holes in the dome part of the combustor with varying inclinations relative to a virtual boundary line, creating swirl flows around adjacent fuel supply holes to stabilize combustion and prevent hot spots, with the cooling holes' outlets inclined towards the fuel supply holes to enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling holes are inclined so that the outlet is far away from the fuel supply hole, then the cooling air layer can be formed on the inner surface of the wall part, but a hot spot occurs around the fuel supply hole degrading combustor durability
Solution Approach 1:
The patent applies local quality by differentiating the inclination directions of cooling holes based on their radial position relative to the axis. Cooling holes in the radially outward region are inclined toward the second fuel supply hole, while cooling holes in the radially inward region are inclined toward the first fuel supply hole. This localized differentiation ensures that each region provides cooling air to the appropriate fuel supply hole, preventing hot spots while maintaining stable combustion.
2Reliability
If cooling holes are inclined so that the outlet is closer to the fuel supply hole, then hot spot around the fuel supply hole is prevented, but hot spot occurs at a different place on the dome part surface
Solution Approach 1:
The patent divides the cooling hole region into two zones based on a virtual boundary line and assigns different inclination directions to each zone. This local differentiation ensures that cooling air is distributed evenly across the entire dome part surface, preventing hot spots in one location from simply moving to another location.
3Reliability
If a canopy with L-shaped cross section is added to cover the fuel supply hole outlet, then hot spot prevention is achieved, but the combustor wall part structure becomes complicated and machining steps increase
Solution Approach 1:
The patent extracts the complex canopy structure from the design and replaces it with a simpler inclination control of cooling holes. By adjusting the inclination directions of existing cooling holes based on their radial position, the patent achieves hot spot prevention without adding the L-shaped canopy structure, thereby reducing structural complexity and machining steps.
Solution Approach 2:
Instead of adding a canopy to direct cooling air toward the fuel supply hole, the patent inverts the approach by directing the cooling holes themselves to incline toward the fuel supply holes. This inversion eliminates the need for additional directing structures while achieving the same cooling effect.
4Ease of manufacture
If cooling holes are uniformly inclined in one direction, then manufacturing is simplified, but stable combustion cannot be achieved due to improper cooling air distribution
Solution Approach 1:
The patent applies local quality by differentiating the inclination directions of cooling holes based on their radial position relative to the axis. Cooling holes in the radially outward region are inclined toward the second fuel supply hole, while cooling holes in the radially inward region are inclined toward the first fuel supply hole. This localized differentiation ensures that each region provides cooling air to the appropriate fuel supply hole, preventing hot spots while maintaining stable combustion.
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 stabilizes combustion by generating directed swirl flows and prevents hot spots by ensuring effective cooling around the fuel supply holes, while maintaining a manageable structure and machining complexity.
Implementation Method 1
a thin air layer being formed on an inner surface of the wall part of the combustor using air that has been introduced via the cooling holes, thus carrying out cooling of the dome part
Implementation Method 2
by generating a swirl flow in one direction by means of air passing through the cooling holes in the region radially outward of virtual boundary line and by generating a swirl flow in another direction by means of air passing through the cooling holes in the region radially inward of virtual boundary line, to stabilize combustion of an air-fuel mixture
Data Source
AI summary
Formed in a wall part of a dome part of an annular combustor encircling an axis of a gas turbine engine are multiple fuel supply holes spaced at predetermined intervals in circumferential direction around the axis and many cooling holes extending through the wall part in direction inclined to a normal thereof. When two adjacent fuel supply holes are defined as first and second fuel supply holes, a virtual boundary line contacting an outer semi-circular portion, far from the axis, of the first fuel supply hole and an inner semi-circular portion, close to the axis, of the second fuel supply hole is set. The first cooling holes in region radially outward, relative to the axis, of the line are inclined toward the second fuel supply hole, and the second cooling holes in region radially inward, relative to the axis, of the line are inclined toward the first fuel supply hole.