Gas Turbine Combustor Purge Air Soot Prevention
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Solution Overview
Problem
In gas turbine combustors, an annular space where the air-fuel mixture becomes stagnant leads to soot deposition, potentially damaging the guide member or heat shield due to heating by combustion gases.
Innovation Solution
Introducing compressed air through purge holes between the guide member and heat shield, guiding it obliquely outward to prevent soot deposition, while ensuring proper flame stabilization and suppressing fuel diffusion to maintain combustion performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an annular space is formed by the guide member and heat shield in the combustor, then the structural support and heat protection are improved, but soot deposition occurs on the guide member and heat shield due to stagnant air-fuel mixture
Solution Approach 1:
The patent extracts the harmful stagnant air-fuel mixture from the annular space by introducing purge air flow through the guide member. This creates a positive pressure zone that actively pushes the air-fuel mixture away from the guide member and heat shield surfaces, preventing soot deposition while maintaining the structural integrity of the annular space configuration
Solution Approach 2:
The patent applies pneumatic principles by using compressed purge air introduced through the guide member to create a pressurized flow field in the annular space. This pneumatic action generates outward radial flow that prevents soot accumulation on critical components, solving the deposition problem without compromising the structural support function
2Object-affected harmful factors
If purge air is introduced through the guide member to prevent soot deposition, then soot accumulation is reduced, but the complexity of the guide member structure increases
Solution Approach 1:
The guide member is designed with multiple purge air holes that allow compressed air to pass through. This porous structure enables the guide member to serve dual functions: maintaining structural support while actively preventing soot deposition through the purging action. The holes are strategically positioned to create effective airflow patterns without significantly complicating the overall structure
Solution Approach 2:
The guide member is designed to perform multiple functions simultaneously: providing structural support in the annular space, guiding the air-fuel mixture flow, and preventing soot deposition through integrated purge air holes. This multi-functionality reduces the need for separate components, thereby minimizing overall system complexity while achieving soot prevention
3Object-affected harmful factors
If the air flow is guided obliquely outward in the annular space, then soot deposition is prevented, but the flame stabilization may be affected
Solution Approach 1:
The patent applies different flow characteristics to different regions: the purge air flows obliquely outward in the annular space to prevent soot deposition, while the main combustion flow maintains its axial direction for proper flame stabilization. This localized differentiation of flow qualities allows simultaneous achievement of soot prevention and stable combustion
Solution Approach 2:
The airflow is segmented into two distinct streams: the purge air introduced through the guide member that flows obliquely outward to clean the annular space, and the main combustion air that continues axially to support stable flame. This segmentation allows each flow to perform its specific function without interfering with the other, preventing soot while maintaining flame 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
Effectively prevents soot deposition on critical components, enhances flame stabilization, and maintains combustion efficiency by controlling the air-fuel mixture flow and reducing fuel droplet size, thereby improving overall combustion performance.
Implementation Method 1
the air introduced through the purge hole is supplied to the space between the guide member and the cylindrical portion, the fuel, the air-fuel mixture and the flame, which are going to enter the space, can be pushed out
Implementation Method 2
since the air flowing into the space between the guide member and the cylindrical portion is guided by the guide section in the obliquely outward direction toward the downstream side, harmful effects which would be caused by the air flowing axially linearly, can be lessened
Implementation Method 3
the air-fuel mixture having flowed through the guide member and the air introduced through the purge hole, flow along the flare. This results in a back-flow zone having a proper speed component in a center axis portion. Thus, good flame stabilizing performance can be ensured
Implementation Method 4
the air introduced through the purge hole suppresses the air-fuel mixture which has flowed through the guide member from diffusing radially outward in the combustor. This can prevent the fuel in the air-fuel mixture from adhering onto the heat shield and liquid droplets of the fuel from increasing in size
Data Source
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AI summary
A gas turbine combustor 1 of the present invention comprises a fuel injector 13 for injecting a fuel F toward a combustion chamber 11; a swirler 14 which takes-in compressed air CA generated in a compressor and swirl the compressed air CA, in the vicinity of the fuel injector 13; a tubular guide member 34 for guiding the compressed air CA taken-in from the swirler 14, to the combustion chamber 11; and a heat shield 23 having a cylindrical portion 23b located outward relative to the guide member 34; wherein the cylindrical portion 23b has a purge hole 40; and air is introduced through the purge hole 40 and is supplied to a space 39 formed between the guide member 34 and the cylindrical portion 23b.