Gas Turbine Combustor Fuel Diffusion Restraining Mechanism
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Solution Overview
Problem
Conventional combustors for gas turbine engines face challenges in maintaining stable ignition and flame holding performance under lower intensity combustion conditions due to excessive air supply from the pre-mixture combustion system, leading to potential flame failure and reduced combustion efficiency.
Innovation Solution
A combustor design incorporating a fuel diffusion restraining mechanism with an annular step member having a triangular longitudinal section, which separates the fuel stream from the inner circumferential face of the diffusion passage portion, preventing undue spreading and ensuring a fuel-rich region for diffusion combustion, while suppressing the diffusion of fuel and air mixing, thereby maintaining a suitable fuel concentration for stable combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a great amount of air is supplied from the pre-mixture supply portion into the diffusion combustion region during starting operation or lower intensity combustion, then the lean pre-mixture combustion system can reduce NOx generation, but the fuel concentration becomes significantly low leading to flame failure and deterioration of ignition performance and flame holding performance
Solution Approach 1:
The combustor is divided into distinct functional regions: a diffusion combustion region for stable ignition and flame holding, and a pre-mixture combustion region for NOx reduction. The fuel spray portion and pre-mixture supply portion are spatially segmented to operate independently in their respective zones, allowing each system to optimize its performance without interference.
Solution Approach 2:
Different combustion modes are applied to different spatial locations within the combustor. The diffusion combustion system operates in the central region where fuel concentration must be high for stable combustion, while the pre-mixture combustion system operates in the outer region where lean combustion is feasible. This local differentiation allows simultaneous achievement of flame stability and emissions control.
2Productivity
If the diffusion passage portion spreads the diffusion combustion region extensively, then combustion efficiency can be enhanced, but the fuel stream contacts the inner circumferential face causing undue spreading and reducing fuel concentration in critical regions
Solution Approach 1:
The guide skirt member acts as an intermediary structure between the diffusion passage portion and the pre-mixture supply portion. It redirects the fuel stream away from the inner circumferential face of the pre-mixture supply portion, preventing unwanted contact and maintaining proper fuel concentration distribution while still allowing the diffusion combustion region to spread for efficient 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
The solution enhances ignition performance, flame holding, and stability of combustion under lower intensity conditions by preventing flame failure and maintaining a stable fuel concentration in the diffusion combustion region, leading to improved combustion efficiency and reduced air interference.
Implementation Method 1
a fuel atomizing portion (81a), which is adapted to change the fuel into particles suitable for combustion by utilizing shearing force of air
Implementation Method 2
a diffusion passage portion (81b) disposed on the downstream side of the fuel atomizing portion (81a), adapted to diffuse the fuel and air at a speed suitable for the combustion
Data Source
Figure 1
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AI summary
The present invention provides a combustor of a gas turbine engine, including: a fuel spray portion (3) configured to spray a fuel so as to create a diffusion combustion region (50) in a combustion chamber (12), the fuel spray portion including a fuel atomizing portion (3a) configured to atomize the fuel, and a diffusion passage portion (3b) disposed downstream of the fuel atomizing portion, the diffusion passage portion having a spreading trumpet-like shape and being configured to diffuse the fuel and the air; a pre-mixture supply portion (4) configured to supply a pre-mixture gas including the fuel and an air so as to create a pre-mixture combustion region (51) in the combustion chamber, the pre-mixture supply portion being positioned concentrically with the fuel spray portion so as to surround the fuel spray portion; and fuel diffusion restraining member (43) disposed on an inner circumferential face of the diffusion passage portion for restraining a diffusion of an injected fuel by separating a stream of the injected fuel away from the inner circumferential face.