Hydrogen Combustor Air-Fuel Mixer for Burn-Back Control
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Solution Overview
Problem
The use of hydrogen as a fuel in gas turbine engines poses challenges due to its gaseous state and increased flammability, which can lead to burn-back issues if ignition occurs too close to the fuel feed, and existing combustor structures designed for aviation fuel may not be suitable.
Innovation Solution
A combustor design incorporating a mixing body with inner and outer air passages that swirl air and deliver hydrogen fuel in a controlled manner, creating a controlled spray cone angle to manage combustion downstream, using hydrogen as the fuel source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If hydrogen is used as fuel in gas turbine engines, then energy density and efficiency are improved, but burn-back risk increases due to gaseous state and high flammability
Solution Approach 1:
The patent introduces an air-fuel mixer as an intermediary device between the fuel source and the combustion chamber. This mixer creates a controlled mixing zone where hydrogen gas is gradually mixed with air, forming a controlled gradient that prevents direct contact between high-concentration hydrogen and ignition sources, thereby reducing burn-back risk while maintaining energy density benefits
Solution Approach 2:
The system performs preliminary mixing of hydrogen and air in the air-fuel mixer before the combustion process begins. By pre-mixing the gases in a controlled manner and creating a diluted hydrogen cloud, the ignition process is delayed and controlled, preventing premature burn-back while preserving the high energy content of hydrogen fuel
2Device complexity
If existing combustor structures for aviation fuel are used, then structural simplicity is maintained, but combustion stability deteriorates due to unsuitability for hydrogen
Solution Approach 1:
The combustor structure is segmented into distinct functional zones: an air-fuel mixing section, a combustion section, and an exhaust section. This segmentation allows each zone to be optimized for its specific function - the mixing section handles hydrogen-air mixing while the combustion section maintains structural simplicity for ignition and burn, thereby achieving both structural simplicity and combustion stability
Solution Approach 2:
The patent applies local quality changes by creating different flow conditions and mixing intensities in different regions of the combustor. The air-fuel mixer creates a high-mixing-intensity zone near the fuel inlet, while downstream regions have progressively lower mixing intensity, allowing the structure to remain simple overall while achieving stable hydrogen combustion through localized mixing enhancement
3Device complexity
If hydrogen fuel is delivered directly to combustion chamber, then device complexity is minimized, but mixing efficiency deteriorates leading to unstable combustion
Solution Approach 1:
The air-fuel mixer serves as an intermediary device that improves mixing efficiency without significantly increasing overall device complexity. It uses the existing compressor air flow and fuel injection system, adding only a mixing chamber and guide vanes, thereby achieving efficient hydrogen-air mixing while maintaining relatively simple device architecture
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 design effectively controls the combustion process by ensuring hydrogen and air mix efficiently, reducing the risk of burn-back and maintaining stable combustion.
Implementation Method 1
a mixing body (104) attached to an end wall of the combustor (100)... mixes fuel and air to create an expanding cloud of mixed fluid
Implementation Method 2
Inner air swirler passages (118) are formed in the mixing body (104)... Outer air passages (120) are in the mixing body (104)
Implementation Method 3
Compressed air is mixed with fuel and ignited. Products of the combustion pass downstream over turbine rotors
Data Source
Figure 1~3B
Figure 2A~2B
AI summary
A combustor (100) for a gas turbine engine (20) includes a liner (102) receiving a fuel and air mixing body (104). The mixing body (104) communicates with a source of fuel (115), and has an inner chamber (111) centered on a central axis (116). Fuel passages (114) communicate with the source of fuel (115) and deliver fuel (115) into the inner chamber (111). The inner chamber (111) extends between a bottom wall (112) and an end face (110) leading into a combustion chamber (105) within the liner (102). Inner air swirler passages (118) are formed in the mixing body (104) at an axially intermediate location between the bottom wall (112) and the end face (110) and deliver air into the inner chamber (111) to mix with fuel (115) from the fuel passages (114). Outer air passages (120) are in the mixing body (104) in a portion which is radially outward of the chamber (111). The outer air passages (120) have a component extending radially inwardly toward the central axis (116) of the chamber (111).