Fuel Plenum Mixing Passages for Hydrogen Flashback 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 higher flammability, which can lead to flashback issues if the local flame speed exceeds the fuel-air mixture inlet speed, making existing combustor structures designed for liquid aviation fuel inadequate.
Innovation Solution
A combustor design featuring a fuel plenum with mixing passages that utilize porous metal foam or cellular metallic materials to delay ignition downstream and act as a flame arrestor, controlling fuel-air mixture exit velocity to prevent flashback, while incorporating a non-planar inner face and varying passage lengths to optimize flame stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If hydrogen fuel is used in gas turbine engines, then fuel efficiency and environmental performance are improved, but flashback risk increases due to higher flame speed exceeding fuel-air mixture inlet speed
Solution Approach 1:
A porous insert material is introduced as an intermediary between the fuel-air mixture inlet and the combustion zone. This insert acts as a mediator that reduces the flame propagation speed through the porous structure, preventing flashback while allowing efficient combustion to occur downstream.
Solution Approach 2:
The patent employs porous materials (such as metal foams or ceramic matrices) within the combustor structure. These porous materials create a tortuous flow path that increases residence time and reduces flame speed, effectively preventing flashback while maintaining combustion efficiency for hydrogen fuel.
2Device complexity
If combustor structure is designed for liquid aviation fuel, then structural simplicity is maintained, but it becomes inadequate for gaseous hydrogen fuel due to different combustion characteristics
Solution Approach 1:
The combustor design incorporates a porous insert that provides multi-functionality: it serves as a flow distributor, flame speed reducer, and combustion stabilizer. This single component enables the combustor to handle different fuel types (liquid aviation fuel and gaseous hydrogen) effectively, enhancing adaptability without proportionally increasing complexity.
3Productivity
If flame ignition occurs upstream, then combustion efficiency is reduced, but delaying ignition downstream requires extended passage lengths
Solution Approach 1:
The porous insert compresses the effective combustion zone within a shorter axial length by creating extensive surface area for combustion reactions. The porous structure provides numerous ignition sites and maintains flame stability without requiring long passage lengths, thus improving combustion efficiency while minimizing combustor size.
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 prevents flashback and stabilizes flames, ensuring safe and efficient combustion of hydrogen fuel by delaying ignition and controlling flame propagation.
Implementation Method 1
The mixing passages pass through a fuel plenum. Fuel openings in the mixing passages allow fuel to flow from the fuel plenum into the mixing passages and mix with the air. Passage sections extend downstream of the fuel plenum, such that the mixed air and fuel travels downstream of the fuel plenum and into a combustion chamber.
Implementation Method 2
A combustor design featuring a fuel plenum with mixing passages that utilize porous metal foam or cellular metallic materials to delay ignition downstream and act as a flame arrestor, controlling fuel-air mixture exit velocity to prevent flashback
Implementation Method 3
Compressed air is mixed with fuel and ignited. Products of the combustion pass downstream over turbine rotors, driving them to rotate.
Implementation Method 4
A wall of the mixing body has air openings to receive air flow and communicate air into mixing passages
Implementation Method 5
Compressed air is mixed with fuel and ignited. Products of the combustion pass downstream over turbine rotors, driving them to rotate.
Data Source
Figure 1
Figure 2A~2C
Figure 3A~4
AI summary
A combustor (100; 200) for a gas turbine engine (20) includes a liner (102; 202) surrounding a fuel and air mixing body (104; 204). A fuel supply passage (118; 218) communicates into an open fuel plenum (120; 220) downstream of the fuel supply passage (118; 218). A wall (199; 299) of the mixing body (104; 204) has air openings (106; 206) to receive air flow, and communicate air into mixing passages (107; 207). The mixing passages (107; 207) pass through the fuel plenum (120; 220). Fuel openings (122; 222) in the mixing passages (107; 207) allow fuel to flow from the mixing passage and mix with the air. There are passage sections (108; 208) extending downstream of the fuel plenum (120; 220), such that the mixed air and fuel travels downstream of the fuel plenum (120; 220) and into a combustion chamber (105; 205). A gas turbine engine (20) is also disclosed.