Fuel Swirler Apertures Prevent Flashback in Aircraft Engines
Solution Overview
Problem
Existing fuel nozzles are designed for a single type of fuel and risk ignition of gaseous fuels like hydrogen when mixed with compressed air, potentially leading to dangerous flame propagation.
Innovation Solution
A fuel supply system with a fuel swirler featuring discrete apertures at the fuel inlet, an insert with an annular body and apertures, and a dual fuel path for gaseous and liquid fuels, ensuring safe mixing and combustion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-type fuel nozzle design is used, then the device complexity is reduced, but the adaptability to different fuel types deteriorates
Solution Approach 1:
The fuel nozzle is designed with a universal structure that can handle multiple fuel types (gaseous and liquid fuels) through a single device. The nozzle incorporates separate fuel paths and appropriately sized orifices that work with different fuel properties, eliminating the need for multiple specialized nozzles while maintaining adaptability across fuel types.
2Productivity
If gaseous fuel is mixed with compressed air at the nozzle, then the mixing efficiency is improved, but the risk of premature ignition and flame propagation increases
Solution Approach 1:
The mixing process is segmented into distinct zones: fuel injection, initial mixing, and combustion. By separating the fuel injection function from the combustion function and providing adequate spacing between the nozzle and combustor, the design achieves efficient mixing while preventing premature ignition through spatial segmentation of hazardous processes.
Solution Approach 2:
The nozzle design incorporates an intermediary mixing zone where fuel and air begin to mix before entering the combustor. This intermediate region allows controlled mixing to occur away from ignition sources, acting as a buffer that prevents direct contact between highly reactive fuel-air mixtures and potential ignition sources.
3Reliability
If discrete apertures are added to the fuel swirler, then the flashback prevention capability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The fuel swirler incorporates a porous structure with discrete apertures that serve as a flashback arrestor. The porous nature of the structure provides multiple flow paths and surface area for flame quenching, preventing flashback while the standardized aperture patterns can be manufactured using established porous material fabrication techniques.
Solution Approach 2:
The aperture dimensions are optimized to specific parameter ranges that balance flashback prevention with manufacturability. By establishing standardized aperture size and distribution patterns, the design achieves reliable flashback protection while accommodating conventional manufacturing tolerances through careful parameter selection.
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 system allows for the safe injection and combustion of different fuel types, including gaseous fuels, by preventing early ignition and ensuring efficient mixing, thereby enhancing the durability and safety of the fuel nozzle.
Implementation Method 1
the plurality of discrete apertures are positioned at the fuel inlet of the fuel swirler... there is a risk that the gaseous fuel ignites as soon as it comes into contact with compressed air at or before a mixing site. This may lead to dangerous and/or damaging consequences if the flame were to propagate upstream through the fuel nozzle.
Implementation Method 2
Compressed fuel is typically fed under pressure into a central fuel swirler and a surrounding array of pressurized air flow channels is provided to form an atomized air/fuel mixture.
Implementation Method 3
a surrounding array of pressurized air flow channels is provided to form an atomized air/fuel mixture
Implementation Method 4
the combined configuration of control surfaces between the swirler housing and swirler core define fuel flow channels and shaped surfaces that control the direction, pressure and kinetic energy of the pressurized fuel flow
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A fuel supply system for an aircraft engine, comprises a gaseous fuel source (S1) and a fuel nozzle (20). The fuel nozzle (20) includes a housing (30) having a housing interior chamber and a fuel swirler (40) disposed inside the housing interior chamber. The fuel swirler (40) is fluidly connected to the gaseous fuel source (S1) for directing gaseous fuel to a combustor of the aircraft engine. The fuel swirler (40) defines a gaseous fuel path extending from a fuel inlet to a fuel outlet (55). The gaseous fuel path includes a plurality of discrete apertures distributed around a circumference of the fuel swirler (40), each of the plurality of discrete apertures having a cross-sectional area selected to prevent a flame from propagating in an upstream direction through the gaseous fuel path towards the gaseous fuel source (S1).