Aircraft Injector Assembly With Radial Airflow to Prevent Flashback
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Solution Overview
Problem
Existing injector arrangements for aircraft engines face challenges in managing thermal loads and flame stability due to the proximity of the combustion zone to the injector body, particularly when introducing gaseous fuels like hydrogen, which can lead to auto-ignition and flame flashback.
Innovation Solution
The injector arrangement features a radial outward flow design for air and gaseous fuel, delayed mixing through high-velocity streams, and a specific channel configuration that shifts the combustion zone away from the injector body, using high-velocity air and gaseous fuel streams to minimize thermal stress and prevent premature ignition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the combustion zone is positioned close to the injector body for compact design, then the engine structure is more compact, but the thermal load on the injector increases and flame flashback risk increases
Solution Approach 1:
The patent introduces a radial outward flow component in addition to the axial flow, creating a two-dimensional flow pattern. The outer air duct directs airflow radially outward while the inner air duct provides axial flow, and the gaseous fuel is injected radially outward between these flows. This dimensional change extends the combustion zone downstream and radially outward, distancing it from the injector body while maintaining a compact overall structure.
2Productivity
If gaseous fuel is introduced at high velocity for efficient combustion, then combustion efficiency improves, but the risk of auto-ignition and flame flashback increases
Solution Approach 1:
The patent uses the outer air flow as an intermediary medium between the injector body and the gaseous fuel jet. This outer air flow acts as a protective barrier that stabilizes the flame front and prevents it from propagating back toward the injector. The gaseous fuel is injected into this controlled air environment, which allows high-velocity injection for efficiency while the outer air flow prevents auto-ignition and flame flashback, ensuring reliability.
3Device complexity
If the outer air duct directs airflow axially for simple design, then the duct design is simpler, but the mixing of air with gaseous fuel occurs too early increasing thermal load
Solution Approach 1:
The patent segments the air supply into two separate ducts with distinct functions: the inner air duct provides axial airflow for cooling and base combustion, while the outer air duct provides radial outward airflow for controlled mixing. This segmentation allows each duct to be optimized for its specific function - the outer duct creates a flow pattern that delays mixing until downstream, reducing thermal load on the injector while maintaining relatively simple individual duct designs.
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
This design reduces thermal load on the injector and prevents auto-ignition and flame flashback, enhancing operational safety and reducing emissions by optimizing the combustion zone's location and fuel distribution.
Implementation Method 1
the outer air duct for supplying the external airflow into the combustion chamber is designed at high velocity, between 50 m/s and 150 m/s, particularly between 80 m/s and 100 m/s
Implementation Method 2
the outer air duct has a radially outwardly oriented end section at its downstream end for directing the external airflow flowing into the combustion chamber radially outwards
Implementation Method 3
The momentum of the axially radially flowing airflow, into which the gaseous fuel exiting the outlet is introduced, also deflects the gas flow axially and radially outwards
Data Source
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AI summary
The invention relates to an injector arrangement (1) for an engine, in particular of an aircraft, for introducing a gaseous fuel and a liquid fuel as well as air into a combustion chamber (CC), comprising an injector shaft (2) and an injector main body (3) aligned along an injector longitudinal axis (L), wherein the injector main body (3) comprises: - a central air channel (14) arranged on the injector longitudinal axis (L) with an outlet opening (16) for directing a central airflow, - an outer air channel (36) arranged radially around the central air channel (14) with an outlet opening (40) for directing an outer airflow, - a liquid fuel supply (20) arranged radially between the central air channel (14) and the outer air channel (36) with at least one liquid fuel channel (22) and an outlet opening (24) for introducing the liquid fuel,and - a gas fuel supply (30) arranged radially between the liquid fuel supply (20) and the outer air duct (36), with at least one gas fuel channel (31) and an outlet opening (34) for introducing the gaseous fuel. An emission-optimized flow pattern is achieved by the outer air duct (36) having a radially outwardly oriented end section (37) at its downstream end for directing the external airflow entering the combustion chamber (CC) radially outwards.