Afterburner Flame Holder Guide Ring Design
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Solution Overview
Problem
The existing afterburner systems face challenges in ensuring stable ignition and flame holding while maintaining engine efficiency, as the diffusion of fuel affects proper evaporation and concentration at the ignition point, and the annulus flame holding member interferes with the main flow, leading to increased pressure loss.
Innovation Solution
The afterburner design includes a cylindrical liner with a fuel injector, an igniter, and a flame holder with an annulus flame holding member on the inner surface and radial members, along with a guide ring forming an annular guide flow path to ensure proper fuel concentration and evaporation, and to minimize interference with the gas mixture flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the annulus flame holding member is situated away from the inner circumferential surface of the liner, then flame propagation in the circumferential direction is improved, but pressure loss in the liner is increased
Solution Approach 1:
A guide ring is introduced as an intermediary component between the annulus flame holding member and the liner. The guide ring creates a guide flow path that directs the gas mixture containing fuel along the inner circumferential surface, enabling the flame to propagate effectively while preventing direct interference with the main flow. This mediator allows the flame holding function to be achieved without the pressure loss penalty of positioning the flame holding member away from the liner surface.
2Ease of manufacture
If the fuel injector is positioned to supply fuel downstream in the liner, then fuel delivery is simplified, but fuel cannot be supplied at proper evaporated state and proper concentration simultaneously at the ignition place
Solution Approach 1:
The guide ring performs preliminary action by directing the fuel-containing gas mixture along a controlled path before it reaches the ignition location. This pre-positioning and pre-mixing action ensures that fuel is delivered at the proper evaporated state and concentration exactly where needed for ignition, while maintaining the simplicity of downstream fuel injector positioning. The guide flow path prepares the mixture in advance, eliminating the need for complex injector positioning.
3Loss of energy
If the annulus flame holding member is placed on the inner circumferential surface of the liner, then pressure loss is reduced, but flame propagation capability may be insufficient
Solution Approach 1:
The flame holding function is segmented into two distinct components: the annulus flame holding member that contacts the liner to minimize pressure loss, and the guide ring that creates a dedicated flow path for flame propagation. This segmentation allows each component to perform its specific function optimally - the flame holding member maintains low pressure loss by staying on the liner surface, while the guide ring ensures adequate flame propagation through controlled gas flow guidance.
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 configuration stabilizes ignition and enhances flame propagation, maintaining engine efficiency by ensuring proper fuel delivery and minimizing pressure loss, thus achieving sufficient ignition and flame holding capabilities.
Implementation Method 1
the fuel cannot be supplied to an ignition place of the igniter at proper evaporated state and proper concentration
Implementation Method 2
an igniter (an ignition plug) which is provided downstream of the fuel injector and ignites the gas mixture containing the fuel
Implementation Method 3
the flame holder includes: plural radial frame holding members which are provided in a radial fashion within the liner and are capable of propagating flame in the radial direction; and an annulus flame holding member which is situated away from the inner circumferential surface of the liner and is capable of propagating flame in the circumferential direction
Data Source
Figure 1
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AI summary
The present embodiment sufficiently ensures the ignition stability and the flame-holding property of an afterburner 25 while suppressing a reduction in the engine efficiency of an aircraft engine 1. A flame holder 45 is disposed directly downstream of an injection hole 41 of a fuel injector 39 in a liner 31. The flame holder 45 comprises: a ring-shaped annulus flame-holding member 49 which is provided on the inner circumferential surface of the liner 31 and is capable of propagating a flame in the circumferential direction; and a plurality of radial flame-holding members 51 which are radially disposed inwards of the annulus flame-holding member 49 and are capable of propagating the flame in the radial direction. A guide ring 53 is provided inwards of the radial flame-holding members 51, and a ring-shaped guide channel 57 that guides a fuel-containing mixed gas in the downstream direction is formed between the outer peripheral surface of the guide ring 53 and the inner peripheral surface of the annulus flame-holding member 49.