Diffusion Cone Flame-Holder Ring for Afterburner Core Stabilization
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Solution Overview
Problem
Existing turbojet engine designs face challenges in effectively stabilizing and fueling the flame at the core of the afterburner channel, leading to inefficient combustion and potential thrust reduction due to thermal profiles and vibrational phenomena.
Innovation Solution
A diffusion cone with an integrated flame-catching ring and fuel inlet, along with an annular thermal protection screen, enhances flame propagation and stabilization within the afterburner channel without altering the overall configuration, using secondary airflow for thermal protection and fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flame-arresting ring with C- or V-shaped cross-section is used to stabilize the flame, then flame stabilization is improved, but pressure drop increases due to obstruction of the afterburner channel
Solution Approach 1:
The flame-arresting ring is segmented into two separate branches (external and internal) that are rigidly connected at the base but have free ends downstream. This segmentation creates multiple flow paths through the ring structure, allowing the flame to be stabilized across different zones while reducing the overall pressure drop compared to a solid ring structure.
Solution Approach 2:
The invention transitions from a traditional single-branch C-shaped ring to a two-branch structure with both external and internal branches extending radially inward. This dimensional change creates a more complex three-dimensional flow pattern that enhances flame stabilization while managing pressure losses through distributed flow paths.
2Reliability
If a flame-arresting ring with free ends is used to promote recirculation zones, then flame stabilization is improved, but the ability to fuel the core of the afterburner channel is limited
Solution Approach 1:
The internal branch of the flame-arresting ring is specifically designed to extend radially inward to a position where it can effectively fuel the core of the afterburner channel. This localized extension ensures that fuel is delivered precisely where needed in the channel core, improving combustion in this critical region without compromising the overall flame stabilization function.
3Productivity
If the internal branch extends further radially inward to fuel the channel core, then combustion efficiency is improved, but structural integrity and flame stabilization may be compromised
Solution Approach 1:
The position of the internal branch is optimized to extend radially inward to a specific distance that balances two competing requirements: extending far enough to deliver fuel to the channel core for improved combustion efficiency, but not so far as to compromise the structural integrity and flame stabilization capabilities of the flame-arresting ring. This parameter optimization resolves the contradiction between productivity and reliability.
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
Improves flame attachment and stabilization at the afterburner channel core, enhancing combustion efficiency and thrust performance while minimizing vibrational interference.
Implementation Method 1
a flame-catching ring having a cross-section comprising an external branch and an internal branch rigidly connected to each other on the side of the base and such that the external branch extends around the internal branch
Implementation Method 2
an annular thermal protection screen which is arranged between the outer and inner branches so as to partially obstruct an opening through which the internal space of the flame-catching ring opens on the side opposite the base of the diffusion cone
Implementation Method 3
limiting harmful vibrational phenomena known as 'screech' in Anglo-Saxon terminology, by means of series of through or non-through holes, called 'anti-screech holes', made in the downstream part of the diffusion cone and/or by means of one or more boxes, called 'anti-screech boxes', attached to the internal surface of the diffusion cone
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A diffusion cone (33) for the rear part of a jet engine has a base (50) and, on an opposite side, a truncated tip defining an annular trailing edge (58), and comprises a flame-holder ring (70) with a cross section comprising an external branch (70A) and an internal branch (70B) which are connected to one another on the base (50) side and such that the external branch extends around the internal branch, whereby the external and internal branches delimit between them an internal space (72) opening on the opposite side to the base. One of the branches is made up of the annular trailing edge (58). The flame-holder ring comprises at least one fuel inlet (75) designed to let fuel into the internal space (72). Such a flame-holder ring makes it possible to ensure and to control the propagation of the flame within the afterburner channel.