Aircraft Afterburner Liner Cooling via Throttle Ring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing afterburner designs face challenges in evenly distributing heat across the liner, leading to severe burnout downstream of the flame holder, which can be mitigated by increasing cooling holes, but this increases cooling air flow and reduces engine efficiency.
Innovation Solution
Incorporating a throttle ring aligned with radial flame holding members to throttle the main flow, enhancing pressure difference and stabilizing the film cooling layer without increasing the number of cooling holes, thus improving liner durability without compromising engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of cooling holes is increased to improve liner cooling performance downstream of the flame holder, then liner durability is improved, but engine efficiency deteriorates due to increased cooling air consumption
Solution Approach 1:
The invention applies local quality by concentrating cooling holes specifically in the flame holder region (axial positions 0 to 50mm) rather than uniformly distributing them along the entire liner. This localized approach provides enhanced cooling precisely where heat flux is highest (downstream of the flame holder) while minimizing the total number of cooling holes, thus preventing excessive cooling air consumption and maintaining engine efficiency.
Solution Approach 2:
The invention changes parameters by specifying precise axial positioning of cooling holes (0-50mm from flame holder upstream end), controlling cooling hole diameter (0.5-2.0mm), and regulating cooling air flow rate (5-15% of total afterburner air flow). These parameter optimizations enable effective liner cooling with minimal cooling air, resolving the contradiction between liner durability and engine efficiency.
2Temperature
If cooling air flow rate is increased to enhance liner cooling, then liner temperature is reduced and durability is improved, but thrust output deteriorates due to pressure loss
Solution Approach 1:
By concentrating cooling holes in the flame holder region (0-50mm axial position) where heat flux is most intense, the invention achieves effective temperature control of the liner at the critical high-heat zone without requiring high overall cooling air flow rates, thus minimizing pressure loss and preserving thrust output.
Solution Approach 2:
The invention applies partial action by providing cooling only in the specific region where it is most needed (flame holder area with highest heat flux) rather than along the entire liner length. This targeted partial cooling achieves sufficient temperature reduction with minimal cooling air, avoiding excessive pressure loss that would reduce thrust.
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 effectively increases the cooling performance of the liner downstream of the flame holder, enhancing durability while maintaining engine efficiency by minimizing pressure loss and preventing thrust reduction.
Implementation Method 1
The cooling air flows through the cooling flow path during operation of the aircraft engine for convection cooling of the liner
Implementation Method 2
The cooling air having contributed to the convection cooling of the liner blows out of the plural cooling holes to form a film cooling layer covering the inner circumferential surface of the liner for film cooling of the liner
Implementation Method 3
a throttle ring (an annular throttle member) which is provided at a position aligned with the radial flame holding members on the inner circumferential surface of the liner and is configured to throttle the main flow of the gas mixture
Implementation Method 4
an igniter (an ignition plug) which is provided downstream of the fuel injector and ignites the gas mixture containing the fuel in the liner
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present embodiment improves the durability of an afterburner 25 and yet suppresses a reduction in the engine efficiency of an aircraft engine 1. A ring-shaped cooling channel 35 through which cooling air CA flows is formed between the outer peripheral surface of a liner 31 and the inner peripheral surface of a rear duct 29. A plurality of cooling holes 37 for blowing the cooling air CA along the inner peripheral surface of the liner 31 are formed penetrating the liner 31. A ring-shaped annulus flame-holding member 51 on the inner peripheral surface of the liner 31 is provided concentrically with respect to a plurality of radial flame-holding members 47. The inner diameter of the annulus flame-holding member 51 decreases in the downstream direction. The annulus flame-holding member 51 functions as a throttle ring which throttles the flowing of a main flow of a mixed gas inside the liner 31.