Aircraft Exhaust Duct Deformed Segment for Fuel Drainage
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Solution Overview
Problem
Existing exhaust ducts in aircraft can accumulate unburnt fuel at low points, leading to undrainable volumes that exceed certification limits, necessitating heavy drainage systems.
Innovation Solution
An innovative exhaust duct design featuring a deformed segment with non-circular bottom sectors, which reduces the volume of liquid that can accumulate by modifying the geometry to prevent liquid from reaching the inlet and outlet sections within predetermined pitch and roll angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional exhaust duct with circular sections is used, then the structure is simple and easy to manufacture, but unburnt fuel accumulates at low points creating undrainable volume exceeding certification limits
Solution Approach 1:
The exhaust duct transitions from circular sections to a deformed segment configuration where the bottom sector is flattened. This asymmetric geometry prevents fuel accumulation by eliminating the low point where gravity would cause undrainable volume, while maintaining manufacturability through standardized forming processes.
Solution Approach 2:
The cross-sectional geometry of the exhaust duct is modified by changing the shape parameter from circular to a deformed segment with a flattened bottom. This parameter change alters the flow characteristics and eliminates fuel trapping while keeping the overall duct structure simple and manufacturable.
2Reliability
If a heavy drainage system is installed to remove accumulated fuel, then certification requirements are met, but the aircraft weight increases significantly
Solution Approach 1:
The drainage system is completely removed from the aircraft by preventing fuel accumulation at the source. The deformed segment geometry inherently eliminates undrainable volume, making any additional drainage equipment unnecessary and thereby reducing aircraft weight while maintaining certification compliance.
Solution Approach 2:
The exhaust duct geometry itself performs the drainage function by preventing fuel accumulation through its deformed segment shape. The structure is self-draining due to the flattened bottom sector that eliminates low points, making external drainage systems redundant.
3Quantity of substance
If the exhaust duct geometry is modified to prevent fuel accumulation, then undrainable volume is reduced, but the aerodynamic performance may be affected
Solution Approach 1:
Only the bottom sector of the exhaust duct cross-section is deformed to prevent fuel accumulation, while the top sector and overall duct configuration remain unchanged. This localized modification minimizes impact on aerodynamic performance while effectively eliminating undrainable fuel volume.
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 design minimizes the undrainable volume of unburnt fuel, eliminating the need for a specific drainage system and optimizing weight, while maintaining acceptable aerodynamics and adhering to certification requirements.
Implementation Method 1
so that at least a volume of liquid that is not able to reach, by force of gravity, the inlet section and the outlet section, is less than a volume threshold
Data Source
AI summary
An exhaust duct configured to be arranged around an exhaust nozzle of an engine, the exhaust duct having a plurality of sections. The sections are circular between an inlet section and an outlet section, with the exception of the sections of a deformed segment, each section of the deformed segment extending from a bottom sector to a top sector, the bottom sector having a non-circular shape so that at least a volume of liquid that is not able to reach, by force of gravity, the inlet section and the outlet section, is less than a volume threshold when the pitch and roll angles respectively lie within predetermined pitch and roll angle ranges.