Airfoil Mesh Last Chance Screen for Aircraft Fuel Coking
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Solution Overview
Problem
Current last chance screens in aircraft fuel systems are susceptible to coking, leading to pressure drops and clogging due to insoluble deposits, which are exacerbated by increasing fuel temperatures, causing efficiency issues and component clogging in aircraft engines.
Innovation Solution
A last chance screen with a mesh of airfoil-shaped members intersecting in a specific pattern, reducing recirculation zones and preventing deposit formation, combined with a PTFE coating to inhibit deposit accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional mesh screens are used to filter particles, then particle filtration is achieved, but coking and deposit accumulation occur leading to pressure drops and clogging
Solution Approach 1:
The screen members are given an airfoil-shaped cross-section with curved surfaces instead of flat or circular profiles. This curvature eliminates recirculation zones where deposits would accumulate, while maintaining the filtering function through appropriately sized openings between the curved members.
Solution Approach 2:
The airfoil cross-section is an asymmetric shape with a rounded leading edge and a tapered trailing edge. This asymmetric geometry creates unidirectional flow patterns that prevent deposit accumulation on the screen surface while maintaining effective particle filtration.
2Productivity
If fuel temperature is increased to improve efficiency, then engine performance improves, but susceptibility to coking increases
Solution Approach 1:
The curved airfoil surfaces of the screen members eliminate stagnant recirculation zones that would otherwise promote coking at elevated temperatures. This allows the fuel to be heated for improved efficiency without the accompanying increase in deposit formation.
3Reliability
If mesh openings are reduced to improve filtration, then particle removal efficiency increases, but pressure drop across the screen increases
Solution Approach 1:
The airfoil-shaped members with their curved surfaces reduce flow separation and turbulence, allowing for smaller openings that maintain filtration efficiency while minimizing pressure drop across the screen.
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 airfoil-shaped mesh design and PTFE coating significantly reduce coking, allowing fuel to flow efficiently at higher temperatures without pressure drops, enhancing engine efficiency and extending screen lifespan by preventing deposit accumulation.
Implementation Method 1
The first plurality of members and the second plurality of members have an airfoil shaped cross-section
Implementation Method 2
combined with a PTFE coating to inhibit deposit accumulation
Data Source
AI summary
A last chance screen for a fuel system includes a mesh that includes a first plurality of members extending in a first direction and a second plurality of members extending in a second direction and intersecting the first members. Openings are formed in the mesh between the first plurality of members and the second plurality of members. The first plurality of members and the second plurality of members have an airfoil shaped cross-section.