Fuel System Ice Debris Separator with Tortuous Filter Screen
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Solution Overview
Problem
Conventional aircraft fuel system filters are inadequate in managing ice and debris, as they either allow significant pressure drops or fail to filter debris effectively due to their design, and ice separators relying solely on geometry are ineffective at varying fuel flow speeds, posing a greater risk for Auxiliary Power Units (APUs) that are prone to icing.
Innovation Solution
A filter system with a cylindrical filter screen that surrounds the outlet, providing a tortuous path and bypass to prevent particles larger than 40 to 6000 microns while maintaining a pressure drop of less than 0.5 psi, effectively separating ice and debris by utilizing a combination of geometry and a filter screen to manage ice and debris without causing fuel starvation or pressure drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the filter is designed fine enough to filter debris to a desired fine level, then debris filtration is improved, but pressure drop increases significantly due to ice
Solution Approach 1:
The filter screen is segmented into multiple zones with different pore sizes and flow characteristics. The first zone provides coarse filtration while the second zone provides fine filtration, allowing the system to achieve both debris filtration and acceptable pressure drop by distributing the filtration load across different zones rather than relying on a single fine filter element.
Solution Approach 2:
Different portions of the filter screen have different filtration characteristics. The filter screen includes regions with varying pore densities and mesh configurations optimized for different functions: some areas prioritize debris capture while others prioritize flow maintenance, allowing the overall system to balance filtration effectiveness with pressure drop.
2Reliability
If the filter is designed with respect to ice and is inherently too coarse, then ice management is improved, but debris filtration to desired level is reduced
Solution Approach 1:
The filter screen is divided into multiple filtration zones with different mesh densities and pore characteristics. The first zone uses coarser mesh for ice and large debris, while the second zone uses finer mesh for smaller debris particles. This segmentation allows the system to handle both ice management and fine debris filtration simultaneously without compromising either function.
Solution Approach 2:
The filter screen incorporates both ice management features and fine debris filtration features, providing more than just ice management by including a second filtration zone that handles smaller debris particles. This partial action approach ensures that both ice and debris are effectively managed without requiring the filter to be overly coarse.
3Device complexity
If ice separators rely solely on geometry to separate ice and debris, then device complexity is reduced, but effectiveness is reduced due to wide range of fuel flow speeds
Solution Approach 1:
The filter screen acts as an intermediary element that bridges the gap between geometric separation and direct filtration. It provides a controlled filtration mechanism that works effectively across a wide range of fuel flow speeds by its physical mesh structure, which can adapt to different flow conditions while maintaining consistent debris and ice separation performance.
Solution Approach 2:
The filter screen's physical parameters (mesh density, pore size, mesh configuration) are optimized to work effectively across the wide range of fuel flow speeds typical of aircraft fuel systems. The screen's geometric parameters are designed to maintain effective separation regardless of flow velocity, combining simplicity with reliability across varying operating conditions.
4Manufacturing precision
If the filter screen provides fine filtration, then debris removal is improved, but the risk of fuel starvation increases due to pressure drop
Solution Approach 1:
The filter screen is segmented into multiple zones that distribute the filtration load. The first zone handles coarse debris and ice, while the second zone handles finer particles. This segmentation prevents any single zone from becoming a bottleneck that would cause fuel starvation, while still achieving the desired fine debris removal level through the combined action of both zones.
Solution Approach 2:
Different zones of the filter screen have different filtration characteristics optimized for their specific functions. The coarser first zone maintains high flow capacity while the finer second zone provides detailed debris removal. This local quality differentiation ensures that fine filtration is achieved without creating a uniform fine filter that would cause excessive pressure drop and fuel starvation.
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 filter system effectively prevents ice and debris from entering calibrated fuel system components, reducing the risk of icing and pressure drops, and ensures continuous fuel flow by incorporating a bypass mechanism that maintains a low pressure drop and efficient debris separation.
Implementation Method 1
the filter screen prevents passage of particles greater in size than 40 to 6000 microns
Implementation Method 2
the filter screen defines a tortuous path with a bypass there around
Data Source
AI summary
A filter includes an outlet from a container, the outlet transverse to said inlet and a filter screen within the container that partially surrounds the outlet. In a further embodiment of the foregoing embodiment, the filter screen prevents passage of particles greater in size than 40 to 6000 microns. In a further embodiment of any of the foregoing embodiments, the filter screen provides a pressure drop of less than 0.5 psi. In a further embodiment of any of the foregoing embodiments, the filter screen defines a tortuous path with a bypass there around. In a further embodiment of any of the foregoing embodiments, the filter screen is cylindrical and extends parallel to a length of said container.