Aircraft Fuel Tank Pipe Semiconductor Coating Lightning Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft fuel tanks using carbon fiber reinforced plastics (CFRP) and aluminum alloy pipes face risks of lightning-induced sparks and static electricity sparks due to resistance differences and flow electrification, which can ignite fuel.
Innovation Solution
The fuel tank incorporates a pipe with a semiconductor outer surface layer and an optional semiconductor inner surface layer, providing resistance values between 10^3Ω and 10^9Ω to suppress lightning current flow and static electricity accumulation, thereby preventing sparks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If aluminum alloy pipes are used for fuel supply, then lightweight and high strength are achieved, but lightning current flow causes spark danger at pipe joints
Solution Approach 1:
A semiconductor layer is introduced as an intermediary between the aluminum alloy pipe and the CFRP airframe structure. This semiconductor layer acts as a mediator that limits current flow during lightning strikes while maintaining electrical connectivity, thereby preventing sparks at pipe joints without compromising the structural integrity or lightweight properties of the aluminum alloy pipe.
Solution Approach 2:
The electrical conductivity parameter of the pipe surface is modified by applying a semiconductor coating. This changes the resistance characteristics from highly conductive (aluminum alloy) to controlled semi-conductive, limiting lightning current flow while still allowing static electricity dissipation. The semiconductor layer's resistance parameter is specifically chosen to balance these two opposing requirements.
2Object-affected harmful factors
If GFRP insulator pipes are used to prevent lightning current flow, then spark danger from lightning is reduced, but static electricity accumulates due to flow electrification
Solution Approach 1:
The electrical conductivity parameter is precisely controlled by selecting semiconductor materials with specific resistance values. The semiconductor coating provides high enough resistance to block lightning current (which carries very high voltage but brief duration) while maintaining low enough resistance to allow gradual dissipation of static electricity charges that build up during fuel flow operations.
Solution Approach 2:
Instead of using expensive and heavy metal pipes or complex bonding systems, a thin semiconductor coating is applied to the pipe surface. This coating is relatively simple to apply and provides the necessary electrical characteristics to handle both lightning strikes and static electricity without requiring complex additional systems.
3Weight of moving object
If CFRP is used for airframe materials, then lightweight and high strength are achieved, but resistance difference with aluminum pipes increases potential difference and spark danger
Solution Approach 1:
The semiconductor layer serves as an intermediary that bridges the electrical property gap between CFRP and aluminum alloy. It provides a controlled electrical pathway that equalizes potential differences during normal operation and limits current during lightning events, preventing sparks at the interface between these two materials.
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 semiconductor-coated pipe surfaces effectively diffuse electrical charges and prevent sparks, enhancing safety by ensuring the suppression of lightning and static electricity-induced ignition risks.
Implementation Method 1
because the pipe outer surface layer conducts electricity better than an insulator, any electrical charge that accumulates on the outer surface of the pipe due to flow electrification caused by the fuel can be readily diffused
Implementation Method 2
the outer surface of the pipe has a greater resistance than the conductive skins and spars. As a result, regardless of how the pipe is bonded to the airframe structure, the flow of a lightning current into the pipe during a lightning strike can be suppressed
Implementation Method 3
flow electrification between the GFRP and the fuel tends to accumulate on the GFRP. As a result, the danger of a static electricity spark acting as an ignition source for the fuel cannot be ignored
Data Source
AI summary
An aircraft fuel tank that is capable of suppressing the occurrence of sparks on a pipe caused by a lightning current through the pipe during a lightning strike, and also suppressing static electricity charging of a pipe caused by flow electrification generated by the fuel. An aircraft fuel tank (1) in which a storage section is formed using a conductive upper skin (5), a conductive lower skin (7) and conductive spars (9), the tank comprising: pipes inside the tank, such as a refuel pipe (17), an engine feed pipe (19) and an inert gas pipe (21), which are disposed inside the storage section and are earthed (27) at a plurality of locations, and pipe outer surface layers (31) having semiconductor properties that are formed in an integrated manner on the outer surfaces of the pipes inside the tank such as the replenishing pipe (17), the supply pipe (19) and the gas pipe (21).