Aircraft Igniter Plug Scoops for Fuel Residue Extraction
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Solution Overview
Problem
Semiconductor igniter plugs in aircraft turbomachines face issues with fuel residues accumulating in the electric arc forming cavity, leading to insulation, coke formation, and potential malfunctions due to vertical or tilted orientations, which hinder spark formation and increase the risk of arc misalignment or structure cracking.
Innovation Solution
The design incorporates discharging scoops on the external electrode, specifically notches that extend between the cavity and the outer side surface, allowing fuel residues to be extracted by gravity and the airflow, reducing coke formation and prolonging plug lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the plug is vertically oriented or weakly tilted to facilitate maintenance accessibility, then maintenance operations are easier, but fuel residues accumulate in the cavity due to gravity
Solution Approach 1:
The external electrode is segmented by introducing notches that divide the electrode structure into sections, creating discharge paths that allow fuel residues to be removed from the cavity while maintaining the vertical orientation for maintenance accessibility
Solution Approach 2:
The notches in the external electrode create extraction paths that remove fuel residues from the cavity, separating the fuel residue removal function from the main electrode structure while preserving the vertical plug orientation
2Quantity of substance
If fuel residues fill the cavity, then the cavity is wetted, but this prevents electric arc formation and causes arc blowing
Solution Approach 1:
The notches provide extraction paths that remove fuel residues from the cavity before they can interfere with electric arc formation, ensuring the cavity remains free of insulating fuel deposits that would prevent proper arc development
Solution Approach 2:
The discharge scoops create preliminary anti-action by removing fuel residues before they can accumulate to levels that would prevent arc formation or cause arc blowing, proactively preventing the harmful effect rather than reacting to it
3Temperature
If fuel residues remain in the hot cavity at shutdown, then coke formation occurs on the semiconducting body, but this leads to plug malfunctions and short-circuiting
Solution Approach 1:
The notches continuously extract fuel residues from the cavity, preventing their accumulation on the semiconducting body surface where they would otherwise carbonize into conductive coke deposits during hot shutdown conditions
Solution Approach 2:
The discharge scoops perform preliminary action by removing fuel residues before they can undergo thermal decomposition and coke formation during shutdown, preventing the subsequent harmful effect of conductive deposits
4Use of energy by moving object
If energy is delivered to break down fuel residues, then breakdown may occur, but this generates shock waves that crack or rupture the semiconducting body
Solution Approach 1:
The notches extract fuel residues from the cavity, removing the target material that would require high-energy breakdown and subsequent shock wave generation, thereby eliminating the source of damage to the semiconducting body
Solution Approach 2:
The design converts the potential harm of fuel residue accumulation into a benefit by using the natural flow and gravity to automatically remove residues through the notches, eliminating the need for high-energy breakdown that would damage the semiconducting body
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 scoops effectively prevent fuel residue accumulation, minimizing malfunctions and extending the plug's operational life by ensuring consistent spark formation and reducing the risk of structural damage.
Implementation Method 1
The presence of one or more discharging scoops advantageously enables the possible fuel residues to be extracted from the cavity, by gravity and/or using the stream fitting closely the plug nose, in use.
Implementation Method 2
The presence of one or more discharging scoops advantageously enables the possible fuel residues to be extracted from the cavity, by gravity and/or using the stream fitting closely the plug nose, in use.
Implementation Method 3
The semiconducting body is set back from the internal and external electrodes, so as to define an electric arc forming cavity.
Implementation Method 4
even in other plug orientations, the cavity is likely to be wet by fuel residues adhering by capillarity to the semiconducting body.
Data Source
AI summary
An igniter plug for an aircraft turbomachine includes an external electrode, an internal electrode, as well as a semiconducting body arranged between the external electrode and the internal electrode and set back from these electrodes so as to define an electrical arc forming cavity, the bottom of which is formed by an axial end surface of the semiconducting body. The free end of the external electrode is equipped with at least one scoop for discharging possible fuel residues present in the cavity.