Turbomachine Ignition Plug Guide Deflector Wear Reduction
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Solution Overview
Problem
The ignition plug in an annular combustion chamber of a turbomachine experiences premature wear due to high contact pressure and aerodynamic forces, leading to increased wear in the contact zone between the guide and the plug.
Innovation Solution
A deflector is introduced around the guide that extends into the air flow stream to reduce aerodynamic pressure on the guide, thereby reducing the contact pressure between the guide and the plug, with the deflector being annular and extending over at least 180°, preferably 360°, and fastened to the chimney.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the guide extends into the air flow stream, then the guide is pressed against the plug by aerodynamic pressure, but this causes high contact pressure and premature wear of the plug
Solution Approach 1:
A deflector is introduced as an intermediary element between the air flow stream and the guide. The deflector redirects the aerodynamic pressure away from the guide, preventing the air flow from pressing the guide against the plug. This mediator component solves the contradiction by allowing the guide to extend into the air flow stream for sealing purposes while eliminating the harmful pressing effect that causes wear.
Solution Approach 2:
The deflector converts the harmful aerodynamic pressure into a beneficial force by redirecting it. Instead of allowing the air flow to press the guide against the plug (harmful), the deflector redirects this pressure to act on the deflector itself, which is designed to withstand and redirect these forces away from the critical plug-guide contact zone.
2Adaptability or versatility
If clearance is provided between the guide and plug, then axial and radial movements are accommodated during differential expansion, but functional clearance causes the guide to move in translation and turn about the plug due to vibration and air flow
Solution Approach 1:
The deflector acts as a mediator that stabilizes the guide-plug interface. By redirecting aerodynamic forces away from this interface, the deflector reduces the relative movement and turning motion between the guide and plug that occurs during operation, thereby reducing wear while maintaining the necessary clearance for thermal expansion.
3Adaptability or versatility
If the guide is mounted with clearance on the chimney, then differential expansion during flight stages is accommodated, but this clearance allows vibration and air flow to cause turning motion increasing wear
Solution Approach 1:
The deflector serves as a mediator that reduces the dynamic forces transmitted through the clearance between the guide and chimney. By redirecting the air flow, the deflector minimizes the vibration-induced turning motion that occurs at the clearance interface, thereby protecting the plug from premature wear while preserving the thermal expansion accommodation capability.
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 deflector significantly reduces the wear of the ignition plug by mitigating the effects of aerodynamic pressure and vibration, enhancing the longevity of the plug.
Implementation Method 1
the guide extending at least in part in an air flow stream outside the chamber, wherein the guide means comprise a deflector surrounding the portion of the guide that is situated in the air flow stream so as to reduce the aerodynamic pressure on the guide
Data Source
AI summary
A turbomachine combustion chamber including at least one ignition plug carried by an outer casing and extending within guide means carried by a wall of the chamber, the wall forming a body of revolution. The guide means includes a tubular guide having the plug passing axially therethrough and mounted with axial and transverse clearance on a chimney fastened to the wall of the chamber and opening out into the chamber, the guide extending at least in part in an air flow stream outside the chamber. The guide means includes a deflector surrounding the portion of the guide that is situated in the air flow stream so as to reduce the aerodynamic pressure on the guide and reduce the contact pressure of the guide on the plug.