Low-Pressure Nozzle Ring Clamping Pads for Wear and Corrosion
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Solution Overview
Problem
The nozzle ring elements in low-pressure turbines of aircraft turbojet engines suffer from friction-induced wear and type 2 corrosion at the root, leading to contact corrosion that deteriorates the parts and necessitates costly replacements and engine removals.
Innovation Solution
A turbomachine subassembly is designed with pads interposed between the root of the nozzle ring and the clamp, which protects the root from friction and corrosion, allowing easy replacement of worn pads instead of the entire nozzle ring element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the root of the nozzle ring element is clamped to hold it in place, then the nozzle ring element is securely attached to the casing, but the contact area is subjected to friction and corrosion leading to wear and deterioration
Solution Approach 1:
The invention introduces a pad as an intermediary element between the clamp and the root of the nozzle ring element. This pad is specifically designed to be replaceable and sacrificial, absorbing the friction and corrosion effects that would otherwise directly damage the root. The pad material is selected to withstand wear better than the root material, and its replaceability ensures that the critical root structure is protected from deterioration.
2Reliability
If the entire nozzle ring element is replaced when the root shows wear or corrosion, then the reliability is restored, but the maintenance cost and downtime increase significantly
Solution Approach 1:
The invention segments the attachment system into two distinct parts: the root (which is integral to the nozzle ring element and should be preserved) and the pad (which is a separate, replaceable component). This segmentation allows the pad to be replaced independently when worn, without needing to replace the entire nozzle ring element. The pad is designed as a separate insert that can be accessed and replaced during routine maintenance, significantly reducing maintenance costs and downtime while restoring reliability.
3Object-affected harmful factors
If an anticorrosion coating is applied to the root, then corrosion resistance is improved, but the coating does not persist due to friction in the contact area
Solution Approach 1:
The invention extracts the friction-bearing function from the root structure and places it onto the replaceable pad. By doing so, the root can be properly coated with anticorrosion materials without the coating being subjected to mechanical friction and wear. The pad, which experiences the friction, is designed to be replaced before its wear affects the coated root surface, thereby preserving the integrity and durability of the anticorrosion coating on the root.
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
Reduces maintenance costs and improves engine performance by minimizing wear and corrosion, enabling efficient pad replacement during inspections, thus reducing turbine disassembly and extending the engine's operational duration.
Implementation Method 1
this contact generates wear by friction (or fretting)
Implementation Method 2
The gases expand in the low-pressure nozzle ring. This accelerates the flow and deflects it
Data Source
AI summary
The turbomachine subassembly including at least one low-pressure nozzle ring, the nozzle ring including a root integral with the nozzle ring, a clamp configured so as to fasten the root to a casing of the turbomachine; and at least two pads interposed between the root and the clamp. Each pad being assembled in a form-fitting manner with one of either the root or the clamp.