Shape-Memory Alloy Guide Tubes for Gas Turbine Cavity Inspection
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Solution Overview
Problem
Existing inspection tools for gas turbine engines face challenges in accessing indirectly accessible cavities, requiring complex tooling and often leading to engine removals due to issues like powder metal defects, necessitating improved tool guidance and straightening mechanisms.
Innovation Solution
Utilization of smart metal alloy (SMA) guide tubes that can be memorized into a bent shape, inserted into the engine, heated to return to the bent shape for inspection, and then re-straightened for removal, optionally with hot air or a straightening rod, to facilitate inspection of inaccessible areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a straight rigid guide tube is used for insertion, then the guide tube can be easily inserted into the engine, but it cannot reach indirectly accessible cavities requiring bent paths
Solution Approach 1:
The guide tube utilizes shape memory alloy material that can change its physical state (shape) in response to temperature changes. The tube is heated to transform from a bent configuration to a straight configuration for insertion, then cooled to return to the bent configuration for navigating inaccessible cavities, thereby resolving the contradiction between ease of insertion and adaptability to complex paths
Solution Approach 2:
The guide tube transitions from a static straight shape to a dynamic shape-changing structure. The tube is memorized into a bent shape, then straightened during insertion, and subsequently returns to the bent shape to access cavities. This dynamic shape transformation allows the same tube to serve both insertion and navigation functions, eliminating the need for separate tooling configurations
2Adaptability or versatility
If complex tooling is used to access indirectly accessible cavities, then inspection capability is improved, but device complexity and potential for tooling errors increase
Solution Approach 1:
Instead of using complex mechanical tooling configurations, the invention changes the temperature parameter of the shape memory alloy guide tube to achieve shape transformation. This simple parameter change (heating/cooling) replaces complex mechanical adjustments, reducing tooling complexity while maintaining inspection capability
Solution Approach 2:
The guide tube autonomously transforms its shape in response to temperature changes without requiring external mechanical manipulation or complex control systems. The shape memory effect enables the tube to self-adjust from straight to bent configurations, eliminating the need for complex tooling mechanisms and reducing the risk of tooling errors
3Adaptability or versatility
If the guide tube is heated to return to bent shape for inspection, then accessibility to cavities is improved, but additional heating steps are required
Solution Approach 1:
The guide tube is pre-memorized into a bent shape during manufacturing, and the straightened configuration is prepared in advance for insertion. The heating step to return to the bent shape is a simple, pre-planned transition that enables immediate access to cavities, making the additional heating step worthwhile by eliminating the need for complex mechanical reconfiguration
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
Enables efficient inspection of indirectly accessible cavities in gas turbine engines, reducing engine removals and tooling errors, and enhancing inspection capabilities without damaging engine components.
Implementation Method 1
a guide tube formed of smart metal alloy (SMA) which has been memorized into a bent shape and then straightened
Data Source
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AI summary
A method of inspecting an indirectly accessible cavity of a gas turbine engine includes memorizing a guide tube (510) formed of smart metal alloy (SMA) into a bent shape and straightening the guide tube (510). The method also includes installing a scope (520), which includes a connecting line (521) to which an inspection element (522) is attached, into the guide tube (510). The method then includes inserting the guide tube (510) into the gas turbine engine toward a location of the indirectly accessible cavity, heating the guide tube to cause the guide tube (510) to return to the bent shape in order to bring the inspection element (522) into the indirectly accessible cavity and using the inspection element (522) to perform an inspection of the indirectly accessible cavity.