Gas Turbine Rotor Stage Attachment via Interlocking Features
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Solution Overview
Problem
Conventional methods for attaching rotatable parts in gas turbine engines, such as compressor and turbine stages, face challenges due to significant axial forces caused by pressure changes, limiting design freedom, increasing costs, weight, and size constraints.
Innovation Solution
A gas turbine engine design that uses a combination of mechanical fasteners and interlocking features, with optional thermal assembly through heating or cooling, to securely join rotatable parts, resisting relative axial movement and allowing for interference fits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional means are used to attach neighbouring rotor stages together, then the rotor stages can be held together, but the attachment mechanism becomes unacceptably large and heavy due to significant axial forces
Solution Approach 1:
The attachment mechanism is divided into two distinct functional elements: a mechanical fastener that provides primary attachment strength, and an interlocking feature (such as splines or keys) that provides secondary strength and resists axial movement. This segmentation allows each element to be optimized for its specific function, reducing the overall size and weight compared to a single conventional attachment mechanism that would need to handle all loads alone.
Solution Approach 2:
The interlocking feature introduces a geometric dimension to the attachment system through features such as splines, keys, or interdigitated profiles that engage in the radial or circumferential direction. This dimensional approach to load distribution allows axial forces to be resolved through geometric interlocking rather than relying solely on axial fastening elements, reducing the required size of the attachment mechanism.
2Stability of the object's composition
If stages are machined from a single metallic block, then all stages rotate at the same rate, but design freedom is limited and costs increase due to material constraints
Solution Approach 1:
The rotor assembly is segmented into separate rotor stages that are independently manufactured and then attached together using the dual joining mechanism. This segmentation allows each stage to be designed and manufactured from the most suitable material for its specific operating conditions (temperature, pressure, stress), while the mechanical fastener and interlocking feature ensure that all stages rotate together as a synchronized assembly, eliminating the need to machine from a single block.
Solution Approach 2:
The attachment mechanism serves multiple functions simultaneously: it mechanically fastens separate stages together, transmits torque between stages, resists axial forces from pressure changes, and ensures rotational synchronization. This multi-functionality allows independent stages with different materials and designs to work together as a unified rotating assembly.
3Strength
If conventional attachment methods are used for high pressure rise compressors, then attachment strength can be achieved, but the device size and weight become unacceptably large
Solution Approach 1:
The attachment system is segmented into a mechanical fastener for primary attachment and an interlocking feature for secondary attachment and axial force resistance. This segmentation allows the use of smaller, more compact components compared to a single conventional attachment mechanism, reducing the overall volume occupied by the attachment system while maintaining the required strength for high pressure rise compressor applications.
Solution Approach 2:
The attachment mechanism combines two different joining approaches (mechanical fastening and geometric interlocking) into a composite attachment system. This composite approach allows each component to be optimized for its specific function, enabling stronger attachment in a smaller package compared to conventional single-method attachment systems.
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
This approach enhances design freedom, reduces weight and size, and lowers costs by providing a robust and efficient method to attach rotatable parts in high-pressure environments, while maintaining operational stability.
Implementation Method 1
The first and second rotatable parts are engaged through the interlocking feature such that relative axial movement of the first and second rotatable parts is resisted by the interlocking feature
Implementation Method 2
The first and second rotatable parts are fixed together using a primary joining mechanism and a secondary joining mechanism. The primary joining mechanism is a mechanical fastener
Data Source
AI summary
A gas turbine engine has two connected parts that rotate together during use. The two parts have a tensile loading that acts to separate the two parts in use. The two parts may be neighbouring rotating stages of a gas turbine engine. The two parts are connected together using both a mechanical fastener and an interlocking feature. The interlocking feature may be, for example, interlocking conical surfaces and/or interlocking protrusions.