Auxetic Lattice Casing for Gas Turbine Clearance Control
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Solution Overview
Problem
Gas turbine engine casings experience clearance variability due to thermal and mechanical loads, leading to inefficiencies and increased risk of tip rubs, which existing systems attempt to mitigate with complex and weight-increasing active clearance control systems.
Innovation Solution
An auxetic lattice structure integrated into the casing, manufactured additively, to resist growth and maintain clearances between static and rotating components, reducing the need for active control systems and enhancing thermal matching with adjacent components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If active clearance control systems are used to maintain clearances, then clearance stability is improved, but device complexity and weight increase
Solution Approach 1:
The casing structure itself provides clearance control through its lattice design that resists thermal and mechanical growth, eliminating the need for separate active control systems. The lattice structure autonomously maintains clearances by its inherent geometric properties rather than requiring external control mechanisms
Solution Approach 2:
The invention removes the need for complex active clearance control systems by extracting their function into the structural design of the casing itself. The lattice structure inherently provides the clearance maintenance function that previously required separate active systems
2Stability of the object's composition
If active clearance control systems are used to maintain clearances, then clearance stability is improved, but weight increases
Solution Approach 1:
The casing structure itself provides clearance control through its lattice design that resists thermal and mechanical growth, eliminating the need for separate active control systems. The lattice structure autonomously maintains clearances by its inherent geometric properties rather than requiring external control mechanisms
Solution Approach 2:
The invention removes the need for complex active clearance control systems by extracting their function into the structural design of the casing itself. The lattice structure inherently provides the clearance maintenance function that previously required separate active systems
3Ease of manufacture
If traditional single-wall casing is used, then manufacturing simplicity is maintained, but clearance variability increases
Solution Approach 1:
The casing wall is segmented into a lattice structure with multiple struts and cells rather than a solid wall. This segmentation allows the structure to resist thermal and mechanical growth while maintaining manufacturing feasibility through additive manufacturing processes
Solution Approach 2:
The invention changes the structural parameters of the casing from a solid wall to a lattice structure with specific geometric properties. The lattice parameters (strut thickness, cell size, orientation) are optimized to provide thermal and mechanical growth resistance while maintaining clearance consistency
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 auxetic lattice structure effectively maintains consistent clearances, reduces transient losses and temperatures, and minimizes the need for additional control systems, improving engine efficiency and reducing weight and complexity.
Implementation Method 1
structures such as an auxetic lattice structure can be integrated into the casing to resist growth and maintain clearances
Implementation Method 2
Auxetic structures resist growth in an expected direction
Implementation Method 3
the clearance between rotor blades, e.g., compressor rotor blades and turbine rotor blades, and an inner surface of the casing varies due to rotor growth and casing growth, e.g., through rotational speed of the rotor and thermal expansion of the rotating components and the casing
Data Source
AI summary
Casings and methods for manufacturing casings are provided. For example, a casing defining radial, axial, and circumferential directions is provided. The casing comprises an annular inner wall and an annular outer wall, each extending along the axial direction, with the outer wall radially spaced apart from the inner wall. The casing also comprises an auxetic structure extending from the inner wall to the outer wall and including a plurality of lattice elements. Each lattice element extends circumferentially and radially from the inner to the outer wall, and the lattice elements are axially spaced apart from one another. The auxetic structure may define at least one aperture for fluid flow from one portion to another of the auxetic structure and/or may be configured to vary the thermal characteristics of the casing along the axial direction. The casing may be integrally formed as a single monolithic component, e.g., by additive manufacturing.