Variable Flowpath Casing Smart Structures for Blade Tip Clearance

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Solution Overview

Problem

Turbine engine performance is adversely affected by varying tip clearances between rotor blades and casings due to differential thermal expansion of materials, leading to issues such as blade tip rubbing, performance losses, and instability.

Innovation Solution

A variable flowpath casing with a smart structure that adjusts its surface to maintain optimal blade-tip-to-casing clearance through materials with different coefficients of thermal expansion, using passive and active clearance control systems to respond to temperature changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed casing is used, then manufacturing is simple, but blade tip clearance cannot be controlled under varying thermal conditions

Engineering Contradiction:

Improveblade tip clearance controlVSAvoidcasing structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by transforming the fixed casing into a variable flowpath casing that can dynamically adjust its internal geometry. The casing includes movable walls or segments that can change position in response to thermal conditions, allowing the flowpath area to vary and thereby control blade tip clearance dynamically rather than being fixed during operation

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by modifying the flowpath area parameter of the casing. By changing the cross-sectional area of the flowpath through movable components, the system alters the effective clearance between blade tips and casing, enabling adaptation to different thermal expansion conditions without changing the physical clearance dimensions directly

Inventive Principle:

Principle #35Parameter changes

2Reliability

If materials with different thermal expansion coefficients are used, then tip clearance can be compensated, but manufacturing precision requirements increase

Engineering Contradiction:

Improvetip clearance maintenanceVSAvoidclearance control precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent directly applies thermal expansion principles by incorporating materials with different coefficients of thermal expansion into the casing structure. These materials are strategically selected and positioned so that their differential expansion and contraction behaviors automatically compensate for blade tip clearance variations under different operating temperatures, reducing the need for high-precision manufacturing tolerances

Inventive Principle:

Principle #37Thermal expansion

3Device complexity

If passive clearance control is used, then device complexity is reduced, but responsiveness to rapid thermal changes is limited

Engineering Contradiction:

Improvecontrol systemVSAvoidthermal response speed

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The patent implements self-service through passive clearance control mechanisms where the casing structure automatically adjusts its own geometry in response to thermal conditions without requiring external control systems. The differential thermal expansion of materials and the elastic deformation of casing components create self-regulating behavior that responds to thermal changes inherently, eliminating the need for sensors, actuators, or control algorithms while maintaining adequate response speed for typical operating variations

Inventive Principle:

Principle #25Self-service

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 solution effectively maintains desired tip clearances, preventing blade rubbing and performance losses, enhancing turbine efficiency and stability by dynamically adjusting to thermal changes.

Implementation Method 1

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20250237150A1Variable flowpath casings for blade tip clearance control

Publication Date: 2025.07.24 GENERAL ELECTRIC CO

AI summary

Disclosed herein are example variable flowpath casings for blade tip clearance control. An example casing for a turbine engine includes an annular substrate extending along an axial direction, the annular substrate including a first surface and a second surface that is radially inward relative to the first surface; an actuator structure coupled to the second surface of the annular substrate; and a smart structure cantilevered from the second surface of the annular substrate, the smart structure including: a support structure, a first region of the support structure coupled to the second surface of the annular substrate, a second region of the support structure coupled to the actuator structure; and a radially inward surface defining a variable surface, the support structure to move the variable surface in a radial direction.