Radial Position Control Assembly for Gas Turbine Engine

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Solution Overview

Problem

In gas turbine engines, thermal transients cause supported structures to move radially inward, leading to rub events due to inadequate radial clearances, which are enlarged to prevent such events but reduce efficiency during steady-state conditions.

Innovation Solution

A radial position control assembly with a support ring having a different coefficient of thermal expansion than the supported structure, maintaining clearance through a circumferential and radial gap, and a pin to isolate the support ring from loads, with optional cooling fluid regulation to manage clearance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If radial clearances are enlarged to prevent rub events during thermal transients, then reliability is improved, but efficiency deteriorates during steady-state conditions

Engineering Contradiction:

Improveprevention of rub eventsVSAvoidefficiency during cruise conditions

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The support ring is designed to dynamically adjust its radial position based on thermal conditions. During thermal transients, the support ring moves radially inward with the supported structure, maintaining optimal clearance. During steady-state conditions, the support ring stabilizes at a position that maintains efficient operation. This dynamic adaptation resolves the contradiction between reliability and efficiency by allowing clearance to vary with operating conditions rather than being fixed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The support ring is constructed from a material with a different coefficient of thermal expansion than the supported structure. This differential thermal expansion allows the support ring to move radially relative to the supported structure during temperature transients, maintaining optimal clearance. The material selection and dimensional design of the support ring enable it to expand and contract at different rates than the supported structure, automatically adjusting clearance to prevent rub events while maintaining efficiency during steady-state operation.

Inventive Principle:

Principle #37Thermal expansion

2Productivity

If a circumferentially continuous support ring is used to reduce clearances, then productivity is improved, but harmful factors increase due to undesired contact loads

Engineering Contradiction:

Improveclearance reductionVSAvoidcontact loads between support ring and support structure

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The support ring is segmented into multiple discrete elements rather than being a continuous structure. These segments are arranged circumferentially and can move independently relative to each other. This segmentation allows the support ring to maintain overall structural integrity and productivity benefits while reducing harmful contact loads, as the discrete segments can accommodate thermal expansion and contraction without generating excessive contact forces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The support ring incorporates flexible elements or thin-walled structures that can deform elastically under load. This flexibility allows the support ring to adapt to thermal transients and maintain optimal clearance while distributing contact loads across multiple flexible contact points rather than concentrating forces, thereby reducing harmful contact loads while maintaining productivity benefits.

Inventive Principle:

Principle #30Flexible shells and thin films

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

Maintains optimal radial clearance during thermal transients, preventing rub events while maintaining efficiency by dynamically adjusting the support ring's position relative to the supported structure.

Implementation Method 1

The supported structure and the support ring have different coefficients of thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10053999B2Radial position control of case supported structure with axial reaction member

Publication Date: 2018.08.21 RTX CORP

AI summary

A radial position control assembly for a gas turbine engine stage includes a case structure. A supported structure is operatively supported by the case structure. A support ring operatively supports the supported structure. The supported structure and the support ring have different coefficients of thermal expansion. A sealing structure is adjacent to the supported structure. The support ring maintains the supported structure relative to the sealing structure at a clearance during thermal transients based upon a circumferential gap between adjacent supported structure and based upon a radial gap between the support ring and the supported structure. A pin supports the supported structure relative to the case structure and is configured to isolate the support ring from loads on the supported structure.