Propulsion Hot Section Coupling Structure for Thermal Relaxation

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Solution Overview

Problem

Propulsion system hot section coupling structures, such as afterburning gas turbine engines, face issues with mechanical fastener loosening and failure due to thermal relaxation and exposure to combustion gases, leading to structural deterioration and failure from undesired displacement.

Innovation Solution

A coupling method and structure that uses a housing with a retaining rod and groove, a structural member, and a retaining plate to create a load path and restrict displacement, employing a mechanical fastener to secure the assembly between the housing, inner casing, and outer casing, thereby maintaining clamping force and preventing structural failure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If mechanical fasteners are used to secure the coupling structure in hot section, then the structure can be assembled and disassembled, but the fasteners loosen and fail due to thermal relaxation and combustion gas exposure

Engineering Contradiction:

Improveseparable coupling capabilityVSAvoidfastener retention under thermal load

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

A thermal barrier coating is applied to the mechanical fasteners and coupling structure surfaces. This intermediary layer acts as a protective mediator between the fasteners and the harsh thermal environment (combustion gases at high temperature), preventing direct thermal exposure that causes fastener loosening and failure, while still allowing the fasteners to perform their securing function.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The coupling structure employs composite construction combining high-temperature resistant materials with the mechanical fastening system. The housing and structural members are made from materials with high creep strength and thermal stability, while the fasteners are designed as a composite system including thermal barriers and reinforcement elements, creating a multi-material solution that maintains integrity under thermal and mechanical loads.

Inventive Principle:

Principle #40Composite materials

2Productivity

If the coupling structure is exposed to combustion gases in hot section, then the propulsion system can operate, but thermal relaxation causes structural deterioration and fastener failure

Engineering Contradiction:

Improvepropulsion system operationVSAvoidcoupling structure service life

Core Design Contradiction:

ProductivityVSDuration of action of stationary object

Solution Approach 1:

The thermal barrier coating converts the harmful effect of high-temperature combustion gases into a beneficial protective layer. The coating thickness and material properties are designed to provide optimal thermal protection, transforming the harsh thermal environment from a cause of deterioration into a controlled condition that maintains structural integrity over extended service life.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The design changes critical parameters of the coupling structure including material selection (high-temperature alloys), geometric features (reinforced fastener holes, optimized wall thickness), and surface treatment (thermal barrier coating). These parameter modifications enable the structure to withstand thermal relaxation and maintain its service life under continuous operation in the hot section.

Inventive Principle:

Principle #35Parameter changes

3Stability of the object's composition

If the structural member is retained between housing and retaining plate, then displacement is restricted, but clamping force is lost over time due to thermal effects

Engineering Contradiction:

Improvestructural position stabilityVSAvoidclamping force retention

Core Design Contradiction:

Stability of the object's compositionVSForce

Solution Approach 1:

The thermal barrier coating is applied preliminarily to the fasteners and contact surfaces before assembly. This pre-protection ensures that when the structure is subjected to thermal loads during operation, the clamping force is maintained longer because the thermal degradation of the fastening interface is prevented in advance, thereby preserving both stability and force retention.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10563868B2Coupling method and structure for a propulsion system hot section

Publication Date: 2020.02.18 GENERAL ELECTRIC CO

AI summary

The present disclosure is directed to a method and structure of coupling a flameholder assembly to a hot section of a propulsion system, such as an afterburning exhaust section. The propulsion system includes an outer casing and an inner casing defining a flameholder assembly disposed radially within the outer casing. The method includes providing a housing defining a retaining rod and groove into which a structural member attaches; providing a retaining plate defining an opening through which the structural member is extended; coupling the structural member to the retaining rod of the housing and the outer casing of the propulsion system; and coupling the retaining plate to the housing and the inner casing of the propulsion system such that the structural member is retained between the housing and the retaining plate.