Compliant Fastener Units for Gas Turbine Exhaust Nozzle Thermal Expansion

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Solution Overview

Problem

Gas turbine engine exhaust nozzles face challenges in supporting components due to high temperatures, requiring innovative designs that allow for thermal expansion and contraction while maintaining structural integrity and aerodynamic efficiency.

Innovation Solution

The design incorporates an outer shroud, inner plug, and support vanes with fastener units that include anchor and expansion-permissive fastener units, allowing the outer shells to thermally expand and contract relative to the underlying frames, ensuring the exhaust nozzle components can adapt to temperature changes without adverse stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If rigid fastening is used to maintain structural integrity, then strength is improved, but thermal expansion freedom deteriorates

Engineering Contradiction:

Improvestructural integrityVSAvoidthermal expansion freedom

Core Design Contradiction:

StrengthVSAdaptability or versatility

Solution Approach 1:

The exhaust nozzle is divided into multiple segments (outer shroud, inner plug, support vanes) that can independently expand and contract. The segmentation allows each component to accommodate thermal expansion separately while maintaining overall structural integrity through controlled connection points.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The fastener units incorporate slots that change their constraint parameters from fully rigid to selectively compliant. The slots allow movement in specific directions (radial expansion) while maintaining constraint in other directions (axial position), enabling the structure to adapt to thermal parameter changes.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If compliant fastening is used to allow thermal expansion, then adaptability is improved, but structural strength deteriorates

Engineering Contradiction:

Improvethermal expansion freedomVSAvoidstructural integrity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

Different regions of the exhaust nozzle have different fastening qualities. The outer shroud and inner plug use rigid fastening where structural strength is critical, while the support vanes use compliant fastening with slots where thermal expansion freedom is prioritized. This local differentiation resolves the contradiction by applying the appropriate fastening type to each specific location.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If rigid structure is used to maintain aerodynamic precision, then manufacturing precision is improved, but thermal stress increases

Engineering Contradiction:

Improveaerodynamic precisionVSAvoidthermal stress

Core Design Contradiction:

Manufacturing precisionVSStress or pressure

Solution Approach 1:

The exhaust nozzle transitions from a static rigid structure to a dynamic structure that can adapt its shape in response to thermal conditions. The compliant fastener units enable controlled movement and deformation, allowing the aerodynamic surfaces to maintain precision under varying thermal loads rather than experiencing accumulated stress.

Inventive Principle:

Principle #15Dynamics

4Stress or pressure

If compliant structure is used to reduce thermal stress, then stress resistance is improved, but aerodynamic precision deteriorates

Engineering Contradiction:

Improvethermal stressVSAvoidaerodynamic precision

Core Design Contradiction:

Stress or pressureVSManufacturing precision

Solution Approach 1:

The compliant structure is segmented into discrete components (outer shroud, inner plug, support vanes) with controlled degrees of freedom. This segmentation ensures that thermal compliance occurs in specific directions and locations, while other regions maintain rigid aerodynamic surfaces, thus preserving overall aerodynamic precision while reducing thermal stress.

Inventive Principle:

Principle #1Segmentation

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 design enables the exhaust nozzle to efficiently manage thermal expansion and contraction, reducing stress on components and optimizing flow path area for improved engine efficiency and noise reduction, while maintaining structural integrity and aerodynamic performance.

Implementation Method 1

The plurality of fastener units may be configured to allow the outer plug shell to thermally expand and contract relative to the plug-support frame and to allow the outer vane shell to thermally expand and contract relative to the vane-support frame

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

the fastener of the expansion-permissive fastener unit is configured to translate through the longitudinal slot as the temperature of the exhaust nozzle changes to allow the outer plug shell and the outer vane shell to thermally expand and contract

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS11326551B1Exhaust nozzle having a compliant shell for a gas turbine engine

Publication Date: 2022.05.10 ROLLS ROYCE NORTH AMERICAN TECHNOLOGIES INC

AI summary

An exhaust nozzle for use with a gas turbine engine includes an outer shroud, an inner plug spaced radially apart from the outer shroud, and at least one support vane that is coupled to the outer shroud. The outer shroud and the inner plug cooperate to provide an exhaust nozzle flow path therebetween. The at least one support vane interconnects the outer shroud and the inner plug to support the inner plug in the exhaust nozzle flow path.