Small Exit Duct Cooling for Reverse Flow Combustors

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Solution Overview

Problem

Reverse flow combustors in gas turbine engines face durability issues with small exit ducts due to their tight radius design, which limits air cooling and requires scrapping of entire components for replacement, leading to manufacturing challenges and lifecycle problems.

Innovation Solution

A reverse flow combustor design featuring a removably fastened small exit duct with an annular ring and integral cooling elements, such as pins and ribs, that increases the effective surface area for cooling impingement airflow, allowing for improved durability and maintenance without disassembling the entire combustor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If ductile sheet metal is used to form the small exit duct to overcome manufacturing challenges, then ease of manufacture is improved, but durability and lifecycle are worsened

Engineering Contradiction:

Improveease of manufactureVSAvoiddurability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The small exit duct is segmented into modular components that can be independently manufactured and assembled. This allows the use of durable materials and manufacturing processes for each segment while maintaining overall ease of manufacture through standardized connection interfaces.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The small exit duct employs composite material construction, combining ductile sheet metal for structural flexibility with durable coatings or layered materials that enhance wear resistance and lifecycle, thus resolving the contradiction between ease of manufacture and durability.

Inventive Principle:

Principle #40Composite materials

2Strength

If the small exit duct is integrally formed with or welded to the liners, then structural strength is improved, but ease of repair and maintenance are worsened

Engineering Contradiction:

Improvestructural strengthVSAvoidease of repair

Core Design Contradiction:

StrengthVSEase of repair

Solution Approach 1:

The small exit duct is designed as a separable module with standardized connection interfaces to the liners, maintaining structural strength through proper joining mechanisms while enabling independent removal and replacement for maintenance without affecting other combustor components.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The design incorporates pre-configured connection and disconnection features that allow for rapid assembly and maintenance operations, reducing the time and complexity of repair while preserving structural integrity during operation.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If the tight radius bend geometry is used in the small exit duct, then the reverse flow function is improved, but the cooling surface area is reduced

Engineering Contradiction:

Improvereverse flow functionVSAvoidcooling surface area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The small exit duct incorporates three-dimensional cooling features such as ribs, fins, or internally cooled passages that add cooling surface area in the radial and thickness dimensions without increasing the overall footprint or compromising the tight radius bend geometry required for reverse flow function.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Cooling channels and surface enhancements are nested within the walls and structure of the small exit duct, providing additional cooling surface area without increasing the external dimensions or interfering with the tight radius bend configuration needed for effective reverse flow.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 design enhances the durability of the small exit duct by increasing cooling surface area and enables easy replacement of the small exit duct without damaging other combustor components, improving maintenance efficiency and extending the lifecycle of the gas turbine engine.

Implementation Method 1

the cooling elements increasing the effective surface area of the inner surface of the annular ring of the small exit duct which is adapted to be cooled by a cooling impingement airflow provided by the gas turbine engine

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS10527288B2Small exit duct for a reverse flow combustor with integrated cooling elements

Publication Date: 2020.01.07 PRATT & WHITNEY CANADA CORP

AI summary

The described reverse flow combustor of a gas turbine engine includes inner and outer combustor liners defining a combustor chamber therewithin. A large exit duct and a small exit duct are disposed at downstream ends of the outer and inner liner respectively. The small exit duct includes an annular ring removably mounted to a support element of the gas turbine engine and includes a plurality of cooling elements integrally formed with the annular ring and projecting therefrom into impingement airflow. The cooling elements increase the effective surface area of the inner surface of the annular ring, which is adapted to be cooled by the impingement airflow.