Gas Turbine Diffuser Case Local Quality Stress Relief

Solution Overview

Problem

Gas turbine engine diffuser cases experience localized stress points due to thermal transients, reducing their useful life and increasing maintenance needs, particularly at attachment locations where high pressure compressor discharge air leaks and interacts with the diffuser section.

Innovation Solution

The inner diffuser case design incorporates a structural cone with strategically reduced wall thickness in specific regions to alleviate localized stresses, maintaining structural integrity and reducing weight, while ensuring flange engagement and rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the diffuser case wall thickness is increased to withstand thermal transient stresses, then the strength and durability are improved, but the weight increases

Engineering Contradiction:

Improvediffuser case strengthVSAvoiddiffuser case weight

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The diffuser case employs varying wall thickness throughout its structure, with thicker walls at locations experiencing higher thermal transient stresses and thinner walls where stresses are lower. This localized variation in material distribution optimizes strength where needed while minimizing unnecessary weight elsewhere in the structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The wall thickness parameter of the diffuser case is strategically modified across different regions to match the stress distribution pattern. By changing the thickness parameter locally rather than uniformly, the design achieves adequate strength protection against thermal transients while reducing overall weight compared to a uniformly thick design.

Inventive Principle:

Principle #35Parameter changes

2Weight of stationary object

If the diffuser case wall thickness is reduced to minimize weight, then the weight decreases, but the ability to withstand localized stresses deteriorates

Engineering Contradiction:

Improvediffuser case weightVSAvoiddiffuser case stress resistance

Core Design Contradiction:

Weight of stationary objectVSStrength

Solution Approach 1:

The diffuser case employs varying wall thickness throughout its structure, with thicker walls at locations experiencing higher thermal transient stresses and thinner walls where stresses are lower. This localized variation in material distribution optimizes strength where needed while minimizing unnecessary weight elsewhere in the structure.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The wall thickness parameter of the diffuser case is strategically modified across different regions to match the stress distribution pattern. By changing the thickness parameter locally rather than uniformly, the design achieves adequate strength protection against thermal transients while reducing overall weight compared to a uniformly thick design.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3066318B1Inner diffuser case for a gas turbine engine

Publication Date: 2023.06.21 RTX CORP

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AI summary

A combustor section of a gas turbine engine has a diffuser case with a structural cone having variable wall thicknesses strategically located for reducing localized stress in the cone.