Convex Gas Turbine Case With Tension Rods

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Solution Overview

Problem

Gas turbine engine cases often lack sufficient strength and stiffness, particularly in the axial direction, due to their design, which can lead to component damage under operational loads.

Innovation Solution

A convex case section with an intermediate portion having a larger radius than the upstream and downstream portions, combined with tension rods connecting these sections, enhances axial stiffness and structural support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the case is designed with a convex intermediate portion to accommodate a larger combustor section, then the combustor size is increased, but the axial stiffness of the case is reduced

Engineering Contradiction:
Improvecombustor section sizeVSAvoidaxial stiffness
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The case is divided into three distinct portions: upstream case portion, intermediate case portion, and downstream case portion. This segmentation allows each section to have optimized characteristics - the intermediate portion can be enlarged for combustor accommodation while the upstream and downstream portions maintain structural stiffness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different portions of the case have different radii tailored to their specific functional requirements. The intermediate case portion has a larger radius to accommodate the combustor, while the upstream and downstream portions have smaller radii to maintain axial stiffness and structural support.

Inventive Principle:
Principle #3Local quality

2Strength

If tension rods are added to increase axial stiffness, then the structural strength is improved, but the device complexity increases

Engineering Contradiction:
Improveaxial stiffnessVSAvoidnumber of components
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The axial stiffness function is extracted from the case structure itself and implemented separately through tension rods. This allows the case to be optimized for combustor accommodation while the tension rods provide the necessary axial stiffness, separating the two functional requirements.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Tension rods act as intermediary elements that connect the upstream and downstream case portions, providing the necessary axial stiffness without requiring the entire case structure to be overly complex or massive.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2938843B1Axial tension system for a gas turbine engine case
Publication Date: 2020.04.08 UNITED TECH CORP
  • EP2938843B1 patent drawingFigure 1A
  • EP2938843B1 patent drawingFigure 1B
  • EP2938843B1 patent drawingFigure 1C

AI summary

A gas turbine engine includes a convex case section. The convex case section includes an upstream case portion having a first radius, a downstream case portion having a second radius, and an intermediate case portion between the upstream case portion and the downstream case portion. The intermediate case portion has a third radius larger than the first radius and the second radius. A tension rod extends from the upstream case portion to the downstream case portion.