Stator Vane Local Geometry Reworking for Brazed Joint Stress Reduction

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Solution Overview

Problem

The existing methods for reworking the geometry of stator vanes in turbomachines to reduce stress levels in the brazed joint between the vane and the outer shroud are cumbersome, costly, and require multiple iterations between aerodynamic and mechanical engineering, altering the aerodynamic profile and necessitating a complete change of the vane.

Innovation Solution

A local reworking of the stator section geometry, where the radius of curvature of the trailing edge increases progressively in a transition zone and the thickness of the vane increases on the pressure face side, allowing for reduced stress without affecting the aerodynamic profile, and enabling the stator section to be interchangeable with existing parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If the radius of curvature of the trailing edge is increased to reduce stress in the brazed joint, then the stress level is reduced, but the aerodynamic profile is altered requiring recalculation and iteration

Engineering Contradiction:

Improvestress level in brazed jointVSAvoidaerodynamic profile

Core Design Contradiction:

Stress or pressureVSShape

Solution Approach 1:

The patent applies local quality by increasing the radius of curvature of the trailing edge only in a localized zone near the brazed joint, while maintaining the original aerodynamic profile in the rest of the vane. This localized modification reduces stress at the critical joint area without altering the overall aerodynamic characteristics, eliminating the need for profile recalculation and iteration.

Inventive Principle:

Principle #3Local quality

2Stress or pressure

If the vane thickness is increased to reduce stress in the brazed joint, then the stress level is reduced, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improvestress level in brazed jointVSAvoidmanufacturing complexity

Core Design Contradiction:

Stress or pressureVSEase of manufacture

Solution Approach 1:

The patent implements local quality by increasing vane thickness only in a localized zone near the brazed joint rather than throughout the entire vane. This localized thickening reduces stress at the critical joint area while minimizing the amount of material added and manufacturing complexity, avoiding the need for complete vane redesign.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the vane into different zones: a first zone with the original aerodynamic profile and a second zone with increased thickness near the brazed joint. This segmentation allows the vane to have different properties in different areas, optimizing both aerodynamic performance and stress resistance without requiring complete redesign.

Inventive Principle:

Principle #1Segmentation

3Stress or pressure

If the vane geometry is completely reworked to reduce stress, then the stress level is reduced, but the time and cost for redesign and iteration increase

Engineering Contradiction:

Improvestress level in brazed jointVSAvoidredesign time

Core Design Contradiction:

Stress or pressureVSLoss of time

Solution Approach 1:

The patent applies local quality by making only localized modifications to the vane geometry near the brazed joint, rather than completely reworking the entire vane. This approach reduces stress at the critical area while avoiding extensive redesign time and costs associated with complete vane replacement and aerodynamic recalculation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent applies partial action by modifying only the portion of the vane that is necessary to reduce stress (the zone near the brazed joint) rather than modifying the entire vane. This partial modification achieves the stress reduction goal with minimal redesign effort and time investment.

Inventive Principle:

Principle #16Partial or excessive action

4Stress or pressure

If the vane geometry is reworked to reduce stress, then the stress level is reduced, but the number of iterations between aerodynamic and mechanical engineering increases

Engineering Contradiction:

Improvestress level in brazed jointVSAvoidnumber of iterations

Core Design Contradiction:

Stress or pressureVSDevice complexity

Solution Approach 1:

The patent applies local quality by modifying only the localized zone near the brazed joint, which eliminates the need for iterations between aerodynamic and mechanical engineering. Since the aerodynamic profile is unchanged in the majority of the vane, no recalculation is required, reducing device complexity to a single design iteration.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent segments the vane into a first zone with the original aerodynamic profile and a second zone with modified geometry near the brazed joint. This segmentation allows mechanical stress reduction without affecting aerodynamic calculations, eliminating the need for iterative coordination between different engineering disciplines.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7857584B2Stator vane with localized reworking of shape, stator section, compression stage, compressor and turbomachine comprising such a vane

Publication Date: 2010.12.28 SAFRAN AIRCRAFT ENGINES SAS

AI summary

The invention relates to a novel reworking of a geometric shape of a stator vane in order locally to reduce the stress levels. It proposes a novel type of stator section in which a local reworking of the geometry of the vanes has been performed, this reworking making it possible to reduce the level of stress in the brazed joint connecting the vane to its outer shroud without entailing further aerodynamic engineering. To do that, the invention consists in a progressive and localized increase in the radius at the trailing edge combined with a progressive increase in the thickness of the vane.