Turbomachine Diffuser Outer Casing Integration

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Solution Overview

Problem

The assembly of known turbomachine diffusers is challenging due to the difficulty in fixing the conical outer surface of the downstream part and the tendency of the outer shroud to slide, making it hard to secure properly by brazing or crimping.

Innovation Solution

The outer casing is used to form the outer wall of the downstream part, eliminating the need for an external ferrule and shroud, and providing a shoulder for correct positioning of the intermediate part, which simplifies assembly and reduces mass.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an outer shroud is used to surround the downstream part of the diffuser, then the diffuser structure is complete and functional, but the assembly becomes difficult due to the conical outer surface causing the shroud to slide and be hard to secure by brazing or crimping

Engineering Contradiction:

Improvestructural completenessVSAvoidassembly difficulty

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The outer casing is designed to directly form the outer wall of the downstream part, merging two previously separate components (outer casing and outer shroud) into one integrated structure. This eliminates the need for separate fixation operations and resolves the assembly difficulty caused by the conical surface.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The outer casing is given a dual function: it both surrounds the combustion chamber and downstream part, and simultaneously forms the outer wall of the downstream part itself. This multi-functionality eliminates the need for a separate outer shroud component.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If a separate outer shroud is used to delimit the gas stream externally, then the diffuser provides complete flow control, but the overall mass of the diffuser increases

Engineering Contradiction:

Improveflow control completenessVSAvoiddiffuser mass

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

By merging the outer casing and outer shroud into a single integrated structure, the total material required is reduced while maintaining the complete flow control function. The outer casing assumes both protective and flow-delimiting roles.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The outer casing performs multiple functions including structural support, flow path definition, and external flow delimitation, replacing what previously required separate components. This reduces overall mass while maintaining functional completeness.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If the downstream part is inclined with respect to the axis to direct gas towards the combustion chamber, then gas supply to the combustion chamber is improved, but the outer surface becomes conical making fixation of the outer shroud particularly difficult

Engineering Contradiction:

Improvegas supply efficiencyVSAvoidfixation difficulty

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The inclination of the downstream part is maintained to improve gas supply, but the separate outer shroud is eliminated and merged with the outer casing. This allows the conical geometry to be maintained for flow optimization while avoiding the fixation difficulties that would arise from trying to attach a separate shroud to it.

Inventive Principle:

Principle #5Merging (Combining)

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 configuration facilitates easier assembly, reduces the mass of the diffuser, and ensures proper alignment, while allowing for thermal expansion compensation to maintain secure contact between components during operation.

Implementation Method 1

These diffusion passages have a section which gradually increases from the inside to the outside in order to diffuse the flow of gas leaving the compressor

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

the outer casing forms the outer wall of the downstream part

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 3

a series of circularly spaced straightening vanes, making it possible to straighten the flow of gas and thus reduce the gyration of the flow of gas leaving the diffusion passages

Methodology Applied

Scientific EffectFlow straightening:

Data Source

PatentEP2026006B1Turbomachine with diffuser

Publication Date: 2017.03.15 SN DETUDE & DE CONSTR DE MOTEURS DAVIATION (S N E C M A)

AI summary

The turbomachine has an annular diffuser (20) to distribute a flow of gas e.g. air, from a high pressure centrifugal compressor (10) and direct the flow to an annular combustion chamber (40). The diffuser has a downstream part (25) including straightening vanes (26) that are not fixed with an outer casing (32). The casing externally surrounds the chamber and the part, and forms an inner wall of the part such that the casing externally delimits a gas flow stream in the part. The casing has a shoulder against which an outer downstream edge of an intermediate part (24) of the diffuser is locked.