Annular Combustion Chamber Elastic Hinge Vibration Damping

Solution Overview

Problem

The existing annular combustion chamber in turbomachines experiences vibrations during operation, leading to misalignment of fuel injectors and reduced chamber life due to single downstream fixing, which requires a compromise between flange rigidity and flexibility to accommodate pressure and temperature variations.

Innovation Solution

The implementation of elastically deformable bridges formed by curved leaf springs connecting the combustion chamber to internal and external casings, allowing for vibration absorption and relative displacements, while maintaining mechanical and aerodynamic integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If the downstream fixing flanges are made rigid to limit chamber vibrations, then the chamber stability improves, but the ability to accommodate pressure and temperature variations deteriorates

Engineering Contradiction:

Improvechamber stabilityVSAvoidaccommodation of pressure and temperature variations

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The fixing system is divided into two independent parts: rigid downstream flanges for stability and elastic bridges at the upstream end for adaptability. This segmentation allows each part to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Elastic bridges act as intermediary elements between the chamber and the rigid downstream flanges. These bridges absorb vibrations while allowing the downstream flanges to remain rigid, mediating between the conflicting requirements of stability and adaptability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the downstream flanges are softened to allow relative displacements of casings and chamber walls, then the adaptability to pressure and temperature variations improves, but the chamber vibrations increase

Engineering Contradiction:

Improverelative displacements of casings and chamber wallsVSAvoidchamber vibrations

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The fixing system is divided into two independent parts: rigid downstream flanges for stability and elastic bridges at the upstream end for adaptability. This segmentation allows each part to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different parts of the chamber have different fixing characteristics: the downstream end has rigid flanges for stability, while the upstream end has elastic bridges for adaptability. This local differentiation allows each region to have the properties it needs for its specific function.

Inventive Principle:

Principle #3Local quality

3Device complexity

If single downstream fixing is used to simplify the structure, then the device complexity decreases, but the chamber vibrations and injector misalignment increase

Engineering Contradiction:

Improvefixing structure complexityVSAvoidchamber vibrations

Core Design Contradiction:

Device complexityVSStability of the object's composition

Solution Approach 1:

The fixing system is divided into two independent parts: rigid downstream flanges for stability and elastic bridges at the upstream end for adaptability. This segmentation allows each part to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of completely redesigning the entire fixing system, the invention adds elastic bridges at the upstream end while keeping the existing downstream flanges. This partial action provides the needed vibration damping without requiring complete system redesign.

Inventive Principle:

Principle #16Partial or excessive action

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 solution effectively dampens vibrations, increases the life of the combustion chamber by softening downstream flanges, and simplifies maintenance with quick assembly and disassembly, while maintaining air flow and mechanical compatibility.

Implementation Method 1

elastically deformable bridges each formed of a curved leaf spring

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Implementation Method 2

The elastically deformable support or suspension bridges of the upstream end of the chamber make it possible to absorb and dampen the vibrations generated by the turbomachine in operation

Methodology Applied

Scientific EffectVibration damping: Damping

Data Source

PatentEP2031303B1Turbomachine with annular combustion chamber

Publication Date: 2018.06.13 SAFRAN AIRCRAFT ENGINES SAS

Figure 1
Figure 2~3
Figure 4~7

AI summary

The turbomachine has an annular chamber base (28) crossed by a fuel injection unit (42) and fixed to internal and external cases (14, 18) by respective internal and external walls (24, 26). An annular combustion chamber (46) has an upstream end connected to one of the cases by elastically deformable external and internal hinge plates (48, 49). Each plate is formed of bend spring plate extending circumferentially and distributed around the chamber. The plates are fixed on one of the cases by bolting and radially supported on the chamber base.