Turbomachine Combustion Chamber Upstream Suspension

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Solution Overview

Problem

The existing methods for mounting annular combustion chambers in turbomachines, particularly convergent ones, lead to inaccuracies in injector positioning due to manufacturing and assembly tolerances, resulting in suboptimal combustion and decreased aerodynamic performance, as well as increased mass and cost due to the need for larger downstream casing diameters.

Innovation Solution

The combustion chamber is suspended from the outer casing using articulated connecting rods that attach to the upstream end, allowing for precise alignment and reducing radial stresses, while flexible connections at the downstream end minimize vibrations and weight, enabling upstream mounting without enlarging the casing diameter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the combustion chamber is mounted downstream in the outer casing, then the assembly is easier to carry out, but the downstream diameter of the outer casing must be increased, leading to increased radial bulk, mass, and cost

Engineering Contradiction:

Improveease of assemblyVSAvoidmass of outer casing

Core Design Contradiction:

Ease of manufactureVSWeight of stationary object

Solution Approach 1:

The patent inverts the conventional mounting approach by suspending the combustion chamber from the upstream end of the outer casing rather than mounting it downstream. This inversion allows the chamber to be positioned without increasing the downstream diameter of the outer casing, thereby reducing radial bulk and mass while maintaining ease of assembly through the suspension mechanism

Inventive Principle:

Principle #13The other way round (Inversion)

2Ease of manufacture

If the combustion chamber is mounted downstream in the outer casing, then the assembly is easier to carry out, but the alignment of the outer casing of the chamber and the outer casing of the turbine section deteriorates, decreasing aerodynamic performance

Engineering Contradiction:

Improveease of assemblyVSAvoidaerodynamic performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

By suspending the combustion chamber from the upstream end rather than mounting it downstream, the patent maintains proper alignment between the outer casing of the chamber and the outer casing of the turbine section. This upstream suspension approach prevents the misalignment that would occur with downstream mounting, thereby preserving aerodynamic performance while still allowing for straightforward assembly

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The suspension means act as an intermediary mechanism between the combustion chamber and the outer casing. This intermediary suspension system from the upstream end enables precise positioning and alignment of the chamber with the turbine section casing, maintaining aerodynamic performance without the complications of downstream mounting

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If successive fixings of the walls and flanges are used to mount the chamber, then the chamber can be securely attached, but the accumulation of tolerances leads to inaccuracy in positioning the chamber and aligning the injectors

Engineering Contradiction:

Improvesecure attachmentVSAvoidpositioning accuracy of chamber and injectors

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The patent extracts the problematic multiple fixing operations (fixing walls then fixing flanges) and replaces them with a single upstream suspension mechanism. This elimination of successive fixings prevents the accumulation of tolerances that would otherwise occur through multiple assembly steps, thereby maintaining both secure attachment and precise positioning of the chamber and injectors

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The upstream suspension means serve as an intermediary mechanism that directly positions the combustion chamber without requiring multiple intermediate fixings. This single suspension point establishes the chamber position and injector alignment simultaneously, preventing tolerance accumulation while ensuring secure attachment

Inventive Principle:

Principle #24Intermediary (Mediator)

4Manufacturing precision

If the chamber is suspended from the outer casing at the upstream end, then the alignment and combustion are optimized, but the connecting rod may interfere with the bypass airflow

Engineering Contradiction:

Improvealignment precision of injectorsVSAvoidairflow disturbance

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by making the connecting rod slender and positioning it in a specific location where it minimizes interference with bypass airflow. The rod's cross-sectional area and placement are optimized locally to maintain injector alignment precision while reducing aerodynamic disturbance to acceptable levels

Inventive Principle:

Principle #3Local quality

Data Source

PatentEP2019264B1Combustion chamber of a turbomachine

Publication Date: 2016.04.13 SN DETUDE & DE CONSTR DE MOTEURS DAVIATION (S N E C M A)

Figure 1~2
Figure 3~4
Figure 5~8

AI summary

Turbomachine comprising an annular combustion chamber (48), having two radially internal (24) and radially external (26) walls of revolution, connected at their upstream ends by an annular chamber bottom (24) equipped with fuel injection means, characterized in that it comprises means for suspending the upstream end of the combustion chamber (48) to an external casing (18).