Outlet Guide Vane Spacing for Turbofan Tonal Noise Reduction

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Solution Overview

Problem

Existing turbofan engines generate significant noise due to fan-OGV interaction noise, which includes tonal and broadband noise components, and existing solutions do not effectively address both types independently.

Innovation Solution

Modifying the circumferential spacing of outlet guide vanes relative to a notionally uniform spacing to reduce tonal noise, and locally changing vane spacing to target noise reduction at specific azimuthal locations, without altering the total number of vanes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If uniform circumferential spacing of outlet guide vanes is used, then manufacturing and installation are simplified, but tonal noise radiation to sensitive areas increases

Engineering Contradiction:

Improveease of manufactureVSAvoidnoise radiation

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by varying the circumferential spacing of outlet guide vanes at specific locations rather than using uniform spacing throughout. The spacing is modified in targeted azimuthal regions to reduce tonal noise radiation to sensitive areas while maintaining uniform spacing in other regions, thus addressing noise problems locally without complicating the entire assembly.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces asymmetry by deliberately creating non-uniform circumferential spacing patterns among the outlet guide vanes. Instead of symmetric uniform distribution, the spacing is asymmetrically modified in specific azimuthal locations to target noise radiation pathways, breaking the symmetry that causes tonal noise while maintaining overall functional performance.

Inventive Principle:

Principle #4Asymmetry

2Object-affected harmful factors

If nonuniform circumferential spacing of outlet guide vanes is implemented, then tonal noise radiation is reduced, but manufacturing precision and installation complexity increase

Engineering Contradiction:

Improvenoise radiationVSAvoidmanufacturing precision

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The non-uniform spacing modification is applied locally at specific azimuthal positions rather than uniformly across all vanes. This localized approach concentrates the precision requirements only where noise reduction is needed, rather than demanding high precision throughout the entire assembly, thus reducing the overall manufacturing precision burden.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial modification of vane spacing rather than complete non-uniform spacing across all vanes. By applying spacing modifications to only certain vanes or regions where noise radiation is most problematic, the solution achieves noise reduction with reduced manufacturing precision requirements compared to implementing non-uniform spacing universally.

Inventive Principle:

Principle #16Partial or excessive action

3Object-affected harmful factors

If local changes in vane spacing are made, then noise reduction at specific azimuthal locations is achieved, but device complexity increases

Engineering Contradiction:

Improvenoise radiationVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Local changes in vane spacing are implemented only at specific azimuthal locations where noise radiation to sensitive areas occurs, rather than modifying the entire vane assembly. This localized modification approach reduces device complexity by limiting the scope of changes to only the necessary regions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The outlet guide vane assembly is segmented into different regions with different spacing characteristics. Uniform spacing is maintained in regions where noise is not a problem, while non-uniform spacing is applied only in specific segments where noise reduction is needed, thus managing device complexity through spatial segmentation.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12492642B2Outlet guide vane assembly for a turbofan engine

Publication Date: 2025.12.09 GENERAL ELECTRIC CO

AI summary

A turbofan engine defining a circumferential direction is provided. The turbofan engine includes: a turbomachine, the turbomachine defining a pylon attachment location along the circumferential direction; an unducted rotor assembly drivingly coupled to the turbomachine, the unducted rotor assembly including a plurality of unducted rotor blades; and a plurality of outlet guide vanes positioned downstream of the plurality of unducted rotor blades, the plurality of outlet guide vanes including NOGV number of outlet guide vanes, the plurality of outlet guide vanes including a first outlet guide vane and a second outlet guide vane adjacent the first outlet guide vane, the first and second outlet guide vanes defining a gap spacing greater than 360 degrees divided by NOGV, and the pylon attachment location positioned outside of between the first and second outlet guide vanes along the circumferential direction.