Airfoil Tip Profile Reducing Slope for Noise Reduction

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Solution Overview

Problem

Aerodynamic noise and aeromechanical loading in turbomachinery applications, such as unducted contra-rotating engines, are significant due to impinging wakes and vortices from upstream airfoils, which current methods attempt to mitigate by increasing distance, but this compromises engine efficiency and performance.

Innovation Solution

The airfoil design incorporates a tip profile with a reducing slope extending from the leading edge, configured to minimize high unsteady pressure near the tip portion, reducing noise and aeromechanical loading without increasing engine size, weight, or cost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If the distance between upstream object and downstream airfoil is increased to reduce noise, then aerodynamic noise is reduced, but engine size, weight, and cost increase

Engineering Contradiction:

Improveaerodynamic noiseVSAvoidengine weight

Core Design Contradiction:

Object-affected harmful factorsVSWeight of moving object

Solution Approach 1:

The tip profile modifies only the local geometry at the airfoil tip region while maintaining the overall airfoil structure. The reducing slope is applied specifically to the tip portion (spanwise extent of 0.8 to 1.0) to reduce unsteady pressure and noise without requiring changes to the entire engine structure, thus avoiding weight and size increases.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of increasing distance between airfoils to reduce noise interaction, this invention inverts the approach by modifying the tip geometry to actively reduce the unsteady pressure that causes noise. The reducing slope works opposite to the conventional approach of increasing separation distance.

Inventive Principle:

Principle #13The other way round (Inversion)

2Object-affected harmful factors

If the distance between upstream object and downstream airfoil is increased to reduce noise, then aerodynamic noise is reduced, but engine size increases

Engineering Contradiction:

Improveaerodynamic noiseVSAvoidengine size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The noise reduction is achieved through localized modification of the tip profile geometry rather than increasing the overall engine dimensions. The reducing slope is confined to the tip region, allowing the engine to maintain compact size while reducing noise from wake impingement.

Inventive Principle:

Principle #3Local quality

3Object-affected harmful factors

If the distance between upstream object and downstream airfoil is increased to reduce noise, then aerodynamic noise is reduced, but manufacturing cost increases

Engineering Contradiction:

Improveaerodynamic noiseVSAvoidmanufacturing cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The tip profile modification is a localized geometric change that can be integrated into existing airfoil manufacturing processes. By modifying only the tip region rather than the entire airfoil or engine structure, manufacturing complexity and cost are minimized while achieving noise reduction.

Inventive Principle:

Principle #3Local quality

4Object-affected harmful factors

If the distance between upstream object and downstream airfoil is increased to reduce noise, then aerodynamic noise is reduced, but engine efficiency and performance decrease

Engineering Contradiction:

Improveaerodynamic noiseVSAvoidengine efficiency

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

Rather than increasing distance to reduce noise (which would hurt performance), this invention inverts the approach by modifying tip geometry to reduce the unsteady pressure source itself. This maintains optimal airfoil spacing for efficiency while reducing noise from wake-airfoil interaction.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The tip profile parameters (reducing slope, spanwise extent, chordwise position) are optimized to reduce unsteady pressure and noise while maintaining or enhancing aerodynamic performance. The parameter changes are tailored to improve both noise characteristics and flow characteristics at the tip region.

Inventive Principle:

Principle #35Parameter changes

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 design effectively reduces open rotor noise and aeromechanical loading, maintaining performance and efficiency while adhering to noise regulations, without the need for increased axial separation or weight, thus offering an alternative to traditional noise reduction methods.

Implementation Method 1

a tip profile defining a reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length, wherein the tip profile is configured to reduce high unsteady pressure near the tip portion of the airfoil

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentUS9102397B2Airfoils including tip profile for noise reduction and method for fabricating same

Publication Date: 2015.08.11 GENERAL ELECTRIC CO

AI summary

An airfoil, a fan assembly and an unducted contra-rotating fan engine include fabricating at least one airfoil including a suction and a pressure side coupled together at a leading and a trailing edge and extending therebetween. The airfoil includes a plurality of chord sections having a chord length. The airfoil including a tip profile defining a reducing slope extending from the leading edge at the tip portion along at least a portion of the chord length. The tip profile is configured to reduce the high unsteady pressure near the tip portion of the airfoil.