Flow Splitter Serration Profile for Turbine Engine Noise Reduction
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Solution Overview
Problem
Aero-acoustic management in aerodynamic profiled structures, such as turbomachine blades and aircraft wings, faces challenges in reducing noise while minimizing impact on aerodynamic properties, as existing serration profiles affect airflow and lead to significant noise emission and aerodynamic losses.
Innovation Solution
The introduction of a serrated profile with individually inclined teeth and angularly offset depressions, where teeth are oriented along the camber line of guide vanes and depressions are positioned between successive guide vanes, allowing for adaptive inclination based on engine speed and airflow complexity, with wavy or corrugated shapes to reduce mechanical stress and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If serration profiles are used to reduce broadband noise, then noise levels are reduced, but aerodynamic properties are significantly affected
Solution Approach 1:
The patent applies different geometric characteristics to different parts of the serration profile. The teeth are inclined at specific angles relative to the airflow direction, and the depressions have varying depths and orientations. This local differentiation allows the profile to reduce noise through scattering while minimizing disruption to the overall airflow and boundary layer, thereby reducing aerodynamic losses compared to uniform serration designs.
Solution Approach 2:
The serration profile features asymmetric tooth geometry where the inclined faces of the teeth are not symmetrical with respect to the airflow direction. The teeth have different upstream and downstream slopes, and the depressions are positioned asymmetrically along the leading and trailing edges. This asymmetry is optimized to scatter noise effectively while maintaining favorable pressure gradients and reducing flow separation, thus preserving aerodynamic performance.
2Length of moving object
If fan diameter is increased and suspension pod length is reduced, then distance between fan and inlet guide vanes is reduced, but noise from wake interaction increases
Solution Approach 1:
The serrated inlet guide vane leading edges act as intermediary structures between the fan wake and the compressor inlet. These serrations modify the interaction by scattering the wake turbulence and reducing the intensity of unsteady pressure fluctuations that would otherwise propagate into the compressor. This intermediary action allows for reduced spacing while maintaining acceptable noise levels.
Solution Approach 2:
The patent introduces serrations that add a third-dimensional geometric feature to the otherwise two-dimensional inlet guide vane leading edges. This dimensional addition creates multiple scattering centers along the spanwise direction, effectively distributing and reducing the noise generated by wake interaction in the radial-axial plane, thereby mitigating the noise issue caused by reduced spacing.
3Object-affected harmful factors
If teeth of serrated profile are inclined to face oblique airflow, then acoustic noise levels are reduced, but structural complexity increases
Solution Approach 1:
The patent optimizes specific geometric parameters of the serration profile, including the inclination angle of the teeth (typically 15-45 degrees relative to the airflow direction), the depth and width ratios of the teeth, and the spacing between adjacent teeth. By carefully selecting and optimizing these parameters, the design achieves effective noise reduction through scattering while maintaining manufacturability and avoiding excessive geometric complexity.
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 reduces broadband noise and aerodynamic losses by optimizing the serration profile to align with airflow dynamics, enhancing the mechanical simplicity and service life of the structures while adapting to varying airflow conditions.
Implementation Method 1
Although 'serration' profiles are capable of reducing the broadband noise emitted
Implementation Method 2
Aerodynamic properties (aerodynamic losses, lift, boundary layer stall, etc.) can therefore be significantly affected
Data Source
AI summary
An airflow profile structure having a leading and/or trailing edge profiled with a serrated profile. The serrated profile has a succession of teeth and depressions, characterized in that, along the leading and/or trailing edge, from a first location to a second location, the teeth of the serrated profile are individually inclined towards the second location.