Curvi-linear Trailing Edge Profile for Rotor Blade Noise Reduction
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Solution Overview
Problem
Existing rotor blade tracking wedges, while effective in reducing vibrations, often generate undesirable acoustic noise due to turbulent vortices and pressure fluctuations, particularly with linear and triangular geometries, which are not adequately addressed by current serration designs.
Innovation Solution
A curvi-linear trailing edge profile with an acute return angle or curved rear edge is used in attachable and detachable wedges that extend beyond the rotor chord length to minimize turbulence and noise, adhered to the top, bottom, or trailing end of the rotor blade, modifying the aerodynamic properties to reduce vortex shedding and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear or triangular wedge profiles are used for vibration reduction, then dynamic vibration control is improved, but acoustic noise increases due to turbulent vortices and pressure fluctuations
Solution Approach 1:
The patent applies curvature to the trailing edge of the wedge profile, replacing the traditional linear or triangular sharp trailing edge with a curved geometry. This curvature modifies the flow separation characteristics, reducing the intensity of vortex shedding and pressure fluctuations that generate acoustic noise, while maintaining the vibration reduction function of the wedge profile
Solution Approach 2:
The patent modifies only the trailing edge region of the wedge profile while maintaining the overall wedge geometry for vibration control. The curved trailing edge creates a localized change in flow characteristics without altering the global structural function, allowing vibration reduction to be preserved while acoustic noise is reduced in the specific region of interest
2Object-generated harmful factors
If serrations are added to reduce turbulence, then acoustic noise is reduced, but device complexity increases
Solution Approach 1:
The patent uses a simple curved trailing edge geometry instead of complex serrations or multiple geometric features. This single curvature modification achieves noise reduction through modified flow separation and reduced vortex shedding, avoiding the need for additional complex structural elements while maintaining effectiveness
3Object-generated harmful factors
If wedge profile extends beyond rotor chord length, then turbulence is minimized and noise reduced, but blade performance may be impacted
Solution Approach 1:
The curved trailing edge allows the wedge profile to extend beyond the rotor chord length while managing the flow characteristics more effectively. The curvature ensures that the extended portion does not create additional turbulence or drag penalties, allowing performance to be maintained even with the extended geometry that provides noise reduction benefits
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
The solution effectively reduces acoustic noise and vibration while maintaining blade performance, allowing for field adjustments without increasing decibel levels, by altering the aerodynamic properties and flow patterns to minimize resonance zones and vortices.
Implementation Method 1
turbulent vortices and pressure fluctuations
Implementation Method 2
blunt trailing edge noise (generated from von Karman vortex shedding over the blunt trailing edge)
Data Source
AI summary
This invention provides convenient airframe vibration, tracking, and acoustic improvements of a helicopter rotor blade by use of a profile system. The profile system is designed to minimize acoustic disturbances as air passes the airfoil. The profile may be attached through an adhesive system that allows convenient removal and relocation for use by the helicopter manufacturer or by the helicopter operator in a field environment.