Anti-Phase Rotor Blade Vortex Interaction for Noise Reduction
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Solution Overview
Problem
Conventional rotor designs for aircraft, such as helicopters and drones, face challenges with noise and vibration due to blade vortex shedding, leading to harmonic reinforcement and increased noise signatures.
Innovation Solution
The implementation of anti-phase blade vortex interaction designs, including non-planar trailing-edge and leading-edge shapes, asymmetric blade tips, and ducted rotor configurations with stationary vanes, to break up harmonic reinforcement and reduce noise through destructive interference of vortices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional rotor blade design is used, then rotor thrust is generated, but noise and vibration increase due to harmonic reinforcement of blade vortex shedding
Solution Approach 1:
The patent applies asymmetry by configuring rotor blades with different chord lengths, twist angles, or airfoil sections. This asymmetric design disrupts the periodic harmonic reinforcement of blade vortex shedding, reducing noise while maintaining thrust generation capability
Solution Approach 2:
The patent introduces spanwise varying geometry parameters along the rotor blade length, transforming a two-dimensional airfoil problem into a three-dimensional configuration. This dimensional change creates non-uniform vortex shedding patterns that reduce harmonic reinforcement and associated noise
2Productivity
If rotor speed is increased to improve productivity, then thrust increases, but noise and vibration from blade vortex shedding increase
Solution Approach 1:
By using rotor blades with asymmetric geometric configurations, the patent reduces the intensity of vortex shedding at higher rotation speeds, allowing increased productivity without proportional noise increase
Solution Approach 2:
The patent modifies geometric parameters such as chord distribution, twist angle, and airfoil shape to optimize the balance between thrust generation and noise reduction across different operating speeds
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 approach effectively reduces rotor noise and vibration by disrupting harmonic vortex structures, resulting in lower noise levels and increased thrust efficiency compared to conventional rotor designs.
Implementation Method 1
noise due to noise-induced shed vortices generated by rotor blades
Implementation Method 2
create non-planar shed vortices and break up harmonic reinforcement of said shed vortices
Implementation Method 3
incorporates anti-phase blade tips that create non-planar tip vortices and break up harmonic reinforcement of said tip vortices
Implementation Method 4
stationary vanes or struts are configured in a manner to break up harmonic excitation to the rotor
Implementation Method 5
the interior area of the duct at the area of the blade rotation is so designed in a manner to create a destructive rotor blade tip vortex interference
Data Source
AI summary
An anti-phase rotor system for an aircraft may include at least one rotor with at least two rotor blades. The aerodynamic profile of these two blades may be selected to create counteracting blade vortices to break up harmonic reinforcement due to the rotor blade passage. The aerodynamic profile may create a non-planar motion of one or more rotor blade passages, whereby the individual rotor blades are not co-planar during the rotation of said rotor. The rotor system may include a duct, which may include stationary vanes or struts configured in a manner so as to break up harmonic excitation to the rotor. The interior area of the duct at the area of the blade rotation may be designed in a manner so as to create a destructive rotor blade tip vortex interference.