Rotating Speaker Array for Rotor Blade-Tip Noise Reduction
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Solution Overview
Problem
There is no established method for active noise control for blade-tip noise caused by the rotation of a rotor, which is a significant challenge in reducing noise in devices like helicopters and wind turbines.
Innovation Solution
A noise reduction device comprising speakers and microphones arranged around a rotor, with a processing circuit that generates control signals to emit sound waves that counteract the blade-tip noise, based on microphone signals, rotation speed, and noise phase, effectively minimizing acoustic power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If active noise control is applied using conventional speaker arrangements, then noise reduction can be achieved in stationary scenarios, but the control effect deteriorates when the rotor rotates due to the time-varying nature of blade-tip noise
Solution Approach 1:
The patent applies dynamics by making the speaker arrangement rotate synchronously with the rotor at the same rotational speed. This dynamic adaptation allows the speakers to maintain a consistent spatial relationship with the rotating blades, enabling effective active noise control of the time-varying blade-tip noise that stationary speakers cannot achieve.
2Object-generated harmful factors
If speakers are arranged in a fixed position around the rotor, then the device structure is simple, but the noise control effectiveness decreases due to the rotating nature of the noise source
Solution Approach 1:
The patent merges the speaker arrangement system with the rotor system by making them rotate together at the same speed. This combining of functions allows the noise control system to adapt to the rotating noise source without requiring complex independent control mechanisms, as the rotational synchronization naturally maintains optimal positioning.
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 achieves significant reduction in acoustic power, improving the control effect over blade-tip noise, enhancing the operational efficiency and reducing noise pollution in rotor-based devices.
Implementation Method 1
The active noise control reduces noise by a speaker outputting control sound that has the same amplitude and the reverse phase relative to the noise
Implementation Method 2
a plurality of microphones 17 arranged around the rotor 11 convert the control sound and noise into microphone signals
Data Source
AI summary
According to one embodiment, a noise reduction device includes speakers, microphones, and a processing circuit. The speakers are arranged around a rotor and emit control sound based on control signals. The microphones are arranged around the rotor and convert the control sound and noise emitted by the rotor into microphone signals. The processing circuit generates the control signals for reducing acoustic power in positions of the microphones, based on the microphone signals, rotation speed of the rotor, and a phase of noise that reaches the microphones from the rotor.