Rotor Blade Active Noise Control via Anti-Phase Signals
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Solution Overview
Problem
Flow-induced edge noise in rotor blades, particularly in wind turbines, remains a significant issue despite existing noise reduction methods, necessitating further solutions to comply with noise regulations and minimize operational curtailment.
Innovation Solution
Integration of sensors and actuators on the rotor blade surface, connected by a flexible tube, to detect fluid flow characteristics and produce anti-noise signals that cancel out noise generated at the trailing edge, leveraging the 'frozen turbulence' assumption to effectively reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional noise reduction methods (such as serrations) are applied to the rotor blade, then some noise reduction is achieved, but the flow-induced edge noise remains considerable and further reduction is difficult
Solution Approach 1:
The patent applies preliminary anti-action by generating anti-noise signals that are phase-opposite to the predicted turbulent eddies before they reach the trailing edge. The sensor detects flow characteristics upstream, the controller predicts eddy arrival, and the actuator produces canceling signals in advance, creating destructive interference with the incoming noise waves and achieving significant noise reduction beyond conventional methods
Solution Approach 2:
The patent replaces passive mechanical noise reduction structures (such as fixed serrations) with an active control system that uses sensors, controllers, and actuators to dynamically generate anti-noise signals. This substitution allows for adaptive noise cancellation that responds to real-time flow conditions, achieving superior noise reduction performance
2Object-affected harmful factors
If wind turbines are placed further away from residential areas to comply with noise regulations, then noise impact is reduced, but energy production and productivity decrease
Solution Approach 1:
By implementing active noise control that generates anti-noise signals in advance of turbulent eddy arrival, the system achieves significant noise reduction at the source. This allows wind turbines to be operated closer to residential areas while maintaining compliance with noise regulations, thereby preserving energy production productivity without requiring increased distances
3Object-affected harmful factors
If wind turbines are curtailed to maintain maximum allowed noise levels, then noise regulations are complied with, but operational time and energy production are reduced
Solution Approach 1:
The active noise control system continuously generates anti-noise signals to cancel flow-induced edge noise in real-time, enabling wind turbines to operate at full capacity without exceeding noise regulations. This eliminates the need for curtailment operations, maximizing operational duration and energy production while maintaining compliance with noise level restrictions
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
Significantly reduces or eliminates flow-induced edge noise by generating anti-noise signals in anti-phase with turbulent eddies, improving compliance with noise regulations and reducing operational limitations.
Implementation Method 1
the membranes arranged and prepared such that flow-induced edge noise of the rotor blade, which is generated by the fluid at the trailing edge of the rotor blade, is at least partly cancelled out
Implementation Method 2
one on the pressure side and one on the suction side of the airfoil, and connected by a flexible tube each membrane acting as a sensor for detecting flow characteristics of the fluid and as an actuator for producing an anti-noise signal
Implementation Method 3
connected by a flexible tube each membrane acting as a sensor for detecting flow characteristics of the fluid and as an actuator for producing an anti-noise signal
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a rotor blade (20) with a leading edge (23) and a trailing edge (24), wherein the rotor blade (20) is designed and configured for being exposed to a fluid flowing substantially from the leading edge (23) to the trailing edge (24) of the rotor blade (20), the rotor blade (20) comprises at least one sensor (31) for detecting flow characteristics of the fluid, and the rotor blade (20) further comprises at least one actuator (32) for producing an anti-noise signal. The sensor (31) and the actuator (32) are both arranged at the surface of the rotor blade (20), and the actuator (32) is arranged and prepared such that flow-induced edge noise of the rotor blade (20), which is generated by the fluid, is at least partly cancelled out by the anti-noise signal. The invention furthermore relates to a wind turbine comprising at least one such rotor blade (20).