scholarly journals A comparison between aeroacoustic source mapping techniques for the characterisation of wind turbine blade models with microphone arrays

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 147
Author(s):  
Gianmarco Battista ◽  
Marcello Vanali ◽  
Paolo Chiariotti ◽  
Paolo Castellini
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Microphone Array ◽  
Wind Turbine Blade ◽  
Operating Conditions ◽  
Noise Sources ◽  
Aeroacoustic Noise ◽  
Array Measurements ◽  
Mapping Techniques ◽  
Acoustic Mapping

<p class="Abstract">Characterising the aeroacoustic noise sources generated by a rotating wind turbine blade provides useful information for tackling noise reduction of this mechanical system. In this context, microphone array measurements and acoustic source mapping techniques are powerful tools for the identification of aeroacoustic noise sources. This paper discusses a series of acoustic mapping strategies that can be exploited in this kind of applications. A single-blade rotor was tested in a semi-anechoic chamber using a circular microphone array. <br />The Virtual Rotating Array (VRA) approach, which transforms the signals acquired by the physical static array into signals of virtual microphones synchronously rotating with the blade, hence ensuring noise-source stationarity, was used to enable the use of frequency domain acoustic mapping techniques. A comparison among three different acoustic mapping methods is presented: Conventional Beamforming, CLEAN-SC and Covariance Matrix Fitting based on Iterative Re-weighted Least Squares and Bayesian approach. The latter demonstrated to provide the best results for the application and made it possible a detailed characterization of the noise sources generated by the rotating blade at different operating conditions.</p>

Study on Unified Chaotic System-Based Wind Turbine Blade Fault Diagnostic System

2015 ◽  
Vol 25 (03) ◽  
pp. 1550042 ◽  
Author(s):  
Ying-Che Kuo ◽  
Chin-Tsung Hsieh ◽  
Her-Terng Yau ◽  
Yu-Chung Li
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Chaotic System ◽  
Wind Turbines ◽  
Diagnostic System ◽  
Vibration Signal ◽  
Wind Turbine Blade ◽  
Operating Conditions ◽  
Unified Chaotic System ◽  
Fault Diagnostic

At present, vibration signals are processed and analyzed mostly in the frequency domain. The spectrum clearly shows the signal structure and the specific characteristic frequency band is analyzed, but the number of calculations required is huge, resulting in delays. Therefore, this study uses the characteristics of a nonlinear system to load the complete vibration signal to the unified chaotic system, applying the dynamic error to analyze the wind turbine vibration signal, and adopting extenics theory for artificial intelligent fault diagnosis of the analysis signal. Hence, a fault diagnostor has been developed for wind turbine rotating blades. This study simulates three wind turbine blade states, namely stress rupture, screw loosening and blade loss, and validates the methods. The experimental results prove that the unified chaotic system used in this paper has a significant effect on vibration signal analysis. Thus, the operating conditions of wind turbines can be quickly known from this fault diagnostic system, and the maintenance schedule can be arranged before the faults worsen, making the management and implementation of wind turbines smoother, so as to reduce many unnecessary costs.

scholarly journals Investigation of Laminar-Turbulent Transition on a Rotating Wind Turbine Blade of Multi Megawatt Class with Thermography and a Microphone Array

2019 ◽  
Author(s):  
Torben Reichstein ◽  
Alois Peter Schaffarczyk ◽  
Christoph Dollinger ◽  
Nicolas Balaresque ◽  
Erich Schuelein ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Microphone Array ◽  
Turbine Blades ◽  
Suction Side ◽  
Wind Turbine Blade ◽  
Flow Transition ◽  
Turbulent Transition ◽  
Laminar Turbulent Transition

Knowledge about laminar-turbulent transition on operating multi-megawatt wind turbine blades needs sophisticated equipment like hot-films or microphone arrays. Contrarily thermographic pictures can easily be taken from the ground and temperature differences indicate different states of the boundary layer. The accuracy however, still is an open question, so that an aerodynamic glove known from experimental research on aero-planes was used to classify the boundary-layer state of a 2 megawatt wind turbine blade operating in the orthern part of Schleswig-Holstein, Germany. State-of-the-art equipment for measurering static surface pressure was used for monitoring the lift distribution. To distinguish laminar and turbulent parts of the boundary layer (suction side only) 48 microphones were applied together with ground-based thermographic cameras from two teams. Additionally, an optical camera mounted on the hub was used to survey vibrations. During start-up (from 0 to 9 rpm) extended, but irregularly shaped regions of a laminar boundary layer were observed which had the same extension measured both with microphones and Thermography. When an approximately constant rotor rotation (9 rpm corresponding to approximately 6 m/s wind-speed) was achieved, a flow transition was visible at the expected position of 40 % chord length on the rotor blade, which was fouled with dense turbulent wedges and an almost complete turbulent state on the glove was detected. In all observations, quantitative determination of the flow transition positions from thermography and microphones agree well within their accuracy.

Analysis of long wind turbine blades with shape memory alloy wires in super-elastic phase

2018 ◽  
Vol 29 (15) ◽  
pp. 3108-3123 ◽  
Author(s):  
Rodrigo Nicoletti ◽  
Robert Liebich
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Profile ◽  
Turbine Blades ◽  
Wind Turbine Blade ◽  
Operating Conditions ◽  
Hysteretic Behavior ◽  
Alloy Material

In this work, shape memory alloy wires are modeled and included in the model of a wind turbine blade, in order to numerically study their effect on blade vibrations under operating conditions. The blade is modeled using finite elements considering flapwise, edgewise, and torsional motion subjected to the effects of rotation and to a normal wind profile. The shape memory alloy wires are modeled in the super-elastic phase, thus presenting a hysteresis loop as a function of strain and ambient temperature. Such a hysteretic behavior of the shape memory alloy material adds damping to the structure that it is attached to. The numerical results show that inserting shape memory alloy wires in the wind turbine blade presents drawbacks, because the excitation level of the normal wind profile is not big enough for the blade to present significant strain. Hence, the hysteresis loops in the shape memory alloy material mounted on the blade have small areas which, consequently, reduce the amount of damping added to the blade. Besides, the added damping is restricted to the upper 30% of the blade (area of higher strain in the blade).

Noise analysis of the wind turbine blade

2013 ◽  
Author(s):  
Gwochung Tsai ◽  
Yita Wang ◽  
Yuhchung Hu ◽  
Jaching Jiang
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Noise Analysis ◽  
Wind Turbine Blade

DYNAMIC ANALYSIS OF THE FLUID FLOW OVER A WIND TURBINE BLADE

2017 ◽  
Author(s):  
Aldemir Ap Cavalini Jr ◽  
João Marcelo Vedovoto ◽  
Renata Rocha
Keyword(s):  
Fluid Flow ◽  
Dynamic Analysis ◽  
Wind Turbine ◽  
Turbine Blade ◽  
Wind Turbine Blade

scholarly journals Aeroacoustic noise reduction by application of end plates on wall-mounted finite airfoils

2021 ◽  
Vol 62 (5) ◽  
Author(s):  
Erik Schneehagen ◽  
Thomas F. Geyer ◽  
Ennes Sarradj ◽  
Danielle J. Moreau
Keyword(s):  
Noise Reduction ◽  
Microphone Array ◽  
Boundary Layer Transition ◽  
Tip Vortex ◽  
Layer Transition ◽  
Aeroacoustic Noise ◽  
End Plate ◽  
Array Measurements ◽  
Field Noise ◽  
Naca 0012

Abstract One known method to reduce vortex shedding from the tip of a blade is the use of end plates or winglets. Although the aerodynamic impact of such end plates has been investigated in the past, no studies exist on the effect of such end plates on the far-field noise. The aeroacoustic noise reduction of three different end-plate geometries is experimentally investigated. The end plates are applied to the free end of a wall-mounted symmetric NACA 0012 airfoil and a cambered NACA 4412 airfoil with an aspect ratio of 2 and natural boundary layer transition. Microphone array measurements are taken in the aeroacoustic open-jet wind tunnel at BTU Cottbus-Senftenberg for chord-based Reynolds numbers between 75,000 and 225,000 and angles of attack from 0$$^\circ$$ ∘ to 30$$^\circ$$ ∘ . The obtained acoustic spectra show a broad frequency hump for the airfoil base configurations at higher angles of attack that is attributed to tip noise. Hot-wire measurements taken for one configuration show that the application of an end plate diffuses the vorticity at the tip. The aeroacoustic noise contribution of the tip can be reduced when the endplates are applied. This reduction is most effective for higher angles of attack, when the tip vortex is the dominant sound source. Graphic abstract

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