Modeling of Aerodynamically Generated Noise From Wind Turbines

2005 ◽  
Vol 127 (4) ◽  
pp. 517-528 ◽  
Author(s):  
Wei Jun Zhu ◽  
Nicolai Heilskov ◽  
Wen Zhong Shen ◽  
Jens Nørkær Sørensen
Keyword(s):  
Boundary Layer ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Aerodynamic Noise ◽  
Generation Model ◽  
Two Dimensional ◽  
Noise Emission ◽  
Total Noise ◽  
Element Input ◽  
Blade Element

A semiempirical acoustic generation model based on the work of Brooks, Pope, and Marcolini [NASA Reference Publication 1218 (1989)] has been developed to predict aerodynamic noise from wind turbines. The model consists of dividing the blades of the wind turbine into two-dimensional airfoil sections and predicting the total noise emission as the sum of the contribution from each blade element. Input is the local relative velocities and boundary layer parameters. These quantities are obtained by combining the model with a Blade Element Momentum (BEM) technique to predict local inflow characteristics to the blades. Boundary layer characteristics are determined from two-dimensional computations of airfoils. The model is applied to the Bonus 300 kW wind turbine at a wind speed of 8 m/s. Comparisons of total noise spectra show good agreement with experimental data.

scholarly journals Modeling and simulation of forces applied to the horizontal axis wind turbine rotors by the vortex method coupled with the method of the blade element

2021 ◽  
Vol 12 (1) ◽  
pp. 413
Author(s):  
Ibtissem Barkat ◽  
Abdelouahab Benretem ◽  
Fawaz Massouh ◽  
Issam Meghlaoui ◽  
Ahlem Chebel
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Wind Farms ◽  
Vortex Method ◽  
Operating Conditions ◽  
Horizontal Axis ◽  
Rotor Blades ◽  
Good Representation ◽  
Horizontal Axis Wind Turbine ◽  
Blade Element

This article aims to study the forces applied to the rotors of horizontal axis wind turbines. The aerodynamics of a turbine are controlled by the flow around the rotor, or estimate of air charges on the rotor blades under various operating conditions and their relation to the structural dynamics of the rotor are critical for design. One of the major challenges in wind turbine aerodynamics is to predict the forces on the blade as various methods, including blade element moment theory (BEM), the approach that is naturally adapted to the simulation of the aerodynamics of wind turbines and the dynamic and models (CFD) that describes with fidelity the flow around the rotor. In our article we proposed a modeling method and a simulation of the forces applied to the horizontal axis wind rotors turbines using the application of the blade elements method to model the rotor and the vortex method of free wake modeling in order to develop a rotor model, which can be used to study wind farms. This model is intended to speed up the calculation, guaranteeing a good representation of the aerodynamic loads exerted by the wind.

Effect of Flow Inclination on Wind Turbine Performance

2012 ◽  
Vol 134 (12) ◽  
Author(s):  
Christina Tsalicoglou ◽  
Sarah Barber ◽  
Ndaona Chokani ◽  
Reza S. Abhari
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Complex Terrain ◽  
Wake Flow ◽  
Test Facility ◽  
Power Coefficient ◽  
Incoming Flow ◽  
Turbine Performance ◽  
The Impact ◽  
Blade Element

This work examines the effect of flow inclination on the performance of a stand-alone wind turbine and of wind turbines operating in the wakes of upstream turbines. The experimental portion of this work, which includes performance and flowfield measurements, is conducted in the ETH dynamically-scaled wind turbine test facility, with a wind turbine model that can be inclined relative to the incoming flow. The performance of the wind turbine is measured with an in-line torquemeter, and a 5-hole steady-state probe is used to detail the inflow and wake flow of the turbine. Measurements show that over a range of tip-speed ratios of 4–7.5, the power coefficient of a wind turbine with an incoming flow of 15 deg inclination decreases on average by 7% relative to the power coefficient of a wind turbine with a noninclined incoming flow. Flowfield measurements show that the wake of a turbine with an inclined incoming flow is deflected; the deflection angle is approximately 6 deg for an incoming flow with 15 deg inclination. The measured wake profiles are used as inflow profiles for a blade element momentum code in order to quantify the impact of flow inclination on the performance of downstream wind turbines. In comparison to the case without inclination in the incoming flow, the combined power output of two aligned turbines with incoming inclined flow decreases by 1%, showing that flow inclination in complex terrain does not significantly reduce the energy production.

Prediction of Aerodynamic Noise Radiated From a Vertical-Axis Wind Turbine

2003 ◽  
Author(s):  
Akiyoshi Iida ◽  
Akisato Mizuno ◽  
Kyoji Kamemoto
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Sound Source ◽  
Vertical Axis ◽  
Aerodynamic Performance ◽  
Low Noise ◽  
Aerodynamic Noise ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbine

Unsteady flow field and flow induced noise of vertical axis wind turbine are numerically investigated. The flow field is numerically calculated by the vortex method with core-spreading model. This simulation obtains aerodynamic performance and aerodynamic forces. Aerodynamic noise is also simulated by using Ffowcs Williams-Hawkings equation with compact body and low-Mach number assumptions. Tip speed of rotor blades are not so high, then the contribution of the moving sound source is smaller than that of the dipole sound source. Since the maximum power coefficient of VAWT can be obtained at lower tip-speed ratio compared to the conventional, horizontal axis wind turbines, the aerodynamic noise from vertical axis wind turbine is smaller than that of the conventional wind turbines at the same aerodynamic performance. This result indicates that the vertical axis wind turbines are useful to develop low-noise wind turbines.

scholarly journals Development of an Efficient Numerical Method for Wind Turbine Flow, Sound Generation, and Propagation under Multi-Wake Conditions

2018 ◽  
Vol 9 (1) ◽  
pp. 100 ◽  
Author(s):  
Zhenye Sun ◽  
Wei Zhu ◽  
Wen Shen ◽  
Emre Barlas ◽  
Jens Sørensen ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Numerical Method ◽  
Wind Turbines ◽  
Noise Source ◽  
Axisymmetric Flow ◽  
Wake Flow ◽  
Propagation Path ◽  
Aerodynamic Noise ◽  
Long Distance ◽  
Noise Propagation

The propagation of aerodynamic noise from multi-wind turbines is studied. An efficient hybrid method is developed to jointly predict the aerodynamic and aeroacoustics performances of wind turbines, such as blade loading, rotor power, rotor aerodynamic noise sources, and propagation of noise. This numerical method combined the simulations of wind turbine flow, noise source and its propagation which is solved for long propagation path and under complex flow environment. The results from computational fluid dynamics (CFD) calculations not only provide wind turbine power and thrust information, but also provide detailed wake flow. The wake flow is computed with a 2D actuator disc (AD) method that is based on the axisymmetric flow assumption. The relative inflow velocity and angle of attack (AOA) of each blade element form input data to the noise source model. The noise source is also the initial condition for the wave equation that solves long distance noise propagation in frequency domain. Simulations were conducted under different atmospheric conditions which showed that wake flow is an important part that has to be included in wind turbine noise propagation.

Experimental Investigation on the Wake Characteristics and Aeromechanics of Dual-Rotor Wind Turbines

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Ahmet Ozbay ◽  
Wei Tian ◽  
Hui Hu
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Flow Characteristics ◽  
Wake Flow ◽  
Neutral Stability ◽  
Flow Measurements ◽  
Wake Characteristics

An experimental study was carried out to investigate the aeromechanics and wake characteristics of dual-rotor wind turbines (DRWTs) in either co-rotating or counter-rotating configuration, in comparison to those of a conventional single-rotor wind turbine (SRWT). The experiments were performed in a large-scale aerodynamic/atmospheric boundary layer (AABL) wind tunnel, available at Iowa State University with the oncoming atmospheric boundary-layer (ABL) airflows under neutral stability conditions. In addition to measuring the power output performance of DRWT and SRWT models, static and dynamic wind loads acting on those turbine models were also investigated. Furthermore, a high-resolution digital particle image velocimetry (PIV) system was used to quantify the flow characteristics in the near wakes of the DRWT and SRWT models. The detailed wake-flow measurements were correlated with the power outputs and wind-load measurement results of the wind-turbine models to elucidate the underlying physics to explore/optimize design of wind turbines for higher power yield and better durability.

Physical Model Study of the Wind Turbine Array Boundary Layer

2014 ◽  
Author(s):  
Kyle Charmanski ◽  
John Turner ◽  
Martin Wosnik
Keyword(s):  
Boundary Layer ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Hot Wire ◽  
Flow Measurements ◽  
Model Study ◽  
Power Rate ◽  
First Results ◽  
Upstream Part ◽  
Measurement Location

First results from an experimental investigation of the fully developed wind turbine array boundary layer are reported, using arrays of up to 100 model wind turbines with a diameter of 0.25 m. The wind turbine array was simulated by a combination of drag-matched porous disks, used in the upstream part of the array, and by a smaller array of realistically scaled 3-bladed wind turbines just upstream of the measurement location. The model array was placed in the 6.0 m × 2.7 m × 72.0 m test section of the UNH Flow Physics Facility. Power, rate of rotation and rotor thrust were measured for select turbines, and hot-wire anemometry was used for flow measurements. Development of a fully developed wind turbine array boundary layer was noted with increase in array size.

scholarly journals Impacts of the low-level jet's negative wind shear on the wind turbine

2017 ◽  
Vol 2 (2) ◽  
pp. 533-545 ◽  
Author(s):  
Walter Gutierrez ◽  
Arquimedes Ruiz-Columbie ◽  
Murat Tutkun ◽  
Luciano Castillo
Keyword(s):  
Boundary Layer ◽  
Wind Speed ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Real Life ◽  
Horizontal Wind ◽  
Major Power ◽  
Low Level ◽  
Wind Speed Maximum ◽  
Wind Shears

Abstract. Nocturnal low-level jets (LLJs) are defined as relative maxima in the vertical profile of the horizontal wind speed at the top of the stable boundary layer. Such peaks constitute major power resources for wind turbines. However, a wind speed maximum implies a transition from positive wind shears below the peak to negative ones above. The effect that such a transition has on wind turbines has not been thoroughly studied.This research study employed a methodical approach to the study of negative wind shear's impacts on wind turbines. Up to now, the presence of negative shears inside the turbine's rotor in relation to the presence of positive shears has been largely ignored. A parameter has been proposed to quantify that presence in future studies of LLJ–wind-turbine interactions. Simulations were performed using the NREL aeroelastic simulator FAST code. Rather than using synthetic profiles to generate the wind data, all simulations were based on real data captured at the high frequency of 50 Hz, which allowed us to perform the analysis of a turbine's impacts with real-life, small scales of wind motions.It was found that the presence of negative wind shears at the height of the turbine's rotor appeared to exert a positive impact on reducing the motions of the nacelle and the tower in every direction, with oscillations reaching a minimum when negative shears covered the turbine swept area completely. Only the tower wobbling in the spanwise direction was amplified by the negative shears; however, this occurred at the tower's slower velocities and accelerations. The forces and moments were also reduced by the negative shears. The aforementioned impacts were less beneficial in the rotating parts, such as the blades and the shafts. Finally, the variance in power production was also reduced. These findings can be very important for the next generation of wind turbines as they reach deeper into LLJ's typical heights.The study demonstrated that the presence of negative shears is significant in reducing the loading on wind turbines. A major conclusion of this study is that the wind turbines of the future should probably be designed with the aim of reaching the top of the nightly boundary layer more often and therefore the altitudes where negative shears are more frequent. Doing so will help to reduce the positive shear's associated damage and to capture the significant LLJ energy.

Assessment of a Modified Blade Element Momentum Methodology for Diffuser Augmented Wind Turbines

2017 ◽  
Author(s):  
Stavros N. Leloudas ◽  
Georgios N. Lygidakis ◽  
Ioannis K. Nikolos
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Power Output ◽  
Horizontal Axis Wind Turbine ◽  
Correction Model ◽  
Short Period ◽  
Turbine Design ◽  
The Impact ◽  
Bem Theory ◽  
Blade Element

The Blade Element Momentum (BEM) theory is nowadays the cornerstone of the horizontal axis wind turbine design, as its application allows for the accurate aerodynamic simulation and power output prediction of wind turbine rotors in a remarkably short period of time. Therefore, efforts have been made for the extension of the classic BEM theory to the performance analysis of Diffuser Augmented Wind Turbines (DAWTs) as well. In this study, the development and assessment of such an in-house BEM code are presented. The proposed computational model is based on the modification of the momentum part of the classical BEM theory; thus, it is capable to account for the diffuser’s effect on the calculation of the axial and tangential induction factors, through the utilization of the velocity speed-up distribution over the rotor plane of the unloaded diffuser. Furthermore, a detailed Glauert’s correction model, which employs Buhl’s modification, specially tailored for the DAWT case is included, to deal with the high values of the axial induction factor. The accuracy of the model is assessed against numerical and experimental results available in the literature, while the impact of the Prandtl’s tip loss correction model on the rotor’s predicted power output is also examined.

An Experimental Investigation on the Wake Characteristics and Aeromechanics of Dual-Rotor Wind Turbines

2015 ◽  
Author(s):  
Ahmet Ozbay ◽  
Wei Tian ◽  
Hui Hu
Keyword(s):  
Boundary Layer ◽  
Atmospheric Boundary Layer ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Flow Characteristics ◽  
Wake Flow ◽  
Neutral Stability ◽  
Flow Measurements ◽  
Wake Characteristics

An experimental study was carried out to investigate the aeromechanics and wake characteristics of dual-rotor wind turbines (DRWTs ) in either co-rotating or counter-rotating configuration, in comparison to those of a conventional single-rotor wind turbine (SRWT). The experiments were performed in a large-scale Aerodynamic/Atmospheric Boundary Layer (AABL) wind tunnel available at Iowa State University with the oncoming Atmospheric Boundary Layer (ABL) airflows under neutral stability conditions. In addition to measuring the power output performance of DRWT and SRWT models, static and dynamic wind loads acting on those turbine models were also investigated. Furthermore, a high resolution digital particle image velocimetry (PIV) system was used to quantify the flow characteristics in the near wakes of the DRWT and SRWT models. The detailed wake flow measurements were correlated with the power outputs and wind load measurement results of the wind turbine models to elucidate the underlying physics to explore/optimize design of wind turbines for higher power yield and better durability.

scholarly journals Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5564
Author(s):  
Rosario Lanzafame ◽  
Stefano Mauro ◽  
Michele Messina ◽  
Sebastian Brusca
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Time Step ◽  
Vertical Axis Wind Turbines ◽  
2D Model

The simulation of very small vertical axis wind turbines is often a complex task due to the very low Reynolds number effects and the strong unsteadiness related to the rotor operation. Moreover, the high boundary layer instabilities, which affect these turbines, strongly limits their efficiency compared to micro horizontal axis wind turbines. However, as the scientific interest toward micro wind turbine power generation is growing for powering small stand-alone devices, Vertical Axis Wind Turbines (VAWTs)might be very suitable for this kind of application as well. Furthermore, micro wind turbines are widely used for wind tunnel testing, as the wind tunnel dimensions are usually quite limited. In order to obtain a better comprehension of the fluid dynamics of such micro rotors, in the present paper the authors demonstrate how to develop an accurate CFD 2D model of a micro H-Darrieus wind turbine, inherently characterized by highly unstable operating conditions. The rotor was tested in the subsonic wind tunnel, owned by the University of Catania, in order to obtain the experimental validation of the numerical model. The modeling methodology was developed by means of an accurate grid and time step sensitivity study and by comparing different approaches for the turbulence closure. The hybrid LES/RANS Delayed Detached Eddy Simulation, coupled to a transition model, demonstrated superior accuracy compared to the most advanced unsteady RANS models. Therefore, the CFD 2D model developed in this work allowed for a thorough insight into the unstable fluid dynamic operating conditions of micro VAWTs, leading the way for the performance improvement of such rotors.

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