Effect of sudden change in free stream velocity on the wind turbine airfoil performance based on boundary element method

2019 ◽  
Vol 101 ◽  
pp. 360-370
Author(s):  
Saeed Karimian Aliabadi ◽  
Sepehr Rasekh
Keyword(s):  
Boundary Element Method ◽  
Wind Turbine ◽  
Boundary Element ◽  
Free Stream ◽  
Sudden Change ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Wind Turbine Airfoil ◽  
Element Method

Experimental Study on Performance of Vertical Axis Wind Turbine with NACA 4-Digital Series of Blades

2012 ◽  
Vol 488-489 ◽  
pp. 1055-1061 ◽  
Author(s):  
W.C. Hsieh ◽  
J.M. Miao ◽  
C.C. Lai ◽  
C.S. Tai
Keyword(s):  
Wind Turbine ◽  
Output Power ◽  
Free Stream ◽  
Rotation Speed ◽  
Vertical Axis ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
Test Model ◽  
Vertical Axis Wind Turbine ◽  
Blade Section

The experimental studies of output power performances of a vertical-axis-wind-turbine (VAWT) had been conducted in suction-type low speed wind tunnel with various free stream velocity. Torque and rotation speed of blades were measured by using torque meter and optical detector to analyze the effect of blade-section shape on the performance of wind turbine. The test model of experiments in the research was H-rotor VAWT. Three shapes of the NACA 4-digital series blade-section, NACA0022, NACA6404, and NACA6422 were taken in this work. Effects of thickness and camber of blade-section, blade numbers, and blade setting angles on the performance of VAWT have been analyzed in detail. The results show that NACA6422 blade-section has rotation speed of 42% higher than that of NACA0022 when the free stream velocity is below 12 m/s and the blade numbers are 4-blade type. Wind turbines with NACA6422 blades also showed that about 10% higher output power than that of NACA0022 blades among the tested range of free stream velocity. Results indicated that wind turbine with blades of anti-symmetric and thick blade-section was generally more suitable for applying to VAWT. All results of this study can be used the optimization design of VAWT blades in further.

scholarly journals Development of a Computational System to Improve Wind Farm Layout, Part I: Model Validation and Near Wake Analysis

Energies ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 940 ◽  
Author(s):  
Rafael Rodrigues ◽  
Corinne Lengsfeld
Keyword(s):  
Wind Turbine ◽  
Pitch Angle ◽  
Wind Farm ◽  
Free Stream ◽  
Free Stream Velocity ◽  
Speed Ratio ◽  
Stream Velocity ◽  
Near Wake ◽  
Tip Speed Ratio ◽  
Wind Farm Layout

The first part of this work describes the validation of a wind turbine farm Computational Fluid Dynamics (CFD) simulation using literature velocity wake data from the MEXICO (Model Experiments in Controlled Conditions) experiment. The work is intended to establish a computational framework from which to investigate wind farm layout, seeking to validate the simulation and identify parameters influencing the wake. A CFD model was designed to mimic the MEXICO rotor experimental conditions and simulate new operating conditions with regards to tip speed ratio and pitch angle. The validation showed that the computational results qualitatively agree with the experimental data. Considering the designed tip speed ratio (TSR) of 6.6, the deficit of velocity in the wake remains at rate of approximately 15% of the free-stream velocity per rotor diameter regardless of the free-stream velocity applied. Moreover, analysis of a radial traverse right behind the rotor showed an increase of 20% in the velocity deficit as the TSR varied from TSR = 6 to TSR = 10, corresponding to an increase ratio of approximately 5% m·s−1 per dimensionless unit of TSR. We conclude that the near wake characteristics of a wind turbine are strongly influenced by the TSR and the pitch angle.

scholarly journals Far-wake meandering induced by atmospheric eddies in flow past a wind turbine

2018 ◽  
Vol 846 ◽  
pp. 190-209 ◽  
Author(s):  
X. Mao ◽  
J. N. Sørensen
Keyword(s):  
Wind Turbine ◽  
Strouhal Number ◽  
Large Scale ◽  
Free Stream ◽  
Stokes Equations ◽  
Wind Farms ◽  
Free Stream Velocity ◽  
Immersed Boundary ◽  
Stream Velocity ◽  
Actuator Disc

A novel algorithm is developed to calculate the nonlinear optimal boundary perturbations in three-dimensional incompressible flow. An optimal step length in the optimization loop is calculated without any additional calls to the Navier–Stokes equations. The algorithm is applied to compute the optimal inflow eddies for the flow around a wind turbine to clarify the mechanisms behind wake meandering, a phenomenon usually observed in wind farms. The turbine is modelled as an actuator disc using an immersed boundary method with the loading prescribed as a body force. At Reynolds number (based on free-stream velocity and turbine radius) $Re=1000$, the most energetic inflow perturbation has a frequency $\unicode[STIX]{x1D714}=0.8$–2, and is in the form of an azimuthal wave with wavenumber $m=1$ and the same radius as the actuator disc. The inflow perturbation is amplified by the strong shear downstream of the edge of the disc and then tilts the rolling-up vortex rings to induce wake meandering. This mechanism is verified by studying randomly perturbed flow at $Re\leqslant 8000$. At five turbine diameters downstream of the disc, the axial velocity oscillates at a magnitude of more than 60 % of the free-stream velocity when the magnitude of the inflow perturbation is 6 % of the free-stream wind speed. The dominant Strouhal number of the wake oscillation is 0.16 at $Re=3000$ and keeps approximately constant at higher $Re$. This Strouhal number agrees well with previous experimental findings. Overall the observations indicate that the well-observed stochastic wake meandering phenomenon appearing far downstream of wind turbines is induced by large-scale (the same order as the turbine rotor) and low-frequency free-stream eddies.

A BOUNDARY-ELEMENT METHOD FOR ATOMIZATION OF A FINITE LIQUID JET

1995 ◽  
Vol 5 (6) ◽  
pp. 621-638 ◽  
Author(s):  
J. H. Hilbing ◽  
Stephen D. Heister ◽  
C. A. Spangler
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Liquid Jet ◽  
Element Method

Application of the Boundary Element Method and Modal Analysis to Tire Acoustics Problems

1993 ◽  
Vol 21 (2) ◽  
pp. 66-90 ◽  
Author(s):  
Y. Nakajima ◽  
Y. Inoue ◽  
H. Ogawa
Keyword(s):  
Finite Element ◽  
Boundary Element Method ◽  
Boundary Element ◽  
Acoustic Radiation ◽  
Traffic Noise ◽  
Noise Prediction ◽  
Prediction System ◽  
Tire Noise ◽  
Acoustic Contribution ◽  
Element Method

Abstract Road traffic noise needs to be reduced, because traffic volume is increasing every year. The noise generated from a tire is becoming one of the dominant sources in the total traffic noise because the engine noise is constantly being reduced by the vehicle manufacturers. Although the acoustic intensity measurement technology has been enhanced by the recent developments in digital measurement techniques, repetitive measurements are necessary to find effective ways for noise control. Hence, a simulation method to predict generated noise is required to replace the time-consuming experiments. The boundary element method (BEM) is applied to predict the acoustic radiation caused by the vibration of a tire sidewall and a tire noise prediction system is developed. The BEM requires the geometry and the modal characteristics of a tire which are provided by an experiment or the finite element method (FEM). Since the finite element procedure is applied to the prediction of modal characteristics in a tire noise prediction system, the acoustic pressure can be predicted without any measurements. Furthermore, the acoustic contribution analysis obtained from the post-processing of the predicted results is very helpful to know where and how the design change affects the acoustic radiation. The predictability of this system is verified by measurements and the acoustic contribution analysis is applied to tire noise control.

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