Bubble-Induced Unsteadiness on A Wind Turbine Airfoil

2002 ◽  
Vol 124 (4) ◽  
pp. 335-344 ◽  
Author(s):  
E. A. Mayda ◽  
C. P. van Dam
Keyword(s):  
Wind Turbine ◽  
Aerodynamic Force ◽  
Horizontal Axis ◽  
Horizontal Axis Wind Turbine ◽  
Airfoil Surface ◽  
Laminar Separation ◽  
Surface Pressure Distribution ◽  
Horizontal Axis Wind Turbines ◽  
Wind Turbine Airfoil ◽  
Force Characteristics

The effect of laminar separation bubbles on the surface pressure distribution and aerodynamic force characteristics of a horizontal axis wind turbine airfoil is studied numerically. The NREL S809 airfoil for stall-controlled horizontal-axis wind turbines is analyzed at a chord Reynolds number of 1.0×106. For all flow conditions involving laminar separation in the present study, bubble-induced vortex shedding is observed. This flow phenomenon causes significant oscillations in the airfoil surface pressures and, hence, in the airfoil-generated aerodynamic forces. The computed time-averaged pressures compare favorably with wind-tunnel measurements.

Bubble Induced Unsteadiness on Wind Turbine Airfoils

2002 ◽  
Author(s):  
E. A. Mayda ◽  
C. P. van Dam ◽  
Earl P. N. Duque
Keyword(s):  
Reynolds Number ◽  
Vortex Shedding ◽  
Aerodynamic Force ◽  
Airfoil Surface ◽  
Laminar Separation ◽  
Flow Phenomenon ◽  
Surface Pressure Distribution ◽  
Horizontal Axis Wind Turbines ◽  
Turbine Airfoils ◽  
Force Characteristics

The effect of laminar separation bubbles on the surface pressure distribution and aerodynamic force characteristics of two quite different airfoils is studied numerically. The low-Reynolds-number Eppler E387 airfoil is analyzed at a chord Reynolds number of 1.0×105 whereas the NREL S809 airfoil for horizontal-axis wind turbines is analyzed at 1.0×106. For all cases in the present study, bubble induced vortex shedding is observed. This flow phenomenon causes significant oscillations in the airfoil surface pressures and, hence, airfoil generated aerodynamic forces. The computed time-averaged pressures compare favorably with wind-tunnel measurements for both airfoils.

scholarly journals Study and Design of a Horizontal Axis Wind Turbine (0.5 kW) Using Software Solid Works

2021 ◽  
pp. 1-17
Author(s):  
Hagninou E. V. Donnou ◽  
Drissa Boro ◽  
Jean Noé Fabiyi ◽  
Marius Tovoeho ◽  
Aristide B. Akpo
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wedge Angle ◽  
Three Dimensional ◽  
Synchronous Generator ◽  
Horizontal Axis ◽  
Geometrical Shape ◽  
Horizontal Axis Wind Turbine ◽  
Horizontal Axis Wind Turbines ◽  
Lift And Drag

In the present work, the study and design of a horizontal axis wind turbine suitable for the Cotonou site were investigated on the coast of Benin. A statistical study using the Weibull distribution was carried out on the hourly wind data measured at 10 m from the ground by the Agency for Air Navigation Safety in Africa and Madagascar (ASECNA) over the period from January 1981 to December 2014. Then, the models, techniques, tools and approaches used to design horizontal axis wind turbines were presented and the wind turbine components characteristics were determined. The numerical design and assembly of these components were carried out using SolidWorks software. The results revealed that the designed wind turbine has a power of 571W. It is equipped with a permanent magnet synchronous generator and has three aluminum blades with NACA 4412 biconvex asymmetrical profile. The values obtained for the optimum coefficient of lift and drag are estimated at 1.196 and 0.0189 respectively. The blades are characterised by an attack optimum angle estimated at 6° and the wedge angle at 5°. Their length is 2.50 m and the maximum thickness is estimated at 0.032 m for a rope length of 0.27 m. The wind turbine efficiency is 44%. The computer program designed on SolidWorks gives three-dimensional views of the geometrical shape of the wind turbine components and their assembly has allowed to visualize the compact shape of the wind turbine after export via its graphical interface. The energy quantity that can be obtained from the wind turbine was estimated at 2712,718 kWh/year. This wind turbine design study is the first of its kind for the study area. In order to reduce the technological dependence and the import of wind energy systems, the results of this study could be used to produce lower cost wind energy available on our study site.

Visualization of the flow field and aerodynamic force on a Horizontal Axis Wind Turbine in turbulent inflows

Energy ◽  
2016 ◽  
Vol 111 ◽  
pp. 57-67 ◽  
Author(s):  
Qing'an Li ◽  
Yasunari Kamada ◽  
Takao Maeda ◽  
Junsuke Murata ◽  
Yusuke Nishida
Keyword(s):  
Flow Field ◽  
Wind Turbine ◽  
Aerodynamic Force ◽  
Horizontal Axis ◽  
Horizontal Axis Wind Turbine

Novel Curvature-Based Airfoil Parameterization for Wind Turbine Application and Optimization

2017 ◽  
Author(s):  
Karthik Balasubramanian ◽  
Mark G. Turner ◽  
Kiran Siddappaji
Keyword(s):  
Wind Turbine ◽  
Surface Pressure ◽  
Thickness Distribution ◽  
Department Of Energy ◽  
Second Derivative ◽  
Horizontal Axis Wind Turbine ◽  
Airfoil Surface ◽  
Tool Chain ◽  
Surface Pressure Distribution ◽  
Curvature Continuity

The direct proportionality of streamline curvature to the pressure gradient normal to it causes the dependence of surface pressure loading on geometry curvature. This allows for the use of geometry curvature as a direct and aerodynamically meaningful interface to modify and improve performance of wind turbine sections. A novel blade parameterization technique driven by specification of meanline second derivative and a thickness distribution is presented. This technique is implemented as T-Blade3 which is an already existing in-house open-executable. The second derivative which is indicative of curvature, is used, enabling exploration of a large design space with minimal number of parameters due to the use of B-spline control points, capable of producing smooth curves with only a few points. New thickness and curvature control capabilities have been added to TBlade3 for isolated and wind turbine airfoils. The parameterization ensures curvature and slope of curvature continuity on the airfoil surface which are critical to smooth surface pressure distribution. Consequently, losses due to unintentional pressure spikes are minimized and likelihood of separation reduced. As a demonstration of the parameterization capability, Multi-Objective optimization is carried out to maximize wind turbine efficiency. This is achieved through an optimization tool-chain that minimizes a weighted sum of the drag-to-lift ratios over a range of angles of attack and sectional Reynolds numbers using a Genetic Algorithm. This allows for radial Reynolds number variation and ensures efficiency of wind turbine blade with twist incorporated. The tool-chain uses XFOIL to evaluate drag polars. This is implemented in MATLAB and Python in serial and in parallel with the US Department of Energy optimization system, DAKOTA. The Python and DAKOTA versions of the code are fully open-source. The NREL S809 horizontal axis wind turbine laminar-flow airfoil which is 21% thick has been used as a benchmark for comparison. Hence, the optimization is carried out with the same thickness-to-chord ratio. Drag coefficient improvement ranging from 17% to 55% for Cl between 0.3 and 1 was achieved.

Horizontal Axis Wind Turbine Numerical Simulation of Two Dimensional Angle of Attack

2012 ◽  
Vol 619 ◽  
pp. 111-114
Author(s):  
Jing Mei Yu ◽  
Yan Hong Yu ◽  
Pan Pan Liu
Keyword(s):  
Numerical Simulation ◽  
Wind Turbine ◽  
Hot Spot ◽  
The United States ◽  
Aerodynamic Performance ◽  
Horizontal Axis ◽  
Energy Utilization ◽  
Two Dimensional ◽  
Horizontal Axis Wind Turbine ◽  
Wind Turbine Airfoil

wind power is the most effective form of wind energy utilization, modern large-scale wind turbine with horizontal axis wind mainly. Horizontal axis wind turbine aerodynamic performance calculation of the wind turbine aerodynamics research hot spot, is a wind turbine aerodynamic optimization design and calculation of critical load. Horizontal axis wind turbine airfoil aerodynamic performance of the wind turbine operation characteristics and life plays a decisive role". Using Fluent software on the horizontal axis wind turbine numerical simulation, analysis of the United States of America S809NREL airfoil aerodynamic characteristics of different angles of attack numerical simulation, analyzes the different angles of attack in the vicinity of the pressure, velocity distribution. By solving the two-dimensional unsteady, compressible N-S equations for the calculation of wind turbine airfoil S809used the characteristics of flow around. N-S equation in body-fitted coordinate system is given, with the Poisson equation method to generate the C grid.

scholarly journals Experimental and Numerical Analysis of the Dynamical Behavior of a Small Horizontal-Axis Wind Turbine under Unsteady Conditions: Part I

Machines ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 52 ◽  
Author(s):  
Francesco Castellani ◽  
Davide Astolfi ◽  
Matteo Becchetti ◽  
Francesco Berno
Keyword(s):  
Control System ◽  
Wind Turbine ◽  
Dynamical Behavior ◽  
Urban Environments ◽  
Horizontal Axis ◽  
Test Case ◽  
Complex Flow ◽  
Horizontal Axis Wind Turbine ◽  
Horizontal Axis Wind Turbines ◽  
Unsteady Conditions

An efficient and reliable exploitation of small horizontal-axis wind turbines (HAWT) is a complex task: these kinds of devices actually modulate strongly variable loads with rotational speeds of the order of hundreds of revolutions per minute. The complex flow conditions to which small HAWTs are subjected in urban environments (sudden wind direction changes, considerable turbulence intensity, gusts) make it very difficult for the wind turbine control system to optimally balance the power and the load. For these reasons, it is important to comprehend and characterize the behavior of small HAWTs under unsteady conditions. On these grounds, this work is devoted to the formulation and realization of controlled unsteady test conditions for small HAWTs in the wind tunnel. The selected test case is a HAWT having 3 kW of maximum power and 2 m of rotor diameter: in this work, this device is subjected to oscillating wind time series, with a custom period. The experimental analysis allows therefore to characterize how unsteadiness is amplified moving from the primary resource (the wind) through the rotor revolutions per minute to final output (the power), in terms of delay and amplitude magnification. This work also includes a numerical characterization of the problem, by means of aeroelastic simulations performed with the FAST software. The comparison between experiments and numerical model supports the fact that the fast transitions are mainly governed by the aerodynamic and mechanical parameters: therefore, the aeroelastic modeling of a small HAWT can be useful in the developing phase to select appropriately the design and the control system set up.

Analysis on Aerodynamic Performance of Horizontal Axis Wind Turbine Based on Nonlinear Wake Model

2013 ◽  
Vol 448-453 ◽  
pp. 1716-1720
Author(s):  
Rui Yang ◽  
Jiu Xin Wang ◽  
Sheng Long Zhang
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Optimization Design ◽  
Aerodynamic Performance ◽  
Horizontal Axis ◽  
Wake Vortex ◽  
Horizontal Axis Wind Turbine ◽  
Horizontal Axis Wind Turbines ◽  
Wake Model ◽  
Induced Velocity

A computational method based on nonlinear wake model was established for horizontal axis wind turbines aerodynamic performance prediction. This method makes use of finite difference method to solve the integral differential equation of the model, the induced velocity of wake vortex can be calculated from equations and compared with the induced velocity of wake vortex in linear model. The comparison between the calculated results of wind turbine under axis flow condition, including tip vortex geometry and aerodynamic performance, and available experimental data shows that this method is suitable for wind turbine aerodynamic performance analysis. Finally, a series of numerical calculations were made to investigate the change of wake geometry and aerodynamic performance of the wind turbine when yawing and pitch angle increasing, which provide foundations for aerodynamic optimization design of horizontal axis wind turbines.

Laser Doppler Velocimetry (LDV) measurements of airfoil surface flow on a Horizontal Axis Wind Turbine in boundary layer

Energy ◽  
2019 ◽  
Vol 183 ◽  
pp. 341-357 ◽  
Author(s):  
Qing'an Li ◽  
Jianzhong Xu ◽  
Takao Maeda ◽  
Yasunari Kamada ◽  
Shogo Nishimura ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Wind Turbine ◽  
Laser Doppler Velocimetry ◽  
Surface Flow ◽  
Horizontal Axis ◽  
Laser Doppler ◽  
Doppler Velocimetry ◽  
Horizontal Axis Wind Turbine ◽  
Airfoil Surface

scholarly journals Observation of the Starting and Low Speed Behavior of Small Horizontal Axis Wind Turbine

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Sikandar Khan ◽  
Kamran Shah ◽  
Izhar-Ul-Haq ◽  
Hamid Khan ◽  
Sajid Ali ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Horizontal Axis ◽  
Horizontal Axis Wind Turbine ◽  
Wind Speeds ◽  
Starting Time ◽  
Speed Range ◽  
Horizontal Axis Wind Turbines ◽  
Starting Torque ◽  
High Angles Of Attack

This paper describes the starting behavior of small horizontal axis wind turbines at high angles of attack and low Reynolds number. The unfavorable relative wind direction during the starting time leads to low starting torque and more idling time. Wind turbine models of sizes less than 5 meters were simulated at wind speed range of 2 m/s to 5 m/s. Wind turbines were modeled in Pro/E and based on the optimized designs given by MATLAB codes. Wind turbine models were simulated in ADAMS for improving the starting behavior. The models with high starting torques and less idling times were selected. The starting behavior was successfully improved and the optimized wind turbine models were able to produce more starting torque even at wind speeds less than 5 m/s.

Aerodynamic Optimal Design for Horizontal Axis Wind Turbine Airfoil Using Integrated Optimization Method

2019 ◽  
Vol 16 (08) ◽  
pp. 1841004 ◽  
Author(s):  
Thang Le-Duc ◽  
Quoc-Hung Nguyen
Keyword(s):  
Optimal Design ◽  
Wind Turbine ◽  
Optimization Method ◽  
Aerodynamic Characteristics ◽  
Horizontal Axis ◽  
Aerodynamic Optimization ◽  
Horizontal Axis Wind Turbine ◽  
De Algorithm ◽  
Design Variables ◽  
Wind Turbine Airfoil

In this work, a new approach for aerodynamic optimization of horizontal axis wind turbine (HAWT) airfoil is presented. This technique combines commercial computational fluid dynamics (CFD) codes with differential evolution (DE), a reliable gradient-free global optimization method. During the optimization process, commercial CFD codes are used to evaluate aerodynamic characteristics of HAWT airfoil and an improved DE algorithm is utilized to find the optimal airfoil design. The objective of this research is to maximize the aerodynamic coefficients of HAWT airfoil at the design angle of attack (AOA) with specific ambient environment. The airfoil shape is modeled by control points which their coordinates are design variables. The reliability of CFD codes is validated by comparing the analytical results of a typical HAWT airfoil with its experimental data. Finally, the optimal design of wind turbine airfoil is evaluated about aerodynamic performance in comparison with existing airfoils and some discussions are performed.

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