NREL Phase VI Wind Turbine Modeling Using an Unsteady Panel Method

2014 ◽  
Author(s):  
Eugene Grigoriev ◽  
Iman Borazjani
Keyword(s):  
Wind Turbine ◽  
Pressure Coefficient ◽  
Pressure Profile ◽  
Panel Method ◽  
Rate Of Change ◽  
Inviscid Flows ◽  
Thrust Coefficient ◽  
Pitching Motion ◽  
Unsteady Panel Method ◽  
Nrel Phase Vi

Wind energy production has been increasing steadily in the past decade. The majority of wind power is generated by horizontal axis wind turbines (HAWT). We investigate the modeling of the HAWT using the vortex panel method, which is an inviscid, steady, computationally inexpensive method. Pressure coefficient profiles, calculated by the vortex panel method, were compared to NREL phase VI wind turbine experiments under two different flow conditions. We show that if the flow is not separated over the blade, the vortex panel method can capture the pressure profile on the blade. Furthermore, the panel method has been extended to handle unsteady inviscid flows to investigate the effect of blade oscillations on the power generation, which is not known. The unsteady behavior is modeled by accounting for the time rate of change of circulation. Unsteady effects due to heaving and pitching motion were quantified for different blade oscillation frequencies. It is estimated that the mean thrust coefficient with heaving and pitching motion can be higher than the thrust generated without blade motion in some cases assuming that the flow does not separate.

scholarly journals Propagation of Shock on NREL Phase VI Wind Turbine Airfoil under Compressible Flow

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Mohammad A. Hossain ◽  
Ziaul Huque ◽  
Raghava R. Kammalapati
Keyword(s):  
Shock Waves ◽  
Wind Turbine ◽  
Compressible Flow ◽  
Turbulent Viscosity ◽  
Pressure Coefficient ◽  
Angle Of Attack ◽  
Extreme Condition ◽  
Bottom Surface ◽  
Shock Propagation ◽  
Nrel Phase Vi

The work is focused on numeric analysis of compressible flow around National Renewable Energy Laboratory (NREL) phase VI wind turbine blade airfoil S809. Although wind turbine airfoils are low Reynolds number airfoils, a reasonable investigation of compressible flow under extreme condition might be helpful. A subsonic flow (mach no.M=0.8) has been considered for this analysis and the impacts of this flow under seven different angles of attack have been determined. The results show that shock takes place just after the mid span at the top surface and just before the mid span at the bottom surface at zero angle of attack. Slowly the shock waves translate their positions as angle of attack increases. A relative translation of the shock waves in upper and lower face of the airfoil are presented. Variation of Turbulent viscosity ratio and surface Y+ have also been determined. Ak-ωSST turbulent model is considered and the commercial CFD code ANSYS FLUENT is used to find the pressure coefficient (Cp) as well as the lift (CL) and drag coefficients (CD). A graphical comparison of shock propagation has been shown with different angle of attack. Flow separation and stream function are also determined.

scholarly journals Comparative analysis of numerical computational techniques for determination of the wind turbine aerodynamic performances

2020 ◽  
pp. 175-175
Author(s):  
Bojan Peric ◽  
Aleksandar Simonovic ◽  
Milos Vorkapic
Keyword(s):  
Wind Turbine ◽  
Pressure Coefficient ◽  
Turbine Blades ◽  
Turbulence Models ◽  
Numerical Approach ◽  
Power Coefficient ◽  
Future Research ◽  
Computational Techniques ◽  
Thrust Coefficient ◽  
Aerodynamic Performances

The purpose of this paper is to explore and define an adequate numerical setting for the computation of aerodynamic performances of wind turbines of various shapes and sizes, which offers the possibility of choosing a suitable approach of minimal complexity for the future research. Here, mechanical power, thrust, power coefficient, thrust coefficient, pressure coefficient, pressure distribution along the blade, relative velocity contoure at different wind speeds and streamlines were considered by two different methods: the blade element momentum (BEM) and computational fluid dynamics (CFD), within which three different turbulence models were analyzed. The estimation of the mentioned aerodynamic performances was carried out on two different wind turbine blades. The obtained solutions were compared with the experimental and nominal (up-scaled) values, available in the literature. Although the flow was considered as steady, a satisfactory correlation between numerical and experimental results was achieved. The comparison between results also showed, the significance of selection, regarding the complexity and geometry of the analyzed wind turbine blade, the most appropriate numerical approach for computation of aerodynamic performances.

Three-Dimensional and Rotational Aerodynamics on the NREL Phase VI Wind Turbine Blade

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Alvaro Gonzalez ◽  
Xabier Munduate
Keyword(s):  
Wind Turbine ◽  
Turbine Blade ◽  
Three Dimensional ◽  
Separated Flow ◽  
Leading Edge ◽  
Wind Turbine Blade ◽  
Trailing Edge ◽  
Rotating Blade ◽  
Nrel Phase Vi ◽  
Edge Separation

This work undertakes an aerodynamic analysis over the parked and the rotating NREL Phase VI wind turbine blade. The experimental sequences from NASA Ames wind tunnel selected for this study respond to the parked blade and the rotating configuration, both for the upwind, two-bladed wind turbine operating at nonyawed conditions. The objective is to bring some light into the nature of the flow field and especially the type of stall behavior observed when 2D aerofoil steady measurements are compared to the parked blade and the latter to the rotating one. From averaged pressure coefficients together with their standard deviation values, trailing and leading edge separated flow regions have been found, with the limitations of the repeatability of the flow encountered on the blade. Results for the parked blade show the progressive delay from tip to root of the trailing edge separation process, with respect to the 2D profile, and also reveal a local region of leading edge separated flow or bubble at the inner, 30% and 47% of the blade. For the rotating blade, results at inboard 30% and 47% stations show a dramatic suppression of the trailing edge separation, and the development of a leading edge separation structure connected with the extra lift.

Performance Enhancement Analysis of a Horizontal Axis Wind Turbine by Vortex Trapping Cavity

2021 ◽  
pp. 1-13
Author(s):  
Khaoula Qaissi ◽  
Omer A Elsayed ◽  
Mustapha Faqir ◽  
Elhachmi Essadiqi
Keyword(s):  
Wind Turbine ◽  
Performance Enhancement ◽  
Lift Coefficient ◽  
Separated Flow ◽  
National Renewable Energy Laboratory ◽  
Wake Region ◽  
High Twist ◽  
Horizontal Axis Wind Turbine ◽  
Wind Speeds ◽  
Nrel Phase Vi

Abstract A wind turbine blade has the particularity of containing twisted and tapered thick airfoils. The challenge with this configuration is the highly separated flow in the region of high twist. This research presents a numerical investigation of the effectiveness of a Vortex Trapping Cavity (VTC) on the aerodynamics of the National renewable Energy laboratory (NREL) Phase VI wind turbine. First, simulations are conducted on the S809 profile to study the fluid flow compared to the airfoil with the redesigned VTC. Secondly, the blade is simulated with and without VTC to assess its effect on the torque and the flow patterns. The results show that for high angles of incidence at Rec=106, the lift coefficient increases by 10% and the wake region appears smaller for the case with VTC. For wind speeds larger than 10 m/s, the VTC improves the torque by 3.9%. This is due to the separation that takes place in the vicinity of the VTC and leads to trapping early separation eddies inside the cell. These eddies roll up forming a coherent laminar vortex structure, which in turn sheds periodically out of the cell. This phenomenon favourably reshapes excessive flow separation, reenergizes the boundary layer and globally improves blade torque.

scholarly journals Full field assessment of wind turbine near wake deviation in relation to yaw misalignment

2016 ◽  
Author(s):  
Juan-José Trujillo ◽  
Janna K. Seifert ◽  
Ines Würth ◽  
David Schlipf ◽  
Martin Kühn
Keyword(s):  
Wind Turbine ◽  
Tip Vortex ◽  
Offshore Wind ◽  
Normal Operation ◽  
Offshore Wind Turbine ◽  
Near Wake ◽  
Thrust Coefficient ◽  
Full Field ◽  
Wake Field ◽  
Partial Load

Abstract. Presently there is a lack of data revealing the behaviour of the path followed by the near wake of full scale wind turbines and its dependence on yaw misalignment. Here we present an experimental analysis of the horizontal wake deviation of a 5 MW offshore wind turbine between 0.6 and 1.4 diameters downstream. The wake field has been scanned with a short range lidar and the wake path has been reconstructed by means of two-dimensional Gaussian tracking. We analysed the measurements for rotor yaw misalignments arising in normal operation and during partial load, representing high thrust coefficient conditions. We classified distinctive wake paths with reference to yaw misalignment, based on the nacelle wind vane, in steps of 3° in a range of ±10.5°. All paths observed in the nacelle frame of reference showed a consistent convergence towards 0.9 rotor diameters downstream suggesting a kind of wake deviation delay. This contrasts with published results from wind tunnels which in general report a convergence towards the rotor. The discrepancy is evidenced in particular in a comparison which we performed against published paths obtained by means of tip vortex tracking.

Navier-Stokes and Comprehensive Analysis Performance Predictions of the NREL Phase VI Experiment

2003 ◽  
Author(s):  
Earl P. N. Duque ◽  
Michael D. Burklund ◽  
Wayne Johnson
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Performance Predictions ◽  
Nasa Ames Research ◽  
Nrel Phase Vi ◽  
Wind Turbine Rotor

A vortex lattice code, CAMRAD II, and a Reynolds-Averaged Navier-Stoke code, OVERFLOW-D2, were used to predict the aerodynamic performance of a two-bladed horizontal axis wind turbine. All computations were compared with experimental data that was collected at the NASA Ames Research Center 80-by 120-Foot Wind Tunnel. Computations were performed for both axial as well as yawed operating conditions. Various stall delay models and dynamics stall models were used by the CAMRAD II code. Comparisons between the experimental data and computed aerodynamic loads show that the OVERFLOW-D2 code can accurately predict the power and spanwise loading of a wind turbine rotor.

scholarly journals Utility-Scale Wind Turbine Wake Characterization Using Nacelle-Based Long-Range Scanning Lidar

2014 ◽  
Vol 31 (7) ◽  
pp. 1529-1539 ◽  
Author(s):  
Matthew L. Aitken ◽  
Julie K. Lundquist
Keyword(s):  
Wind Turbine ◽  
Long Range ◽  
Wind Farm ◽  
Thrust Coefficient ◽  
Velocity Deficit ◽  
Scanning Lidar ◽  
Range Scanning ◽  
Utility Scale ◽  
Turbine Wake ◽  
Wind Turbine Wake

Abstract To facilitate the optimization of turbine spacing at modern wind farms, computational simulations of wake effects must be validated through comparison with full-scale field measurements of wakes from utility-scale turbines operating in the real atmosphere. Scanning remote sensors are particularly well suited for this objective, as they can sample wind fields over large areas at high temporal and spatial resolutions. Although ground-based systems are useful, the vantage point from the nacelle is favorable in that scans can more consistently transect the central part of the wake. To the best of the authors’ knowledge, the work described here represents the first analysis in the published literature of a utility-scale wind turbine wake using nacelle-based long-range scanning lidar. The results presented are of a field experiment conducted in the fall of 2011 at a wind farm in the western United States, quantifying wake attributes such as the velocity deficit, centerline location, and wake width. Notable findings include a high average velocity deficit, decreasing from 60% at a downwind distance x of 1.8 rotor diameters (D) to 40% at x = 6D, resulting from a low average wind speed and therefore a high average turbine thrust coefficient. Moreover, the wake width was measured to expand from 1.5D at x = 1.8D to 2.5D at x = 6D. Both the wake growth rate and the amplitude of wake meandering were observed to be greater for high ambient turbulence intensity and daytime conditions as compared to low turbulence and nocturnal conditions.

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