C.G. Anderson

Bio: C.G. Anderson is an academic researcher. The author has contributed to research in topics: Wake & Turbine. The author has an hindex of 4, co-authored 5 publications receiving 250 citations.

An experimental investigation of wind turbine wakes using Particle Image Velocimetry

Abstract: Determination of the aerodynamic performance of horizontal-axis wind turbines (HAWT) is complicated by problems such as wake deformation effects and free stream turbulence An accurate prediction of the wake structure is a dominant factor for reliable wind turbine aerodynamic prediction codes The technique of Particle Image Velocimetry is used to provide detailed full-field data of the wake geometry in the immediate vicinity of the rotor of a reduced-scale wind turbine The results strongly validate the PIV technique applied to studying wind turbine wakes The potential for this method is significant and can be used to compare wake data from other experiments as well as wake geometries predicted by theoretical models

A comparative laboratory and full-scale study of the near wake structure of a wind turbine

Abstract: The operation of a wind turbine produces a downstream region of reduced wind speed, the so-called wake. The wake constitutes an important factor in determining the siting of turbines in wind farms. The mean wake characteristics, and their relation to the incident wind field and the local topography, are of primary importance for the estimation of available wind energy. The turbulent structure of the wake affects the loading and fatigue of downstream turbine rotors, and dictates the minimum spacing of the machines within a wind fam. In order, then, to achieve satisfactory performance from wind farms, especially in areas of complex terrain, a detailed knowledge of the above wake parameters is required. The present paper describes a recent investigation into the properties of the wake of a three-bladed wind turbine. Measurements were made on both a full-scale machine, and on a replica model in the laboratory, at approximately 1/100 scale. The full-scale experiments were carried out on the Greek island of Samos, by workers from the University of Athens, and were based on comprehensive anemometry measurements. The small-scale experiments were conducted by a research group at the University of Edinburgh, Scotland, using the relatively new technique of particle image velocimetry (PIV). A major objective of the work was to assess the validity of small-scale PIV measurements as a tool for investigating full-scale wind turbine phenomena. If successful, there would be significant attractions in using the PIV method, due to its ability to map the velocity in the entire rotor wake at a given instant PIV vector maps may be processed to yield both bulk wake measurements, such as velocity deficits, or data relating to the detailed structure of the wake, e.g. vorticity measurements. In the present campaign, velocity ratios measured 1.1 diameters (D) downstream of the rotor, ie. in the near wake, were compared, using data from full-scale and model scale.

The wake structure of a wind turbine - comparison between PIV measurements and free-wake calculations

Abstract: Rotor aerodynamic prediction codes remain inaccurate, as many of the features of the wake flow are not yet fully understood, or are simply unknown. In the present work, this problem has been addressed by comparing the results of a sophisticated free-wake numerical code with wake measurements made using the technique of Particle Image Velocirnetry (PIV). Unique images have been obtained at the University of Edinburgh, using PN to capture wake images at model scale. Detailed maps of velocity and vorticity have thus been obtained in the wake of a number of small-scale models. Simultaneously, the sophisticated free-wake numerical code ROVLM has been developed at the University of Stuttgart. The code has been successfully applied in previous aerodynamic and aeroacoustic EU research projects. The aim of this comparison has been to highlight those areas of current theory where wake modelling is weakest.

Large eddy simulation study of fully developed wind-turbine array boundary layers

Abstract: It is well known that when wind turbines are deployed in large arrays, their efficiency decreases due to complex interactions among themselves and with the atmospheric boundary layer (ABL). For wind farms whose length exceeds the height of the ABL by over an order of magnitude, a “fully developed” flow regime can be established. In this asymptotic regime, changes in the streamwise direction can be neglected and the relevant exchanges occur in the vertical direction. Such a fully developed wind-turbine array boundary layer (WTABL) has not been studied systematically before. A suite of large eddy simulations (LES), in which wind turbines are modeled using the classical “drag disk” concept, is performed for various wind-turbine arrangements, turbine loading factors, and surface roughness values. The results are used to quantify the vertical transport of momentum and kinetic energy across the boundary layer. It is shown that the vertical fluxes of kinetic energy are of the same order of magnitude as the power...

Unsteady Aerodynamics Experiment Phase VI: Wind Tunnel Test Configurations and Available Data Campaigns

Abstract: The primary objective of the insteady aerodynamics experiment was to provide information needed to quantify the full-scale, three-dimensional aerodynamic behavior of horizontal-axis wind turbines. This report is intended to familiarize the user with the entire scope of the wind tunnel test and to support the use of the resulting data.

Review of computational fluid dynamics for wind turbine wake aerodynamics

Abstract: This article reviews the state-of-the-art numerical calculation of wind turbine wake aerodynamics. Different computational fluid dynamics techniques for modeling the rotor and the wake are discussed. Regarding rotor modeling, recent advances in the generalized actuator approach and the direct model are discussed, as far as it attributes to the wake description. For the wake, the focus is on the different turbulence models that are employed to study wake effects on downstream turbines.

Survey of modelling methods for wind turbine wakes and wind farms

Abstract: This article provides an overview and analysis of different wake-modelling methods which may be used as prediction and design tools for both wind turbines and wind farms. We also survey the available data concerning the measurement of wind magnitudes in both single wakes and wind farms, and of loading effects on wind turbines under single- and multiple-wake conditions. The relative merits of existing wake and wind farm models and their ability to reproduce experimental results are discussed. Conclusions are provided concerning the usefulness of the different modelling approaches examined, and difficult issues which have not yet been satisfactorily treated and which require further research are discussed. Copyright © 1999 John Wiley & Sons, Ltd.