FloVAWT: Progress on the Development of a Coupled Model of Dynamics for Floating Offshore Vertical Axis Wind Turbines

2013 ◽  
Author(s):  
Maurizio Collu ◽  
Michael Borg ◽  
Andrew Shires ◽  
Feargal P. Brennan
Keyword(s):  
Experimental Data ◽  
Wind Turbines ◽  
Three Dimensional ◽  
Coupled Model ◽  
Vertical Axis ◽  
Potential Method ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Wind Profiles ◽  
Gyroscopic Effects

In the present article, progress on the development of an aero-hydro-servo-elastic coupled model of dynamics for floating Vertical Axis Wind Turbines (VAWTs) is presented, called FloVAWT (Floating Vertical Axis Wind Turbine). Aerodynamics is based on Paraschivoiu’s Double-Multiple Streamtube (DMST) model [1] [2], relying on blade element momentum (BEM) theory, but also taking into account three-dimensional effects, dynamic stall, and unsteady wind profiles and platform motions. Hydrodynamics is modelled with a time domain seakeeping model [3], based on hydrodynamic coefficients estimated with a frequency analysis potential method. In this first phase of the research program, the system is considered a rigid body. The mooring system is represented through a user defined force-displacement relationship. Due to the lack of experimental data on offshore floating VAWTs, the model has initially been validated by taking each module separately and comparing it against known experimental data, showing good agreement. The capabilities of the program are illustrated through a case study, giving an insight on the relative importance of aerodynamics loads and gyroscopic effects with respect to hydrodynamic load effects.

An Unsteady Prescribed Wake Model for Vertical Axis Wind Turbines

1994 ◽  
Vol 208 (1) ◽  
pp. 13-20 ◽  
Author(s):  
F N Coton ◽  
D Jiang ◽  
R A McD Galbraith
Keyword(s):  
Wind Turbines ◽  
Performance Prediction ◽  
Three Dimensional ◽  
Vortex Method ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Prediction Scheme ◽  
Wake Model ◽  
New Formulation

This paper describes the development of a fully unsteady three-dimensional aerodynamic performance prediction scheme for vertical axis wind turbines (VAWTs). The method is based on the prescribed wake approach of Basuno in which the turbine is represented by a series of bound vortex segments from which emanates a wake consisting of shed and trailing vorticity filaments. Unlike a free vortex method, these wake filaments are constrained to follow a predetermined path, the shape of which is dictated by momentum considerations. By coupling this technique with the unsteady aerofoil performance method of Leishman and Beddoes, a fully unsteady V AWT model is developed. The difficulties associated with coupling the two techniques are discussed and a new formulation for the tangential blade force is introduced. The resulting calculation scheme is shown to agree well with field data from a straight bladed vertical axis wind turbine, even at very low tip speed ratios.

Vertical axis wind turbine operation in icing conditions: A review study

2021 ◽  
pp. 0309524X2110618
Author(s):  
Syed Abdur Rahman Tahir ◽  
Muhammad Shakeel Virk
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Electricity Production ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Horizontal Axis Wind Turbines ◽  
Promising Solution ◽  
Review Study ◽  
Accretion Physics

Vertical Axis Wind Turbine (VAWT) can be a promising solution for electricity production in remote ice prone territories of high north, where good wind resources are available, but icing is a challenge that can affect its optimum operation. A lot of research has been made to study the icing effects on the conventional horizontal axis wind turbines, but the literature about vertical axis wind turbines operating in icing conditions is still scarce, despite the importance of this topic. This paper presents a review study about existing knowledge of VAWT operation in icing condition. Focus has been made in better understanding of ice accretion physics along VAWT blades and methods to detect and mitigate icing effects.

scholarly journals Aerodynamic improvement of Darrieus wind turbine

2021 ◽  
Vol 897 (1) ◽  
pp. 012001
Author(s):  
Oleg Goman ◽  
Andrii Dreus ◽  
Anton Rozhkevych ◽  
Krystyna Heti
Keyword(s):  
Reynolds Number ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Structural Reliability ◽  
Vertical Axis ◽  
Vertical Wind ◽  
Integral Approach ◽  
Vertical Axis Wind Turbine ◽  
Calculation Algorithm ◽  
Vertical Axis Wind Turbines

Abstract Until recently, vertical-axis wind turbines are less extensively developed in wind energetics. At the same time, there are a number of advantages in turbines of such type like their independence from the change of wind direction, lower levels of aerodynamic and infrasound noises, higher structural reliability (compared to horizontal engines), etc. With these advantages, vertical-axis wind turbines demonstrate promising capacities. Inter alia, the productiveness of such turbines can be refined through the aerodynamic improvement of the structure and comprehensive optimization of the rotor geometry. The main purpose of the presented paper is to aerodynamically improve vertical wind turbine in order to increase the efficiency of wind energy conversion into electricity. Within the framework of the classical theory of impulses, this article presents a study of the effect of variation in Reynolds number on the general energy characteristics of a vertical-axis wind turbine with two blades. The integral approach makes it possible to use a single-disk impulse model to determine the main specific indicators of the system. The power factor was calculated based on the obtained value of the shaft torque factor, which in turn was determined by numerically integrating the total torque generated by the wind turbine. To calculate the test problem, we used the classic NACA airfoils: 0012, 0015, 0018 and 0021. The proposed calculation algorithm makes it possible not to indicate the Reynolds number and corresponding aerodynamic coefficients at the beginning of the calculation, but to recalculate it depending on the relative speed, position of the airfoil and the linear speed of the airfoil around the circumference. Proposed modern design techniques can be helpful for optimization of vertical wind turbines.

Investigation of vertical axis wind turbine airfoil performance in rain

2017 ◽  
Vol 232 (2) ◽  
pp. 181-194 ◽  
Author(s):  
Zhenlong Wu ◽  
Yihua Cao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Meteorological Condition ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Turbine Performance ◽  
Practical Design ◽  
Wind Turbine Airfoil ◽  
Naca 0015

Rainfall is a common meteorological condition that wind turbines may encounter and by which their performance may be affected. This paper comprehensively investigates the effects of rainfall on a NACA 0015 airfoil which is commonly used in vertical axis wind turbines. A CFD-based Eulerian–Lagrangian multiphase approach is proposed to study the static, rotating, and oscillating performances of the NACA 0015 airfoil in rainy conditions. It is found that for the different airfoil movements, the airfoil performance can seriously be deteriorated in the rain condition. Rain also causes premature boundary layer separations and more severe flow recirculations than in the dry condition. These findings seem to be the first open reports on rain effects on wind turbine performance and should be of some significance to practical design.

scholarly journals On mooring line tension and fatigue prediction for offshore vertical axis wind turbines: A comparison of lumped mass and quasi-static approaches

2018 ◽  
Vol 42 (2) ◽  
pp. 97-107 ◽  
Author(s):  
D Cevasco ◽  
M Collu ◽  
CM Rizzo ◽  
M Hall
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Line Tension ◽  
Vertical Axis ◽  
Offshore Wind ◽  
Mooring Line ◽  
Offshore Wind Turbine ◽  
Vertical Axis Wind Turbine ◽  
Lumped Mass ◽  
Vertical Axis Wind Turbines

Despite several potential advantages, relatively few studies and design support tools have been developed for floating vertical axis wind turbines. Due to the substantial aerodynamics differences, the analyses of vertical axis wind turbine on floating structures cannot be easily extended from what have been already done for horizontal axis wind turbines. Therefore, the main aim of the present work is to compare the dynamic response of the floating offshore wind turbine system adopting two different mooring dynamics approaches. Two versions of the in-house aero-hydro-mooring coupled model of dynamics for floating vertical axis wind turbine (FloVAWT) have been used, employing a mooring quasi-static model, which solves the equations using an energetic approach, and a modified version of floating vertical axis wind turbine, which instead couples with the lumped mass mooring line model MoorDyn. The results, in terms of mooring line tension, fatigue and response in frequency have been obtained and analysed, based on a 5 MW Darrieus type rotor supported by the OC4-DeepCwind semisubmersible.

scholarly journals An experimental study of the optimal design parameters of a wind power tower used to improve the performance of vertical axis wind turbines

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879954
Author(s):  
Soo-Yong Cho ◽  
Sang-Kyu Choi ◽  
Jin-Gyun Kim ◽  
Chong-Hyun Cho
Keyword(s):  
Experimental Study ◽  
Optimal Design ◽  
Wind Turbine ◽  
Wind Power ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Design Parameters ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines

In order to augment the performance of vertical axis wind turbines, wind power towers have been used because they increase the frontal area. Typically, the wind power tower is installed as a circular column around a vertical axis wind turbine because the vertical axis wind turbine should be operated in an omnidirectional wind. As a result, the performance of the vertical axis wind turbine depends on the design parameters of the wind power tower. An experimental study was conducted in a wind tunnel to investigate the optimal design parameters of the wind power tower. Three different sizes of guide walls were applied to test with various wind power tower design parameters. The tested vertical axis wind turbine consisted of three blades of the NACA0018 profile and its solidity was 0.5. In order to simulate the operation in omnidirectional winds, the wind power tower was fabricated to be rotated. The performance of the vertical axis wind turbine was severely varied depending on the azimuthal location of the wind power tower. Comparison of the performance of the vertical axis wind turbine was performed based on the power coefficient obtained by averaging for the one periodic azimuth angle. The optimal design parameters were estimated using the results obtained under equal experimental conditions. When the non-dimensional inner gap was 0.3, the performance of the vertical axis wind turbine was better than any other gaps.

Investigation of Self-Starting Capability of Vertical Axis Wind Turbines Using a Computational Fluid Dynamics Approach

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Houston G. Wood ◽  
Paul E. Allaire ◽  
Robert J. Ribando
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Mesh Deformation ◽  
Operating Speed ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Turbine Performance

Vertical axis wind turbines have always been a controversial technology; claims regarding their benefits and drawbacks have been debated since the initial patent in 1931. Despite this contention, very little systematic vertical axis wind turbine research has been accomplished. Experimental assessments remain prohibitively expensive, while analytical analyses are limited by the complexity of the system. Numerical methods can address both concerns, but inadequate computing power hampered this field. Instead, approximating models were developed which provided some basis for study; but all these exhibited high error margins when compared with actual turbine performance data and were only useful in some operating regimes. Modern computers are capable of more accurate computational fluid dynamics analysis, but most research has focused on horizontal axis configurations or modeling of single blades rather than full geometries. In order to address this research gap, a systematic review of vertical axis wind-power turbine (VAWT) was undertaken, starting with establishment of a methodology for vertical axis wind turbine simulation that is presented in this paper. Replicating the experimental prototype, both 2D and 3D models of a three-bladed vertical axis wind turbine were generated. Full transient computational fluid dynamics (CFD) simulations using mesh deformation capability available in ansys-CFX were run from turbine start-up to operating speed and compared with the experimental data in order to validate the technique. A circular inner domain, containing the blades and the rotor, was allowed to undergo mesh deformation with a rotational velocity that varied with torque generated by the incoming wind. Results have demonstrated that a transient CFD simulation using a two-dimensional computational model can accurately predict vertical axis wind turbine operating speed within 12% error, with the caveat that intermediate turbine performance is not accurately captured.

Time-Resolved Experimental Characterization of the Wakes Shed by H-Shaped and Troposkien Vertical Axis Wind Turbines

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Giacomo Persico ◽  
Vincenzo Dossena ◽  
Berardo Paradiso ◽  
Lorenzo Battisti ◽  
Alessandra Brighenti ◽  
...  
Keyword(s):  
Wind Turbines ◽  
Large Scale ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Speed Ratio ◽  
Local Dynamic ◽  
Performance Measurements ◽  
Time Resolved ◽  
Vertical Axis Wind Turbines ◽  
Blade Section

In this paper, the aerodynamics of two vertical axis wind turbines (VAWTs) are discussed, on the basis of a wide set of experiments performed at Politecnico di Milano, Milan, Italy. A H-shaped and a Troposkien Darrieus turbine for microgeneration, featuring the same swept area and blade section, are tested at full-scale. Performance measurements show that the Troposkien rotor outperforms the H-shaped turbine, thanks to the larger midspan section of the Troposkien rotor and to the nonaerodynamic struts of the H-shaped rotor. These features are consistent with the character of the wakes shed by the turbines, measured by means of hot wire anemometry on several surfaces downstream of the models. The H-shape and Troposkien turbine wakes exhibit relevant differences in the three-dimensional morphology and unsteady evolution. In particular, large-scale vortices dominate the tip region of the wake shed by the H-shape turbine; these vortices pulsate significantly during the period, due to the periodic fluctuation of the blade aerodynamic loading. Conversely, the highly tapered shape of the Troposkien rotor not only prevents the onset of tip vortices, but also induces a dramatic spanwise reduction of tip speed ratio (TSR), promoting the onset of local dynamic stall marked by high periodic and turbulent unsteadiness in the tip region of the wake. The way in which these mechanisms affect the wake evolution and mixing process for the two classes of turbines is investigated for different tip speed ratios, highlighting some relevant implications in the framework of wind energy exploitation.

Aerodynamic Factors Affecting Performance of Straight-Bladed Vertical Axis Wind Turbines

2007 ◽  
Author(s):  
Mazharul Islam ◽  
M. Ruhul Amin ◽  
David S.-K. Ting ◽  
Amir Fartaj
Keyword(s):  
Experimental Data ◽  
Wind Turbines ◽  
Angle Of Attack ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Factors Affecting ◽  
Vertical Axis Wind Turbines ◽  
Wide Range ◽  
Flow Curvature ◽  
Factors Affecting Performance

Unlike the conventional aerodynamic applications, the straight-bladed vertical axis wind turbines (VAWTs) operate in a circular motion and encounter a wide range of angle of attacks, especially at low tip speed ratios. When the blade angle of attack remains constant or varies slowly with time, it encounters the static stall. However, when the angle of attack changes rapidly with time, it experiences the dynamic stall which is far more difficult to analyze and predict than the static stall. Furthermore, the blade/blade wake interaction in straight-bladed VAWTs also presents modeling problem. In this paper, all of these aforesaid aerodynamic factors are discussed. It was found that these factors need special attention for designing a self-starting straight-bladed VAWT with optimum performance. A numerical method based on Cascade model, proposed by Hirsch and Mandal [1], that gives reasonable correlation with the experimental data available has been used. The effects of dynamic stall and flow curvature on the performance of a straight-bladed VAWT have been analyzed. It is observed from the analysis that aerodynamic forces due to dynamic stall are higher than those due to static stall. As a result, for the performance prediction of straight-bladed VAWTs, especially for the local forces, there can be substantial differences between the experimental data and the calculated values unless the dynamic stall effect is added.

scholarly journals Parked and Operating Loads Analysis in the Aerodynamic Design of Multi-megawatt-scale Floating Vertical Axis Wind Turbines

2021 ◽  
Author(s):  
Mohammad Sadman Sakib ◽  
D. Todd Griffith
Keyword(s):  
Aspect Ratio ◽  
Wind Turbines ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Lateral Force ◽  
Aerodynamic Design ◽  
Power Performance ◽  
Vertical Axis Wind Turbines ◽  
Design Variables ◽  
Loads Analysis

Abstract. A good understanding of aerodynamic loading is essential in the design of vertical axis wind turbines (VAWTs) to properly capture design loads and to estimate the power production. This paper presents a comprehensive aerodynamic design study for a 5 MW Darrieus offshore VAWT in the context of multi-megawatt floating VAWTs. This study systematically analyzes the effect of different, important design variables including the number of blades (N), aspect ratio (AR) and blade tapering in a comprehensive loads analysis of both the parked and operating aerodynamic loads including turbine power performance analysis. Number of blades (N) is studied for 2- and 3-bladed turbines, aspect ratio is defined as ratio of rotor height (H) and rotor diameter (D) and studied for values from 0.5 to 1.5, and blade tapering is applied by means of adding solidity to the blades towards blade root ends, which affects aerodynamic and structural performance. Analyses were carried out using a three-dimensional vortex model named CACTUS (Code for Axial and Crossflow TUrbine Simulation) to evaluate both instantaneous azimuthal parameters as well as integral parameters, such as loads (thrust force, lateral force, and torque loading) and power. Parked loading is a major concern for VAWTs, thus this work presents a broad evaluation of parked loads for the design variables noted above. This study also illustrates that during the operation of a turbine, lateral loads are on par with thrust loads, which will significantly affect the structural sizing of rotor and platform & mooring components.

Sign in / Sign up

Export Citation Format

Share Document