Aerodynamic Model of the Wind Harvest International Model 1500 Wind Turbine

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Dr. Ion Paraschivoiu (with comments by Robert N Thomas, Dr. Farooq Saeed, and Norbert V. Dy)
Publication: IOPARA, Inc.
Year Published: 2009
Resource

This report is a compilation of the aerodynamic analyses of the Wind Harvest International (WHI) wind turbines, Model WHI 530 and WHI 1500, in isolated and multiple configuration settings. The aerodynamic analyses were carried out by IOPARA Inc. as a contract project for WHI from October 2008 to May 2009. The aerodynamic analyses focused on the specific tasks as requested in the project proposal.

 

Aerodynamic Model of the Wind Harvest International Model 3000 Wind Turbine

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Dr. Ion Paraschivoiu (with comments by Robert N Thomas, Dr. Farooq Saeed, and Norbert V. Dy)
Publication: IOPARA, Inc.
Year Published: 2009
Resource

This report is a compilation of the aerodynamic analyses of the Wind Harvest International (WHI) wind turbine Model WHI 3000 at wind speeds < 7.15 m/s (16 mph) in isolated and multiple configuration settings. The aerodynamic analyses were carried out by IOPARA Inc. as a contract project for WHI from August 2009 to October 2009. The aerodynamic analyses focused on the specific tasks as requested in the project proposal.

 

Aerodynamically Interacting Vertical-Axis Wind Turbines: Performance Enhancement and Three-Dimensional Flow

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Ian Brownstein, Nathaniel Wei and John Dabiri
Publication: Energies
Year Published: 2019
Resource

This study examined three-dimensional, volumetric mean velocity fields and corresponding performance measurements for an isolated vertical-axis wind turbine (VAWT) and for co- and counter-rotating pairs of VAWTs with varying incident wind direction and turbine spacings. The purpose was to identify turbine configurations and flow mechanisms that can improve the power densities of VAWT arrays in wind farms. All experiments were conducted at a Reynolds number ofReD=7.3×104. In the paired arrays, performance enhancement was observed for both the upstream and downstream turbines. Increases in downstream turbine performance correlate with bluff–body accelerations around the upstream turbine, which increase the incident freestream velocity on the downstream turbine in certain positions. Decreases in downstream turbine performance are determined by its position in the upstream turbine’s wake. Changes in upstream turbine performance are related to variations in the surrounding flow field due to the presence of the downstream rotor.For the most robust array configuration studied, an average 14% increase in array performance over approximately a50◦range of wind direction was observed. Additionally, three-dimensional vortex interactions behind pairs of VAWT were observed that can replenish momentum in the wake byadvection rather than turbulent diffusion. These effects and their implications for wind-farm design are discussed.

 

CFD Analysis of Vertical Axis Wind Turbines in Close Proximity

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Marius Paraschivoiu, Chad X. Zhang, Selvanayagam Jeyatharsan, Norbert V. Dy, Farooq Saeed, Robert N. Thomas, Ion Paraschivoiu
Publication: IOPARA, Inc.
Year Published: 2011
Resource

This paper presents an analysis based on computational fluid dynamics of vertical axis wind turbines when placed in close proximity in a linear array. It has been noticed that VAWTs placed close to each other with counter rotation motions have a higher coefficient of power than a single turbine. This was termed the “coupled vortex effect”. Two mechanisms have been identified to cause this increase in efficiency: the stream tube contraction effect and the vortex effect. The first is due to the blockage effect from neighboring turbines while the later is related to the neighboring turbine acting as a vortex that induces an increased flow field. This paper analyzes each of these effects and studies the influence of the turbine size and the rotation speed. The change of torque on each blade due to these effects is investigated for two different sizes of wind turbines.

Data Analysis from Experimental Measurements on a Vertical Axis Wind Turbine

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Raphael Coneu
Publication: KTH
Year Published: 2017
Resource

This thesis presents the analysis of the data measured during the test campaign of a vertical axis wind turbine prototype developed by the company Nenuphar Wind in France. Three studies are presented: the study of the loads measured during the test campaign, the study of the vibrations, and the study of the stall conditions on the blades. Focus is put on the methodology of these analyses rather than on their detailed results. The preliminary processing of data is presented in more details, in particular the determination of selection levels asserting the quality of the data, an analysis of the drift of the zero of the loads sensor and an analysis of the cross-talk effects on the same loads sensors. With reference to the experience gained on previous prototypes, the quality of the data acquired on this prototype was greatly improved, allowing the use of stricter selection levels and a better quality of the results. The drift of the zero of the strain gauges was identified to be caused by temperature effects and was corrected on most of the sensors, leading to a significant decrease of the uncertainty on the loads measurements. The analysis of the cross-talks led to the implementation of a new and more precise way of calculation of the uncertainty due to these effects. Finally, the study of the dynamic stall on the blades of the new prototype developed by Nenuphar is described at the end of the report. The comparison with the previous prototype showed similar stall angular ranges, but less stalled rotations were observed on the new prototype than on the previous one.

Efficiency Improvement of Vertical-Axis Wind Turbines with Counter-Rotating Lay-Out

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Nicolas Parneix, Rosalie Fuchs, Alexandre Immas, Frederic Silvert, Paul Deglaire
Publication: EWEA
Year Published: 2016
Resource

Improving the performance of Vertical Axis Wind Turbines (VAWTs) is key to make VAWTs commercially successful. Scientists have investigated several interesting concepts for that purpose: increasing the swept area, especially to limit the losses due to 3D effects, or using flap and pitch systems to control the flow around the blades [1, 2]. Nenuphar, with the Twinfloat concept(see Figure 1), propose to take advantage of all these concepts combined with an aerodynamic effect called counter-rotating effect [3]. The turbine is made of two 2.5MW VAWT on only one floater, to reach a rated power of 5MW. The proximity of the two rotors generates a contraction of the stream tubes that flow in the area between the rotors, thus increasing the air flow rate going through both the swept areas and thereby the performance of the VAWT. This concept has also other advantages:smaller rotors that make easier their fabrication,their installation and Operating and Maintenance (O&M) operations, floater motions reduction thanks to specific control laws and wake reduction leading to an increase in the capacity factor.Simulations presented in this paper are carried out by Computational Fluid Dynamics (CFD) or by a Vortex Panel Method to investigate the stream tubes contraction caused by counter-rotating wind turbines and the impact of the distance between each rotor.This paper presents the main results of this study and the positive impact of counter rotating turbines compared to single turbine performance for floating conditions.

Experimental Validation of Pharwen Code Using Data from VAWT Wind Tunnel Tests with Imposed Motions

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Marianne Dupont, Pitance Denis, Joanna Kluczewska-Bordier, Alexandre Immas, Paul Deglaire
Publication: WindEurope Conference, At Amsterdam
Year Published: 2017
Resource

NENUPHAR, in collaboration with IRT Jules Verne and ECN (Ecole Centrale de Nantes) has performed extensive testing in a large wind tunnel (CSTB, Nantes) of a scaled-model of a two-bladed VAWT in the frame of the “MOQUA” project. The model was mounted on a 6DOF robot (hexapod) capable of imposing simple and combined motions to the structure. The wind turbine was operated at a TSR (tip speed ratio) of about 4 with simulated floater motions (surge, sway, heave, roll, pitch, yaw, and combinations of those). Measurements were carried out using several internal balances placed at the junctions of the rotor elements. Main tests objectives consisted in the validation of the unsteady aerodynamic behavior of the VAWT and in the validation of the PHARWEN numerical code, NENUPHAR’s simulation tool. The experimental validation strategy and results from the comparison between the experiments and the results of numerical simulations are presented in the paper, with a focus on the loads variation over one full rotor revolution that are specific to VAWTs.

Modeling Blade Pitch and Solidities in Straight Bladed VAWTs – Final Report from IOPARA Inc. to Wind Harvest

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: IOPARA Inc.
Publication: Wind Harvest International
Year Published: 2012
Resource

This report is a compilation of the aerodynamic analyses carried out by IOPARA Inc. as part of a contract project called “Modeling Blade Pitch and Solidities in Straight Bladed VAWTs,” realized under the request of Wind Harvest International Inc.

Modeling Blade Pitch and Solidities in Straight Bladed VAWTs – Final Report from Wind Harvest to CEC

Coupled Vortex Effect, Synergy with Tall and Short Turbines
Author: Robert Thomas, Kevin Wolf
Publication: Wind Harvest International
Year Published: 2012
Resource

Final report to the California Energy Commission for the Energy Innovations Small Grant Program awarded to Wind Harvest International in 2012.