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5 pages, 1014 KiB

Open AccessProceeding Paper

Startup Dynamics of Drag-Based Multibladed Vertical Axis Wind Turbine

by Taimoor Asim and Peter Osame

Eng. Proc. 2024, 71(1), 5; https://doi.org/10.3390/engproc2024071005 - 29 Jul 2024

Cited by 1 | Viewed by 811

A multibladed drag-based Vertical Axis Wind Turbine (VAWT) was developed and its startup dynamics evaluated using wind tunnel tests. The experimental data obtained for the time-based angular position of the rotor shaft at Aberdeen’s average wind speed of 6 m/s show an initial rapid acceleration of the VAWT due to the drag force being exerted on the rotor blades. This acceleration becomes more gradual until the VAWT reaches its peak rotational speed of 85 rpm in 30 s, which corresponds to an operating tip speed ratio (TSR) of 0.42. The operating TSR of the VAWT was found to be 27% higher than previously reported in numerical studies. Full article

(This article belongs to the Proceedings of The 4th Annual Conference Solar and Wind Power)

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11 pages, 2750 KiB

Open AccessArticle

Numerical Investigations on the Transient Aerodynamic Performance Characterization of a Multibladed Vertical Axis Wind Turbine

by Jamie Christie, Thomas Lines, Dillon Simpson, Taimoor Asim, Muhammad Salman Siddiqui and Sheikh Zahidul Islam

Energies 2024, 17(8), 1900; https://doi.org/10.3390/en17081900 - 16 Apr 2024

Viewed by 1528

Abstract

The use of vertical axis wind turbines (VAWTs) in urban environments is on the rise due to their relatively smaller size, simpler design, lower manufacturing and maintenance costs, and above all, due to their omnidirectionality. The multibladed drag-based VAWT has been identified as a design configuration with superior aerodynamic performance. Numerous studies have been carried out in order to better understand the complex aerodynamic performance of multibladed VAWTs employing steady-state or quasi-steady numerical methods. The transient aerodynamics associated with a multibladed VAWT, especially the time–history of the power coefficient of each blade, has not been reported in the published literature. This information is important for the identification of individual blade’s orientation when producing negative torque. The current study aims to bridge this gap in the literature through real-time tracking of the rotor blade’s aerodynamic performance characteristics during one complete revolution. Numerical investigations were carried out using advanced computational fluid dynamics (CFD)-based techniques for a tip speed ratio of 0 to 1. The results indicate that transient aerodynamic characterization is 13% more accurate in predicting the power generation from the VAWT. While steady-state performance characterization indicates a negative power coefficient (Cp) at λ = 0.65, transient analysis suggests that this happens at λ = 0.75. Full article

(This article belongs to the Special Issue Operation and Optimization of Renewable Energy Power System)

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19 pages, 5600 KiB

Open AccessArticle

Effect of Stator Blades on the Startup Dynamics of a Vertical Axis Wind Turbine

by Taimoor Asim, Dharminder Singh, M. Salman Siddiqui and Don McGlinchey

Energies 2022, 15(21), 8135; https://doi.org/10.3390/en15218135 - 31 Oct 2022

Cited by 6 | Viewed by 3509

Abstract

Vertical Axis Wind Turbines (VAWTs) are omni-directional, low-cost, low-efficiency wind power extractors. A conventional drag-based VAWT consists of multiple thin rotor blades with a typical peak Tip Speed Ratio (λ) of < 1. Their lower cut-in speed and maintenance cost make them ideal for power generation in urban environments. Numerous studies have been carried out analysing steady operation of VAWTs and quantifying their performance characteristics, however, minimal attention has been paid to their start-up dynamics. There are a few recent studies in which start-up dynamics of lift-based VAWTs have been analysed but such studies for drag-based VAWTs are severely limited. In this study, start-up dynamics of a conventional multi-blade drag-based VAWT have been numerically investigated using a time-dependant Computational Fluid Dynamics (CFD) solver. In order to enhance the start-up characteristics of the drag-based VAWT, a stator has been integrated in the design assembly. The numerical results obtained in this study indicate that an appropriately designed stator can significantly enhance the start-up of a VAWT by directing the flow towards the rotor blades, leading to higher rotational velocity (ω) and λ. With the addition of a stator, the flow fields downstream the VAWT becomes more uniform. Full article

(This article belongs to the Special Issue Modeling and Simulation of Floating Offshore Wind Farms)

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22 pages, 63856 KiB

Open AccessArticle

Numerical and Experimental Study of the Blade Profile of a Savonius Type Rotor Implementing a Multi-Blade Geometry

by Luis A. Gallo, Edwin L. Chica, Elkin G. Flórez and Felipe A. Obando

Appl. Sci. 2021, 11(22), 10580; https://doi.org/10.3390/app112210580 - 10 Nov 2021

Cited by 7 | Viewed by 2852

Abstract

In the present study, the implementation of multi-blade profiles in a Savonius rotor was evaluated in order to increase the pressure in the blade’s intrados and, thus, decrease motion resistance. The geometric proportions of the secondary element were determined, which maximized the rotor’s performance. For this, the response surface methodology was used through a full factorial experimental design and a face-centered central composite design, consisting of three factors, each with three levels. The response variable that was sought to be maximized was the power coefficient (

C_{P}

), which was obtained through the numerical simulation of the geometric configurations resulting from the different treatments. All geometries were studied under the same parameters and computational fluid dynamics models through the ANSYS Fluent software. The results obtained through both experimental designs showed a difference of only 1.06% in the performance estimates using the regression model and 3.41% when simulating the optimal proportions geometries. The optimized geometry was characterized by a

C_{P}

of 0.2948, which constitutes an increase of 10.8% in its performance compared to the profile without secondary elements and of 51.2% compared to the conventional semicircular profile. The numerical results were contrasted with experimental data obtained using a wind tunnel, revealing a good degree of fit. Full article

(This article belongs to the Topic Repowering of Wind Farms)

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