scholarly journals Aerodynamic Simulations for Floating Darrieus-Type Wind Turbines with Three-Stage Rotors

Inventions ◽  
2020 ◽  
Vol 5 (2) ◽  
pp. 18
Author(s):  
Mohamed Amine Dabachi ◽  
Abdellatif Rahmouni ◽  
Eugen Rusu ◽  
Otmane Bouksour

Growing energy demand is causing a significant decrease in the world’s hydrocarbon stock in addition to the pollution of our ecosystem. Based on this observation, the search for alternative sorts of energy to fossil fuels is being increasingly explored and exploited. Wind energy is experiencing a very important development, and it offers a very profitable opportunity for exploitation since the wind is always available and inexhaustible. Several technical solutions exist to exploit wind energy, such as floating vertical axis wind turbines (F-VAWTs), which provide an attractive and cost-effective solution for exploiting higher resources of offshore wind in deep water areas. Recently, the use of the Darrieus vertical axis wind turbine (VAWT) offshore has attracted increased interest because it offers significant advantages over horizontal axis wind turbines (HAWTs). In this context, this article presents a new concept of floating Darrieus-type straight-bladed turbine with three-stage rotors. A double-multiple stream tube (DMST) model is used for aerodynamic simulations to examine several critical parameters, including, solidity turbine, number of blades, rotor radius, aspect ratio, wind velocity, and rotor height. This study also allows to identify a low solidity turbine (σ = 0.3), offering the best aerodynamic performance, while a two-bladed design is recommended. Moreover, the results also indicate the interest of a variable radius rotor, as well as the variation of the height as a function of the wind speed on the aerodynamic efficiency.

2021 ◽  
Author(s):  
Moshe Zilberman ◽  
Abdelaziz Abu Sbaih ◽  
Ibrahim Hadad

Abstract Wind energy has become an important resource for the growing demand for clean energy. In 2020 wind energy provided more than 6% of the global electricity demand. It is expected to reach 7% at the end of 2021. The installation growth rate of small wind turbines, though, is relatively slow. The reasons we are interested in the small vertical axis wind turbines are their low noise, environmentally friendly, low installation cost, and capable of being rooftop-mounted. The main goal of the present study is an optimization process towards achieving the optimal cost-effective vertical wind turbine. Thirty wind turbine models were tested under the same conditions in an Azrieli 30 × 30 × 90 cm low-speed wind tunnel at 107,000 Reynolds number. The different types of models were obtained by parametric variations of five basic models, maintaining the same aspect ratio but varying the number of bucket phases, the orientation angles, and the gaps between the vanes. The best performing turbine model was made of one phase with two vanes of non-symmetric bipolynomial profiles that exhibited 0.2 power coefficient, relative to 0.16 and 0.13 that were obtained for symmetrical polynomial and the original Savonius type turbines, respectively. Free rotation, static forces and moments, and dynamic moments and power were measured for the sake of comparison and explanation for the variations in performances of different types of turbines. CFD calculations were used to understand the forces and moment behaviors of the optimized turbine.


2020 ◽  
Author(s):  
Ussama Ali ◽  
Mhd Modrek ◽  
Md Islam ◽  
Isam Janajreh

Abstract Wind energy has proved to be a promising sustainable energy source; the energy of wind has been harvested not only for decades but for centuries. It was in the late 19th century that wind energy was used to directly obtain electrical power. Horizontal axis wind turbines (HAWTs) are widely used in commercial applications but recently a lot of research is being done on vertical axis wind turbines (VAWTs) to improve their operation and efficiency. Absence of yaw mechanism, low noise emission, and low manufacturing, installation and maintenance costs are some of the prominent advantages of VAWT over HAWT. The objective of this study is to evaluate the performance of different blade airfoils and the influence of blade pitching in the operation of VAWT. Blade pitching is widely used in HAWTs and has proven to be very advantageous in terms of output power, but the effect of blade pitching on VAWT has not been widely studied and much less practically implied due to complex functional mechanism. VAWTs with fixed pitch experience continuously varying angle of attack which reduces the power generation. Airfoils tested in this study, for their performance on a VAWT rotor, are Joukowski airfoil (J-15), NACA0012 and NACA4312, furthermore, passive blade pitching was applied to analyze the effect of inoffset and out-offset blade pitching on the performance of the turbine. High fidelity Navier-Stokes computational flow models were applied for the analysis. A 2D unsteady CFD model was constructed to perform the simulations. Power and torque coefficients were evaluated over a varying range of tip speed ratios and a strong correlation of these coefficients was seen with different input parameters, such as airfoil shape, turbine solidity and tip speed ratios. Out-offset blade pitch angles showed better results than in-offset blade pitch angles.


Author(s):  
Sukanta Roy ◽  
Ujjwal K. Saha

Rapid depletion rate of fossil fuels with an increasing energy demand and their high emission are imposing the evolution activities in the arena of renewable energy. To meet the future demands of renewable energy sources, wind energy is a very promising concept. In this feature, the drag based vertical axis wind turbines (VAWTs) are suitable for small scale wind energy generation for decentralized locations. However, these turbines have low power and torque coefficients as compared to other wind turbines. Numerous blade shapes have been proposed till now to improve the performance of these turbines. In the present paper, a computational study has been performed to simulate the air-flow over different blade profiles using shear stress transport (SST) k–ω turbulence model. The results obtained are validated with the available experimental data. In the dynamic simulations, the power and torque coefficients are calculated considering the blade arc angle as the variable shape parameter. The effects of drag and lift forces on the variable blade shapes are also studied in static simulations at various angular positions. The present paper tries to demonstrate an effective computational methodology to predict the flow behavior around a drag based VAWT. Through this study, it has been found possible to select an optimal blade shape from the point of its aerodynamic performance.


2021 ◽  
pp. 0309524X2110618
Author(s):  
Syed Abdur Rahman Tahir ◽  
Muhammad Shakeel Virk

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.


2018 ◽  
Vol 42 (2) ◽  
pp. 97-107 ◽  
Author(s):  
D Cevasco ◽  
M Collu ◽  
CM Rizzo ◽  
M Hall

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.


Author(s):  
David Marten ◽  
Juliane Wendler ◽  
Georgios Pechlivanoglou ◽  
Christian Navid Nayeri ◽  
Christian Oliver Paschereit

A double-multiple-streamtube vertical axis wind turbine simulation and design module has been integrated within the open-source wind turbine simulator QBlade. QBlade also contains the XFOIL airfoil analysis functionalities, which makes the software a single tool that comprises all functionality needed for the design and simulation of vertical or horizontal axis wind turbines. The functionality includes two dimensional airfoil design and analysis, lift and drag polar extrapolation, rotor blade design and wind turbine performance simulation. The QBlade software also inherits a generator module, pitch and rotational speed controllers, geometry export functionality and the simulation of rotor characteristics maps. Besides that, QBlade serves as a tool to compare different blade designs and their performance and to thoroughly investigate the distribution of all relevant variables along the rotor in an included post processor. The benefits of this code will be illustrated with two different case studies. The first case deals with the effect of stall delaying vortex generators on a vertical axis wind turbine rotor. The second case outlines the impact of helical blades and blade number on the time varying loads of a vertical axis wind turbine.


Author(s):  
David MacPhee ◽  
Asfaw Beyene

Blade pitch control has been extremely important for the development of Horizontal-Axis Wind Turbines (HAWTs), allowing for greater efficiency over a wider range of operational regimes when compared to rigid-bladed designs. For Vertical-Axis Wind Turbines (VAWTs), blade pitching is inherently more difficult due to a dependence of attack angle on turbine armature location, shaft speed, and wind speed. As a result, there have been very few practical pitch control schemes put forward for VAWTs, which may be a major reason why this wind turbine type enjoys a much lower market share as compared to HAWTs. To alleviate this issue, the flexible, straight-bladed vertical-axis turbine is presented, which can passively adapt its geometry to local aerodynamic loadings and serves as a low-cost blade pitch control strategy increasing efficiency and startup capabilities. Using two-dimensional fluid-structure action simulations, this novel concept is compared to an identical rigid one and is proven to be superior in terms of power coefficient due to decreased torque minima. Moreover, due to the flexible nature of the blades, the morphing turbine achieves less severe oscillatory loadings. As a result, the morphing blade design is expected to not only increase efficiency but also system longevity without additional system costs usually associated with active pitch control schemes.


Author(s):  
David McGrain ◽  
Gerald M. Angle ◽  
Jay P. Wilhelm ◽  
Emily D. Pertl ◽  
James E. Smith

The recent rise in fuel costs and global warming concerns have re-invigorated the search for alternative energy sources. Harnessing energy from the wind is a logical alternative; however the cost and efficiency of current wind turbines is a limiting factor. The use of an augmented Vertical Axis Wind Turbines (VAWTs) may become the superior choice to the more common Horizontal Axis Wind Turbines (HAWTs) that are usually associated with the harvesting of wind energy. HAWTs operate on the same principles as large airplane propellers, while VAWTs operate on lift and/or drag principles like an airplane wing or a sail on a boat. VAWTs are currently being investigated for use with circulation control to increase their potential power output. In this paper, two topics will be presented, a comparison between VAWTs and HAWTs for rotor diameter versus key turbine aspects and the impact of VAWTs on environmental concerns, such as bat and bird populations. The Center for Industrial Research Applications (CIRA) at West Virginia University (WVU) is currently developing a concept utilizing circulation control to increase the lift to drag ratio, maximizing the beneficial forces on the VAWT blade, allowing for improved wind energy production. For the comparison between VAWTs and HAWTs, there are currently 14 companies with a total of 34 wind turbines variations representing VAWTs and 11 companies with a total of 40 wind turbines representing HAWTs. Trend studies of VAWT and HAWT diameters to cut-in-speed, rated velocity, max velocity, power output (<100 kW), and power output (≥100 kW) were created to show the potential of VAWTs. A growing concern with wind energy is the impact on bat and bird populations. It is currently believed that VAWTs reduce the impact of wind energy by altering the interaction with the wind. If these benefits can be proven, then not only are VAWTs potentially more economical, but even more eco-friendly.


2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Dieniar N Ramadhani

Much human energy needs are obtained from fossil fuels. This fossil energy is decreasing day by day. So that the utilization of natural energy such as solar energy, water energy and wind energy is being developed. Wind energy is energy that we can find, so it is very easy to use by using a turbine as the driving force. The vertical axis wind turbine is a type of wind turbine that is easier to apply in places where wind potential is not too large. This research was conducted by means of simulation using Qblade v0.963 software by comparing the influence generated from several numbers of wind turbine rotor blades. From the simulation process, it is known that the wind turbine rotor blades with 4 blades are the wind turbines capable of producing the greatest power, which is 75 Watts at a low TSR. So that in the manufacturing process it does not require large costs, but it still has to be built rigid and solidly.


2021 ◽  
Author(s):  
S M Nazmuz Sakib

Pakistan is one of those countries which has large potential of energy harvest from renewable energy sources and specially from wind. With the surge of global warming, the world is moving towards cleaner and viable sources of energy. Horizontal Axis Wind Turbines (HAWT) currently dominates the most of the wind power farm markets in the world but Vertical Axis Wind Turbines (VAWT) are also capable of harvesting large amounts of energy with benefits over the HAWTS. VAWTS do not need a control system to be pointed in the direction of wind because with its blade in radial arrangement, wind from any direction is useful. In this report, a Straight-Blade VAWT is designed for low speeds and its performance parameters are also identified for which the improvement of the VAWT will be obtained. Self-starting ability of VAWT is also analyzed and stress and vibration analysis will be investigated in ANSYS Fluent.


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