Vertical Axis Wind Turbine Research Articles

Benefit Through Vehicles Passing on Highways in Electrical Power Generation

The turbulent airflow caused by vehicular movement on highways is a source of kinetic energy for wind energy (WE) that can be utilized to power highway lighting and communications. The purpose of the current work is to design, install and measure the extent of benefit from small wind turbines along a Highway (HW) in one of the governorates of Iraq - Dohuk. In this investigation, wind speed measurements are close to a significant HW on the Dohuk-Zakho-Iraq (DZI) Road. The three positional characteristics are examined for the wind turbines' optimal position. These factors are heights above ground level, lateral distances from the road shoulder, and the wind turbines' highway-facing orientation. It is possible to supply electrical power for side lighting of external roads via vertical axis wind turbines (VAWT), which are produced from disturbances in air movement. In addition, a battery pack has been used to store energy to sustain fluctuations caused by stopped vehicle traffic and to ensure load operation in the event of a wind turbine stop. A 500W capacity vertical axis windmill is being worked on. The suggested landscaping technique has generated exceptional and long-lasting effects for a price of under 350 US dollars.

Computational fluid dynamics analysis on performance assessment of Darrieus-type vertical axis wind turbine using NACA0016, NACA0019 and NACA0020 airfoil sections

The efficiency of a vertical-axis wind turbine is remarkably less than a horizontal-axis wind turbine and consequently, the most important challenge of the former one is to enhance its aerodynamic performance. An earlier study shows that the selection of an efficient airfoil shape is an important criterion for enhancing the overall performance of a wind turbine. The objective of the present work is to perform the two-dimensional Computational Fluid Dynamics simulation of Darrieus Vertical axis wind turbine using NACA0016, NACA0019 and NACA0020 airfoils which are neither too thick nor too thin. Furthermore, the performance of these three airfoils is compared with two established airfoils, namely NACA0015 and NACA0018. The result reveals that the overall power coefficient of NACA0019 airfoils resulting from the CFD simulation is significantly higher than that of NACA0015. Therefore, the NACA0019 airfoil may be considered one of the effective alternative airfoils for the Darrieus VAWT. Highlights Simulation of vertical axis wind turbine using NACA0016, NACA0019 and NACA0020 airfoils Unsteady URANS studies are carried out to investigate the performance of the airfoils Among the blade profiles studied in this work, NACA 0019 offers superior fluid mechanical performance

On the use of secondary rotors for vertical axis wind turbine power take‐off

AbstractThis work introduces and explores the use of secondary rotors for vertical axis wind turbine power take‐off. A parametric framework based on optimally designed secondary rotors is developed which calculates the maximum achievable efficiency of power conversion between the primary and secondary rotors. It is shown that practicable rotor designs can convert between 87% and 90% of primary rotor power to the secondary rotors whilst facilitating nacelle mass reductions between 85% and 87% compared to traditional reference turbine drivetrains.

A Numerical Study of Blade Geometry Effects in a Vertical-Axes Wind Turbines

Several geometrical elements influence the aerodynamic properties of the Darrieus vertical axis wind turbines (VAWTs). Many extant studies have examined properties, such as solidity, pitching axis position (x/c), length of chord (c), blade quantity (N), diameter (d) of the rotor, and aspect ratio. However, not many have examined the shape of the airfoil (AF), which is a vital property that remains to be thoroughly investigated. Therefore, this present study used computational fluid dynamics (CFD) to investigate many airfoils blade characteristics, such as blade thickness (BT), maximum camber ratio (MCR), MCR location (MCRL), and air speed (AS), to determine their impact on VAWT performance. The results demonstrate a blade thickness BT of 10 to 12%, MCR of 0 to 22%, and MCRL of 24 to 23% yield a comparatively high coefficient of power, adequate optimal blade rotation to airspeed ratio (TSR), broader operational area, and high band efficiency while air velocities of 15 to 10% yield a comparatively higher power coefficient.

Review of different vertical axis wind turbine modeling methods

Wind energy can be used as an inexhaustible option for human consumption. Wind turbines offer a promising solution for off-grid areas. Darrieus turbine is one of the types of turbines that can be more efficient than other types if it is used by knowing its characteristics. The complex dynamic mechanism of the flow around the machine has led to its aerodynamic optimization problems remaining complex. This article reviews the applied methods in modeling vertical axis turbines and implicitly shows the turbine operation by presenting the results of these methods. Knowing these methods is important because each has its advantages and disadvantages and should be selected depending on the purpose of the research. One of the problems with Darrieus turbines is their poor start-up, which has been little researched so far. Finally, a suitable method that can model the start-up is introduced.

Optimizing Vertical-Axis Wind Turbine Performance and Determining Optimal Velocity and Deflector Configuration Based on Wind Speed

In the realm of wind energy harnessing, Vertical-axis Wind Turbines (VAWTs) have emerged as promising alternatives. However, they face persistent challenges due to their low efficiency and poor self-starting properties. This study addresses these limitations and aims to unlock the full potential of VAWTs by conducting a comprehensive investigation. The focus of this research lies in determining the optimal operating velocities to enhance the performance of Savonius-type VAWTs, leveraging advanced deflectors. The study delves into an in-depth analysis of the optimal deflector distances and angles for the turbine, taking into account different geographical areas with varying wind velocities. To achieve this, a Savonius-type VAWT equipped with advanced wind deflectors was meticulously designed and tested. Utilizing SOLIDWORKS software, sophisticated turbine models were crafted, which were then subjected to rigorous analysis using ANSYS Fluent, Computational Fluid Dynamics (CFD) software. The research methodology involved conducting simulations across a range of wind velocities, spanning from 1 ms-1 to 8 ms-1, and changing the deflector distance from 100 cm to 150 cm from the centre of the turbine, and the deflector angle from 12 to 45 degrees. During the simulations, critical indicators of turbine performance, including moment coefficient, moment, force coefficient, and force acting on the blade, were closely examined. The study uncovered significant variations in the power output of the Savonius-type vertical-axis wind turbine (VAWT) fitted with an advanced deflector system, especially at lower wind speeds. Notably, the study revealed that at different wind velocities, the optimum deflector configuration changed, with the highest energy-generating capacity observed at 1 m/s for the wind turbine equipped with advanced deflectors. Outperforming the turbine lacking a deflector system, this inventive method demonstrates the capacity to notably boost energy generation. This novel method underscores the capacity for substantial improvements in energy production. Additionally, the research offers valuable insights into customized deflector distance and angle combinations, optimizing turbine performance for specific wind velocity ranges. By strategically positioning the deflectors, higher energy output can be achieved, making the VAWT system more adaptable and efficient across diverse wind conditions
 
 Keywords: Vertical-axis wind turbine, Wind deflectors, Computational Fluid Dynamics, SOLIDWORKS, ANSYS Fluent

Integrated energy system scheduling optimization considering vertical-axis wind turbines and thermal inertia in oilfield management areas

Traditional horizontal-axis wind turbines (HAWTs) have limited efficiency in low-wind speed regions. In this paper, an integrated energy system (IES) incorporating vertical-axis wind turbines (VAWTs) is proposed; this IES is located in an oilfield management area, which can utilize the low-wind speed resources more efficiently and improve renewable energy consumption, and it also introduces a demand response model based on thermal inertia (TI), thus smoothing out the volatility caused by the VAWT. Typical output scenarios are obtained through stochastic optimization to deal with wind turbine and photovoltaic output uncertainties, and an optimal scheduling model is proposed to minimize the system operating cost. Finally, a simulation study was conducted in a micro-oilfield management area in Shandong Province, China, to demonstrate the performance of the proposed system. The results show that the IES using a VAWT and TI can increase the renewable energy consumption capacity by 87% over the conventional HAWT system, change the user behavior, increase the economic efficiency by 12%, and achieve the smoothing of load-side fluctuation of electric and thermal loads, peak shaving, and valley filling. This paper provides a feasible solution for an IES in low-wind speed areas.

A Numerical Analysis on the Performance and Optimization of the Savonius Wind Turbine for Agricultural Use

Given the state of the world nowadays, renewable energy is becoming more and more essential rendering wind turbine electricity quite important. Its shape and the fact that the Savonius vertical axis wind turbine runs at relatively low wind speeds with high torque values makes it suitable for practical uses such as that of an irrigation system in agriculture industry. This paper utilizes numerical research with Computational Fluid Dynamics (CFD) to investigate the performance of a vertical-axis wind turbine. The ANSYS CFD program was engaged to construct the simulations during the pre- and post-processing stages. Wind speed remained constant while the angular velocity was altered to enable analysis of the flow through the wind turbine. Because of its mechanical simplicity, the primary profile of a semicircle has remained a typical option for turbines that generate high torque based on drag force. The effects of using elliptical curves and the fluctuation in thickness along the profile chord were both examined in this study. Equivalently, an attempt to optimize the rotor's design was made. After the performance of a numerical simulation, a geometry consisting of simple circle arcs was developed, with a 10.9% improvement in the power coefficient, analogous to prior optimizations with more complicated geometries. The numerical results derived include the torque coefficient evolution throughout a full rotation as well as the distribution of vorticity magnitude at different rotor points.

Adaptive blade pitch control method based on an aerodynamic blade oscillator model for vertical axis wind turbines

In recent decades, the high fatigue loads (mainly derived from the blade normal force fluctuation) and low power coefficient at the low tip speed ratio with high incoming wind speeds have greatly hindered the development of vertical axis wind turbines. Regulating the blade's angle of attack using a pitch control method is an effective way to reduce the blade normal force amplitude and improve the power coefficient. This paper proposes an adaptive blade pitch control method based on an aerodynamic blade oscillator model and studies its performance and control mechanism using the computational fluid dynamics method combined with the dynamics of the aerodynamic oscillator. The results show that the pitch control provides positive performance for most parameter configurations with the power coefficient increased by 105% and the blade normal force amplitude reduced by 29.5% for the best parameter configuration; poor performance with one parameter configuration indicates that the virtual pitch center should not be too close to the acting point of the aerodynamic force, otherwise the flow state transformation will make the pitch variation unsatisfactory; with an appropriate parameter configuration, the adaptive pitch control adaptively decreases the pitch angle amplitude with the tip speed ratio increase and provides positive performance for varying tip speed ratios. The research provides a theoretical basis for the application of the adaptive pitch control on vertical axis wind turbines.

Dynamic responses of a 5 MW semi-submersible floating vertical-axis wind turbine: A model test study in the wave basin

Floating vertical-axis wind turbines (VAWTs) are potential solutions for capturing wind energy due to their potential to lower the cost of energy. In this study, a floating VAWT concept is proposed for a water depth of 42 m, comprising a 5 MW three-bladed H-rotor and a semi-submersible platform. Dynamic response characteristics of the floating VAWT concept are experimentally investigated in the wave basin with a scale ratio of 1:50. To tackle the Reynolds number scaling effect, a performance-scaled rotor (PSR) was first designed to match the thrust and side forces. After calibrating the wind and wave fields, free decay and white noise tests are conducted to identify the properties of the floating VAWT system. Wind and wave tests were then performed to analyze the dynamic responses of the floating VAWT, including platform motions, tower-base bending moment, and mooring line tensions. The results show that wind loads primarily influence the mean values of these responses, the fluctuations of the tower-base bending moment and mooring tension are dominated by three-times-per-revolution (3P), while wave loads mainly affect the oscillations of platform motions. This study provides a basis for validating a coupled numerical model and contributes to revealing dynamic response characteristics of floating VAWTs.

Wind tunnel experimental study on the aerodynamic characteristics of straight-bladed vertical axis wind turbine

ABSTRACT To investigate the effect of structural parameters on the aerodynamic characteristics of a Straight-Bladed Vertical Axis Wind Turbine (SB-VAWT), a 4-bladed SB-VAWT without an intermediate support shaft was designed to allow flexibility in changing structural parameters. Wind tunnel tests were conducted to measure the rotational speed, total lift, drag and torque of the wind turbine with different structural parameters at varying wind speeds. Based on the experimental design and optimisation, the wind turbine achieved the highest rotational speed and optimal power generation when the blades were installed in the forward direction at an installation angle of 10°, an installation radius of 160 mm, and a length of 600 mm. Under these optimal conditions, the speed and power generation characteristics of the wind turbine were tested at different wind speeds These results provide valuable insights for the design and application of similar wind turbines.

Performance improvements of vertical axis wind turbines with modified gurney flaps

Plain Gurney flap (PGF), as a passive flow control method, is widely used to improve the aerodynamic performance. Due to the drag penalty, a novel serrated Gurney flap (SGF) is proposed. The numerical simulation is carried out to investigate the effects of GFs on the aerodynamic performance of the NACA0018 airfoil and an associated two-blade rotor of a H-type Vertical Axis Wind Turbine (VAWT). The height of GF ranges from 1.5% to 6% of the airfoil chord length. The results show that the SGF doesn’t exhibit the same lift enhancement as PGF, but lower drag. When the flap height reaches 6% c, the SGF airfoil has the higher lift-to-drag ratio. The 3%-chord-length height of GFs is employed on the rotor and it implies that both PGF and SGF can enhance the output power of VAWT. SGF has superior performance than GF, especially at the TSR>2.5 conditions. At the optimal TSR=3.0, the output power of SGF turbine is 2.7% higher than that of PGF one. The highest improvement of power can reach 13.3% at TSR=4.0.

Performance optimization of vertical axis wind turbine based on Taguchi method, improved differential evolution algorithm and Kriging model

ABSTRACT The capability of vertical axis wind turbine (VAWT) is influenced by its input parameters. In this paper, for the three-bladed VAWT with the NACA0018 airfoil, three important input parameters, i.e. tip speed ratio (TSR), airfoil chord length (C), and pitch angle (β), are selected to explore their impact on the capability of the VAWT, and then to find the best combination of them. Firstly, 16 sets of experiments are determined according to the Taguchi method and are evaluated using the 2D computational fluid dynamics (CFD) numerical simulation, and further studied with the Analysis of Variance. The consequence shows that the TSR and pitch angle are more critical to the performance of the VAWT. In order to obtain the optimal configuration of these parameters, an intelligent method is further proposed. Firstly, a certain number of design schemes are extracted in the selected space through Latin hypercube sampling (LHS), and then the torque coefficient (C m ) of each design scheme was obtained by 2D CFD simulation, the Kriging model is used to establish the correlation among the input parameters and their corresponding torque coefficient. Finally, the improved differential evolution algorithm (JADE) is used to tackle the Kriging model to get the optimal input parameter values. The results show that when the rotor diameter (D) is 2.5 m, the optimal parameters are TSR is 2.6, C is 0.227 m and β is −2.47°, the performance of the VAWT is further improved by about 4.5% compared with the optimal values obtained by the Taguchi method.

Vertical Axis Turbine Performance at Different Parameters: Effects of Generated Turbulence

The need to increase the energy efficiency and energy harvesting of vertical axis wind turbines is growing as a consequence of the quick expansion in the energy sector. Therefore, it is crucial to comprehend how a turbine operates. In this study, the more often used VAWT—vertical axis wind turbine—has been experimentally evaluated. Various performance graphs have been produced as a result. At various wind speeds, S1014 and S1020 airfoils are employed. Aspect ratio and angle of attack were noted, and the performance of the turbine was investigated in relation to the impact of the current produced by the turbulence generating plate. The subsonic wind tunnel setup utilized during the testing consisted of a 15 W DC motor and a 0.1 Nm torque meter. The findings demonstrated that the S1014 type blade profile was more efficient and boosted performance of the two types.

Research of asymmetric airfoil on aerodynamic characteristics of vertical axis wind turbines

Asymmetric airfoils are commonly used in horizontal axis wind turbines, while symmetrical airfoils are currently the focal point of the researches for most vertical axis wind turbines’ airfoils studies. The purpose of this paper is to research the influence of asymmetric airfoils on the aerodynamic performance of vertical axis wind turbines. The influence of asymmetric airfoils on the aerodynamic characteristics of vertical axis wind turbines is investigated by numerical simulation method. The symmetric airfoils are chosen as NACA0021, while the asymmetric airfoils are chosen as DU97-W-300. Single-blade, 3-blade, different tip speed ratios, and three wind speeds (7, 8, 9 m/s) are set as the parameters. The wind turbine with symmetric airfoils performed better aerodynamically at high tip speed ratios, whereas the wind turbine with asymmetric airfoils performs well at low tip speed ratios. The wind turbine with asymmetric airfoils has outstanding start ability at low wind speeds.

Effect of rotor blade position on Vertical Axis Wind Turbine performance

In this paper a numerical study is presented with the aim of evaluating the performance output of three Vertical Axis Wind Turbine (VAWT) configurations. Here using Computational Fluid Dynamics (CFD) a two-dimensional Multi Reference Frame (MRF) approach has been used to perform steady state simulations. For this purpose an inlet velocity of 4m/s has been used along with rotor blade tip speed ratios (λ) in the range of 0 to 0.6. The effects of varying rotor blade position on the global and local flow fields have been quantified. Furthermore, the influence of rotor blade position on performance has been computed. It has been found that within a typical rotor blade passage, maximum torque is obtained at a unique rotor angle. It can be seen that the torque output of the turbine decreases with an increase in rotor tip speed ratio (λ) for all rotor blade positions. From the data obtained it can be concluded that the VAWT power curve characteristics vary with relative rotor blade position.

Wind Tunnel Experiments on Vertical-Axis Wind Turbines with Straight Blades

This paper gives the experimental performances obtained in a wind tunnel for a flexible experimental model of vertical axis wind turbine (VAWT) with straight blades. The effects of blades arrangement in one or two stages, of setting angle and of blade numbers influences on the output performance were analysed. The results showed that the VAWT developed torque at low speeds is greater when the setting angle of blades is greater but the VAWT developed torque at higher speeds is greater when the setting angles of blades is less.

Developing a digital twin framework for wind tunnel testing: validation of turbulent inflow and airfoil load applications

Abstract. Wind energy systems, such as horizontal-axis wind turbines and vertical-axis wind turbines, operate within the turbulent atmospheric boundary layer, where turbulence significantly impacts their efficiency. Therefore, it is crucial to investigate the impact of turbulent inflow on the aerodynamic performance at the rotor blade scale. As field investigations are challenging, in this work, we present a framework where we combine wind tunnel measurements in turbulent flow with a digital twin of the experimental set-up. For this, first, the decay of the turbulent inflow needs to be described and simulated correctly. Here, we use Reynolds-averaged Navier–Stokes (RANS) simulations with k−ω turbulence models, where a suitable turbulence length scale is required as an inlet boundary condition. While the integral length scale is often chosen without a theoretical basis, this study derives that the Taylor micro-scale is the correct choice for simulating turbulence generated by a regular grid: the temporal decay of turbulent kinetic energy (TKE) is shown to depend on the initial value of the Taylor micro-scale by solving the differential equations given by Speziale and Bernard (1992). Further, the spatial decay of TKE and its dependence on the Taylor micro-scale at the inlet boundary are derived. With this theoretical understanding, RANS simulations with k−ω turbulence models are conducted using the Taylor micro-scale and the TKE obtained from grid experiments as the inlet boundary condition. Second, the results are validated with excellent agreement with the TKE evolution downstream of a grid obtained through hot-wire measurements in the wind tunnel. Third, the study further introduces an airfoil in both the experimental and the numerical setting where 3D simulations are performed. A very good match between force coefficients obtained from experiments and the digital twin is found. In conclusion, this study demonstrates that the Taylor micro-scale is the appropriate turbulence length scale to be used as the boundary condition and initial condition to simulate the evolution of TKE for regular-grid-generated turbulent flows. Additionally, the digital twin of the wind tunnel can accurately replicate the force coefficients obtained in the physical wind tunnel.

Electric Power Generation Using Buoyancy-Induced Vortices

Thermally-stratified air layers over solar-heated ground are exploited for scalable, low-cost power generation by the deliberate formation of intense buoyancy-induced vertical columnar vortices. Such vortices entrain the ground-heated air layer in regions with high surface solar heating rates, and convert the (gravitational) potential energy into “solar-induced wind” with significant kinetic energy. Unlike naturally occurring “dust devil” vortices, these columnar vortices are deliberately triggered and anchored. Each vortex is sustained by continuous entrainment of ground-heated air through an azimuthal array of stationary ground-mounted vertical vanes. Electric power is generated by using the rotational and vertical air motions within the columnar vortex to drive a vertical-axis turbine. Meter-scale laboratory experiments have demonstrated the nucleation, anchoring, and sustainment of strong, buoyancy-driven vortices centered within an azimuthal array of stationary vertical vanes above a controlled thermal ground plane. Outdoor tests of a meter-scale prototype have demonstrated autonomous start-up, formation, anchoring, and sustainment of a buoyancy-induced vortex generated solely by absorbed solar energy.

Optimizing H-Darrieus Wind Turbine Performance with Double-Deflector Design

This study aims to improve an H-Darrieus vertical-axis wind turbine (VAWT) by imposing a novel double-deflector design. A computational fluid dynamics (CFD) model was implemented to examine the aerodynamic characteristics of the VAWT with double deflectors. Geometrics factors related to the locations of the two deflectors were considered, and the orthogonal array based on the Taguchi method was constructed for CFD simulation. The CFD results were further provided as the training data for the artificial neural network (ANN) to forecast the optimal configuration. The results indicate that the performance of a VAWT with a double-deflector design could exceed that of a bare VAWT or that of one using a single deflector. The mean power coefficient for a bare VAWT is 0.37, although it could be much higher with a proper setup using double deflectors. The prediction of ANN analysis is consistent with the result of CFD simulation, in which the difference between the ANN prediction and CFD simulation is generally less than 4.48%. The result confirms the accuracy of the prediction of the optimal VAWT performance with a double-deflector design.