Type Vertical Axis Wind Turbine Research Articles

Optimizacija vetroturbine sa vertikalnom osom upotrebom genetskih algoritama i CST parametrizacijom aeroprofila

Darrieus type vertical axis wind turbine (VAWT) is optimized using the genetic algorithm (GA). The airfoil shape is parameterized using the Class-Shape Transformation (CST) method. The double multiple stream tube (DMST) method with the Gormont dynamic stall modification is used for the calculation of the VAWT performance parameters. Once the numerical codes are validated using available experimental results, the airfoil parameters are varied as to achieve the optimum value of the genetic algorithm fitness function.

Effect of blade number on performance of drag type vertical axis wind turbine

The effect of blade number on performance of drag type vertical axis wind turbine (VAWT) is studied by Ansys numerical simulation, it involves 3-blade, 5-blade and 6-blade VAWTs. The optimized width of blade for each VAWT at maximum power efficiency is obtained, and simulation for the wind turbine with different number of blade is conducted for the VAWTs with turbine radius of 2 m at the inlet wind speed 8 m/s. By simulations, it gets the evolution curve of torque with respect to time, and the cyclical characteristics for these wind turbines. The results show that the maximum power efficiency and the stability of the wind turbine increase with the number of blade of the wind turbine, however the optimal d/D decreases with the number of blade of the wind turbine. The maximum power efficiencies are 20.44, 24.30 and 26.82% for 3-blade, 5-blade and 6-blade wind turbines, and the correspondingly optimal d/D are 0.66, 0.40 and 0.35, respectively. While the optimal rotational rate of turbine decreases with blade number.

Numerical Investigation of Modified Bach Type Vertical Axis Wind Turbine

This study evaluates the performance and flow behaviour over the modified Bach type Vertical Axis Wind Turbine. A two dimensional unsteady state analysis is carried out in this study. The unsteady Reynolds Averaged Navier-Stokes equation and the turbulence equation corresponding to SST k-ω turbulence model are solved using commercial software ANSYS FLUENT 13. A grid independence study is performed to choose optimum mesh elements. The simulation is carried out and performance parameters like power coefficient and torque coefficient are calculated. The results are compared with the available experimental data for validation purpose and these matched with numerical values. An improved performance of around 37% Cp is observed for modified Bach type over simple Savonius rotor. Moreover, a brief analysis of flow behaviour over the rotor is studied.

Validation of an Actuator Line Model Coupled to a Dynamic Stall Model for Pitching Motions Characteristic to Vertical Axis Turbines

Vertical axis wind turbines (VAWT) can be used to extract renewable energy from wind flows. A simpler design, low cost of maintenance, and the ability to accept flow from all directions perpendicular to the rotor axis are some of the most important advantages over conventional horizontal axis wind turbines (HAWT). However, VAWT encounter complex and unsteady fluid dynamics, which present significant modeling challenges. One of the most relevant phenomena is dynamic stall, which is caused by the unsteady variation of angle of attack throughout the blade rotation, and is the focus of the present study. Dynamic stall is usually used as a passive control for VAWT operating conditions, hence the importance of predicting its effects. In this study, a coupled model is implemented with the open-source CFD toolbox OpenFOAM for solving the Navier-Stokes equations, where an actuator line model and dynamic stall model are used to compute the blade loading and body force. Force coefficients obtained from the model are validated with experimental data of pitching airfoil in similar operating conditions as an H-rotor type VAWT. Numerical results show reasonable agreement with experimental data for pitching motion.

Starting torque improvement using J-shaped straight-bladed Darrieus vertical axis wind turbine by means of numerical simulation

In this study a 3 kW straight–bladed Darrieus type Vertical Axis Wind Turbine (VAWT) is investigated numerically using OpenFOAM computational fluid dynamic package. The newly proposed J-Shaped profile is used as the blade airfoil in the simulation. The J-Shaped profile is designed by means of eliminating a fraction of pressure side of Du 06-W-200 airfoil. The main purpose of this investigation is the improvement of the VAWT starting torque using J-shaped profile. The power curves for both conventional and J-shaped profiles are calculated and the torque variation is obtained at different azimuth angles. In addition, the vorticity and pressure field surrounding the wind turbine is presented. The results indicate that the performance of turbine is optimized for J-shaped profile which eliminates the pressure side of airfoil from the maximum thickness toward the trailing edge. Moreover, by employing this J-Shaped profile, the wind turbine performance is intensified TSRs and self-starting of turbine is improved.

CFD analysis of three and four blades movable vanes type vertical axis wind turbine having movable vanes

CFD analysis of three and four blades movable vanes type vertical axis wind turbine having movable vanes

Airfoil Design for Vertical Axis Wind Turbine Operating at Variable Tip Speed Ratios

A new airfoil design method for H type vertical axis wind turbine is introduced in the present study. A novel indicator is defined to evaluate vertical axis wind turbine aerodynamic performance at variable tip speed ratios and selected as the airfoil design objective. A mathematic model describing the relationship between airfoil design variables and objective is presented for direct airfoil design on the basis of regression design theory. The aerodynamic performance simulation is conducted by computational fluid dynamics approach validated by a wind tunnel test in the study. Based on the newly developed mathematic model, a new airfoil is designed for a given wind turbine model under constant wind speed of 8 m/s. Meanwhile, the comparison of aerodynamic performance for newly designed airfoil and existing vertical axis wind turbine airfoils is studied. It has been demonstrated that, by the novel indicator, the rotor aerodynamic performance at variable tip speed ratios with the newly designed airfoil is 6.78% higher than the one with NACA0015 which is the airfoil widely used in commercial H type vertical axis wind turbine.

Modeling for the Aerodynamics Analysis of the Four Blades Movable Vanes Type Vertical Axis Wind Turbine (VVAWT)

The power generated by a Vertical Axis Wind Turbine (VAWT) depends on the drag force generated by the individual blades and interactions between them in a rotating configuration. The present Analysis is on attempt to predict numerically the coefficient of drag and other aerodynamic parameters for a four blade Vane type Vertical Axis Wind Turbine (VVAWT) with different blades and vanes position. For numerical investigation, commercial available computational fluid dynamics CFD software GAMBIT and FLUENT are used. In this numerical analysis the Shear Stress Transport (SST) k-ω turbulence model is used which is better than the other turbulence models available as suggested by some researchers. The computed results show good agreement with published experimental results.

Modeling, Simulation, Hardware Implementation of a Novel Variable Pitch Control for H-Type Vertical Axis Wind Turbine

Abstract It is well known that the fixed pitch vertical axis wind turbine (FP-VAWT) has some disadvantages such as the low start-up torque and inefficient output efficiency. In this paper, the variable pitch vertical axis wind turbine (VP-VAWT) is analyzed to improve the output characteristics of FP-VAWT by discussing the force of the six blade H type vertical axis wind turbine (VAWT) under the stationary and rotating conditions using built the H-type VAWT model. First, the force of single blade at variable pitch and fixed pitch is analyzed, respectively. Then, the resultant force of six blades at different pitch is gained. Finally, a variable pitch control method based on a six blade H type VP-VAWT is proposed, moreover, the technical analysis and simulation results validate that the variable pitch method can improve the start-up torque of VAWT, and increase the utilization efficiency of wind energy, and reduce the blade oscillation, as comparable with that of FP-VAWT.

A Performance Comparison of Three Micro-Sized Blade Rotor Designs for Malaysia Wind Speed Condition

Vertical-Axis Wind Turbines (VAWTs) are known as the most suitable wind turbine for small-scale electrical generation. There are many types of VAWTs and each of it has different performances and efficiency. In this work, three types of VAWT systems (Savo-B2, Savo-B4 and Giro-B3) were designed, constructed and tested to investigate the amount of electrical power that could be generated under several constant wind speeds. The blade rotors were designed and built using 2 mm thickness of aluminum plate. The tip speed ratios, power coefficients, blade rotations for each blade rotor and the simplicity of the proposed designs were studied via an experimental setup. The experimental work demonstrates that Savo-B2 provides the highest power coefficient which is up to 0.32. Meanwhile, Giro-B3 offers the fastest rotational blade speed, up to 20.53 rad/s, among the three designs.

Modern small wind turbine design solutions comparison in terms of estimated cost to energy output ratio

This paper presents a series of estimations performed in order to establish the actual cost-effectiveness of three different small wind turbines (SWTs) design solutions. Each of them was evaluated and based on their power curves and installation costs, using wind data from a numerical weather prediction (WNP) model, a return on investment (ROI) period was calculated. The chosen turbines are: a standard three bladed horizontal axis wind turbine (HAWT), an advanced diffuser augmented HAWT and a Darrieus type vertical axis wind turbine (VAWT). The conclusions drawn from this study entertain the idea that from the economical point of view, a price reduction of SWT systems is more important than aerodynamic complexity and efficiency.

An Experimental Study of a Cyclonic Vertical Axis Wind Turbine for Domestic Scale Power Generation

The primary objective of this paper is to investigate a cyclonic domestic scale vertical axis wind turbine with semicircular shaped blades under a range of wind speeds. A 16-bladed rotor was initially designed and itstorques and angular speeds were measured over a range of wind speeds using a wind tunnel. Additionally, a cowling device was developed to enhance the turbine efficiency by directing the air flow from the rear blades into the atmosphere. Another 8-bladed rotor was also manufactured to investigate the effect of blade number on the maximum power generation. The aerodynamic performance of the cowling device wasalso investigated. Maximum power curves as a function of wind speeds were established for each configuration. The results indicated that the 16-bladed wind turbine can be used for domestic scale wind power generation. The results show that the cowling device has positive effect to increase the rotor speed to a significant amount. With the use of the cowling device, the average rotor speed increased by about 26% for the 16-bladed rotor compared to the baseline configuration. A significant increase (about 40%) of rotor speed was also found for the 8-bladed rotor with the cowling device. The results also indicated that the cowling device can be used to increase the power output of this cyclonic type vertical axis wind turbine especially with a reduce number of blades.

Effect of blade installation angle on power efficiency of resistance type VAWT by CFD study

Renewable energy is an inevitable choice to meet the demands of energy resource. In the 21st century, one of the serious problems facings us is the energy resources that restrict the social progress and sustainable development. Environmental pollution and fossil energy resources shortage force people to explore and use new energy resources. The aim of this paper is to study the effect of blade installation angle on power coefficient of a five-blade resistance type vertical axis wind turbine using CFD simulations. The computation is conducted for the turbine with the blade diameter of 0.76–0.86 m and the turbine radius R = 2 m. The results show that the maximum value of power efficiency of 28.48 % can be obtained when the installation angle is 19° for the five-blade resistance type vertical axis wind turbine with the blade diameter of 0.78 m and the turbine radius R = 2 m.

Aerodynamic performance and characteristic of vortex structures for Darrieus wind turbine. II. The relationship between vortex structure and aerodynamic performance

In this paper, transient computational fluid dynamics (CFD) simulations of a straight-bladed Darrieus type vertical axis wind turbine were performed by means of an in-house CFD code. The Spalart-Allmaras turbulence model was implemented in the numerical code for the turbulence. Particular emphasis was placed on effect of interaction between vortices and blades on the aerodynamic performance of the simulated turbine at different tip speed and solidity ratios. The obtained results suggested that vortices were shed from previous blade passages and the close encounter of a rotor blade with these vortices can have a considerable impact on power coefficient of the simulated turbine during operation at different tip speed ratios. As a result, possible reasons for the changes in the behavior of this type of turbine due to the variation of tip speed ratio and solidity were proposed.

Modeling and Numerical Simulation for the Newly Designed Four Cavity Blades Vertical Axis Wind Turbine

The last years have proved that Vertical Axis Wind Turbines (VAWTs) are more suitable for urban areas than Horizontal Axis Wind Turbines (HAWTs). To date, very little has been published in this area to assess good performance and lifetime of VAWTs either in open or urban areas. The main goal of this current research is to investigate numerically the aerodynamic performance of a newly designed cavity type vertical axis wind turbine having four blades. In the current new design the power generated depends on the drag force generated by the individual blades and interactions between them in a rotating configuration. For numerical investigation, commercially available computational fluid dynamic CFD software GAMBIT and FLUENT were used. In this numerical analysis the Shear Stress Transport (SST) k-ω turbulence model is used which is better than the other turbulence models available as suggested by some researchers. The computed results show good agreement with published experimental results.

Predicting Double-Blade Vertical Axis Wind Turbine Performance by a Quadruple-Multiple Streamtube Model

Abstract Double-blade vertical axis wind turbines (DB-VAWTs) can improve the self-starting performance of lift-driven VAWTs. We here propose the quadruple-multiple streamtube model (QMS), based on the blade element momentum (BEM) theory, for simulating DB-VAWT performance. Model validity is investigated by comparison to computational fluid dynamics (CFD) prediction for two kinds of two-dimensional DB-VAWT rotors for two rotor scales with three inner-outer radius ratios: 0.25, 0.5, and 0.75. The BEM-QMS model does not consider the effects of an inner rotor on the flow speed in the upwind half of the rotor, so we introduce a correction factor for this flow speed. The maximum power coefficient predicted by the modified BEM-QMS model for a DB-VAWT is thus closer to the CFD prediction. Keywords : Wind turbine, Double-blade rotor, VAWT, BEM, CFD, QMS. 1. Introduction Vertical axis wind turbines (VAWTs) offer lower costs due to the simplified mechanics, because the wind direction is unimportant to performance. However, small-scale lift-driven VAWTs typically have poor self-starting performance [1]. Therefore, a variety of steps have been tried to improve self-starting performance: increasing blade chord length, adding more blades, using drag-driven wind turbines as a starter, and designing blade airfoils for high aerodynamic performance (for example, [2]). Double-blade vertical axis wind turbines (DB-VAWTs), such as the one shown in Fig. 1 (a), are an example for improving self-starting performance. DB-VAWTs can produce larger starting torque than conventional single-rotor VAWTs with the same blade chord length. Figure 1(b) shows a new type of VAWT with multiple looped blades forming a double-blade rotor structure, as in a DB-VAWT. This VAWT was named the butterfly wind turbine (BWT) [3] because as it rotates around the vertical axis it has the shape of a butterfly. The BWT may offer reduced costs, good self-starting performance, high energy efficiency, and good vibration handling because of the direct installation of the armless looped blades on the central axis. Although propeller-type horizontal axis wind turbines (HAWTs) are the primary turbines for large-scale wind power generation, large-scale VAWTs have been recently proposed and developed for offshore wind power because of their low operational and maintenance costs [4]–[10]. A large-scale VAWT requires struts or arms that connect the blades and central rotating axis, and the cross-section of the struts should also be airfoils to reduce drag. These airfoil struts produce lift force if they incline against the horizontal plane, and so the structure can be regarded as a partial double-blade rotor. Since the flow field of a double-blade rotor is very complex, it is difficult to predict performance by using conventional blade

Numerical Investigation on the Flow Noise Characteristics of the Hybrid Vertical-axis Wind Turbine

본 논문에서는 복합형 수직축 풍력발전기의 유동소음특성에 관한 연구를 수행하였다. 복합형 수직축 풍력발전기는 Savonius형과 Darrieus형을 동시에 사용하여 두 풍력발전기의 장점을 극대화하여 단점을 상쇄시키는 새로운 개념의 수직축 풍력발전기이다. 본 연구에서는 이러한 특성을 갖는 복합형 수직축 풍력발전기에 대하여, 복합 전산공력음향학 기법을 이용하여 풍력발전기에서 발생하는 유동소음을 예측하였다. 먼저, 전산유체역학 기법을 이용하여 터빈 주위의 비정상유동장을 예측하였다. 다음으로, 예측한 비정상유동장에 음향상사법을 적용하여 터빈으로부터 방사하는 유동소음을 예측하였다. 해석결과를 바탕으로 복합형 수직축 풍력발전기의 유동소음특성을 분석하였고, 이를 Savonius형 및 Darrieus형의 유동소음특성과 비교하였다. In this paper, flow noise characteristics of the hybrid vertical-axis wind turbine is investigated. Hybrid vertical-axis wind turbines consisting of two types of vertical-axis wind turbines, Savonius and Darrieus, are devised to maximize merits of one turbine and thus minimize demerits of the other turbine. In order to predict flow noise radiating from hybrid vertical-axis wind turbines, hybrid computatioinal aero acoustic techniques are used. First, unsteady flow fields around the turbine are predicted using computational fluid dynamics method. Then, the flow noise radiations from the turbines are predicted by applying acoustic analogy to the predicted flow fields. Based on numerical results, noise characteristics of a hybrid vertical-axis wind turbine is investigated and is compared with those of Savonius and Darrieus wind turbines.

A Numerical Study on a Vertical-Axis Wind Turbine with Inclined Arms

This work focuses on a particular type of vertical-axis wind turbine, in which a number of inclined arms with airfoil-shaped cross-sections are mounted to connect the principal blades to their hub. While the majority of the known studies on vertical-axis turbines is devoted to the role of principal blades, in most of the cases without taking into account other parts of the wind turbine, the objective of this work is to investigate the effect of uncommon arm geometries, such as the inclined arms. The inclined arms are known to have a potentially beneficial role in the power extraction from the wind current but, due to the complexity of the phenomena, the investigation on aerodynamics of this type of turbine is often impossible through analytical models, such as blade-element momentum theory. It turns out that adequate studies can only be carried out by wind tunnel experiments or CFD simulations. This work presents a methodical CFD study on how inclined arms can be used on a selected wind turbine configuration to harvest additional power from the wind. The turbine configuration, geometry, and some fundamental definitions are introduced first. Then an in-depth CFD analysis is presented and discussed.

Effect of moment of inertia to H type vertical axis wind turbine aerodynamic performance

The main aerodynamic performances (out power out power coefficient torque torque coefficient and so on) of H type Vertical Axis wind Turbine (H-VAWT) which is rotating machinery will be impacted by moment of inertia. This article will use NACA0018 airfoil profile to analyze that moment of inertia through impact performance of H type VAWT by utilizing program of Matlab and theory of Double-Multiple Streamtube. The results showed that the max out power coefficient was barely impacted when moment of inertia is changed in a small area,but the lesser moment of inertia's VAWT needs a stronger wind velocity to obtain the max out power. The lesser moment of inertia's VAWT has a big out power coefficient, torque coefficient and out power before it gets to the point of max out power coefficient. Out power coefficient, torque and torque coefficient will obviously change with wind velocity increased for VAWT of the lesser moment of inertia.

200 W급 자이로밀형 수직축 풍력터빈 로터 블레이드 형상설계 및 유동해석

This study is focused on the shape design and flow analysis on a 200 W-class Gyromill type vertical axis wind turbine rotor blade. Single tube theory is adopted for the shape design of the turbine blade. 2-dimensional CFD analysis is conducted to examine the turbine performance with basic shape, and then 3-dimensional shape is determined from the examination of the performance. By the CFD analysis on the 3-dimensional shape of the wind turbine, performance of the turbine is examined and also, shape of the wind turbine rotor blade is determined accordingly. From the results of this study, a 200 W-class Gyromill type vertical axis wind turbine rotor blade is designed and the reliability of the design method is confirmed by CFD analysis.