Nondimensional Parameters’ Effects on Hybrid Darrieus–Savonius Wind Turbine Performance

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Armin Roshan ◽  
Amir Sagharichi ◽  
Mohammad Javad Maghrebi
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Power Output ◽  
Urban Areas ◽  
Model Performance ◽  
Vertical Axis ◽  
Favorable Effect ◽  
Turbine Performance ◽  
Primary Model ◽  
Overlap Ratio

Abstract Vertical axial wind turbines are the most commonly used turbines in residential and urban areas. This paper investigates the effect of combining Darrieus and Savonius wind turbines on power output and introduces a wind turbine with high starting torque addition to the wide working domain. A two-dimensional computational fluid dynamics transient simulation is developed, and a moving mesh is implemented for rotating moving parts. Comprehensive research has been carried out to investigate the effects of the initial overlap ratio (ɛ), arc angle Ø, and curvature (α) of Savonius blades on the performance of the turbine and 18 models are simulated at seven tip speed ratios. The results showed that combining the Darrieus turbine with the Savonius turbine has a favorable effect on self-starting performance. Also, it was observed that by changing each of the parameters, the primary model performance could be significantly improved. Finally, it is concluded that ɛ = 0.25, α = 0.25, and ∅ = 150 deg are the optimum values of the parameters which increase turbine power output compared to conventional vertical-axis turbines.

scholarly journals Numerical Investigation of the Savonius Vertical Axis Wind Turbine and Evaluation of the Effect of the Overlap Parameter in Both Horizontal and Vertical Directions on Its Performance

Symmetry ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 821 ◽  
Author(s):  
Mohammad Ebrahimpour ◽  
Rouzbeh Shafaghat ◽  
Rezvan Alamian ◽  
Mostafa Safdari Shadloo
Keyword(s):  
Wind Turbine ◽  
Urban Areas ◽  
Weather Conditions ◽  
Vertical Axis ◽  
Power Coefficient ◽  
External Diameter ◽  
Vertical Axis Wind Turbine ◽  
Complex Process ◽  
Overlap Ratio ◽  
Volume Method

Exploiting wind energy, which is a complex process in urban areas, requires turbines suitable for unfavorable weather conditions, in order to trap the wind from different directions; Savonius turbines are suitable for these conditions. In this paper, the effect of overlap ratios and the position of blades on a vertical axis wind turbine is comprehensively investigated and analyzed. For this purpose, two positive and negative overlap situations are first defined along the X-axis and examined at the different tip speed ratios of the blade, while maintaining the size of the external diameter of the rotor, to find the optimum point; then, the same procedure is done along the Y-axis. The finite volume method is used to solve the computational fluid dynamics. Two-dimensional numerical simulations are performed using URANS equations and the sliding mesh method. The turbulence model employed is a realizable K-ε model. According to the values of the dynamic torque and power coefficient, while investigating horizontal and vertical overlaps along the X- and Y-axis, the blades with overlap ratios of HOLR = +0.15 and VOLR = +0.1 show better performances when compared to other corresponding overlaps. Accordingly, the average Cm and Cp improvements are 16% and 7.5%, respectively, compared to the base with a zero overlap ratio.

Investigation of vertical axis wind turbine airfoil performance in rain

2017 ◽  
Vol 232 (2) ◽  
pp. 181-194 ◽  
Author(s):  
Zhenlong Wu ◽  
Yihua Cao
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Meteorological Condition ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Turbine Performance ◽  
Practical Design ◽  
Wind Turbine Airfoil ◽  
Naca 0015

Rainfall is a common meteorological condition that wind turbines may encounter and by which their performance may be affected. This paper comprehensively investigates the effects of rainfall on a NACA 0015 airfoil which is commonly used in vertical axis wind turbines. A CFD-based Eulerian–Lagrangian multiphase approach is proposed to study the static, rotating, and oscillating performances of the NACA 0015 airfoil in rainy conditions. It is found that for the different airfoil movements, the airfoil performance can seriously be deteriorated in the rain condition. Rain also causes premature boundary layer separations and more severe flow recirculations than in the dry condition. These findings seem to be the first open reports on rain effects on wind turbine performance and should be of some significance to practical design.

Computational Investigation of a Shrouded Vertical Axis Wind Turbine

2016 ◽  
Author(s):  
K. Vafiadis ◽  
H. Fintikakis ◽  
I. Zaproudis ◽  
A. Tourlidakis
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Urban Areas ◽  
Numerical Study ◽  
Flow Analysis ◽  
Vertical Axis ◽  
Green Energy ◽  
Vertical Axis Wind Turbine ◽  
Wide Range ◽  
Small Wind Turbines

In urban areas, it is preferable to use small wind turbines which may be integrated to a building in order to supply the local grid with green energy. The main drawback of using wind turbines in urban areas is that the air flow is affected by the existence of nearby buildings, which in conjunction with the variation of wind speed, wind direction and turbulence may adversely affect wind energy extraction. Moreover, the efficiency of a wind turbine is limited by the Betz limit. One of the methods developed to increase the efficiency of small wind turbines and to overcome the Betz limit is the introduction of a converging – diverging shroud around the turbine. Several researchers have studied the effect of shrouds on Horizontal Axis Wind Turbines, but relatively little research has been carried out on shroud augmented Vertical Axis Wind Turbines. This paper presents the numerical study of a shrouded Vertical Axis Wind Turbine. A wide range of test cases, were examined in order to predict the flow characteristics around the rotor, through the shroud and through the rotor – shroud arrangement using 3D Computational Fluid Dynamics simulations. The power output of the shrouded rotor has been improved by a factor greater than 2.0. The detailed flow analysis results showed that there is a significant improvement in the performance of the wind turbine.

Investigation of Self-Starting Capability of Vertical Axis Wind Turbines Using a Computational Fluid Dynamics Approach

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Alexandrina Untaroiu ◽  
Houston G. Wood ◽  
Paul E. Allaire ◽  
Robert J. Ribando
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Mesh Deformation ◽  
Operating Speed ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Turbine Performance

Vertical axis wind turbines have always been a controversial technology; claims regarding their benefits and drawbacks have been debated since the initial patent in 1931. Despite this contention, very little systematic vertical axis wind turbine research has been accomplished. Experimental assessments remain prohibitively expensive, while analytical analyses are limited by the complexity of the system. Numerical methods can address both concerns, but inadequate computing power hampered this field. Instead, approximating models were developed which provided some basis for study; but all these exhibited high error margins when compared with actual turbine performance data and were only useful in some operating regimes. Modern computers are capable of more accurate computational fluid dynamics analysis, but most research has focused on horizontal axis configurations or modeling of single blades rather than full geometries. In order to address this research gap, a systematic review of vertical axis wind-power turbine (VAWT) was undertaken, starting with establishment of a methodology for vertical axis wind turbine simulation that is presented in this paper. Replicating the experimental prototype, both 2D and 3D models of a three-bladed vertical axis wind turbine were generated. Full transient computational fluid dynamics (CFD) simulations using mesh deformation capability available in ansys-CFX were run from turbine start-up to operating speed and compared with the experimental data in order to validate the technique. A circular inner domain, containing the blades and the rotor, was allowed to undergo mesh deformation with a rotational velocity that varied with torque generated by the incoming wind. Results have demonstrated that a transient CFD simulation using a two-dimensional computational model can accurately predict vertical axis wind turbine operating speed within 12% error, with the caveat that intermediate turbine performance is not accurately captured.

scholarly journals Fabrication and Performance Evaluation of Savonious Vertical Axis Wind Turbine for Uncertain Speed Regions

2017 ◽  
Vol 13 (2) ◽  
Keyword(s):  
Performance Evaluation ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Urban Areas ◽  
Vertical Axis ◽  
Design Parameters ◽  
Vertical Axis Wind Turbine ◽  
Horizontal Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
And Performance

The consumption of electricity in urban as well as rural is increasing every day and became an essential commodity for household and industrial purposes. Unfortunately the availability of electrical energy in India is not sufficient to the required demand and it is essential to discover and generate energy from non-conventional sources with cheap cost. On the same time it is necessary to reduce the consumption of conventional sources and to save fuel. Among all the renewable resources, wind is one of the best resources available all the time at free of cost. Especially vertical axis wind turbines (VAWT) are self-starting, omni directional. They require no yaw mechanism to continuously orient towards the wind direction and provide a more reliable energy conversion technology, as compared to horizontal axis wind turbine. Particularly savonius vertical axis wind turbines (SVAWT) are suitable and practically possible at low or uncertain wind speed regimes. They can be fitted on rooftops and also suitable for the urban areas where electricity is not available properly. This project deals with the fabrication and performance evaluation of savonius vertical axis wind turbine using two blade rotor. The amount of power developed by the wind turbine is calculated under theoretical and practical conditions and aerodynamics coefficients are also estimated. And various design parameters of savonious rotor are identified and determined.

CFD Calculation of Wind Turbines Power Variations in Urban Areas

2012 ◽  
Vol 622-623 ◽  
pp. 1084-1088
Author(s):  
Jafar Bazrafshan ◽  
Payam Sabaeifard ◽  
Farid Khalafi ◽  
Majid Jamil
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Power Output ◽  
Urban Areas ◽  
Stokes Equations ◽  
Horizontal Axis ◽  
Navier Stokes ◽  
Horizontal Axis Wind Turbine ◽  
Navier Stokes Equations ◽  
Cfd Method

Integrating wind turbines in urban areas especially over buildings is a new way of producing electricity which is supported in recent years. Wind turbines sited well above the roof of buildings operate in skewed flow. In this paper, to examine variations in efficiency of wind turbines in this condition, two models of H-Rotor and horizontal axis wind turbine analyzed based on axial momentum theory through computer simulations. Simulations conducted through CFD method and k-ε turbulence model was utilized to analyze flow fluctuations in Navier-Stokes equations. Models show that, for an H-Rotor, the optimal power output in tilted flow can be up to two times the power output of horizontal axis wind turbine (HAWT).

Effect of Solidity on Performance of Vertical Axis Wind Turbine Using Constant Chord Reynolds Number

2021 ◽  
Author(s):  
Anirudh P ◽  
Ratna Kishore Velamati ◽  
Srinath K S ◽  
Unnikrishnan D
Keyword(s):  
Reynolds Number ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Cfd Simulation ◽  
Vertical Axis ◽  
Coefficient Of Performance ◽  
Vertical Axis Wind Turbine ◽  
Number Range ◽  
Turbine Performance ◽  
The Impact

Abstract The demand for wind turbines has increased ever since fossil fuels showed signs of quick depletion. Among wind turbines, Vertical Axis Wind Turbine (VAWT) is compact, produces less noise, is omnidirectional, resilient to turbulent flow, and is easy to maintain. The power generated by a VAWT is a function of a non-dimensional geometric parameter known as solidity (s), which is a function of turbine diameter (D), blade chord (c) and the number of blades (n). The present work analyses the impact of solidity (0.12 and 0.18) as a complete non-dimensional parameter on wind turbine performance. Each parameter of solidity is varied, keeping any one of the parameters constant and numerically studied for its performance across a range of tip speed ratios (TSR). For each solidity, six different combinations of VAWT geometric parameters were analyzed. In all the cases, the chord Reynolds number is kept constant. CFD simulation was performed on the Darrieus H-type (NACA0018 airfoil) VAWT. Two dimensional (2D) computational domains are used to study the effect on the turbine’s performance as the solidity studied is less than 0.4. Unsteady Reynolds-Averaged Navier-strokes (URANS) equation is used to solve the CFD model using ANSYS Fluent 19.1 with 4-equation transition SST k-ω for turbulence modelling. The comprehensive study of the turbine performance keeping the turbine operation within a constant Re number range shows the Coefficient of Performance (Cp) overlaps for a given solidity.

scholarly journals MODELING AND SIMULATION OF THE VERTICAL AXIS WIND TURBINE BY QBLADE SOFTWARE

2020 ◽  
Vol 2 (02) ◽  
pp. 181-188
Author(s):  
MERAD ◽  
Asmae BOUANANI ◽  
Mama BOUCHAOUR
Keyword(s):  
Wind Energy ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Urban Areas ◽  
Clean Energy ◽  
Vertical Axis ◽  
Aerodynamic Characteristics ◽  
Simulation Software ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine

The use of wind energy has no harmful effects on the environment. This makes it a clean energy that is a real alternative to the problem of nuclear waste management and greenhouse gas emissions. Vertical axis wind turbines have prospective advantages in the field of domestic applications, because they have proven effectual in urban areas where wind flow conditions are intermittent, omnidirectional, unsteady and turbulent. The wind cannot ensure a regular energy supply without optimising the aerodynamics of the blades. This article presents a reminder about wind energy and wind turbines, especially the VAWT type wind turbines and also gives a presentation on the aerodynamic side of VAWT by studying the geometry and aerodynamic characteristics of the blade profiles with the acting forces and also the explanation of the DMS multiple flow tube model. This work also gives the different simulation methods to optimize the behaviour of the blades from the selected NACA profiles; the analysis first goes through the design of the blades by the design and simulation software Qblade which is used to calculate also the forces on the blade and the coefficients of lift, drag and fineness. At the end of this article we have the DMS simulation of the VAWT turbines, by determining the power coefficient and the power collected by the turbine to select the wind turbine adapted to a well characterized site.

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

2014 ◽  
Vol 554 ◽  
pp. 536-540
Author(s):  
Kadhim Suffer ◽  
Ryspek Usubamatov ◽  
Ghulam Abdul Quadir ◽  
Khairul Azwan Ismail
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Urban Areas ◽  
Fluid Dynamic ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines ◽  
Horizontal Axis Wind Turbines ◽  
The Individual

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.

scholarly journals Analytical and Numerical Solution for H-type Darrieus Wind Turbine Performance at the Tip Speed Ratio of Below One

2020 ◽  
Vol 10 (2) ◽  
pp. 269-281
Author(s):  
Pedram Ghiasi ◽  
Gholamhassan Najafi ◽  
Barat Ghobadian ◽  
Ali Jafari
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Turbine Performance ◽  
Solution Methods ◽  
Time Required

H-type Darrieus vertical axis wind turbines (VAWT) have omnidirectional movement capability and can get more power compared to other VAWTs at high tip speed ratios (𝜆). However, its disadvantages are self-starting inability and low generated power at 𝜆 less than 1. The performance of H-type Darrieus wind turbine at 𝜆<1 was studied using double multiple stream tube (DMST) model and two-dimensional computational fluid dynamic (CFD) simulation. In CFD simulation, the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations were used and the turbulence model was solved with SST k-ω model. The performance of fifteen various wind turbines was determined at fourteen wind velocities by two solution methods. The effect of chord length, solidity, Reynolds number and Height to Diameter (H/D) ratio were investigated on generated torque, power and the time required to reach 𝜆=0.1. Increasing in the moment of inertia due to the increasing in required time to reach 𝜆=0.1. In the low TSRs, the wind turbines can generate higher torque and power in high Re numbers and solidities. The required time was reduced by an increase in Re number and solidity. Finally, the best ratio of H/D of H-type Darrieus wind turbines was defined to improve the turbine performance.

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