Computational Analysis of Airfoil Merging and its Effect on Performance of Lift Based Vertical Axis Wind Turbine

Low Wind Speed ◽

Naca 0012 ◽

Selection Of

In regions of low wind speed, overcoming the starting torque of a Vertical Axis Wind Turbine (VAWT) becomes a challenge aspect. In order to overcome this adversity, careful selection of airfoils for the turbine blades becomes a priority. This paper tries to address the issue utilizing an approach wherein by observing the effect of merging two airfoils. Two airfoils which are of varying camber and thickness are merged and their aerodynamic characteristics are evaluated using the software XFOIL 6.96. For a variation in angle of attack from 0 to 90°, aerodynamic analysis is done in order to observe the behavior of one quarter of the entire VAWT cycle. An objective function is developed so as to observe the maximum possible torque generated by these airfoils at Reynolds number varying from 15,000–120,000. Due to change in the value of CL observed at Low Reynolds Number using commercial CFD softwares, multiple objective functions are utilized to observe the behavior over a range of Reynolds number. An experimental co-relation between the cut-in velocity and the lift-coefficient of the airfoils is developed in order to predict the cut-in velocity of the interpolated airfoils. The airfoils used for this paper are NACA 0012, NACA 0018, FX 66 S196, Clark Y (smooth), PT 40, SD 7032, A 18, SD 7080, SG 6043 and SG 6040.

Numerical Studies on the Effect of Cambered Airfoil Blades on Self-Starting of Vertical Axis Wind Turbine Part 1: NACA 0012 and NACA 4415

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.787.250 ◽

2015 ◽

Vol 787 ◽

pp. 250-254 ◽

Cited By ~ 2

Author(s):

T. Micha Premkumar ◽

Sivamani Seralathan ◽

T. Mohan ◽

N.N.P. Saran Reddy

Keyword(s):

Wind Turbine ◽

Turbine Blades ◽

Vertical Axis ◽

Wind Turbine Blades ◽

Static Pressure Distribution ◽

Numerical Studies ◽

Airfoil Blades ◽

Torque Values ◽

Naca 0012

This is Part-1 of the two-part paper in considering the effect of cambered airfoil blades on self-starting of vertical axis wind turbine. Part 1 reports the numerical studies on self-starting of vertical axis wind turbine with comparative studies involving NACA 0012 and cambered airfoil NACA 4415. Part 2 of the paper deals with numerical studies of NACA 0018 and cambered air foil NACA 63415. Darrieus type VAWT is attracting many researchers attention for its inherent advantages and its diversified applications. However, a disadvantage is when the rotor is stationary, no net rotational forces arises, even at high-wind speed. The principal advantage of the vertical axis format is their ability to accept wind from any direction without yawing mechanism. However, self-starting capability is the major drawbacks. Moreover, literatures based on computational analysis involving the cambered airfoil are few only. The objective of this present study is to select the suitable airfoil blades on self-starting of VAWT at low-Reynolds number. The numerical studies are carried out to identify self-starting capability of the airfoil using CFD analysis by studying the flow field over the vertical axis wind turbine blades. The commercial CFD code, ANSYS CFX 13.0© was used for the present studies. Initially, the flow over NACA 0012 was simulated and analyzed for different angles of attacks and similarly carried out for NACA 4415. The contours of static pressure distribution and velocity as well as the force and torque were obtained. Even though the lift force for cambered airfoil NACA 4415 is higher, based on the torque values of the above blade profiles, asymmetrical airfoil NACA 0012 is found to be appropriate for self-starring of VAWT.

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference: Volume 1, Symposia – Parts A, B, C, and D ◽

Aerodynamic Analysis for Camber Effect in Vertical Wind Turbine System

10.1115/ajk2011-07010 ◽

2011 ◽

Cited By ~ 1

Author(s):

Jinwook Kim ◽

Dohyung Lee ◽

Junhee Han ◽

Sangwoo Kim

Keyword(s):

Numerical Simulation ◽

Wind Turbine ◽

Vertical Axis ◽

Horizontal Axis Wind Turbine ◽

Low Wind Speed ◽

Wind Turbine System ◽

Physical Features ◽

The Ideal

The Vertical Axis Wind Turbine (VAWT) has advantages over Horizontal Axis Wind Turbine (HAWT) that it allows less chance to be degraded independent of wind direction and turbine can be operated even at the low wind speed. The objective of this study is to analyze aerodynamics of the VAWT airfoil and investigate the ideal shape of airfoil, more specifically cambers. The analysis of aerodynamic characteristics with various cambers has been performed using numerical simulation with CFD software. As the numerical simulation discloses local physical features around wind turbine, aerodynamic performance such as lift, drag and torque are computed for single airfoil rotation and multiple airfoil rotation cases. Through this study more effective airfoil shape is suggested based vortex-airfoil interaction studies.

Numerical Studies on the Effect of Cambered Airfoil Blades on Self-Starting of Vertical Axis Wind Turbine Part 2: NACA 0018 and NACA 63415

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.787.245 ◽

2015 ◽

Vol 787 ◽

pp. 245-249 ◽

Cited By ~ 1

Author(s):

Sivamani Seralathan ◽

T. Micha Premkumar ◽

S. Thangavel ◽

G.P. Pradeep

Keyword(s):

Flow Field ◽

Wind Turbine ◽

Lift Force ◽

Turbine Blades ◽

Vertical Axis ◽

Numerical Studies ◽

Airfoil Blades ◽

Torque Values ◽

Naca 0012

NACA 0012 and NACA 4415 were discussed in Part 1 of the paper to study the capabilities of the airfoil blades by considering the effect of cambered airfoil blade on self-starting of vertical axis wind turbine. The numerical studies are carried out to identify self-starting capability of the airfoil using CFD analysis by studying the flow field over the vertical axis wind turbine blades. In this Part 2 paper, detailed numerical results of asymmetrical NACA 0018 and cambered airfoil NACA 63415 are presented. The lift force generated and the rotor torque induced varies with angle of attack. Based on the contours of static pressure and velocity distribution as well as based on the torque induced in the flow field over blade profiles, NACA 0018 is found to be better compared to cambered airfoil. Even though the lift force for cambered airfoils are higher, based on the rotor torque values, the wind turbine with asymmetrical airfoil blades NACA 0012 is better by 9.80% compared with NACA 4415 and 21.73% compared with NACA 63415. Self-starting issue can be addressed by proper selection of NACA blade profiles. By comparing the four airfoil blades in Part 1 and Part 2 of the papers, the asymmetrical NACA 0012 is found to be most suitable airfoil for self-starting the vertical axis wind turbine (VAWT).

Stress Analysis of Various Shaped Blade of Savonius Wind Turbine

Volume 6B: Energy ◽

10.1115/imece2014-36307 ◽

2014 ◽

Author(s):

Jobaidur R. Khan ◽

Mosfequr Rahman

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Alternative Energy ◽

Energy Requirement ◽

Turbine Blades ◽

Vertical Axis ◽

Physical Models ◽

Low Wind Speed ◽

The World

Amidst of high demand of energy, the world is seeking alternative energy sources. Wind alone can fulfill most of the energy requirement of the world by its efficient conversion into energy. On efficiency measurement, Horizontal Axis Wind Turbines (HAWT) is the popular to the researchers, but it works best in places where the wind is not disturbed and has high wind power. The inherent advantage of facing the wind direction, design simplicity, less expensive technology for construction, lower wind start-up speeds, easier maintenance, and relatively quietness are turning the focus to Vertical Axis Wind Turbine (VAWT). The low wind speed and non-smooth wind flow regions are attracted for these machines. Savonius turbine is the simplest form of VAWT and operation is based on the difference of the drag force on its blades. The main objective of this study is to analyze a perfect mixture of new and innovative designs of Savonius turbine blades, which can make VAWT more attractive, efficient, durable and sustainable. This is studied by using blade with different numbers in operating in different wind speed. A Computational Fluid Dynamics (CFD) analysis has been used. 2D CAD models of various VAWT geometries are created and tested with CFD software ANSYS/FLUENT with a similar flow-driven motion in a wind tunnel. These simulations provided the aero-dynamic characteristics like shear stress, velocity distribution and pressure distribution. Some physical models with desired properties needed to be fabricated and tested inside tunnel to find the effect of different shapes in real.

Improvement of Self-Starting Capabilities of Vertical Axis Wind Turbines with New Design of Turbine Blades

Sustainability ◽

10.3390/su13073854 ◽

2021 ◽

Vol 13 (7) ◽

pp. 3854

Author(s):

Samuel Mitchell ◽

Iheanyichukwu Ogbonna ◽

Konstantin Volkov

Keyword(s):

Wind Turbine ◽

Cfd Simulation ◽

Tangential Force ◽

Turbine Blades ◽

Vertical Axis ◽

Coefficient Of Performance ◽

Small Range ◽

A Minor

A lift-driven vertical axis wind turbine (VAWT) generates peak power when it is rotating at high tip-speed ratios (TSR), at which time the blades encounter angles of attack (AOA) over a small range from zero to 30 degrees. However, its ability to self-start is dependent upon its performance at low TSRs, at which time the blades encounter a range of AOAs from zero to 180 degrees. A novel vented aerofoil is presented with the intention of improving the performance of a lift-driven VAWT at low TSRs without hampering the performance of the wind turbine at high TSRs. Computational fluid dynamics (CFD) simulation is used to predict the aerodynamic characteristics of a new vented aerofoil based on the well documented NACA0012 profile. Simulations are performed using the SST turbulence model. The results obtained show a reduction in the coefficient of tangential force (the force that generates torque on the wind turbine) at low AOAs (less than 90 degrees) of no more than 30%, while at high AOAs (more than 90 degrees) an improvement in the tangential force of over 100% is observed. Using a simple momentum based performance prediction model, these results suggest that this would lead to an increase in torque generation by a theoretical three-bladed VAWT of up to 20% at low TSRs and a minor reduction in coefficient of performance of up to 9% at TSR of 2 and closer to 1% at higher TSRs.

THE EFFECT OF DARRIEUS AND SAVONIUS WIND TURBINES POSITION ON THE PERFORMANCE OF THE HYBRID WIND TURBINE AT LOW WIND SPEED

10.31224/osf.io/grbmv ◽

2020 ◽

Author(s):

Nawfal M. Ali ◽

Abdul Hassan A. K ◽

Sattar Aljabair

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Wind Velocity ◽

Vertical Axis ◽

The Other ◽

Low Wind Speed ◽

Turbine Model ◽

Better Than

This paper presents an experimental and numerical simulation to investigate a hybrid vertical axis wind turbine model highly efficient which can be worked at low wind speed by studying the aerodynamic characteristics of four models of hybrid VAWTs. The hybrid WT consists of the SWT having two blades and the DWT type straight having two blades. Four models were constructed to study experimentally and numerically to choose the best model. Two models were DWT in the upper and SWT in the lower, also two models were SWT in the upper and DWT in the lower. The phase stage angle between the turbines is 0o and 90o . The experimental and numerical results showed that the performance of hybrid WT where DWT in the upper and SWT in the lower with phase stage 90o is better than in the other models, it can be started to work at a wind velocity of 2.2 m/s. At the wind velocity 3 m/s, the values of the parameters are the rotational speed (198 rpm), the CP (0.3195), the CT (0.2003), the TSR (1.6) and self-starting rotation at this value of wind velocity (3 m/s). The efficiency of extracting the wind power by hybrid WT is (51.2 %).