scholarly journals New Blade Profile of VAWT: Experimental and Analysis to Introduce It in Urban Cites

2021 ◽  
Vol 16 (1) ◽  
pp. 69-76
Author(s):  
Aouachria Zeroual ◽  
Belalmi Rabab ◽  
Haddad Louiza ◽  
Tighaza Sihem
Keyword(s):  
Direct Measurement ◽  
Wind Turbines ◽  
Pressure Field ◽  
Small Scale ◽  
Blade Profile ◽  
Original Experiment ◽  
Generalized Model ◽  
Savonius Rotor ◽  
Experiment Analysis

The use of wind turbines for small-scale and urban applications is a topic that is receiving increasing attention. The use of wind turbines for small-scale and urban applications is a topic that is receiving increasing attention. This work concerns the Savonius rotor. It is divided into three parts. The first one consists in an original experiment which has led to the direct measurement of the pressure field on the blades of a rotating Savonius rotor. In the second part, the results are introduced in a generalized model to calculate the efforts which generate the vibrations at the rotor supports. This study explains well the vibratory behaviour of the rotor. Finally, in a third part an experiment analysis of an adequate system of a suspension to stabilise or avoid these vibrations is proposed. This study explains clearly the vibratory behaviour of the rotor.

scholarly journals Formulation, Validation, and Application of a Novel 3D BEM Tool for Vertical Axis Wind Turbines of General Shape and Size

2021 ◽  
Vol 11 (13) ◽  
pp. 5874
Author(s):  
Andrea G. Sanvito ◽  
Vincenzo Dossena ◽  
Giacomo Persico
Keyword(s):  
Wind Tunnel ◽  
Wind Turbines ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Small Scale ◽  
Engineering Practice ◽  
Blade Profile ◽  
General Shape ◽  
Vertical Axis Wind Turbines ◽  
Shape And Size

Low order models based on the Blade Element Momentum (BEM) theory exhibit modeling issues in the performance prediction of Vertical Axis Wind Turbines (VAWT) compared to Computational Fluid Dynamics, despite the widespread engineering practice of such methods. The present study shows that the capability of BEM codes applied to VAWTs can be greatly improved by implementing a novel three-dimensional set of high-order corrections and demonstrates this by comparing the BEM predictions against wind-tunnel experiments conducted on three small-scale VAWT models featuring different rotor design (H-shaped and Troposkein), blade profile (NACA0021 and DU-06-W200), and Reynolds number (from 0.8×105 to 2.5×105). Though based on the conventional Double Multiple Stream Tube (DMST) model, the here-presented in-house BEM code incorporates several two-dimensional and three-dimensional corrections including: accurate extended polar data, flow curvature, dynamic stall, a spanwise-distributed formulation of the tip losses, a fully 3D approach in the modeling of rotors featuring general shape (such as but not only, the Troposkein one), and accounting for the passive effects of supporting struts and pole. The detailed comparison with experimental data of the same models, tested in the large-scale wind tunnel of the Politecnico di Milano, suggests the very good predictive capability of the code in terms of power exchange, torque coefficient, and loads, on both time-mean and time-resolved basis. The peculiar formulation of the code allows including in a straightforward way the usual spanwise non-uniformity of the incoming wind and the effects of skew, thus allowing predicting the turbine operation in a realistic open-field in presence of the environmental boundary layer. A systematic study on the operation of VAWTs in multiple environments, such as in coastal regions or off-shore, and highlighting the sensitivity of VAWT performance to blade profile selection, rotor shape and size, wind shear, and rotor tilt concludes the paper.

Estimating the Aerodynamic Coefficients of a Savonius Rotor Blade Profile Developed Through the Simplex Search Method

2021 ◽  
Author(s):  
Man Mohan ◽  
Divyeshkumar D. Kansagara ◽  
Deepak Sharma ◽  
Ujjwal K. Saha
Keyword(s):  
Numerical Simulations ◽  
Rotor Blade ◽  
Aerodynamic Drag ◽  
Search Method ◽  
Small Scale ◽  
Blade Profile ◽  
Savonius Rotor ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Cubic Spline Curve

Abstract The Savonius rotor, a type of vertical-axis wind turbine, seems to be promising for small-scale power generation. Most of the studies conducted so far have focused on the evaluation of torque and power coefficients (CT, CP) of the rotor. This paper aims at analyzing the aerodynamic drag and lift coefficients (CD, CL) of a Savonius rotor blade profile that is generated by the simplex search method to maximize its CP. The optimization is carried out by coupling the numerical simulations with the simplex search method. The optimized blade profile thus obtained is symmetric about its axis, where one half is created through a natural cubic spline curve using three points. Two-dimensional (2D) unsteady numerical simulations have been conducted by adopting ANSYS FLUENT solver to examine the CD and CL of the optimized blade profile at an inlet air velocity of 7.30 m/s. The shear stress transport (SST) k-ω turbulence model is used to solve the transient Reynolds-averaged Navier-Stokes (RANS) equations. The aerodynamic analysis is performed over a range of tip speed ratios (TSRs). The total pressure, velocity magnitudes, and the turbulent intensity contours of the optimized blade profile are generated and studied at different angles of rotation. The CD and CL of the blade profile are investigated for a complete rotation with an increment of 1°. At TSR = 0.8, the optimized profile shows a CDmax of 1.91 at an angle of rotation of 54°, while CDmin is found to be 0.45 at an angle 147°.

scholarly journals Optimal Design of Novel Blade Profile for Savonius Wind Turbines

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3484
Author(s):  
Tai-Lin Chang ◽  
Shun-Feng Tsai ◽  
Chun-Lung Chen
Keyword(s):  
Wind Energy ◽  
Drag Force ◽  
Wind Turbines ◽  
Rural Areas ◽  
Large Scale ◽  
Design Method ◽  
Angular Position ◽  
Vertical Axis ◽  
Blade Profile ◽  
Main Concept

Since the affirming of global warming, most wind energy projects have focused on the large-scale Horizontal Axis Wind Turbines (HAWTs). In recent years, the fast-growing wind energy sector and the demand for smarter grids have led to the use of Vertical Axis Wind Turbines (VAWTs) for decentralized energy generation systems, both in urban and remote rural areas. The goals of this study are to improve the Savonius-type VAWT’s efficiency and oscillation. The main concept is to redesign a Novel Blade profile using the Taguchi Robust Design Method and the ANSYS-Fluent simulation package. The convex contour of the blade faces against the wind, creating sufficient lift force and minimizing drag force; the concave contour faces up to the wind, improving or maintaining the drag force. The result is that the Novel Blade improves blade performance by 65% over the Savonius type at the best angular position. In addition, it decreases the oscillation and noise accordingly. This study achieved its two goals.

Arriving at the Optimum Overlap Ratio for an Elliptical-Bladed Savonius Rotor

2017 ◽  
Author(s):  
Nur Alom ◽  
Ujjwal K. Saha
Keyword(s):  
Numerical Study ◽  
Superior Performance ◽  
Navier Stokes ◽  
Speed Ratio ◽  
Small Scale ◽  
Efficient Manner ◽  
Ansys Fluent ◽  
Savonius Rotor ◽  
Velocity Magnitude ◽  
Overlap Ratio

The Savonius rotor appears to be particularly promising for the small-scale applications because of its design simplicity, good starting ability, and insensitivity to wind directions. There has been a growing interest in recent times to harness wind energy in an efficient manner by developing newer blade profiles of Savonius rotor. The overlap ratio (OR), one of the important geometric parameters, plays a crucial role in the turbine performance. In a recent study, an elliptical blade profile with a sectional cut angle (θ) of 47.5° has demonstrated its superior performance when set at an OR = 0.20. However, this value of OR is ideal for a semicircular profile, and therefore, requires further investigation to arrive at the optimum overlap ratio for the elliptical profile. In view of this, the present study attempts to make a systemic numerical study to arrive at the optimum OR of the elliptical profile having sectional cut angle, θ = 47.5°. The 2D unsteady simulation is carried out around the elliptical profile considering various overlap ratios in the range of 0.0 to 0.30. The continuity, unsteady Reynolds Averaged Navier-Stokes (URANS) equations and two equation eddy viscosity SST (Shear Stress transport) k-ω model are solved by using the commercial finite volume method (FVM) based solver ANSYS Fluent. The torque and power coefficients are calculated as a function of tip speed ratio (TSR) and at rotating conditions. The total pressure, velocity magnitude and turbulence intensity contours are obtained and analyzed to arrive at the intended objective. The numerical simulation demonstrates an improved performance of the elliptical profile at an OR = 0.15.

Computer Analysis of S822 Aerofoil Section for Blades of Small Wind Turbines at Low Wind Speed

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Prachi R. Prabhukhot ◽  
Aditya R. Prabhukhot
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Cfd Simulation ◽  
Maximum Velocity ◽  
Small Scale ◽  
Blade Profile ◽  
Ansys Fluent ◽  
Low Wind Speed ◽  
Upward Direction ◽  
Computational Fluid Dynamics Cfd

The power generated in wind turbine depends on wind speed and parameters of blade geometry like aerofoil shape, blade radius, chord length, pitch angle, solidity, etc. Aerofoil selection is the crucial factor in establishing the efficient wind turbine. More than one aerofoil in a blade can increase the efficiency further. Previous studies of different aerofoils have shown that efficiency of small scale wind turbine increases when NREL S822 aerofoil is used for wind speed on and above 10 m/s. This paper introduces a study on effect of low wind speed (V = 5 m/s) on performance of blade profile. Aerofoils NREL S822/S823 are used for microwind turbine with S823 near root and S822 near tip. Blade of 3 m radius with spherical tubercles over entire span is analyzed considering 5 deg angle of attack. The computational fluid dynamics (CFD) simulation was carried out using ANSYS fluent to study the behavior of blade profile at various contours. The study shows that blade experiences maximum turbulence and minimum pressure near trailing edge of the tip of blade. The region also experiences maximum velocity of the flow. These factors result in pushing the aerofoil in upward direction for starting the wind turbine to rotate at the speed as low as 5 m/s.

Detailed Analysis of the Wake Structure of a Straight-Blade H-Darrieus Wind Turbine by Means of Wind Tunnel Experiments and Computational Fluid Dynamics Simulations

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Alessandro Bianchini ◽  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Lorenzo Ferrari ◽  
Giacomo Persico ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Wind Tunnel ◽  
Wind Turbines ◽  
Large Scale ◽  
Vertical Axis ◽  
Performance Estimation ◽  
Small Scale ◽  
Dynamics Simulations

Darrieus vertical axis wind turbines (VAWTs) have been recently identified as the most promising solution for new types of applications, such as small-scale installations in complex terrains or offshore large floating platforms. To improve their efficiencies further and make them competitive with those of conventional horizontal axis wind turbines, a more in depth understanding of the physical phenomena that govern the aerodynamics past a rotating Darrieus turbine is needed. Within this context, computational fluid dynamics (CFD) can play a fundamental role, since it represents the only model able to provide a detailed and comprehensive representation of the flow. Due to the complexity of similar simulations, however, the possibility of having reliable and detailed experimental data to be used as validation test cases is pivotal to tune the numerical tools. In this study, a two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes (U-RANS) computational model was applied to analyze the wake characteristics on the midplane of a small-size H-shaped Darrieus VAWT. The turbine was tested in a large-scale, open-jet wind tunnel, including both performance and wake measurements. Thanks to the availability of such a unique set of experimental data, systematic comparisons between simulations and experiments were carried out for analyzing the structure of the wake and correlating the main macrostructures of the flow to the local aerodynamic features of the airfoils in cycloidal motion. In general, good agreement on the turbine performance estimation was constantly appreciated.

An Analysis and Experimental Study of the Rotor Blade with Composite Material Fiber Reinforced Plastics

2006 ◽  
Vol 306-308 ◽  
pp. 851-856
Author(s):  
C.Y. Son ◽  
H.I. Byun ◽  
K.H. Kim ◽  
J.K. Choi ◽  
J.Y. Shin
Keyword(s):  
Wind Turbines ◽  
Rotor Blade ◽  
Large Scale ◽  
Fem Analysis ◽  
Small Scale ◽  
Fiber Reinforced ◽  
Fatigue Load ◽  
Reinforced Plastics ◽  
Bending Load ◽  
Behavior Characteristic

In these days, large-scale wind turbines are being made of the Glass Fiber Reinforced Plastic (hereinafter F.R.P). Some reinforcement stiffeners such as carbon fiber and polyamide (Kevlar) are not economical for the wind turbine. In addition, the steel or aluminum alloy, featuring heavy weight and metallic fatigue load, is not suitable for global use, except very small-scale wind turbines. In this study, we manufactured a 10kW-grade small Rotor Blade with the F. R. P featuring high stiffness and good dynamic behavior characteristic, and carried out experiments for understanding the bending behavior characteristic of the fatigue load and bending load. And, we examined the experiment results through the Finite Element Method. We compared the experiment results and FEM analysis outputs using the commercial ANSYS FEM program.

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