Savonius Wind Turbine Blade Profile Optimization by Coupling CFD Simulations With Simplex Search Technique

2019 ◽  
Author(s):  
Ankit Agrawal ◽  
Divyeshkumar D. Kansagara ◽  
Deepak Sharma ◽  
Ujjwal K. Saha
Keyword(s):  
Wind Turbine ◽  
Rotor Blade ◽  
Optimization Technique ◽  
Low Noise ◽  
Blade Profile ◽  
Search Technique ◽  
Cfd Simulations ◽  
Simplex Search ◽  
Wide Range ◽  
Cubic Spline Curve

Abstract The Savonius rotor, a drag-based vertical axis wind turbine, is characterized by its design simplicity, low noise level, self-starting ability at low wind speed and low cost. However, its low performance is always a major issue. One of the remedies of this issue is to design an optimized rotor blade profile, which has mostly been developed through trial and error approach in the literature. In this paper, an optimum blade profile is obtained by maximizing its power coefficient (CP) by coupling CFD simulations of a rotor blade profile with the simplex search technique. Since the blade profile is symmetric about its axis, half of the blade geometry is created through natural cubic spline curve using three points. Two of them are kept fixed, whereas the other one is changed through optimization technique in its every iteration using MATLAB platform. In every iteration, the blade profile is meshed using ANSYS ICEM CFD. The analysis of the blade profile is performed through ANSYS Fluent by using shear-stress transport k-ω turbulence model. A finite volume method based solver is used to solve the transient 2D flow around the wind turbine. The optimum profile of the blade is compared with the conventional profile over a wide range of tip speed ratios (TSRs) in order to check its feasibility for practical applications. The optimum blade profile is found to be better than the semicircular blade in the range of TSR = 0.6–1.

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 Determination of the Angle of Attack on a Research Wind Turbine Rotor Blade Using Surface Pressure Measurements

2020 ◽  
Author(s):  
Rodrigo Soto-Valle ◽  
Sirko Bartholomay ◽  
Joerg Alber ◽  
Marinos Manolesos ◽  
Christian Navid Nayeri ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Rotor Blade ◽  
Angle Of Attack ◽  
Leading Edge ◽  
Turbine Rotor ◽  
Speed Ratio ◽  
Horizontal Axis Wind Turbine ◽  
Turbine Rotor Blade ◽  
Wide Range ◽  
Wind Turbine Rotor

Abstract. In this paper, a method to determine the angle of attack on a wind turbine rotor blade using a chordwise pressure distribution measurement was applied. The approach uses a reduced number of pressure taps data located close to the blade leading edge. The results were compared with three 3-hole probes located at different radial positions and analytical calculations. The experimental approaches are based on the 2-D flow assumption; the pressure tap method is an application of the thin airfoil theory and the 3-hole probe method uses external probe measurements and applies geometrical and induction corrections. The experiments were conducted in the wind tunnel at the Hermann Föttinger Institut of the Technische Unversität Berlin. The research turbine is a three-bladed upwind horizontal axis wind turbine model with a rotor diameter of 3 m. The measurements were carried out at rated condition with a tip speed ratio of 4.35 and different yaw and pitch angles were tested in order to compare both methods over a wide range of conditions. Results show that the pressure taps method is suitable with a similar angle of attack results as the 3-hole probes for the aligned case. When a yaw misalignment was introduced the method captures the same trend and feature of the analytical estimations. Nevertheless, it is not able to capture the tower influence. Regarding the influence of pitching the blades, a linear relationship between the angle of attack and pitch angle was found.

scholarly journals Determination of the angle of attack on a research wind turbine rotor blade using surface pressure measurements

2020 ◽  
Vol 5 (4) ◽  
pp. 1771-1792
Author(s):  
Rodrigo Soto-Valle ◽  
Sirko Bartholomay ◽  
Jörg Alber ◽  
Marinos Manolesos ◽  
Christian Navid Nayeri ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Rotor Blade ◽  
Angle Of Attack ◽  
Turbine Rotor ◽  
Speed Ratio ◽  
Horizontal Axis Wind Turbine ◽  
Turbine Rotor Blade ◽  
Wide Range ◽  
Wind Turbine Rotor

Abstract. In this paper, a method to determine the angle of attack on a wind turbine rotor blade using a chordwise pressure distribution measurement was applied. The approach used a reduced number of pressure tap data located close to the blade leading edge. The results were compared with the measurements from three external probes mounted on the blade at different radial positions and with analytical calculations. Both experimental approaches used in this study are based on the 2-D flow assumption; the pressure tap method is an application of the thin airfoil theory, while the probe method applies geometrical and induction corrections to the measurement data. The experiments were conducted in the wind tunnel at the Hermann Föttinger Institut of the Technische Universität Berlin. The research turbine is a three-bladed upwind horizontal axis wind turbine model with a rotor diameter of 3 m. The measurements were carried out at rated conditions with a tip speed ratio of 4.35, and different yaw and pitch angles were tested in order to compare the approaches over a wide range of conditions. Results show that the pressure tap method is suitable and provides a similar angle of attack to the external probe measurements as well as the analytical calculations. This is a significant step for the experimental determination of the local angle of attack, as it eliminates the need for external probes, which affect the flow over the blade and require additional calibration.

Performance enhancement of Savonius wind turbine by blade shape and twisted angle modifications

2021 ◽  
pp. 095765092098794
Author(s):  
Ahmed M Nagib Elmekawy ◽  
Hassan A Hassan Saeed ◽  
Sadek Z Kassab
Keyword(s):  
Wind Turbine ◽  
Performance Enhancement ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Vertical Axis ◽  
Cfd Simulations ◽  
Sliding Mesh ◽  
Blade Shape ◽  
Rotor Shape ◽  
Twisting Angle

Three-dimensional CFD simulations are carried out to study the increase of power generated from Savonius vertical axis wind turbines by modifying the blade shape and blade angel of twist. Twisting angle of the classical blade are varied and several proposed novel blade shapes are introduced to enhance the performance of the wind turbine. CFD simulations have been performed using sliding mesh technique of ANSYS software. Four turbulence models; realizable k -[Formula: see text], standard k - [Formula: see text], SST transition and SST k -[Formula: see text] are utilized in the simulations. The blade twisting angle has been modified for the proposed dimensions and wind speed. The introduced novel blade increased the power generated compared to the classical shapes. The two proposed novel blades achieved better power coefficients. One of the proposed models achieved an increase of 31% and the other one achieved 32.2% when compared to the classical rotor shape. The optimum twist angel for the two proposed models achieved 5.66% and 5.69% when compared with zero angle of twist.

scholarly journals Research on Zero-Voltage Ride Through Control Strategy of Doubly Fed Wind Turbine

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2287
Author(s):  
Kaina Qin ◽  
Shanshan Wang ◽  
Zhongjian Kang
Keyword(s):  
Wind Turbine ◽  
Wind Power ◽  
Control Strategy ◽  
Large Scale ◽  
Sliding Mode ◽  
Stable Operation ◽  
Wide Range ◽  
Dc Bus ◽  
Doubly Fed ◽  
Zero Voltage

With the rapid increase in the proportion of the installed wind power capacity in the total grid capacity, the state has put forward higher and higher requirements for wind power integration into the grid, among which the most difficult requirement is the zero-voltage ride through (ZVRT) capability of the wind turbine. When the voltage drops deeply, a series of transient processes, such as serious overvoltage, overcurrent, or speed rise, will occur in the motor, which will seriously endanger the safe operation of the wind turbine itself and its control system, and cause large-scale off-grid accident of wind generator. Therefore, it is of great significance to improve the uninterrupted operation ability of the wind turbine. Doubly fed induction generator (DFIG) can achieve the best wind energy tracking control in a wide range of wind speed and has the advantage of flexible power regulation. It is widely used at present, but it is sensitive to the grid voltage. In the current study, the DFIG is taken as the research object. The transient process of the DFIG during a fault is analyzed in detail. The mechanism of the rotor overcurrent and DC bus overvoltage of the DFIG during fault is studied. Additionally, the simulation model is built in DIgSILENT. The active crowbar hardware protection circuit is put into the rotor side of the wind turbine, and the extended state observer and terminal sliding mode control are added to the grid side converter control. Through the cooperative control technology, the rotor overcurrent and DC bus overvoltage can be suppressed to realize the zero-voltage ride-through of the doubly fed wind turbine, and ensure the safe and stable operation of the wind farm. Finally, the simulation results are presented to verify the theoretical analysis and the proposed control strategy.

An Accelerated Sequential Simplex Search Technique

1973 ◽  
Vol 5 (2) ◽  
pp. 127-134 ◽  
Author(s):  
William E. Biles
Keyword(s):  
Search Technique ◽  
Simplex Search

LOW-NOISE SILICON-ON-INSULATOR HALL DEVICES

2004 ◽  
Vol 04 (02) ◽  
pp. L345-L354 ◽  
Author(s):  
Y. HADDAB ◽  
V. MOSSER ◽  
M. LYSOWEC ◽  
J. SUSKI ◽  
L. DEMEUS ◽  
...  
Keyword(s):  
Noise Level ◽  
Low Voltage ◽  
Silicon Layer ◽  
Electrical Current ◽  
Low Noise ◽  
Silicon On Insulator ◽  
Technological Parameters ◽  
Wide Range ◽  
Hall Sensors ◽  
Soi Technology

Hall sensors are used in a very wide range of applications. A very demanding one is electrical current measurement for metering purposes. In addition to high precision and stability, a sufficiently low noise level is required. Cost reduction through sensor integration with low-voltage/low-power electronics is also desirable. The purpose of this work is to investigate the possible use of SOI (Silicon On Insulator) technology for this integration. We have fabricated SOI Hall devices exploring the useful range of silicon layer thickness and doping level. We show that noise is influenced by the presence of LOCOS and p-n depletion zones near the edges of the active zones of the devices. A proper choice of SOI technological parameters and process flow leads to up to 18 dB reduction in Hall sensor noise level. This result can be extended to many categories of devices fabricated using SOI technology.

Effects of Multiple Impacts and Size Distribution of Particles on Erosion Predictions Using CFD

2007 ◽  
Author(s):  
Yongli Zhang ◽  
Brenton S. McLaury ◽  
Siamack A. Shirzai
Keyword(s):  
Experimental Data ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Target Material ◽  
Average Particle ◽  
Multiple Impacts ◽  
Cfd Simulations ◽  
Erosion Damage ◽  
Wide Range

Erosion equations are usually obtained from experiments by impacting solid particles entrained in a gas or liquid on a target material. The erosion equations are utilized in CFD (Computational Fluid Dynamics) models to predict erosion damage caused by solid particle impingements. Many erosion equations are provided in terms of an erosion ratio. By definition, the erosion ratio is the mass loss of target material divided by the mass of impacting particles. The mass of impacting particles is the summation of (particle mass × number of impacts) of each particle. In erosion experiments conducted to determine erosion equations, some particles may impact the target wall many times and some other particles may not impact the target at all. Therefore, the experimental data may not reflect the actual erosion ratio because the mass of the sand that is used to run the experiments is assumed to be the mass of the impacting particles. CFD and particle trajectory simulations are applied in the present work to study effects of multiple impacts on developing erosion ratio equations. The erosion equation as well as the CFD-based erosion modeling procedure is validated against a variety of experimental data. The results show that the effect of multiple impacts is negligible in air cases. In water cases, however, this effect needs to be accounted for especially for small particles. This makes it impractical to develop erosion ratio equations from experimental data obtained for tests with sand in water or dense gases. Many factors affecting erosion damage are accounted for in various erosion equations. In addition to some well-studied parameters such as particle impacting speed and impacting angle, particle size also plays a significant role in the erosion process. An average particle size is usually used in analyzing experimental data or estimating erosion damage cases of practical interest. In petroleum production applications, however, the size of sand particles that are entrained in produced fluids can vary over a fairly broad range. CFD simulations are also performed to study the effect of particle size distribution. In CFD simulations, particle sizes are normally distributed with the mean equaling the average size of interest and the standard deviation varying over a wide range. Based on CFD simulations, an equation is developed and can be applied to account for the effect of the particle size distribution on erosion prediction for gases and liquids.

Sign in / Sign up

Export Citation Format

Share Document