Theoretical Analysis of the Bladeless Wind Turbine Performance

A bladeless wind turbine utilizes vortex formation to extract energy from the wind. Vortex formation are small swirls of air which occur as a result of the geometric shape of the device. This study designed a bladeless wind turbine which incorporates a structural support at a distance offset from the center axis of the cylindrical mast. Springs were added to the final design as means to provide the stiffness required to obtain resonance with the vortex shedding frequency and to also assist in supporting the structure. The analysis was conducted at wind speeds 1m/s, 4m/s and 7m/s, where the geometrical properties of the device remained constant. MATLAB was used to analyze the equation of motion derived for the device. The variables of interest in the studies were mainly the angular acceleration, power coefficient and the resonant frequency. The results obtained showed that for wind speeds above and below the designed wind speed of 4m/s the angular velocity remained the same. Results of this model showed that high amplitudes occur only at resonance. Results showed that with the current power generating mechanism, the average efficiency attainable is approximately 2% at steady state. This is the theoretical efficiency which could be achieved based on the current model. It was discovered that for linearly tapered cylinders, increased oscillations occurred during the ‘lock-in range’ for a range of reduced velocities. The reduced velocity of the designed wind speed is approximately Vr = 5m/s. This value lies within the theoretical range lock in range where increased oscillations are expected to occur between reduced velocities of 4.75m/s and 8m/s [1].

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Comparison of Various Blade Profiles in a Two-Blade Conventional Savonius Wind Turbine

Journal of Energy Resources Technology ◽

10.1115/1.4047757 ◽

2020 ◽

Vol 143 (2) ◽

Author(s):

Rahim Hassanzadeh ◽

Milad Mohammadnejad ◽

Sajad Mostafavi

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Power Output ◽

Urban Areas ◽

Cost Effective ◽

Maximum Power ◽

Power Coefficient ◽

Total Power ◽

Wind Speeds ◽

Savonius Wind Turbine

Abstract Savonius turbines are one of the old and cost-effective turbines which extract the wind energy by the drag force. Nowadays, they use in urban areas to generate electricity due to their simple structure, ease of maintenance, and acceptable power output under a low wind speed. However, their efficiency is low and the improvement of their performance is necessary to increase the total power output. This paper compares four various blade profiles in a two-blade conventional Savonius wind turbine. The ratios of blade diameter to the blade depth of s/d = 0.3, 0.5, 0.7, and 1 are tested under different free-wind speeds of 3, 5, and 7 m/s and tip speed ratios (TSRs) in the range from 0.2 to 1.2. It is found that the profile of blades in a Savonius rotor plays a considerable role in power characteristics. Also, regardless of blades profile and free-wind speed, the maximum power coefficient develops in TSR = 0.8. In addition, increasing the free-wind speed enhances the rotor performance of all cases under consideration. Finally, it is revealed that the rotor with s/d = 0.5 provides maximum power coefficients in all free-wind speeds and TSR values among the rotors under consideration, whereas the rotor with s/d = 1 is the worth cases.

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Evaluation of the Effect of Blades Number on the Performance of Pico Wind Turbines

Iraqi Journal of Industrial Research ◽

10.53523/ijoirvol8i1id20 ◽

2021 ◽

Vol 8 (1) ◽

pp. 29-39

Author(s):

Yasir Abood ◽

Tariq A. Ismail ◽

Omar A. Abdulrazzaq ◽

Haider S. Hussein

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Wind Turbines ◽

Electrical Power ◽

Internal Resistance ◽

Power Coefficient ◽

Sharp Reduction ◽

Wind Speeds ◽

Air Blower

In this paper, the influence of blades number on the performance of pico wind turbine was investigated by using a small-motorized axial DC fan with a rated power of 4W. Fixed streaming air blower was used as a source of wind. Varying in wind speed was accomplished by changing the distance from the blower. A resistor equals to the turbine internal resistance was utilized as a load to collect the electrical power across the load at various wind speeds and for fans of different blades (1, 2, and 5). Values of the cut-in and cut-out speeds were extracted from the power plot. Rated power was recorded, as well. The results have shown that the rated power generated by turbine has decreased due to the reduction of blades number (i.e., reduction in solidity) from 2.6W for a 5-bladed turbine to 0.665W for a 2-bladed turbine and to 0.13W for a 1-bladed turbine. Moreover, the cut-in speed (initial electrical generating speed) has increased from 4.9m/s for 5-bladed to 8m/s for 2-bladed, then to 19.15m/s for 1-bladed. These results are explained by the balancing problems during rotation (polar asymmetrical rotor), and it is seen that the reduction of blades has made a sharp reduction in power coefficient.

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PENGARUH KECEPATAN ANGIN DAN VARIASI JUMLAH SUDU TERHADAP UNJUK KERJA TURBIN ANGIN POROS HORIZONTAL

Dinamika Teknik Mesin ◽

10.29303/d.v3i1.88 ◽

2013 ◽

Vol 3 (1) ◽

Author(s):

Firman Aryanto ◽

Made Mara ◽

Made Nuarsa

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Mechanical Energy ◽

Performance Testing ◽

Horizontal Axis ◽

Power Coefficient ◽

Speed Ratio ◽

Maximum Speed ◽

Horizontal Axis Wind Turbine ◽

Wind Speeds

The wind turbine is a device that converts wind energy into mechanical energy and then converted into electrical energy through a generator. Horizontal axis wind turbines can increase the efficiency to get the maximum power coefficient. One was using the blade numerous. Maximum efisiensi system will increase the number of watts (power) generated so as to obtain a certain number of watts by simply using the number of windmills lessThe object of this research is the performance testing horizontal axis wind turbine with wind speed variation and variation in terms of the number of blade Efisiensi system (𝜂 ) and Tip Speed Ratio (TSR). Research conducted with the wind coming from the source to the Wind Tunnel fan to direct wind. Wind speed is used there are three variations of the 3 m/s, 3.5 m/s, and 4 m/s and varying the amount of blade that is 3, 4, 5 and 6 blade.The results showed that the best 𝜂 values obtained at a maximum wind speed of 4 m / s and the number of blade 5 with a value of 3.07% 𝜂, whereas 𝜂 smallest value obtained at wind speeds of 3 m/s and the number of blade 3 that the value of 0.05% 𝜂. For TSR maximum value at a maximum speed of 4 m/s occurred in the number of blade 5 is equal to λ = 2.11, while the lowest value at wind speeds of 3 m/s resulting in blade number 3 is equal to λ = 1.49.

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SHAPING OF AN AUTONOMOUS POWER SYSTEM FOR GUARANTEED POWER SUPPLY WITH THE PREDOMINANCE WIND ENERGY

Alternative Energy and Ecology (ISJAEE) ◽

10.15518/isjaee.2018.22-24.028-050 ◽

2018 ◽

pp. 28-50

Author(s):

S. G. Ignatiev ◽

S. V. Kiseleva

Keyword(s):

Energy Storage ◽

Wind Speed ◽

Wind Energy ◽

Wind Turbine ◽

Wind Turbines ◽

Energy Demand ◽

Diesel Generator ◽

Average Wind Speed ◽

Wind Speeds ◽

Average Wind

Optimization of the autonomous wind-diesel plants composition and of their power for guaranteed energy supply, despite the long history of research, the diversity of approaches and methods, is an urgent problem. In this paper, a detailed analysis of the wind energy characteristics is proposed to shape an autonomous power system for a guaranteed power supply with predominance wind energy. The analysis was carried out on the basis of wind speed measurements in the south of the European part of Russia during 8 months at different heights with a discreteness of 10 minutes. As a result, we have obtained a sequence of average daily wind speeds and the sequences constructed by arbitrary variations in the distribution of average daily wind speeds in this interval. These sequences have been used to calculate energy balances in systems (wind turbines + diesel generator + consumer with constant and limited daily energy demand) and (wind turbines + diesel generator + consumer with constant and limited daily energy demand + energy storage). In order to maximize the use of wind energy, the wind turbine integrally for the period in question is assumed to produce the required amount of energy. For the generality of consideration, we have introduced the relative values of the required energy, relative energy produced by the wind turbine and the diesel generator and relative storage capacity by normalizing them to the swept area of the wind wheel. The paper shows the effect of the average wind speed over the period on the energy characteristics of the system (wind turbine + diesel generator + consumer). It was found that the wind turbine energy produced, wind turbine energy used by the consumer, fuel consumption, and fuel economy depend (close to cubic dependence) upon the specified average wind speed. It was found that, for the same system with a limited amount of required energy and high average wind speed over the period, the wind turbines with lower generator power and smaller wind wheel radius use wind energy more efficiently than the wind turbines with higher generator power and larger wind wheel radius at less average wind speed. For the system (wind turbine + diesel generator + energy storage + consumer) with increasing average speed for a given amount of energy required, which in general is covered by the energy production of wind turbines for the period, the maximum size capacity of the storage device decreases. With decreasing the energy storage capacity, the influence of the random nature of the change in wind speed decreases, and at some values of the relative capacity, it can be neglected.

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Canard optimization for enhancing the performance of small horizontal axis wind turbine at low wind speeds

Journal of Mechanics ◽

10.1093/jom/ufaa004 ◽

2020 ◽

Vol 37 ◽

pp. 63-71

Author(s):

Yui-Chuin Shiah ◽

Chia Hsiang Chang ◽

Yu-Jen Chen ◽

Ankam Vinod Kumar Reddy

Keyword(s):

Wind Turbine ◽

Urban Areas ◽

Horizontal Axis ◽

Power Coefficient ◽

Peak Performance ◽

Small Scale ◽

Horizontal Axis Wind Turbine ◽

Wind Speeds ◽

Optimum Parameters ◽

Low Wind Speeds

ABSTRACT Generally, the environmental wind speeds in urban areas are relatively low due to clustered buildings. At low wind speeds, an aerodynamic stall occurs near the blade roots of a horizontal axis wind turbine (HAWT), leading to decay of the power coefficient. The research targets to design canards with optimal parameters for a small-scale HAWT system operated at variable rotational speeds. The design was to enhance the performance by delaying the aerodynamic stall near blade roots of the HAWT to be operated at low wind speeds. For the optimal design of canards, flow fields of the sample blades with and without canards were both simulated and compared with the experimental data. With the verification of our simulations, Taguchi analyses were performed to seek the optimum parameters of canards. This study revealed that the peak performance of the optimized canard system operated at 540 rpm might be improved by ∼35%.

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Experimental Study of Vertical Axis Wind Turbine with Wind Speed Self-Adapting

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.215-216.1323 ◽

2012 ◽

Vol 215-216 ◽

pp. 1323-1326

Author(s):

Ming Wei Xu ◽

Jian Jun Qu ◽

Han Zhang

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Wind Velocity ◽

Vertical Axis ◽

Maximum Power ◽

The Self ◽

Power Coefficient ◽

Speed Ratio ◽

Vertical Axis Wind Turbine ◽

Opening And Closing

A small vertical axis wind turbine with wind speed self-adapting was designed. The diameter and height of the turbine were both 0.7m. It featured that the blades were composed of movable and fixed blades, and the opening and closing of the movable blades realized the wind speed self-adapting. Aerodynamic performance of this new kind turbine was tested in a simple wind tunnel. Then the self-starting and power coefficient of the turbine were studied. The turbine with load could reliably self-start and operate stably even when the wind velocity was only 3.6 m/s. When the wind velocity was 8 m/s and the load torque was 0.1Nm, the movable blades no longer opened and the wind turbine realized the conversion from drag mode to lift mode. With the increase of wind speed, the maximum power coefficient of the turbine also improves gradually. Under 8 m/s wind speed, the maximum power coefficient of the turbine reaches to 12.26%. The experimental results showed that the new turbine not only improved the self-starting ability of the lift-style turbine, but also had a higher power coefficient in low tip speed ratio.

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Numerical Simulation of the Aeroelastic Response of Wind Turbines in Typhoons Based on the Mesoscale WRF Model

Sustainability ◽

10.3390/su12010034 ◽

2019 ◽

Vol 12 (1) ◽

pp. 34

Author(s):

Long Wang ◽

Cheng Chen ◽

Tongguang Wang ◽

Weibin Wang

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Wind Direction ◽

Flow Direction ◽

Wrf Model ◽

Normal Operation ◽

Average Wind Speed ◽

Aeroelastic Response ◽

Response Characteristics ◽

Wind Speeds

A new simulation method for the aeroelastic response of wind turbines under typhoons is proposed. The mesoscale Weather Research and Forecasting (WRF) model was used to simulate a typhoon’s average wind speed field. The measured power spectrum and inverse Fourier transform method were coupled to simulate the pulsating wind speed field. Based on the modal method and beam theory, the wind turbine model was constructed, and the GH-BLADED commercial software package was used to calculate the aerodynamic load and aeroelastic response. The proposed method was applied to assess aeroelastic response characteristics of a commercial 6 MW offshore wind turbine under different wind speeds and direction variation patterns for the case study of typhoon Hagupit (2008), with a maximal wind speed of 230 km/h. The simulation results show that the typhoon’s average wind speed field and turbulence characteristics simulated by the proposed method are in good agreement with the measured values: Their difference in the main flow direction is only 1.7%. The scope of the wind turbine blade in the typhoon is significantly larger than under normal wind, while that under normal operation is higher than that under shutdown, even at low wind speeds. In addition, an abrupt change in wind direction has a significant impact on wind turbine response characteristics. Under normal operation, a sharp variation of the wind direction by 90 degrees in 6 s increases the wind turbine (WT) vibration scope by 27.9% in comparison with the case of permanent wind direction. In particular, the maximum deflection of the wind tower tip in the incoming flow direction reaches 28.4 m, which significantly exceeds the design standard safety threshold.

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Investigation of an Innovative Rotor Modification for a Small-Scale Horizontal Axis Wind Turbine

Energies ◽

10.3390/en13102649 ◽

2020 ◽

Vol 13 (10) ◽

pp. 2649 ◽

Cited By ~ 1

Author(s):

Artur Bugała ◽

Olga Roszyk

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Cfd Simulation ◽

Turbine Blades ◽

Three Dimensional ◽

Horizontal Axis ◽

Power Coefficient ◽

Small Scale ◽

Horizontal Axis Wind Turbine ◽

Airflow Distribution

This paper presents the results of the computational fluid dynamics (CFD) simulation of the airflow for a 300 W horizontal axis wind turbine, using additional structural elements which modify the original shape of the rotor in the form of multi-shaped bowls which change the airflow distribution. A three-dimensional CAD model of the tested wind turbine was presented, with three variants subjected to simulation: a basic wind turbine without the element that modifies the airflow distribution, a turbine with a plano-convex bowl, and a turbine with a centrally convex bowl, with the hyperbolic disappearance of convexity as the radius of the rotor increases. The momentary value of wind speed, recorded at measuring points located in the plane of wind turbine blades, demonstrated an increase when compared to the base model by 35% for the wind turbine with the plano-convex bowl, for the wind speed of 5 m/s, and 31.3% and 49% for the higher approaching wind speed, for the plano-convex bowl and centrally convex bowl, respectively. The centrally convex bowl seems to be more appropriate for higher approaching wind speeds. An increase in wind turbine efficiency, described by the power coefficient, for solutions with aerodynamic bowls was observed.

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Analysis of the Patent of a Protective Cover for Vertical-Axis Wind Turbines (VAWTs): Simulations of Wind Flow

Sustainability ◽

10.3390/su12187818 ◽

2020 ◽

Vol 12 (18) ◽

pp. 7818

Author(s):

Jose Alberto Moleón Baca ◽

Antonio Jesús Expósito González ◽

Candido Gutiérrez Montes

Keyword(s):

Wind Speed ◽

Wind Turbine ◽

Wind Turbines ◽

High Speed ◽

Experimental Tests ◽

Weather Conditions ◽

Vertical Axis ◽

Good Alternative ◽

Wind Speeds ◽

Vertical Axis Wind Turbines

This paper presents a numerical and experimental analysis of the patent of a device to be used in vertical-axis wind turbines (VAWTs) under extreme wind conditions. The device consists of two hemispheres interconnected by a set of conveniently implemented variable section ducts through which the wind circulates to the blades. Furthermore, the design of the cross-section of the ducts allows the control of the wind speed inside the device. These ducts are intended to work as diffusers or nozzles, depending on the needs of the installation site. Simulations were performed for the case of high-speed external wind, for which the ducts act as diffusers to reduce wind speed and maintain a well-functioning internal turbine. Four different patent designs were analyzed, focusing on turbine performance and generated power. The results indicate that the patent allows the generation of electric power for a greater range of wind speeds than with a normal wind turbine. The results support that this patent may be a good alternative for wind power generation in geographic areas with extreme weather conditions or with maintained or strong gusty wind. Experimental tests were carried out on the movement of the blades using the available model. Finally, the power curve of the model of this wind turbine was obtained.

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Study on the Influence of Baseline Control System on the Fragility of Large-Scale Wind Turbine considering Seismic-Aerodynamic Combination

Advances in Civil Engineering ◽

10.1155/2020/8471761 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Chenyang Yuan ◽

Jing Li ◽

Jianyun Chen ◽

Qiang Xu ◽

Yunfei Xie

Keyword(s):

Control System ◽

Wind Speed ◽

Wind Turbine ◽

Large Scale ◽

Fragility Curves ◽

Operating Conditions ◽

Ground Acceleration ◽

Wind Speeds ◽

Speed Range ◽

Wind Actions

The purpose of this paper is to explore the effect of the baseline control system (BCS) on the fragility of large-scale wind turbine when seismic and wind actions are considered simultaneously. The BCS is used to control the power output by regulating rotor speed and blade-pitch angle in real time. In this study, the fragility analysis was performed and compared between two models using different peak ground acceleration, wind speeds, and specified critical levels. The fragility curves with different wind conditions are obtained using the multiple stripe analysis (MSA) method. The calculation results show that the probability of exceedance specified critical level increases as the wind speed increases in model 1 without considering BCS, while does not have an obvious change in the below-rated wind speed range and has a significant decrease in the above-rated wind speed range in model 2 with considering BCS. The comparison depicts that if the BCS is neglected, the fragility of large-scale wind turbine will be underestimated in around the cut-in wind speed range and overestimated in the over-rated wind speed range. It is concluded that the BCS has a great effect on the fragility especially within the operating conditions when the rated wind speed is exceeded, and it should be considered when estimating the fragility of wind turbine subjected to the interaction of seismic and aerodynamic loads.

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