Small-scale Wind Turbine Research Articles

Systematic investigation of effect of rotor solidity on vertical-axis wind turbines: Power performance and aerodynamics analysis

Small-scale vertical-axis wind turbines (VAWTs) are receiving growing interest for applications in urban areas. However, the unsatisfactory power performance, mainly induced by the complex blade aerodynamics, restricts their development. Optimizing the turbine geometry is expected to improve the blade aerodynamics. In the present study, the effect of rotor solidity on the power performance and aerodynamics of VAWTs is systematically investigated using high-fidelity improved delayed detached-eddy simulations. A wide range of rotor solidity from 0.12 to 0.6 is studied for VAWTs with different numbers of blades, i.e., two- and three-bladed VAWTs. Also, different rotor diameters (0.5 m–2 m), covering VAWTs from domestic to building integration, are compared to explore the scale effect. In addition, the Reynolds number effect induced by the change of turbine geometry is considered and its impact on the solidity effect is elucidated. The results show that a low to moderate rotor solidity (e.g., lower than 0.3) allows the VAWT to achieve appreciable peak power performance. When the inflow velocity is fixed, for a given relatively low rotor solidity (e.g., 0.12), the two-bladed design is expected to achieve higher peak turbine power, while the three-bladed design is more advantageous when the rotor solidity is relatively high (e.g., 0.36). For a given rotor solidity, VAWTs with smaller rotor diameters perform relatively better due to the diminished tip loss effect. The effects of number of blades and rotor diameter are strongly affected by the variation of the chord-based Reynolds number. This study would support the optimal design of urban VAWTs.

NACA2412 airfoil based method for design and aerodynamic analysis of small HAWT using modified BEM approach

Efficient utilization of wind energy depends on careful selection and suitable design of Wind Turbine (WT) blades. Small scale Wind Turbines (SWT) normally operate in the low range of Angle of Attack (AoA). This makes the task even more difficult for designing and optimization of WT blades. This article deals with an airfoil based computational approach to design the blade for a standalone small scale Horizontal Axis Wind Turbine (HAWT). A procedure has been proposed to find the important parameters and analyze the performance characteristics for a three bladed HAWT operating under the wake rotation. Computational code has been written to find optimum blade profile. Twist angle variation, chord length and other related parameters are determined with the help of program. Comparison between different types of airfoil has been made to figure out the most suitable one. Airfoil selection and design approach are intended to make Wind Turbine blade efficient specially under low range of AoA. Characteristics of the Wind Turbine obtained analytically from this procedure are compared with several other reported earlier in some of the literatures. The result obtained by the proposed procedure is simpler and more efficient than BEM theory – a method normally employed for blade design.

Design & development of a Nano Wind Turbine

In this paper, the design & development of a Nano Wind Turbine is presented. Small-scale wind turbines have received less attention compared to their large-scale counterparts, prompting the need for studies in this area. This research focuses on the dynamic properties of "Glass reinforced fiber composite" blades in a nano wind turbine, providing both experimental and analytical results. The study investigates crucial parameters such as the natural frequency and mode shapes of the turbine, which are necessary for determining its performance and lifespan. Additionally, the results are used to set safe blade rotation speeds. Using Creo Parametric software, a detailed ANSYS Workbench 14.0 model is developed for simulation, incorporating the material properties of Glass reinforced fibre composite. The mathematical and experimental results are compared, and the first four modes are found to be within acceptable limits, verifying the dynamic properties of the Glass reinforced fiber composite. The work done & presented in this paper is the result of the mini-project work that has been done by the first sem engineering students of the college and as such there is little novelty in it and the references are being taken from various sources from the internet, the paper is being written by the students to test their writing skills in the starting of their engineering career and also to test the presentation skills during their mini-project presentation. The work done & presented in this paper is the report of the assignment / alternate assessment tool as a part and parcel of the academic assignment of the first year subject on nanotechnology & IoT.

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

Effects of airfoil thickness on the aerodynamic efficiency of a small-scale wind turbine blade

Potential and economic feasibility of a wind power plant in Ciudad Juárez, México

This study investigated the wind energy potential of Ciudad Juárez (Chihuahua, México) for a whole year. The viability of employing three small-scale wind turbine models, including the S-343, Bergey BWC Excel, and AOC 15/50, in Ciudad Juarez, located in the northern Mexican state of Chihuahua in Mexico, is studied in the first stage using RETScreen software. The performance of these three turbine models was subjected to sensitivity analysis in the following study stage using the three defined economic scenarios, assuming a 7% inflation rate, a 9% discount rate, a 7% fuel cost escalation rate, and a 20-year project duration. Finally, the circumstances under which these turbines operate in Ciudad Juarez are discussed economically. Findings indicate that the study site is not economically appropriate, not even for the installation of specific small wind turbines. Finally, it was suggested that the viability of adopting alternative renewable energy systems, such as solar and hybrid systems (photovoltaic wind), be examined in the upcoming study in Ciudad Juárez.

A new similarity criterion and design method for wind tunnel model tests of floating offshore wind turbines

Floating offshore wind turbines (FOWTs) have received strong attention in recent years, and numerous experimental studies have been conducted on them. However, the small-scaled wind turbine models designed by the criterion of traditional thrust coefficient similarity are unable to obtain similar power coefficients with the prototype, and they are not able to reflect the expected dynamic aerodynamics induced by the platform motions. To this end, this paper presents a new criterion for wind tunnel model tests based on the mapping of the optimal tip speed ratio (TSR) and the similarity of the changing rate of the relative TSR. The National Renewable Energy Laboratory's offshore 5-MW wind turbine is selected as the prototype wind turbine. The blade of the model wind turbine is generated by NACA 4412 airfoil, and the chord and twist are optimized by the genetic algorithm. The objective is to keep the thrust and power coefficients of the model wind turbine around the optimal TSR consistent with that of the prototype through a linear mapping relationship. Dynamic simulations with the Unsteady Blade-Element Momentum method are performed to verify the new similarity criterion at different surge frequencies. Compared with those of the model wind turbine designed by the traditional method, fluctuations of the mapped thrust and power coefficients of the new model are in better agreement with the prototype. Hysteresis effects with respect to the relative TSR are newly captured, and loops of the new model are also closer to that of the prototype. This paper provides a more reasonable criterion for wind tunnel model tests of FOWTs, and the dynamic aerodynamics of the prototype can be reflected more accurately compared with the traditional method, which is important for the performance evaluation and optimization design of large-scale FOWTs.

Closed-Form Solution for the Natural Frequencies of Low-Speed Cracked Euler–Bernoulli Rotating Beams

In this study, two closed-form solutions for determining the first two natural frequencies of the flapwise bending vibration of a cracked Euler–Bernoulli beam at low rotational speed have been developed. To solve the governing differential equations of motion, the Frobenius method of solution in power series has been used. The crack has been modeled using two undamaged parts of the beam connected by a rotational spring. From the previous results, two novel polynomial expressions have been developed to obtain the first two natural frequencies as a function of angular velocity, slenderness ratio, cube radius and crack characteristics (depth and location). These expressions have been formulated using multiple regression techniques. To the knowledge of the authors, there is no similar expressions in the literature, which calculate, in a simple way, the first two natural frequencies based on beam features and crack parameters, without the need to know or solve the differential equations of motion governing the beam. In summary, the derived natural frequency expressions provide an extremely simple, practical, and accurate instrument for studying the dynamic behavior of rotating cracked Euler–Bernoulli beams at low angular speed, especially useful, in the future, to establish small-scale wind turbines’ maintenance planes.

New developments in small scale wind turbines

Considering the global socio-economic context, the pressure on natural resources and of course the effects that exploitation has on natural ecosystems and fauna is more and more evident. The use of renewable energy sources, together with improvements in energy efficiency, can help reduce energy consumption, reduce greenhouse gas emissions and, consequently, prevent dangerous climate change. The integration of renewable energy sources in urban areas and in everyday life is a viable solution. The present paper focuses on the presentation of small-scale wind systems integrated in urban areas and not only to capitalize any energy as efficiently as possible.

Installation and Performance Study of a Vertical-Axis Wind Turbine Prototype Model

Amongst various sources of renewable energy, the kinetic energy of blowing wind has environmental friendliness and easy availability, together with other benefits. The wind energy is converted into usable electrical energy by means of a robust device termed a wind turbine. To carry out a performance study of such a device, a small-scale model vertical-axis wind turbine was installed at the laboratory and was run by artificial wind energy produced by a pedestal fan for low and medium speeds and a blower for higher speeds. The variation in critical parameters such as output power and voltage with different speeds was studied. The average output power and voltage were observed to increase with average shaft speed with linear and curvilinear patterns, respectively. The vibration produced at the bearing shaft resulting from the rotating components was analyzed as well. As observed, the peak values of critical vibration parameters such as displacement, velocity, acceleration, and frequency mostly varied curvilinearly with average shaft speeds. To study the applicability of the power generation, an electronically controlled automatic drip irrigation system was allowed to run by the wind turbine and important observations were made. Theoretical analyses (numerical and analytical) of the wind flow and power generation were also performed.

Structural Analysis of Carbon Fiber 3D-Printed Ribs for Small Wind Turbine Blades.

This work provides a structural analysis of small-scale 3D-printed wind turbine ribs subjected to compression. The ribs were manufactured according to NACA 23015 and NACA 633618 geometries, with polylactic acid (PLA) and polylactic acid with carbon fiber additives (CF-PLA). In addition, holes were manufactured into the sample bodies by either 3D printing or drilling for being compared with solid samples. The compression testing was performed by following the ASTM 695D standard, whereas the beginning and propagation of delamination were assessed with the ASTM 5528 standard. Experimental results revealed that 3D-printed built-in holes provided higher compression strength, hence higher structural efficiency, than the drilled samples. Significant improvement by adding carbon fiber additives into the PLA resin system in comparison to raw PLA was detected for at least one of the studied airfoil profiles. NACA geometries also represented a key parameter for avoiding stress concentration areas, as the FEM modeling supported. However, in damaged areas, fracture mechanisms were observed such as bead-bridging, which is a key parameter in reinforcing and consolidating the specimen bodies. Working in better interphase bonding and different additives between beads and layers is highly suggested for future studies.

Effects of blade number on the aerodynamic performance and wake characteristics of a small horizontal-axis wind turbine

Small-scale horizontal-axis wind turbines (SHAWTs) are powerful equipments for wind energy conversion. Furthermore, the wake vortices generated by SHAWTs are used in structural engineering to potentially mitigate vibrations. The blade number of SHAWTs is an important parameter for determining the wake vortices, and thus, in addition to its impact on power generation, it significantly influences structural vibration control. Consequently, the aerodynamic performance and wake characteristics of SHAWTs, with blade numbers from 2 to 5 and tip speed ratio from 1 to 6, were systematically investigated using large-eddy simulations and wind tunnel tests. A superior SHAWT with a high power coefficient (>35 %) was designed. The near-wake characteristics and wake evolution were highly sensitive to blade number. An increased number of rotor blades resulted in a (i) wider near wake, (ii) faster decrease in streamwise vorticity, and (iii) greater velocity deficit (VD) and turbulence intensity (TI) in the near wake. Furthermore, in the far wake, the unstable positions of the tip vortices and peak positions of the TI were closer to the rotor and the VD recovered faster, causing the wind-speed distribution to transition from W-shaped to V-shaped. The results have significant implications for the design optimisation of wind energy harvesting. Moreover, they are potentially beneficial for the control of structural vibration using SHAWTs.

Development of a wind turbine for a hybrid solar-wind power system

Conventional energy supply has not been able to meet the energy needs of most developing nations. This calls for the need to invest in renewable energy systems which are not only sustainable but clean, abundant, and easily assessable. This research presents a study of wind variability by using wind data got from a weather station to design and fabricate a small-scale horizontal axis wind turbine (HAWT). This was done by using locally sourced materials for a Hybrid Solar-Wind power system for irrigation purposes, as a performance evaluation of the turbine. The materials used in the fabrication of the turbine include wood, polyvinyl chloride plastic, acrylic glass, Teflon, and steel all sourced locally. From the evaluation, the power capacity of the wind turbine was derived to be 40 W, 41 W and 43 W from the voltage and current output reading on the multi-meter from three average wind speed variations of 5 m/s, 10 m/s and 15 m/s measured from handheld digital anemometers respectively. A regression analysis of the relationship between the turbine's power capacity and the wind speed showed that the turbine operates best at low speed of 5 m/s, with an R2 value of 0.9602. The fabricated wind turbine was connected to a hybrid power system with the second energy source consisting of a 40 W solar tracking system to give a more stable power supply. The system was used for soil monitoring irrigation purposes. The design of the HAWT indicates a cheap, alternative and sustainable energy source that is more stable and suitable for smart solar panel irrigation system.

The Aerodynamic Performance of the Small-Scale Wind Turbine Blade with NACA0012 Airfoil

Small-scale wind turbine (SSWT) has been the subject of intensive research to complement its large-scale counterpart especially for usage in low wind speed regions. Two important issues that plague the development of the SSWT are its low in power coefficient especially due to the low Reynold’s number () condition that it’s operating in and the start-up difficulty that it faces. In this paper, the blade element momentum theory (BEMT) has been used to analyse a small-scale wind turbine having 3 m diameter. The airfoil used is the NACA 0012. The simplified experimental based equations have been used to determine the coefficient of lift, and coefficient of drag, of the airfoil. A developed MATLAB’s code applying the basic BEMT method is used. The results of aerodynamic performances including power coefficient, power and thrust are given as a function of wind speed, tip speed ratio (TSR) and Reynold’s number. It shows that at the minimum wind speed of 3 m/s, the wind turbine can have power coefficient of 43% but to produce 600 W of power that is required for total needs of electrical consumption of a household, the wind speed needed is 5m/s which is reachable for low wind speed region.

Enhancing Performance of Small Capacity Horizontal Axis Wind Turbine Using Grooved Linearized-Chord Blades

Abstract In the current article, E216 airfoil blades with linearized chord of a small-scale horizontal axis wind turbine are numerically investigated to enhance the performance of the turbine. The blade is modified by including grooves on its suction side. Three-dimensional Reynold’s averaged Navier–Stokes (RANS) simulations are performed with Shear Stress Transport k–ω as a turbulence model. The computed power-coefficient results are first validated with previous measurements by the present authors on a wind turbine of 1 m rotor diameter at two wind speeds of 6 and 8 m/s. Another validation with measurements from the literature is performed via comparison of the pressure-coefficient distribution along surfaces of E216 airfoil at an angle of attack of 6 deg. Based on the successful computation, six different rotor models are numerically investigated with different numbers and locations of grooves created along the blade length, from the hub to the tip region, on the blade suction side. The lift and drag coefficients are compared for the different simulated rotor models. Furthermore, the torque coefficient, thrust coefficient, and static torque coefficient are obtained for the simulated models. It is found that the best-simulated configuration is Model 1 having one groove at 80% blade-chord length from the leading edge, with a maximum power coefficient of 0.429 at a tip-speed ratio of 4.75. The aerodynamic performance of the blades is strongly affected by the groove on the suction surface. The results show that Model 1 blade reduces the generated mean-axial force and its vibration frequency on the rotor.

Shape optimization of a shrouded Archimedean-spiral type wind turbine for small-scale applications

Small-scale wind turbines are increasingly gaining importance despite they are still in the shadow of the megawatt-sized wind turbine development boom. Areas far removed from the electricity grid pose great potential for small-scale wind turbines. In such instances an Archimedean-spiral type wind turbine (ASWT) which is a new kind of horizontal-axis wind turbine maybe used for small-scale applications including off-grid power. The ASWT performance is improved in this work by designing a shroud with a flange at its inlet during an optimization technique aims to maximize the coefficient of power (Cp). The employed optimizer is an Evolutionary Algorithm over a Kriging interpolative model. A set of straight lines is applied to identify the shape of the shroud. The output power coefficient (Cp) is calculated by solving the Reynolds-averaged Navier-Stokes (RANS) equations with the SST k-Ω turbulence model using the commercial code software ANSYS-FLUENT. The simulation results are verified through GCI and validated with an experimental result. It is proved that the optimal shroud design yielded important enhancements in the Cp when it is applied to an ASWT. The results indicated that the optimal shrouded ASWT introduces a maximum Cp-value of 0.502, which is 2.58 times the Cp-value of the bare ASWT (Cp = 0.195) at λ = 2.5.

Shades of Green: Life Cycle Assessment of a Novel Small-Scale Vertical Axis Wind Turbine Tree

Are small-scale wind turbines green? In this study, we perform a ‘cradle to grave’ life cycle assessment of a novel domestic-scale 10 kW vertical axis wind turbine tree which uses combined Savonius and H-Darrieus blades. Situated at a test site in Surat Thani, Thailand, SimaPro software was used to evaluate the environmental impact profile of the tree. Comparisons to the Thai grid mix were made, using both with and without end-of-life treatments. Impact profiles were calculated using wind data collected over two years at Surat Thani, and from wind data from a higher capacity factor (CF) site at Chiang Mai, Thailand. Energy and greenhouse gas payback times were estimated for both locations. The relative magnitudes of impacts were compared with environmental prices protocol, and we investigated reductions in impacts using three mitigative scenarios: changes to design, transportation and materials. The results showed that Chiang Mai had a CF = 7.58% and Surat Thani had a CF = 1.68%. A total of 9 out of 11 impacts were less than the grid values at Chiang Mai, but at Surat Thani, 9 of 11 impacts were more than the grid values. End-of-life treatments reduced impacts by an average of 11%. The tower and generator were majority contributors to impacts (average 69%). Greenhouse gas and energy payback times were 28.61 and 54.77 years, and 6.50 and 12.50 years for Surat Thani and Chiang Mai, respectively, with only the Chiang Mai times being less than the turbine’s estimated lifetime. Location changes mitigated impacts most, followed by design, transportation, and then materials. We make recommendations to further improve the environmental impact profile of this turbine tree.

Mode interpretation of blade number effects on wake dynamics of small-scale horizontal axis wind turbine

The blade number of a wind turbine is a critical parameter that significantly affects its near-wake dynamics. In this study, we focused on the effect of the blade number on the wake of a small-scale horizontal-axis wind turbine (SHAWT) with a diameter of 0.18 m. An airfoil with a high lift coefficient was designed for a SHAWT model operating at a low Reynolds number. Large eddy simulation (LES) and optimal mode decomposition (OMD) were performed to identify the underlying coherence mode and to elucidate the wake dynamics. The LES results indicate that an increase in the blade number causes the double-peak velocity distribution to prematurely form a single peak shape. The effects of the blade number and tip speed ratio on the width and velocity deficit of the wake were also determined. The OMD results show that an increase in the number of blades results in the appearance of interharmonic modes with energies lower than that of the mean flow mode. Meanwhile, the increase in blade number causes early instability of the tip and hub/root vortices, leading to the break down and formation of patterns of streamwise vortices in the far wake. This leads to earlier wake recovery and influences the energy extraction and fatigue loads of the downstream turbines.

Numerical Investigation on the Effect of Profile and Blade Numbers in a Savonius Vertical Axis Wind Turbine

Small-scale wind turbines are considered recently as an attractive source of renewable energy, especially at remote area with respect to city centre. The design and characterization of a small vertical wind turbine are introduced through this work. A CFD analysis has been used as a first step in design to simulate the flow around the vertical blades of the small wind turbine. Different parameters have been taken into account in this work such as blades number, shape, and existence of stator blades deflector. Three different versions depend on blade profile have been examined. The turbulence model with sliding mesh in CFD have been performed. In this paper, a performance of small-scale of vertical wind turbine represented by CFD results of power coefficient, and optimal freestream velocity of this model are presented. The results showed that using 8 blades of VAWT instead of 4 blades with the same profile of blade has enhanced VAWT performance up to 64%. Also, increasing the concave profile of the blade can rise the torque produced by approximately 8%, however more increase in concave shape cause drop down by 5.6 %. Moreover, including stator deflector to the VAWT design has ability to increase the torque produced by 70 %. The output of these results will help to choose the optimum configuration of the small vertical wind turbine to implement this design experimentally as a next step.

Orta ve Küçük Ölçekli Rüzgar Türbinlerinin Yaşam Döngüsü Boyutunda Sürdürülebilirliği: Literatür Taraması

With the growing interest in renewable energy systems, studies on the sustainability of small-scale wind turbines have been published in recent years. A literature review was conducted in this study to compile scientific studies conducted to evaluate the environmental effects of medium and small-sized wind energy systems using the life cycle assessment. Life cycle assessment is a method of evaluating the environmental sustainability of a product, process, or system that is becoming more important in the context of decisions and policies in the energy sector. The environmental effects of medium and small-sized wind turbines on the life cycle size have been investigated in this study, which looked at studies conducted since 2004. The vast majority of these studies conducted environmental sustainability assessments based solely on a few environmental impact indicators such as global warming potential. There are only a few studies that consider a wider range of environmental effects. The collection and analysis of studies examining the life cycle environmental sustainability of medium and small-scale wind turbines are important for determining the future vision of small-scale energy production systems.