Vertical Axis Wind Turbine Research Articles

Effect of background turbulence on the wakes of horizontal-axis and vertical-axis wind turbines

We report a wind tunnel study on the wake generated by a horizontal-axis (HAWT) and a vertical-axis wind turbine (VAWT). Two scaled models, one of each type, have been tested in a wind tunnel, under low blockage and at Reynolds numbers, based on the rotor diameter D, of ReD=265×103 for the HAWT and 330×103 for the VAWT. The models scale with respect to the largest commercially deployed turbines is of 1/383 and 1/65.5, for the HAWT and the VAWT, respectively. Furthermore, two different inflows were tested: low and moderate turbulence conditions. For each type of turbine and inflow, different values of tip-speed ratio and ReD were tested.Hot-wire anemometry was used to characterize the wake at different streamwise positions, exploring the range 1<x/D<30 for the HAWT and 1<x/D<15 for the VAWT.We find that, under a low-turbulence inflow, both turbines generate significantly different wakes, characterized by the velocity deficit, wake width and the profiles of average and rms streamwise velocities. More specifically, in low-turbulence conditions, the VAWT presents faster recovery than the HAWT. Remarkably, we observe that a moderately turbulent inflow results in similar wake shapes for both turbines, presenting similar recovery and structure under all studied conditions.

Modification to traditional vertical axis wind turbine system to implement permanent magnet propelling phenomenon as measure of performance enhancement

The environmentally friendly, easily available and affordable alternative energy sources are one of the important requirements for the growth of the modern world. This research work explains how the magnetic repulsion characteristics of permanent magnets could be used as the energy source to meet energy demands. The wok is carried out on the permanent magnet propelled vertical axis wind turbine and its performance is compared with the traditional vertical axis wind turbine. The results show that the permanent magnet propelled wind turbine will function much better than the traditional one, even at slower wind speeds. The magnetic repulsive properties are used as a supplementary energy source in a permanent magnet propelled vertical axis wind turbine, which add kinetic energy to the turbine’s rotational momentum, while transforming wind power to mechanical movement.

Performance analysis of the blade for the v-shaped vertical axis wind turbine

Performance analysis of the blade for the v-shaped vertical axis wind turbine

Optimizing a vertical axis wind turbine with helical blades: Application of 3D CFD and Taguchi method

Vertical axis wind turbines (VAWT) with helical blades are being interested in urban areas due to the low dependency on the wind direction and also due to low noise production. In spite of good self-starting and smooth operation as the advantages of this type of turbine, its optimizing has not been reported in literature yet and is the subject of this research. A primary investigation by 3D computational fluid dynamics (CFD) to simulate the air flow about the above type of VAWT in the first step showed the importance of three design variables of tip speed ratio, helical angle, and airfoil chord length. However, in the second step, CFD runs were very time consuming and costly. For considering five values for each design variable, 53=125 cases had to be simulated by 3D CFD. Thus, by the use of Taguchi method and with definition of an orthogonal array named L-25, the number of required 3D CFD simulations reduced from 125 to 25. Then, the optimum values of variables were obtained as 1.33 for the tip speed ratio, 30 degrees for the helical angle, and 0.4 m for the airfoil chord length. At the optimum point, the average power coefficient increased to 0.17542. The presented research is novel for optimizing VAWT with helical blades.

Recent advances in VAWT aerodynamic performance research: Optimal design

Vertical axis wind turbine is a popular research direction in recent years, and its aerodynamic performance directly affects its power generation efficiency. Using CFD method simulation, the aerodynamic characteristics of wind turbine blades can be deeply analyzed. In this paper, the numerical simulation progress of the aerodynamic performance of vertical axis wind turbines with airfoil as the main object in recent years is studied, the influence of different design parameters on the performance of wind turbines is discussed, the characteristics of current research are summarized, and the future research trends are prospected.

Vibration control of the straight bladed vertical axis wind turbine structure using the leading-edge protuberanced blades

This study investigates the impact of structural responses resulting from alterations in aerodynamic characteristics caused by incorporating leading-edge protuberance (LEP) blades in vertical-axis wind turbines (VAWTs) under various wind speeds. The current experimental investigation was conducted on a scaled-down straight-blade VAWT with multiple wind speeds at a fixed pitch angle and uniform blade configuration. The unsteady structural excitation caused by the decay of vortices due to the different aerodynamic loads and its effect on the VAWT structure is examined in great detail. The presence of counter-rotating vortices from the LEP profile, however, enhances the aerodynamics of the blades at higher angles of attack. It is crucial to understand the structural characteristics resulting from changes in aerodynamics. The paper presents the effects of the LEP on the structural excitation of the VAWT by analyzing the acceleration and displacement data obtained from the static structure of VAWT for various operational wind speeds. The results showed decreased acceleration and displacement amplitudes for the VAWT with LEP at medium and higher wind speeds. Significant aerodynamic and structural damping was observed in the VAWT with LEP blades. The results obtained were in close agreement with the time and frequency domains of the measured displacement and acceleration from the structure. The bidirectional vibration control was observed for the VAWT with LEP, which was found to have a reduction ratio of 70 %.

Determining Payback Period and Comparing Two Small-Scale Vertical Axis Wind Turbines Installed at the Top of Residential Buildings

In recent years, residential buildings have seen a notable increase in energy consumption. To address this, it is crucial for researchers to invest in renewable energy technologies, aiming to develop highly sustainable and nearly-zero energy buildings. Many countries are started to commit to this goal, seeking to phase out fossil fuels due to their harmful environmental effects. Wind energy stands out as a promising renewable resource, especially in areas with strong wind patterns. This study focuses on a case in Karaburun, Izmir province, Türkiye, where annual wind speeds range from 6 to 8 m/s and evaluates the performance of two types of small-scale Vertical Axis Wind Turbines (VAWTs) in reducing energy consumption in a three-story residential building, along with associated costs. Utilizing advanced simulation tools like ANSYS Fluent and DesignBuilder Software, the study examines Ice-Wind VAWTs and Savonius VAWTs. The findings reveal that installing 15 Ice-Wind VAWTs on the building's roof can reduce energy consumption by approximately 22.5%, with each turbine costing about $2000 and a payback period of around 14.57 years. Conversely, using 15 Savonius VAWTs can reduce energy consumption by 36%, with each turbine costing about $2300 and a payback period of around 8.93 years. These results indicate that the Savonius turbine offers a faster return on investment compared to the Ice-Wind turbine under the specified conditions. Overall, this study highlights the significant benefits and cost implications of integrating renewable energy solutions like VAWTs into residential buildings.

Aerodynamic efficiency assessment of a cross-axis wind turbine integrated with an offshore deflector

The present work examines the performance of an offshore cross-axis wind turbine (CAWT) with a flow deflector by integrating numerical and analytical methods. The deflector's geometry redirects flow in all directions, causing it to exit vertically and collide with the wind turbine's horizontal blades. In contrast, the blades of a vertical axis wind turbine (VAWT) harness the power of horizontal wind flow. The total power absorbed by the horizontal and vertical turbine blades represents the power of CAWT. In this study, the speed of the outflow from the deflector was initially determined through numerical simulation. The numerical simulation output was then utilized as an input for analytical Double Multiple Stream Tube (DMST) and Blade Element Momentum (BEM) methods to evaluate the vertical and horizontal turbine blades, respectively. This approach reduces the overall simulation time and establishes an offline coupling between analytical and numerical approaches. The findings of this research have unveiled a promising future for offshore wind energy generation. Through the implementation of a modeled deflector on a Cross-Axis Wind Turbine (CAWT), the power output reached a remarkable 19 KW with a power coefficient of 0.35 at an 8.4 m/s wind speed. The results indicate that the CAWT with the deflector produced a power output 35 % higher and was 45 % more efficient than a single Vertical-Axis Wind Turbine (VAWT). These outcomes illustrate the potential for greater energy production and efficiency in offshore wind farms.

Power performance enhancement for a three-turbine cluster of two-stage Savonius rotors using Taguchi approach

Choosing an optimal Savonius vertical-axis wind turbine (VAWT) arrangement that delivers the largest power coefficient is a significant challenge. So, in this paper, an optimization of the power performance using the Taguchi technique is presented for a three-turbine cluster of two-stage Savonius rotors. A three-dimensional, unsteady, incompressible airflow model is numerically solved using ANSYS and validated using published experimental and numerical studies. The power performance of the three VAWTs is optimized by adjusting five factors, including the relative angles between the turbines (ϕ12 and ϕ13), the rotation directions (RD), and the turbine spacings (S12 and S13). The rated power coefficient (CP) and its corresponding Tip Speed Ratio (TSR) are numerically obtained for an L16 (45) orthogonal array (OA). After the signal-to-noise ratio analysis, the optimal case is obtained. Results indicate that the configuration angles have the main effect on CP, the turbine spacing between the first and second rotors and the combination of rotation directions have the lowest effect. The optimal case is found to be (S12 = 2D, S13 = 2.4D, ϕ12 = ϕ13 = 70⁰, and RD = -, +, -), resulting in an increase of 19.69 % in CP compared to the isolated turbine at a rated TSR of 0.8.

Performance and mechanism of adaptive pitch control in a floating vertical axis wind turbine with a surge motion

Floating vertical axis wind turbines are bearing complex aerodynamic fatigue loads due to the movement of the platform and the reciprocating variations in the angle of attack and the blade relative wind speed. To explore the effect of the surge motion of the platform and verify the performance and acting mechanism of adaptive pitch control on reducing the fatigue loads and improving the power coefficient, a floating vertical axis wind turbine with three motion forms (non-surge, pure surge, and surge-adaptive pitch) is investigated in the condition of a low tip speed ratio with a high incoming wind speed. The results show that the surge motion enhances the fatigue loads, with the power coefficient less affected. The adaptive pitch control reduces the enhanced fatigue loads and improves the power coefficient by nearly twice. Vorticity and pressure distributions verify that the fluctuation ranges of the angle of attack and the blade relative wind speed are expanded by the surge motion, and the angle of attack is reduced by the adaptive pitch control especially in the upwind section, with the flow separation mitigated. However, the effects of the surge motion and the pitch variation are also influenced by the shedding vortex and the flow separation reattachment. For the upwind part of the blade aerodynamic forces, with the surge amplitude increase or the surge period decrease, the global amplitudes are increased gradually by the surge motion and then reduced by the pitch control, with the load reduction performance enhanced gradually.

Variable designs of vertical axis wind turbines—a review

Variable designs of vertical axis wind turbines—a review

A Study on the Effect of Turbulence Intensity on Dual Vertical-Axis Wind Turbine Aerodynamic Performance

Examining dual vertical-axis wind turbines (VAWTs) across various turbulence scenarios is crucial for advancing the efficiency of urban energy generation and promoting sustainable development. This study introduces a novel approach by employing two-dimensional numerical analysis through computational fluid dynamics (CFD) software to investigate the performance of VAWTs under varying turbulence intensity conditions, a topic that has been relatively unexplored in existing research. The analysis focuses on the self-starting capabilities and the effective utilization of wind energy, which are key factors in urban wind turbine deployment. The results reveal that while the impact of increased turbulence intensity on the self-starting performance of VAWTs is modest, there is a significant improvement in wind energy utilization within a specific turbulence range, leading to an average power increase of 1.41%. This phenomenon is attributed to the more complex flow field induced by heightened turbulence intensity, which delays the onset of dynamic stall through non-uniform aerodynamic excitation of the blade boundary layer. Additionally, the inherent interaction among VAWTs contributes to enhanced turbine output power. However, this study also highlights the trade-off between increased power and the potential for significant fatigue issues in the turbine rotor. These findings provide new insights into the optimal deployment of VAWTs in urban environments, offering practical recommendations for maximizing energy efficiency while mitigating fatigue-related risks.

Comparative study of dynamic characteristics between a FHAWT and a helical type FVAWT

Floating offshore wind turbines (FOWTs) are a growing area of interest, with significant ongoing research work and commercial development. There are two types of FOWT, namely floating horizontal axis wind turbine (FHAWT) and floating vertical axis wind turbine (FVAWT). It has been a long-standing debate on which type of FOWT has better technical and economic performance. However, the research work on comparative study of these two types of FOWT is very rare. In this study, we aim to systematically evaluate the performance of FHAWT and FVAWT, with particular focus on comparing their dynamic characteristics by using coupled numerical models. Tank testing for these two types of FOWT was conducted at the wave basin, and a series of code-to-experiment comparisons were carried out to validate the numerical models. Afterwards, dynamic characteristics, including the control strategy, aerodynamic power, floater motions, tower base bending moments, and blade deformations, are compared between the FHAWT and helical type FVAWT. Results show that the FHAWT presents better performance on the aerodynamic performance and tower base bending moments, while the helical type FVAWT has the advantage of minimal blade deformations.

Drag reduction of lift-type Vertical axis wind turbine with slit modified Gurney flap

This study examines aerodynamic performance enhancement of Vertical Axis Wind Turbine (VAWT) blades with Gurney flap (GF) modified by slits. A quasi-3D computational fluid dynamics solution based on Reynolds-averaged Navier-Stokes model is employed to evaluate the effectiveness of slit GF blades, in particular the lift-to-drag ratio. The computational domain includes three pairs of GFs and slits combination along the blade span-wise direction to allow quasi-3D flow development while applying translational periodic boundary condition on the two end-wall boundaries. The inlet velocity is 9 m/s for a VAWT configuration with Tip Speed Ratios (TSRs) of 1.44, 2.64, and 3.3, respectively and each of these TSRs represents low, medium, and high regimes of TSRs. Simulation results have shown a significant 8% drag reduction for blades with slit GFs at medium range of TSRs, albeit with a 2% decrease in lift compared to blades with clean GFs. This improves the lift-to-drag ratio and enhances moment production. The power generation also shows increases of 1.5%, 6.5%, and 11.3% at low, medium, and high TSR regimes, respectively, for the analysed slit GF blades. The drag reduction is primarily attributed to the generation of small-scale vortices by the slit, dissipating large coherent flow structures more rapidly in the near wake-field.

Ameliorating a vertical axis wind turbine performance utilizing a time-varying force plasma actuator

Controlling wind flow on vertical axis wind turbine blades is an effective technique for enhancing their performance. Modern equipment such as plasma actuators have gained significant attention for their ability to control, and improve the flow behavior in wind turbines. Previous studies have primarily focused on investigating plasma actuators with constant force. In this study, plasma actuators with varying forces over time were applied to the turbine blades. An unsteady 2D model was used to analyze the wind turbine. The sliding mesh model was employed to simulate rotor rotation, and the SST k-ω\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$k-\\omega $$\\end{document} model was utilized for turbulence modeling. Initially, the performance of the clean turbine was examined. In the next step, the plasma actuators with different force waveforms were applied to the wind turbine blades, including constant, sine, cosine, positive ramp, negative ramp, pulse in the first half-cycle, and pulse in the last half-cycle waveforms. The results indicated that the cosine, and sinusoidal waveforms, led to the greatest improvement with 37.28% and 35.59% increase in the net energy produced by the turbine, respectively, compared to the baseline case.

Can bird, cetacean, and insect inspired techniques improve the aerodynamic performance of DU 06 W 200 airfoil applied in vertical axis wind turbines?

ABSTRACT To achieve a better aerodynamic performance of wind turbines, the selection of a proper airfoil plays a crucial role. Generally, aviation airfoils (such as the NACA series) were widely used in the design of wind turbine blades due to their aerodynamic characteristics. However, several studies have shown that there are a number of defects in the application of aviation airfoils for blade design, such as poor stall characteristics or incompatible performance at different Reynolds numbers. The aerodynamic performance and lift force of newly developed airfoils inspired by cetaceans, birds, and insects were numerically investigated by CFD in the range of Reynolds number of 1.2 × 105 to 1.7 × 105 and a range of angles of attack (from 0° to 25°). ANSYS Fluent and the Shear Stress Transport (SST) k-ω turbulence models were selected to analyse the pressure and velocity distributions around the airfoils. In addition, the aerodynamic efficiency was calculated for all different cases. For verification and comparison, DU 06-W-200 airfoil was also simulated under the same operating conditions. Results revealed that several of these new bio-inspired designs can increase the aerodynamic performance of the DU 06-W-200 airfoil by up to 24.7%, with the bird-inspired airfoils presenting the best performance among all designs, and the best options for the design of vertical axis wind turbine (VAWT) blades.

Technical and economic feasibility of a small vertical axis wind turbine in low wind conditions compared to other power sources for pumping water

In a global context, the significance of transitioning to renewable energy sources is paramount for sustainable development. This relevance is particularly evident in Brazil, where significant strides have been made in microgeneration of photovoltaic solar power and on-shore large-scale horizontal-axis wind power. Despite the country's extensive energy capacity from hydroelectric facilities, still approximately 38.5 million people reside in rural areas and surrounding areas, emphasizing the need for effective and affordable energy solutions for these regions. Based on this social and business opportunity of small-sized devices used in sustainable development, this practical experimentation explores the viability of initial studies from a prototyped small vertical-axis wind turbine (VAWT) system for water pumping, comparing its technical and economic feasibility with commercial off-the-shelf (COTS) photovoltaic solar pump (PV) and conventional electrical pump systems (EP). Two scenarios are investigated: (1) a patented transmission mechanism connected to a double effect pump and (2) the VAWT system designed to be connected to the same mechanism. Compared to PV ‘systems, scenario (1) offers 1.4x higher flowrate at a significantly lower cost (137% less) and consumes half the power. It offers a lower flowrate (2.6x) than EP systems but at a lower cost (36% less) and consumes one-third the power. Scenario (2) provides 2.7x less water flow than PV at a slightly lower cost (41% less). While less efficient in water flow (10 x) compared to EP, it has a slightly higher cost (15% more). This research builds upon existing knowledge and offers valuable insights for future small VAWT applications in low-wind remote areas for water pumping.

Overall aerodynamic performance of the airfoils with different amplitudes via a fuzzy decision making based Taguchi methodology

In this study, the overall aerodynamic performance of the airfoils with variable amplitude geometric structure for lift-type vertical axis wind turbine has been analyzed and optimized using Fuzzy Analytic Hierarchy Process (AHP)-Fuzzy COmbinative Distance-based Assessment (CODAS) based on Taguchi Method. In the design of the experiment, leading edge (LE) tubercle airfoil models, Reynolds number, and angle of attack are utilized as the control factors. Drag, lift, and lift to drag ratio performances by comparing the airfoils according to the baseline model are calculated and the combination of these performances is considered as the overall aerodynamic performance response. The experiments are carried out according to the orthogonal matrix L18. Since the importance of each response is different on lift-type vertical axis wind turbines, the importance weights of these responses were obtained by Fuzzy AHP according to the evaluation of the decision maker. Multiple responses are converted into a single response (the overall aerodynamic performance) via Fuzzy CODAS which enables to model uncertainty in order to overcome the physical effects that may arise in experiments. Thereby, a multi objective Taguchi methodology was applied for the overall aerodynamic performance with a novel Fuzzy logic based multi criteria decision analysis approach. As a result, Model-4, having tubercle design parameters of amplitude of 0.025c and 0.0125c and wavelength of 0.5c and 0.125c, was found to have the best performance with the novel Taguchi approach, which saves time and cost. In addition, it has been determined that the airfoils, Reynolds number and angle of attack are significant and what level of contribution to the overall aerodynamic performance. At this point, the most important control factor has emerged as the angle of attack.

A Prototype Design of a Vertical Axis Wind Turbine as One of the Renewable Energy Sources in Brunei

Background: According to the Asia Wind Energy Association, Brunei can harness the power of wind energy to meet its future demands for a reliable energy source that is both renewable and non-polluting. Objective: A preliminary study to design and manufacture wind turbines needs to be initiated earlier especially in the Brunei with has potential wind energy. Methods: This preliminary study compares several Vertical Axis Wind Turbine (VAWT) types and examines the optimal design in terms of mechanical parts for wind speed characteristics in Brunei. The project focuses on the engineering design stages to obtain a selected design that differs from other available designs. Results: The preliminary study successfully generated a small amount of electricity from the mechanical rotation of the VAWT. Conclusion: Although the preliminary study can generate a small amount of electricity, several design parameters need to be improved in further study. Proper manufacturing technologies are also needed to fabricate a better VAWT.

Multi-objective optimization on blade airfoil of vertical axis wind turbine

Multi-objective optimization on blade airfoil of vertical axis wind turbine