Design Of Vertical Axis Wind Turbine Research Articles

Low-speed wind energy generation devices to facilitate NZEB in urban Pakistan

Energy consumption and its resultant impact on climate change are inextricably linked, with the burning of fossil fuels being a chief contributor to greenhouse gas emissions, furthering global warming. Mitigating these effects necessitates a two-fold approach: reducing energy consumption through enhanced efficiency and behavioral modifications, and concurrently transitioning to renewable and clean energy sources. Of particular concern is the domestic and commercial building sector, which currently accounts for a substantial 40% of the world's total energy usage. Conventional wind turbines, effective in harnessing wind energy, face limitations in urban areas due to the requisite wind speeds. Micro wind turbines, notably Vertical Axis Wind Turbines (VAWT), present a promising solution for achieving net-zero energy buildings in urban settings. VAWTs exhibit advantages such as higher efficiency and lower cut-in speeds. Despite their promise, challenges like reliability, cost, and environmental impact persist. This concise overview suggests potential applications for Pakistan, emphasizing the imperative for further exploration in optimizing VAWT design, developing hybrid systems, and evaluating societal acceptance of rooftop wind farms.

Validation of the structural response of a 70kW VAWT

This paper describes a project for predicting and measuring the structural response of a 70 kW vertical axis wind turbine (VAWT), while offering insights for optimizing efficiency and ensuring longevity. We employ the traditional frequency response approach and model the turbine behavior using its stationary modal shapes. Results for three key sensor locations – lower central mast bending, upper blade flapwise bending, and central horizontal arm out-of-plane bending – reveal that the codes accurately predict the critical resonance and capture the dominant harmonic amplitudes. In addition, it is shown how a statistical treatment of the steady state solution can lead to predictions of the fatigue cycle distribution enabling accurate life predictions. The program demonstrates the potential to significantly improve the design and operation of VAWT using simple, steady state, simulation codes for capturing VAWT aerodynamics. The model demonstrates sufficient accuracy while offering computational efficiency compared to more complex models.

Optimization of VAWT installation with spatial and temporal complexity considerations

The constant need for fuel to meet the commercial sector’s ever-increasing demand has driven researchers to discover and optimize renewable energy resources, paving the way for sustainable production of reliable and clean energy resources. The goal of the current work is to close the gap in process parameter optimization needed to convert wind energy wake from traffic on highways into electrical energy utilizing vertical-axis wind turbines (VAWTs). The energy output from the VAWT is analyzed to investigate how it is impacted by the variations in multiple parameter settings. Using the central composite design (CCD), a three-level four-factor array was used to investigate the following parameters: VAWT vertical distance (VD) and horizontal distance (HD) as continuous parameters, while road side (S) and location (L) of VAWT as categorical parameters. To find the most important parameter, response surface methodology (RSM) optimization and an analysis of variance (ANOVA) test are performed. L accounts for 66.67% of the total variable, with S coming in second with 51.80%. Using the best results from RSM and ANOVA, a confirmation test is run, and the results show yields of 88.75% ± 0.05% and 87.5% ± 0.05%, respectively. Therefore, RSM and ANOVA can be utilized equally for optimization at the same VAWT design. Lastly, the findings of the economic and environmental evaluation demonstrate that, in comparison to the basic settings, VAWT operating at optimal settings can save up to 180% and 200% more energy and reduce carbon emissions, respectively.

Innovative multiobjective optimization of a curved‐blade vertical axis wind turbine modeled by modified double multiple streamtube method

AbstractThe attractive specifications of vertical axis wind turbine (VAWT) are its operating with low noise and wind in various directions. To achieve a higher performance of these turbines, modeling of a curved‐blade VAWT by the modified double multiple streamtube (DMST) method and optimizing this wind turbine are performed. The power coefficient and the total normal force acting on blades were selected as two objective functions. Minimizing the normal force acting on turbine blades as the second objective function was not observed in the open literature. The amount of normal force is crucial in the structural design of VAWT because it generates both the bending moment on blades and forces on supporting arms of VAWT. Another innovation of this study is to consider the shape coefficient parameter that determines the shape of the rotor geometry as a design variable in optimization procedure. A 3 m height curved‐blade VAWT type was optimized by this multi‐objective optimization technique. The optimum values of the design variables obtained by the Genetic Algorithm were selecting an elliptical rotor geometry, pitch angle −1.4°, diameter/height 1.3, blade aspect ratio 19.8, tip speed ratio 4.3 and selecting three blades which could provide a power coefficient of 0.49 and a normal force of 158.7 N.

Vertical Axis Wind Turbine for Low Wind Speed Environment: Effect of Scoop Harmony Blade

The wind condition in Malaysia is in the low-speed category with an average speed of 1 ms-1 to 4 ms-1. Effect of ground level relies significantly on the wind speed distribution. Despite these conditions, it is less suitable for the development of horizontal wind turbine as an energy source. The obvious weakness is the lack ability to self-start and predict the wind direction thus affects the energy efficiency output. To overcome this problem, improvement of the vertical axis wind turbine design is observed to be the solution in replacing horizontal axis wind turbine. Hence, this study is to investigate a suitable type of vertical axis wind turbine blade design for the best performance RPM output in a low-speed wind environment. The investigation was conducted in a Longwin LW-9300R subsonic wind tunnel at 0 ms-1 to 10 ms-1 wind speed condition from three wind turbine blades specified as Solid Harmony, Scoop Harmony and Conventional Savonius blade with angle of 90º, 135º and 180º to determine the highest RPM productivity. Result shows that Scoop Harmony blade delivers the highest RPM blade output while Savonius 180º is seen to have the highest self-start blade achieved at 64 rpm at 1 ms-1 wind speed. However, Solid Harmony shows an acceptable range TSR of 0.5 with difference of 23% lower than Scoop Harmony. This shows that both Scoop Harmony has a higher performance RPM but Solid Harmony still has the potential design to be applied at low-speed condition due to its low TSR output.

CFD Modeling of a Pitching Airfoil for the Estimation of the Performance Curve in an H‐Rotor Vertical Axis Wind Turbine

In this work, the performance curve of a straight‐bladed vertical axis wind turbine (VAWT) is estimated through a CFD two‐dimensional modeling of a single airfoil under unsteady pitching motion. A typical URANS approach, with a k‐ω SST turbulence model and UDF functionalities, has been employed to simulate a fixed airfoil under variable inlet conditions. Induction factors are previously computed using a simple stream tube model (SSTM) in an iterative process. Frequencies and amplitudes of the pitching motion are modified to simulate the operative range of tip‐speed ratios (TSRs) for the wind turbine. The obtained results have been compared with experimental curves of a 0.5 solidity turbine measured in a wind tunnel. The experimental results of the wind‐tunnel turbine provide a maximum Cp value of 0.22 at a TSR = 3.1, while the numerical procedure estimates a value of 0.33, also at TSR = 3.1. Despite of the discrepancy, due to the 2D assumptions in the simulation, the procedure makes reliable and more accurate estimations than traditional analytical models with steady coefficients. This alternative methodology significantly reduces the computational cost. Moreover, these nonrotating simulations allow more robust and practical routines that can be easily implemented in optimization algorithms for the design of VAWTs.

Enhancing vertical axis wind turbine efficiency through leading edge tubercles: A multifaceted analysis

This research paper aims to investigate the impact of leading edge tubercles (LET) on the performance of hybrid vertical axis wind turbine (VAWT). The study involves both experimental and computational analysis of a novel hybrid VAWT configuration. The proposed VAWT design is characterized by a high power coefficient and self-starting capability. To provide a basis for comparison, an existing hybrid VAWT without tubercles and a conventional H-Rotor Darrieus design were also examined. The findings indicate that the proposed hybrid VAWT achieved the highest power coefficient (Cp) of 0.475 at a tip speed ratio (TSR) of 3. Furthermore, the proposed wind turbine demonstrated superior Cp values at both low TSRs (1 to 2.1) and high TSRs (4.1 to 5) compared to the existing hybrid VAWT and the H-Rotor Darrieus turbine. The positive static torque coefficient (Cts) values observed at all azimuths, with a maximum value of 0.319, highlight the self-starting capability of the proposed hybrid wind turbine. The enhanced power coefficient and the ability to harness wind energy even at low wind speeds make the proposed hybrid wind turbine suitable for a wide range of power projects, from small to large-scale. This approach offers a means to determine the optimal design configuration for a hybrid VAWT and facilitates a detailed analysis during the early design stages, along with its high-fidelity characteristics.

Power performance and self-starting features of H-rotor and helical vertical axis wind turbines with different airfoils in turbulence

Wind tunnel tests were conducted to systematically assess the aerodynamic performance of both H-rotor and helical vertical axis wind turbines (VAWTs) in smooth and turbulent flows. The effects of airfoil section and pitch angle β on the power and self-starting performance were examined for both types of turbines. The helical turbine had a wider operating range of tip speed ratios (TSR λ) and much lower power performance than its H-rotor counterpart. This phenomenon was attributed to the flow deflection of helical blades due to their three-dimensional features, as well as that dynamic stall of a helical blade would not occur simultaneously for all blade elements. The helical turbine did not exhibit notably improved self-starting performance despite of the high manufacturing cost. Moreover, the start-up process was analyzed by using the static torque coefficient CT of both single-bladed and three-bladed turbines. It was found that turbulence intensity exercised a significant impact on CT. Turbulence would cause serious fatigue issues for H-rotor turbines and change the driving mechanism of helical turbines though it enhanced the self-starting performance. Recommendations were finally provided for the design of VAWTs in built environments.

Experimental investigation and analysis of proposed hybrid vertical axis wind turbine design

In this research, an experimental and computational analysis of a novel hybrid vertical axis wind turbine (VAWT) arrangement has been performed. We suggest an innovative VAWT design that has a high power coefficient and self-starting capability. The inner side of the proposed hybrid system has been integrated with the H-rotor turbine with cambered blades, which demonstrates strong self-starting capabilities at various azimuths. Three NACA0018 airfoil blades are mounted on the outside of the proposed hybrid wind turbine, while three DU 06-W-200 airfoil blades are installed on the inside. Based on a similarity analysis, a scaled-down model was developed, and performance characteristics such as the output power, power coefficient ([Formula: see text]), dynamic torque coefficient ([Formula: see text]), and static torque coefficient ([Formula: see text]) were determined. An existing hybrid VAWT and a typical H-rotor Darrieus design were also examined for comparison. The highest [Formula: see text] for the proposed hybrid design was found to be 0.486 at a tip speed ratio (TSR) of 3, while the H-rotor Darrieus’ maximum value was 0.42 at a TSR of 2.62 and the existing hybrid VAWT’s value was 0.41 at a TSR of 2.5. Positive [Formula: see text] values at all azimuths demonstrate that the proposed hybrid wind turbine can start entirely on its own. In comparison to the existing H-rotor and hybrid VAWT, this novel hybrid system has shown enhanced performance parameters ([Formula: see text], [Formula: see text], [Formula: see text], output power) by around 11%–13% over a wide range of wind speeds.

The Optimization of Savonius Helix Wind Turbine Cut-in Speed with the Variation of Blades-twist Rotor and Number of Blades

Wind turbines are typically classified as Horizontal Axis Wind Turbines (HAWT) or Vertical Axis Wind Turbines (VAWT). VAWT has a superior ability to accelerate from rest to rotation than HAWT, allowing it to rotate the rotor even when the wind speed is low; additionally, the produced torque is relatively high. Using the Savonius helix VAWT is one of the numerous methods for enhancing VAWT performance. The effect of the number of blades and the blade twist of the rotor or the angle of rotation of the blades on the rotor from the bottom end to the top end on the speed cut generated by the VAWT Savonius helix was investigated experimentally. Variations in the number of blades used in the study included 2 and 3 blades, as well as 90°, 180°, 270°, and 360° for the rotor twist blades. In a wind tunnel, data was collected at wind speeds ranging from 0 to 5 m/s. The best performance research results were obtained With three blades, a twist angle of 180 degrees, and a cutting speed of 1.51 m/s. By modifying the Savonius Helix VAWT design in this study, it is possible to increase the efficiency and performance of turbines, mainly when used at low wind speeds, and the potential for using wind energy as a more efficient and sustainable alternative energy source.

Aerodynamic performance optimization of vertical axis wind turbine with straight blades based on synergic control of pitch and flap

Low power efficiency is a critical reason that restricts the potential application of the vertical axis wind turbine (VAWT) in offshore engineering. Hence, efficiency enhancement is an essential topic for the VAWT design. This paper attempts to propose an improved active control strategy and a novel blade structure with a trailing-edge flap for H-type VAWT to improve the power outputs at different tip speed ratios (TSRs). The orthogonal experiment design (OED) method was applied to optimize the motion of pitch and flap at low and moderate TSRs. Subsequently, the output characteristics, including the coefficients of power, torque, tangential force, and thrust of the optimized pitch-flap (P-F) model and three other models, namely the base model, the pitch-only (P-O) model, and the flap-only (F-O) model, were compared. Besides, the flow structures and static pressure distribution on the blade surface were studied to reveal the mechanism of power increase. It was found that the synergic motion of pitch and flap could effectively suppress the flow separation and delay the dynamic stall around blade. The result indicated that enhancement of the P-F model in torque coefficient was over 130% and 60% at low and moderate TSRs compared to the base model. In addition, the synergic motion of pitch and flap was found able to reduce the load fluctuation of the VAWT. The improved active control strategy and the blade structure with a trailing-edge flap may be helpful for the potential application of the H-type VAWT in offshore engineering.

Enabling Floating Offshore VAWT Design by Coupling OWENS and OpenFAST

Vertical-axis wind turbines (VAWTs) have a long history, with a wide variety of turbine archetypes that have been designed and tested since the 1970s. While few utility-scale VAWTs currently exist, the placement of the generator near the turbine base could make VAWTs advantageous over tradition horizontal-axis wind turbines for floating offshore wind applications via reduced platform costs and improved scaling potential. However, there are currently few numerical design and analysis tools available for VAWTs. One existing engineering toolset for aero-hydro-servo-elastic simulation of VAWTs is the Offshore Wind ENergy Simulator (OWENS), but its current modeling capability for floating systems is non-standard and not ideal. This article describes how OWENS has been coupled to several OpenFAST modules to update and improve modeling of floating offshore VAWTs and discusses the verification of these new capabilities and features. The results of the coupled OWENS verification test agree well with a parallel OpenFAST simulation, validating the new modeling and simulation capabilities in OWENS for floating VAWT applications. These developments will enable the design and optimization of floating offshore VAWTs in the future.

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.

Performance enhancement of a vertical axis wind turbine using a slotted deflective flap at the trailing edge

Vertical axis wind turbines (VAWTs) exhibit dynamic stall under operational conditions which causes boundary layer separation from the surface of the blade. This hinders the turbine’s overall performance in which the turbine displays low efficiency, aerodynamic losses, and vibration and noise generation. The aim of this study is to optimize the performance of an H-type Darrieus VAWT by employing a single-slotted deflective flap at the trailing edge of the blade. To optimize the turbine’s performance, Computational Fluid Dynamics (CFD) and Design Of Experiments (DOE) methods are utilized simultaneously for time-saving purposes. The design parameters optimized for the NACA 0018 airfoil are the flap’s gap (Δy), overlap (Δx), and deflection angle (δf). The influence of each parameter on the performance of the VAWT are determined by DOE, which yields the optimum combination of design parameters for this H-rotor VAWT as Δx = 2 mm, Δy = 0.5 mm, and δf = 90 at TSR 3 where two-dimensional (2D) and three-dimensional (3D) CFD simulations yield turbine power increments of 27 % and 19 %, respectively. The flow characteristics of the 2D and 3D turbine models with slotted blades, developed using ANSYS Fluent R2020, demonstrated a delay in boundary layer separation and a reduction in vortices shedding due to the high-pressure flow through the slot, which in return reenergizes the boundary layer. The results from this study indicate an improved design of an H-rotor VAWT.

Response Surface Optimisation of Vertical Axis Wind Turbine at low wind speeds

The Vertical Axis Wind Turbines (VAWTs) have an increasing global market and this emphasis the need for to improve the performance of VAWTs, especially at relatively low wind speed. This paper utilises the Response Surface methodology to optimise the performance of a VAWT. A three bladed VAWT configuration was considered with a NACA0015 profile. Three significant input parameters were selected including the tip speed ratio, the turbine solidity, and the pitch angle. An extended range of each input parameter was chosen in order to gain a good insight into how these input parameters affect the performance of the VAWT. The high-fidelity Computational Fluid Dynamics (CFD) simulations were carried out for the modelling of the turbine. The use of the Response Surface Optimisation based on Multi-Objective Genetic Algorithm (MOGA) along with the CFD simulations is found to be useful in the selection of the optimal design of VAWT. Moreover, the 3D aspects of the VAWT geometry are investigated and these include the turbine aspect ratio and the effect of the blade tip geometry. The implementation of an optimised winglet at the tip of the turbine blades is found to provide a significant enhancement of the cycle averaged power coefficient, especially at low aspect ratios.

Computational Investigation of Vertical Axis Wind Turbine in Hydrogen Gas Generation Using PEM Electrolysis

Both offshore wind and hydrogen generation are increasingly seen as central to global decarbonization. The objective of current research is to investigate the effect of wind turbine height of Vertical Axis Wind Turbine (VAWT) on hydrogen generation. The numerical investigation of VAWT is conducted using techniques of Computational Fluid Dynamics. The VAWT design is developed in Solidworks design software and CFD analysis is conducted using ANSYS CFX software. The CFD analysis conducted on VAWT aided to determine the torque generated from it at 10m/s wind velocity determining the system impacts and ability of electrolyzer technology to accommodate the varying input from wind turbine. The research findings have shown that height of VAWT blade has significant effect on power generation. The power generation from VAWT increases with increase in blade height. The maximum hydrogen mass is generated for 850mm height wind turbine i.e., 2.09Kg. The external wind flow conditions have significant effect on power generation from VAWT and therefore the effect of varying air flow conditions needs to be investigated.

An overview of aerodynamic performance analysis of vertical axis wind turbines

In this paper, an attempt has been made to highlight major developments of vertical axis wind turbines (VAWTs) in the last few decades. The effects of various design parameters such as airfoil, number of blades, solidity, aspect ratio, blade helicity, and overlap ratio have been critically analyzed. Wind energy is the most promising renewable, cost-effective, efficient, and accessible source for both domestic and commercial applications. Horizontal axis wind turbines are highly developed and are being used for medium-to-large scale power projects. VAWT are considered viable options for urban and semi-urban areas. These turbines have several characteristics, such as omnidirectional, power generation in weak and unstable winds, esthetically sound, safety, and low noise. Darrieus turbines with a fixed blade-type have starting problems at low wind speeds. Savonius turbines have good starting capability; however, their power coefficients are lower than other types of VAWT. To overcome the shortcomings of conventional wind turbines, an innovative engineering solution was sought in the design of hybrid VAWT. The analysis revealed that hybrid wind turbines have addressed the deficiencies to an extent; however, the overall performance is still less than that of conventional wind turbines. Several recommendations have been made based on state-of-the-art information from the perspective of future studies and acceptability. It was concluded that vast opportunities for wind turbine applications are available in urban areas; however, further academic research is required on critical aspects such as self-starting at low wind speeds, efficiency, structural reliability, design improvement for aerodynamic performance, and wind resource assessment.

Review of Recent Patents on Vertical-Axis Wind Turbines (VAWTs)

Background: Vertical axis wind turbines (VAWTs) provide an opportunity to take advantage of wind power in a variety of places unfit for traditional horizontal axis wind turbines (HAWT). Despite suffering from a lower efficiency in ideal conditions, other key advantages of vertical axis turbines still give them the ability to outperform traditional wind turbines, especially in urban, low-wind, and turbulent areas around the world. Objective: The purpose of this paper was to conduct a state-of-the-art patent search to analyze recent technological advancements in VAWT designs and deliver an overview of significant patents within this particular field of technology. Methods:: An extensive patent search was performed to determine patents issued in the United States pertaining to the design innovation of VAWTs. The research implements an empirical approach to inspect patent information and a qualitative analysis of the appropriate patents published in VAWT technology. Results: The patent search returned 506 total patents with almost 64% of advancements made in the past ten years, but with limited advancements made within the last 5 years. This article reviews sixteen patent publications since 2010 that highlight the most distinctive VAWT designs. Conclusion: Although progress has stalled over the last 5 years, VAWTs remain a plausible solution for many different environments and non-traditional implementations. While HAWTs have proved to be more efficient, the versatility of reviewed VAWT designs creates a new and untapped potential for wind as a renewable energy source.

Development of a multi rotor floating offshore system based on vertical axis wind turbines

Abstract The upscaling of wind turbines results in fewer units per installed MW reducing infrastructure and maintenance costs of offshore wind farms. Multi rotor systems (MRS), comprising many wind turbine rotors on a single support structure, are potentially a means to maximize the upscaling benefit in achieving larger unit capacities than is feasible or economic with the conventional, 3-bladed horizontal axis wind turbine (HAWT). The MRS has an inherent upscaling advantage which, for a system with many rotors compared to a single rotor, reduces the total weight and cost of rotor-nacelle assemblies by a large factor. An innovative MRS design is presented based on vertical axis wind turbine (VAWT) rotors of the 2-bladed, H-type. Many disadvantages of VAWT design compared to HAWT in a single rotor system (reduced power performance and higher drive train torque, for example) are resolved in the MRS configuration. In addition, reduced component number and simpler components is advantageous for reliability and O&M cost. This MRS concept has many synergies arising from the choice of VAWT rotors. Results comprise a high-level evaluation of system characteristics and the first stage of more detailed investigation of aerodynamics of the high aspect ratio VAWT.

Parked and operating load analysis in the aerodynamic design of multi-megawatt-scale floating vertical-axis wind turbines

Abstract. A good understanding of aerodynamic loading is essential in the design of vertical-axis wind turbines (VAWTs) to properly capture design loads and to estimate the power production. This paper presents a comprehensive aerodynamic design study for a 5 MW Darrieus offshore VAWT in the context of multi-megawatt floating VAWTs. This study systematically analyzes the effect of different, important design variables including the number of blades, aspect ratio and blade tapering in a comprehensive load analysis of both the parked and operating aerodynamic loads including turbine power performance analysis. The number of blades is studied for two- and three-bladed turbines, aspect ratio is defined as ratio of rotor height and rotor diameter and studied for values from 0.5 to 1.5, and blade tapering is applied by means of adding solidity to the blades towards blade root ends, which affects aerodynamic and structural performance. Analyses were carried out using a three-dimensional vortex model named CACTUS (Code for Axial and Cross-flow TUrbine Simulation) to evaluate both instantaneous azimuthal parameters as well as integral parameters, such as loads (thrust force, lateral force and torque loading) and power. Parked loading is a major concern for VAWTs; thus, this work presents a broad evaluation of parked loads for the design variables noted above. This study also illustrates that during the operation of a turbine, lateral loads are on par with thrust loads, which will significantly affect the structural sizing of rotor and platform and mooring components.