Conventional Horizontal Axis Wind Turbines Research Articles

An experimental investigation of a solar chimney integrated with a bladeless wind turbine for sustainable energy harvesting

The current study explores the potential of combining small-scale solar chimney systems with blade-less wind turbines for sustainable energy solutions in Egypt through mathematical modelling, numerical simulation, and experimental work. The integration of a vortex bladeless turbine and a conventional horizontal axis wind turbine in a hybrid energy harvester solar chimney system (VBSCS) was evaluated, as well as the effect of changing the absorber material on improving the system's performance. Shredded rubber improves heat absorption in solar chimney collectors, optimizing energy conversion and providing a sustainable, eco-friendly solution while addressing challenges and cost-effectiveness in implementing this hybrid solution. The mathematical model predicted the highest power at 0.38 W, while the CFD model yielded 0.298 W. Experimental results showed power outputs of 0.18 and 0.25 W for the SCS with concrete and shredded rubber absorbers, respectively. In addition, the VBSCS with a concrete absorber produced 0.29 W. The determined percentage improvement over the SCS with a concrete absorber was 61.1 % for the VBSCS and 38.9 % for the SCS with a black rubber absorber. These findings demonstrate the delicate interplay of design aspects and material choices that influence the performance of both bladeless wind turbines and solar collector systems.

Vertical Axis Wind Turbine Layout Optimization

Vertical Axis Wind Turbines (VAWTs) are not mature enough yet for offshore wind farms, but they offer benefits compared to conventional Horizontal Axis Wind Turbines (HAWTs). Higher power densities, reduced wakes, lower center of mass, and different power and thrust curves make VAWTs an interesting option to complement existing wind farms. The optimization of wind farm layouts—finding the optimal positions of wind turbines in a park—has proven crucial to extract more energy from conventional wind farms. In this study, we build an optimizer for VAWTs that can consider arbitrarily shaped layouts as well as obstacles in the area. We adapt a recent model for the wakes of VAWTs considering a Troposkien design. We can then model and optimize a large VAWT park in a real wind scenario and assess for the first time its performance operating Troposkien VAWTs. In addition, we present a novel model for wind farm optimization that considers the clockwise and counterclockwise rotation of turbines. This optimization exploits the asymmetric wakes of VAWTs, thus increasing the total energy production. We benchmark our optimization on realistic instances and compare VAWTs and HAWTs wind farm layouts, showing that VAWTs can achieve higher density and power production than HAWTs in the same area. Finally, the wake loss reduction is compared to the literature.

Aerodynamic Performance and Wake Characteristics Analysis of Archimedes Spiral Wind Turbine Rotors with Different Blade Angle

Continuous improvement of wind turbines represent an effective way of achieving green energy and reducing dependence on fossil fuel. Conventional lift-type horizontal axis wind turbines, which are widely used, are designed to run under high wind speed to obtain a high efficiency. Aiming to use the low-speed wind in urban areas, a novel turbine, which is called the Archimedes Spiral Wind Turbine (abbreviated as ASWT), was recently proposed for low-speed wind applications. In the current work, a numerical simulation on the five ASWT rotors with different blade angles was carried out, which were performed to predict the detailed aerodynamic performance and wake characteristics. The results show that the ASWT rotor with a large blade angle has a wider operating tip speed ratio range and a higher tip speed ratio point of maximum power coefficient within a certain range, and yet the ASWT rotor with the larger blade angle has a higher thrust coefficient. Additionally, the ASWT rotor with a large blade angle usually has a large power coefficient and thrust coefficient fluctuation amplitude. On the other hand, the ASWT rotor with a small blade angle permits the undisturbed free stream to pass through the rotor blades more easily than that with a large blade angle. This causes a stronger blockage effect for the ASWT rotor with a large blade angle. Moreover, the blade angle also has a great effect on the shape of the vortex structure. The blade tip vortex of the fixed-angle ASWT rotors is more stable than those of the variable-angle ASWT rotors. The hub vortex of the ASWT rotors with a large blade angle is stronger than those with a small blade angle. Meanwhile, the wake recovery for ASWT rotors with a small blade angle is evidently lower than those with a large blade angle.

Optimization of the Eolic Cell to improve the wind velocity augmentation effect through the metamodel of optimal prognosis

• Wind velocity augmentation effect is sensitive to the Eolic Cell’s internal shape. • A narrow region from the workspace circumscribes all individual optimal profiles. • Averaged optimal profile application does not compromise the augmentation effect. • Averaged optimal profile becomes suitable for distributed generation purposes. • Eolic Cell presents a material potential to become a highly efficient energy system. Currently, most of all wind energy installed capacity in the world is located in wind farms and the reason behind that is related to the fact that conventional horizontal-axis wind turbines are highly efficient only at large scales, thus posing a concentration problem to the progress of energy transition and wind distributed generation. To address that problem, the present paper explores the utilization of a novel modular augmented wind turbine, based on Eolic Cells, to increase wind speed in order to harvest more power from the same wind resource as means to decentralize wind-energy generation around a wider range of wind sites suitable for distributed generation. The Eolic Cell’s wind velocity augmentation effect was simulated numerically by using computational fluid dynamics and optimized through a metamodel of optimal prognosis, which geometries were parameterized by using Bezier Curves and calibrated against field experiments. Results confirm the ability of this new device to substantially increase wind velocity and potentially achieve high levels of efficiency at a distributed-generation scale. The present work is the first release of a broader and more comprehensive research project on Eolic Cells as an alternative wind energy system for distributed generation. The whole research project involves studies on power augmentation curves, multivariable prognosis surfaces, optimum spacing layout, peripherally-supported wind turbine, power curves, prototype testing, as well as exhaustive wind-tunnel and field experiments, which are expected to be included in future releases of the present research project.

Electricity Generation by Vertical Axis Turbine

Abstract: Wind energy is the kinetic energy associated with movement of large masses of air. These motions result from uneven heating of atmosphere by sun creating temperature, density, pressure differences. It is an indirect form of solar energy The device used to convert kinetic energy of wind into electrical power is called a wind turbine. Vertical Axis wind power generators, represent a very promising future for wind power generation. In present study an attempt is made to utilize at low velocity wind below 4m/s for useful power generation using magnetic levitation for vertical axis wind turbine (VAWT) termed as Maglev turbine. A single large Maglev turbine can give output more than conventional horizontal axis wind turbine (HAWT). The rotor that is designed to harness enough air to rotate the shaft at low and high wind speeds while keeping the center of mass closer to the base of yielding stability due to Maglev effect. The efficiency of turbine is increased by replacing the conventional bearings by magnets in repulsion; the magnetic levitation helps the turbine to spin at much faster rate as it eliminates the stresses on the shaft of turbine. The major components are placed at the ground level which ensures the safety of turbine.

Optimisation of H-Darrieus VAWT Solidity for Energy Extraction in Cooling Tower Exhaust Systems

The technologies surrounding renewable energy have been receiving surmountable attention to producing clean energy and reducing the dependency on depleting fossil fuel sources. In this context, research investigations on vertical axis wind turbines (VAWT) in free stream flow condition has been extensively conducted to improve the energy extraction efficiency from the wind. VAWTs are particularly advantageous in locations not suitable for conventional horizontal axis wind turbines (HAWT). However, the applications of VAWTs are still limited due to their lower performances compared to their counterparts. Furthermore, the wind energy extraction problem is more prominent in urban areas with unpredictable and inadequate wind speed conditions. The present study focuses on an alternative way to harness wind energy from unnatural sources such as cooling tower exhaust systems with the reliable and consistent exhaust air. A three-dimensional numerical study has been conducted to investigate the performance of a 3-bladed H-Darrieus wind turbine (HDWT) using S-1046 airfoils of four different solidities under accelerated wind conditions of a cooling tower. The HDWT model is positioned at the cooling tower outlet, where it rotates using sliding mesh to measure the power output. Shear stress transport (SST) k- turbulence model solver was used to solve the implicit unsteady Reynolds-Averaged Navier-Stokes equations. It is observed that the higher solidity HDWT reached peak power coefficient at a lower tip speed ratio (TSR). In contrast, lower solidity HDWT achieved peak power coefficient at higher TSR. The higher solidity 0.375 and 0.450 produced a maximum power coefficient of 0.233 at TSR of 2.0.

Measurement and analysis for the improvement of efficiency and power of Savonius vertical axis wind turbines without dimples and fins

Energy effective approaches to improve the extraction of work from different sources of renewable energy are still appreciated in this energy starved world. Wind energy is one such widely used source. Wind energy is one of the world's most rapidly expanding electricity industries and most exciting alternative energy sources. A. Crespo, J. Hernandez, and S. Frandsen, “Survey of modelling methods for wind turbine wakes and wind farms Wind turbine technology is a method for converting wind kinetic energy into electrical energy. Efforts have been made in recent years to increase the capacity and reliability of standard Savonius VAWTs, which are not only easy to create but can also be used as a renewable energy source to meet the needs of rural areas with low power consumption. A.J. Alexander, B.P. Holownia Wind tunnel tests on a Savonius rotor; Journal of Industrial Aerodynamics In this present research paper, we analysis for the improvement of Efficiency and the power of the Savonius type wind turbine without using dimples on their blades and fins for more pressure generation Akwa, J. V., Vielmo et al., Review on the Performance of Savonius Wind Turbines“, Renewable and Sustainable Energy. the Savonius vertical axis wind turbine could be a safer alternative because it can also work in low wind conditions The aim of this model is to demonstrate its performance in varying wind conditions as opposed to the conventional horizontal axis wind turbine, and to contribute to its steady increasing popularity as a reliable source of power generation in the near future.

Vertical axis wind turbine operation in icing conditions: A review study

Vertical Axis Wind Turbine (VAWT) can be a promising solution for electricity production in remote ice prone territories of high north, where good wind resources are available, but icing is a challenge that can affect its optimum operation. A lot of research has been made to study the icing effects on the conventional horizontal axis wind turbines, but the literature about vertical axis wind turbines operating in icing conditions is still scarce, despite the importance of this topic. This paper presents a review study about existing knowledge of VAWT operation in icing condition. Focus has been made in better understanding of ice accretion physics along VAWT blades and methods to detect and mitigate icing effects.

CFD Comparative Study on Bended and 2D Airfoils on HAWT Performance

The design of a conventional horizontal axis wind turbine (HAWT) is based on the aerodynamic characteristics of a two-dimensional (2D) airfoil. The rotational motion and the consequent aerodynamic effects, of HAWT’s rotor, do not guarantee an optimal design point that matches the 2D airfoil characteristics. The present work studies the diversion of the flow due to the spanwise velocity component in a rotating reference frame. It suggests that a slight deviation in the flow away from the chordwise direction could alternate the characteristics of the airfoil profile. A bended profile with a circular arc was extracted from a baseline rotating blade, flattened, and modelled against the 2D S826 airfoil. The results show a substantial discrepancy in the airfoil characteristics which could influence the turbine efficiency. Therefore, it suggests using a pre-bended airfoil (3D) while modeling the blade, so the circular section will match the correct airfoil coordinates. The proposed bended-profile version was modeled against the baseline blade. This novel blade shows an augmentation in the power coefficient up to 5.4% starting from the design point to high tip speed ratios (TSR) and low wind speeds.

Innovative design method and experimental investigation of a small-scale and very low tip-speed ratio wind turbine

Small horizontal axis wind turbines operating at low wind speeds face the issue of low performance compared to large wind turbines. A high amount of torque is required to start producing power at low wind speed to overtake friction of mechanical parts. A low design tip-speed ratio (λ) is suitable for low power applications. The relevance of the classical blade-element/ momentum theory, traditionally used for the design of large wind turbines operating at high tip-speed ratio, is controversial at low tip-speed ratio. This paper presents a new design methodology for a 300 mm horizontal axis wind turbine operating at very low tip-speed ratio. Chord and blade angle distributions were computed by applying the Euler’s turbomachinery theorem. The new wind turbine has multiple fan-type blades and a high solidity. The rotor was tested in wind tunnel. The power and torque coefficients have been measured, and the velocities in the wake have been explored by stereoscopic particle image velocimetry. The results are compared to a conventional 3-bladed horizontal axis wind turbine operating at higher tip-speed ratio λ=3. The new wind turbine achieves a maximum power coefficient of 0.31 for λ=1. The conventional wind turbine achieves similar performance. At low tip-speed ratio, the torque coefficient (Cτ) is higher for the new wind turbine than for the conventional one and decreases linearly with the tip-speed ratio. The high magnitude of torque at low tip-speed ratio allows it to have lower instantaneous cut-in wind speed (2.4 m.s−1) than the conventional wind turbine (7.9 m.s−1). The order of magnitude of the axial and tangential velocities in the near wake are closed to the design requirements. The current method could still be improved in order to better predict the profiles. The analysis of the wake shows that the new wind turbine induces a highly stable and rotating wake, with lower wake expansion and deceleration than the conventional one. This could be useful to drive a contra-rotating rotor.

Analysis of Magnetic Levitated Savonius Wind Turbine

Vertical axis wind turbine is one of the types of savonius wind turbine; VAWT generates huge twisting moment when running under lower speed by wind. Savonius wind turbine is the self-starting turbine; it uses magnetic levitation principle to get high rotational speed for the Generator. Magnetic Levitation is the phenomenon in which anything can freely suspend in the air without any support with opposed of gravitational energy. This magnetic levitation occurred due to the repulsion between the two symmetrical poles. The strong levitation is occurred with the use of permanent magnets. This type of model is to show its greater efficiency in varying wind conditions as compared to the conventional horizontal axis wind turbine and contribute to steady growing popularity for the purpose of increased utilization in the recent future as a reliable source of power generation.

Numerical analysis of the effect of the mutual interaction between closely separated variable pitch vertical axis wind turbines

Recent researches have proven that mutual interaction between vertical axis wind turbines (VAWTs) results in enhancement in the average power coefficient. Efficient VAWT clusters have been created to provide wind farms having higher power densities compared to conventional horizontal vertical axis wind turbine farms. The created clusters adopted fixed pitch VAWTs in studying the mutual interaction in close vicinity. This paper extends the investigation of the mutual effect between variable pitch VAWTs in closely oriented turbine clusters. A numerical study is performed using commercial Fluent ANSYS code in order to study the effect of gap distances, phase shifts, and oblique angles for co-rotating and counter-rotating arrangements of two variable pitch VAWTs. The results showed improvement in the performance of two turbine clusters up to 26% compared to isolated turbines. Three turbine clusters are also tested numerically based on the results of the two turbine clusters. The created three turbine cluster represents a basic unit to construct a more efficient wind farm. The results of the developed three turbine cluster showed an increase in the average power coefficient by 38% higher than that of isolated turbines.

Feasibility study of new generation of wind turbine (INVELOX), is it competitive with the Conventional Horizontal Axis Wind Turbine?

Wind energy is one of the most interesting and cost-effective renewable energies. In this article, a comparison between two wind turbine technologies (Conventional Horizontal Axis Wind Turbine (CHAWT) and a new generation of wind turbine (INVELOX)) is made. They are simulated using CFD. A sensitive analysis into the geometrical parameters is performed. Then technical and economic analyses are done in five cities in Iran. Results show INVELOX generates 18%–235% more power than conventional one. However, the initial cost of INVELOX is nearly 534%–576% higher than the CHAWT. So, the proposed form of wind turbine cannot be economically feasible. Also, it is concluded that INVELOX technology is suitable for the cities with the low average wind speed such as Binaloud. It seems that INVELOX is more suitable for critical condition in which more energy density is needed and the economic aspect is not important.

Numerical Analysis of Exhaust Air Energy Extractor for Cooling Tower Applications

Over the years, the need of renewable energy has been accelerated to minimise the reliance on using the fast depleting fossil fuel. Research on wind turbines to harness wind power is widely increasing especially with the progression of vertical axis wind turbines (VAWT) for the locations, where conventional horizontal axis wind turbines are not effective. The ability to provide renewable energy by generating efficient power is vital in combatting climate change due to increase in global energy demand thus, leading to this present study of extracting wind energy from a cooling tower. In this paper, a three dimensional numerical investigation has been conducted on the straight bladed Darrieus type VAWTs with S1046 airfoils. The implicit unsteady Reynolds-Averaged Navier-Stokes equations are solved using shear stress transport k-? turbulent model. The VAWT model is placed at the outlet of the cooling tower to calculate power output with an aspect ratio of 0.88. The results show that a maximum power coefficient of 0.36 is obtained at a tip speed ratio of 3.0.

Effect of aspect ratio on vertical-axis wind turbine wakes

Variability of the rotor aspect ratio is one of the inherent characteristics of vertical-axis wind turbines (VAWTs) which differentiates them especially from the more conventional horizontal-axis wind turbines. In this study, we intend to investigate the effect of rotor aspect ratio on VAWT wakes. In particular, we aim to find out whether a common behaviour exists in the mean flow field of such wakes. In order to do so, we first design and perform a set of numerical experiments (using our already validated large-eddy simulation framework) to obtain the mean flow field of the wakes of three VAWTs of different aspect ratio (2, 1 and ) and the same thrust coefficient ( ). After observing the obvious differences in these three wakes, by using the classical momentum integral and the concept of momentum diameter, we come up with an appropriate normalization length scale , where is the rotor diameter and is the rotor height. By normalizing the lengths (both streamwise and lateral) involved in the mean velocity profiles by , we obtain a remarkable collapse of the wake profiles for the three aspect ratios. As a corollary, cross-sections of wakes of turbines with different aspect ratios eventually converge to a circular shape – not an elliptical one, for example, as one might presume intuitively. This result influences the modelling of VAWT far wakes and, in turn, has implications on the optimal configuration of VAWT farms.

Numerical and Experimental Investigations on a Dimpled Savonius Vertical Axis Wind Turbine

This research deals with the design and fabrication of novel designs as a mean to harness wind energy using a ‘Savonius’ Turbine. It is generally employed to harvest the low to very low wind speed potentials. They can particularly be of high use in the regions where the wind speeds are not high enough for installing conventional horizontal axis wind turbines. The paper introduces a novel concept of testing a Savonius wind turbine with dimple structures on its blades and investigating its effect on the turbine’s efficiency. The study also deals with the experimental validation of the effect of using a converging ducted structure with a single stage and double stage configurations of Savonius wind turbine, apart from comparing the turbine’s performance with and without endplates. The results of the study proves that power coefficient increases with the addition of dimple structures on the blades and it can be further augmented by using a ducted structure with the Savonius turbine.

Building integration of stator‐augmented PowerWindow, a linear cascade wind turbine

AbstractThis study investigates power generation capacity of stator‐augmented PowerWindow, a linear cascade wind turbine, when installed in through‐building openings of a tall building. By employing a new approach, referred to as equivalent momentum sink method, the flow characteristics of the ducted flow, such as its pressure, velocity, and turbulence intensity are predicted when subjected to different wind directions in presence of a wind turbine. This study shows that a properly designed layout maintains the velocity in the through‐building openings for a wide range of wind directions and enhances the power generation by 50%‐80% in comparison with the free‐stream wind turbine installed at the same elevation. This study also compares the power generation of stator‐augmented PowerWindow with a conventional horizontal axis wind turbine, Ampair 300, installed in the same through‐building openings. The results show that the power generation of the ducted stator‐augmented PowerWindow is close to that of the ducted Ampair 300 in certain wind directions. However, it can also effectively generate power at those wind directions that the ducted Ampair 300 is unable to operate. The analysis shows that this advantage significantly increases the annual power generation probability of the building‐integrated stator‐augmented PowerWindow. As a case study, it is shown that by embedding four through‐building openings integrated with stator‐augmented PowerWindow in a tall building in Sydney area, a portion (0.55‐8.07 KW) of the electricity consumption of the building facilities can be supplied 72% of times.

Design, Fabrication and Performance Analysis of Loopwing Horizontal Axis Wind Turbine

This research presents the design, fabrication and performance analysis of loopwing horizontal axis wind turbine. Among the many types of wind turbine, most of them failed in efficiency because of the higher rotating speed required in other conventionalhorizontal axis wind turbine. Another vertical axis wind turbine suffers unbalance torque between the right and left side whichcauses vibration. Loopwing horizontal axis wind turbine is operated at low rotating speed without reducing energy efficiency.There is no vortex discharge and noise because loopwing horizontal axis wind turbine has strip ribbons as its blade tip portionends in a loop shape. Loopwing horizontal axis wind turbine blade is designed by the using of basic design formula such asangular momentum theory, blade element theory. The NASA SC(2)-0402 is chosen as the loopwing horizontal axis wind turbineblade profile by comparing it with a similar airfoil shape from the results of Profili Software. The model of loopwing horizontalaxis wind turbine is drawn by using Solidworks 2018. Performance testing is carried out on the roof of Main-Building atMandalay Technological University. The wind turbine hub is placed 14.6 m above the ground. The material of loop type bladewind turbine is stainless steel. The performance analysis of loopwing horizontal axis wind turbine is emphasized in this research.This loop type blade wind turbine can be started wind speed at 1.5m/s and cut-out wind speed at 12m/s. Electrical power outputcan be produced by about 100 W by the following horizontal axis wind generator at rated wind speed 6m/s. Rotor diameter is1.5m and the no. of the blade is three and the tip speed ratio is 5

Oscillating-wing unit for power generation

This paper describes an exploratory study of a nonconventional wind power converter with a pair of oscillating wings, which is called an oscillating-wing unit. The working principles of the oscillating-wing unit are described, including the aerodynamic models, kinematical, and dynamical models. The performance of the oscillating-wing unit is evaluated through computational simulations and the power scaling in comparison with conventional horizontal-axis wind turbines. Then, a model oscillating-wing unit is designed, built, and tested in a wind tunnel to examine the feasibility of the oscillating-wing unit in extraction of the wind energy in comparison with the theoretical analysis. The theoretical analysis and experimental data indicate that the oscillating-wing unit has the power efficiency comparable to the conventional horizontal axis wind turbine and it can operate at low wind speeds.

Building a low cost wind turbine in highways for rural house electricity demand

The main aim of this work is to design, fabricate, and test a wind turbine for power generation applications in rural areas. Vertical Axis Wind Turbines were selected to harness the energy from wind through the drag forces induced due to vehicular movements. Various parameters were analyzed for the design of a low‐cost wind turbine. A Savonius blade was selected for the design, which could be accommodated on the median of the highways. By using recycled materials, a low‐cost wind turbine was fabricated at a cost of $117.5 approximately. The wind turbine was placed on the houses and on the highway medians to test the power output at various operating conditions. Average electricity consumption at selected rural houses were calculated. The calculated average electricity demand during power cuts in the selected rural houses was around 0.2–0.6 kWh/day. Average generated electricity from the turbine at highways was observed to be around 0.67 kWh/day. The Levelized cost of electricity (LCOE) of the generated electricity from the proposed SWT on highways is around $0.04/kWh. The LCOE of the proposed design is relatively cheaper when compared with the conventional horizontal axis wind turbines. The energy demand during power cuts was met completely when the SWT was placed on the highways. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 278–285, 2019