Wind tunnel and numerical study of multi-storey vertical axis wind turbines with different configurations

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abhijeet M. Malge ◽  
Prashant Maruti Pawar
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Power ◽  
Wind Turbines ◽  
Numerical Study ◽  
Research Work ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Content Type ◽  
Vertical Axis Wind Turbines

Purpose Three different configurations of vertical axis wind turbines (VAWT) were fabricated by changing the storey height and their orientations. The purpose of this study is to find the effect of storey height and orientation on the performance of wind turbines. The multistory VAWT has three storeys. The first configuration had increased middle storey height, with 0–90-0 orientation of blades. Wherein the second turbine had equal storey heights. The third configuration had increased middle storey height with 0–120-240 orientation of blades. The blades were tested numerically and experimentally. Design/methodology/approach In this research work, prototypes of innovative multistory VAWT were built with different configurations and orientations. Three configurations of three-storey VAWT were fabricated by varying the height of storey of turbines. The orientations were made by keeping the storeys orthogonal to each other. Multistory VAWT was tested numerically and experimentally. ANSYS Fluent was used for computational fluid dynamic analysis of VAWT. K-epsilon model was used for numerical analysis of wind turbine. Experimentation was carried out in a wind tunnel for different tip speed ratios (TSR). Findings The three configurations of innovative multistory VAWT were tested numerically and experimentally for different TSR. It has been found that the VAWT with equal storey height had a better performance as compared to the other two configurations with increased middle storey height. The power coefficient of equal storey height VAWT was about 22%, wherein the power coefficient of turbines with reduced upper and lower storey height was between 5%–8% Research limitations/implications The research work of multi-storey VAWT is very novel and original. The findings of the research will contribute to the existing work done in the field of VAWT. This will help other researchers to have insight into the development of multistory VAWT. The effect of storey height and configuration of multi-storey VAWT is studied numerically and experimentally, which concludes that the performance of equal storey is superior as compared to other configurations. Practical implications The multi-storey concept of VAWT was developed to counter the problem of wind direction. The blades of each storey were arranged orthogonal to each other. This helped to harness wind power irrespective of the direction of the wind. This will make the VAWT more sustainable and financially viable for domestic use. Social implications The turbines are specially designed for remotely located housed in rural areas where the power grid is not yet reached. Users can install the turbine on their rooftop and harness wind power of 100 W capacity. This will help them to make their life easy. Originality/value This research work is very original and first of a kind. The multistory concept of the wind turbine was checked for the effect of storey height and orientations of blades on its performance. Different configurations and orientations of the vertical axis were designed and developed for the first time.

scholarly journals An experimental study of the optimal design parameters of a wind power tower used to improve the performance of vertical axis wind turbines

2018 ◽  
Vol 10 (9) ◽  
pp. 168781401879954
Author(s):  
Soo-Yong Cho ◽  
Sang-Kyu Choi ◽  
Jin-Gyun Kim ◽  
Chong-Hyun Cho
Keyword(s):  
Experimental Study ◽  
Optimal Design ◽  
Wind Turbine ◽  
Wind Power ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Design Parameters ◽  
Vertical Axis Wind Turbine ◽  
Vertical Axis Wind Turbines

In order to augment the performance of vertical axis wind turbines, wind power towers have been used because they increase the frontal area. Typically, the wind power tower is installed as a circular column around a vertical axis wind turbine because the vertical axis wind turbine should be operated in an omnidirectional wind. As a result, the performance of the vertical axis wind turbine depends on the design parameters of the wind power tower. An experimental study was conducted in a wind tunnel to investigate the optimal design parameters of the wind power tower. Three different sizes of guide walls were applied to test with various wind power tower design parameters. The tested vertical axis wind turbine consisted of three blades of the NACA0018 profile and its solidity was 0.5. In order to simulate the operation in omnidirectional winds, the wind power tower was fabricated to be rotated. The performance of the vertical axis wind turbine was severely varied depending on the azimuthal location of the wind power tower. Comparison of the performance of the vertical axis wind turbine was performed based on the power coefficient obtained by averaging for the one periodic azimuth angle. The optimal design parameters were estimated using the results obtained under equal experimental conditions. When the non-dimensional inner gap was 0.3, the performance of the vertical axis wind turbine was better than any other gaps.

scholarly journals Numerical Investigations of the Effects of the Rotating Shaft and Optimization of Urban Vertical Axis Wind Turbines

Energies ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1870 ◽  
Author(s):  
Lidong Zhang ◽  
Kaiqi Zhu ◽  
Junwei Zhong ◽  
Ling Zhang ◽  
Tieliu Jiang ◽  
...  
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Suction Side ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Small Scale ◽  
Physical Parameters ◽  
Rotating Shaft ◽  
Vertical Axis Wind Turbines ◽  
Negative Effect

The central shaft is an important and indispensable part of a small scale urban vertical axis wind turbines (VAWTs). Normally, it is often operated at the same angular velocity as the wind turbine. The shedding vortices released by the rotating shaft have a negative effect on the blades passing the wake of the wind shaft. The objective of this study is to explore the influence of the wake of rotating shaft on the performance of the VAWT under different operational and physical parameters. The results show that when the ratio of the shaft diameter to the wind turbine diameter (α) is 9%, the power loss of the wind turbine in one revolution increases from 0% to 25% relative to that of no-shaft wind turbine (this is a numerical experiment for which the shaft of the VAWT is removed in order to study the interactions between the shaft and blade). When the downstream blades pass through the wake of the shaft, the pressure gradient of the suction side and pressure side is changed, and an adverse effect is also exerted on the lift generation in the blades. In addition, α = 5% is a critical value for the rotating shaft wind turbine (the lift-drag ratio trend of the shaft changes differently). In order to figure out the impacts of four factors; namely, tip speed ratios (TSRs), α, turbulence intensity (TI), and the relative surface roughness value (ks/ds) on the performance of a VAWT system, the Taguchi method is employed in this study. The influence strength order of these factors is featured by TSRs > ks/ds > α > TI. Furthermore, within the range we have analyzed in this study, the optimal power coefficient (Cp) occurred under the condition of TSR = 4, α = 5%, ks/ds = 1 × 10−2, and TI = 8%.

Power performance enhancement of vertical axis wind turbines by a novel gurney flap design

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Milad Mousavi ◽  
Mehran Masdari ◽  
Mojtaba Tahani
Keyword(s):  
Wind Turbines ◽  
Vertical Axis ◽  
Dynamics Simulation ◽  
Power Coefficient ◽  
Lower Amount ◽  
Speed Ratio ◽  
Power Performance ◽  
Content Type ◽  
Vertical Axis Wind Turbines ◽  
Gurney Flap

Purpose Nowadays flaps and winglets are one of the main mechanisms to increase airfoil efficiency. This study aims to investigate the power performance of vertical axis wind turbines (VAWT) that are equipped with diverse gurney flaps. This study could play a crucial role in the design of the VAWT in the future. Design/methodology/approach In this paper, the two-dimensional computational fluid dynamics simulation is used. The second-order finite volume method is used for the discretization of the governing equations. Findings The results show that the gurney flap enhances the power coefficient at the low range of tip speed ratio (TSR). When an angled and standard gurney flap case has the same aerodynamic performance, an angled gurney flap case has a lower hinge moment on the junction of airfoil and gurney flap which shows the structural excellence of this case. In all gurney flap cases, the power coefficient increases by an average of 20% at the TSR range of 0.6 to 1.8. The gurney flap cases do not perform well at the high TSR range and the results show a lower amount of power coefficient compare to the clean airfoil. Originality/value The angled gurney flap which has the structural advantage and is deployed to the pressure side of the airfoil improves the efficiency of VAWT at the low and medium range of TSR. This study recommends using a controllable gurney flap which could be deployed at a certain amount of TSR.

Wind Tunnel Experiment on the Aerodynamic Interaction Between Vertical Axis Wind Turbine Pair

2021 ◽  
Author(s):  
Hao Su ◽  
Haoran Meng ◽  
Jia Guo ◽  
Timing Qu ◽  
Liping Lei
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Vertical Axis Wind Turbine ◽  
Power Performance ◽  
Array Configuration ◽  
Aerodynamic Interaction ◽  
Positive Effect

Abstract Wind energy has attracted worldwide attention as a pollution-free and widely distributed renewable energy source. Increasing the power density by optimizing the arrangement of wind turbines has been a popular field of research in recent years. In the present work, a systematic study on the influence of array configuration on vertical axis wind turbines is made through wind tunnel experiments. Firstly, the power performance of an isolated vertical axis wind turbine at different tip speed ratios is tested as a benchmark of comparison. Multiple situations of two-turbine configurations are then tested and the results are compared with the isolated wind turbine. The power coefficient of the turbine pair increases by 34% when the turbines are 2.4 rotor diameters apart and rotate in the same direction. In the counter-rotating co-leeward case, it is demonstrated that the turbine pairs will have a positive effect on each other when they are separated by 2.1 rotor diameters to 2.4 rotor diameters. The lateral spacing between the counter-rotating co-windward turbine pair should be greater than 1.5 rotor diameters to avoid turbulence interference between the rotors.

Aerodynamic Measurements on a Vertical Axis Wind Turbine in a Large Scale Wind Tunnel

2010 ◽  
Author(s):  
L. Battisti ◽  
L. Zanne ◽  
S. Dell’Anna ◽  
V. Dossena ◽  
B. Paradiso ◽  
...  
Keyword(s):  
Wind Tunnel ◽  
Flow Field ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Aerodynamic Optimization ◽  
Vertical Axis Wind Turbines

This paper presents the first results of a wide experimental investigation on the aerodynamics of a vertical axis wind turbine. Vertical axis wind turbines have recently received particular attention, as interesting alternative for small and micro generation applications. However, the complex fluid dynamic mechanisms occurring in these machines make the aerodynamic optimization of the rotors still an open issue and detailed experimental analyses are now highly recommended to convert improved flow field comprehensions into novel design techniques. The experiments were performed in the large-scale wind tunnel of the Politecnico di Milano (Italy), where real-scale wind turbines for micro generation can be tested in full similarity conditions. Open and closed wind tunnel configurations are considered in such a way to quantify the influence of model blockage for several operational conditions. Integral torque and thrust measurements, as well as detailed aerodynamic measurements were applied to characterize the 3D flow field downstream of the turbine. The local unsteady flow field and the streamwise turbulent component, both resolved in phase with the rotor position, were derived by hot wire measurements. The paper critically analyses the models and the correlations usually applied to correct the wind tunnel blockage effects. Results evidence that the presently available theoretical correction models does not provide accurate estimates of the blockage effect in the case of vertical axis wind turbines. The tip aerodynamic phenomena, in particular, seem to play a key role for the prediction of the turbine performance; large-scale unsteadiness is observed in that region and a simple flow model is used to explain the different flow features with respect to horizontal axis wind turbines.

scholarly journals Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5564
Author(s):  
Rosario Lanzafame ◽  
Stefano Mauro ◽  
Michele Messina ◽  
Sebastian Brusca
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Fluid Dynamic ◽  
Vertical Axis ◽  
Operating Conditions ◽  
Time Step ◽  
Vertical Axis Wind Turbines ◽  
2D Model

The simulation of very small vertical axis wind turbines is often a complex task due to the very low Reynolds number effects and the strong unsteadiness related to the rotor operation. Moreover, the high boundary layer instabilities, which affect these turbines, strongly limits their efficiency compared to micro horizontal axis wind turbines. However, as the scientific interest toward micro wind turbine power generation is growing for powering small stand-alone devices, Vertical Axis Wind Turbines (VAWTs)might be very suitable for this kind of application as well. Furthermore, micro wind turbines are widely used for wind tunnel testing, as the wind tunnel dimensions are usually quite limited. In order to obtain a better comprehension of the fluid dynamics of such micro rotors, in the present paper the authors demonstrate how to develop an accurate CFD 2D model of a micro H-Darrieus wind turbine, inherently characterized by highly unstable operating conditions. The rotor was tested in the subsonic wind tunnel, owned by the University of Catania, in order to obtain the experimental validation of the numerical model. The modeling methodology was developed by means of an accurate grid and time step sensitivity study and by comparing different approaches for the turbulence closure. The hybrid LES/RANS Delayed Detached Eddy Simulation, coupled to a transition model, demonstrated superior accuracy compared to the most advanced unsteady RANS models. Therefore, the CFD 2D model developed in this work allowed for a thorough insight into the unstable fluid dynamic operating conditions of micro VAWTs, leading the way for the performance improvement of such rotors.

scholarly journals Application of Simultaneous Symmetric and Cambered Airfoils in Novel Vertical Axis Wind Turbines

2021 ◽  
Vol 11 (17) ◽  
pp. 8011
Author(s):  
Sajad Maleki Dastjerdi ◽  
Kobra Gharali ◽  
Armughan Al-Haq ◽  
Jatin Nathwani
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Vertical Axis ◽  
Dynamic Stall ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Vertical Axis Wind Turbines ◽  
Good Potential ◽  
Computational Fluid Dynamics Cfd ◽  
Naca0018 Airfoil

Two novel four-blade H-darrieus vertical axis wind turbines (VAWTs) have been proposed for enhancing self-start capability and power production. The two different airfoil types for the turbines are assessed: a cambered S815 airfoil and a symmetric NACA0018 airfoil. For the first novel wind turbine configuration, the Non-Similar Airfoils 1 (NSA-1), two NACA0018 airfoils, and two S815 airfoils are opposite to each other. For the second novel configuration (NSA-2), each of the S815 airfoils is opposite to one NACA0018 airfoil. Using computational fluid dynamics (CFD) simulations, static and dynamic conditions are evaluated to establish self-starting ability and the power coefficient, respectively. Dynamic stall investigation of each blade of the turbines shows that NACA0018 under dynamic stall impacts the turbine’s performance and the onset of dynamic stall decreases the power coefficient of the turbine significantly. The results show that NSA-2 followed by NSA-1 has good potential to improve the self-starting ability (13.3%) compared to the turbine with symmetric airfoils called HT-NACA0018. In terms of self-starting ability, NSA-2 not only can perform in about 66.67% of 360° similar to the wind turbine with non-symmetric airfoils (named HT-S815) but the power coefficient of NSA-2 at the design tip speed ratio of 2.5 is also 4.5 times more than the power coefficient of HT-S815; the power coefficient difference between HT-NACA0018 and HT-S815 (=0.231) is decreased significantly when HT-S815 is replaced by NSA-2 (=0.076). These novel wind turbines are also simple.

A Study of the Twisted Sweeney-Type Wind Turbine

2003 ◽  
Vol 27 (4) ◽  
pp. 317-321 ◽  
Author(s):  
Yasuyuki Nemoto ◽  
Ayumu Anzai ◽  
Izumi Ushiyama
Keyword(s):  
Wind Tunnel ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Lift Force ◽  
Experimental Testing ◽  
Vertical Axis ◽  
Late Professor ◽  
Princeton University ◽  
Vertical Axis Wind Turbines

The late professor Thomas E. Sweeney of Princeton University proposed the concept of vertical-axis wind turbines driven by drag/lift force in 1973. The authors fabricated Twisted-Sweeney type wind turbines, based on the Sweeney type wind turbine, to improve the performance and to enhance its external appearances. From experimental testing of this wind turbine in a wind tunnel, the following conclusions were deduced.

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

2020 ◽  
pp. 0309524X2097167
Author(s):  
Mohammed Shaheen
Keyword(s):  
Wind Turbines ◽  
Numerical Study ◽  
Average Power ◽  
Mutual Effect ◽  
Vertical Axis ◽  
Mutual Interaction ◽  
Power Coefficient ◽  
Basic Unit ◽  
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.

Torque and Power Coefficients of a Vertical Axis Wind Turbine With Optimal Pitch Control

2010 ◽  
Author(s):  
Jim Shih-Jiun Chen ◽  
Zhi Chen ◽  
Saroj Biswas ◽  
Jiun-Jih Miau ◽  
Cheng-Han Hsieh
Keyword(s):  
Low Power ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Tangential Force ◽  
Vertical Axis ◽  
Power Coefficient ◽  
Small Scale ◽  
Manufacturing Cost ◽  
Pitch Control ◽  
Vertical Axis Wind Turbines

Vertical axis wind turbines (VAWT) have been valued in recent years for their low manufacturing cost, structural simplicity and convenience of applications in urban settings. Despite their advantages, VAWTs have several drawbacks including low power coefficient, poor self-starting ability, negative torque and the associated cyclic stress at certain azimuth angles. Using pitch control ideas, our research is aimed at solving the above problems. In this study, a small-scale Giromill VAWT using three NACA-0015 airfoils with a cord length of 0.09 m and a wind turbine radius of 0.6 m is investigated. During each rotation, the angle of attack depends on the wind velocity, angular velocity and current azimuth angle for each turbine blade. Negative torques at certain angles are attributed to the inherent unsteady aerodynamic behavior at high angles of attack. Without optimal pitch control, the Double-Multiple Streamtube (DMS) model predicts negative torques at certain azimuth angles and very low power coefficients for tip speed ratios below 2.5. The unfavorable negative torques are eliminated using an optimal pitch control strategy, which maximizes the tangential force coefficients and thus the torque coefficients by iterations of all possible relative angles of attack for various tip speed ratios. As a result, the power coefficient is significantly improved especially at low tip speed ratios in the range of zero to three (λ = 0 – 3). Blade pitch control can also solve the self-starting problem and reduce the vibration of vertical axis wind turbines.

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