Improvement of a Flanged Diffuser Augmented Wind Turbine Performance by Modifying the Rotor Blade Aerodynamic Design (original) (raw)
Related papers
Review on Diffuser Augmented Wind Turbine (DAWT)
International Journal of Integrated Engineering, 2019
Wind energy technology is one of the fastest growing alternative energy technologies. However, conventional turbines commercially available in some countries are designed to operate at relatively high speeds to be appropriately efficient, limiting the use of wind turbines in areas with low wind speeds, such as urban areas. Therefore, a technique to enhance the possibility of wind energy use within the range of low speeds is needed. The techniques of augmenting wind by the concept of Diffuser Augmented Wind Turbine (DAWT) have been used to improve the efficiency of the wind turbines by increasing the wind speed upstream of the turbine. In this paper, a comprehensive review of previous studies on improving or augmentation power of horizontal axis wind turbines (HAWT) have been reviewed in two categories, first related with relative improvement of energy by improving the aerodynamic forces that affecting on HAWT in some different modifications for blades. Second, reviews different techniques to the augment the largest possible amount of power from HAWT focusing on DAWTs to gather information, helping researchers understand the research efforts undertaken so far and identify knowledge gaps in this area. DAWTs are studied in terms of diffuser shape design, sizing of investigation and geometry features which involved diffuser length, diffuser angle, and flange height. The conclusions in this work show that the use of DAWT achieves a quantum leap in increasing the production of wind power, especially in small turbines in urban areas if it properly designed. On the other hand, shrouding the wind turbine by the diffuser reduces the noise and protects the rotor blades from possible damage.
International Journal of Mechanical Engineering and Robotics Research
A diffuser-driven wind turbine (DAWT) was used in this paper to increase the efficiency of small-sized horizontal axis wind turbines (HAWTs) by surrounding them with a suitable distributor. The study included two steps: first, knowing the effect of the number of blades inside the diffuser in three configurations (2-blades, 3blades, and 4-blades), and secondly, showing the effect of the turbine position inside the diffuser in three cases based on the largest increase in wind speed in the diffuser. The numerical simulation investigation was carried out using 3D CFD ANSYS software by methods that rely on the SST k-ω turbulence model. The performance of the models was evaluated in terms of strength and aerodynamics coefficients, by calculating power coefficients CP. The study showed that the turbine at the entrance to the diffuser gives the highest performance compared to other cases. Where the increase at the inlet the power coefficient of the turbine the diffuser is (22% and 14%) compared to its position in the middle of the diffuser and the end of the diffuser, respectively.
Analysis of diffuser augmented wind turbine (DAWT) with flange and curved interior using CFD
Demand for electrical current is very high, especially for urban areas. To meet this condition, it is considered necessary to build a system that can function effectively. Micro-scale wind turbines would be a suitable choice to provide electricity particularly in residential areas. However, the wind velocity in Indonesia that only average less than 5 m/s may prove to be an obstacle that needs to be dealt with. One concept to solve problems in areas that have low wind speed is the use of Diffuser Augmented Wind Turbine (DAWT). DAWT is the development of horizontal wind turbines that use shroud as a concentrator that can boost a low wind speed. In this study, flanges and a curved interior were added to an existing DWAT design. A CFD simulation is used to obtain the suitable shape or design of the micro-scale wind turbines. Geometry obtained by using a diffuser with curved interior diameter of 115 mm, length 230 mm, the tilt angle of 9° and flange height is 0.6 h / D. Using this geometry specification, wind velocity is increased up to 2.15 times than free stream velocity.
CFD Investigation of Empty Flanged Diffuser Augmented Wind Turbine
International Journal of Integrated Engineering, 2020
Enclosing a wind turbine within a flanged diffuser is an innovative mean to increase the power harvested by turbine blades and it is among the most effective devices for increasing wind turbine energy. The geometric parameters of the empty flanged diffuser contribute efficiently to increase mass flow in the diffuser, hence improve the turbine performance. The study presents developed models of the geometrical parameters of an empty flanged diffuser that suitable for a scaled-down (1-6.5) horizontal axis wind turbine, the geometry parameters were involved the diffuser length, diffuser angle, flange height and flange angle. The geometrical models were verified and CFD investigated in 2-D and 3-D domains. Results obtained from CFD simulations show that, using a compact size of flanged diffuser within optimum geometrical parameters can give well acceptable for flow velocity increase at suggested place for the turbine rotor install. The increase in flow velocity is due to lower pressure at the outlet of the diffuser. As there is also a significant effect of the flange angle on increasing the flow velocity inside the diffuser where the rate of increase in wind velocity at turbine position was calculated for two flange angles (0 ̊ and 5). In another hand, the results also provided information on the velocity contours and velocity streamlines around diffuser geometry.
Numerical investigation of a Specially Designed Shrouded Wind Turbine with a flanged diffuser
The present study In this paper considers a new wind power technology called "DAWT" diffuser augmented wind turbine equipped with a brim "wind-lens" in order to investigate the aerodynamic performance characterized by this technology. To achieve this objective, many models of DAWT with different shroud dimensions have been numerically investigated using commercial CFD software's. Four types of compact-style DAWT were investigated experimentally. namely A-ii, B-ii, C-ii and S-ii type with different diffuser sectional shapes, length ratios L t /D and area ratios AR (exit area / throat area). The results showed that C-ii diffuser type of a cycloid curve for its sectional shape and with (L t /D =0.221 and AR =1.294) was the most promising shroud shape. It has been chosen in this thesis to investigate the effect of varying the radial tip clearance and the diffuser length on the aerodynamic performance of it. Three-dimensional transient Numerical Simulations were developed using the commercial CFD software ANSYS FLUENT, by solving the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations. Since this type of wind turbines consists of not only rotating blades but also a diffuser shroud with a brim located at the exit section of the diffuser, the flow field around the turbine is highly complex and unsteady from the results in the present work, C-ii diffuser type of a cycloid curve for its sectional shape (with length to diameter ratio L t /D=0.221 and area ratio A R =1.294) showed a good performance characteristic with C p equal to 0.92 at its design tip-speed ratio (λ=4.3). The results also concluded that C-ii with a tip clearance of 10 mm increases the output power coefficient by a factor of 2.25 compared with an un-shrouded one for the same wind speed and the same turbine characteristics. Increasing or decreasing the tip clearance away from 10 mm is not recommended as it showed an obvious decrease in the power coefficient C p due to the wake vortex generated around the turbine.
2021
In the present study, a structure consisting of a nozzle, a diffuser and a flange was constructed and modeled using a 3-dimensional, 3D, model using ANSYS-FLUENT 6.3. The aim of this study is to get the results for an optimum geometric shape that generates the highest wind velocity in front of the wind turbine installed inside the structure at the position where the air velocity is maximum. In addition, another aim of the study is to compare the results of the 3D model in case of the presence of the wind turbine inside the flanged diffuser augmented wind turbine, FDAWT, structure with the case of empty structure (without the turbine). The obtained 3D model results for velocity and pressure distributions within the study domain are compared with the results obtained previously by the present authors using 2D model. The present 3D study reveals that: The maximum velocity along the structure centerline at the throat of the FDAWT structure is increased by 70% before inserting the turbine. This value decreases to 63% after inserting the turbine, compared to 71% increase for the case of 2D modeling obtained by the present authors in previous studies. There is no change in the trends of the velocity and pressure distributions for the three cases.
Performance Investigation of Diffuser Augmented Wind Turbine
2017
Renewable energy resources are becoming an increasingly important part of our total energy demands due to the depletion of fossil fuels and the emergence of global warming. Wind turbines are one type of renewable resource that is very usual in the offshore site has a stronger and steadier wind speed which can produce more energy. It is a fact that wind power is the best dilute and unpredictable source of energy that works with efficiency of great importance in the conversion of this energy to electricity. It is a common practice to place wind turbines on ridges and hills to increase wind velocity over that of free stream. If a device (shroud) can be added to a bare turbine to increase wind velocity just as our research was to add shrouds by means of computer simulations to encase the “bare turbine” thereby increasing efficiency. Our goal is to find a particular shroud that maximized air mass flow through the turbine beyond the best bare turbine operational conditions. In this analys...
Simulation of Diffuser Augmented Wind Turbine performance
2016 World Congress on Sustainable Technologies (WCST), 2016
The main objective of this research is to optimize the diffuser design of Diffuser Augmented Wind Turbine (DAWT). Specifically, this study investigates the effect of different shapes of diffusers to develop the suitable diffuser parameter for the wind turbine power enhancement. For that purpose, two diffuser cases have been recommended as an effective design in increasing wind speed, using a validated model of a small commercial wind turbine (AMPAIR-300) in it were developed and each case is simulated and analyzed using design software Solid-works and Computational Fluid Dynamic (CFD) software Fluent-ANSYS-15, As per the study, for diffuser case-1,the diffuser splitter degrades the diffuser effect when its open angle higher than the diffuser open angle, for diffuser case-2 the diffuser splitter enhance the diffuser effect when its open angle lower than diffuser open angle, also adding inlet shroud directs the wind flow into the inlet of diffuser and the diffuser flange effect on the power enhancement was significant and also its induced axial load was significant, and it is recommended to study the optimum dimension of inlet shroud, diffuser flange and diffuser splitter to minimize the coefficient of thrust and to enhance the coefficient of power.
PERFORMANCE ANALYSIS OF DIFFUSER AUGMENTED HORIZONTAL AXIS WIND TURBINE
Diffuser augmented horizontal axis wind turbine design with a diffuser ring with a broad-ring flange at the exit periphery and a wind turbine inside it. diffuser ring helps for collecting and accelerating the approaching wind into wind turbine. The diffuser ring generates a low-pressure region in the exit neighborhood of the diffuser by vortex formation and draws more mass flow to the wind turbine inside the diffuser ring. To obtain a higher power output of the diffuser augmented wind turbine we have examined the optimal form of the flanged diffuser ring wind turbine. As a result a shrouded wind turbine equipped with a flanged diffuser has been developed and demonstrated power augmentation for a given turbine diameter and wind speed which is increased as compared to a standard (bare) wind turbine. In a field experiment using a three bladed wind turbine with a flanged diffuser shroud the output performance improved from standard (bare) wind turbine. The effect of diffuser " s shape performance greatly influenced and maximum wind speed increased 1.7 times with the selection of the appropriate diffuser shape. We conducted field tests using a real examination device with a diffuser and confirmed that the output power of the wind power generator increased by up to two times compared to that of a conventional turbine.The development and application of clean renewable energy resources have become a very important research Subject in recent past years. development of clean renewable energy resources are strongly accepted due to the limited availability of fossil fuels like coal, petrol, diesel and gases etc. and its negative impact on environment such as Global Warming, greenhouse gases emission etc. now a days clean renewable energy resources become a important contributor for reducing the world " s CO 2 emissions. Many governments have set target for future electricity generation from renewable such as 20% of electricity for Australia, 30-35% of electricity for the UK being generated by 2020 and 90% of electricity for the new zealand being generated from renewable sources. Among all clean renewable energy resources the wind energy has developed rapidly and about strongly play big role in new energy field. Wind energy output from wind turbine is directly proportional to the swept area (A) of turbine and cube of the wind velocity (V) in the turbine, as fallows[1]. P = ½ A V 3
Development of a Shrouded Wind Turbine with Various Diffuser Type Structures
IOP Conference Series: Materials Science and Engineering, 2019
The Shrouded wind turbine is an innovative mean to increase power generated by wind turbine. By encompassing the rotor with a diffuser structure, it is possible to increase the wind velocity through the turbine up to 1.8 times of free stream velocity. Specifically, this study is numerical simulations that investigate the effect of wind velocity on various diffuser type structures to develop shroud wind turbine. Numerical study was conducted using Computational Fluid Dynamics (CFD) method. A reasonable agreement between the computed results, available experimental data and previous simulation is obtained. The results show that simulation results have good agreement to experimental results. However, Curved diffuser give the best increment of wind velocity (at centreline diffuser) than flat diffuser and others, which is 84.18%, with the maximum velocity was 9.21 m/s. Regarding the velocity contour results, vortex in downstream curved diffuser is bigger than others. Therefore, suction e...