SIMULASI NUMERIK PADA DIFFUSER AUGMENTED WIND TURBINES DENGAN ROTOR GANDA KONTRA ROTASI

KURVATEK ◽  
2018 ◽  
Vol 3 (1) ◽  
pp. 13-20
Author(s):  
Yosua Heru Irawan ◽  
M Agung Bramantya

Wind energy is one form of renewable energy in Indonesia and its potential is very large to be utilized. Wind energy can be converted into electrical energy using wind turbines. Horizontal axis wind turbine will be the subject of this study, where the wind turbine model will be given additional diffuser. In addition, this wind turbine model will also be developed from a single rotor wind turbine into a double rotor wind turbine with opposite rotation direction or counter rotation. This research uses numerical simulation method using ANSYS Fluent software to know wind turbine performance. Simulations were performed at wind speeds of 3 m/s, with the ratio of the length and diameter of the inlet diffuser 0.5; 1; 1.5; 2; and 2.5. Based on the simulation results, it can be seen that the greater the ratio of inlet length and diameter, the mechanical power generated by the wind turbine rotor is greater. Double rotor wind turbine with a length ratio and 2.5 inlet diameter produces the highest performance on the front rotor and rotor rear. The greater the ratio of the length and diameter of the inlet, the mechanical power generated by the front rotor and the rotor inside the diffuser also increases.

2021 ◽  
Vol 104 ◽  
pp. 83-88
Author(s):  
Rahmat Wahyudi ◽  
Diniar Mungil Kurniawati ◽  
Alfian Djafar

The potential of wind energy is very abundant but its utilization is still low. The effort to utilize wind energy is to utilize wind energy into electrical energy using wind turbines. Savonius wind turbines have a very simple shape and construction, are inexpensive, and can be used at low wind speeds. This research aims to determine the effect of the slot angle on the slotted blades configuration on the performance produced by Savonius wind turbines. Slot angle variations used are 5o ,10o , and 15o with slotted blades 30% at wind speeds of 2,23 m/s to 4,7 m/s using wind tunnel. The result showed that a small slot angle variation of 5o produced better wind turbine performance compared to a standard blade at low wind speeds and a low tip speed ratio.


2014 ◽  
Vol 658 ◽  
pp. 135-140 ◽  
Author(s):  
Radu Saulescu ◽  
Codruta Jaliu ◽  
Olimpiu Munteanu ◽  
Oliver Climescu

A specific problem of the wind turbines refers to the difference between the low rotation speed of the wind turbine rotor and the high rotation speed needed for the electrical generator. Usually, the adaptation between the speed of the turbine rotor and the electrical generator speed is achieved by means of a speed increaser. A recent alternative relates to the use of coaxial counter-rotating wind turbines, which can achieve higher power and improve the conversion efficiency of the wind energy into electrical energy (up to 25%) with a reduced cost of approx. 20-30% compared to similar single rotor turbines. Conceptually, the counter-rotating wind turbine systems can integrate a particular generator wherein the rotor is coupled to a row of blades and the stator with another row of blades, or a commonly generator, coupled to a differential planetary gear, that allows the summation of the blades motions.The paper describes and analyzes kinematic and dynamic aspects of a system consisting of two coaxial counter-rotating turbines and a generator, interconnected by a planetary gear with two inputs (the two turbines) and an output (the generator). The algorithm is based on the property of the differential planetary gear of adding two input motions into one output motion. The kinematic and dynamic parameters of the planetary gear are established in the paper, and a case study is further presented: a small wind turbine equipped with a transmission enabling input speed multiplication.


Author(s):  
John F. Hall ◽  
Dongmei Chen

The cost of electrical power produced by small wind turbines impedes the use of this technology, which can otherwise provide power to millions of homes in rural regions worldwide. To encourage their use, small wind turbines must capture wind energy more effectively while avoiding increased equipment costs. A variable ratio gearbox (VRG) can provide this capability to the simple fixed-speed wind turbine through discrete operating speeds. This is the second of a two-part publication that focuses on the control of a VRG-enabled wind turbine. The first part presented a 100 kW fixed speed, wind turbine model, and a method for manipulating the VRG and mechanical brake to achieve full load operation. In this study, an optimal control algorithm is developed to maximize the power production in light of the limited brake pad life. Recorded wind data are used to develop a customized control design that is specific to a given site. Three decision-making modules interact with the wind turbine model developed in Part 1 to create possible VRG gear ratio (GR) combinations. Dynamic programming is applied to select the optimal combination and establish the operating protocol. The technique is performed on 20 different wind profiles. The results suggest an increase in wind energy production of nearly 10%.


2018 ◽  
Vol 4 (2) ◽  
pp. 93
Author(s):  
Delffika - Canra ◽  
Meri Rahmi ◽  
Emin Haris

Generally, wind energy sources in Indonesia's coastal areas is one of the potential sources of renewable energy (renewable energy resources) which are abundant, environmentally friendly and renewable. Savonius wind turbines can produce relatively high torque even at low wind speeds. Because it is very well developed to produce electrical energy. To get a large electric power, a large turbine construction is also needed which also certainly requires a large cost. For this reason, it is necessary to develop the dimensions of this wind turbine construction which is known as aspect ratio (Ar). The Ar that has been researched is the blade section, and other values. While the arch depth or the length of the blade arc in U -type is still likely to be researched. Therefore, it is necessary to do research on the U-type blade arc to get greater power than before. In addition to the experimental method with a prototype of the U type Savonius wind turbine with a number of 2 blades, a software-based simulation method will be carried out to analyze the air flow on the wind turbine blade. Parameters varied only with the aspect ratio of the arc length and blade cross section width, other parameters follow the previous research. This analysis will be a comparative data with experimental methods. The expected simulation results obtain the best aspect ratio (Ar) blade in capturing wind energy.


Author(s):  
Scott Post ◽  
Curtis Boirum

This paper describes a semester-long class project for students in junior-level Fluid Mechanics courses. The goals of the project are to introduce students to engineering design and to incorporate material from other courses in engineering graphics, instrumentation and measurements, and manufacturing processes in a single project. Each team of 3–4 undergraduate students had to design, build, and test a scale model horizontal-axis wind turbine. The wind turbines were designed using solid modeling software, and constructed using either a rapid prototyping machine or a CNC milling machine. The wind turbines were about 15 to 20 cm (6 to 8 inches) in diameter when built, and were placed in a wind tunnel for testing. A small DC motor was used as an electric generator and coupled to the wind turbines through a straight shaft. A variable resistor was incorporated into the circuit so that the rotational speed of the turbine-generator apparatus could be varied. Students were graded based on the efficiency of their wind turbines in converting wind kinetic energy into electrical energy. An additional requirement was for the students to perform a literature review to assess the state of the art in commercial wind turbine technology.


2018 ◽  
Vol 51 ◽  
pp. 01005 ◽  
Author(s):  
Naima Jouilel ◽  
Mohammed Radouani ◽  
Benaissa El Fahime

Modeling wind energy conversion systems is a difficult task that requires the use of a unified language gathering all aspect of energies involved such as kinetic energy, mechanical energy, and electrical energy. Bond Graph methodology is an appropriate tool to analyze wind turbine dynamic behavior since the whole system is modelled in the same frame. Herein, a methodology for HAWT's rotor modeling is proposed based on Bond Graph, aerodynamic laws and Rayleigh Beam theory. It takes into consideration the profile, chord, and twist change along the blade. The model is validated using 20-Sim software and then compared to other models from literature. Simulation results show a better value of power coefficient in comparison with works using the same tools.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wang Wenxin ◽  
Chen Kexin ◽  
Bai Yang ◽  
Xu Yun ◽  
Wang Jianwen

AbstractGiven the increasing trend of using wind energy in cities, the utilization of distributed wind energy in cities has been widely concerned by researchers. The related research on the micro-site selection of wind turbines, a sub-project of the Task27 project of the International energy agency, was continued in this paper. The wind speed data of an observation station near Hohhot, Inner Mongolia, with a range of 10–19 m were collected. The evaluation included wind direction, Weibull parameter characteristics, and turbulence intensity. The potential energy output in 10 different heights was estimated using commercial horizontal and vertical axis wind turbines of the same power. Results showed that the following: the three-parameter Weibull distribution model can well describe the statistical properties of the wind speed in this site. The wind speed distribution model constructed from extrapolation parameters reflects the wind speed statistical properties out of detection positions to a certain extent. The wind energy density of the vertical axis wind turbine is slightly lower than that of the horizontal axis wind turbine. Furthermore, more power can be generated from March to May.


Author(s):  
Massimo Rivarolo ◽  
Alessandro Spoladore ◽  
Carlo Cravero ◽  
Alberto Traverso ◽  
Andrea Freda ◽  
...  

Electrical energy production by wind energy has assumed more and more relevance in the last years. This paper presents the design of a ducted horizontal axis wind turbine, in order to enhance the performance. The study compares the energy production of a ducted turbine to a traditional free turbine, highlighting the different features. In the first part of the work, different possible geometries have been investigated through a quasi-1D model, using correlations from literature to evaluate pressure, velocity and producible electrical power by the wind turbine. A 3D CFD model, in a set of configurations, has confirmed the preliminary results. The most promising geometries have been selected by combining the outputs of the two models. In order to confirm the results obtained by the numerical models, a test rig has been assembled at the wind tunnel of the Polytechnic School of the University of Genoa. Different possible configurations of the wind energy harvesting system have been tested: free turbine, horizontal duct, convergent duct and convergent-divergent ducts (with the turbine installed in the throat section). In particular, the convergent-divergent duct has shown the best results, with an increase factor close to 2.5 in terms of produced power, compared to the reference free turbine. Finally, the results obtained in the experimental campaign have been used to validate the two models (1D and 3D CFD). Considering the advantages in terms of energy production, this kind of configuration can be considered an interesting solution for many different situations, including energy harvesting.


Author(s):  
Michael McWillam ◽  
David Johnson

The engineering of wind turbines is not fully mature. There are still phenomena, particularly dynamic stall that cannot be accurately modeled. Dynamic stall contributes to fatigue stress and premature failure in many turbine components. The three dimensionality of dynamic stall make these structures unique for wind turbines. Currently flow visualization of dynamic stall on a wind turbine rotor has not been achieved, but these visualizations can reveal a great deal about the structures that contribute to dynamic stall. Particle Image Velocimetry (PIV) is a powerful experimental technique that can take non-intrusive flow measurements of planar flow simultaneously. High-speed cameras enable time resolved PIV can reveal the transient development. This technique is suited to gain a better understanding of dynamic stall. A custom 3.27 m diameter wind turbine has been built to allow such measurements on the blade. The camera is mounted on the hub and will take measurements within the rotating domain. Mirrors are used so that laser illumination rotates with the blade. The wind turbine will operate in controlled conditions provided by a large wind tunnel. High-speed pressure data acquisition will be used in conjunction with PIV to get an understanding of the forces associated with the flow structures. Many experiments will be made possible by this apparatus. First the flow structures responsible for the forces can be identified. Quantitative measurements of the flow field will identify the development of the stall vortex. The quantified flow structures can be used to verify and improve models. The spatial resolution of PIV can map the three dimensional structure in great detail. The experimental apparatus is independent of the blade geometry; as such multiple blades can be used to identify the effect of blade geometry. Finally flow control research in the field of aviation can be applied to control dynamic stall. These experiments will be subject of much of the future work at the University of Waterloo. Potentially this work will unlock the secrets of dynamic stall and improve the integrity of wind turbines.


2020 ◽  
Author(s):  
wang Wenxin ◽  
Bai Yang ◽  
Chen Kexin ◽  
Wang Jianwen ◽  
Qin Chaofan

Abstract Background:Given the increasing trend of using wind energy in cities, the utilization of distributed wind energy in cities has been widely concerned by researchers. The related research on the micro-site selection of wind turbines, a sub-project of the Task27 project of the International energy agency, was continued in this paper.Methods:The wind speed data of an observation station near Hohhot, Inner Mongolia, with a range of 10-19 m were collected. The evaluation included wind direction, Weibull parameter characteristics, and turbulence intensity. The potential energy output in 10 different heights was estimated using commercial horizontal and vertical axis wind turbines of the same power.Results:The three-parameter Weibull distribution model can well describe the statistical properties of the wind speed in this site. The wind speed distribution model constructed from extrapolation parameters reflects the wind speed statistical properties out of detection positions to a certain extent.Conclusions:The wind energy density of the vertical axis wind turbine is slightly lower than that of the horizontal axis wind turbine. Furthermore, more power can be generated from March to May.


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