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Numerical analysis of Magnus wind turbine
Abstract
Magnus rotor is essentially a rotating cylinder that
generates lift due to Magnus effect. The effect has been
generating curiosity in a wide variety of fields ranging from
sports to alternate energy. The wind turbine under
investigation replaces tradition blades that have an airfoil
cross-section, with such Magnus rotors. In this paper, Magnus
wind turbines with three and five rotors have been analyzed at
various velocity ratios and tip speed ratios. The primary
motive is to find the best operating conditions for obtaining a
higher lift to drag coefficient for both three and five rotor
turbines, so that it can generate more power with the least
available wind. It has been observed that the higher ratio of
coefficient of lift to coefficient of drag values were obtained for
lower values of tip speed ratio, which is in contrast to the
requirement of higher tip speed ratios for turbines with airfoil
cross-section. This translates to the fact that Magnus wind
turbines can be an efficient solution to the generation of wind
power with less noise generation, since the noise generated by a
wind turbine decreases with decrease in the tip speed ratio.
... Traditionally, wind turbines with a horizontal axis of rotation are widely used in comparison with the vertical axis of rotation due to increased output power, providing approximately 10-20% greater output efficiency [4]. However, recent studies, such as those by Aneesh et al., [5] carried out numerical studies of Magnus wind turbines at different speeds and tip velocity coefficients. An interesting outcome is to obtain high values of the ratio of coefficients at low values of the tip speed ratio. ...
The problem of vortex disruption from the cylindrical blades of Magnus wind turbines is an urgent topic, which subsequently reduces the efficiency of the installation. Also, these cylindrical blades have a disadvantage in the form of low lift and high drag, as a result of which low operating efficiency is observed. Thus, the purpose of this work is a numerical study of the addition of a fixed blade to the cylindrical blades of a two-bladed wind turbine. Numerical studies were carried out for various angles of inclination of fixed blades from 0° to 60° using the Realizable k-ε turbulence model. The results of the study showed that with an increase in the angle of inclination of the fixed blade, the flow is disrupted, which is clearly visible at the maximum speed of rotation of the blades and the wind wheel, which causes a drop in lift, leading to a decrease in the efficiency of the wind turbine. Based on this, 0 degrees is the optimal angle of inclination of the fixed blade of a wind farm
... In [31,32] was analyzed Magnus effect in Cylinder based on Computational Fluid Dynamics method. Magnus effect based on Bernoulli's principle which stipulates that with increasing fluid velocity occurs static pressure decreasing, and fluid's potential energy is decreasing [33]. It can be described as a sidewise force acting on a rotating cylindrical or spherical solid object immersed in a gas or liquid, with the relative movement of them, as shown in Fig. 3. ...
Due to its special features, the Magnus effect wind turbine allows you to produce energy at a very low speed of the wind. This fact, as well as the growing interest in the of blockchain technology, makes it possible to use this type of wind turbine in private household as part of a distributed energy system in addition to solar panels. The article describes a two blades Magnus wind turbine whose cylinders rotate by means of embedded motors. To avoid a von Karman vortex street effect that occur when the cylinders rotate in the air flow, as well as to ensure maximum power, the optimal ratio between the wind speed and the cylinder rotation speed is determined using finite element analysis. Further, the obtained relations are used in the algorithms of the wind turbine control system.
When dealing with multirotor devices such as quadcopters or wind farms, the cost of blade-resolved large-eddy simulation (LES) becomes prohibitive. Combining LES with a family of lower-fidelity models, called actuator line models (ALMs), has grown in popularity in the past decade. ALM replaces full blade resolution with an array of actuator points or lines parameterized by aerodynamic lift/drag polar plots along the blades. Body forces computed based on these actuator points are then projected onto the LES flow mesh, mimicking the effect of rotating blades on the flow. However, the optimal projection radius and the associated LES grid size is often too restrictive for multirotor simulations. Recently, a new tip-correction-based filtered ALM (F-ALM) was proposed by Martínez-Tossas and Meneveau (2019), which allows coarser-than-optimal grids by avoiding the associated overprediction of thrust. In this work, F-ALM is implemented into a high-order, in-house LES code to simulate National Renewable Energy Laboratory Phase VI wind turbine. It is then followed by a comparison between the baseline ALM and the newly implemented F-ALM in terms of instantaneous and time-averaged flow fields and blade loads, revealing the advantages of F-ALM in preventing the overprediction of power on coarse grids. This encourages accurate and affordable simulations of multirotor devices in the future.
Experimental and calculated data on a wind turbine equipped with rotating cylinders instead of traditional blades are reported. Optimal parameters and the corresponding operational characteristics of the windwheel are given in comparison with those of the blade wind turbines.
The Magnus effect is well-known for its influence on the flight path of
a spinning ball. Besides ball games, the method of producing a lift
force by spinning a body of revolution in cross-flow was not used in any
kind of commercial application until the year 1924, when Anton Flettner
invented and built the first rotor ship Buckau. This sailboat extracted
its propulsive force from the airflow around two large rotating
cylinders. It attracted attention wherever it was presented to the
public and inspired scientists and engineers to use a rotating cylinder
as a lifting device for aircraft. This article reviews the application
of Magnus effect devices and concepts in aeronautics that have been
investigated by various researchers and concludes with discussions on
future challenges in their application.
Recently, a wind turbine utilizing the Magnus effect is appeared in Russia and Japan. Akita Magnus Association in Japan, proved that the Magnus effect could rotate a wind turbine, their cylindrical rotors were necessary to rotate by an electric motor. Therefore, the authors proposed a Magnus wind turbine which utilize Savonius wind turbines of high aspect ratio instead of the cylinders, since the Savonius wind turbines rotate without using electricity; we also looked into the technical feasibility of this system. In this paper, the authors report a result of a performance test of the Savonius type Magnus wind turbine in a wind tunnel test.
On the basis of experimental data for a windwheel with large-aspect-ratio (up to 14) cylinders, a method making it possible
to determine optimal parameters and main characteristics of a windwheel (power, highspeed) is proposed. Effects due to number
of cylinders, their aspect ratio and speed of rotation, stream velocity, and generator load are analysed.
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