Aerospace Science and Technology
Sahel Alasvand; Mostafa Kazemi; Mahmood Mani
Abstract
The noise of wind turbines is mainly of aerodynamic origin and is caused by the impact of the flow on the turbine blade. Therefore, improving the behaviour of the flow around the turbine and reducing aeronoise can result in reducing its annoying noise. In the first step of this research, a suitable serration ...
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The noise of wind turbines is mainly of aerodynamic origin and is caused by the impact of the flow on the turbine blade. Therefore, improving the behaviour of the flow around the turbine and reducing aeronoise can result in reducing its annoying noise. In the first step of this research, a suitable serration is selected according to the physics of the flow, and then it is installed on the leading edge of the blade in such a way that it does not cause the power loss of the turbine. All the studies have been done experimentally in the wind tunnel and with the help of power, pressure and air velocity measurements in the wake and in the different free stream velocities. The results showed that the pressure fluctuations in the model equipped with a serrated blade have decreased by 4-9% on average in different areas compared to the simple Savonius. On the other hand, the results of the frequency analysis of the anemometer sensors also showed that in the dominant frequencies, the serration caused the range of phenomena to decrease. These results were obtained in such a way that the power measurement showed that the maximum power value of the turbine equipped with serrated blade experienced an increase of nearly 19%. On the other hand, the velocity profile in the wake also shows a greater deficit in the flow around the modified Savonius, which confirms the decrease in the output momentum from the turbine and consequently the increase in power.
Aerospace Science and Technology
Bahareh Mojarrad; Saeed Oveisi; Mostafa Kazemi; Mahmoud Mani
Abstract
The primary objective of this study was to demonstrate how plasma actuators could be used to discharge a perpendicular dielectric barrier as a virtual Gurney flap. This study utilized wind tunnel experiments on a flat plate airfoil. Each experiment is conducted at two different free flow velocities of ...
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The primary objective of this study was to demonstrate how plasma actuators could be used to discharge a perpendicular dielectric barrier as a virtual Gurney flap. This study utilized wind tunnel experiments on a flat plate airfoil. Each experiment is conducted at two different free flow velocities of ten and twenty meters per second. To study and extract the aerodynamic phenomena generated by plasma actuators and to compare them to the Gurney phenomena of a physical flap, velocity profiles in the model sequence were measured using a hot wire flow meter in two different longitudinal positions relative to the model. All experiments were conducted from five distinct vantage points, 0, 2, 4, 6, and 8, and plasma actuators were activated in two distinct settings to extract concepts under a variety of conditions. Wind tunnel experiments indicate that downward sequence transfer occurs when plasma actuators are used. Additionally, there are two distinct types of vortex shedding on the model's back: one that resembles Karman vortex shedding and another that occurs below the model. The observation of velocity profiles demonstrates that the deformation of the sequence caused by the use of plasma actuators is very similar to that caused by an airfoil sequence equipped with a physical Gurney flap.
Aerospace Science and Technology
Parisa Ghanooni; Mostafa Kazemi; Mahmoud Mani
Abstract
This study focuses on improving performance of a supercritical wing equipped with winglets at different cant angles. This study aims to experimentally investigate the variation of aerodynamic performance of a supercritical wing of NASA Sc (2)-0410 airfoil at lower Reynolds numbers with winglets at various ...
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This study focuses on improving performance of a supercritical wing equipped with winglets at different cant angles. This study aims to experimentally investigate the variation of aerodynamic performance of a supercritical wing of NASA Sc (2)-0410 airfoil at lower Reynolds numbers with winglets at various cant angles. The tests were performed by measuring the lift and drag force using a three-component balance within a broad range of angle of attack from -4 to 20 degrees and at three different subsonic flow velocities. Results include changes in lift, drag, and aerodynamic performance for each winglet cant angle compared to the baseline wing. The results show that winglets generally increase the lift force and decrease the drag force by decreasing the size and strength of the wingtip vortices. Moreover, the optimal winglet for each case is extracted based on the aerodynamic performance provided by each winglet. In order to better and more accurately compare the effect of different mounting angles of the winglet on the aerodynamic performance of the base wing, the impact of each winglet is shown separately. Accordingly, it is observed that the winglets with angles of 0o and 15 o, namely W0 and W15, have shown good performance in increasing the lift coefficient. Also, the winglet with 90 degrees has shown good performance in creating the least drag force.