Yazar "Akansu Y.E." seçeneğine göre listele

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    Control of flow around square cylinders at incidence by using a rod
    (American Institute of Aeronautics and Astronautics Inc., 2005) Sarioglu M.; Akansu Y.E.; Yavuz T.
    Aerodynamic characteristics of a square cylinder at incidence were investigated experimentally in the wake of a small rod at a Reynolds number of 3.4 × 104. The dimensionless gap L/D was varied from 1.71 to 8.00. Depending on the spacing L/D, two flow patterns with and without vortex shedding from the rod were observed. Pressure measurements on the rod and square cylinder and hot-film measurements in the wake of the cylinder were carried out. The combined influences of the rod and angle of incidence on the pressure distributions and vortex-shedding phenomenon were investigated. Without the rod, as the incidence increases from 0 deg, the reattachment on the lower side surface of the square cylinder occurs at the vicinity of 13 deg, and this corresponds to a jump in the Strouhal number. However, when the rod was set upstream of the square cylinder, the reattachment occurs at smaller angles of incidence depending on L/D. At zero angle of incidence, the minimum value of drag on the square cylinder is obtained for L/D = 2.0 and produces a drag that is 30% that of the square cylinder without rod. For L/D = 1.71, with increasing the angle of incidence CD values approximate to those of the square cylinder without rod. In the case of L/D ? 2.7, there is a considerable decrease in CD in the region ??10 deg; however, the effect of the rod on CD decreases beyond 9 = 10 deg. Copyright © 2005 by the American Institute of Aeronautics and Astronauties, Inc. All rights reserved.
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    The effect of a novel spark-plug plasma synthetic jet actuator on the performance of a PEM fuel cell
    (Elsevier Ltd, 2019) Seyhan M.; Akansu Y.E.
    The effect of oscillating flow on the performance of a single cell PEM fuel cell is investigated at the cathode side. The oscillating flow is generated with a Spark-plug plasma synthetic jet (SPSJ) actuator. The PEM fuel cell is directly connected to SPSJ actuator. The significant performance improvement of the PEM fuel cell is by this approach. At two different hydrogen and air flow rates, necessary experiments are performed to obtain the polarization curves and current–time history plots at a constant voltage. The results indicate that the peak power output of the PEMFC increases up to 11% compared to the case without a SPSJ actuator. It can be concluded that the plasma synthetic jet actuator producing oscillating flow enhances the oxygen concentration and diffusion rate at the cathode channel of the PEM fuel cell. © 2019 Elsevier Ltd
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    The effect of attack angle to vortex shedding phenomenon of flow around a square prism with a flow control rod [Akiş kontrol çubugu i·le kare kesi·tli· bi·r küt ci·si·m etrafindaki· akiş kontrolünde hücum açisinin gi·rdap kopma olayina etki·si·]
    (2011) Akansu Y.E.; Özmert M.; Firat E.
    In this study, the effect of attack angle on vortex shedding phenomena in the case of flow around the square prism as a bluff body and the circular rod which used as flow control component was experimentally investigated. While the value of attack angle equal to 0°, the upstream control rod and square prism are in tandem arrangement to free stream. Experiments were conducted at Reynolds number of 1.0 × 10 4, for the diameter ratio of d/D=0.25, the attack angle between 0° ? ? ? 90°, and the value of normalized distance between two prism L/D is 1, 2, 3, and 4. The velocity measurements were conducted by means of constant temperature anemometer (CTA) as well as vortex shedding frequencies obtained by the spectral analysis of velocity-time history. Characteristics of the vortex formation region and location of flow attachments, reattachments, and separations were observed by means of the smoke-wire flow visualizations. At the angle of attack 0° of the location L/D=2 and 3, the flow structure that possess high vorex shedding frequency which causes remarkable reductions on the drag force and significant increase in the heat transfer was obtained. This flow structure continous to decrease with increasing attack angle up to around 10°. By further increasing of attack angle, the effect of flow control rod on vortex shedding frequency disappears completely. ©2008 TIBTD Printed in Turkey.