Yazar "Caliskan, Meltem" seçeneğine göre listele

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    Flow investigation of circular cylinder having different cavities in shallow water
    (Elsevier Science Inc, 2021) Tantekin, Atakan; Ozdil, N. Filiz Tumen; Akilli, Huseyin; Caliskan, Meltem
    The control of the unsteady flow structure formed behind a cylinder placed horizontally in shallow water was analyzed experimentally using bare cylinder and cylinders with cavities having square and rectangular geometries, respectively. Reynolds number, Froude number and water height had been chosen as 5000, 0.27 and 90 mm, respectively and also these parameters were kept constant for all experiments. To consider the influence of height (h), the cylinder level was located at various heights from h: 0 mm to 60 mm. Furthermore, cavity angle (a) had been selected from 0 degrees, 80 degrees, 85 degrees, 90 degrees and 95 degrees to consider influence of cavity angle on flow. With the help of Particle Image Velocimetry (PIV), average velocity vectors were measured in two dimensions at many points simultaneously in a planar flow area. The results uncovered that large negative counter was observed at h: 37.5 mm in bare cylinder as well as cylinders having square and rectangular cavities at h: 45 mm. Also, no negative counter was observed for cylinders having rectangular cavity at h: 0 mm and a: 90 degrees and 95 degrees due to the bottom effect. Due to surface effects, a foci point was formed in all cylinders where close to the surface and close to the base. Two foci points and a saddle point were seen as they moved away from the surface for all cylinders. Also, the smallest vortex region was observed for cylinders having rectangular cavity at h: 37.5 mm and a: 90 degrees and 95 degrees in whole cylinders. Also, the highest drag coefficient (Cd) value was obtained for cylinder having square cavity at h: 52.5 mm and a: 80 degrees while the highest drag coefficient value was obtained for cylinder having rectangular cavity at h: 37.5 mm and a: 95 degrees.
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    Öğe
    Investigation of flow characteristics for triangular grooved shape cylinder at different heights in shallow water
    (Pergamon-Elsevier Science Ltd, 2021) Caliskan, Meltem; Tantekin, Atakan; Ozdil, N. Filiz Tumen; Akilli, Huseyin
    This study is an investigation and comparison of the flow characteristic around triangular grooved and bare cylinders, positioned horizontally in shallow water using Particle Image Velocimetry (PIV). Throughout the experiment, Reynolds number, Froude number and water height have been selected as 5000, 0.27 and 90 mm, respectively. To observe the effect of height (h) on the flow structure, cylinder is positioned at h: 0 mm, 15 mm, 22.5 mm, 30 mm, 37.5 mm, 45 mm, 52.5 mm and 60 mm. Moreover, grooved angle (a) has been changed from 0 degrees, 80 degrees, 85 degrees, 90 degrees and 95 degrees in shallow water to investigate the effect of grooved angle. The results show that the vortex forms vary according to the groove angle. It is seen that the vortex, the cylinders especially positioned at h: 0 mm and h: 60 mm, are affected owing to the surface and bottom effect. Furthermore, the largest Reynolds stress is observed at the h: 37.5 mm while the largest wake region is observed at the h: 52.5 mm. Also, the maximum Drag Coefficient (C-d) and Turbulence Kinetic Energy (TKE) are observed at h: 0 mm, a: 90 degrees for grooved cylinder and at h: 37.5 mm for bare cylinder, respectively.
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    Öğe
    Potential of Biogas and Electricity Production from Animal Waste in Turkey
    (Springer, 2021) Caliskan, Meltem; Tumen Ozdil, Naime Filiz
    In this paper, biogas potential produced from animal manure has been calculated using data for various regions of Turkey between 2007 and 2019. Moreover, generation of electricity potential that can be provided using biogas obtained from animal manure resources has been examined. The animal numbers subjected to the study have been reached via the Turkish Statistical Institute. The amount of animal manure, which is the basis for calculating the amount of biogas, has been calculated using the average number of animals and the animal weight. Eastern Anatolia and Central Anatolia Regions have the highest biogas potential with 19% compared with the other regions due to amount of manure obtained from animal. The finding of this study denotes that 76,448 x 10(6) m(3)potential of methane content can be obtained from biogas for the mentioned years, and 2,339,296 x 10(6) MJ potential of heating value can be obtained from this methane value. While the potential of electricity energy, which can be provided from animal manure wastes, has been 231,009 x 10(6)between 2007 and 2019 in Turkey, the total electricity consumption in 2007-2019 is 2,898,040 x 10(6) kWh. The results show that the potential electricity that can be provided from animal manure could meet 7.99% of the electricity consumed in the same years. Furthermore, the cost analysis of biogas facility, which is established in Eastern Anatolia Region, has been performed using circular economy model. According to calculations, the discounted payback period has been found to be 10 years.