Yazar "Genc, Mustafa Serdar" seçeneğine göre listele

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    ELECTRICITY PRODUCTION FROM PIEZOELECTRIC PATCHES MOUNTED OVER FLEXIBLE MEMBRANE WING AT LOW REYNOLDS NUMBERS
    (Yildiz Technical Univ, 2021) Bayramoglu, Nihal; Genc, Mustafa Serdar; Koca, Kemal; Altunal, Ahmet
    One of the most necessities of our age is undoubtfully to supply the ever-increasing energy demand. The world population is growing correspondingly with the developing technology and it causes more energy demand. Furthermore, when the fact that fossil fuel which is the most used energy source in the world in our age will inevitably come to an end is taken into consideration; the need to search for new energy sources has become an obligation. A piezoelectric effect is a crucial option that is used as a new energy conversion method and the researchers are trying to find ways to develop it. Thanks to their special molecular structure, the mechanical force applied to the piezoelectric materials creates an electric charge. In this way, the conversion of environmental vibrations into electrical energy can be achieved with piezoelectric materials. This experimental study aims to turn deformations and vibrational motions caused by the air on a flexible membrane wing into electrical energy thanks to piezoelectric materials. In this respect, a flexible membrane Zimmerman wing with a 1.5 aspect ratio was used. Smoke wire experiments were performed on the wing at 2.8x10(4) and 5.6x10(4) Reynolds numbers to capture and understand how the characteristics form of the flow over the flexible membrane surface is. Afterward, three different types of 4 piezoelectric materials were used over the flexible membrane wing and energy calculation was made over 470-ohm resistor at various Reynolds numbers and angles of attack.
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    Performance Assessment of Transition Models for Three-Dimensional Flow Over NACA4412 Wings at Low Reynolds Numbers
    (Asme, 2018) Karasu, Ilyas; Ozden, Mustafa; Genc, Mustafa Serdar
    The performance of the transition models on three-dimensional (3D) flow of wings with aspect ratios (AR) of 1 and 3 at low Reynolds number was assessed in this study. For experimental work; force measurements, surface oil and smoke-wire flow visualizations were performed over the wings with NACA4412 section at Reynolds numbers of 2.5 x 10(4), 5 x 10(4), and 7.5 x 10(4) and the angles of attack of 8 deg, 12 deg, and 20 deg. Results showed that the AR had significant effects on the 3D flow structure over the wing. According to the experimental and numerical results, the flow over the wing having lower ARs can be defined with wingtip vortices, axial flow, and secondary flow including spiral vortex inside the separated flow. When the angle of attack and Reynolds number was increased, wing-tip vortices were enlarged and interacted with the axial flow. At higher AR, flow separation was dominant, whereas wing-tip vortices suppressed the flow separation over the wing with lower AR. In the numerical results, while there were some inconsistencies in the prediction of lift coefficients, the predictions of drag coefficients for two transition models were noticeably better. The performance of the transition models judged from surface patterns was good, but the k-k(L)-omega was preferable. Secondary flow including spiral vortices near the surface was predicted accurately by the k-k(L)-omega. Consequently, in comparison with experiments, the predictions of the k-k(L)-omega were better than those of the shear stress transport (SST) transition.