Yazar "Seyhan, Mehmet" seçeneğine göre listele

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    An experimental investigation on the flow control of the partially stepped NACA0012 airfoil at low Reynolds numbers
    (Pergamon-Elsevier Science Ltd, 2024) Seyhan, Mehmet; Akbiyik, Hurrem
    An experimental study of flow control around a NACA0012 airfoil modified with fully and partially step geometry was conducted at Reynolds numbers of 6 x 104 and 1.2 x 105. Partially step geometries, the location of the step on the airfoil, and Reynolds number are varied to show their effect on aerodynamic performance and flow structures on the airfoil. Experimental results show that fully and partially step geometries are effective for flow control around the airfoil and aerodynamic performance enhancement. The maximum increase in lift coefficient is approximately 46%, and the stall angle is shifted about 1 degrees by the SM4 model at Re of 6x104 while the step geometry is on the pressure side. For a Reynolds number of 1.2 x 105, the highest increase in the lift-to-drag ratio of the airfoil is observed about 17.1 at an angle of attack of 6 degrees by the SM2 model when step geometry is placed on the pressure side of the airfoil. In the event of partially or fully stepped at the pressure side of the model, step flow structures, including the reattachment line, recirculation zone, and corner eddy, are obtained. However, even though the step geometry is at the suction surface of the model, the formation of a laminar to turbulent transition is observed. The overall results suggest that the partially stepped geometry length, Reynolds number, and step location side on the airfoil have an important role in flow control to improve aerodynamic performance for various angles of attack.
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    Öğe
    The effect of leading-edge tubercle on a tapered swept-back SD7032 airfoil at a low Reynolds number
    (Pergamon-Elsevier Science Ltd, 2022) Seyhan, Mehmet; Akbiyik, Hurrem; Sarioglu, Mustafa; Kececioglu, Sevda Ceren
    An experimental study is performed to research the effect of the implemented leading-edge tubercles on the tapered swept-back SD7032 airfoil at Re of 5.5 x 104 and 1.1 x 105. In this study, along with a baseline model with no tubercles (T0), in total four different configurations are used for analysis of the aerodynamic charac-teristics. In the other three models (T1, T2, T3) mainly different amplitude and wavelength modulations are studied. In all experimental studies, force measurements are performed by using a six-axis load cell force measurement device. To achieve detailed information on the flow field of all models, surface oil flow visuali-zation technique is used for visualization purposes at Re = 1.1 x 105. The geometric specifications of the model are the sweep angle of 300, the tip chord of 37.5 mm, the root chord of 112.5 mm, and the span of 300 mm. Airfoil models with the LE tubercles significantly improve lift curve at almost all AoAs as compared to the baseline model. The streamwise vortices are positioned together more closely leading to interaction with each other. Consequently, these interactions lead to an increase in turbulence. This increase in turbulence may lead to a better mixing and increase in momentum exchange in the boundary layer. Amongst the models (T1-T3), the best airfoil model is determined as T3, having a1 = 0.06c, lambda 1 = 0.5c, a2 = 0.015c, and lambda 2 = 0.125c parameters, in terms of lift, drag and CL/CD ratios.