Browsing by Author "Yayla, S."

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The Effect of Angle of Attack on the Flow Structure Over the Nonslender Lambda Wing
(2013) Yayla, S.; Canpolat, C.; Sahin, B.; Akilli, H.
The aim of the current study at first stage is to demonstrate the general flow structure qualitatively using the dye visualization technique. Secondly, the instantaneous flow data taken by a Stereoscopic Particle Image Velocimetry (stereo-PIV) over a stationary nonslender lambda wing is used to determine the time-averaged flow topology in order to provide detailed information about crucial events like formation of leading edge vortices and vortex breakdown in plan-view planes and cross-flow planes. The flow structure close to the lambda wing surface and development of the vortex breakdown are investigated as functions of angles of attack within the range of 7°≤α≤17°. Experimental analyses are composed of time-averaged patterns of streamlines, vorticity contours, transverse and streamwise velocity components, Reynolds-stress correlations, distribution of fluctuating velocities, and turbulent kinetic energy. Results show that the angle of attack has a substantial influence on the flow behavior on the nonslender lambda wing surface. © 2012 Elsevier Masson SAS. All rights reserved.
Effects of Flexible Splitter Plate in the Wake of a Cylindrical Body
(Isfahan University of Technology, 2016) Teksin, S.; Yayla, S.
In the wake of the bluff bodies rigid splitter plates are known to control vortex shedding. In this study, the problem of flexible splitter plate in the wake of circular cylinder was investigated using Particle Image Velocimetry (PIV) experimentally. In this case; the splitter plate which has a certain amount of modulus of elasticity freely deforms along its length because of the fluid forces on plate. The diameter of cylinder, D was 60 mm while the Reynolds number based on the cylinder diameter is kept constant as 2500, the characteristics length of the control element, L was tested for four different cases that the values of L/D were 0, 1.25, 2.25, 2.5 in the investigation. As a consequence, turbulent kinetic energy, TKE, velocity vector field >V<, vortex>ω<, Reynolds stress >u'v'<, root mean square of streamwise and transverse velocities, > urms vrms >/U were analyzed. It is found that the variable parameter of L/D affects the flow structures and also noted that it decreased maximum level of all characteristic values. © 2016, Isfahan University of Technology.
Effects of Perturbation on the Flow Over Nonslender Delta Wings
(American Institute of Aeronautics and Astronautics Inc, AIAA, 2015) Canpolat, C.; Sahin, B.; Yayla, S.; Akilli, H.
An experimental investigation is presented to reveal the flow physics and turbulence statistics of nonslender delta and diamond wings with a sweep angle of Λ = 40° under perturbation condition with the amplitude of Δα = +Δαsinωet = ±0.5° during Te=2π/ωe= 0.5s. The experiments are carried out using the techniques of dye visualization and Stereoscopic Particle Image Velocimetry (stereo-PIV) on the plan view and cross flow plane for the cases of stationary and perturbed wing as the angle of attack is varied within 7°≤α≤17°. In order to perform a comparison based on the wing planform, diamond wing is designed from the composition of same shape of the delta wing and an attachment part mounted on its trailing edge. This study also provides information about effects of trailing edge attachment mounted on a generic nonslender delta wing under current test conditions. It can be concluded that perturbation is beneficial in the control of flow over both wings at relatively high angles of attack, α.The duration required for occurrence of flow control increases for the current period and time of perturbation, when the trailing edge attachment (diamond wing case) is employed. Beyond this, trailing edge attachment takes role in attenuation of turbulence statistics, where leading edge vortex breaks down. © 2015, American Institute of Aeronautics and Astronautics, Inc.
Effects of Trailing-Edge Attachment on the Flow Structure Over a Generic Delta Wing
(Asce-amer Soc Civil Engineers, 2017) Canpolat, C.; Yayla, S.; Sahin, B.; Akilli, H.
The objective of this work is to reveal the significance of a trailing-edge attachment on the flow structure over a generic nonslender delta wing using the dye visualization technique on the top-view plane. Instantaneous images are acquired by stereoscopic particle image velocimetry (stereo-PIV) to calculate time-averaged flow data, with angle of attack, a, and yaw angle,., are varied within 7 degrees <= alpha <= 17 degrees and 0 degrees <= theta <= 15 degrees, respectively. It is shown that time-mean locations of vortex breakdown for the nonslender delta and lambda wings occur in the field close to the wings. As a result, no remarkable alteration is observed for the spatial locations of the vortex breakdown. The experiments also show that the., which is a crucial parameter, alters the flow structure over the nonslender delta wing substantially compared with the lambda wing. It is concluded that the trailing-edge attachment plays vital role when. becomes effective. (C) 2017 American Society of Civil Engineers.
Numerical Analysis of a Two-Phase Flow (Oil and Gas) in a Horizontal Separator Used in Petroleum Projects
(Isfahan Univ Technology, 2019) Yayla, S.; Kamal, K.; Bayraktar, S.
In the present paper, two-phase three-dimensional turbulent flow simulations are carried out by applying computational fluid dynamics (CFD) technique to the internal flow of a horizontal separator that is used in petroleum industry. Two different geometries are considered; the separator with a straight plate at the top and the separator with the straight plate on the side of the separator. Effects of the location, distance between the inlet of the separator and the diverter plate and inlet velocity on the separation efficiency are investigated by employing the standard k- epsilon turbulence model. For these purposes, three different distances between the straight diverter plate and the inlet to the separator (0.1 m, 0.15 m and 0.2 m) and four different velocities (0.25 m/s, 0.5 m/s, 0.75 m/s, and 1 m/s) are taken into account by means of Euler mixture model. It is revealed that the maximum separation efficiency is 99.772% when the mixture enters the separator from the top with the inlet velocity of 0.25 m/s and the plate is located 0.2 m away from the inlet section of the separator. An inverse correlation is detected between the inlet velocity and the efficiency of the separation since increasing the inlet velocity decreases the efficiency of the separation.
Numerical Study of Three-Winged Passive Micromixer Based on Sar Principle
(Avestia Publishing, 2021) Jomha, M.; Yayla, S.
The passive three wings micromixer is presented according to the SAR principle. CFD numerically examined the mixer's efficiency for a wide range of Reynolds numbers up to 100. Three factors were used to test the efficiency of mixer performance. These three were the change in the fluids inlets velocity, connections with twisted angle, and a variable diameter obstacle to validate the submitted model. Besides, the pressure drop was studied for three types of micromixers. When comparing results, we found promising results in Reynolds numbers less than 0.1 for every style. Crucial differences were found between them when the degree of connections being twisted had increased, especially at 1.5 revolutions. The mixing index was greater than 90% independent of the Reynolds numbers and all ratios. Additionally, a drop of pressure was achieved along with the mixer of the twisted type 1.5 rev. higher than other mixers. © 2021, Avestia Publishing. All rights reserved.
Wind Energy Potential on the Coast of Lake Van
(Taylor & Francis inc, 2012) Yumak, H.; Ucar, T.; Yayla, S.
A wind measurement mast has been erected to determine the wind potential of north eastern coast of Lake Van located in Mamedik wind corridor. Yuzuncu Yil University campus is also located in this area. Wind speed sensors are installed at 10 m and 30 m above ground level (AGL) and a wind vane at 30 m. The wind and meteorological parameters have been measured for a period of 28 months from 19 March 2004 till 31 July 2007. The measured data have been analyzed by using WAsP software and wind power potential has been assessed for the site under consideration.