Browsing by Author "Bayraktar, Seyfettin"

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Computational Analysis of Effects of Location of the Diverter Plate and Inlet Velocity on the Efficiency of Two-Phase Flow Separator
(Gazi Univ, 2019) Yayla, Sedat; Kamal, Karwan; Bayraktar, Seyfettin
Two-phase horizontal gravity separators are generally used in the petroleum industry for gas and liquid separation. There are several studies in the relevant literature that reports various methods to determine the optimum diameter and length of the separator. Although the diverter plate is used to increase the separation speed, there is not any exact approach for specifying the appropriate location of the diverter plate on the inlet pipe. In the present study, the main volume of the separator is defined for a particular amount of mixture of oil and gas. Effects of the location of the diverter plate and inlet velocity on the separation efficiency are investigated for three locations of the diverter plate (100 mm, 150 mm, 200 mm) and four different inlet velocities (0,25 m/s, 0,5 m/s, 0,75 m/s, 1 m/s) by means of computational fluid dynamics (CFD) method. Two-phase, three-dimensional (3D) and fully turbulent flow simulations reveal that the highest separation efficiency is obtained as 99% when the straight diverter plate is 200 mm far away from the top inlet and the inlet velocity is 0,25 m/s.
Computational Fluid Dynamics and Heat Transfer Analysis for a Novel Heat Exchanger
(Asme, 2015) Ma, Haolin; Oztekin, Dennis E.; Bayraktar, Seyfettin; Yayla, Sedat; Oztekin, Alparslan
Computational fluid dynamics (CFD) and heat transfer simulations are conducted for a novel heat exchanger. The heat exchanger consists of semi-circle cross-sectioned tubes that create narrow slots oriented in the streamwise direction. Numerical simulations are conducted for Reynolds numbers (Re) ranging from 700 to 30,000. Three-dimensional turbulent flows and heat transfer characteristics in the tube bank region are modeled by the k-e Reynolds-averaged Navier-Stokes (RANS) method. The flow structure predicted by the two-dimensional and three-dimensional simulations is compared against that observed by the particle image velocimetry (PIV) for Re of 1500 and 4000. The adequate agreement between the predicted and observed flow characteristics validates the numerical method and the turbulent model employed here. The three-dimensional and the twodimensional steady flow simulations are compared to determine the effects of the wall on the flow structure. The wall influences the spatial structure of the vortices formed in the wake of the tubes and near the exit of the slots. The heat transfer coefficient of the slotted tubes improved by more than 40% compare to the traditional nonslotted tubes.
Numerical Studies on the Oil-Water Mixture Separation by Corrugated Plates With Hooks and Holes in Various Shapes and Configurations
(Springer Heidelberg, 2024) Oruc, Mehmet; Salih, Muhammed; Yayla, Sedat; Bayraktar, Seyfettin
The present paper reports the studies on the separation efficiency of a water-oil mixture in the second process in which the water consists of 5-10% crude oil in general. The mixture in this stage was exposed to an additional separation. For this purpose, corrugated plates with L-shaped hooks and holes on the top intersection of the plates were used. Before handling some design factors such as the hole pattern at the intersection of the inclined plates, the inclination angle of the corrugated plates, and the hooks attached to the plates, an experimental rig was designed to validate the computational fluid dynamics (CFD) results. Upon achieving a successful comparison, the numerical studies were extended to reveal the effects of hole shapes and arrangement pattern and the angle of the plates. It was found that attaching L-shaped hooks to the plates improves separation effectiveness by 2% as compared to hookless plates. The parametric CFD studies reveal that the hole shapes do not affect considerably the separation efficiency while raising the plates increases the efficiency slightly and pressure drop dramatically.
Wall Proximity Effects on Flow Over Cylinders With Different Cross Sections
(Canadian Science Publishing, Nrc Research Press, 2014) Bayraktar, Seyfettin; Yayla, Sedat; Oztekin, Alparslan; Ma, Haolin
This paper presents the results of a numerical study on flow characteristics over circular, square, and diamond cross-sectional cylinders. Investigations are performed in a two-dimensional domain using the finite volume discretization method solver for Reynolds number, Re = 20 000. Unsteady Reynolds averaged Navier-Stokes equations with Spalart-Allmaras turbulence model have been used as a turbulence closure. After the validation of the simulations with the available experimental data from the open literature, global characteristics of the flow field around different shaped cylinders near the wall have been presented. Effects of wall proximity on cylinders are investigated for four different gap width (G) to cylinder width (D) ratios.