WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collections

Permanent URI for this collectionhttps://hdl.handle.net/20.500.13091/2

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Now showing 1 - 4 of 4

Citation - WoS: 5
Citation - Scopus: 4
Baffle Angle Optimization of a Typical Shell and Tube Heat Exchanger
(Aip Publishing, 2025) Dogan, Sercan
An optimization study was conducted with the objective of enhancing the performance of a prevalent shell-and-tube heat exchanger model by modifying the baffle angles. The initial step was to verify the turbulence model results with numerical studies and analytical approaches documented in the literature. Subsequently, an investigation was conducted to address the contributions identified in the literature by determining the optimal angle for a shell-and-tube heat exchanger with six baffles. In the extant literature, the 36% baffle cut case, which is typically observed to provide the optimal heat transfer result, was selected for further analysis. A genetic algorithm optimization model embedded in a program was employed to evaluate the heat transfer and pressure drop jointly, thereby determining the optimal angles for all baffles. According to the performance evaluation criteria that considered both heat and flow results, the optimal angles were found to be 315 degrees, 195 degrees, 80 degrees, 340 degrees, 250 degrees, and 95 degrees from the first to the last baffle, respectively. Additionally, a comparison was conducted between the cross-arrangement baffle and the optimized baffle, which demonstrated superior performance by 5.5% and 19.5%, respectively, contingent on the increasing flow rate. Moreover, the novel configuration enabled enhanced mixing of the flow, which exhibited periodic movement in the staggered baffle configuration within the shell. This resulted in a notable enhancement of the heat transfer process.
Citation - WoS: 1
Citation - Scopus: 1
Drag Reduction by the Effect of Rounded Corners for a Square Cylinder
(Aip Publishing, 2024) Göktepeli, İlker
Flow around square cylinders has been studied via unsteady simulations done at a Reynolds number of Re = 100. In the present study, the effects of rounded corners on different flow characteristics have been evaluated. The main influence of rounded corners has been considered for various ratios (r*) up to 0.45 in terms of drag coefficient values. Flow stagnation points have been obtained in front of the square cylinders. These points constitute the maximum pressure. The cluster sizes for cross-stream velocity components are nearly the same. Viscous flow generates vortices around the top and bottom edges of the square cylinder. The produced vortices have been affected by the wake region. When moving away from the bodies, streamwise velocity profiles have been influenced by the variation of the rounded corner ratios. The wake region has shrunk owing to the rounded corners, and the drag reduction has been provided. The drag coefficient (CD) has been obtained as 1.418 for r* = 0. As a result of increasing the ratio for the rounded corners, drag coefficients decreased for the square cylinders. The percentage values are 4.6%, 7.2%, 8.4%, 9.6%, 11.1%, 11.9%, 12.5%, 13.3%, and 14.3% for the drag decrement from r* = 0.05 to r* = 0.45 when compared to the reference value. The most effective value for drag reduction has been attained as 4.6% for the ratio of rounded corners in a row. Even though the decrement percentage tends to increase by enhancing the ratio of the rounded corners, the increment rate indicates the decreasing trend.
Citation - WoS: 23
Citation - Scopus: 23
Power Unit Burr-Xii Distribution: Statistical Inference With Applications
(Aip Publishing, 2023) Yıldırım, Elif; İlikkan, Eda Selin; Gemeay, Ahmed M.; Makumi, Nicholas; Bakr, M. E.; Balogun, Oluwafemi Samson
This article introduces a new statistical distribution called the power unit Burr-XII distribution, which is an extension of the Burr XII distribution obtained through a power transform. This paper investigates several statistical properties of this new model, including mode, moments, moment generating and characteristic functions, entropy, and Bonferroni and Lorenz curves. In addition, various classical estimators for the parameters of the power unit Burr-XII distribution are evaluated, including maximum likelihood estimates, ordinary least squares estimates, maximum product of interval estimates, Anderson-Darling, right and left tail Anderson-Darling, and Cramer-von Mises estimators. This study provides tables and graphs to illustrate the performance of these methods under different scenarios and sample sizes. The results of the proposed distribution in different fields of application are shown using the mortality rates of COVID-19 patients in Spain and flood data from 20 observations. As a result of both applications, it was observed that the proposed distribution gave better results compared to other well-known distributions, such as the beta distribution, transformed gamma distribution, log-weighted power distribution, transmuted power distribution, Kumaraswamy distribution, Topp-Leone distribution, exponentiated reduce Kies distribution, and exponentiated Topp-Leone distribution.
Citation - WoS: 7
Citation - Scopus: 7
Reconstruction of Flow Field With Missing Experimental Data of a Circular Cylinder Via Machine Learning Algorithm
(Aip Publishing, 2023) Aksoy, Muharrem Hilmi; Goktepeli, Ilker; İspir, Murat; Cakan, Abdullah
In this study, artificial neural networks (ANNs) have been implemented to recover missing data from the particle image velocimetry (PIV), providing quantitative measurements of velocity fields. Due to laser reflection or lower intensity of particles in the interrogation area, the reconstruction of erroneous velocity vectors is required. Therefore, the distribution of time-averaged and normalized flow characteristics around a circular cylinder has been demonstrated as streamwise and cross-stream velocities at Re = 8000. These velocity components have been given for different regions at x/D = 0.5, x/D = 1.25, x/D = 2, and y/D = 0. These stations have been chosen to estimate missing data for near-wake, mid-wake, far-wake, and symmetry regions. The missing data ratios (A*) for 0.5 <= x/D <= 2 are A* = 3.5%, 7%, and 10%. In addition, these values are A* = 4%, 8%, and 12% for y/D = 0, while A* = 7.5% for the shaded region. The increment of area positively affects the estimation results for near-wake and mid-wake regions. Moreover, the errors tend to decrease by moving away from the body. At y/D = 0, increasing the area negatively influences the prediction of the results. The mean velocity profiles of predicted and experimental data have also been compared. The missing data have been predicted with a maximum percentage error of 3.63% for horizontal stations. As a result, the ANN model has been recommended to reconstruct PIV data.

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