Atmaca, Şükrü Ulaş
Loading...
Profile URL
Name Variants
Atmaca, Ulaş Atmaca, Sukru Ulas Atmaca, Ulas
Job Title
Email Address
suatmaca@ktun.edu.tr
Main Affiliation
02.10. Department of Mechanical Engineering
Status
Current Staff
Website
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Research Topics
Domains
Physical Sciences
Fields
Engineering
Subfields
Mechanical EngineeringComputational MechanicsBiomedical Engineering
Specific Research Areas
Heat Transfer Mechanisms
Fluid Dynamics and Turbulent Flows
Nanofluid Flow and Heat Transfer
Heat Transfer and Optimization
Heat Transfer and Boiling Studies
Sustainable Development Goals
1NO POVERTY
0
Research Products
2ZERO HUNGER
0
Research Products
3GOOD HEALTH AND WELL-BEING
0
Research Products
4QUALITY EDUCATION
0
Research Products
5GENDER EQUALITY
0
Research Products
6CLEAN WATER AND SANITATION
0
Research Products
7AFFORDABLE AND CLEAN ENERGY
1
Research Products
8DECENT WORK AND ECONOMIC GROWTH
0
Research Products
9INDUSTRY, INNOVATION AND INFRASTRUCTURE
0
Research Products
10REDUCED INEQUALITIES
0
Research Products
11SUSTAINABLE CITIES AND COMMUNITIES
0
Research Products
12RESPONSIBLE CONSUMPTION AND PRODUCTION
0
Research Products
13CLIMATE ACTION
0
Research Products
14LIFE BELOW WATER
0
Research Products
15LIFE ON LAND
0
Research Products
16PEACE, JUSTICE AND STRONG INSTITUTIONS
0
Research Products
17PARTNERSHIPS FOR THE GOALS
0
Research Products
This researcher does not have a Scopus ID.
Documents
6
Citations
29
Publication Collaboration
| Affiliation Name | Count |
|---|---|
| Konya Technical University | 10 |
| Selçuk University | 2 |
1 / 1
Data obtained from OpenAlex
Scholarly Output
14
Articles
9
Views / Downloads
41/100
Supervised MSc Theses
3
Supervised PhD Theses
1
WoS Citation Count
26
Scopus Citation Count
33
Patents
0
Projects
0
WoS Citations per Publication
1.86
Scopus Citations per Publication
2.36
Open Access Source
11
Supervised Theses
4
| Journal | Count |
|---|---|
| Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi | 1 |
| Hittite Journal of Science and Engineering | 1 |
| International Journal of Aeroacoustics | 1 |
| International Journal of Civil, Mechanical and Energy Science | 1 |
| Isi Bilimi Ve Teknigi Dergisi/ Journal of Thermal Science and Technology | 1 |
Current Page: 1 / 2
Scopus Quartile Distribution
Competency Cloud
14 results
Scholarly Output Search Results
Now showing 1 - 10 of 14
Article Transient Heat Transfer in Pipes With Time Periodically Changing Boundary Condition(Turk Isı Bilimi ve Teknigi Dernegi, 2018) Altun, A.H.; Ateş, A.; Atmaca, Şükrü Ulaş; Koçak, Sedat; Bilir, Şefik; Atmaca, UlasTransient heat transfer in thermal entrance region of pipes with time periodically changing surface temperature is investigated. The problem is handled in a two-regional pipe for laminar, hydrodynamically developed flow by involving fluid axial conduction. The solution is made numerically by a finite-difference method. A parametric study is done to analyse the effects of Peclet number and angular frequency on heat transfer characteristics. The results show that, considerable amount of heat is diffused back towards the upstream region by axial fluid conduction, which causes preheating the fluid prior to the heated downstream region. The heat transfer characteristics, in all axial positions, including the preheated upstream and the fully developed region, are seen to change periodically in time, similar to the periodic change of the surface temperature in the downstream region. ©2018 TIBTD Printed in Turkey.Other Numerical Examination of Heat Transfer Augmentation Between the Plates With Square Cross-Sectional Ribs for the Staggered Arrangement(2020-11-30) Göktepeli, İlker; Atmaca, Ş. Ulaş; Atmaca, UlasHeat transfer enhancement in the ducts is significantly related with flow separation and reattachment regions. Therefore, ribs are used to obtain the rotational flows in the vicinity of the wall since the fluctuations in the thermal and hydrodynamic boundary layers are effective for the increment of heat transfer by convection. Even though heat transfer surface area is enlarged by placing the ribs into the channels, the pressure loss due to the ribs has to be taken into account and controlled in these systems. Based on the aforementioned explanations, the square cross-sectional ribs have been mounted on the bottom and the top walls of horizontal parallel plates in terms of staggered arrangement. In the present paper, numerical analyses have been conducted via k-? SST turbulence model at Re = 10000, 15000 and 20000 for different spacing values between two successive ribs. For the constant rib dimensions, the ribbed models have been compared by referring to smooth plates as reference model. For this reason; time-averaged results including streamwise velocity components, temperature distributions, pressure values, streamline patterns and Nusselt numbers for the ribbed and the smooth plates have been separately presented and compared. Heat transfer has been enhanced due to the ribs deforming the hydrodynamic and thermal boundary layers. Furthermore, increasing the rib spacing and Reynolds number has enhanced Nusselt number. As observed, heat transfer has also been augmented by extending the distance between two successive ribs since fluid easily penetrates to the sink between them for the production of recirculation regions. However, in case of the ribbed models, there are gradual drop pressure values along the channel. For this reason, the rib effect on these values is much more as evidently observed at Re = 10000.Article The Effects of Nanofluids on Forced Convection Heat Transfer Inside Parallel Plate Heated With Flush Mounted Discrete Heater Sources(2023) Atmaca, Şükrü Ulaş; Göktepeli, İlker; Ateş, AliA numerical solution on forced convection of Al2O3-water nanofluid for different volume fractions is investigated for laminar flow through a parallel plate with flush mounted discrete heat sources. The model used for nanofluid mixture is a single-phase approach and fluid properties are considered constant with temperature. The finite difference method is used for solutions and four different volume fractions are considered varying from 0% to 4%. A fully developed laminar velocity profile is considered and the parallel plate is assumed as heated with three discrete heat sources flush mounted to the top and bottom plate with the same lengths. Uniform wall temperature boundary condition is taken for discrete heaters. Peclet numbers are in the range of 20-100. For comparison and validity of the solution the results for a classical problem, laminar flow through a parallel plate which is heated at the downstream region with constant temperature, are obtained. Results are presented in terms of bulk temperature, heat flux, and local Nusselt number. Heat transfer is enhanced with the particle volume concentration. For comparison, pure water results are also shown in the figures. At the locations where heat is applied the heat flux values decrease as the volume fraction increase and the bulk temperature values are higher for the higher volume fractions at the heated locations. As the volume fraction increases the local Nusselt number can increase up to 30% than to pure water.Article Citation - WoS: 9Citation - Scopus: 9Visualization of Flow Characteristics Between the Ribbed Plates Via Particle Image Velocimetry(VINCA INST NUCLEAR SCI, 2021) Göktepeli, İlker; Atmaca, Şükrü Ulaş; Yağmur, Sercan; Atmaca, UlasHeat transfer is considerably influenced by flow stagnation, separation and reattachment regions due to the ribbed plates. Placing the ribs such as fins, turbulators that trigger the flow separation, enhances the heat transfer inside the channel by increasing the turbulence intensity. The flow separation is caused by disturbing the thermal and hydrodynamic development lengths. Moreover, these ribs also make an impact that increases the heat transfer by enlarging the heat transfer area. However, the ribs lead to the increment of the required pumping power in the meantime due to the increasing pressure loss in such systems. This aforementioned method is used for the heat exchangers, the solar collectors, the cooling of electronic devices. The investigation of the flow characteristics is very crucial to understand the heat transfer mechanism in the ducts for this reason. In the present paper, the flow characteristics between the plates have been experimentally researched. Particle image velocimetry system in the open water channel of Selcuk University Advanced Technology Research and Application Center has been used. The smooth plates have been taken as the reference model and used for the comparison with the plates having the rectangular cross-sectional ribs. The ribs with various heights of 0.1 < h' = h/H <= 0.3 have been symmetrically placed on the internal surfaces of the plates via several spacing values of 0.5 <= S' = S/H <= 1 for varying Reynolds numbers as 10000 <= Re <= 20000. As a result, the flow characteristics have been given in terms of the contour graphics for velocity vector field, velocity components and vorticity.Master Thesis Çevresine Üçgen Kanatçıklar Yerleştirilmiş Silindirlerden Doğal Taşınım Isı Transferi(Konya Teknik Üniversitesi, 2020) Koy Koy, Amisi; Atmaca, Şükrü UlaşBu tez çalışmasında alüminyum bir silindir çevresine takılan farklı sayıda ve farklı yüksekliklerdeki üçgen şeklindeki kanatçıkların doğal taşınım ısı transferi incelenmiştir. Kanatçıklar silindirin çevresine sık durum olan 18, orta sıklık olan 12 adet ve seyrek olarak 6 adet olarak takılmışlardır. Deneylerde 12 cm uzunluğundaki silindir üzerine diğer dik kenarı 12, 6 ve 3 cm olan üçgen şeklinde kanatçıklar takılmıştır. Deney numunesi 45° lik açılar yapacak şekilde 7 farklı konumda yerleştirilmiştir. Silindik deney numunesinin merkezine elektrikli rezistans ile sabit ısı akısı uygulanmış ve yine silindirin iç yüzeyine yerleştirilen termokupllar ile sıcaklıklar ölçülmüştür. Sonuçlar Nusselt sayısının Rayleigh sayısı ile değişimi olarak verilmiştir. Deney sonuçlarına göre kanatçık ile düz silindire göre ısı geçişi önemli oranda artmaktadır. Ayrıca kanatçık sayısının ve kanatçık yüksekliğinin artması da ısı transferini arttırmaktadır. Çevresel kanat sıklığının artırılması ısı transferi oranını beklenen oranda arttırmamıştır. Genel olarak silindir düşey konumda iken (90° ve 270°) ısı transferinin arttığı belirlenmiştir.Article Numerical Modeling of Backward-Facing Step Flow Via Computational Fluid Dynamics(2023-09-30) Göktepelı, Ilker; Atmaca, UlaşAs a fundamental case for problems of fluid mechanics, examination of flow separation and its reattachment is important for engineering applications. Considering the significance of the subject, backward-facing step flow has been modeled via Computational Fluid Dynamics (CFD) based on an experimental study previously done at Re = 5000. Steady simulations have been conducted by k-ε Renormalization Group (RNG) considering the same flow conditions of the reference study. Pressure distributions, streamwise and cross-stream velocity components, velocity magnitude values with streamline patterns and turbulence kinetic energy values have been presented by using contour graphics. Furthermore, the stations for pressure distributions, velocity profiles for streamwise components and turbulence kinetic energy values have been defined for evolution of related data. Lower pressure zone for the wake region of the backward-facing step has been attained due to flow separation. Separation of the upstream boundary layer has been seen and it became a curved one. Moreover, turbulence level of the step wake has been obtained as higher than those of any other points. Transition to core flow has been attained at y* = 1.1 that is above the step height. Flow oscillations have been observed for x* ≥ 2 and y* ≤ 1 since the fluctuations for these values were effective in the wake region. To sum up, the dimensionless reattachment length has been numerically obtained as 5.92 which is very good agreement with the experimental results at same Reynolds number. The deviation from the reference results is from 0.34 % to 1.33 %.Article Citation - WoS: 3Citation - Scopus: 5Examination of Air Flow Characteristics Over an Open Rectangular Cavity Between the Plates(Sage Publications Inc, 2023-06-01) Göktepeli, İlker; Atmaca, UlaşAir flow characteristics of an open cavity have been numerically examined by using different turbulence models of Detached Eddy Simulation (DES), k-& epsilon; Realizable, k-& omega; Shear Stress Transport (SST) and Large Eddy Simulation (LES) based on an experimental study of open literature. Numerical results of transient analyses have been compared to experimental results at cavity length-based Reynolds number of Re = 4600. Pressure distributions, streamline patterns, streamwise velocity components, mean velocity values and their vectors have been given in terms of contour graphics. Moreover, velocity profiles have been presented. Pressure fluctuations have been triggered by flow separation and its reattachment. Due to upstream separation of boundary layer, there was curved boundary layer obtained between the outer potential-flow-like and the recirculation zones. As a result, negative velocity values are evidence for rotational flows affected by formation of secondary flows in the cavity. Furthermore, lower pressure region has been observed as a result of rotational flow which was powerful in the open cavity. Numerical results of DES and LES turbulence models are in good agreement with the results of reference study. As the numerical results obtained by LES turbulence model are approximately same with those of experimental reference study, LES turbulence model is mostly recommended. As an option to these turbulence models, k-& omega; SST model could be utilized for limited computer capacity. However, k-& epsilon; Realizable model is not sufficient for capturing rotational flows which are very effective in terms of present case.Article Effects of Mass Flow Rate and Equivalence Ratio on Laminar Premixed Methane Air Flame(2021-03-31) Atmaca, Şükrü Ulaş; Atmaca, UlasThe structures of laminar premixed flames of methane air mixture are investigated for different equivalence ratios and different mass fluxes numerically. Equivalence ratio values are taken as 0.6, 1 and 1.4 that can be seen in engineering applications. These values correspond to lean, stoichiometric and rich methane-air mixtures respectively. CHEMKIN 19 program and GRI-Mech 3.0 mechanism are used for numerical solution. The axial velocity and mole fractions of CH4 and O2 as reactants, and mole fractions of H2O, CO, CO2 and H2 as products are investigated for each runs. It is found that with the increase of the mass flow rate; the axial velocities of the flame, the axial location of the reaction zones and the mole fraction values of the intermediates increases. The values of the mole fractions of the reactants do not change with mass flux.Master Thesis Türbülanslı Akışta Ondüleli Kanallarda Akış ve Isı Transferi Karakteristikleri(Konya Teknik Üniversitesi, 2019) Shareef, Mustafa Noaman; Atmaca, Şükrü UlaşYatay paralel iki plakanın alt ve üst yüzeylerine akış yapısını bozmak için V şeklinde ondüleler yerleştirilmiştir. V şeklindeki ondülelerin ısı transferi ve akış karakteristiklerine etkilerini inceleme için hem sayısal hem de deneysel bir çalışma yapılmıştır. Kanalın alt ve üst cidarlarının sıcaklığı 400 K 'de sabit tutulurken, akışkanın 300 K'de sisteme girdiği kabul edilmiştir. Ayrıca bu aralıkta akışkanın faz değiştirmediği kabul edilmiştir. V şeklindeki ondülelerin yükseklikleri H=15 mm alınmıştır ve tepe açıları ? = 60°, 100° ve 140° olmak üzere üç farklı açıda değiştirilmiştir. Türbülanslı akış için Reynolds sayısı 10000, 15000 ve 20000 değerleri alınmıştır. Sonuçların karşılaştırması amacıyla aynı Reynolds sayısı değerleri düz plaka için tekrarlanmıştır. Çalışmanın sayısal kısmında hesaplamalı Akışkanlar Dinamiği analiz programı kullanılmıştır. Sayısal çalışmanın ilk kısmında süreklilik, momentum ve enerji denklemleri beraber ele alınmıştır. İkinci aşamada ise enerji denklemi çözülmeden bahsedilen denklemlerle yalnızca akış karakteristikleri saptanmıştır. Çalışmanın deneysel kısmında ise su tünelinde Parçacık Görüntülemeli Akış Ölçümü yöntemi ile akış karakteristikleri elde edilmiştir. Sonuç olarak kanala ondüle yerleştirilmesi ile ısı transferi düz plakaya göre önemli oranda arttırdığı görülmüştür. Ayrıca Reynolds sayısının artması ile gerçekleşen ısı transferi de artmıştır. Ayrıca Reynolds sayısının artışı ile yüzey sürtünme katsayısı değerlerinin azaldığı saptanmıştır.Doctoral Thesis Mikrokanallarda Nanoakışkanlar için Laminer Akışta Geçici Rejim Birleşik Isı Transferi Problemi(Konya Teknik Üniversitesi, 2024) Göktepeli̇, İlker; Atmaca, Şükrü UlaşMevcut tez çalışması kapsamında mikrokanaldaki laminer akışta nanoakışkanların ısıl performansa etkisi geçici rejim problemiyle sayısal olarak ele alınmıştır. Temel akışkan olarak suya farklı hacimsel konsantrasyon değerlerinde ( = % 1, % 4 ve % 7), ayrı ayrı olmak üzere Al2O3, CuO ve TiO2 nanoparçacıkların eklendiği durumlar ara yüzey ısı akısı, ara yüzey sıcaklığı, yığık sıcaklık ve radyal sıcaklık gibi ısı transferi karakteristikleri bakımından karşılaştırılmıştır. Bu bağlamda her bir nanoparçacık için açık literatürdeki iki farklı termofiziksel özellik modeli de kıyaslanmıştır. Buna göre sayısal çözüme Peclet sayısının (Pe = 1, 5, 20 ve 50), cidar kalınlık oranının (d' = 0.02, 0.1, 0.2, 0.3, 0.6, 1 ve 1.4), ısıl yayılım katsayısı oranının (αw-nf = 0.1, 1 ve 10), ısı iletim katsayısı oranının (kw-nf = 0.1, 1 ve 10) ve Brinkman sayısının (Br = -0.2, -0.1, 0, 0.1 ve 0.2) etkisi değerlendirilmiştir. Eksenel iletimin düşük Peclet sayılarında daha etkili olduğu ve Pe ≥ 20 için bu değerin ısı transferini önemli ölçüde etkilemediği gözlemlenmiştir. Cidar kalınlık oranındaki artışın ve ısı iletim katsayısı oranındaki azalışın ısı transferini azaltıcı yönde etkilediği görülmüştür. Isıl yayılım katsayısı oranının değişimi parametrik anlamda oldukça etkisiz kalmıştır. Viskoz yitim tesirini gösteren Brinkman sayısının sıfırdan farklı olduğu değerlerde ısı transferi yönü önemli ölçüde değişmiştir. Belirtilen parametrelerin değeri yükseldikçe sürekli rejime ulaşma süresi düşme eğilimi göstermiştir. Burada temel akışkan su için belirtilen durumlar nanoakışkanlar için de geçerlidir. Nanoakışkan için hacimsel konsantrasyon değerinin artışı ile ısı transferi de artmıştır. Nanoparçacık etkisi açısından sırasıyla CuO, Al2O3 ve TiO2, sabit hacimsel konsantrasyon değerinde daha fazla ısıl performans artışını sağlamıştır. Her bir nanoparçacık için karşılaştırılan termofiziksel özellik modellerine göre birbirine en yakın sonucu Al2O3 nanoparçacığına ait modeller sunmuştur. Ancak diğer nanoparçacıklar için birer modelin bu anlamda yetersiz kaldığı gözlemlenmiştir.