Cemil Yiğit - Academia.edu (original) (raw)

Papers by Cemil Yiğit

Research paper thumbnail of Sıcak yüzeylerin sprey ile soğutulmasının sayısal incelenmesi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun... more 06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Günümüzde giderek artan bir oranda endüstriyel proseslerde su sisi kullanımı yaygınlaşmaktadır. Su sisi 100 µm çapında ve daha küçük su damlacıkları içerir ve damlacıklar hava akışıyla birlikte taşınırlar. Su sisi spreyinin sıvı kütle akısı düşük olduğu için ısı transferi geleneksel su spreyleri kadar yüksek değildir. Ancak daha üniform bir sıcaklık dağılımı elde edilir ve su kullanım verimlilikleri nispeten yüksektir.Bu Çalışmada, atmosferik koşullarda yüksek sıcaklıktaki yüzeylerin soğutulması için hem hava hem de su sisi spreyi sayısal olarak modellenmiştir. Sayısal çözüm koşulları şöyledir; su damlacıklarını taşıyan hava hızı 0 m/s ile 50.29 m/s, sıvı...

Research paper thumbnail of Makinelerde titreşim analizi yöntemiyle uyarıcı bakım

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun... more 06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Uyarıcı bakım Sanayiinin gelişmesiyle insanların hayallerini süsleyen idealler gerçekleşmeye başlamıştır. Ancak buda beraberinde bazı sorunları getirdi. İlk zamanlar, tecrübeli işletme mühendisleri, bir makinenin düzgün çalışıp çalışmadığını ve arızaların meydana çıkıp çıkmadığını, dokunarak ve işiterek anlayabilirlerdi. Günümüzde bu şekilde yapılan kontrollere güvenilemez. Çünkü, işin içine insan faktörü girdiği zaman hata yapma riski her zaman yüksek bir orandadır ve modern makinelerin meydana çıkardıkları titreşimler yüksek frekansta olduklarından, bunların ölçülmesinde ve meydana çıkarılmasında aygıtlara gereksinim vardır. Bilindiği üzere titreşim, aş...

Research paper thumbnail of Wind Turbine Blade Design with Computational Fluid Dynamics Analysis

Although there are many blade profile have been improved for use in aviation and energy sector, t... more Although there are many blade profile have been improved for use in aviation and energy sector, there is still needed blade profiles which have higher performance especially the commercial horizontal axis wind turbine efficiency is taken into account. The purpose of this study is to obtain the new blade profiles which have higher lift (CL) and drag (CD) coefficients for wind turbine making geometric modifications on several NACA wing profile systematically. For this purpose, the performance of NACA and developed new profiles have been compared with each other using computational fluid dynamics analysis and it is seen that the new developed profiles have higher performance than NACA profiles. Later on, according to the Blade Element Momentum Theory (BEM Theory) turbine blades are designed with developed new profiles and 3-dimensional CFD analyses are performed. Increase in torque in the wind turbine is determined.

Research paper thumbnail of Optimization of the S-Rotor Savonius Wind Turbine

Sakarya University Journal of Science, 2020

In this study, 2D Computational Fluid Dynamics (CFD) model was used to investigate the optimum wo... more In this study, 2D Computational Fluid Dynamics (CFD) model was used to investigate the optimum working conditions of the S-Rotor Savonius (S-RS) wind turbine and to determine the most suitable geometry. The CFD model has been validated by studies on the S-RS wind turbine in the literature. The sliding mesh method which uses a mesh motion was utilized to perform the numerical study. CFD analysis was carried out under various tip-speed ratio at 4 m/s airspeed for the S-RS wind turbine which has a frontal swept area of approximately 0.3 m 2. Within the scope of the optimization study, aspect-ratio (AR) and overlap ratio (OR) of the S-RS wind turbine's rotor in the fixed frontal swept area were taken as parameters. The geometry of the S-rotor has been optimized using the Ansys/Response Surface Optimization (RSO) tool. Under the constraints in which the optimization study was carried out, aerodynamic efficiency was obtained as %22.19 at 0.848 AR and 0.068 OR. This yield is significant when the efficiency of S-RS's wind turbine is taken into consideration.

Research paper thumbnail of Improving the Horizontal Axis Wind Turbine Blade Profiles

Sakarya University Journal of Science, 2018

Due to greenhouse gases, we feel the effects of global warming more and more every day, so we nee... more Due to greenhouse gases, we feel the effects of global warming more and more every day, so we need far more efficient Horizontal Axis Wind Turbines (HAWTs). This study was carried out to develop turbine blades with higher momentum coefficient (Cm) for the HAWTs. For this purpose, the blade profile that has higher performance was improved using Taguchi and Computational Fluid Dynamics (CFD) methods. With reference to the NACA 0012 profile, changing the upper and lower cambers of the profile derived the new blade profiles. Using the Taguchi method, the optimum blade profile with a maximum Cm coefficient was obtained. After the profile to be used on the turbine blades is determined, the blades are designed with the Blade Element Momentum (BEM) theory. A 3dimensional model for the HAWTs is developed using ANSYSv.16.2/Fluent Software. CFD analyses were performed using a sliding mesh approach to get more realistic and reliable results and to gain more knowledge of the performance. Numerical analysis results show that power coefficient (Cp) of the optimum profile is increased by 7.42% according to the NACA 0012 profile.

Research paper thumbnail of CFD modeling of carbon combustion and electrode radiation in an electric arc furnace

Applied Thermal Engineering, 2015

h i g h l i g h t s 3D-CFD of carbon combustion and electrode radiation were performed for an EAF... more h i g h l i g h t s 3D-CFD of carbon combustion and electrode radiation were performed for an EAF. Particles surface and gas phase reactions used to predict coal particle combustion. Realistic temperature distribution obtained for slag surface. Temperature, CO and CO 2 distribution of carbon combustion visually obtained.

Research paper thumbnail of Multiphase Spray Cooling of Steel Plates Near the Leidenfrost Temperature — Experimental Studies and Numerical Modeling

Atomization and Sprays, 2010

Experimental studies were conducted to reveal the heat transfer mechanism of impacting water mist... more Experimental studies were conducted to reveal the heat transfer mechanism of impacting water mist on high-temperature surfaces. A numerical model was developed to simulate, for atmospheric applications, air and water mist spray cooling of surfaces heated to temperatures ranging from nucleate to film boiling. Local heat transfer coefficients were measured in the film-boiling regime at various air velocities and liquid mass fluxes. The test conditions of water mist cover the variations of air velocity from 0 to 50.3 m/s, liquid mass flux from 0 to 7.67 kg/m 2 s, and surface temperature of stainless steel between 525 • C and 500 • C. Radial heat transfer distributions were measured at different liquid mass fluxes. The tests revealed that the radial variation of heat transfer coefficients of the water mist has a similar trend to that of air jet cooling. At the stagnation point, the heat transfer coefficient increases with both the air velocity and the liquid mass flux. The convective air heat transfer is consistent with the published correlation in the literature. The heat transfer contribution due to the presence of water increases almost linearly with the liquid mass flux. For dilute sprays, the total heat transfer coefficient can be established as two separable effects, which is the summation of the heat transfer coefficient of air and of liquid mass flux. This study shows that with a small amount of water added in the impacting air jet, the heat transfer is dramatically increased. The Leidenfrost temperature associated with the water mist cooling was also measured. The Leidenfrost temperature increased with both the air velocity and the liquid mass flux. The model simulation was compared against available test data at atmospheric conditions, and the simulation compared favorably well with the test data.

Research paper thumbnail of Effect of Two-Dimensional Profile Optimization on Vertical Axis Wind Turbine Power Performance

Tehnicki vjesnik - Technical Gazette, 2021

In this study, performance of the blade profiles which was developed numerically and parametrical... more In this study, performance of the blade profiles which was developed numerically and parametrically was examined experimentally for vertical axis wind turbine. In the parametric optimization study, angle of attack, mean (camber) line and thickness were taken as parameter, and the profile was optimized by using Ansys/Response Surface Optimization tool. After that, in the numerical optimization study, the lift and drag coefficients were taken as parameters and the profile was optimized and the blade profiles of NACA0012-α and NACA0012-β, which would make the lift-to-drag ratio maximum, were obtained. The developed profiles were produced by 3D printer and the power data was measured experimentally for 3, 4 and 5 bladed turbines. The highest power was obtained in the 4-bladed turbine for all profiles. The power coefficient of 0.19 was obtained from a reference profile, while power coefficient of 0.24 was obtained from NACA0012-α profile and 0.30 from NACA0012-β profile. The blade profile derived by numerical optimization reached 25% higher power coefficient than the blade profile derived by parametric optimization. It is found that lift coefficient on the power coefficient of the vertical axis wind turbine is more dominant than the drag coefficient.

Research paper thumbnail of Effect of Two-Dimensional Profile Optimization on Vertical Axis Wind Turbine Power Performance

Tehnički Vjesnik, 2021

In this study, performance of the blade profiles which was developed numerically and parametrical... more In this study, performance of the blade profiles which was developed numerically and parametrically was examined experimentally for vertical axis wind turbine. In the parametric optimization study, angle of attack, mean (camber) line and thickness were taken as parameter, and the profile was optimized by using Ansys/Response Surface Optimization tool. After that, in the numerical optimization study, the lift and drag coefficients were taken as parameters and the profile was optimized and the blade profiles of NACA0012-α and NACA0012-β, which would make the lift-to-drag ratio maximum, were obtained. The developed profiles were produced by 3D printer and the power data was measured experimentally for 3, 4 and 5 bladed turbines. The highest power was obtained in the 4-bladed turbine for all profiles. The power coefficient of 0.19 was obtained from a reference profile, while power coefficient of 0.24 was obtained from NACA0012-α profile and 0.30 from NACA0012-β profile. The blade profil...

Research paper thumbnail of Sıcak yüzeylerin sprey ile soğutulmasının sayısal incelenmesi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun... more 06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Günümüzde giderek artan bir oranda endüstriyel proseslerde su sisi kullanımı yaygınlaşmaktadır. Su sisi 100 µm çapında ve daha küçük su damlacıkları içerir ve damlacıklar hava akışıyla birlikte taşınırlar. Su sisi spreyinin sıvı kütle akısı düşük olduğu için ısı transferi geleneksel su spreyleri kadar yüksek değildir. Ancak daha üniform bir sıcaklık dağılımı elde edilir ve su kullanım verimlilikleri nispeten yüksektir.Bu Çalışmada, atmosferik koşullarda yüksek sıcaklıktaki yüzeylerin soğutulması için hem hava hem de su sisi spreyi sayısal olarak modellenmiştir. Sayısal çözüm koşulları şöyledir; su damlacıklarını taşıyan hava hızı 0 m/s ile 50.29 m/s, sıvı...

Research paper thumbnail of Makinelerde titreşim analizi yöntemiyle uyarıcı bakım

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun... more 06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Uyarıcı bakım Sanayiinin gelişmesiyle insanların hayallerini süsleyen idealler gerçekleşmeye başlamıştır. Ancak buda beraberinde bazı sorunları getirdi. İlk zamanlar, tecrübeli işletme mühendisleri, bir makinenin düzgün çalışıp çalışmadığını ve arızaların meydana çıkıp çıkmadığını, dokunarak ve işiterek anlayabilirlerdi. Günümüzde bu şekilde yapılan kontrollere güvenilemez. Çünkü, işin içine insan faktörü girdiği zaman hata yapma riski her zaman yüksek bir orandadır ve modern makinelerin meydana çıkardıkları titreşimler yüksek frekansta olduklarından, bunların ölçülmesinde ve meydana çıkarılmasında aygıtlara gereksinim vardır. Bilindiği üzere titreşim, aş...

Research paper thumbnail of Wind Turbine Blade Design with Computational Fluid Dynamics Analysis

Although there are many blade profile have been improved for use in aviation and energy sector, t... more Although there are many blade profile have been improved for use in aviation and energy sector, there is still needed blade profiles which have higher performance especially the commercial horizontal axis wind turbine efficiency is taken into account. The purpose of this study is to obtain the new blade profiles which have higher lift (CL) and drag (CD) coefficients for wind turbine making geometric modifications on several NACA wing profile systematically. For this purpose, the performance of NACA and developed new profiles have been compared with each other using computational fluid dynamics analysis and it is seen that the new developed profiles have higher performance than NACA profiles. Later on, according to the Blade Element Momentum Theory (BEM Theory) turbine blades are designed with developed new profiles and 3-dimensional CFD analyses are performed. Increase in torque in the wind turbine is determined.

Research paper thumbnail of Optimization of the S-Rotor Savonius Wind Turbine

Sakarya University Journal of Science, 2020

In this study, 2D Computational Fluid Dynamics (CFD) model was used to investigate the optimum wo... more In this study, 2D Computational Fluid Dynamics (CFD) model was used to investigate the optimum working conditions of the S-Rotor Savonius (S-RS) wind turbine and to determine the most suitable geometry. The CFD model has been validated by studies on the S-RS wind turbine in the literature. The sliding mesh method which uses a mesh motion was utilized to perform the numerical study. CFD analysis was carried out under various tip-speed ratio at 4 m/s airspeed for the S-RS wind turbine which has a frontal swept area of approximately 0.3 m 2. Within the scope of the optimization study, aspect-ratio (AR) and overlap ratio (OR) of the S-RS wind turbine's rotor in the fixed frontal swept area were taken as parameters. The geometry of the S-rotor has been optimized using the Ansys/Response Surface Optimization (RSO) tool. Under the constraints in which the optimization study was carried out, aerodynamic efficiency was obtained as %22.19 at 0.848 AR and 0.068 OR. This yield is significant when the efficiency of S-RS's wind turbine is taken into consideration.

Research paper thumbnail of Improving the Horizontal Axis Wind Turbine Blade Profiles

Sakarya University Journal of Science, 2018

Due to greenhouse gases, we feel the effects of global warming more and more every day, so we nee... more Due to greenhouse gases, we feel the effects of global warming more and more every day, so we need far more efficient Horizontal Axis Wind Turbines (HAWTs). This study was carried out to develop turbine blades with higher momentum coefficient (Cm) for the HAWTs. For this purpose, the blade profile that has higher performance was improved using Taguchi and Computational Fluid Dynamics (CFD) methods. With reference to the NACA 0012 profile, changing the upper and lower cambers of the profile derived the new blade profiles. Using the Taguchi method, the optimum blade profile with a maximum Cm coefficient was obtained. After the profile to be used on the turbine blades is determined, the blades are designed with the Blade Element Momentum (BEM) theory. A 3dimensional model for the HAWTs is developed using ANSYSv.16.2/Fluent Software. CFD analyses were performed using a sliding mesh approach to get more realistic and reliable results and to gain more knowledge of the performance. Numerical analysis results show that power coefficient (Cp) of the optimum profile is increased by 7.42% according to the NACA 0012 profile.

Research paper thumbnail of CFD modeling of carbon combustion and electrode radiation in an electric arc furnace

Applied Thermal Engineering, 2015

h i g h l i g h t s 3D-CFD of carbon combustion and electrode radiation were performed for an EAF... more h i g h l i g h t s 3D-CFD of carbon combustion and electrode radiation were performed for an EAF. Particles surface and gas phase reactions used to predict coal particle combustion. Realistic temperature distribution obtained for slag surface. Temperature, CO and CO 2 distribution of carbon combustion visually obtained.

Research paper thumbnail of Multiphase Spray Cooling of Steel Plates Near the Leidenfrost Temperature — Experimental Studies and Numerical Modeling

Atomization and Sprays, 2010

Experimental studies were conducted to reveal the heat transfer mechanism of impacting water mist... more Experimental studies were conducted to reveal the heat transfer mechanism of impacting water mist on high-temperature surfaces. A numerical model was developed to simulate, for atmospheric applications, air and water mist spray cooling of surfaces heated to temperatures ranging from nucleate to film boiling. Local heat transfer coefficients were measured in the film-boiling regime at various air velocities and liquid mass fluxes. The test conditions of water mist cover the variations of air velocity from 0 to 50.3 m/s, liquid mass flux from 0 to 7.67 kg/m 2 s, and surface temperature of stainless steel between 525 • C and 500 • C. Radial heat transfer distributions were measured at different liquid mass fluxes. The tests revealed that the radial variation of heat transfer coefficients of the water mist has a similar trend to that of air jet cooling. At the stagnation point, the heat transfer coefficient increases with both the air velocity and the liquid mass flux. The convective air heat transfer is consistent with the published correlation in the literature. The heat transfer contribution due to the presence of water increases almost linearly with the liquid mass flux. For dilute sprays, the total heat transfer coefficient can be established as two separable effects, which is the summation of the heat transfer coefficient of air and of liquid mass flux. This study shows that with a small amount of water added in the impacting air jet, the heat transfer is dramatically increased. The Leidenfrost temperature associated with the water mist cooling was also measured. The Leidenfrost temperature increased with both the air velocity and the liquid mass flux. The model simulation was compared against available test data at atmospheric conditions, and the simulation compared favorably well with the test data.

Research paper thumbnail of Effect of Two-Dimensional Profile Optimization on Vertical Axis Wind Turbine Power Performance

Tehnicki vjesnik - Technical Gazette, 2021

In this study, performance of the blade profiles which was developed numerically and parametrical... more In this study, performance of the blade profiles which was developed numerically and parametrically was examined experimentally for vertical axis wind turbine. In the parametric optimization study, angle of attack, mean (camber) line and thickness were taken as parameter, and the profile was optimized by using Ansys/Response Surface Optimization tool. After that, in the numerical optimization study, the lift and drag coefficients were taken as parameters and the profile was optimized and the blade profiles of NACA0012-α and NACA0012-β, which would make the lift-to-drag ratio maximum, were obtained. The developed profiles were produced by 3D printer and the power data was measured experimentally for 3, 4 and 5 bladed turbines. The highest power was obtained in the 4-bladed turbine for all profiles. The power coefficient of 0.19 was obtained from a reference profile, while power coefficient of 0.24 was obtained from NACA0012-α profile and 0.30 from NACA0012-β profile. The blade profile derived by numerical optimization reached 25% higher power coefficient than the blade profile derived by parametric optimization. It is found that lift coefficient on the power coefficient of the vertical axis wind turbine is more dominant than the drag coefficient.

Research paper thumbnail of Effect of Two-Dimensional Profile Optimization on Vertical Axis Wind Turbine Power Performance

Tehnički Vjesnik, 2021

In this study, performance of the blade profiles which was developed numerically and parametrical... more In this study, performance of the blade profiles which was developed numerically and parametrically was examined experimentally for vertical axis wind turbine. In the parametric optimization study, angle of attack, mean (camber) line and thickness were taken as parameter, and the profile was optimized by using Ansys/Response Surface Optimization tool. After that, in the numerical optimization study, the lift and drag coefficients were taken as parameters and the profile was optimized and the blade profiles of NACA0012-α and NACA0012-β, which would make the lift-to-drag ratio maximum, were obtained. The developed profiles were produced by 3D printer and the power data was measured experimentally for 3, 4 and 5 bladed turbines. The highest power was obtained in the 4-bladed turbine for all profiles. The power coefficient of 0.19 was obtained from a reference profile, while power coefficient of 0.24 was obtained from NACA0012-α profile and 0.30 from NACA0012-β profile. The blade profil...