Abdi Kukner | Istanbul Technical University (original) (raw)

Papers by Abdi Kukner

2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021

Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in ai... more Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in air pollution is also striking drive to switch fuel-sourced metrobusses into electric ones. Therefore, according to Istanbul's promising potential with long Bus Rapid Transit Systems (BRT) and existing problem with high levels of air pollutants, integration of Electric Bus Rapid Transit System (e-BRT) offers a core solution. This study is the preliminary feasibility analysis of e-BRT for the longest round-route of Sogutlucesme-Beylikduzu (SB-BS), Istanbul, Turkey. For e-BRT adaptation, two actively on service metrobus models of Mercedes Benz™ are selected as 18-m-long Conecto G with 150 passenger and 21-m-long CapaCity L with 191-passenger. Real-time 3-axis acceleration, 3-axis magnetometer, latitude, longitude and barometric height measurements on the selected round-route of SB-BS under dynamic passenger load are collected and analyzed. 3D-accelerometer measurements are filtered with 8th order low-pass and high-pass Butterworth filters with respective cut-off frequencies of 4.5 Hz and 100 Hz prior to each integration, FFT, Periodogram, PSD, Welch-PSD and RMS analysis on MATLAB. The major purpose of acceleration measurements is to form a reference energy state of current fuel-sourced BRT so that future e-BRT system can be compared and feasibility of e-BRT can be conducted. Meanwhile, magnetometer measurements are performed to form a comparison with future e-BRT system. This will allow to detect higher existing magnetic field in e-metrobus so that necessary precautions can be taken for passenger safety. Finally, latitude, longitude and barometric height measurements are collected in order to map 3D route, inclines and maneuvering locations and to provide additional information on results of acceleration analyses. Moreover, to detect the most challenging route that e-BRT need to cover, maximum energy consuming route is extracted upon collected and analyzed current BRT measurements. All comparisons are performed upon requested original fuel-sourced BRT on active service durations and on the exact date of the measurements. Results indicate that the energy dissipation is maximum on CapaCity L at rear seat without suspension on Beylikduzu-Sogutlucesme (BS) route direction. Statistically, required energy need to cover SB route is greater than BS due to steep inclines. It is found that 37.5% of displacement power is stored in suspension systems. Reported peak magnetic field of electric vehicles is greater than BRT of Istanbul by only 98 µT.

Gemi ve deniz teknolojisi, Feb 7, 2017

The reliable Renewable Energy Systems development is being a primary topic in several research ar... more The reliable Renewable Energy Systems development is being a primary topic in several research areas. This reliability can be achieved chiefly based on the right choice of the used development technology. At the present time, the power is obtained from conventional and renewable energy. Conventional power is produced from fosil fuels. The power obtained from renewable energy is the renewable power considered includes photovoltaic(PV), wind, and concentrated solar power (CSP). Moreover, renewable power usually uses local natural resources and encourages local manufacturing capabilities since fossil fuels are being depleted and nuclear power is not really safe. The power generation from renewable energy is getting more and more attention at the global level. In this study, alternative energy systems and applications to the yachts had been investigated. A detailed description of the system had been explained how to obtain the daily energy to be needed and usage in yacht by harnessing renewable energy from the wind and the Sun.

... Supplemental Notes: ABDI KUKNER OTHER PHYS. DESCRIPTION: XI CHARTS THESIS PH. ... University ... more ... Supplemental Notes: ABDI KUKNER OTHER PHYS. DESCRIPTION: XI CHARTS THESIS PH. ... University Microfilms International. 300 North Zeeb Road Ann Arbor, MI 48106 USA. Available from UC Berkeley Transportation Library through interlibrary loan or document delivery. ...

Ocean Engineering, Feb 1, 2017

Three wave energy converter arrays are analyzed to investigate the effects of the wave-body inter... more Three wave energy converter arrays are analyzed to investigate the effects of the wave-body interactions on the energy generation within arrays. The arrays are analyzed by modeling four sea states observed at each of two locations in the Turkish coasts of the Black Sea. A potential flow based solver which was formerly developed for the analysis of the ship motions has been modified to analyze the interaction of multiple bodies in time domain. A high pressure hydraulic power takeoff system is employed for converting the mechanical force and motion provided by the float of the wave energy converter. The results show that the energy generated by each wave energy converter in all arrays is less than that generated by a single isolated wave energy converter in both locations with all sea states. The amount of reduction in the energy generated diminishes with the sea states become more severe. While the amounts of energy generated by the wave energy converters in Array 1 and 2 are close to each other, the hydrodynamic interaction of multiple wave energy converters become more severe in Array 3 and the amount of the energy generated by each wave energy converter differ from one another significantly.

Journal of Naval Sciences and Engineering, Apr 1, 2014

The power takeoff systems consisted in wave energy converters are studied in this paper. Wave ene... more The power takeoff systems consisted in wave energy converters are studied in this paper. Wave energy converters are systems that are designed to produce electricity by capturing the power of ocean surface waves. Research activities on producing electricity from environmentally friendly and sustainable sources have been in progress since the days of Energy Crisis. Ocean waves are one of such energy sources. Many different types of wave energy converters were designed so far. The power of waves is converted into electricity by the power takeoff system of the wave energy converter. High pressure oil hydraulic systems, air turbines, hydraulic turbines and linear generators are frequently used types of power takeoff mechanisms. Each type of system has its advantages and disadvantages. The decision on which type of power takeoff system to be used in a wave energy converter mainly depends on the method of capturing the power of waves. DALGA ENERJİSİ JENERATÖRLERİNDE KULLANILAN GÜÇ DÖNÜŞÜM SİSTEMLERİNİN İNCELENMESİ Özetçe Bu çalışmada dalga enerjisi dönüştürücülerinde yaygın olarak kullanılan güç dönüşüm sistemleri incelenmiştir. Dalga enerjisi dönüştürücüleri okyanusların serbest sathında oluşan dalgaların gücünü elektrik enerjisine dönüştüren sistemlerdir. Çevre dostu ve sürdürülebilir kaynaklardan elektrik enerjisi üretmek üzere yapılan araştırmalar Enerji Krizi'nin yaşandığı günlerden beri devam etmektedir. Okyanus dalgaları bu tür enerji kaynaklarından bir tanesidir. Bugüne kadar birbirinden farklı, çok sayıda dalga enerjisi dönüştürücüsü dizayn edilmiştir. Dalgaların gücü, dalga enerjisi dönüştürücüsü içinde A Review Of Power TakeOff Systems Employed in Wave Energy Converters 33 bulunan bir güç dönüşüm sistemi vasıtasıyla elektrik enerjisine dönüştürülür. Yüksek basınçlı yağ ile çalışan hidrolik sistemler, hava türbinleri, su türbinleri ve doğrusal jeneratörler dalga enerjisi dönüştürücülerinde sıklıkla güç dönüşüm sistemi olarak kullanılmaktadır. Her sistemin avantajları ve dezavantajları bulunmaktadır. Bir dalga enerjisi dönüştürücüsünde hangi tip güç dönüştürücüsünün kullanılacağı temelde dalgaların gücünün toplanma şekline bağlıdır.

Ocean Engineering, Dec 1, 2020

A parametric optimization study is carried out to find an optimal design to capture the maximum e... more A parametric optimization study is carried out to find an optimal design to capture the maximum energy in a target area off the Turkish coast of the Black Sea. A heaving point absorber wave energy converter is analyzed by taking into account different float geometries with various dimensions and several hydraulic Power TakeOff parameters. The calculations are carried out in time domain by modeling each sea state observed in the target area. The effects of the geometry, mass, and the dimensions of the floats and the parameters of the Power TakeOff system on the energy generated from the waves are investigated and discussed. The analyses showed that the maximum pressure of the hydraulic accumulator, the cross-sectional area of the hydraulic piston, and the flow rate of the hydraulic fluid can be selected to combine the values of those which the WEC performs best in the sea state that possesses nearly similar energy as the annual average of all sea states observed in the target area. The cost of energy is also evaluated and it is found that the most economical WEC differs by float geometry.

DergiPark (Istanbul University), Feb 7, 2017

Bu çalışmada motorbotların tarihi gelişimine değinilerek motorbotlar için günümüzde kullanılan di... more Bu çalışmada motorbotların tarihi gelişimine değinilerek motorbotlar için günümüzde kullanılan direnç tahmin yöntemleri kısaca açıklanmıştır. Savitsky, Radojcic, Blount-Fox, Lahtiharju ve Wyman yöntemleri ele alınıp incelenmiş ve bu yöntemlerden bazıları örnek bir kayıcı tekneye uygulanıp direnç tahminleri yapılarak sonuçlar karşılaştırılmıştır. Çalışmada, kayıcı teknelerin ön tasarımında gerekli olan güç değerlerinin belirlenmesi konusunda, hangi yöntemin, hangi aralıklarda daha tutarlı çalıştığının bulunması amaçlanmıştır.

The power generated by eight point absorber type wave energy converters each having a different b... more The power generated by eight point absorber type wave energy converters each having a different buoy are calculated in order to investigate the performances of buoys in this study. The calculations are carried out by modeling three different sea states observed in two different locations in the Black Sea. The floats analyzed in this study have two basic geometries and four different draft/radius (d/r) ratios. The buoys possess the shapes of a semi-ellipsoid and a semi-elliptic paraboloid. Additionally, the draft/radius ratios range from 0.25 to 1 by an increment of 0.25. The radiation forces acting on the buoys due to the oscillatory motions of these bodies are evaluated by employing a 3D panel method along with a distribution of 3D pulsating sources in frequency domain. On the other hand, the wave forces acting on the buoys which are taken as the sum of Froude-Krylov forces and diffraction forces are calculated by using linear wave theory. Furthermore, the wave energy converters ar...

In this study, the surface of a Marine Vehicle has been determined by using the B-surface spline ... more In this study, the surface of a Marine Vehicle has been determined by using the B-surface spline which passes through the values of a given vehicle's offset table. The mathematical model of a ship is based on the cubic B-surface spline. The loaded waterline is represented by the plane z = 0. The volume under the loaded waterline is the intersection of this plane and the ship body. Thus rotating and translating the ship hull one can obtain any draught, roll and pitch position. The volume is computed with finite tetrahedra, having one of their nodes at the origin, the reminding three at the wetted surface of the ship. Using that representation of the volume element, it is possible to compute the wetted surface area, the centre of buoyancy and the normal unit vector to the surface at any position. These are of great importance in resistance and stability calculation. The computer program which has been developed is designed to calculate the stability terms of a ship. The program al...

… (2008) International Offshore and Offshore and …, 2008

In this paper, two multi point mooring systems which are under the action of periodic wave excita... more In this paper, two multi point mooring systems which are under the action of periodic wave excitation are considered in order to find out the approximate responses by using Runge Kutta Method. One of the mooring systems is anchored to the seabed with four mooring lines ...

2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021

Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in ai... more Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in air pollution is also striking drive to switch fuel-sourced metrobusses into electric ones. Therefore, according to Istanbul's promising potential with long Bus Rapid Transit Systems (BRT) and existing problem with high levels of air pollutants, integration of Electric Bus Rapid Transit System (e-BRT) offers a core solution. This study is the preliminary feasibility analysis of e-BRT for the longest round-route of Sogutlucesme-Beylikduzu (SB-BS), Istanbul, Turkey. For e-BRT adaptation, two actively on service metrobus models of Mercedes Benz™ are selected as 18-m-long Conecto G with 150 passenger and 21-m-long CapaCity L with 191-passenger. Real-time 3-axis acceleration, 3-axis magnetometer, latitude, longitude and barometric height measurements on the selected round-route of SB-BS under dynamic passenger load are collected and analyzed. 3D-accelerometer measurements are filtered with 8th order low-pass and high-pass Butterworth filters with respective cut-off frequencies of 4.5 Hz and 100 Hz prior to each integration, FFT, Periodogram, PSD, Welch-PSD and RMS analysis on MATLAB. The major purpose of acceleration measurements is to form a reference energy state of current fuel-sourced BRT so that future e-BRT system can be compared and feasibility of e-BRT can be conducted. Meanwhile, magnetometer measurements are performed to form a comparison with future e-BRT system. This will allow to detect higher existing magnetic field in e-metrobus so that necessary precautions can be taken for passenger safety. Finally, latitude, longitude and barometric height measurements are collected in order to map 3D route, inclines and maneuvering locations and to provide additional information on results of acceleration analyses. Moreover, to detect the most challenging route that e-BRT need to cover, maximum energy consuming route is extracted upon collected and analyzed current BRT measurements. All comparisons are performed upon requested original fuel-sourced BRT on active service durations and on the exact date of the measurements. Results indicate that the energy dissipation is maximum on CapaCity L at rear seat without suspension on Beylikduzu-Sogutlucesme (BS) route direction. Statistically, required energy need to cover SB route is greater than BS due to steep inclines. It is found that 37.5% of displacement power is stored in suspension systems. Reported peak magnetic field of electric vehicles is greater than BRT of Istanbul by only 98 µT.

Journal of ETA Maritime Science, 2017

Denizaltılar bir donanma için olmazsa olmaz unsurlar olup, savaş durumlarında savaşın kaderini ta... more Denizaltılar bir donanma için olmazsa olmaz unsurlar olup, savaş durumlarında savaşın kaderini tayin eden kritik sualtı araçlarıdır. Geçen yüzyılda tezahür eden iki dünya savaşının tarihi incelendiğinde, tarafların sahip oldukları deniz teknolojileri arasındaki küçük farklar savaşın kaderini tayin etmiştir. Bu denli küçük teknolojik farklar dahi savaşlarda büyük getiriler sağlayabildiğinden, gemilerin öndizayn aşamasında yapılan çalışmalar oldukça önem kazanmaktadır. Denizaltı dizaynı teknolojik ve hidrodinamik açıdan iyi bir şekilde yapıldığında, düşük direnç ve yüksek hız değerlerine ulaşılabilmekte ve bu durum da denizaltıları çok daha etkili konumlara getirebilmektedir. Denizaltı formlarının gelişimi tipik bir hal almış, paralel orta gövdenin başında ve kıçında yumuşak geçişlere sahip kıvrımlardan oluşmaktadır. Bu çalışmada takıntısız denizaltı gövdesi etrafındaki hidrodinamik özelliklerin incelenmesi adına, farklı genişlik-derinlik (B/D), genişlik-boy (B/L) ve ön gövde boyu-toplam boy (L f /L) oranlarına sahip üç farklı takıntısız denizaltı gövde grubu oluşturulmuştur. Oluşturulan bu denizaltı gövde gruplarının hidrodinamik analizlerinin yapılması için RANS tabanlı ticari bir hesaplamalı akışkanlar dinamiği kodu kullanılmıştır. Ticari kod ilk önce, literatürde deney sonuçları bulunan bir geometri üzerinde denenmiştir. Uygulanan HAD tekniğinin deney sonuçlarıyla uyumu gözlemlendikten sonra, çalışma kapsamında incelenmek istenen denizaltı grupları benzer sayısal yapı kullanılarak analiz edilmiş ve farklı formların toplam direnç üzerindeki etkileri incelenmiştir.

A direct and an iterative boundary element method using source distributions to represent the bod... more A direct and an iterative boundary element method using source distributions to represent the body are applied to calculate the pressure distribution on symmetric NACA airfoils. First, the effects of the foils on each other are examined. Then, the two methods are compared in terms of the solutions they generate and the time consumed. The calculations are made for different distances, panels and airfoil thicknesses to fully understand the basics of the interaction and the applicability of the iterative method.

CENTRAL EUROPEAN SYMPOSIUM ON THERMOPHYSICS 2021 (CEST 2021), 2021

In this paper the flow field around a submarine has been investigated. Pressure distribution and ... more In this paper the flow field around a submarine has been investigated. Pressure distribution and its impact on submarine hull form have been studied. The accurate and efficient prediction of hydrodynamic pressure and forces on a submarine has been achieved by investigating the flow related to the interaction of the vertical flow shed from the sail and the cross-flow boundary layer of the hull. Therefore this study aims to simulate the flow field of a submarine by using finite volume method. Finite Volume Stress Analysis Method and k-ω turbulence model have been used to simulate turbulent flow past the submarine hull surface. A submarine hull with overall length of 80 meters and diameter of 10 meters was chosen. It has aft body length 11m and sail length 7m. The speed range of the submarine is 0 to 30 knots with 5 knots increments. Calculated pressure coefficients along the submarine hull are discussed to show the effect of the sail lateral position and the stern appendages. It is ...

Turkish Journal of Engineering, 2018

Scientific Bulletin of Naval Academy, 2016

Tandem hydrofoil system is used even in the most ordinary ships; the hydrofoil that confronts the... more Tandem hydrofoil system is used even in the most ordinary ships; the hydrofoil that confronts the flow first represents the ship section, while the other hydrofoil stands for the rudder section. This study covers a parametric study on tandem hydrofoil interaction including variations of distance, thickness, angle of attack and chord length of hydrofoils. Circulation values of each hydrofoil are investigated to examine the strength of the interaction. 2-D iterative boundary element method is used with potential theory and the graphs of distance, thickness, angle of attack and chord length versus circulation are obtained. The implied aim is to maintain the optimum parameters for maximum lift and ship maneuverability.

2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021

Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in ai... more Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in air pollution is also striking drive to switch fuel-sourced metrobusses into electric ones. Therefore, according to Istanbul's promising potential with long Bus Rapid Transit Systems (BRT) and existing problem with high levels of air pollutants, integration of Electric Bus Rapid Transit System (e-BRT) offers a core solution. This study is the preliminary feasibility analysis of e-BRT for the longest round-route of Sogutlucesme-Beylikduzu (SB-BS), Istanbul, Turkey. For e-BRT adaptation, two actively on service metrobus models of Mercedes Benz™ are selected as 18-m-long Conecto G with 150 passenger and 21-m-long CapaCity L with 191-passenger. Real-time 3-axis acceleration, 3-axis magnetometer, latitude, longitude and barometric height measurements on the selected round-route of SB-BS under dynamic passenger load are collected and analyzed. 3D-accelerometer measurements are filtered with 8th order low-pass and high-pass Butterworth filters with respective cut-off frequencies of 4.5 Hz and 100 Hz prior to each integration, FFT, Periodogram, PSD, Welch-PSD and RMS analysis on MATLAB. The major purpose of acceleration measurements is to form a reference energy state of current fuel-sourced BRT so that future e-BRT system can be compared and feasibility of e-BRT can be conducted. Meanwhile, magnetometer measurements are performed to form a comparison with future e-BRT system. This will allow to detect higher existing magnetic field in e-metrobus so that necessary precautions can be taken for passenger safety. Finally, latitude, longitude and barometric height measurements are collected in order to map 3D route, inclines and maneuvering locations and to provide additional information on results of acceleration analyses. Moreover, to detect the most challenging route that e-BRT need to cover, maximum energy consuming route is extracted upon collected and analyzed current BRT measurements. All comparisons are performed upon requested original fuel-sourced BRT on active service durations and on the exact date of the measurements. Results indicate that the energy dissipation is maximum on CapaCity L at rear seat without suspension on Beylikduzu-Sogutlucesme (BS) route direction. Statistically, required energy need to cover SB route is greater than BS due to steep inclines. It is found that 37.5% of displacement power is stored in suspension systems. Reported peak magnetic field of electric vehicles is greater than BRT of Istanbul by only 98 µT.

Gemi ve deniz teknolojisi, Feb 7, 2017

The reliable Renewable Energy Systems development is being a primary topic in several research ar... more The reliable Renewable Energy Systems development is being a primary topic in several research areas. This reliability can be achieved chiefly based on the right choice of the used development technology. At the present time, the power is obtained from conventional and renewable energy. Conventional power is produced from fosil fuels. The power obtained from renewable energy is the renewable power considered includes photovoltaic(PV), wind, and concentrated solar power (CSP). Moreover, renewable power usually uses local natural resources and encourages local manufacturing capabilities since fossil fuels are being depleted and nuclear power is not really safe. The power generation from renewable energy is getting more and more attention at the global level. In this study, alternative energy systems and applications to the yachts had been investigated. A detailed description of the system had been explained how to obtain the daily energy to be needed and usage in yacht by harnessing renewable energy from the wind and the Sun.

... Supplemental Notes: ABDI KUKNER OTHER PHYS. DESCRIPTION: XI CHARTS THESIS PH. ... University ... more ... Supplemental Notes: ABDI KUKNER OTHER PHYS. DESCRIPTION: XI CHARTS THESIS PH. ... University Microfilms International. 300 North Zeeb Road Ann Arbor, MI 48106 USA. Available from UC Berkeley Transportation Library through interlibrary loan or document delivery. ...

Ocean Engineering, Feb 1, 2017

Three wave energy converter arrays are analyzed to investigate the effects of the wave-body inter... more Three wave energy converter arrays are analyzed to investigate the effects of the wave-body interactions on the energy generation within arrays. The arrays are analyzed by modeling four sea states observed at each of two locations in the Turkish coasts of the Black Sea. A potential flow based solver which was formerly developed for the analysis of the ship motions has been modified to analyze the interaction of multiple bodies in time domain. A high pressure hydraulic power takeoff system is employed for converting the mechanical force and motion provided by the float of the wave energy converter. The results show that the energy generated by each wave energy converter in all arrays is less than that generated by a single isolated wave energy converter in both locations with all sea states. The amount of reduction in the energy generated diminishes with the sea states become more severe. While the amounts of energy generated by the wave energy converters in Array 1 and 2 are close to each other, the hydrodynamic interaction of multiple wave energy converters become more severe in Array 3 and the amount of the energy generated by each wave energy converter differ from one another significantly.

Journal of Naval Sciences and Engineering, Apr 1, 2014

The power takeoff systems consisted in wave energy converters are studied in this paper. Wave ene... more The power takeoff systems consisted in wave energy converters are studied in this paper. Wave energy converters are systems that are designed to produce electricity by capturing the power of ocean surface waves. Research activities on producing electricity from environmentally friendly and sustainable sources have been in progress since the days of Energy Crisis. Ocean waves are one of such energy sources. Many different types of wave energy converters were designed so far. The power of waves is converted into electricity by the power takeoff system of the wave energy converter. High pressure oil hydraulic systems, air turbines, hydraulic turbines and linear generators are frequently used types of power takeoff mechanisms. Each type of system has its advantages and disadvantages. The decision on which type of power takeoff system to be used in a wave energy converter mainly depends on the method of capturing the power of waves. DALGA ENERJİSİ JENERATÖRLERİNDE KULLANILAN GÜÇ DÖNÜŞÜM SİSTEMLERİNİN İNCELENMESİ Özetçe Bu çalışmada dalga enerjisi dönüştürücülerinde yaygın olarak kullanılan güç dönüşüm sistemleri incelenmiştir. Dalga enerjisi dönüştürücüleri okyanusların serbest sathında oluşan dalgaların gücünü elektrik enerjisine dönüştüren sistemlerdir. Çevre dostu ve sürdürülebilir kaynaklardan elektrik enerjisi üretmek üzere yapılan araştırmalar Enerji Krizi'nin yaşandığı günlerden beri devam etmektedir. Okyanus dalgaları bu tür enerji kaynaklarından bir tanesidir. Bugüne kadar birbirinden farklı, çok sayıda dalga enerjisi dönüştürücüsü dizayn edilmiştir. Dalgaların gücü, dalga enerjisi dönüştürücüsü içinde A Review Of Power TakeOff Systems Employed in Wave Energy Converters 33 bulunan bir güç dönüşüm sistemi vasıtasıyla elektrik enerjisine dönüştürülür. Yüksek basınçlı yağ ile çalışan hidrolik sistemler, hava türbinleri, su türbinleri ve doğrusal jeneratörler dalga enerjisi dönüştürücülerinde sıklıkla güç dönüşüm sistemi olarak kullanılmaktadır. Her sistemin avantajları ve dezavantajları bulunmaktadır. Bir dalga enerjisi dönüştürücüsünde hangi tip güç dönüştürücüsünün kullanılacağı temelde dalgaların gücünün toplanma şekline bağlıdır.

Ocean Engineering, Dec 1, 2020

A parametric optimization study is carried out to find an optimal design to capture the maximum e... more A parametric optimization study is carried out to find an optimal design to capture the maximum energy in a target area off the Turkish coast of the Black Sea. A heaving point absorber wave energy converter is analyzed by taking into account different float geometries with various dimensions and several hydraulic Power TakeOff parameters. The calculations are carried out in time domain by modeling each sea state observed in the target area. The effects of the geometry, mass, and the dimensions of the floats and the parameters of the Power TakeOff system on the energy generated from the waves are investigated and discussed. The analyses showed that the maximum pressure of the hydraulic accumulator, the cross-sectional area of the hydraulic piston, and the flow rate of the hydraulic fluid can be selected to combine the values of those which the WEC performs best in the sea state that possesses nearly similar energy as the annual average of all sea states observed in the target area. The cost of energy is also evaluated and it is found that the most economical WEC differs by float geometry.

DergiPark (Istanbul University), Feb 7, 2017

Bu çalışmada motorbotların tarihi gelişimine değinilerek motorbotlar için günümüzde kullanılan di... more Bu çalışmada motorbotların tarihi gelişimine değinilerek motorbotlar için günümüzde kullanılan direnç tahmin yöntemleri kısaca açıklanmıştır. Savitsky, Radojcic, Blount-Fox, Lahtiharju ve Wyman yöntemleri ele alınıp incelenmiş ve bu yöntemlerden bazıları örnek bir kayıcı tekneye uygulanıp direnç tahminleri yapılarak sonuçlar karşılaştırılmıştır. Çalışmada, kayıcı teknelerin ön tasarımında gerekli olan güç değerlerinin belirlenmesi konusunda, hangi yöntemin, hangi aralıklarda daha tutarlı çalıştığının bulunması amaçlanmıştır.

The power generated by eight point absorber type wave energy converters each having a different b... more The power generated by eight point absorber type wave energy converters each having a different buoy are calculated in order to investigate the performances of buoys in this study. The calculations are carried out by modeling three different sea states observed in two different locations in the Black Sea. The floats analyzed in this study have two basic geometries and four different draft/radius (d/r) ratios. The buoys possess the shapes of a semi-ellipsoid and a semi-elliptic paraboloid. Additionally, the draft/radius ratios range from 0.25 to 1 by an increment of 0.25. The radiation forces acting on the buoys due to the oscillatory motions of these bodies are evaluated by employing a 3D panel method along with a distribution of 3D pulsating sources in frequency domain. On the other hand, the wave forces acting on the buoys which are taken as the sum of Froude-Krylov forces and diffraction forces are calculated by using linear wave theory. Furthermore, the wave energy converters ar...

In this study, the surface of a Marine Vehicle has been determined by using the B-surface spline ... more In this study, the surface of a Marine Vehicle has been determined by using the B-surface spline which passes through the values of a given vehicle's offset table. The mathematical model of a ship is based on the cubic B-surface spline. The loaded waterline is represented by the plane z = 0. The volume under the loaded waterline is the intersection of this plane and the ship body. Thus rotating and translating the ship hull one can obtain any draught, roll and pitch position. The volume is computed with finite tetrahedra, having one of their nodes at the origin, the reminding three at the wetted surface of the ship. Using that representation of the volume element, it is possible to compute the wetted surface area, the centre of buoyancy and the normal unit vector to the surface at any position. These are of great importance in resistance and stability calculation. The computer program which has been developed is designed to calculate the stability terms of a ship. The program al...

… (2008) International Offshore and Offshore and …, 2008

In this paper, two multi point mooring systems which are under the action of periodic wave excita... more In this paper, two multi point mooring systems which are under the action of periodic wave excitation are considered in order to find out the approximate responses by using Runge Kutta Method. One of the mooring systems is anchored to the seabed with four mooring lines ...

2021 International Conference on Electrical, Computer and Energy Technologies (ICECET), 2021

Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in ai... more Since 2017, initiation of electric metrobuses is projected, especially in USA. Resulted aid in air pollution is also striking drive to switch fuel-sourced metrobusses into electric ones. Therefore, according to Istanbul's promising potential with long Bus Rapid Transit Systems (BRT) and existing problem with high levels of air pollutants, integration of Electric Bus Rapid Transit System (e-BRT) offers a core solution. This study is the preliminary feasibility analysis of e-BRT for the longest round-route of Sogutlucesme-Beylikduzu (SB-BS), Istanbul, Turkey. For e-BRT adaptation, two actively on service metrobus models of Mercedes Benz™ are selected as 18-m-long Conecto G with 150 passenger and 21-m-long CapaCity L with 191-passenger. Real-time 3-axis acceleration, 3-axis magnetometer, latitude, longitude and barometric height measurements on the selected round-route of SB-BS under dynamic passenger load are collected and analyzed. 3D-accelerometer measurements are filtered with 8th order low-pass and high-pass Butterworth filters with respective cut-off frequencies of 4.5 Hz and 100 Hz prior to each integration, FFT, Periodogram, PSD, Welch-PSD and RMS analysis on MATLAB. The major purpose of acceleration measurements is to form a reference energy state of current fuel-sourced BRT so that future e-BRT system can be compared and feasibility of e-BRT can be conducted. Meanwhile, magnetometer measurements are performed to form a comparison with future e-BRT system. This will allow to detect higher existing magnetic field in e-metrobus so that necessary precautions can be taken for passenger safety. Finally, latitude, longitude and barometric height measurements are collected in order to map 3D route, inclines and maneuvering locations and to provide additional information on results of acceleration analyses. Moreover, to detect the most challenging route that e-BRT need to cover, maximum energy consuming route is extracted upon collected and analyzed current BRT measurements. All comparisons are performed upon requested original fuel-sourced BRT on active service durations and on the exact date of the measurements. Results indicate that the energy dissipation is maximum on CapaCity L at rear seat without suspension on Beylikduzu-Sogutlucesme (BS) route direction. Statistically, required energy need to cover SB route is greater than BS due to steep inclines. It is found that 37.5% of displacement power is stored in suspension systems. Reported peak magnetic field of electric vehicles is greater than BRT of Istanbul by only 98 µT.

Journal of ETA Maritime Science, 2017

Denizaltılar bir donanma için olmazsa olmaz unsurlar olup, savaş durumlarında savaşın kaderini ta... more Denizaltılar bir donanma için olmazsa olmaz unsurlar olup, savaş durumlarında savaşın kaderini tayin eden kritik sualtı araçlarıdır. Geçen yüzyılda tezahür eden iki dünya savaşının tarihi incelendiğinde, tarafların sahip oldukları deniz teknolojileri arasındaki küçük farklar savaşın kaderini tayin etmiştir. Bu denli küçük teknolojik farklar dahi savaşlarda büyük getiriler sağlayabildiğinden, gemilerin öndizayn aşamasında yapılan çalışmalar oldukça önem kazanmaktadır. Denizaltı dizaynı teknolojik ve hidrodinamik açıdan iyi bir şekilde yapıldığında, düşük direnç ve yüksek hız değerlerine ulaşılabilmekte ve bu durum da denizaltıları çok daha etkili konumlara getirebilmektedir. Denizaltı formlarının gelişimi tipik bir hal almış, paralel orta gövdenin başında ve kıçında yumuşak geçişlere sahip kıvrımlardan oluşmaktadır. Bu çalışmada takıntısız denizaltı gövdesi etrafındaki hidrodinamik özelliklerin incelenmesi adına, farklı genişlik-derinlik (B/D), genişlik-boy (B/L) ve ön gövde boyu-toplam boy (L f /L) oranlarına sahip üç farklı takıntısız denizaltı gövde grubu oluşturulmuştur. Oluşturulan bu denizaltı gövde gruplarının hidrodinamik analizlerinin yapılması için RANS tabanlı ticari bir hesaplamalı akışkanlar dinamiği kodu kullanılmıştır. Ticari kod ilk önce, literatürde deney sonuçları bulunan bir geometri üzerinde denenmiştir. Uygulanan HAD tekniğinin deney sonuçlarıyla uyumu gözlemlendikten sonra, çalışma kapsamında incelenmek istenen denizaltı grupları benzer sayısal yapı kullanılarak analiz edilmiş ve farklı formların toplam direnç üzerindeki etkileri incelenmiştir.

A direct and an iterative boundary element method using source distributions to represent the bod... more A direct and an iterative boundary element method using source distributions to represent the body are applied to calculate the pressure distribution on symmetric NACA airfoils. First, the effects of the foils on each other are examined. Then, the two methods are compared in terms of the solutions they generate and the time consumed. The calculations are made for different distances, panels and airfoil thicknesses to fully understand the basics of the interaction and the applicability of the iterative method.

CENTRAL EUROPEAN SYMPOSIUM ON THERMOPHYSICS 2021 (CEST 2021), 2021

In this paper the flow field around a submarine has been investigated. Pressure distribution and ... more In this paper the flow field around a submarine has been investigated. Pressure distribution and its impact on submarine hull form have been studied. The accurate and efficient prediction of hydrodynamic pressure and forces on a submarine has been achieved by investigating the flow related to the interaction of the vertical flow shed from the sail and the cross-flow boundary layer of the hull. Therefore this study aims to simulate the flow field of a submarine by using finite volume method. Finite Volume Stress Analysis Method and k-ω turbulence model have been used to simulate turbulent flow past the submarine hull surface. A submarine hull with overall length of 80 meters and diameter of 10 meters was chosen. It has aft body length 11m and sail length 7m. The speed range of the submarine is 0 to 30 knots with 5 knots increments. Calculated pressure coefficients along the submarine hull are discussed to show the effect of the sail lateral position and the stern appendages. It is ...

Turkish Journal of Engineering, 2018

Scientific Bulletin of Naval Academy, 2016

Tandem hydrofoil system is used even in the most ordinary ships; the hydrofoil that confronts the... more Tandem hydrofoil system is used even in the most ordinary ships; the hydrofoil that confronts the flow first represents the ship section, while the other hydrofoil stands for the rudder section. This study covers a parametric study on tandem hydrofoil interaction including variations of distance, thickness, angle of attack and chord length of hydrofoils. Circulation values of each hydrofoil are investigated to examine the strength of the interaction. 2-D iterative boundary element method is used with potential theory and the graphs of distance, thickness, angle of attack and chord length versus circulation are obtained. The implied aim is to maintain the optimum parameters for maximum lift and ship maneuverability.