Bu çalışmada, γ türbülans geçiş modelinin (çapraz akış etkisinin dahil edildiği ve edilmediği versiyonları kullanılarak) 6:1 küremsi geometri üzerinde düzensiz çözüm ağı kullanılarak 6.5 x 10-6 Reynolds sayısında ve 5o hücum açısında başarım değerlendirmesi amaçlanmaktadır. γ türbülans geçiş modelinin performans değerlendirmesi, SST k-ω türbülans modeli, en popüler türbülans geçiş modeli olan γ-〖Re〗_θ türbülans geçiş modeli ve halihazırda mevcut deneysel veri sonuçları kullanılarak yapılmıştır. Türbülans geçiş modelinin etkisi eksenel kuvvet katsayısı, normal kuvvet katsayısı, yüzey basınç katsayısı ve yüzey sürtünme katsayısı kullanılarak gösterilmiştir. Eksenel kuvvet ve normal kuvvet katsayıları etrafındaki ayrıklaştırma hata bandı “Grid Convergence Index” (GCI) metodu kullanılarak elde edilmiştir. Türbülans geçiş modelleri kuvvet katsayılarını, akışın tamamıyla türbülanslı olması kabulüyle yapılan analizlere göre daha büyük GCI değerleriyle %58 daha az tahmin etmiştir. Türbülans geçiş modelleri yüzey basınç katsayılarında fazla değişiklik yaratmazken, yüzey sürtünme katsaylarında önemli farklılıklar görülmüştür. Türbülans geçiş modelleri küremsi geometrinin üst yüzeyinde yüzey sürtünme katsayıları açısından önemli farklılıklar yakalasa da bu kuvvetli değişiklikler tamamıyla türbülanslı akış analizlerinde gözlemlenmemektedir. Diğer yandan, deneysel sonuçların tersine, analizlerde küremsi geometrinin alt yüzeyinde türbülans geçişine dair hiçbir işaret görülmemektedir. Sonuç olarak, geçiş modelleri türbülans geçiş bölgesi geometrisini doğru tahmin edememektedirler. Bunun yanı sıra, γ türbülans geçiş modelinin, γ-〖Re〗_θ türbülans geçiş modeline göre yüzey çözüm ağı büyüklüğüne daha hassas olduğu tespit edilmiştir. γ türbülans geçiş modelinin bir diğer dezavantajı da çözümleme zamanıdır. γ türbülans geçiş modeli, γ-〖Re〗_θ geçiş modeline göre daha basit olmasına rağmen, kuvvet katsayılarında daha yavaş iterasyon yakınsama oranına sebebiyle hesaplaması yaklaşık 3.8 kat daha fazla zaman almıştır. Çapraz akış etkisinin γ türbülans geçiş modeline dahil edilmesi, geçiş bölge geometrisi ve çözümleme zamanı açısından sonuçları fazla değiştirmemiştir. Bu çalışmada sunulan sonuçlar, geçiş bölgesini doğru tahmin etmek amacıyla gelecekte yapılacak çalışmalarda ve geçiş modellerinin hata tahminlerinin yapılmasında kullanılabilecektir.
{"title":"γ Türbülans Geçiş Modelinin Kuvvet Katsayıları ve Geçiş Yer Tahmini için Başarım Değerlendirmesi","authors":"Hediye Ati̇k","doi":"10.54926/gdt.1131963","DOIUrl":"https://doi.org/10.54926/gdt.1131963","url":null,"abstract":"Bu çalışmada, γ türbülans geçiş modelinin (çapraz akış etkisinin dahil edildiği ve edilmediği versiyonları kullanılarak) 6:1 küremsi geometri üzerinde düzensiz çözüm ağı kullanılarak 6.5 x 10-6 Reynolds sayısında ve 5o hücum açısında başarım değerlendirmesi amaçlanmaktadır. γ türbülans geçiş modelinin performans değerlendirmesi, SST k-ω türbülans modeli, en popüler türbülans geçiş modeli olan γ-〖Re〗_θ türbülans geçiş modeli ve halihazırda mevcut deneysel veri sonuçları kullanılarak yapılmıştır. Türbülans geçiş modelinin etkisi eksenel kuvvet katsayısı, normal kuvvet katsayısı, yüzey basınç katsayısı ve yüzey sürtünme katsayısı kullanılarak gösterilmiştir. Eksenel kuvvet ve normal kuvvet katsayıları etrafındaki ayrıklaştırma hata bandı “Grid Convergence Index” (GCI) metodu kullanılarak elde edilmiştir. Türbülans geçiş modelleri kuvvet katsayılarını, akışın tamamıyla türbülanslı olması kabulüyle yapılan analizlere göre daha büyük GCI değerleriyle %58 daha az tahmin etmiştir. Türbülans geçiş modelleri yüzey basınç katsayılarında fazla değişiklik yaratmazken, yüzey sürtünme katsaylarında önemli farklılıklar görülmüştür. Türbülans geçiş modelleri küremsi geometrinin üst yüzeyinde yüzey sürtünme katsayıları açısından önemli farklılıklar yakalasa da bu kuvvetli değişiklikler tamamıyla türbülanslı akış analizlerinde gözlemlenmemektedir. Diğer yandan, deneysel sonuçların tersine, analizlerde küremsi geometrinin alt yüzeyinde türbülans geçişine dair hiçbir işaret görülmemektedir. Sonuç olarak, geçiş modelleri türbülans geçiş bölgesi geometrisini doğru tahmin edememektedirler. Bunun yanı sıra, γ türbülans geçiş modelinin, γ-〖Re〗_θ türbülans geçiş modeline göre yüzey çözüm ağı büyüklüğüne daha hassas olduğu tespit edilmiştir. γ türbülans geçiş modelinin bir diğer dezavantajı da çözümleme zamanıdır. γ türbülans geçiş modeli, γ-〖Re〗_θ geçiş modeline göre daha basit olmasına rağmen, kuvvet katsayılarında daha yavaş iterasyon yakınsama oranına sebebiyle hesaplaması yaklaşık 3.8 kat daha fazla zaman almıştır. Çapraz akış etkisinin γ türbülans geçiş modeline dahil edilmesi, geçiş bölge geometrisi ve çözümleme zamanı açısından sonuçları fazla değiştirmemiştir. Bu çalışmada sunulan sonuçlar, geçiş bölgesini doğru tahmin etmek amacıyla gelecekte yapılacak çalışmalarda ve geçiş modellerinin hata tahminlerinin yapılmasında kullanılabilecektir.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124657092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tonaj ve değer olarak küresel ticaretin taşınmasında en büyük paya sahip olan denizyolu taşımacılığından kaynaklanan emisyonların dünya toplamı içindeki payı günden güne artmaktadır. Uluslararası Denizcilik Örgütü, bu gidişatı engellemek adına gemilerden kaynaklı emisyonların azaltılmasına yönelik regülasyonlar yayınladı. Bu regülasyonlara göre gemilerden kaynaklı çeşitli zararlı gazlara ait emisyon oranları yıllar içerisinde daha da azaltılacaktır. IMO 2020 kuralları çerçevesinde gemilerden kaynaklı kükürt gazı emisyonlarının azaltılmasına odaklanılmışken, 2050 yılı itibariyle karbon salınımlarının sıfırlanması beklenmektedir. Bu çerçevede denizcilik işletmeleri arasında hali hazırda üst seviyede seyreden rekabet sahası genişleyecektir. Bu kapsamda işletmelerin kendi kaynaklarını geliştirerek rekabetçi avantaj yakalayabileceğini savunan kaynak temelli bakış açısı yakıt teknolojisinin gelişimine uyum açısından denizcilik işletmelerine rehber olabilecektir. Bu çalışmada IMO 2050 kuralları kapsamında karbonu sıfırlayan alternatif gemi yakıtları çeşitli yönlerden değerlendirilmiştir. Alternatif yakıtlar içerisinden doğalgaz, metanol, amonyak ve hidrojen ele alınmış, teknik, ekonomik, lojistik vb. özellikleri detaylandırılmıştır. Değerlendirme kapsamında alternatiflerin teknik, ekonomik, lojistik vs. açılardan güçlü ve zayıf yönleri ortaya konulmuştur. Bu bağlamda alternatif gemi yakıtları rekabetçi avantaj kapsamında ele alınarak teoriye katkı sağlanmıştır. Alternatif yakıtların kullanımı, tedariği, depolanması gibi konularda bilgi verilmesi ile uygulayıcılara bir bilişsel çerçeve sunulmuştur.
{"title":"Deniz Taşımacılığında Dekarbonizasyon Uygulamalarının Kaynak Temelli Görüş Bağlamında Alternatif Yakıtlar Açısından Değerlendirilmesi","authors":"Murat Bayraktar, Umur Bucak, Hakan Demi̇rel","doi":"10.54926/gdt.1093206","DOIUrl":"https://doi.org/10.54926/gdt.1093206","url":null,"abstract":"Tonaj ve değer olarak küresel ticaretin taşınmasında en büyük paya sahip olan denizyolu taşımacılığından kaynaklanan emisyonların dünya toplamı içindeki payı günden güne artmaktadır. Uluslararası Denizcilik Örgütü, bu gidişatı engellemek adına gemilerden kaynaklı emisyonların azaltılmasına yönelik regülasyonlar yayınladı. Bu regülasyonlara göre gemilerden kaynaklı çeşitli zararlı gazlara ait emisyon oranları yıllar içerisinde daha da azaltılacaktır. IMO 2020 kuralları çerçevesinde gemilerden kaynaklı kükürt gazı emisyonlarının azaltılmasına odaklanılmışken, 2050 yılı itibariyle karbon salınımlarının sıfırlanması beklenmektedir. Bu çerçevede denizcilik işletmeleri arasında hali hazırda üst seviyede seyreden rekabet sahası genişleyecektir. Bu kapsamda işletmelerin kendi kaynaklarını geliştirerek rekabetçi avantaj yakalayabileceğini savunan kaynak temelli bakış açısı yakıt teknolojisinin gelişimine uyum açısından denizcilik işletmelerine rehber olabilecektir. Bu çalışmada IMO 2050 kuralları kapsamında karbonu sıfırlayan alternatif gemi yakıtları çeşitli yönlerden değerlendirilmiştir. Alternatif yakıtlar içerisinden doğalgaz, metanol, amonyak ve hidrojen ele alınmış, teknik, ekonomik, lojistik vb. özellikleri detaylandırılmıştır. Değerlendirme kapsamında alternatiflerin teknik, ekonomik, lojistik vs. açılardan güçlü ve zayıf yönleri ortaya konulmuştur. Bu bağlamda alternatif gemi yakıtları rekabetçi avantaj kapsamında ele alınarak teoriye katkı sağlanmıştır. Alternatif yakıtların kullanımı, tedariği, depolanması gibi konularda bilgi verilmesi ile uygulayıcılara bir bilişsel çerçeve sunulmuştur.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129220854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bilindiği üzere, DARPA SUBOFF denizaltı modeli derin suda yatay stabiliteye sahip değildir. Bu çalışmada, denizaltı modelinin periskop (şnorkel) seyri esnasında veya su yüzeyine yakın hareket ederken yatay stabilitesi 3 serbestlik dereceli olarak tespit edilmiştir. Denizaltı stabilitesi ve hidrodinamik manevra türevleri tespit edilirken farklı derinliklerde yanal öteleme kuvvetine ait doğrusal katsayılar ve savrulma açısal momentine ait doğrusal katsayılar kullanılmıştır. Denizaltı çapı D olmak üzere, derinlikler 1.1D, 2.2D, 3.3D ve 6D olarak seçilmiştir. Manevra türevleri hesaplamalı akışkanlar dinamiği metodlarıyla bir seri sistematik analiz yapılarak elde edilmiştir. Hesaplamalı analizlerde gerekli doğrulama çalışmaları da yapılmıştır. Hesaplamalı akışkanlar dinamiği analizlerinde boyuna ve yanal kuvvet türevleri, ve savrulma momenti türevleri hesaplanarak doğrusal modelde X0, Xv, Xd, Xẟ, Yv, Yr, Yẟ. Nv, Nr ve Nẟ katsayıları belirlenmiş ve hidrodinamik model oluşturulmuştur. Farklı derinliklere göre elde edilen hidrodinamik türevler ile denizaltının yatay stabiliteye sahip olup olmadığı tespit edilmiştir. Denizaltı modelinin, serbest su yüzeyine yakın seyir durumlarında yatay stabiliyete sahip olduğu ve 4.6D derinlikten itibaren ise yatay stabilitesini kaybettiği bulunmuştur.
{"title":"Darpa Denizalti Modelinde Derinliğe Bağlı Olarak Değişen Hidrodinamik Manevra Türevlerinin ve Yatay Stabilitenin İncelenmesi","authors":"Furkan Çavdar, Şakir Bal","doi":"10.54926/gdt.1084413","DOIUrl":"https://doi.org/10.54926/gdt.1084413","url":null,"abstract":"Bilindiği üzere, DARPA SUBOFF denizaltı modeli derin suda yatay stabiliteye sahip değildir. Bu çalışmada, denizaltı modelinin periskop (şnorkel) seyri esnasında veya su yüzeyine yakın hareket ederken yatay stabilitesi 3 serbestlik dereceli olarak tespit edilmiştir. Denizaltı stabilitesi ve hidrodinamik manevra türevleri tespit edilirken farklı derinliklerde yanal öteleme kuvvetine ait doğrusal katsayılar ve savrulma açısal momentine ait doğrusal katsayılar kullanılmıştır. Denizaltı çapı D olmak üzere, derinlikler 1.1D, 2.2D, 3.3D ve 6D olarak seçilmiştir. Manevra türevleri hesaplamalı akışkanlar dinamiği metodlarıyla bir seri sistematik analiz yapılarak elde edilmiştir. Hesaplamalı analizlerde gerekli doğrulama çalışmaları da yapılmıştır. Hesaplamalı akışkanlar dinamiği analizlerinde boyuna ve yanal kuvvet türevleri, ve savrulma momenti türevleri hesaplanarak doğrusal modelde X0, Xv, Xd, Xẟ, Yv, Yr, Yẟ. Nv, Nr ve Nẟ katsayıları belirlenmiş ve hidrodinamik model oluşturulmuştur. Farklı derinliklere göre elde edilen hidrodinamik türevler ile denizaltının yatay stabiliteye sahip olup olmadığı tespit edilmiştir. Denizaltı modelinin, serbest su yüzeyine yakın seyir durumlarında yatay stabiliyete sahip olduğu ve 4.6D derinlikten itibaren ise yatay stabilitesini kaybettiği bulunmuştur.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"138 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133898017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The results of computational analyses on the manoeuvring performance of a stern trawler with an azimuth thruster located in the forward part of the vessel are presented. The initial design of the vessel with a single shaft, propeller and rudder is considered to have insufficient manoeuvring performance with a trawl pull load of 40 tons in moderate environmental conditions with a forward speed of 3 knots. The modified design is equipped with an azimuth thruster located in the forward part of the vessel that can rotate 360 degrees to produce additional thrust. In order to assess and simulate the manoeuvring performance of the vessel, the surge, sway and yaw equations are set and solved in the time domain. The hydrodynamic forces due to surge and sway motions and the yaw moment are represented by a nonlinear modular mathematical model. The manoeuvring coefficients of the mathematical model employed are estimated by two distinct approaches; the first one is based on semi-empirical methods and the other is based on computational fluid dynamics (CFD). The external forces due to wind, current and waves are mathematically represented by proven semi-empirical methods based on the results of scaled model tests and full-scale measurements. A comprehensive computational test matrix is established and extensive computational analyses and manoeuvring simulations were carried out to indicate that an azimuth thruster with sufficient thrust located in the forward part of a stern trawler could significantly improve the manoeuvring performance of the vessel despite adverse environmental conditions.
{"title":"The Effect of Azimuth Thruster on the Manoeuvring Ability of a Stern Trawler in Rough Weather Conditions","authors":"K. Sariöz, Ö. Gören, Ö. Kinaci, Aydin Sulus","doi":"10.54926/gdt.1108980","DOIUrl":"https://doi.org/10.54926/gdt.1108980","url":null,"abstract":"The results of computational analyses on the manoeuvring performance of a stern trawler with an azimuth thruster located in the forward part of the vessel are presented. The initial design of the vessel with a single shaft, propeller and rudder is considered to have insufficient manoeuvring performance with a trawl pull load of 40 tons in moderate environmental conditions with a forward speed of 3 knots. The modified design is equipped with an azimuth thruster located in the forward part of the vessel that can rotate 360 degrees to produce additional thrust. In order to assess and simulate the manoeuvring performance of the vessel, the surge, sway and yaw equations are set and solved in the time domain. The hydrodynamic forces due to surge and sway motions and the yaw moment are represented by a nonlinear modular mathematical model. The manoeuvring coefficients of the mathematical model employed are estimated by two distinct approaches; the first one is based on semi-empirical methods and the other is based on computational fluid dynamics (CFD). The external forces due to wind, current and waves are mathematically represented by proven semi-empirical methods based on the results of scaled model tests and full-scale measurements. A comprehensive computational test matrix is established and extensive computational analyses and manoeuvring simulations were carried out to indicate that an azimuth thruster with sufficient thrust located in the forward part of a stern trawler could significantly improve the manoeuvring performance of the vessel despite adverse environmental conditions.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114979803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a proposed mathematical model consists of two parts, one is the maneuvering model, called MMG (Mathematical Model Group), and the other is a control algorithm based on traditional PD control system. The MMG model is used to compute the ship's maneuvering characteristics, and a ship can safely reach target coordinates with the help of a control algorithm if it encounters any obstacles along the way. Because of the suitable hydrodynamic coefficients of Esso Osaka, the proposed mathematical model is evaluated using trial test data from Esso Osaka. Firstly, the maneuvering characteristics of the ship were determined by performing the turning and zigzag tests for different velocity of the ship. By comparing the results obtained with the trial test results of the Esso Osaka, the suggested model was verified. Secondly, the ship's route was obtained for a determined target coordinate. Thirdly, a new route is automatically obtained by assuming that there is an obstacle between the starting point of the ship and the target coordinate determined for the previous simulation. As a result, this new route is created thanks to the virtual coordinates determined in accordance with the COLREGs rules. Since the maneuvering characteristic values of the ship are included in the written algorithm, it directly affects the determination of the virtual coordinates. Therefore, it is very important to find accurate maneuvering characteristics. Evaluating the simulation results obtained from the proposed mathematical model, it is concluded that a safe route has been created between the coordinates determined for the Esso Osaka ship. Moreover, the ship reaches the target coordinate without any collision.
本文提出的数学模型由两部分组成，一部分是机动模型，称为MMG (mathematical model Group)，另一部分是基于传统PD控制系统的控制算法。利用MMG模型计算船舶的机动特性，使船舶在航行过程中遇到障碍物时，能够在控制算法的帮助下安全到达目标坐标。由于大阪埃索的水动力系数合适，采用大阪埃索的试验数据对所提出的数学模型进行了评价。首先，对舰船进行了不同航速下的转弯和之字形试验，确定了舰船的机动特性;通过与Esso大阪试验结果的比较，验证了所建模型的正确性。其次，在确定目标坐标的情况下，得到船舶航路;第三，假设船舶的起始点与前面仿真确定的目标坐标之间存在障碍物，自动获得新的路线。因此，这条新路线是根据COLREGs规则确定的虚拟坐标创建的。由于所编写的算法中包含了船舶的机动特性值，直接影响到虚拟坐标的确定。因此，找到准确的机动特性是非常重要的。通过对所建数学模型的仿真结果进行评估，得出了在确定的“大阪埃索”号船舶座标之间建立了一条安全航线的结论。并且舰船到达目标坐标时没有发生碰撞。
{"title":"Otonom su üstü araçları için COLREG kurallarını içeren çarpışma önleyici sistem","authors":"Gökhan Budak","doi":"10.54926/gdt.1104423","DOIUrl":"https://doi.org/10.54926/gdt.1104423","url":null,"abstract":"In this study, a proposed mathematical model consists of two parts, one is the maneuvering model, called MMG (Mathematical Model Group), and the other is a control algorithm based on traditional PD control system. The MMG model is used to compute the ship's maneuvering characteristics, and a ship can safely reach target coordinates with the help of a control algorithm if it encounters any obstacles along the way. Because of the suitable hydrodynamic coefficients of Esso Osaka, the proposed mathematical model is evaluated using trial test data from Esso Osaka. Firstly, the maneuvering characteristics of the ship were determined by performing the turning and zigzag tests for different velocity of the ship. By comparing the results obtained with the trial test results of the Esso Osaka, the suggested model was verified. Secondly, the ship's route was obtained for a determined target coordinate. Thirdly, a new route is automatically obtained by assuming that there is an obstacle between the starting point of the ship and the target coordinate determined for the previous simulation. As a result, this new route is created thanks to the virtual coordinates determined in accordance with the COLREGs rules. Since the maneuvering characteristic values of the ship are included in the written algorithm, it directly affects the determination of the virtual coordinates. Therefore, it is very important to find accurate maneuvering characteristics. Evaluating the simulation results obtained from the proposed mathematical model, it is concluded that a safe route has been created between the coordinates determined for the Esso Osaka ship. Moreover, the ship reaches the target coordinate without any collision.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123942683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The additive manufacturing method based on computer-aided design and three-dimensional printing technology, its speed, design freedom provided for the designers, the cost-effectiveness and competitive for relatively low-capacity production needs, the possibilities of achieving good quality; has been gained a popularity with the industries, including the maritime sector. The main proof of this interest is the significant increase in the number of research and development activities and scientific publications on this topic. Due to above mentioned advantages, it is inevitable for the small-marine craft industry, whose competitiveness can be made sustainable by frequently updating flexible designs, to adopt their technology to the additive manufacturing method. While it makes the design and manufacturing process of boats efficient, for getting more effective results; it requires past driven data approach on practical experience. In this study, the effect of infill density and pattern which are important parameters of the additive manufacturing method, on the tensile strength of the final product's basic mechanical properties was investigated experimentally. Tensile tests with 13 different printing pattern and 5 different infill density of polylactic acid (PLA), one of the polymers widely used based on three-dimensional printing technologies, and a test matrix consisting of five different filling densities as 10%, 25%, 50%, 75% and 100%, were performed in Dokuz Eylul University’s (DEU) Composite Laboratory. The results showed that the mechanical properties were very sensitive to these parameters, and the cubic pattern was generally effective in achieving the best mechanical properties at the investigated densities. Using this pattern and 25% density, sailboat hull with 1/5 scale was produced in DEU Institute of Marine Sciences and Technologies Additive Manufacturing Laboratory, using PLA polymer by additive manufacturing.
{"title":"The effects of infill density and pattern on the strength of marine small craft building by additive manufacturing method","authors":"Ayberk Sözen, G. Neşer","doi":"10.54926/gdt.1117813","DOIUrl":"https://doi.org/10.54926/gdt.1117813","url":null,"abstract":"The additive manufacturing method based on computer-aided design and three-dimensional printing technology, its speed, design freedom provided for the designers, the cost-effectiveness and competitive for relatively low-capacity production needs, the possibilities of achieving good quality; has been gained a popularity with the industries, including the maritime sector. The main proof of this interest is the significant increase in the number of research and development activities and scientific publications on this topic. Due to above mentioned advantages, it is inevitable for the small-marine craft industry, whose competitiveness can be made sustainable by frequently updating flexible designs, to adopt their technology to the additive manufacturing method. While it makes the design and manufacturing process of boats efficient, for getting more effective results; it requires past driven data approach on practical experience. In this study, the effect of infill density and pattern which are important parameters of the additive manufacturing method, on the tensile strength of the final product's basic mechanical properties was investigated experimentally. Tensile tests with 13 different printing pattern and 5 different infill density of polylactic acid (PLA), one of the polymers widely used based on three-dimensional printing technologies, and a test matrix consisting of five different filling densities as 10%, 25%, 50%, 75% and 100%, were performed in Dokuz Eylul University’s (DEU) Composite Laboratory. The results showed that the mechanical properties were very sensitive to these parameters, and the cubic pattern was generally effective in achieving the best mechanical properties at the investigated densities. Using this pattern and 25% density, sailboat hull with 1/5 scale was produced in DEU Institute of Marine Sciences and Technologies Additive Manufacturing Laboratory, using PLA polymer by additive manufacturing.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130607365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This work provides a benchmark study regarding the open-source panel method codes of two floating wind turbine platforms. HAMS, NEMOH, and WAMIT are compared in terms of their results, computational performance, userfriendliness, and, flexibility. WAMIT’s data is sourced from previous publications for the OC3 Hywind Spar and OC4 DeepCWind Semisubmersible. These reference values are compared to NEMOH and HAMS for wave excitation forces, added mass values, and potential damping. The study aims to help researchers to choose an open-source alternative to a validated commercial code.
{"title":"AÇIK KAYNAK KODLU PANEL METODU YAZILIMLARININ INCELENMESİ VE DEĞERLENDİRİLMESİ","authors":"M. Uçar, Emre Uzunoğlu, E. Oğuz","doi":"10.54926/gdt.1106386","DOIUrl":"https://doi.org/10.54926/gdt.1106386","url":null,"abstract":"This work provides a benchmark study regarding the open-source panel method codes of two floating wind turbine \u0000platforms. HAMS, NEMOH, and WAMIT are compared in terms of their results, computational performance, userfriendliness, and, flexibility. WAMIT’s data is sourced from previous publications for the OC3 Hywind Spar and OC4 \u0000DeepCWind Semisubmersible. These reference values are compared to NEMOH and HAMS for wave excitation \u0000forces, added mass values, and potential damping. The study aims to help researchers to choose an open-source \u0000alternative to a validated commercial code.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116391607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Additive manufacturing (AM) techniques, unlike traditional manufacturing methods with abrasion and shaping, are the production methods made by stacking the building material in layers on top of each other. In particular, AM techniques, which have experienced great advancements in the last 20 years, are divided into 7 main categories according to ISO/ASTM standards, production method and materials used. The most characteristic feature of all these techniques is that parts with complex geometries can be produced faster and at low cost. Additive manufacturing paves the way for the production of complex and lighter parts with the same strength, together with topology optimization. It is inevitable that the shipbuilding industry also benefit from additive manufacturing, which is used extensively in fields such as aviation, health and automotive. There are important feasibility studies carried out in the last 10 years with the cooperation of Loyds and shipyards as AM is actively used by various navies and research institutions. The central theme of this study is to examine the potential of additive manufacturing techniques in the shipbuilding industry. An in-depth literature review is presented including expert opinions from industry and academia, and a feasibility study is presented. From the academic point of view, fabrication of propellers, ship models and rudder structures used in academic research is examined. It has been seen that low-cost products can be fabricated by 3D printers instead of purchasing products to be used in the academic research. On the other hand, parts used in the industry are examined under two sub-categories: construction and equipment parts. In shipbuilding industry, it has been found that the usage of AM in equipment parts and some construction products will provide advantages in terms of speed and cost. Finally, various classification societies and standards are mentioned in general terms regarding the certification issue, which is one of the most fundamental problems of additive manufacturing techniques.
{"title":"Additive Manufacturing Techniques and Their Potential in the Shipbuilding Industry","authors":"Ali Alicioğlu, M. E. Yildizdag","doi":"10.54926/gdt.1119936","DOIUrl":"https://doi.org/10.54926/gdt.1119936","url":null,"abstract":"Additive manufacturing (AM) techniques, unlike traditional manufacturing methods with abrasion and shaping, are the production methods made by stacking the building material in layers on top of each other. In particular, AM techniques, which have experienced great advancements in the last 20 years, are divided into 7 main categories according to ISO/ASTM standards, production method and materials used. The most characteristic feature of all these techniques is that parts with complex geometries can be produced faster and at low cost. Additive manufacturing paves the way for the production of complex and lighter parts with the same strength, together with topology optimization. It is inevitable that the shipbuilding industry also benefit from additive manufacturing, which is used extensively in fields such as aviation, health and automotive. There are important feasibility studies carried out in the last 10 years with the cooperation of Loyds and shipyards as AM is actively used by various navies and research institutions. The central theme of this study is to examine the potential of additive manufacturing techniques in the shipbuilding industry. An in-depth literature review is presented including expert opinions from industry and academia, and a feasibility study is presented. From the academic point of view, fabrication of propellers, ship models and rudder structures used in academic research is examined. It has been seen that low-cost products can be fabricated by 3D printers instead of purchasing products to be used in the academic research. On the other hand, parts used in the industry are examined under two sub-categories: construction and equipment parts. In shipbuilding industry, it has been found that the usage of AM in equipment parts and some construction products will provide advantages in terms of speed and cost. Finally, various classification societies and standards are mentioned in general terms regarding the certification issue, which is one of the most fundamental problems of additive manufacturing techniques.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124896134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the defense forces of countries, especially the navy forces have an important place. Submarines are the cornerstone of naval forces and it has been effectively demonstrated how important a power it was in World War II. Since then, technological developments in submarines have accelerated considerably. Undoubtedly, the developments made in the propulsion systems are at the forefront of the mentioned developments. Especially with the use of AIP (Air Independent Propulsion Systems) systems, a rapid development has been observed. Many variants are applied, from classical diesel-electric submarines to closed-cycle submarines with fuel-cell technology to stirling-based submarines. Submarine applications of stirling engines, which are also used in the navies of developed countries such as Sweden and Japan, stand out. The main advantages of Stirling engines are lower refueling costs compared to Fuel cells and being quieter than the MESMA system. In addition, the fact that the exhaust gas emission is more controlled compared to internal combustion engines is among the main reasons why it is preferred. The recent development of Stirling engines and the preference of NASA's radioisotope vehicle as the main power source show how efficient the engine is without the need for oxygen and its maintenance requirement is at a minimum level. In this article, it will be discussed how the stirling engine has been developed until today and why it is preferred in submarine applications, its advantages and its future.
{"title":"Assessment of Stirling Engine Based Air Independent Propulsion Systems in Submarines","authors":"Kadir Gündüz, Yasemin ARIKAN ÖZDEN","doi":"10.54926/gdt.1113622","DOIUrl":"https://doi.org/10.54926/gdt.1113622","url":null,"abstract":"In the defense forces of countries, especially the navy forces have an important place. Submarines are the cornerstone of naval forces and it has been effectively demonstrated how important a power it was in World War II. Since then, technological developments in submarines have accelerated considerably. Undoubtedly, the developments made in the propulsion systems are at the forefront of the mentioned developments. Especially with the use of AIP (Air Independent Propulsion Systems) systems, a rapid development has been observed. Many variants are applied, from classical diesel-electric submarines to closed-cycle submarines with fuel-cell technology to stirling-based submarines. Submarine applications of stirling engines, which are also used in the navies of developed countries such as Sweden and Japan, stand out. The main advantages of Stirling engines are lower refueling costs compared to Fuel cells and being quieter than the MESMA system. In addition, the fact that the exhaust gas emission is more controlled compared to internal combustion engines is among the main reasons why it is preferred. The recent development of Stirling engines and the preference of NASA's radioisotope vehicle as the main power source show how efficient the engine is without the need for oxygen and its maintenance requirement is at a minimum level. In this article, it will be discussed how the stirling engine has been developed until today and why it is preferred in submarine applications, its advantages and its future.","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115311209","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Denizaltılarında Havadan Bağımsız Tahrik Sistemi Olarak Kullanılan MESMA Sisteminin Termodinamiksel Performans Analizi","authors":"İbrahim Özsari","doi":"10.54926/gdt.1101003","DOIUrl":"https://doi.org/10.54926/gdt.1101003","url":null,"abstract":"","PeriodicalId":414652,"journal":{"name":"Gemi ve Deniz Teknolojisi","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121744672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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