Mekatronik Mühendisliği Bölümü
https://hdl.handle.net/20.500.12418/290
2024-03-29T06:43:13ZExperimental and Numerical Investigation of the Control of the Flow Structure on Surface Modified Airfoils
https://hdl.handle.net/20.500.12418/14700
Experimental and Numerical Investigation of the Control of the Flow Structure on Surface Modified Airfoils
Öztürk,Adnan; Çoban, Mehmet; Koca, Ferhat
In this study, experimental and numerical flow analysis was performed on three different blade profiles with a chord length of 165 mm using passive flow control method. The first of the airfoil is the standard NACA 0018 profile. The second airfoil type has a NACA 0018 profile with a gap in the suction surface. The last airfoil is the NACA 0018 profile which is 66% of the trailing edge cut from the chord length. All airfoil profiles were analyzed at the Reynolds number, Re=2x104, and angles of attack α=0o, 5o, 10o, 12o and 14o in both experiment and numerical studies. The experiments were carried out using the Particle Image Velocimetry (PIV) method in a closed-loop open water channel, and the time-averaged velocity vectors, streamlines, and vorticity contours of the flow field were obtained. Subsequently, numerical analyses were performed using the ANSYS Fluent package program, one of the Computational Fluid Dynamics (CFD) programs used frequently in the literature. The streamlines and pressure contours of the airfoil profiles have been compared visually at the same Re and different angles of attack. In addition, according to the angle of attack of the airfoil profiles, lift coefficient CL, drag coefficient CD, and the ratio of lift coefficient to drag coefficient CL/CD graphs were presented. It has been shown that the gap on the airfoil at high attack angles caused changes in lift (up to 0.7) and drag (up to 0.15). These features can allow these models to be used for different purposes in the aerodynamics field.
2023-01-01T00:00:00ZExperimental investigation of the effects of boron oil additive in internal combustion engine
https://hdl.handle.net/20.500.12418/14529
Experimental investigation of the effects of boron oil additive in internal combustion engine
Karataş, Ömer; Yüksel, Tahsin
Using additives to engine oils increases engine performance, extending engine maintenance life, boosting the competitiveness of mineral-based oils technically and economically. In this study, the effects of liquid boron oil additive added to mineral-based 10 W-40 engine lubricating oil used in a single-cylinder diesel engine were investigated. 15 % of the engine oil volume was added to the engine as an additive. Experimental studies were carried out at three different engine speeds (i.e., 1500, 1750, and 2000 rpm). The engine, on which no changes were made, was first run with mineral lubricating oil, and then the experiments were repeated with mineral lubricating oil with 15 % boron additive. In the studies, engine torques, specific fuel consumption, and exhaust emissions (HC, CO, CO2, and NOx) were evaluated. In addition, the effects of operating the engine for 100 h without adding any additives and with oil additives containing 15 % boron were also investigated. It was found that engine torque and EGT increased while BSFC, CO2, HC, and NOx decreased in boron-added mineral lubricating oil for all revolutions. In addition, there was a general decrease in CO emissions. In-cylinder SEM images and oil analyses, which were operated with a 15 % boron additive to the engine oil, showed that the boron additive positively affected the engine.
2023-01-01T00:00:00ZAutomatic Detection and Mapping of Dolines Using U-Net Model from Orthophoto Images
https://hdl.handle.net/20.500.12418/14394
Automatic Detection and Mapping of Dolines Using U-Net Model from Orthophoto Images
Polat, Ali; Keskin, İnan; Polat, Özlem
A doline is a natural closed depression formed as a result of karstification, and it is the most common landform in karst areas. These depressions damage many living areas and various engineering structures, and this type of collapse event has created natural hazards in terms of human safety, agricultural activities, and the economy. Therefore, it is important to detect dolines and reveal their properties. In this study, a solution that automatically detects dolines is proposed. The proposed model was employed in a region where many dolines are found in the northwestern part of Sivas City, Turkey. A U-Net model with transfer learning techniques was applied for this task. DenseNet121 gave the best results for the segmentation of the dolines via ResNet34, and EfficientNetB3 and DenseNet121 were used with the U-Net model. The Intersection over Union (IoU) and F-score were used as model evaluation metrics. The IoU and F-score of the DenseNet121 model were calculated as 0.78 and 0.87 for the test data, respectively. Dolines were successfully predicted for the selected test area. The results were converted into a georeferenced vector file. The doline inventory maps can be easily and quickly created using this method. The results can be used in geomorphology, susceptibility, and site selection studies. In addition, this method can be used to segment other landforms in earth science studies.
2023-01-01T00:00:00ZAISI430/DUROSTAT500 TIG kaynaklı birleştirmesinin kırık yüzey morfolojisinin incelenmesi
https://hdl.handle.net/20.500.12418/14356
AISI430/DUROSTAT500 TIG kaynaklı birleştirmesinin kırık yüzey morfolojisinin incelenmesi
Aydın, Sinan
Bu çalışmada AISI430 ve DUROSTAT500 çelikleri çift taraflı TIG kaynak yöntemiyle
birleştirilmiştir. Birleştirmelerin mikro yapı, çekme ve çentik darbe testlerinin kırılma sonrası kırık yüzey
morfolojileri değerlendirilmiştir. Akım şiddetinin yoğunluğu ile tam bir nüfuziyet sağlanmıştır. Farklı iki
çelik TIG yöntemi ile başarılı bir şekilde birleştirilmiştir. Yüksek akım yoğunluğu ile Cr, C ve Ni
elementlerinin difüzyonu meydana gelmiştir. Çekme ve çentik darbe testi sonrası numunelerin kırık
yüzeylerinde gevrek kırılma tespit edilmiştir.
2023-01-01T00:00:00Z