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Yayın A quasi-one-dimensional bubbly cavitating flow model and comparison with experiments(European Turbomachinery Soc-Euroturbo, 2011) Delale, Can Fuat; Başkaya, Zafer; Pasinlioğlu, Şenay; Şen, Mete; Ayder, ErkanA bubbly cavitating flow model is constructed for unsteady quasi-one-dimensional and two-dimensional nozzle flows. In each case, the system of model equations is reduced to evolution equations for the flow velocity and bubble radius and the initial and boundary value problems of the evolution equations are formulated. The rest of the flow variables are then related to the solution of the evolution equations. Nozzle flow experiments are also carried out using water. The static wall pressures are measured at different locations of the nozzle and the partial cavitation cloud cycle is recorded using a high speed camera. Results of the numerical simulations obtained for quasi-one-dimensional nozzle flows, seem to capture the measured pressure losses due to cavitation, but they turn out to be insufficient in describing the two-dimensional cavitation cloud structures, suggesting the need for two-dimensional numerical solution of the model equations.Yayın Experimental and analytical investigation of drilling in high performance hybrid composites(2019-11-09) Kayıhan, Mete; Karagüzel, Umut; Bakkal, MustafaHybrid composites produced by the addition of metal alloys to carbon fiber reinforced composites (CFRP) have superior mechanical and physical properties, excellent specific strength and high resistance to corrosion. The most commonly used machining processes in the use of hybrid materials in industry is the drilling process. After the drilling processes, due to the anisotropic properties of the CFRP material, delamination, uncut fiber and fiber pullout are observed. For this reason, the performance of CFRP after drilling operation must be the main concern. Therefore, in this study, hybrid materials were tested on factors such as stack order, drilling speed and feed rate which should be applied in hole drilling process and analysis were made on various results. The tests were performed with three-factor and three-level L9 Taguchi orthogonal experiment design due to minimize the cost and material. As a result of this study, the best stack order and drilling parameters of the hybrid composite materials was determined with many variables such as force and torque values, the required energy, surface roughness values and delamination factors.Yayın Development of turn-milling machine tool program parameters based on basic cutting geometry(2017-11-02) Berenji, Kaveh Rahimzadeh; Karagüzel, Umut; Özlü, Emre; Budak, ErhanThe turn-milling operation is a multitasking machining process that takes advantages of turning and milling operations simultaneously. However, using these two machining operations at the same time results in more complex and different cutting parameters compared to conventional turning process. In this study, the turnmilling kinematics have been modeled analytically. Using the model proposed in this study, the required parameters for a machine tool such as feed rate, workpiece, and tool rotational speed can be derived in terms of basic cutting parameters which are cutting speed, feed per tooth, radial depth of cut, and axial depth of cut.
