Sert, Cüneyt
Ozer, Mehmet Bulent
In the last decade, there is a renewed interest in the integration of a sloshing tank into structural systems to decrease the vibrations of the structure. The purpose of this study is to try different numerical simulation programs for further use in studies in evaluation of the effectiveness of the sloshing tank absorbers for structural systems. The programs chosen for sloshing simulations are COMSOL Multiphysics, ANSYS CFX and ANSYS-FLUENT. In the numerical simulations, the free surface shape during sloshing will be simulated under small and large amplitude sinusoidal displacements. The results obtained using different software will be compared with the results of the experiments reported in literature. Since the purpose is to use the sloshing forces on the container to decrease the structural response, the total force on the container walls is calculated and compared with the reported experimental results. The dynamics of a container coupled with the a structural model is simulated and forces applied on the container walls are analyzed in the frequency domain which is important in understanding the tuning of the vibration absorber. To the best of authors' knowledge, in a fluid-structure coupled system the frequency domain analysis of the container wall forces at varying amplitudes of sinusoidal excitation is not presented in literature. The results showed even though higher harmonic forcing magnitudes increase with increasing base motion, the fundamental harmonic component does not change significantly.


Numerical investigation of the effect of the Rushton type turbine design factors on agitated tank flow characteristics
Yapici, Kerim; Karasözen, Bülent; Schaefer, Michael; Uludağ, Yusuf (2008-08-01)
The turbulent flow field in a mixing tank generated by the six-blade Rushton turbine impeller is predicted by using computational fluid dynamics. The governing differential equations of the fluid flow are approximated by an algebraic set of equations through a finite volume method, while large eddy simulation is employed to handle the effects originating from the turbulence. The relative motion between the rotating impeller and the stationary baffle is considered by clicking mesh method. The effects of impe...
Analysis and control of complex flows in U-bends using computational fluid dynamics
Güden, Yiğitcan; Yavuz, Mehmet Metin; Department of Mechanical Engineering (2014)
Analysis and control of flow structure is crucial in the sense that the increase in the ratio of inertial and centrifugal forces to viscous forces destabilizes the flow and creates a three-dimensional complex flow consisting of stream wise parallel counter-rotating vortices, so-called Dean vortices. In addition, due to the curvature in U-bends, in line with these vortices, a high level of turbulence is detected, which is quite critical in considering noise problems and structural failures. In this thesis, c...
Application of numerical shape optimization to the runner blades of a francis turbine
Yalılı, Mehmet; Aksel, Mehmet Haluk; Department of Mechanical Engineering (2015)
The multi-objective design of hydraulic turbines using computational fluid dynamics software has been an important subject in turbomachinery area recently. Researches focus especially on obtaining higher turbine efficiency by the improvement of runner shapes. Thus in the present study, a multi-objective shape optimization procedure was applied to improve the runner blade shapes of a small Francis turbine named as GAMM turbine which was selected from the literature. CFD computations as well as blade generati...
Theory of impurity induced lattice distortions in the normal phase of charge density wave systems
Turgut, Sadi (1994-05-01)
A phenomenological Ginzburg-Laundau theory is applied to the normal phase of one-dimensional charge-density-wave systems with a finite concentration of impurities. It is found that the interaction between the impurities and the highly polarizable electron gas leads to a strong and oscillatory impurityimpurity interaction, which in turn leads to ordered impurity arrangements and to sizeable periodic lattice distortions. The effect is very strongly dependent on the charge of the impurities, their concentratio...
Estimation of effective parameters and operational response of tuned vibration absorbers
Özden, Hasan Can; Özgen, Gökhan Osman; Department of Mechanical Engineering (2019)
In this study, swing up and stabilization of on/off type of cold gas thruster driven inverted pendulum is accomplished. First, pulse width modulator (PWM) design method is generated to obtain quasi-linear thrust output from on/off type of thruster. Than, single axis angle controller is designed. Designed angle controller and PWM scheme are tested and verified on single axis angle control test setup. Finally, an other freedom is attached to single axis test setup and rotary inverted pendulum (Furuta Pendulum...
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