|
|
Experimental study of fluid-induced instabilities in journal bearings
Stifter, Jan ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
Presented diploma thesis deals with experimental study of fluid induced instabilities which occur in rotating machinery with journal bearings. The first part describes the oil whirl and oil whip instabilities. It also gives an example of optical methods used for observation of journal bearings. Next part is dedicated to modifications of an existing test rig that were necessary for carrying out experiments. Finally, there are presented results of experiments that define the effect of initial conditions on appearance of instabilities.
|
|
|
Experimental study of journal bearings dynamics
Tkadlec, Josef ; Vimmr, Jan (referee) ; Omasta, Milan (advisor)
This work deals with experimental analysis of fluid film instability in rotor bearing systems stored in hydrodynamic plain bearings with focus on bearing surface modification. The experiments were performed on a journal bearing dynamics simulator. The aim was to determine the influence of individual operating parameters on the occurrence and course of turbulence instability. The emphasis here was on the effect of surface micro textures. The work also included the preparation of textured samples. Experiments were divided into experiments monitoring the influence of temperature, pressure, bearing geometry and surface modification. The output of the individual experiments were the values of the threshold speed of formation and termination of instability or the magnitude of the amplitude depending on the above described parameters. These values were plotted in graphs. This data was then confronted with previously published articles. The results showed that instabilityin rotor systems is very sensitive to temperature, pressure and bearing geometry changes. The fundamental influence on the unstable behavior of the rotor system has been demonstrated by the use of textured surfaces, where the threshold speed was significantly shifted to a higher speed range compared to the non-textured bearing.
|
|
|
Rotordynamics of Modern Turbocharger
Fryščok, Tomáš ; Dundálek, Radim (referee) ; Kaplan, Zdeněk (referee) ; Píštěk, Václav (advisor)
This dissertation thesis consists rotordynamics of modern turbocharger. First part begins with prediction of critical speed, prediction of onset instability of oil whirl and oil whip by XLTRC2 and comparison with measured data (Cascade diagram, shaft motion, FFT analysis). List of measurement method for the detection of the natural frequency of turbocharger (EMA). Create software for long term monitoring and recording and output data size reduction. Detection of critical speed by defined measurement methodology without using software simulation with measured data from the Cascade diagram, move the rotor shaft motion in the bearing, FFT analysis and results from measurements of natural frequencies. Comparison of predicted data (critical speed, prediction of onset instability) program XLTRC2 with the values measured by this approach measurement (waterfall diagram, shaft motion, FFT analysis)
|
|
|
Verification of rotor model properties for sleeve bearings
Šály, Timotej ; Hnidka, Jakub (referee) ; Klusáček, Stanislav (advisor)
This bachelor thesis deals with a professional research in the field of sleeve bearings and their diagnostic disorders. It describes the recognized methods of identification and technical diagnosis of these errors. Furthermore, it describes the features and possibilities provided by the rotor model RK4 in the simulation of sleeve bearings. Moreover, the thesis deals with the development of a laboratory task for students to demonstrate the diagnostic fault of oil whirl.
|
|
|
Verification of rotor model properties for sleeve bearings
Šály, Timotej ; Hnidka, Jakub (referee) ; Klusáček, Stanislav (advisor)
This bachelor thesis deals with a professional research in the field of sleeve bearings and their diagnostic disorders. It describes the recognized methods of identification and technical diagnosis of these errors. Furthermore, it describes the features and possibilities provided by the rotor model RK4 in the simulation of sleeve bearings. Moreover, the thesis deals with the development of a laboratory task for students to demonstrate the diagnostic fault of oil whirl.
|
|
|
Experimental study of journal bearings dynamics
Tkadlec, Josef ; Vimmr, Jan (referee) ; Omasta, Milan (advisor)
This work deals with experimental analysis of fluid film instability in rotor bearing systems stored in hydrodynamic plain bearings with focus on bearing surface modification. The experiments were performed on a journal bearing dynamics simulator. The aim was to determine the influence of individual operating parameters on the occurrence and course of turbulence instability. The emphasis here was on the effect of surface micro textures. The work also included the preparation of textured samples. Experiments were divided into experiments monitoring the influence of temperature, pressure, bearing geometry and surface modification. The output of the individual experiments were the values of the threshold speed of formation and termination of instability or the magnitude of the amplitude depending on the above described parameters. These values were plotted in graphs. This data was then confronted with previously published articles. The results showed that instabilityin rotor systems is very sensitive to temperature, pressure and bearing geometry changes. The fundamental influence on the unstable behavior of the rotor system has been demonstrated by the use of textured surfaces, where the threshold speed was significantly shifted to a higher speed range compared to the non-textured bearing.
|
|
|
Experimental study of fluid-induced instabilities in journal bearings
Stifter, Jan ; Polach, Pavel (referee) ; Omasta, Milan (advisor)
Presented diploma thesis deals with experimental study of fluid induced instabilities which occur in rotating machinery with journal bearings. The first part describes the oil whirl and oil whip instabilities. It also gives an example of optical methods used for observation of journal bearings. Next part is dedicated to modifications of an existing test rig that were necessary for carrying out experiments. Finally, there are presented results of experiments that define the effect of initial conditions on appearance of instabilities.
|
|
|
Rotordynamics of Modern Turbocharger
Fryščok, Tomáš ; Dundálek, Radim (referee) ; Kaplan, Zdeněk (referee) ; Píštěk, Václav (advisor)
This dissertation thesis consists rotordynamics of modern turbocharger. First part begins with prediction of critical speed, prediction of onset instability of oil whirl and oil whip by XLTRC2 and comparison with measured data (Cascade diagram, shaft motion, FFT analysis). List of measurement method for the detection of the natural frequency of turbocharger (EMA). Create software for long term monitoring and recording and output data size reduction. Detection of critical speed by defined measurement methodology without using software simulation with measured data from the Cascade diagram, move the rotor shaft motion in the bearing, FFT analysis and results from measurements of natural frequencies. Comparison of predicted data (critical speed, prediction of onset instability) program XLTRC2 with the values measured by this approach measurement (waterfall diagram, shaft motion, FFT analysis)
|
|
|
Judgement of Possibilities of Decrease of Vibration Magnitude of Forced Response by Actuating Kinematic Excitation Effect
Markopoulos, A. ; Ondrouch, Jan ; Ferfecki, Petr
Summary: The task is to determine time history of a kinematic excitation so that after the initial transient component dies out, the magnitude of displacement a kinematicaly excited system has been lower than the magnitude of the system without kinematic excitation. The best solution of the investigated problem can be calculated by means of a procedure using minimization of the functional. However, numerical simulations shows that due to complexity of analysis proposed approach is not useful for solving systems with more than one of degree of freedom. They also tell that the best approaches to decrease a vibration magnitude of a rotor system supported by hydrodynamic bearings are methods using linearization equation of motion.
|
guest ::
