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Balancing turbines rotor
Peterka, Zdeněk ; Kracík, Petr (referee) ; Fiedler, Jan (advisor)
This bachelor’s thesis is specialized search dealing with issues of balancing turbines rotors. The first part of this work is devoted to general problems of balancing turbines rotors and basics of balancing turbines rotors. In the second part of this thesis there is a documentation of balancing device so-called „shelter“. The third part already discussed about the very processes of balancing turbines rotors. In the last part there two examples of practical balancing turbines rotors.
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Analysis of vibration of rotors with a thick rigid disc on the overhanging end supported by hydrodynamic bearings and loaded by uncertain unbalance effects
Zapoměl, Jaroslav ; Ferfecki, P. ; Molčan, M. ; Kozánek, Jan
Rotors of some rotating machines consist of a shaft and a rigid disc attached to its overhanging end. Because of manufacturing and assembling inaccuracies, the disc is unbalanced. In general case, the disc principal axis of inertia deviates from the shaft axis (both axes are skew lines) and the disc center of gravity is not situated on the shaft center line. Then the disc inertia effects are the source inducing the rotor lateral vibration. As magnitude of parameters specifying the disc unbalance is uncertain, application of an adequate method is required to perform the analysis. In addition, if the rotor is supported by hydrodynamic bearings, their nonlinear properties lead to rising complexity of the system vibration and to reducing its predictability. In the presented paper, the motion equation of a rigid disc has been derived. The shaft was represented by a beam body that was discretized into finite elements. The stiffness and damping parameters of the hydrodynamic bearings were linearized in vicinity of the rotor equilibrium position. Then vibration of the rotor is governed by a set of linearized motion equations. The fuzzy numbers were applied to consider uncertainty of the disc unbalance parameters. The presented procedure provides the approach to computational analysis of rotating machines with the rotor having a disc attached to its overhanging end and the geometrical, mechanical, or technological parameters of which have uncertain values.
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Balancing turbines rotor
Peterka, Zdeněk ; Kracík, Petr (referee) ; Fiedler, Jan (advisor)
This bachelor’s thesis is specialized search dealing with issues of balancing turbines rotors. The first part of this work is devoted to general problems of balancing turbines rotors and basics of balancing turbines rotors. In the second part of this thesis there is a documentation of balancing device so-called „shelter“. The third part already discussed about the very processes of balancing turbines rotors. In the last part there two examples of practical balancing turbines rotors.
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Analýza stability rovnovážné polohy a odezvy rotorů uložených v kapalinných ložiskách a majících kotouč ponořený v nesmáčivé kapalině
Zapoměl, Jaroslav
In a number of technological applications the rotors supported by fluid film bearings have the discs submerged in various liquids. Lateral vibration of such rotors is significantly influenced by their interaction with the medium in the surrounding space. A computer modelling method represents an important tool for investigation of their behaviour. The approach to analysis of vibration of small amplitudes of structures submerged in liquids is based on modification of the Navier Stokes equations leading to the Laplace one. The fluid film bearings are usually implemented into the computational models by means of nonlinear force couplings. The pressure distribution in the full oil film is governed by a Reynolds equation and in cavitated areas the pressure remains constant. The motion of a rotor supported by short hydrodynamic bearings, excited by imbalance forces, and having a disc submerged in inwettable liquid was investigated.
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Postup pro zkoumání stability rovnovážné polohy a nelineární odezvy rotoru uloženého v kapalinných ložiskách a majícím kotouč ponořený v neviskózní, nesmáčivé kapalině
Zapoměl, Jaroslav
Lateral vibration of rotors is significantly influenced by their supports and by their interaction with the medium in the ambient space. If the disc of the rotor is submerged in a liquid and if it vibrates, the pressure field is induced and the liquid acts by a force on the wall of the disc. It is assumed that the disc performs oscillations only with small amplitudes and it enables to describe the produced pressure field by a Laplace's equation and by the relation for the boundary conditions. The liquid is inwettable and it means that it does not lean to the disc surface and therefore no tangential forces acting on the disc are produced. The resulting force is obtained by integration of the pressure distribution around the circumference and along the height of the submerged part of the disc. Its components are proportional to the disc accelerations and it implies that the negatively taken coefficients of proportionality can be considered as additional masses.
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PROPOSITION OF THE DIFFERENTIAL FEEDBACK CONTROL OF ROTOR’S POSITION FOR CONTACTLESS SUPPORT
Kozánek, Jan ; Synek, L. ; Sýkora, Petr
This paper proposes a differential method for the position control of electromagnetic actuator. The differential method is frequently used by active magnetic bearing in industrial application too. The controller is consisted of position regulator and two current regulators with auxiliary differential part, where is counted a difference between biases current and position current. Thus the controller contains a current feedback and a position feedback. The current feedback is used as current control into exciting coil and the air-gap is measured by an eddy current position sensor. The position stabilization of the contactless rotor is provided by suitable analogue regulator.
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