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Vibration control of rotors mounted in hydrodynamic bearings lubricated with magnetically sensitive oil by changing their load capacity

Zapoměl Jaroslav, Ferfecki Petr

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 6

art. no. e137988

EN

Rotors of rotating machines are often mounted in hydrodynamic bearings. Loading alternating between the idling and full load magnitudes leads to the rotor journal eccentricity variation in the bearing gap. To avoid taking undesirable operating regimes, its magnitude must be kept in a certain interval. This is offered by the hydrodynamic bearings lubricated with smart oils, the viscosity of which can be changed by the action of a magnetic field. A new design of a hydrodynamic bearing lubricated with magnetically sensitive composite fluid is presented in this paper. Generated in the electric coil, the magnetic flux passes through the bearing housing and the lubricant layer and then returns to the coil core. The action of the magnetic field on the lubricant affects the apparent fluid viscosity and thus the position of the rotor journal in the bearing gap. The developed mathematical model of the bearing is based on applying the Reynolds equation adapted for the case of lubricants exhibiting the yielding shear stress. The results of the performed simulations confirmed that the change of magnetic induction makes it possible to change the bearing load capacity and thus to keep the rotor journal eccentricity in the required range. The extent of control has its limitations. A high increase in the loading capacity can arrive at the rotor forced vibration’s loss of stability and induce large amplitude oscillation.

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Wyważanie wirnika sztywnego z luzem między łożyskiem i obudową

Zachwieja J.

Modelowanie Inżynierskie

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2010

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T. 9, nr 40

265-272

PL

W pracy przedstawiono wyniki analizy ruchu wirnika w sytuacji, gdy promieniowe ustalenie łożyska w obudowie nie jest prawidłowe. Wyznaczoną doświadczalnie trajektorię przemieszczenia czopa wału filtrowano metodą EMD, natomiast charakter drgań określono przy wykorzystaniu transformacji Hilberta-Huanga. Zbadano również efektywność wyważania wirnika na podstawie zmodyfikowanej metody współczynników wpływu, optymalizującej amplitudy drgań łożysk przy występowaniu anizotropowości zewnętrznej układu.

EN

The occurrence of the clearance between the outer bearing ring and casing is usually the result of progressing wear and tear of components or improper assembling that takes place very often at industrial conditions. The work presents the results of the rotor motion analysis when radial setting of the bearing in the casing is improper. The shaft journal displacement trajectory determined experimentally was filtered by the EMD method (empirical mode decomposition), whereas the vibration nature was determined using the Hilbert-Hunag's transformation. The rotor balancing efficiency was examined also based on the modified impact factor method, optimising the amplitudes of bearing vibrations at the presence of external system anisotropy.

3

Aktywne tłumienie drgań rezonansowych sztywnego wirnika podpartego w łożyskach o zarysach niekołowych w przypadku wymuszenia kinematycznego

Starczewski Z.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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2002

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z. 60 [197]

555-560

EN

In the paper the possibility of damping of resonant vibration of a rigid rotor supported on pericycloidal journal bearings with the multiplication factor Kn=3 (three-lobe bearings) is discussed. The effect of application of 2 and 3 pairs of magnetic actuators on limitting resonance amplitudes is examined. As the excitation motion of the fundament (kinematic excitation) is assumed. Exemplary diagrams showing resonant displacements of the rotor and concluding remarks are included in the paper.

4

Damping of resonant vibration of a rigid rotor supported on journal bearings with electrofluid

Starczewski Z

Mechanics and Mechanical Engineering

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2001

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Vol. 5, nr 2

121-126

EN

The paper is concerned with the problem of damping of resonant vibration in a rigid rotor system supported on journal bearings. The equations of motion of a such system are derived. Kinematic excitation is under investigation. Appropriate diagrams of amplitude and frequency in dependence of the system parameters as well as results and concluding remarks has been included.

5

Wpływ wzajemnego położenia panewek łożysk o zarysach niekołowych na zmianę progu samowzbudzenia wirnika

Starczewski Z.

Vibrations in Physical Systems

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2000

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Vol. 19

258--259

6

Aktywne tłumienie drgań sztywnego wirnika łożyskowanego ślizgowo w przypadku wymuszenia kinematycznego

Starczewski Z.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

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1999

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z. 52 [174]

221-226

EN

In the paper possibility of active stabilization of a rigid rotor supported on journal-bearings is presented. Electromagnetic actuators are applied in the method. The system is subjected to kinematic excitation and analysed with respect to different voltages, bearing gaps, rotor masses, and excitation frequencies. Appropriate resonant diagrams are presented.