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Reducing vibration amplitude by means of damping control in support elements of flexible rotors
Zapoměl, Jaroslav ; Pešek, Luděk ; Viet, La Duc ; Savin, L. ; Kozánek, Jan
Damping in the supports of rotors loaded by unbalance has influence on the vibration amplitude and critical speed of rotating machines. To minimize the oscillation amplitude during the rotor acceleration and running over the critical velocity, the damping in the support elements should be reduced. The reduction cannot be sudden but must be distributed in time. This requires to determine the proper moment of time when to start this manipulation and the time of its duration. This paper deals with investigation of the possibility of utilization of controllable squeeze film dampers lubricated by magnetorheological oil to accomplish this manipulation.
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Concepts of reducing the forces transmitted between the rigid rotor and its frame based on magnetorheological damping devices
Zapoměl, Jaroslav ; Ferfecki, Petr ; Kozánek, Jan
A usual technological solution how to reduce forces transmitted between the rotor and its stationary part is to apply a flexible suspension with damping devices placed between the rotor and its casing. Optimum performance of the constraint damping elements can be achieved if their damping effect is controllable. As the control depends only on speed of the rotor rotation that does not vary rapidly the semiactive devices based on utilization of the magnetorheological phenomenon can be used for this purpose. Then the damping force is controlled by the change of electric current generating magnetic flux passing through the layer of the magnetorheological lubricant. Three concepts of their arrangement were studied: magnetorheological dampers with only one layer of the magnetorheological liquid and dampers with two separated layers formed by the normal oil and magnetorheological lubricants in the serial and parallel arrangements.
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