Studying the peculiarities of balancing of flexible double-support rotors by two passive automatic balancers placed near supports

TLDR: In this paper, a flexible double-support rotor with two passive automatic balancers of pendulum, ball or roller type was constructed and the system of differential equations, which describes the motion of a rotor machine, was obtained.

Abstract: A discrete N­mass model of a flexible double­support rotor with two passive automatic balancers of pendulum, ball or roller type was constructed. Automatic balancers are placed near supports. The system of differential equations, which describes the motion of a rotor machine, is obtained. The primary (sustained) motions of a system as the motions, in which automatic balancers eliminated displacements of a rotor in supports, were found. It is shown that on the primary motions, the total imbalances of a rotor and AB, reduced to two correction planes (supports), equal zero. It was proposed to examine the stability (of the family) of sustained motions by generalized coordinates, which set the displacement of a rotor in the supports and by dynamic variables that equal total imbalances of a rotor and AB in two correction planes. We obtained differential equations, which describe the change in these variables that describe the process of self­balancing. By the analysis of differential equations of the motion of a system it was established that: – on the primary motions, AB eliminate rotor deflections and vibrations in elastic viscous supports, but do not remove shaft deflections in non­supporting points; – on the primary motions elastic viscous supports are conditionally converted into hinge supports; – shaft deflections in non­supporting points and the primary motions change with the change in angular speed of rotation of the rotor; – primary motions exist at a certain distance of the speed of rotation of the rotor from the critical speeds of flexible rotor rotation with the hinge supports instead of elastic viscous supports; – at the speeds of rotation of a rotor shaft close to any of these speeds, the conditions of existence of the primary motions are disrupted because shaft deflections theoretically grow to infinity and the balancing capacity of AB is not sufficient for the compensation for the imbalances of the rotor; – in practice these deflections are limited and, therefore, proper selection of the balancing capacity of AB can ensure existence of primary motions at all speeds of rotation of rotor.