Influence of the Mechanical Seals on the Dynamic Performance of Rotor-Bearing Systems

Abstract

In this paper, to consider the effects of mechanical seals, a lumped-mass model and the transfer matrix method are used to establish the equations for the dynamics performance of rotor-bearing system. The general inverted iteration method is also used to solve the eigenvalue problem of these equations. To check the response of the rotor-bearing system under unbalance motivation, the Gauss method is used to calculate the dynamic response of the constrained vibration. The results, based on the dynamic properties calculation of a typical mechanical spiral seal, such as stiffness coefficients and damping coefficients, exert the influence of the mechanical seal on the rotor-bearing system of the high-speed machinery. Meanwhile, some structure parameters that may affect the dynamic performance and forced vibration under unbalance motivation of the rotor-bearing system considering mechanical seals are analyzed in the paper. The analysis results show that the mechanical seal more or less has effects on the rotor-bearing system. The mechanical seal has much more effects on the flexible rotor-bearing system than on the rigid one. For instance, in a certain case, if the effects of the mechanical seal were taken into account, the systems critical speed may increase by 70–80%.