Linking rigid multibody systems via controllable thin fluid films

Abstract

This work deals with the mathematical modelling of multibody systems interconnected via thin fluid films. The dynamics of the fluid films can be actively controlled by means of different types of actuators, allowing significant vibration reduction of the system components. In this framework, this paper gives a theoretical contribution to the combined fields of fluid–structure interaction and vibration control. The methodology is applied to a reciprocating linear compressor, where the dynamics of the mechanical components are described with help of multibody dynamics. The crank is linked to the rotor via a thin fluid film, where the hydrodynamic pressure is described by the Reynolds equation, which is modified to accommodate the controllable lubrication conditions. The fluid film forces are coupled to the set of nonlinear equations that describes the dynamics of the reciprocating linear compressor. The system of equations is numerically solved for the case when the system operates with conventional hydrodynamic lubrication and for several cases of the bearing operating under controlled hybrid lubrication conditions. The analysis of the results is carried out with focus on the behaviour of the journal orbits, maximum fluid film pressure and minimum fluid film thickness.