Determining Changes in the Engagement of Screw Rotors Due to Transmission Error

Abstract

As a rule, the structural analysis of screw compressors during their design comes down to determining the geometric dimensions of the screws, the position of their window edges, as well as the gas forces acting on the compressor rotors. The latter determine the loads on the compressor bearings and affect vibration of the rotors and the compressor as a whole. Their effect plays the dominant role but not the only one. To create a mathematical model describing the vibration state of rotors, determining all additional forces acting on the compressor rotors that arise in the course of its operation under normal operating conditions is also required. These include the manufacturing inaccuracies causing skewing and bending of the rotor axles, as well as contact forces caused by the interaction of rotors due to their deviation from the nominal position. The latter are the least studied and, as a rule, are typical only for oil-flooded screw compressors with no rotor synchronisation mechanism. This article is devoted to the determination of rotor dynamics and the forces caused by rotor teeth engagement. In future, its results will serve as a basis for developing a rotor vibration state model. Meanwhile, the analysis of results obtained already at the current research stage allows to decrease their impact and effect.