Experimental investigation of dynamic properties of an active journal bearing

A flexible sleeve can be considered as a new feature of the proposed active journal bearing. Variation of the oil pressure in the chamber located under the sleeve causes deformation of the sleeve and consequently changes the geometry of the oil film as well as the pressure distribution of the oil film. Hence, the dynamic characteristics of the bearing can be varied without stopping the operation of the rotor. Therefore, by changing the chamber pressure based on either pre-calculation or on-line processing, the dynamic response of the rotor could be controlled. This paper offers a detailed description of a laboratory installation furnished with the active bearing and the conducted experimental investigation. This experimental investigation allowed the developed mathematical models of the laboratory installation to be verified. Results of the numerical analysis of the dynamic response (stability of equilibrium position and forced response due to the residual imbalance) of the laboratory installation by means of both the linear and the non-linear mathematical model are presented. This analysis was carried out in both the configuration parameters domain and the angular speed domain. These analytical predictions are compel-ed with results of the experimental investigation. Numerical calculations based on the mathematical model have shown good agreement with experimental results both qualitatively and quantitatively. Numerical calculations and the experiments indicate that the stability of the rotor-bearing system is sensitive to the chamber pressure of the active journal bearing. By applying an appropriate constant chamber pressure, the system stability can always be improved. (C) 2000 Academic Press.