Theoretical Evaluation of Capacitance, Capacitive Reactance, Resistance and Their Effects on Performance of Hydrodynamic Journal Bearings

A theoretical approach is developed to determine capacitance, capacitive reactance, active resistance, and impedance of hydrodynamic journal bearings under different conditions of operation. It has been established that the bearing capacitance increases with eccentricity and L/D ratios but reduces with increase in clearance ratio. On the contrary, resistance and capacitive reactance of a bearing increase with the clearance ratio but reduce with increase in the eccentricity and L/D ratios. However, the bearing impedance is more affected by the resistance than the capacitive reactance. The bearing behaves like a capacitor till the ratio of capacitive reactance to active resistance is less than unity, and acts like a variable resistor as this ratio exceeds unity. This analysis has a potential to analysis safe load carrying capacity at different speeds of operation by determining the bearing capacitance. Also, this may act as a guide to select the bearing design parameters for safe and reliable operation of a hydrodynamic journal bearing.