Data driven performance prediction and optimization model for a nano-lubricated multi-pad active journal bearing using modified Krieger–Dougherty viscosity and couple stress models

High demand for optimum bearing operation with suppressed vibration amplitudes and enhanced stability has led to the advent of active/controllable fluid film bearings. Integration of active bearing technology in turbomachinery applications facilitates reduced energy losses and supports resource-efficient, sustainable operation. In the present study, a novel form of active journal bearing with multiple adjustable elements is designed to modify the hydrodynamic behavior of rotor bearing systems. Along with pad adjustments, improved bearing performance will be attained due to the presence of Titanium dioxide nanoparticle additives in oil. Theoretical modelling is performed using modified Krieger-Dougherty viscosity method to predict the relative viscosities of nano-Titanium dioxide oil by considering the volume fraction and aggregate size of nanoparticles. A variable viscosity method is utilized to evaluate the steady state characteristics in a multi-pad adjustable bearing operated with nano-Titanium dioxide lubricant. Using Response Surface Methodology approach, process parameters are mapped to the output parameters to identify the operating zone of the adjustable fluid film bearing and nature of response variation. Further, appropriate weights are assigned to three output parameters to identify the optimum combination of input parameters to attain an improvement in bearing performance characteristics. In the normal operating zone, pad adjustments in negative radial and tilt adjustments play a significant role in influencing the peak bearing pressures and loa capacity.