Abstract
Dynamic modeling, simulation and analysis of hydraulic recessed journal bearings are proposed in this work, including simulation and analysis. For hydraulic journal bearing systems, the dynamic model can be represented as the equation of motion of the shaft. The mathematical model is appropriately built for hydraulic recessed journal bearings and shaft motion behavior is simulated under different controllable factors by using MATLAB/Simulink. In the dynamics derivation, basic model of hydraulic journal bearings will be introduced and applied to the modeling of recessed journal bearing systems. In the basic model derivation, firstly Reynolds equation for oil film will be derived, and secondly boundary conditions are substituted to derived oil film pressure field equation. Thirdly, the integral of oil film pressure field with respect to the shaft surface can obtain the oil film force acting on the shaft, and finally the equation of motion can be derived. In addition, the coefficients relations in the equation of motion can be received. In the derivation of recessed journal bearing dynamic model, the coefficients in the equation of motion can be simplified and defined as hydrostatic stiffness, hydrodynamic stiffness and squeeze damping considering static and dynamic properties of oil film. In the literature, a dynamic model will be derived based on several assumptions but that are only for ideal cases. Therefore, some of the assumptions must be revised and a controllable dynamic model will be proposed in order to meet the real operation conditions of recessed journal bearings. In the simulation works, the relations between coefficients and eccentricity are illustrated and the shaft motion trajectories are presented. The coefficients and eccentricity plot can be used to explain the reason why the coefficients in the equation of motion can be simplified. Besides, use controllable dynamic model to simulate the shaft motion trajectories at different rotational speeds and supply pressure while applying an external force on the shaft. Simulation results show the shaft motion behavior and the system stability situations of recessed journal bearings.