Research on two-phase thermo-hydrodynamic lubrication performance considering bubble dynamics

Abstract

Gas-liquid two-phase fluid in the lubrication gap exist in many important engineering tribo-pairs. Based on the Reynolds equation, the bubble dynamics equation, and the full energy equation for two-phase fluids, the thermo-hydrodynamic lubrication problem in the lubrication gap is investigated. The evolution of the fluid phase composition with operating time and its impact on the thermodynamic properties are studied using the developed model. The mechanisms by which sliding velocity, clearance, surface dilatational viscosity, surface tension, and initial gas volume fraction affect two-phase fluid lubrication behavior are evaluated. The results show that hydrodynamic pressure-driven bubbles eventually condense in the dispersion area and have a major impact on the temperature distribution. Velocity and clearance affect the gas-phase expansion region and initial formation location in the steady state, respectively. The pressure amplitude, bubble expansion, and horizontal and vertical gas phase expansion in the dispersion zone were affected differently by surface dilatational viscosity and surface tension. It becomes difficult to preserve the initial gas-phase composition inside the pressure convergence zone when bubble migration is taken into account, which may be crucial for establishing gas-liquid two-phase lubrication.