Study on the bubbly lubrication of journal bearings at various shear rates and temperatures

• Constitutive equation of bubbly oil including shear rate and temperature is built.
• Modified lubrication model of journal bearings with bubbly oil is developed.
• Bubbly lubrication of bearings is studied at relatively low to high shear rates.
• Aeration effects on bubbly oil viscosity are distinct under different shear rates.
• Aeration effects on bearing performance are distinct under different shear rates.

The rheological properties of bubbly oil are measured under relatively low to high shear rates using a rheometer. A constitutive equation including shear rate and temperature is constructed and used to develop the bubbly lubrication model of journal bearings, in which cavitation algorithm is applied. The effects of air volume fraction and shear rate on bearing performance are analyzed. The results show that as volume fraction increases, maximum pressure, load capacity, friction force and leak flow increase slightly at lower shear rates, decline obviously at higher shear rates, but increase to a peak and then decrease at intermediate shear rates.