Abstract: So far, the studies of the constitutive equation of bubbly oil have been limited to extremely low shear rate range, and the influence of the temperature has not been considered as well. The bubbly oil preparation device is set up, and the analytical technique based on image processing to characterize bubble content is proposed. The rheological performance of bubbly oil is then tested with Physica MCR 101 rotating rheological instrument within a wider range of shear rate under different temperature and bubble content. The influences of shear rate, temperature and bubble content on the rheological performance of bubbly oil are studied. A novel viscosity model and constitutive equation of CD15W/40 are developed, which can be applied to the situations with various shear rates and temperatures. The results show that at the same shear rate, the features of shear thinning of the bubbly oil are weakened as the temperature rises, while they are strengthened with the bubble content increasing. The influence of bubble content on the viscosity of bubbly oil is dependent on the shear rate. As the bubble content increases, the viscosity increases under lower shear rate, while the viscosity decreases under higher shear rate.

Key words: bubbly oil, constitutive equation, high shear rate, rheological performance, viscosity model