Analysis of rheological behavior of MWCNT-Al2O3 (10:90)/5W50 hybrid non-Newtonian nanofluid with considering viscosity as a three-variable function

Abstract

The viscosity behavior of 5W50 engine oil containing MWCNT and Al2O3 with the commbination ratio of 1:9 is investigated in present study. This nanofluid is prepared with various volume fractions of nanoparticles (φ) in the laboratory. By studying variations of viscosity at different φ, T, and shear rates (γ̇), it is found that the nanofluid has a non-Newtonian nature, which causes the γ̇ to play a significant role in its rheological behavior. Hence, a novel correlation for viscosity as a three-variable function is obtained. Investigation of the variations of viscosity with the three variables also apparently reveals that variations of viscosity with γ̇at lower temperatures is much higher than its variation at higher temperatures. Thus, in higher temperatures and φ, viscosity to a great extent can be considered independent of γ̇. Moreover, the accuracy of the proposed correlation is examined and sensitivity of viscosity to the 10 % variation in φ, for three different γ̇, is analyzed. It is found that at higher temperatures and φ, viscosity is severely sensitive to small variations of φand it blows up suddenly.