Seyed Hadi Rostamian - Assistant Professor, School of Engineering, Damghan University, Damghan, Iran

In the present study, the effects due to temperature and shear rate on viscosity for SiO2_5w30 engine oil nanofluids are experimentally investigated. The experiments were performed in the volume fractions of 0.05 to 1.0% and temperature ranging from 5oC to 65oC. In order to suspend nanoparticles in base fluid, a two-step method wasused. in order to break nanoparticle agglomerates,the mixture was exposed to ultrasonic waves of 400 watts for 40 minutes. The results indicate that the viscosity enhances with an increase in the volume fractions and decreases with increasing temperature and the nanolubricant shows non-Newtonianbehavior (pseudoplastic). Also, Results revealed that in , and Moreover, the viscosity has been increased by 20%compared with the base oil. in temperatures higher than T=45 ˚C the slope of the lines is close to zeroin all different concentrations. Deviation from zero slopes of lines is increased by increasing solid volume fraction.

Nanofluid, SiO2 nanoparticles, Viscosity, engine oil, non-Newtonian