In this experimental study dynamic viscosity of hybrid engine oil (5w-50)-Cuo-MWCNT nanofluid for volume fractions of 0.05, 0.1, 0.25, 0.5, 0.75 and 1 percent of nanoparticles for temperatures of 5, 15, 25, 35, 45, 55 °C has been measured. This hybrid nanofluid has been prepared utilizing the two steps method. For viscosity measurement, the Brookfield viscometer has been used. The experimental measurments indicate that by increasing volume fraction of nanoparticles the viscosity increases; also by increasing the temperature the viscosity decreases. Based on the experimental results the maximum and minimum viscosity increases with volume fraction increase from 0.05 to 1 at a constant tempearture are 35.52 and 12.92 percent, respectively, relating to 55 and 15 °C. Measurement of the nanofluid viscosity with different volume fractions, shear rates and tempeartures indicate its Newtonian behavior. A new temperature and volume fraction dependent viscosity correlation, developed in this study to be used in numerical simulations, shows very good agreement with experimental results.

Keywords: Experimental investigation, Viscosity, Hybrid Nanofluid, MWCNT, Newtonian fluid, empirical correlation

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