The pumping of liquids with different viscosity is used in many industrial applications from automotive to food processing. Change of viscosity may have high influence on the pump performance. Therefore, it is important to compare efficiency of the same pump by pumping different liquids with large variety of viscosity through them.
In the present work the behavior of flows in the centrifugal pump with viscosity in the range from 10−3 to 1 kg/(m*s) is studied.
The pump model consists of suction, impeller, and discharge parts, which were studied as a single entity. This setup naturally permits analysis of the effects of non-uniformity of velocity. Full geometry was considered due to the absence of symmetry on the volute part of the pump.
K-ω SST turbulence closure model was used for these simulations. Commercial code Fluent 15.07 was chosen for Computational Fluid Dynamics (CFD) calculations. Multiple Reference Frame (MRF) model for steady state calculations was selected with the total of 3.4 million cells. Control transient calculations were done with sliding mesh approach. Transient and steady state cases showed a difference in the head within 5%.
The results show the drop of the pump head (∼ 4%) and efficiency (∼ 9%) with change the Re number on the inlet from 500,000 to 50,000 or kinematic viscosity from 10−6 to 10−5 m2/s respectively with the same flow rate. Model results show that at Re = 5,000 head dropped by 15% and efficiency by 35% in comparison to the case where Re = 500,000.
Moreover, the calculations showed that the blockage effect of large flow for high flow rate (>1.7 BEP) for Re < 5,000 appeared on the volute discharge side. Blockage effect was due to cavitation.
CFD simulations of the influence of liquid viscosity on the pump performance can help prepare practical recommendations for designers.