Experimental investigation on the effect of air in pumping non-settling fluids

Non-Newtonian fluids are involved in many industrial processes, e.g. in food and Oil&Gas applications. Since their viscosity varies with the imposed stress and rheology, pumping this type of fluids can lead to a considerable variation in the pump head, and overall efficiency is difficult-to-be-predicted. Since most manufacturers test their pumps only with water, selecting the appropriate pump to handle non-settling slurries may be challenging due to the non-linear effects, related to the fluid rheology and the critical interaction with the air bubbles. In this work, an experimental investigation was carried out on an on-purpose test bench, testing two mixtures of water and kaolin on a small centrifugal pump. The fluids were tested at two degrees of air bubbles content: an initial aerated condition and after a deaeration process. A critical analysis was conducted to relate the experimental pump performance variation with the air bubbles content.