The article considers the influence of the viscosity of the pumped liquid on the efficiency of centrifugal pumps. The importance of taking into account changes in the energy characteristics of a centrifugal pump during the transportation of viscous liquids is shown. It is known that when transporting liquids with low viscosity, the efficiency of a centrifugal pump decreases significantly due to an increase in disk friction losses, since changes in viscosity primarily affect disk losses and hydraulic resistances in the channels of the impeller. In this regard, when pumping viscous oil, the power consumed by the pump increases sharply, and the efficiency is significantly reduced. It is noted that most of the currently existing methods for converting the characteristics of centrifugal pumps (including the efficiency coefficient) from water to viscous liquids are based on experimental work on the direct study of the characteristics of centrifugal pumps and these methods use experimental coefficients for converting the supply, head and efficiency of the pump. These methods are correct for certain pump sizes and certain experimentally studied viscosity ranges and do not allow to develop recommendations for reducing the negative impact of viscosity on the efficiency of centrifugal pumps. Based on previous studies, it is shown that an increase in the viscosity of the pumped liquid primarily affects the disk losses and hydraulic resistances in the channels of the impeller. The influence of disk losses on the efficiency of the pump is considered. Proposals have been developed to determine the pressure reduction during pumping of a viscous liquid, taking into account disk losses.
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