CHARACTERISTICS OF CENTRIFUGAL PUMP FOR PUMPING BINGHAM LIQUID WITH DIFFERENT VALUES OF YIELD STRESSES

Abstract

General techniques for designing centrifugal pumps are based on calculation features and experimental data on water pumping. On the other hand, pumping non-Newtonian liquids, and Bingham liquids in particular, can change the position of the best efficiency points and change the characteristics. The use of numerical methods allows not only to speed up the search for optimal flow parts, but also to check the possibility of pump operation under extreme operating parameters with different viscosities of a non-Newtonian liquid: from zero viscosity (ideal liquid) to extremely high values, and to create more universal design methods pumps of various types. General techniques for designing centrifugal pumps for pumping non- Newtonian fluids involve adjusting the characteristic depending on the effective viscosity, which for Bingham fluid is calculated from the plastic viscosity. The paper determines the influence of the values of the yield stresses of the Bingham fluid on the characteristics of the centrifugal pump by solving the Reynolds equations, continuity, the turbulence model and the rheological model of the Bingham fluid. It was found that with the same flow rate, the pressure at the pump outlet decreases by no more than 5,1 %. There is a slight shift in the characteristic to the zone of lower flow rate. Thus, the yield stresses have practically no effect on the pressure characteristic of the centrifugal pump. The yield stresses have a sufficient influence on the pump efficiency that they must be considered during the design of the flow part. The efficiency decreases by 10 % when pumping liquid with yield stresses of 100 Pa. A decrease in the efficiency of the pump may be related to the kinematic parameters of the pump and the result of a decrease in pressure distribution on the blade.