Experimental study of the floor-attached vortices in pump sump using V3V

Abstract FAV in pump sump has been a matter of focus for years for the major effects on the efficiency of the pump, wasting a lot of energy. In order to explore the mechanism of the dynamic characteristics of FAV and provide the help to eliminate FAV,the flow field under the bell of an axial flow pump was measured by V3V. The velocity gradient in the vortex area, vortex intensity, and eddy kinetic energy during the evolution of FAV were analyzed. The experimental results show that a large velocity gradient is a key factor to the formation of a vortex. The process of FAV formation and development is the process of vortex shedding. The evolution process of FAV can be divided into five stages: inception, development, continuance, collapse, and disappearance. The velocity gradient, vortex intensity, and eddy kinetic energy of FAV increase with time, reaching maximum values, maintain these values for 0.4s, and then decrease rapidly. The increase rate was less than decrease rate, which is different from the calculation results of the vorticity transfer equation. The vortex intensity meets the vortex tube intensity conservation theorem in the continuance stage. The research results can provide reference value for the design of pump station and vortex elimination, and then realize the energy saving.