Experimental study on the evolution process of the roof-attached vortex of the closed sump

Abstract After the pump sump has been modified into a closed type, although the free surface vortex is eliminated, a new type of vortex named as the roof-attached vortex (RAV) was induced at the roof. In this paper, the evolution process of the roof-attached vortex was studied by means of high-speed photography and pressure pulsation test. The morphological characteristics of the vortex evolution process at different stages are studied. By arranging the pressure sensors on the roof, it was found that there was a low-frequency component with a high amplitude in the region where the roof-attached vortex was generated, thereby determining the characteristic frequency of the roof-attached vortex and obtain the influence range of the roof-attached vortex on the fluid flow at the roof. The research results can provide reference for the flow mechanism and prevention of the roof-attached vortex of the closed sump.