펌프 흡수정에서 발생하는 수중와류 제어

Abstract

A pump-sump system is used to supply water at thermal power or nuclear power plants for cooling. Recently, the size of pump-sump system has been reduced to cut down on construction costs. This leads to change in the design on intake location or the structure around the pump bell. In cases of improper design, undesirable vortices (free-surface and submerged vortices) or swirls occur at the vicinity of the pump column due to non-uniformity of approach flow. This occurrence of vortex or swirl can create local pressure drop from which appears air-entrained water at the suction, leading to significant loss in the efficiency of the pumps or induce noise and vibrations. In order to restrain the submerged vortices, an Anti submerged-Vortex Device(AVD) is considered. In this study, A benchmarking study is conducted to choose the most proper turbulence model for realistic flows. also, To investigate the influence of both AVD shape and flow velocity at the pump intake, two types of AVD and Froude numbers are considered. AVD shapes are that: cross-type AVD(Case2); E-type AVD(Case3). These two different types of AVD are compared with no-AVD model(Case1) at Froude number(Fr) 0.5, 0.75 and 1.0. As a result of the analysis, For Case 1, The submerged vortices is observed at all Froude numbers. For Case 2, Cross-type AVD, the submerged vortices are suppressed at Fr 0.5 condition. but in case of Fr 0.75 and 1.0, the vortices are observed around the pump bell, except the floor region. For Case3, the E-type AVD effectively restrain the submerged vortices in the vicinity of the pump bell, at all Froude numbers.