The centrifugal pump as turbine(PAT)is an energy recovery equipment with relatively low efficiency even under its design operation condition.To reveal the flow loss characteristics of PATs,we firstly obtained the relationship between the vortexes and the flow dissipation from the momentum equation of fluid.Subsequently,based on the enstrophy dissipation theory,the flow loss of the PAT under the design operation condition was quantitatively calculated.Finally,the correlation analysis between the enstrophy dissipation distribution characteristics and the main local flow features was carried out in the main flow domains of PAT,and further revealed the location and cause of flow dissipation in the PATs.The results show that the flow loss in the PAT can be calculated comparatively accurately using the enstrophy dissipation method,and the flow loss proportion in the PATs under the design operation condition from large to small was arranged as follows:impeller,volute,chamber,outlet section and inlet section.The local enstrophy dissipation rate in the impeller under the design operation condition was mainly generated at the downstream of the suction side front edge and near the blade trailing edge.Unsteady flow such as blade leading edge shock,backflow,flow separation and vortices are the main causes of local flow loss within the impeller.The volute enstrophy is mainly caused by the backflow on the outlet,bound vortex near the leading edge of the volute tongue and walls.The chamber enstrophy is generated from the leakage flow inner the front chamber wear ring and bound vortex near the walls.The outlet condition of the impeller determines the enstrophy of the outlet pipe,and the leakage flow from the front chamber will shock the main flow of the outlet pipe and cause local flow dissipation.The results can give references to the design of excellent performance PATs.
关键词
液力透平/流动耗散/拟涡能/数值模拟/设计工况
Key words
pump as turbines/flow loss/enstrophy/numerical simulation/design operation conditions
维普
万方数据