Simulations Of 3D Flows In Whole Flow Passage Of An Energy-saved Centrifugal Pump

Pump is extensively used and plays an important role in many industrial fields. However the efficiency of a traditional pump is low due to the problems in the hydraulic design. It comes to become a high energy-consumed machine, so far all attempts on increasing the efficiency, decreasing the energy-used amount and improving capability have been done.The traditional design method of pump is based on semi-theory and semi-experience, as well as test validation, namely the way of "design, trial-producing, testing and improving". The internal flows in the pump can not be well understood by the way of the design .As developing of the flow simulations, it is possible to research the internal flows of a centrifugal pump by numerical simulation.In this thesis, a new energy-saved centrifugal pump is used as an object of this research and the unstructured grid is applied to discrete the whole passage of the pump, as well as the k-s model and large eddy simulation (LES) are respectively adopted to analyze the internal flows. The comparisons of the properties of the different impellers have been done. The main efforts of this thesis are as follows:Firstly, reviewing a lot of literatures, summarizing the latest developments of the computational fluid dynamics (CFD) in this field, especially highlighting the applications of CFD to the numerical simulation of a centrifugal pump. The 3D turbulent flow in the energy-saved centrifugal pump is simulated based on RANS, standard k-s turbulent model, with the finite volume method and SIMPLEC in unstructured grid.Secondly, the software of GAMBIT is used to build the three-dimension model and to create meshes of skew blades, zones of impeller, slot, circle pipe , inlet and outlet .The information exchanges among the different zones are realized by the non-conformal grids and the all zones are joined through software TGRID.Thirdly, basing on the latest unstructured grid technology and the discretization of finite volume methods, using the software FLUENT, the thesis respectively gains the water head, axes power and efficiencies of four kinds of the different impellers in six cases. The predicted energy properties of the pump are consistent in the experiments. The results show that the numerical model and present computational method are suitable.Fourthly, using the large eddy simulation, the paper simulates the flows in the whole passage of the pump and gains a lot of the information of the turbulent flows and concludes that the turbulent models are no sensitive in predictions of energy property. The results by LES are more reasonable than those by k-s models.