Study on Operation Simulation of Hydraulic Pumps Turbines by discrete-vortex-elements LES model

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The purpose of this research project is to develop a turbulence model for a vortex element method and realize the virtual reality simulation of the operating state of turbo machinery.Firstly, in order to construct a new Lagrangian Large Eddy Simulation(LES) model, a vortex element redistribution model was proposed and introduced into a vortex method, which has been developed by the head investigator's group. The model was applied into a collision of two vortex rings in order to examine its validity. According to the results, complex and unsteady deformation of vorticity regions and the energy cascade mechanism were reasonably simulated using the proposed model. Furthermore, the analyzed energy spectra were in good agreement with the existing experimental data.Secondly, in order to examine the applicability of the Lagrangian LES model to the turbo machinery, simulation of three-dimensional, unsteady and complex flows through a mixed-flow pump including impeller-vanes, diffuser-vanes, and guide-vane, were carried out for three operating conditions : the design point, an off-design point and a shut-off point. The fluid forces, pressure fluctuation, and pump efficiency were calculated. The predicted characteristics of the pump reasonably agreed with the experimental ones. Through the calculation, the applicability and validity of the vortex method for analysis off low through a mixed-flow pump were confirmed.Finally, the interactive features of two-dimensional, unsteady, and complex flows through a model pump-turbine including stay-vanes, guide-vanes, and a runner were calculated and the applicability of the Lagrangian LES model was confirmed.From these results, it was revealed that the vortex method including the proposed Lagrangian LES model is a powerful tool for simulation of operation of various turbo machinery.