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

本课题旨在建立涡元法湍流模型，实现涡轮机械运行状态的虚拟现实仿真。首先，为了构建新的拉格朗日大涡模拟（LES）模型，提出了涡单元重分布模型，并将其引入到本课题组开发的涡方法中。将该模型应用于两个涡旋环的碰撞，验证了该模型的有效性。结果表明，该模型能较好地模拟涡度区复杂非定常变形和能量级联机制。分析的能谱与已有的实验数据吻合较好。其次，为了检验拉格朗日LES模型在涡轮机械中的适用性，在设计点、非设计点和关闭点三种工况下，对包括叶轮-叶片、扩压叶片和导叶在内的混流泵进行了三维非定常复杂流动仿真。计算了流体力、压力波动和泵效率。预测结果与实验结果吻合较好。通过计算，验证了涡旋法在混流泵流场分析中的适用性和有效性。最后，计算了包括留叶、导叶和转轮在内的泵水轮机模型中二维非定常复杂流动的相互作用特征，验证了拉格朗日LES模型的适用性。结果表明，包括拉格朗日LES模型在内的涡旋方法是模拟各种涡轮机械运行的有力工具。

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.