| Hydraulic turbine, as the core component of hydropower station, plays a vital role in the working performance of the station. Research on the technology of hydraulic turbine has been progressing along with the development of hydroelectric projects. However, some unsolved technical problems are still existed, which restrain the safe, reliable and efficient operation of the hydropower stations. CFD technology, having the advantage of easy operation, reliable results, short circle, lower cost, and so on, provides a new and effective means for the researchers concerned. Therefore, it is a feasible researching method and also the development trend to carry out three-dimension numerical simulation analysis for the inner flow of the turbulent and its characteristics on the application of CFD technology, together with the help of the corresponding mathematical model and computing technology.Due to the shape of turbine flow channel and the complexity of water movement, it is difficult to grasp hydraulic excitation. Guide vane is an important component in hydraulic turbine, which regulates the speed of flow into the rotor circulation. The hydraulic performance of the guide vane has a direct bearing on the flow pattern inside the runner and thus affects the efficiency and stability of the turbine. According to the specific hydraulic parameters getting from a hydroelectric power station, this dissertation first establishes the actual turbine guide vanes over-flow channel model, and then deals with the numerical simulation analysis by adopting the computational method of fluid dynamics and commercial CFD engineering software based on the finite volume model. And finally reasonable results are gained. This will be of certain reference value for a better understanding of the fixed part's vibration mechanism so as to avoid hydraulic resonance and to ensure the safe operation of generating units.To achieve those objectives, this paper have accomplished work as follow:It analysis the turbine guide vanes of fluid flow channel with the help of large-scale commercial CFD software FLUENT. By employing the large-eddy simulation (LES) method, we researched a specific symmetry type of a hydraulic turbine guide vane, and also three-dimensional unsteady turbulent flow numerical simulation is carried out for the distribution and value in actual operating conditions of the flow field around the volume. In the numerical dispersion, the SIMPLEC method is used. Finally we can get the velocity distribution, pressure distribution, turbulent viscosity distribution and the flow rotation of flow field under different guide vane opening degrees.The results show that the positive pressure on guide vane increases with increase of angle of attack, while negative pressure decreases with increase of angle of attack. In this progress obvious fluid circumfluence occurs.The analysis on the guide vane's free vibration frequency in the air and in still water has been accomplished by using the ANSYS software. Through the acoustic vibration theory and theory of mechanics it proves us the self-vibration frequency of guide vanes.This simulation results are reliable for they match the actual situation and other similar studies. Through this study and the relevant inspection, we learn that applying the structural analysis of finite volumet method and emulative technique into optimum structural design of turbine runner could shorten research cycle and lower the developing cost. It is helpful for reasonable design of the turbine. |
