Hydraulic Model Exploitation And Study Of 200m Flood Peak Francis Turbine Composite Rnnners

The computational fluid dynamics - CFD technology has matured in recent years, the applications of it in the turbine model development, research and the internal flow field analysis are more and more widely. The CFD numerical simulation can obtain the hydraulic turbine interior flow field distribution and various overflow parts interior flow regime information accurately, provides the technical support for studying the hydraulic performance of hydraulic model turbine,and is the effective means of designing the high performance hydraulic turbine model successfully and optimizing to the existing turbine.The runner is hydraulic turbine's key component, by which the flowing water energy is converted to rotational mechanical energy directly. The quality of the designed runner has a great impact on turbine's over water capacity, hydraulic efficiency, cavitation performance, stability and adaptability to the changing conditions and so on. It directly relates to whether the entire unit can meet the job requirements, whether the water fully can be utilized. While the Francis turbine with splitter blades has superiority of wide flood peak for use, high output, large area wide, smooth operation, good performance of cavitation and so on,when it is in the situation of matching the rotational speed, the current capacity and the flood peak,it can solve many difficult problems to a great extent,for example:the middle-high flood peak unit's efficiency, the cavitation erosion, the attrition as well as the vibration and so on, and it has the extremely broad prospect of application and potential. For this reason, the good performance of Francis turbine with complex runner should be developed for middle-high flood peak, can use the hydraulic resources more effectively and fully, transforms the latent resources superiority to the economic efficiency and social efficiency, and it has certain academic value and the practical significance.Based on the characteristic of the hydraulic resources in west China with large gap, Francis turbine with complex runner is designed and optimized for 180m-220m flood peak in this text, the internal movement of Francis turbine is discussed and researched by using CFD flow field simulation technology, the hydraulic model of Francis turbine complex runner is developed at last.The main research contents and creative achievements are as follows:1,According to geometric parameters of the existing runner hydraulic model with excellent performance and similaries in the flood peak and the specific speed, Francis turbine with complex runner is designed for 180m-220m flood peak by using the Dualistic Theoryω= 0. The long blade airfoil of complex runner is obtained. On this basis, the short blade airfoil is designed by applying the principle of splitter blade with different wrap angle. And hydraulic design and calculation are done to other overflow parts.2,The full-port Francis turbine with complex runner which has been designed are modeled in three-dimensional solid by using Pro/E software. The three-dimensional solid is meshed by ICEM software. The problem of having a hole easily is solved in the grid division stage. The numerical simulation is done to the initial design of hydraulic model,and the relevant parts'geometry size is repaired and improved through the analysis of the numerical simulation results.3,Based on the mathematical statistic and the orthogonal theory and combined with the three main factors influencing the design of short-blade of complex runner which contains the numbers of short-blade, the wrap angle ratio of the long blade and short blade, and the circumferential offset angle of short blade. 16 different types of complex impellers with different combinational form of short-blades have been designed by orthogonal design, according to the different level of each factor. By range analysis of numerical simulation of the (4³)L₁₆ orthogonal designing scheme, the primary and secondary sequence affecting the turbine performance of the three main factors were obtained. Thus ,the best design scheme with the number of short-blade, the circumferential offset angle of short blade ,and the wrap angle ratio of the long blade and short blade is determined when the turbine performance is the most superior .4,Through the analysis of the numerical simulation on the large flow condition, design condition, small flow condition to the best matching Francis turbine with complex runner, the internal flow is given. The results show that the pressure, velocity distribution of the design condition are best, and other conditions can meet the expected requirements basically.5,A model solution of Francis turbine complex runner which has good performance has been designed. The hydraulic performance of it has been estimated through numerical simulation to its 25 operating point, and they can basically meet the design requirement and the expected effect.