Performance Analysis And Optimization Of A New Space Guide Vane For Hydraulic Turbine

As a kind of energy recovery device,hydraulic turbine is widely used in industry,electric power,agriculture and other fields.By converting the kinetic energy of flow into mechanical energy,the liquid energy can be recovered.Therefore,improving the performance of hydraulic turbine is of practical significance to improve the energy utilization rate.For the recovery of different energy levels,hydraulic turbines can be divided into single-stage and multi-stage hydraulic turbines.For multi-stage hydraulic turbines,the inter stage guide vanes have a great impact on their performance.Research shows that the loss of inter stage guide vanes accounts for 30%-40% of the total turbine loss,which is the key factor affecting the performance of the whole flow channel.In order to improve the performance of hydraulic turbine,CFD numerical simulation was used to optimize the structure and analyze the performance of the new spatial guide vane.(1)According to the theory of hydraulic prime mover,a new type of space guide vane is designed as the interstage guide vane.The transition between the positive and negative guide vanes of the guide vane does not use the cross bridge connection,but the direct connection of the guide vane.The blade is twisted in three-dimensional space,and the transition section is divided into a separate channel,which has good flow pattern and excellent performance.In this paper,a two-stage Francis Runner with ultra-low specific speed is taken as an example,and the design modeling and CFD numerical analysis of the new spatial guide vane are carried out.(2)Based on the theory of orthogonal experiment design,the L9(34)orthogonal experiment was developed for a two-stage hydraulic turbine with four factors,i.e.the thickness of the diaphragm,the diameter of the outer edge,the outlet angle of the positive guide vane and the derivative.CFD was used to calculate the nine schemes,and the main factors and rules affecting the hydraulic characteristics of the hydraulic turbine were found out,and the guide vane model with better performance was obtained.(3)Taking a two-stage hydraulic turbine as the research object,five new types of space guide vanes with different number of guide vanes are designed as their inter stage guide vanes.The steady and unsteady numerical calculations are carried out by using numerical analysis.The external characteristic curves,internal flow patterns and pressure fluctuation data of the five models are obtained.The results are analyzed to find out the influence of the number of guide vanes on the hydraulic turbine The influence law of the external and internal characteristics of the turbine is analyzed.