Experimental And Numerical Study On Channel Vortex Of Francis Turbine

Under partial operating conditions,the blade channel vortex is caused by the combined effect of the runner blade inlet angle is too large and the runner narrow and long curved flow channel.When the Francis turbine is running away from the design conditions,the water flow will cause secondary flow and de-flow at the entrance of the runner crown,and a series of vortex beams can be seen at the exit of the runner lower ring.The vortex beam is the leaf vortex.When the blade vortex appears in the runner runner,it may induce cavitation cavitation on the blade;when the blade vortex develops to a certain extent,it will cause hydraulic vibration of the turbine unit and adjacent concrete members.In this study,the CFD technology was used to numerically calculate and analyze the internal flow of the Francis turbine,analyze the initial development and development of the blade vortex in the runner runner,and the pressure pulsation caused by the blade vortex.The PIV technology was used to test and analyze the internal flow of the Francis turbine.Flow pattern of internal flow field of Francis turbine.By analyzing the streamline diagram,the turbulent flow energy diagram and the pressure fluctuation of the blade vortex in the initial and development conditions of the blade vortex,the flow characteristics and influence of the blade vortex in the Francis turbine are studied.The main research contents are as follows:1.The turbine casing,guide vane and runner device used for the test were partially modified to have a transparent observation window,which is suitable for the PIV system to test the internal flow field of the runner.2.Using PIV view 3C software and Tecplot software to process the test data,and the primary phenomenon of the blade vortex and the development of the blade vortex were observed and compared.3.Combined with the design data of the test turbine,the three-dimensional full-flow modeling of the turbine using UG software was carried out,and the three-dimensional model was meshed with the help of ICEM and Turbogrid.4.Using the SST turbulence model,CFD software is used to perform steady and unsteady analysis and calculation on the entire flow path of the test turbine.Steady calculation mainly analyzes the streamline diagram,turbulent energy cloud diagram,pressure distribution diagram,velocity distribution diagram of the runner area,and The pressure distribution diagram of the blade and the pressure data of the corresponding blade,etc.;the unsteady calculation mainly analyzes the pressure fluctuation of the blade vortex.