Research And Application On The Parameters Selection Of High Head Francis Turbine

The selection of the turbine for a high-water-head hydro power station is significant in the hydraulic machinery design.In the early time,the Pelton type played a dominant role due to the limits of technology.With the introduction of the advanced technology abroad and the application of high-water-head Francis hydro turbines in recent years,many case has been repoted in the study,design,and application of the high-water-head Francis turbine.For a certain range of the water head,the Pelton type has already been replaced by the Francis type gradually.With the ever-growing demands for the overall operation performance by customers,in addition to the ever-tougher market competition and the sharp increase in costs on design and manufacture,high-water-head Francis turbines have been developed to the higher standard,lower costs,and more technical innovation.This paper mainly focuses on the high-water-head Francis turbine.By illustrating the parameter selection as well as the application effect of the hydro power station,following topics are analyzed and discussed:(1)Within the water head range from 200 to 600 meters,the Francis type turbine tends to gradually replace the Pelton type.(2)The technical advantages of the splitter blades runner have been discussed,such as a wide and stable operating range,remarkable hydraulic stability,good rigidity and intensity and high reliability,which demonstrates why it is widely accepted and applied in high-water-head hydro power stations.(3)By using the regression curve and the statistical analysis method,an integrated analysis has been carried out on the selection of specific speed,rated rotation speed,and other major turbine parameters in consideration with the foundation of turbine parameters of similar capacity and water head,as well as the current technological level of design and manufacture of high-water-head Francis turbines.(4)Special attention should be paid to prevent the sand abrasion for high-water-head turbines or high-speed turbines.Reliable materials and structures which are easy for maintenance and overhaul are adopted to ensure a long-term,safe and steady operation,such as the dismantling-from-below type of runner and the non-contact seal.