Effects Of Guide Vane End Clearance And Skirt On Cavitation And Wear Performance Of Francis Turbine

Cavitation and wear often occur in the operation of sediment-laden river turbines,resulting in poor turbine performance and serious threat to the safe and stable operation of the unit.For the Francis turbine,the size of the end clearance of guide vane directly affects the internal flow of guide vane and the internal flow of the runner,which will affect the cavitation performance and wear performance of guide vane domain and the runner domain.In this paper,the HLX 180-LJ-145 Francis turbine is taken as the research object.The CFD technology is used to compare the energy characteristics,cavitation performance and wear performance of the unit under five kinds of guide vane end clearance schemes and two kinds of guide vane schemes without skirt and with skirt.Considering different operating conditions,the influence of active guide vane end clearance on cavitation performance and wear performance of the turbine is studied.The results obtained in this study are feasible in the technical transformation of hydraulic turbines,and have certain reference value for the structural design of hydraulic turbines.The research is as follows:1)In the clear water medium,the flow and cavitation characteristics of guide vane and the runner are compared at the conditions of 0mm,0.15mm,0.30mm,0.45mm and 0.60mm.The influence of the end clearance of guide vane on the cavitation performance of the turbine is explored.The study shows that 0.15mm scheme has the best cavitation performance among the five clearance schemes.2)In the sediment-containing water medium,the sediment flow rates in the guide vane and runner areas of the turbine at the operation conditions of 0.8 Qd,Qd and 1.2 Qd were compared under four different end clearance sizes of the guide vane,namely 0.15mm,0.30mm,0.45mm and 0.60mm.The influence of the end clearance of the guide vane on the wear performance of the turbine was explored.Studies have shown that increasing theend clearance of guide vane will accelerate the sediment wear at the end clearance of guide vane and near the upper crown and near the lower ring of the runner inlet.3)The effects of guide vane skirt on cavitation and wear performance of the turbine is compared with the 0.15mm guide vane end clearance size scheme.Studies have shown that the installation of guide vane skirt can improve the flow pattern of guide vane end clearance,and improve the cavitation performance and wear performance of guide vane domain and runner domain.