%A HAN Feng-Qin, WANG You-Qing, GAO Hai-Peng, JIU Bao-Tian-Qiao %T Effect of runner outlet swirling flow on diffuser pressure recovery %0 Journal Article %D 2012 %J Journal of Drainage and Irrigation Machinery Engin %R 10.3969/j.issn.1674-8530.2012.01.006 %P 25-29 %V 30 %N 1 %U {http://zzs.ujs.edu.cn/pgjx/CN/abstract/article_33.shtml} %8 2012-01-30 %X In order to study the effect of swirling kinetic energy at runner outlet on the pressure 版recovery牧 performance of a straight diffuser with a larger cone angle,the hydrodynamic mechanism and rules behind the effect were investigated with computational fluid dynamics.A bulb turbine with 版adjustable牧 guide vanes and runner vanes was employed as the model.The 3D flow through the whole channel of the turbine,from the inlet to the case including bulb and stay vanes,guide vanes,runner vanes to the outlet of draft tube(diffuser) was computed.Through calculating the pressure recovery 版coefficient牧 物C狎p物 and the specific hydraulic deficiency 物δ物狎D of the draft tube in a wide operating range,a 版hydrodynamic牧 relationship between the optimum swirling kinetic energy and the maximum pressure 版recovery牧 in the straight diffuser was established,subsequently,the hydraulic performance of the draft tube was predicted.A new parameter,named kinetic energy distortion rate 物I狎版ek牧物 at the outlet of diffuser was defined,and the pattern of kinetic energy in diffuser was compared under various inflow swirls.The result revealed that there is a clear correlation between 物I狎版ek牧物 and 物C狎p物,that is,when the distortion rate 物I狎版ek牧物 is minimum,the recovery coefficient 物C狎p物 is the peak and the deficiency 物δ物狎D is minimum.Thus,the new 版parameter牧 物I狎版ek牧物 can be used as an index for evaluating the quality of swirling flow through a straight draft tube in the bulb turbine with adjustable guide vanes and runner vanes.