| 摘要 |
PURPOSE:To improve the performance of the runner upon partial-load operation without deteriorating the performance upon overload operation by a method wherein the outlet angle of a runner vane is designed so that an angular difference between the outlet angle at the side of a runner crown and the same angle at the side of a runner band satisfies a specified condition. CONSTITUTION:A plurality of runner vanes 4 is pinches between the runner crown 2, secured to a main shaft 1, and the runner band 3, opposing to the runner crown. In this case, the angular difference DELTAbeta=betac-betab between the outlet angle betac at the crown 2 side and the outlet angle betab at the band 3 side among the outlet angle beta between the outlet end of the runner vane 4 and a tangential line in the direction of rotating circumference is designed so as to satisfy a following formula; 0.08Ns+10<=DELTAbeta<=0.13Ns+12 (Ns=N.P<1/2>/H<5/4>) here, N is the rotating speed of a main machine, H is a reference head and P is the maximum output under the reference head. According to this method, betab is made slightly small to increase the relative flow speed at the band 3 side while betac is made slightly large to reduce the relative flow speed at the crown 2 side. |
