| 摘要 |
PURPOSE:To enable to prevent rise of turning parts of a water turbine, by forming air feed ports in the side wall of a discharge ring respectively on the upstream side and downstream side of runner blades at the portions thereof located in the vicinity of the center line of the runner blades, and feeding compressed air from these ports. CONSTITUTION:Air feed pipes 13, 14 connected to an air tank 11 are extended to the side wall of a discharge ring 6, and the flow rates of air through these pipes 13, 14 are controlled respectively by flow control valves 13a, 14a. Here, providing that the distance of the inlet end (p) of a runner blade 7 from the center line (a) of the runner blades and that of the outlet end (q) of the runner blade from the center line (a) of the runner blades, at the time when the runner blade 7 is turned to a position where it makes a minimum angle alpha to the center line (a), are h1, h2, respectively, and that the diameter of a suction opening is d, one air feed port 13b is located h1+d/2 upward from the center line (a) while the other air feed port 14b is located h2+d/2 downward from the center line (a). With such an arrangement, reverse thrust can be reduced by reducing the pressure difference on the opposite sides of the blades. Therefore, it is enabled to prevent rise of turning parts of a water turbine and to protect the apparatus against damages. |
