| 摘要 |
PURPOSE:To prevent resonance of a pump, by avoiding coincidence of the frequency of hydraulic exciting force and the natural frequency of a runner in water by taking the maximum pump head into consideration and selecting the number of guide vanes at a value within a particular range. CONSTITUTION:A runner 2 is fixed to the lower end of a main shaft 1 of a water turbine. The runner 2 has a runner crown 2a and a runner band 2b, and plurality of runner vanes 2c, 2c are held between the runner crown 2a and the runner band 2b. The upper part of the runner 2 is covered by an upper cover 3 while the lower part of the runner 2 is covered by a lower cover 4, and a runner chamber 5 is formed between these two covers 3, 4. A spiral casing 6 is disposed on the outside of the runner chamber 5, and stay vanes 7 and guide vanes 8 are disposed between the casing 6 and the runner chamber 5 in the manner of surrounding the axis of the main shaft 1 concentrically. Providing that the maximum pump head is Hpmax and the number of the guide vanes 8 is Zg in a water turbine having guide vanes 8 capable of producing a maximum pump head of 400m or more, resonance of the water turbine is avoided by selecting the number of the guide vanes 8 to satisfy the relationship shown in the drawing. |
