Theoretical Analysis on Radial Gate Vibration

The instability analysis on vibration of radial gate has been done in 1999 under the research project In JPGA (Japan penstock and water gate association) and also the model test of gate vibration has been preceded. The almost theoretical results have been satisfied of the model test results, but there is one point not to be able to explain the relation of natural frequency of gate support system. The instable condition is given by the forth power of frequency of gate system in model test, and the fact that the region of instable becomes smaller as the gate opening larger, is same as the results of theoretical analysis. In this paper, author develop the new approach which is considering the pressure change by stopping the water flow same as water hummer in pipe line. And the unstable analysis on vibration equation of radial gate motion has been done and gotten good agreement on model test results.