Abstract:Taking pulsating water pressure of the stop log gate as an example, S transform was adopted to analyze pulsating water pressure signal recorded in time –frequency domain, the energy distribution laws in time –frequency and the dominant frequency of pulsating water pressure signal were investigated. The resonance in the working condition was judged though comparing the frequency of pulsating water pressure and the natural frequency of stop log gate. The results show that the frequency of pulsating water pressure is low and changing as the time go on; The frequency components have obvious change in different intake schemes, the pulsating energy and the frequency components are more and more abundant with the increasing intake altitude. The frequency of pulsating water pressure is less during the process of outlet than the stop log gates, so the resonance can be avoided.