Pressure Pulsation Caused by the Interaction between the Perforated Plate Installed in a Pipe and the Fluid

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The pressure fluctuations accompanying the occurrence of lock-in caused by the vortex shedding from the perforated plate were examined experimentally. The results are summarized as follows:(1) When the lock-in occurs, the in-phase lateral vibration, (0,0) mode, of the perforated plate is generated. The plate displacement has a slight phase lag with respect to the differential pressure across the plate(2) The amplitudes and phases of pressure fluctuation along the pipe agree well with that calculated using continuity. Equation at the plate location under the non-cavitationg condition(3) During the cavitation occurrence the amplitudes and phases of pressure fluctuation deviate from the values for the non-cavitation, while the lock-in frequencies decrease gradually with increasing velocity(4) Natural frequency, 3750Hz, for (0,0) mode lateral vibration of the perforated plate is larger than the lock-in frequencies in this study(5) The lock-in phenomena is caused by the lateral vibration of the perforated plate due to the differential pressure fluctuation across the plate when the vortex-shedding frequencies agree with the natural frequencies of the liquid column, or the pressure loop is located at the just before or after the plate