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

本文对孔板涡脱落引起的闭锁现象进行了实验研究。结果表明：（1）当发生锁定时，多孔板产生同相横向振动，即（0，0）模态。板位移相对于跨板压差有微小的相位滞后。（2）沿管道沿着的压力波动的幅值和相位与用连续性方法计算的结果吻合较好。（3）在空化发生过程中，压力脉动的幅值和相位均偏离无空化时的值，而锁定频率随流速的增加而逐渐减小。（4）在（0，0）模态的横向振动大于本研究中的锁定频率。（5）锁定频率的计算结果表明：现象是由多孔板的横向振动引起的，该横向振动是由于当涡流-脱落频率与液柱的固有频率一致，或者压力环位于板的前或后

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