| 摘要 |
PURPOSE:To eliminate influence exercised by a mechanical vibration and to obtain a flow meter for ka rma n vortex which has a high SN ratio, by a method wherein a function for detecting a mechanical vibration is created by placing a cover over either of first and second piezo-vibrators which are positioned in the proximity of each other, and the output of the two piezo-vibration are composed. CONSTITUTION:A vortex generator 2 is placed in a line 1, and a securing member 5 is located at the rear of the generator 2. Piezo-vibrators 11 and 12 are secured at a bed seat, set in a protruding manner at the securing member 5, through the medium of a retainer spacer 17 by means of a screw 13. The piezo-vibrator 12 is inserted into a hole 9 in a cover 8 having a streamline section and being fastened to the securing member 5. If the piezo-vibrators 11 and 12 are structured such that they are polarized in reverse direction to each other, vibrations produced by ka rma n vortex and the line 1 are exerted on the piezo-vibrator 11, and the vibration by the line 1 is exerted on the piezo-vibrator 12. The vibrations produced by the line 1 equalize is magnitude at the piezo-vibrators 11 and 12, and are in the reverse direction. This permits the detection of only the vibration produced by the ka rma n vortex. |
