JPS54121780A - Measuring apparatus of velocity of flow - Google Patents

Abstract

PURPOSE: To improve noise resistance and drift characteristic by displsing two sets of ultrasonic wave transmitters and receivers in a specific state.

CONSTITUTION: Two sets of ultrasonic wave transmitters and receivers 21, 22 and 23, 24 are installed by leaving spacings (2N - 1)l/2(N: 1, 2, 3..., l: spacing between von Karman's vortex streets 12), and the propagation paths of the ultrasonic wave signals from the ultrasonic transmitters 21, 23 are made the same direction in the direction nearly orthogonal to the long axis direction of a veotex making bar 11. The output of an ultrasonic wave oscillation circuit 3 causes the ultrasonic wave transmitters 21, 23 to transmit the ultrasonic waves simultaneously. The ultrasonic waves are then received in the ultrasonic wave receivers 22, 24 and are inputted to a phase difference demodulating circuit 4. Then, the von Karman's vortex streets 12 assume the state wherein while the upper vortex street is passing in one of the two sets of the ultrasonic wave propagating paths the lower vortex street passes in the other owing to their regular releasing, thus the noise owing to the vibrations of the pipeline 10 itself and the vibrations by pump and the diift components, etc. owing to the temperature of the measuring body are offset by a phase difference demodulating circuit 4, and the accurate velocity-of-flow signal may be obtained.

COPYRIGHT: (C)1979,JPO&Japio