JPS5470078A - Flowmeter - Google Patents

Abstract

PURPOSE:To measure flow rates with high accuracy without applying any special fabricating to piping by applying ultrasonic waves to fluid to create air bubbles and measuring the velocity of flow of the air bubbles thereby measuring the flow rate of the fluid. CONSTITUTION:An ultrasonic oscillator 12 for cavitation which generates ultrasonic waves so as to intersect perpendicularly with the direction of flow of fluid is mounted to the outside wall part of a conduit 11 in which fluid flows. Further an ultrasonic oscillator 13 and an ultrasonic receiver 14 are opposedly disposed on the outside wall part of the conduit 11 positioned on the downstream side of the distance L from this oscillator 12. Large output ultrasonic waves of, e.g., pulse form, are generated so as to intersect perpendicularly with the direction where fluid flows, from the oscillator 12, whereby air bubbles 15 are produced. When the air bubbles 15 arrive at the position of the oscillator 13, the ultrasonic waves being steadily generated from the oscillator 13 are attenuated by the air bubbles 15 and therefore this attenuation state is received with a receiver 14 and the arrival time of the air bubbles 15 is detected with a measuring apparatus 10. From the velocity of fluid V=L/t, the flow rate may be obtained by Q=S V if the section area of the conduit 11 is let to be S.