| 摘要 |
PURPOSE:To improve the measuring accuracy regardless of changes in conditions by correcting the flow velocity to be measured with a given coefficient based on a time difference in the ultrasonic propagation corresponding to repeated switching of ultrasonic transmitter/receivers facing each other one on the upstream and the other on the downstream of the flow. CONSTITUTION:Waves of ultrasonic transmitter/receivers 3 and 4 facing each other one on the upstream the other on the downstream are repeatedly switched from reception to transmition and vice versa by a timing generation circuit 5, a transmission/reception change-over circuit 7 or the like and ultrasonic propagation information tu and td are generated from a control signal formation circuit 10 based on the equations I and II. An average propagation time difference or the like is computed by the equation IV corresponding to an average propagation time and a velocity based on the equations II and III with a gate circuit 12, a counter 13 or the like and memorized in a buffer 14. According to the contents of the memory, a correction coefficient or the like is read out corresponding to changes in the Reynolds coefficient of a memory circuit 21 of an information processing circuit 20 corrects a detected flow velocity signal in a computation circuit 21. Accordingly, the flow velocity can be measured at a high accuracy regardless of changes in the refractive index of ultrasonic pulses in the interface, the ultrasonic propagation speed depending on fluid temperature and composition, the Reynolds coefficient or the like. |
