| 摘要 |
PROBLEM TO BE SOLVED: To measure the flow velocity and the flow rate of a fluid to be measured, with high accuracy. SOLUTION: A flowmeter 10 measures the flow rate on the basis of the flow velocity, which is measured by the flow-velocity measuring apparatus 12. The measuring apparatus 12 comprises an antenna 16, which is installed on the outer circumference of a flowmeter body 14 in which the fluid to be measured flows, an ultrasonic sensor 19 which is installed in the downstream part of the antenna 16 by the antenna 16. Ultrasonic waves are directed at a prescribed angle to the fluid to be measured, which flows in a flow passage 24 formed inside the flowmeter body 14, and a heating region 26 is generated. Since the propagation speed of ultrasonic waves transmitted from an ultrasonic transmitter 18 is changed due to the difference in density due to the temperature difference of the fluid to be measured, when a change in the time which is elapsed until the ultrasonic waves transmitted from the transmitter 18 are received by an ultrasonic receiver 20 is monitored, the passage in the heating region 26 of the fluid to be measured can be detected precisely in a noncontacting manner, and the flow velocity and the flow rate of the fluid to be measured are determined.
|
