| 摘要 |
PROBLEM TO BE SOLVED: To provide a flow rate measurement device capable of measuring a flow rate with high precision over the overall measurement range by setting a flow passage shape in a flow rate measurement part so as to form a laminar flow condition until a measurement maximum measurement flow rate. SOLUTION: This flow rate measurement device is provided with first and second ultrasonic oscillators arranged while putting a flow rate measurement part having a rectangular cross section between them, and on the basis of signals from the ultrasonic oscillators, a flow rate of fluid passing through the flow rate measurement part is measured. Each of a width dimension W and a height dimension H in the rectangular cross section of the flow rate measurement part and a long side dimension L of the flow rate measurement part is set so that a Reynolds number Re calculated according to the rectangular cross sectional shape of the flow rate measurement part is set below a critical Reynolds number Re0.
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