Flow rate measuring device
AssigneeNational Institute of Advanced Industrial Science and Technology Atsuden Co., Ltd.
InventorsHarumichi Sato, Jun Akedo, Eiichi Murakami
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Abstract
[Problem] A flow rate measuring device in which guided waves are used, wherein the frequency of ultrasound is optimized; and energy injected from ultrasound transmission/reception elements is increased and the flow velocity sensitivity is raised; whereby the measurement accuracy is improved. [Solution] A frequency of an isolated peak of group velocities of guided waves, from among a plurality of peaks of group velocities of guided waves, and a resonance frequency of the ultrasound transmission element/reception element are set to agree; and the semi-amplitude of a power spectrum of ultrasound excited/received by the ultrasound transmission element/reception element is set to a value that does not overlap with another peak of group velocities.
Claims16
A flow rate measuring device comprising:
- a flow rate measurement part having two sides, wherein the flow rate measurement part comprises a first ultrasound transmission element/reception element on one side and a second ultrasound transmission element/reception element on the other side, with a distance L therebetween, wherein the resonance frequency of each ultrasound transmission element/reception element is a frequency of an isolated peak of group velocities of guided waves, from among a plurality of peaks of group velocities of guided waves, and wherein the semi-amplitude of a power spectrum of ultrasound excited/received by the ultrasound transmission element/reception elements is a value that does not overlap with another peak of group velocities;
- a flow rate computation circuit for calculating a propagation time T1 and a propagation time T2, wherein the flow rate computation circuit further obtains a flow velocity of a fluid from a propagation time difference between propagation time T1 and propagation time T2, the propagation time T1 being a time in which a first guided wave, excited by being driven by the first ultrasound transmission element/reception element, propagates from upstream to downstream to the second ultrasound transmission element/reception element set apart by gap L, and the propagation time T2 being a time in which a second guided wave, excited by being driven by the second ultrasound transmission element/reception element, propagates from downstream to upstream to the first ultrasound transmission element/reception element set apart by gap L.
Dependencies are inferred from the claim text.