Patent ID: 7584065

Claim:
A Doppler ultrasonic flowmeter for measuring, using an ultrasonic Doppler shift, a flow rate of fluid flowing inside a conduit, comprising: ultrasonic wave transmission/reception means for transmitting to the fluid an ultrasonic pulse with an arbitrary pulse repetition frequency, and for receiving a resulting ultrasonic echo to extract a Doppler shift component through a predetermined process; flow velocity distribution calculation means for calculating a flow velocity distribution of the fluid based on the Doppler shift component extracted by the ultrasonic wave transmission/reception means; and flow rate calculation means for calculating a flow rate of the fluid based on the calculated flow velocity distribution of a predetermined integration range and a quantization error occurring to a spatial resolution wherein the flow rate calculation means calculates the flow rate (Q) based on the following equation: Q = ⁢ 2 ⁢ π ⁡ ( v 0 · r 0 ′ · Δ ⁢ ⁢ r 0 ′ + ∑ i = 1 N - 1 ⁢ v 1 · r i · Δ ⁢ ⁢ r i + v N · r N ′ · Δ ⁢ ⁢ r N ′ ) = ⁢ 2 ⁢ π [ v 0 · ( 1 2 · r 0 + r 1 2 ) · ( r 0 + r 1 2 ) + ∑ i = 1 N - 1 ⁢ ( r i · Δ ⁢ ⁢ r i ) · v i + v n · ⁢ ( 1 2 · ( D 2 + r N - 1 + r N 2 ) ) · ( D 2 - r N - 1 + r N 2 ) ] where ( 1 2 · r 0 + r 1 2 ) · ( r 0 + r 1 2 ) is a flow rate coefficient of a starting channel, (r i ·Δr i )·v i is a flow rate conversion factor, ( 1 2 · ( D 2 + r N - 1 + r N 2 ) ) · ( D 2 - r N - 1 + r N 2 ) is a flow rate coefficient of an end channel, and where v is the flow velocity of the respective channel, r is the distance from the center of the conduit to the center of the respective channel, Δr is the width of the respective channel.