JPH0882540A - Ultrasonic flow-rate measuring method and ultrasonic flowmeter - Google Patents

Abstract

PURPOSE: To enhance the measurement accuracy of the mean velocity in a pipe, and to improve the high accuracy in flow measurement. CONSTITUTION: Respective flow velocities A and B are measured with two sets of ultrasonic transducers T10 and R10 and T11 and R11, which are arranged in the orthogonally intersecting direction to the cross section of a pipe 1. The mean velocity is obtained based on the flow velocities A and B, and the correcting factors are obtained. The flow rate Q is obtained from the mean velocities and the correcting factors.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic flow rate measuring method for measuring a flow velocity from the propagation time of an ultrasonic wave in a pipe and obtaining a flow rate from this flow velocity, and an ultrasonic flowmeter therefor.

[0002]

2. Description of the Related Art An ultrasonic flowmeter propagates an ultrasonic wave through a fluid flowing in a pipe, detects a flow velocity v (m / s) from the propagation time of the ultrasonic wave at this time, and detects a flow rate Q (m) from this flow velocity. ³ /
h) Q = S · v (1) is calculated. In addition, S is a cross-sectional area (m
² )

FIG. 9 is a block diagram showing the general measurement principle of such an ultrasonic flowmeter. The pipe 1 is provided with ultrasonic transducers composed of a pair of transceivers T1, R1 and T2, R2.

In these ultrasonic transducers, the transmitters / receivers T1 and R1, and the transmitters / receivers T2 and R2 are arranged at a distance L, and one of the transmitters / receivers T1 and R1 has a fluid propagation direction of ultrasonic waves. The transmitters / receivers T2 and R2, which match the flow direction, are arranged such that the propagation direction of ultrasonic waves is opposite to the flow direction of the fluid.

The specific arrangement of the ultrasonic transducer with respect to the pipe 1 will be described. As shown in FIG. 10, a transmitter T1 of the ultrasonic transducer is provided with respect to the pipe 1 through a pedestal 2 at a predetermined angle. A receiver R1 of an ultrasonic transducer is arranged at a predetermined angle via the pedestal 3 in the ultrasonic wave propagation direction of the transmitter T1.

FIG. 11 is a layout view of the ultrasonic transducers as seen from the sectional direction of the pipe 1. Therefore, the transmitter T1 and the receiver R1 are arranged at a distance L, and the ultrasonic wave transmitted from the transmitter T1 enters the tube at an angle θ, propagates in the fluid, and reaches the receiver R1. Incident.

With such a structure, when the ultrasonic wave is transmitted from the transmitter T1, the ultrasonic wave propagates in the flow direction of the fluid and is received by the receiver R1, and the ultrasonic wave is transmitted from the other transmitter T2. Then, this ultrasonic wave propagates in the direction opposite to the flow of the fluid and is received by the receiver R2.

When the ultrasonic wave propagates in this way, its propagation velocities t1 and t2 become t1 = C + v (2) in the flow direction (downstream direction), where C is the speed of sound in the fluid, and are opposite to the flow. In the direction (downstream direction), t2 = Cv (3).

[0009] Since the intervals of the transceiver is L, and the difference τ propagation time, Δτ = t1-t2 = L / (C-v) -L / (C + v) = 2L · v / C 2 ... (4 ).

From this relationship, the velocity v of the fluid can be calculated by detecting and calculating the propagation time difference of the ultrasonic waves in the upstream and downstream directions.
Is calculated by the following equation. v = Δτ · C ² / 2L (5) Therefore, the flow rate Q flowing in the pipe 1 is obtained by substituting the velocity v of this fluid into the above equation (1).

By the way, since the ultrasonic flowmeter detects the flow velocity at one point between the ultrasonic transducers, the flow velocity in the pipe 1 is premised on a velocity distribution which becomes a laminar flow as shown in FIG. . Note that FIG. 12 (a) is a velocity distribution curve of laminar flow in the fluid flow direction, and FIG. 12 (b) is a contour line of the flow velocity seen from the cross section.

However, if there is a bend in the pipe or a valve or the like that makes the flow of the fluid turbulent on the upstream side or the downstream side of the ultrasonic transducer, the turbulent velocity distribution curve and It becomes the contour line of the flow velocity seen from the cross section.

When the velocity distribution of such a turbulent flow is obtained, in the flow velocity detection at one point between the ultrasonic transducers, the pipe 1
An error in the average speed in the above causes an error in measuring the flow rate Q.
Further, FIG. 14 shows a schematic example of the velocity distribution curves of the laminar flow and the turbulent flow of the fluid flowing in the pipe 1, and a change in the average flow velocity of the laminar flow and the turbulent flow causes a flow rate error.

That is, since the ultrasonic flowmeter obtains the flow rate by obtaining the average flow velocity v in the linear direction in which the ultrasonic wave propagates, the average flow velocity v is the average flow velocity of the in-pipe cross-sectional area of the pipe 1. Unlike the calibration, the difference between them causes an error.

In order to prevent the influence of these turbulences,
In order to make the velocity distribution curve of the fluid in the pipe a laminar flow, it is necessary to define the straight pipe length required on the upstream / downstream side of the ultrasonic transducer. However, such a straight pipe length becomes a constraint on the pipe design as the pipe diameter becomes larger, and the building becomes larger accordingly.

[0016]

As described above, since the flow rate of the ultrasonic flowmeter is calibrated on the assumption of laminar flow,
When a turbulent flow occurs, the flow velocity distribution changes and an error occurs. In reality, an error occurs because all the conditions of laminar flow cannot be satisfied due to the restrictions on the piping design as described above.

Therefore, it is an object of the present invention to provide an ultrasonic flow rate measuring method and an ultrasonic flow meter therefor, which can improve the measurement accuracy of the average flow velocity in a pipe to improve the accuracy of flow rate measurement.

[0018]

According to a first aspect of the present invention, at least two ultrasonic transducers are arranged in a direction orthogonal to the cross section of the pipe, and the average flow velocity is calculated from the respective flow velocity measured by these ultrasonic transducers. This is an ultrasonic flow rate measuring method that seeks to achieve the above object by obtaining the correction coefficient as well as the average flow velocity and the correction coefficient.

According to claim 2, at least two ultrasonic transducers arranged in a direction orthogonal to the cross section of the pipe, and an average flow velocity calculating means for obtaining an average flow velocity from the respective flow velocity measured by these ultrasonic transducers. And coefficient calculating means for obtaining a correction coefficient from each flow velocity measured by these ultrasonic transducers, and flow rate calculating means for obtaining a flow rate from the average flow velocity obtained by the average flow velocity calculating means and the correction coefficient obtained by the coefficient calculating means. Is an ultrasonic flowmeter that is equipped with the following.

According to the third aspect of the present invention, in an ultrasonic flow meter in which an ultrasonic wave is propagated in a pipe by an ultrasonic transducer to measure a flow velocity, and the flow rate is obtained from this flow velocity, a laminar flow region and turbulence with respect to the flow velocity in the pipe are obtained. A coefficient storage unit that stores a correction coefficient that defines the range of the flow region, and a flow coefficient calculation unit that reads a correction coefficient corresponding to the flow velocity measured by the ultrasonic transducer from the coefficient storage unit and obtains a flow rate based on the correction factor and the flow velocity. And an ultrasonic flowmeter which aims to achieve the above object.

According to claim 4, a plurality of ultrasonic transducers are arranged at each of a plurality of measuring points in the longitudinal direction of the pipe, and an average flow velocity of each flow velocity measured by each ultrasonic transducer is measured at each measuring point. This is an ultrasonic flow rate measuring method in which the average flow velocity is obtained from the average flow velocity at each measurement point, and the flow amount is obtained from the average flow velocity to achieve the above object.

According to the present invention, a plurality of ultrasonic transducers are arranged at a plurality of measuring points in the longitudinal direction of the pipe, and an average flow velocity is calculated from the flow velocity measured by each ultrasonic transducer at each measuring point. And a second average flow velocity calculation unit for obtaining the average flow velocity from the average flow velocity for each measurement point obtained by the first average flow velocity calculation unit. An ultrasonic flowmeter, which is provided with a flow rate calculating means for obtaining a flow rate from the average flow rate obtained by the average flow rate calculating means, and which is intended to achieve the above object.

[0023]

According to the first aspect, each flow velocity is measured by at least two ultrasonic transducers arranged in the direction orthogonal to the cross section of the pipe, and the average flow velocity is calculated from these flow velocity and the correction coefficient is calculated. The flow rate is calculated from the average flow velocity and the correction coefficient. Since the average flow rate is calculated in this way, the measurement accuracy of the average flow velocity in the pipe increases,
Along with this, the accuracy of flow rate measurement can be improved.

According to the second aspect, each flow velocity is measured by at least two ultrasonic transducers arranged in a direction orthogonal to the cross section of the pipe, the average flow velocity is calculated from these flow velocity by the average flow velocity calculating means, and the coefficient is calculated. The correction coefficient is calculated by the calculation means, and the flow rate is calculated by the flow rate calculation means from the average flow velocity and the correction coefficient.

According to the third aspect, the correction coefficient which defines the range of the laminar flow region and the turbulent flow region with respect to the flow velocity in the pipe is stored in the coefficient storage means, and the ultrasonic wave is propagated in the pipe by the ultrasonic transducer. When the flow velocity is measured and the flow rate is obtained from this flow velocity, the correction coefficient corresponding to the flow velocity measured by the ultrasonic transducer is read from the coefficient storage means, and the flow rate is obtained based on this correction coefficient and the flow velocity.

According to claim 4, a plurality of ultrasonic transducers are arranged at each of a plurality of measurement points in the longitudinal direction of the pipe, and an average flow velocity of each flow velocity measured by each ultrasonic transducer is measured at each of these measurement points. Then, the average flow velocity of each average flow velocity for each measurement point is calculated, and the flow rate is calculated from this average flow velocity.

According to the present invention, a plurality of ultrasonic transducers are arranged at each of a plurality of measurement points in the longitudinal direction of the pipe, and the average flow velocity of each flow velocity measured by each ultrasonic transducer is measured at each of these measurement points. The average flow velocity is calculated by the first average flow velocity calculation means, then the average flow velocity of each average flow velocity for each of these measurement points is calculated by the second average flow velocity calculation device, and the flow amount is calculated from this average flow velocity by the flow amount calculation device.

[0028]

【Example】

(1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an ultrasonic flowmeter. The pipe 1 has two ultrasonic transducers T10, R10 and T1 respectively in a direction orthogonal to the cross section of the pipe 1.
1, R11 are arranged.

That is, the transmitter T10 of one ultrasonic transducer and its receiver R10, and the transmitter T11 of its ultrasonic transducer and its receiver R11 are arranged.

Each of the receivers R10 and R11 of these ultrasonic transducers has an average flow rate calculating section 10 and a coefficient calculating section 1
Connected to 1. The average flow rate calculation unit 10 has a function of obtaining an average flow rate v ′ v ′ = (A + B) / 2 (6) from the flow rates A and B measured by the ultrasonic transducers T10, R10 and T11, R11. ing.

The coefficient calculator 11 calculates a correction coefficient k k = B / A (7) which is a ratio of the flow velocities A and B measured by the ultrasonic transducers T10, R10 and T11, R11. ) Is required.

The flow rate calculation unit 12 calculates the flow rate Q from the average flow velocity v ′ obtained by the average flow velocity calculation unit 10 and the correction coefficient k obtained by the coefficient calculation unit 11 as Q = k · S · v ′ (8) It has a function of calculating and obtaining. In addition, S is the pipe 1
Is the cross-sectional area of.

Next, the operation of the ultrasonic flowmeter constructed as described above will be described. When the ultrasonic wave is transmitted from the transmitter T10 of one ultrasonic transducer, this ultrasonic wave propagates through the fluid and is received by the receiver R10, and when the ultrasonic wave is transmitted from the transmitter T11 of the other ultrasonic transducer,
This ultrasonic wave also propagates through the fluid and is received by the receiver R11.

At this time, if the flow velocity distribution in the pipe 1 is in an ideal state, that is, if the flow velocity distribution is uniform with the center at the maximum flow rate (velocity distribution curve of laminar flow), it is detected by two ultrasonic transducers. The respective flow velocities A and B are the same.

However, if this velocity distribution curve deviates from the ideal state of the velocity distribution as shown in FIG. 2 and becomes a velocity distribution curve of turbulence, each velocity A, B detected by the two ultrasonic transducers. Will be different. Note that FIG.
(a) is the contour of the flow velocity seen from the cross section, and (b) is the velocity distribution curve of the laminar flow and turbulent flow of the fluid.

Therefore, the average flow rate calculation unit 10 inputs the respective flow velocities A and B measured by the two ultrasonic transducers T10, R10 and T11, R11, calculates the above equation (6) and calculates the average flow velocity v '. Ask for.

Along with this, the coefficient calculating section 11 inputs the respective flow velocities A and B measured by the two ultrasonic transducers T10, R10 and T11, R11, and the correction coefficient k which is the ratio of these flow velocities A and B is given as above. Calculate by calculating equation (7).

The flow rate calculation unit 12 receives the average flow velocity v'determined by the average flow velocity calculation unit 10 and the correction coefficient k determined by the coefficient calculation unit 11, and based on these average flow velocity v'and the correction coefficient k, the above equation ( 8) is calculated and the flow rate Q in the pipe 1
Ask for.

As described above, according to the first embodiment, the flow velocities A and B are measured by the two ultrasonic transducers arranged in the direction orthogonal to the cross section of the pipe 1, and the flow velocities A and B are measured. The average flow velocity v'is obtained from the correction coefficient k, and the average flow velocity v'and the correction coefficient k are obtained.
Since the flow rate Q is calculated from the above, the average flow velocity v ′ is calculated. Therefore, even when the flow velocity state shows a turbulent velocity distribution curve, the measurement accuracy of the average flow velocity v ′ in the pipe 1 increases. Along with this, the measurement accuracy of the flow rate Q can be improved.

That is, it is possible to correct the error caused by the deviation of the flow velocity distribution in the same cross section, and to improve the flow rate measurement accuracy. Although the average flow velocity is obtained using two ultrasonic transducers, the average flow velocity may be obtained by arranging a plurality of ultrasonic transducers without limitation to two. (2) Next, a second embodiment of the present invention will be described.

FIG. 3 is a block diagram of the ultrasonic flowmeter. The pipe 1 is provided with a pair of transmitter T20 and receiver R20 forming an ultrasonic transducer. FIG. 4 is a view of the arrangement of the transmitter T20 and the receiver R20 seen from the cross-sectional direction of the pipe 1.

The coefficient storage unit 20 stores a correction coefficient k which defines the range of the laminar flow region and the turbulent flow region with respect to the flow velocity v in the pipe 1.
'Is stored in advance. FIG. 5 is a diagram showing the relationship of the correction coefficient k ′ with respect to the flow velocity v. There is a region where laminar flow occurs with respect to this flow velocity v, and turbulent flow is present outside this laminar flow region. Therefore, the correction coefficient k'for this turbulent flow is stored.

Normally, the ultrasonic flowmeter defines performances such as accuracy assuming a laminar flow region. However, the turbulent flow region is detected from the value of the flow velocity v in the pipe 1, and this flow velocity v is detected. And the correction coefficient k'in the turbulent flow region are measured in advance and the coefficient storage unit 2
I remember 0.

The flow rate calculation unit 21 has a correction coefficient k corresponding to the flow velocity v measured by the ultrasonic transducers T20 and R20.
′ Is read from the coefficient storage unit 20, and the flow rate Q is calculated by calculating Q = k ′ · S · v (9) based on the correction coefficient k ′ and the flow velocity v.

Next, the operation of the ultrasonic flowmeter constructed as described above will be described. When an ultrasonic wave is transmitted from the transmitter T20 of the ultrasonic transducer, this ultrasonic wave propagates through the fluid and is received by the receiver R20.

The flow rate calculation unit 21 detects the flow velocity v from the propagation time of the ultrasonic wave at this time, and reads the correction coefficient k'corresponding to this flow velocity v from the coefficient storage unit 20. Next, the flow rate calculation unit 21 calculates the above equation based on the correction coefficient k ′ and the flow velocity v.
(9) is calculated to obtain the flow rate Q in the pipe 1.

As described above, according to the second embodiment, the correction coefficient k'that defines the range of the laminar flow region and the turbulent flow region with respect to the flow velocity v in the pipe 1 is stored in the coefficient storage unit 20, and the pipe 1
The ultrasonic wave is propagated in the inside to measure the flow velocity v, and the correction coefficient k ′ corresponding to this flow velocity v is read from the coefficient storage unit 20 to obtain the flow rate Q, so that the velocity distribution curve of the turbulent flow is shown. The turbulent flow is corrected to the laminar flow state by the correction coefficient k ′ even when the flow velocity is in a stable state, and the measurement accuracy of the average flow speed v ′ in the pipe 1 is increased, and the measurement accuracy of the flow rate Q is increased accordingly. Can be increased.

That is, since the measurement in the turbulent flow region is also possible, the required straight pipe length of the instrument may be short, the building itself can be downsized, and a volumetric flow system, etc. which does not require a straight pipe length in the past can be used. As a mechanical alternative to instruments that require maintenance, a maintenance-free and non-contact ultrasonic flow meter can also be applied, which is a great advantage. (3) Next, a third embodiment of the present invention will be described.

FIG. 6 is a block diagram of an ultrasonic flowmeter. In the pipe 1, three measurement points P1, P2, P3 are set at fixed intervals Lm, Ln.

These measurement points P1, P2, P3 are provided with three ultrasonic transducer groups M1, M2, M3 each having a transceiver as a pair. The arrangement of the transmitters / receivers of the ultrasonic transducer groups M1, M2, M3 will be described with respect to the ultrasonic transducer group M1. FIG. 7 is a layout diagram seen from the longitudinal direction of the pipe 1, and FIG. 8 is seen from the cross-sectional direction of the pipe 1. FIG.

That is, a plurality of transceivers T30 and R30, T31 and R31, ... T37 and R37 are arranged at the measurement point M1 of the pipe 1. These transceivers T30 and R30, T
31 and R31, ... T37 and R37 are installed on the circumference of the pipe 1 in the same plane. Note that, in FIG. 7, they are shown separately from the same plane for the sake of illustration.

At the other measurement points M2 and M3 as well,
These transceivers T30 and R30, T31 and R31, ... T37 and R37
Similarly, a plurality of transceivers are provided. Each of the ultrasonic transducer groups M1 to M3 has a first
The average flow velocity calculation units 30 to 32 are connected.

These first average flow velocity calculators 30-32
Has a function of obtaining each average flow velocity Δτ1, Δτ2, Δτ3 from each flow velocity v measured by each ultrasonic transducer for each measurement point M1 to M3.

For example, the first average flow velocity calculating section 30 includes transmitters / receivers T30 and R30, T31 of each ultrasonic transducer.
And R31, ... Flow velocities v1 to v detected by T37 and R37
8 and receives the average flow velocity Δτ1 Δτ1 = (v1 + v2 + v3 + ... + v8) / 8 (10).

The second average flow velocity calculating section 33 uses these first
The average flow velocity V V = (Δτ1 + Δτ2 + Δτ3) / 3 (11) is calculated from the average flow velocity Δτ1 to Δτ3 for each of the measurement points M1 to M3 obtained by the average flow velocity calculating units 30 to 32. .

The flow rate calculation unit 34 has a function of obtaining the flow rate Q Q = k ″ · S · V (12) from the average flow velocity V obtained by the second average flow velocity calculation unit 33.

In this case, the correction coefficient k "is obtained from the respective average flow velocities .DELTA..tau.1 to .DELTA..tau.3 at the respective measurement points M1 to M3 according to a preset relationship. Next, the operation of the ultrasonic flowmeter constructed as described above. Will be described.

At each measurement point M1 to M3, for example, each transceiver T30 and R30 of each ultrasonic transducer,
T31 and R31, ... T37 and R37 are ultrasonic pipes 1
It transmits in and receives the propagated ultrasonic waves.

The first average flow velocity calculating units 30 to 32 at these measurement points M1 to M3 calculate the average flow velocity Δτ1 to Δτ3 for each measurement point M1 to M3 from each flow velocity v measured by each ultrasonic transducer. The above formula (1
0) is calculated.

The second average flow velocity calculating section 33 uses the first
The average flow velocity V is calculated from the average flow velocity Δτ1 to Δτ3 for each of the measurement points M1 to M3 obtained by the average flow velocity calculation units 30 to 32 of the above equation (11).

Then, the flow rate calculation unit 34 obtains the flow rate Q from the average flow velocity V obtained by the second average flow velocity calculation unit 33 by calculating the above equation (12). Thus, the third
According to the embodiment, the average flow velocities Δτ1 to Δτ3 of the flow velocities measured by the ultrasonic transducers are calculated for each of the plurality of measurement points M1 to M3, and then the average flow velocities Δτ1 to Δτ3 of each of the measurement points are averaged. Since the flow velocity V is obtained and the flow rate Q is obtained from this average flow velocity V, the flow velocity in the pipe 1 can be detected three-dimensionally, and the velocity distribution in the pipe 1 in the turbulent flow region can be disturbed or changed. However, the flow velocity can be measured with high accuracy and the flow rate can be measured with high accuracy by detecting at a plurality of measurement points M1 to M3 on the same line and on the same plane as the flow velocity detection at one measurement point.

Even if the fluid flow in the pipe 1 is a vortex state or the fluid is fluctuated due to pressure pulsation, the measurement is performed at each of the measurement points M1 to M3 in the fluid flow direction. Flow velocity can be measured.

The present invention is not limited to the above first to third embodiments, but may be modified as follows. For example, in the third embodiment, four pairs of ultrasonic transducers are arranged in the pipe 1 at each of the three measurement points M1 to M3. This is an example for three-dimensionally detecting the flow velocity in the pipe 1. Therefore, the more measurement points, the more accurately the average flow velocity can be measured.

In the ultrasonic transducer installed in the fluid flow direction, although the flow velocity may change due to the difference in the arrangement position, deceleration is ignored because it is in the same pipe 1 here, but deceleration is performed in advance. By multiplying by the coefficient, the flow velocity can be detected with higher accuracy.

Further, instead of the laminar flow region and the turbulent flow region, the flow velocity at the rated flow rate is V '± α, and when it deviates from this ± α, k' = V1 / V '(13) or k' = The correction coefficient k ′ may be calculated by V2 / V ′ (14) and the flow rate Q may be calculated by Q = k ′ · S · V ′ (15).

Further, the turbulent flow correction coefficient is obtained by the actual flow measurement, and the average flow velocity obtained in the above embodiment is multiplied by the coefficient to obtain the flow velocity. In addition, as a method of obtaining the velocity distribution of a solid body, in recent years, it is also effective to analyze the flow velocity distribution by simulation from the flow in the pipe 1 and the bend of the pipe 1 by a three-dimensional graphic computer to obtain the correction factor of the flow velocity. .

[0067]

As described above in detail, according to the present invention, the ultrasonic flow rate measuring method and the ultrasonic flow meter which can improve the accuracy of the flow rate measurement by increasing the measurement accuracy of the average flow velocity in the pipe. Can be provided.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a first embodiment of an ultrasonic flowmeter according to the present invention.

FIG. 2 is a diagram showing a distribution state of flow velocities to be measured by the same flow meter.

FIG. 3 is a configuration diagram showing a second embodiment of an ultrasonic flowmeter according to the present invention.

FIG. 4 is a diagram showing an arrangement of ultrasonic transducers in the flow meter.

FIG. 5 is a diagram showing a relationship between a flow velocity and a correction coefficient.

FIG. 6 is a configuration diagram showing a third embodiment of an ultrasonic flowmeter according to the present invention.

FIG. 7 is a diagram showing an arrangement of one ultrasonic transducer group in the same flow meter.

FIG. 8 is a diagram showing an arrangement of ultrasonic transducer groups viewed from a cross-sectional direction of a pipe.

FIG. 9 is a diagram showing a measurement principle of a conventional ultrasonic flowmeter.

FIG. 10 is a diagram showing an arrangement of ultrasonic transducers.

FIG. 11 is a view showing the arrangement of ultrasonic transducers as seen from the cross-sectional direction of the pipe.

FIG. 12 is a diagram showing a velocity distribution curve of laminar flow.

FIG. 13 is a diagram showing a velocity distribution curve of turbulent flow.

FIG. 14 is a diagram showing velocity distribution curves of laminar flow and turbulent flow.

[Explanation of Codes] 1 ... Piping, T10, R10, T11, R11 ... Ultrasonic transducer (transceiver), 10 ... Average flow rate calculation section, 11 ... Coefficient calculation section, 12 ... Flow rate calculation section, T20, R20 ... Ultrasonic wave Transducer (transceiver), 20 ... Coefficient storage unit, 21 ...
Flow rate calculator, M1, M2, M3 ... Ultrasonic transducer group, 30 to 32 ... First average flow velocity calculator, 33 ... Second
Mean flow velocity calculator, 34 ... Flow rate calculator.

Claims (5)

[Claims] 1. At least two ultrasonic transducers are arranged in a direction orthogonal to a cross section of a pipe, an average flow velocity is obtained from each flow velocity measured by these ultrasonic transducers, and a correction coefficient is obtained. An ultrasonic flow rate measuring method characterized in that the flow rate is obtained from a correction coefficient. 2. At least two ultrasonic transducers arranged in a direction orthogonal to the cross section of the pipe, an average flow velocity calculating means for obtaining an average flow velocity from the flow velocity measured by these ultrasonic transducers, and these ultrasonic waves. Coefficient calculating means for obtaining a correction coefficient from each flow velocity measured by the transducer, and flow rate calculating means for obtaining a flow rate from the average flow velocity obtained by the average flow velocity calculating means and the correction coefficient obtained by the coefficient calculating means are provided. An ultrasonic flowmeter characterized in that 3. An ultrasonic flowmeter, wherein ultrasonic waves are propagated in a pipe by an ultrasonic transducer to measure a flow velocity, and a flow rate is calculated from the flow velocity, in a range of a laminar flow region and a turbulent flow region with respect to the flow velocity in the pipe. And a flow rate calculating means for reading a correction coefficient corresponding to the flow velocity measured by the ultrasonic transducer from the coefficient storage means and calculating a flow rate based on the correction factor and the flow velocity. An ultrasonic flowmeter, comprising: 4. A plurality of ultrasonic transducers are arranged at each of a plurality of measurement points in the longitudinal direction of the pipe, and an average flow velocity of each flow velocity measured by each of the ultrasonic transducers is obtained at each of the measurement points, An ultrasonic flow rate measuring method characterized in that the average flow velocity is obtained from each average flow velocity at each measurement point, and the flow amount is obtained from this average flow velocity. 5. A plurality of ultrasonic transducers arranged respectively at a plurality of measurement points in the longitudinal direction of the pipe, and an average flow velocity is calculated from the flow velocity measured by the ultrasonic transducers at each measurement point. An average flow velocity calculation unit, a second average flow velocity calculation unit that obtains the average flow velocity from the average flow velocity of each measurement point obtained by the first average flow velocity calculation unit, and the second average flow velocity calculation unit. An ultrasonic flowmeter, comprising: a flow rate calculating means for obtaining a flow rate from the average flow velocity obtained by the calculating means.