JP2000234946A - Pulse-doppler-type ultrasonic current meter and ultrasonic flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately carry out measurement even if the velocity vector of fluid in a channel is inclined in regard to a channel axis by arranging a plurality of ultrasonic sensors while measurement lines being used as an ultrasonic radiation center line cross in the channel. SOLUTION: A pulse-Doppler-type ultrasonic current meter is equipped with ultrasonic sensors 1 and 2 with a frequency of 100 kHz-1 MHz, for example, on the outer wall of a channel. An ultrasonic wave is radiated into the channel from the sensor 1 at an angle θ1 to a wall surface, and a measurement line 6 is formed. The sensor 2 is installed, for example, in a symmetrical position, and a measurement line 7 is formed at an angle θ2 to the wall surface. The measurement lines 6 and 7 cross each other near a channel center line 4. Then, a reflection wave from a scattering particle 5 with a velocity vector C being inclined by an angle α for the center line 4 near a channel center returns to each of the sensors 1 and 2, velocity constituent C1 and C2 in the direction of each measurement line are measured, velocity Cm in an axial direction or the like is calculated by a specific method. The measurement line of the sensor 2 may be vertical to the wall surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulse Doppler type ultrasonic flow velocity for measuring the flow rate of a liquid flowing in a flow path of a hydraulic machine or a hydraulic equipment such as a pump, and measuring the flow velocity distribution and flow rate of the liquid in the flow path. The present invention relates to a meter and an ultrasonic flowmeter.

[0002]

2. Description of the Related Art As a conventional technique of an ultrasonic type flow meter or flow meter, a measuring sensor is attached to an outer wall of a flow path to measure a flow velocity distribution inside the flow path, or to integrate the measured flow velocity distribution to obtain a flow rate. And Japanese Patent Application Laid-Open Nos. 10-38651 and 10-239127 using a pulse Doppler ultrasonic flowmeter.
There is one described in Japanese Patent Publication No. The pulse Doppler ultrasonic flow meter measures the flow velocity distribution in the flow path and calculates the flow rate.Therefore, the straight pipe length upstream of the measuring section is shorter than that of the propagation time differential ultrasonic flow meter that is commonly used. It has the characteristic that high measurement accuracy can be obtained.

[0003]

The pulse Doppler type ultrasonic flow meter has excellent characteristics as described above. However, when measuring with only one ultrasonic sensor, the flow velocity vector to be measured is required. Is inclined with respect to the channel axis,
There is a disadvantage that a large error occurs between the measured value and the true value. This is because a two-dimensional flow can be measured only one-dimensionally by one ultrasonic sensor. As described above, in the measurement using one conventional sensor, only one-dimensional velocity vector in the axial direction on the measurement line can be measured.

An object of the present invention is to provide a hydraulic machine such as a pump and a hydraulic machine, which have a flow velocity vector of a liquid flowing in a flow channel inclined with respect to a flow channel axis even if the flow velocity vector of the liquid is inclined with respect to the flow channel axis. An object of the present invention is to provide a pulse Doppler ultrasonic flowmeter or an ultrasonic flowmeter capable of measuring a flow rate with high accuracy.

[0005]

In order to achieve the above object, a first feature of the present invention is a pulse Doppler ultrasonic current meter for measuring the flow rate of a hydraulic machine or a hydraulic equipment. And first and second ultrasonic sensors provided on the outer wall of the flow path constituting the flow path and emitting ultrasonic frequencies of 100 kHz to 1 MHz, and the ultrasonic radiation of the first ultrasonic sensor and the second ultrasonic sensor. The first ultrasonic sensor and the second ultrasonic sensor are arranged so that center lines (measurement lines) intersect each other in the flow path of the measurement target, and the measurement target area is determined based on signals received from the two ultrasonic sensors. It is provided with a means (arithmetic device) for calculating a velocity vector.

A second feature of the present invention is a pulse Doppler ultrasonic flowmeter for measuring a flow rate immediately after a discharge elbow outlet of a vertical mixed flow pump, provided on an outer wall of a discharge pipe section flow path immediately after the discharge elbow outlet. A first ultrasonic sensor and a second ultrasonic sensor, wherein the ultrasonic radiation center lines (measurement lines) of the first ultrasonic sensor and the second ultrasonic sensor intersect with each other in a flow path to be measured. In addition, the present invention is configured to calculate a velocity vector of a measurement target area based on reception signals from the two ultrasonic sensors.

A third feature of the present invention is that it comprises first, second and third ultrasonic sensors provided on an outer wall of a flow path constituting a flow path of a hydraulic machine or a hydraulic equipment, wherein the first and second ultrasonic sensors are provided. The second ultrasonic sensor is disposed at a position where their ultrasonic radiation center lines (measurement lines) pass on substantially the same plane, and the third ultrasonic sensor is used for measurement by the first or second ultrasonic sensor. The present invention is configured so that a three-dimensional velocity vector is calculated based on reception signals of the three ultrasonic sensors, which is installed at a position emitting a measurement line so as to be orthogonal to a plane formed by the lines.

A fourth feature of the present invention is that the first and second channels provided on the outer wall of the flow path constituting the flow path of the hydraulic machine or the hydraulic equipment are provided.
And the ultrasonic radiation center lines (measurement lines) of the first ultrasonic sensor and the second ultrasonic sensor are configured to intersect each other in the flow path to be measured. The configuration is such that the direction of the measurement line of the sensor is perpendicular to the flow channel axis direction (or the flow channel wall), and the velocity vector of the measurement target area is calculated based on the reception signals from the two ultrasonic sensors.

A fifth feature of the present invention is that the first and second channels provided on the outer wall of the flow path constituting the flow path of the hydraulic machine or the hydraulic equipment are provided.
And the ultrasonic radiation center lines (measurement lines) of the first ultrasonic sensor and the second ultrasonic sensor are configured to intersect each other in the flow path to be measured. The ultrasonic frequency applied to the sensor is set to a value higher than the ultrasonic frequency applied to the first ultrasonic sensor, and the velocity vector of the measurement target area is calculated based on the reception signals from the two ultrasonic sensors. It is in.

The first ultrasonic sensor may be fixedly installed on the outer wall surface of the flow channel, and the second ultrasonic sensor may be installed movably in the axial direction of the flow channel or in the circumferential direction of the flow channel. The operation times of the plurality of ultrasonic sensors may be shifted from each other, and the ultrasonic sensors may be operated one by one. It is also effective to provide a signal processor to which a plurality of ultrasonic sensors are connected via a sensor switch.

The frequency of the ultrasonic wave emitted from the ultrasonic sensor can be changed according to the width and diameter of the flow path to be measured. In particular, by setting the frequency of the applied ultrasonic wave to 100 kHz to 1 MHz, the measurable distance is set to 0.3 m to 2 m, and the flow velocity in the hydraulic machine flow path can be measured.

When the width of the ultrasonic beam from the ultrasonic sensor is set to be 1/10 to 1/30 of the diameter of the flow path to be measured of the fluid machine, a sufficiently high distance resolution with respect to the measurement distance can be obtained. Obtainable.

A sixth feature of the present invention is that a velocity component in a flow channel axial direction is calculated from a velocity vector obtained by a pulse Doppler type ultrasonic anemometer having the above characteristics, and the velocity in the flow channel axial direction is calculated. The flow rate is calculated by integrating over the road section.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A problem in the case where only one ultrasonic sensor is used in a pulse Doppler ultrasonic flow meter will be described below. FIG. 2 shows an example of a pulse Doppler type ultrasonic flow meter having one ultrasonic sensor.
Is attached to the outer wall 3 of the flow path, and ultrasonic waves are emitted from this sensor in the direction of the measurement line 6 in the flow path. Reference numeral 4 denotes a channel center axis. The incident ultrasonic waves are scattered by the scattered particles 5 of solids and bubbles flowing in the flow channel, and are taken in as a reception signal of the sensor 1. At this time, the captured ultrasonic signal includes a velocity component C _{1 in} the measurement line direction of the velocity vector C of the particle.
Due to the Doppler effect, the ultrasonic frequency changes by the value shown in the following equation. The frequency change Δf is measured, and the moving speed of the particle 5 in the axial direction (= flow speed C) is calculated according to Equation 1.
Is required.

[0015]

(Equation 1)

In this equation, a is the sound velocity of water in the flow channel, f ₀ is the frequency of the ultrasonic wave, Δf is the Doppler shift frequency, and θ ₁ is the angle between the incident direction of the ultrasonic wave and the flow path wall. But,
Equation 1 holds when the velocity vector is oriented in the axial direction of the flow path. If the flow velocity vector C to be measured is inclined by an angle α with respect to the flow path axis 4 as shown in FIG. 3 (such a flow has a swirl component in the flow at the outlet of a curved pipe or the like). The following problems exist. In other words, the velocity component C ₁ of the ultrasonic measurement line direction 6 of the velocity vector C is detected in the case as well as the sensor 1 in FIG. 2, the axial flow rate in the flow path by the number 1 3
In this case, C'm is required. However, the actual axial velocity of the velocity vector C is Cm, which is smaller than C'm. The ratio of these speeds is given by:

[0017]

(Equation 2)

Here, θ ₁ is the angle between the ultrasonic measurement line and the channel wall, and α is the angle between the velocity vector and the channel axis. This relationship is shown in FIG. According to FIG. 4, when the turning angle α is ± 5 degrees and θ ₁ = 72 degrees, the difference between the measured value and the true value reaches about 25%. This is because a two-dimensional flow can be measured only one-dimensionally by one ultrasonic sensor. As described above, in the measurement using one sensor, only one-dimensional velocity vector in the axial direction on the measurement line can be measured, so that the measurement accuracy may be reduced.

To solve the above problem, the present invention is as follows. That is, in addition to the conventional first ultrasonic sensor, a second ultrasonic sensor is arranged in the vicinity of the first ultrasonic sensor, and the measurement lines of the respective sensors intersect near the center of the flow path. Constitute. The current meter is configured to detect a two-dimensional velocity vector by two sensors having different directions, and combine the measured values from both sensors to obtain a measured flow velocity vector.

Further, in the present invention, the pulse Doppler type ultrasonic current meter is applied to the measurement of the flow velocity and flow rate of a hydraulic machine. (1) The metal pipe for the hydraulic machine has a thick metal wall.
In order to facilitate transmission and reception of ultrasonic waves, the ultrasonic output of the ultrasonic sensor is increased.

Further, by using an ultrasonic beam width much smaller than the width and diameter of the flow path to be measured, the measurement resolution in the flow path is increased, and the flow velocity distribution in the flow path can be grasped.

(2) As the frequency of the ultrasonic wave to be applied,
100kHz, suitable for measurement in the flow path of hydraulic machinery
It is possible to measure a large flow velocity with a large measurement width at a frequency of １1 MHz.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a view for explaining a specific embodiment in which the present invention is applied to a circular pipe portion immediately after a discharge bend portion of the vertical mixed flow pump shown in FIG. 13 and a measurement principle in this embodiment.
The first ultrasonic sensor 1 is installed on an outer wall 3 of a flow path through which water flows. A piezoelectric element (not shown) is mounted in the sensor 1 at an angle to the wall surface, and an ultrasonic wave is emitted from the sensor 1 at an angle θ ₁ with respect to the wall surface to form a measurement line 6. Is done. On the other hand, the second ultrasonic sensor 2 is similarly installed on the outer wall 3 of the flow channel at a position symmetrical with respect to the center axis 4 of the flow channel. From this sensor 2, a measurement line 7 is formed at an angle θ ₂ with the inner wall of the flow path. Both measurement lines 6 and 7 intersect near the center line 4 of the flow path. Each of the sensors 1 and 2 is connected to a signal processor (arithmetic device) (see FIG. 11) of the pulse Doppler ultrasonic flow meter, and is configured to measure the flow velocity distribution in the flow path.

It is assumed that the scattering particles 5 existing near the center of the flow path have a velocity vector C inclined by an angle α with respect to the central axis 4. The ultrasonic waves emitted from the ultrasonic sensors 1 and 2 are reflected and scattered by the particles 5, and the reflected ultrasonic waves return to the respective sensors 1 and 2 as input signals.
The velocity components C ₁ and C _{2 in the} respective measurement line directions are measured. When these velocities are obtained, the inclination angle α of the flow velocity and the axial velocity Cm required for calculating the flow rate can be obtained by the following equation.

[0026]

(Equation 3)

[0027]

(Equation 4)

[0028]

(Equation 5)

Here, C: the flow velocity to be measured, α: the angle between the flow velocity vector C and the flow path axis, θ ₁ : the angle between the ultrasonic measurement line of the sensor 1 and the flow path wall, θ ₂ : The angle between the ultrasonic measurement line of the sensor 2 and the flow path wall.

From Expressions 3 and 4, the inclination angle α can be obtained by the following expression.

[0031]

(Equation 6)

At radial positions other than on the center line of the flow path, as shown in FIG. 5, the flow rates C ₁ and C ₁ on the respective measurement lines are compared with the measurement points 9 and 10 on the line 8 at a certain radial position from the center. Request C ₂ as well. Based the flow rate C ₂ measuring points 9 to 6 from the number 3 measuring line 7 is regarded as' virtual parallel measurement points 10 on the measurement line 7, it is possible to determine the axial velocity Cm at the measurement point 10 . Similarly, for the measurement points 12 and 13 on the line 11 at the radial position, an imaginary measurement line 7 ″ is assumed, and the flow velocity in the axial direction at the measurement point 12 can be similarly obtained. If the flow velocity calculation process is performed in this manner, even if the flow in the flow channel is inclined with respect to the flow channel axis, that is, even if the flow has a component in the radial direction, the measurement line 6 Can be accurately obtained, and the flow rate measurement accuracy can be improved.

FIG. 6 shows an example in which three ultrasonic sensors are used. In this example, the third ultrasonic sensor 2a is installed so that the measurement line 14 is formed in a direction perpendicular to the measurement plane formed by the measurement lines of the first and second sensors 1 and 2. ing. With this configuration, it is possible to measure the velocity component of the flow velocity vector in the measurement line 14 direction by the third sensor 2a. Therefore, a speed component C ₃ orthogonal to the two-dimensional speed vector C obtained in the example of FIG. 1 can be obtained, and the two-dimensional speed vector C and the speed vector C ₃ orthogonal thereto are combined to obtain a three-dimensional speed vector C ₃ . It is possible to obtain a velocity vector. As a result, it is possible to improve the flow rate measurement accuracy even for a flow path having a three-dimensional complicated internal flow.

FIG. 7 shows still another example. In this example, the measurement line of the second sensor 2 is configured to be perpendicular to the flow path wall 3 and the flow path center line 4. That is, the case where the angle θ ₂ between the measurement line of the second sensor 2 and the flow path wall is set to 90 degrees, and the method of obtaining the axial flow velocity is the same as the example of FIG. In this example, the surface of the piezoelectric element in the sensor 2 may be parallel to the end face of the sensor, so that the structure of the sensor can be simplified.

On the other hand, in a pulse Doppler type ultrasonic flowmeter or flowmeter, since the measured flow velocity is expressed by the above equation 1, it is necessary to accurately grasp the absolute value of the sound velocity of the liquid as the measurement fluid. . The sound speed of a liquid greatly changes depending on the temperature of the liquid and the content of gas contained in the liquid. Therefore,
If the sound velocity is also measured at the same time as the flow velocity measurement, the flow rate measurement accuracy can be improved. The sensor 2 in the example of FIG. 7 has a configuration suitable for measuring the sound velocity of the liquid in the flow path. That fired vertically ultrasonic waves from the sensor 2 flow passage, it receives the ultrasonic wave reflected by the opposite inner wall, by measuring the elapsed time T to receive from the launching, several acoustic velocity a _L liquid follows 7, it can be easily measured. That is,

[0036]

(Equation 7)

Here, D: diameter of the flow path, h: thickness of the flow path, a _s : sound velocity of the flow path material, T _s : time required for sound to reciprocate through the thickness of the flow path, _TL : The time required for sound to reciprocate in the flow path. As described above, in this example, the two-dimensional flow velocity can be measured, and the sound velocity of the liquid can be easily measured.

FIG. 8 shows still another example. In the example of FIG. 6, the emission times of the burst waves (several pulse-like waves) of the ultrasonic waves emitted from the sensors 1, 2, 3 are configured to be shifted at every ΔT time interval. The frequency of the ultrasonic waves added to each sensor is set to be the same or different for each sensor. With this configuration, when one sensor is operating, no ultrasonic wave is emitted from another sensor, so that there is almost no possibility of interference between the sensors, and a signal with a high S / N ratio is obtained. It is possible,
The flow measurement accuracy can be improved.

FIG. 9 shows that the sensor 2 shown in FIG. 1 is moved in the axial direction along the outer wall of the flow path, and the measurement line of the sensor 2 is changed to the measurement line 7 ″,
7, 7 ', and the intersection with the measurement line 6 of the sensor 1 is formed as 5 ", 5, 5', and the flow velocity at that point is obtained. In this way, measurement line 6
The above flow velocity distribution can be obtained more accurately.

FIG. 10 shows the sensor 2 shown in FIG.
Move in the circumferential direction along the line, and change the measurement line of the sensor 2 to the measurement line 1
4 ″, 14 (7), 14 ′ are moved in the circumferential direction to form an intersection 5 with the measurement line 6 of the sensor 1 and the velocity component of the flow inclined with respect to the plane of the measurement line 6 is detected. I do. In this way, it is possible to improve the measurement accuracy of the flow velocity and the measurement accuracy of the flow rate.

FIG. 11 shows a configuration in which input / output signals to the sensors 1, 2, 3 are connected to a signal processor 21 of a common pulse Doppler type ultrasonic flow meter via a sensor switch 20. . As described in the example of FIG. 8, the sensors do not need to operate at the same time, but may operate at intervals of ΔT. Therefore, in this example, the sensor switch 20 is configured to transmit and receive signals to and from the sensors 1, 2, 3, and the signal processor 21 at every time interval of ΔT. According to this example, the entire system can be configured with one expensive signal processor, and the cost can be reduced.

The frequency of the ultrasonic wave applied to the second ultrasonic sensor 2 can be set to a higher value than that of the first ultrasonic sensor 1. In the pulse Doppler type ultrasonic anemometer, the measurable flow velocity Vma
There are the following conditions of x regarding x and the measurement distance (depth) Xmax.

[0043]

(Equation 8)

Here, a: sound velocity of the liquid, f ₀ : frequency of the ultrasonic wave, θ: angle between the flow path wall and the measuring line. Number 8
Can be illustrated as shown in FIG. The parameter is the frequency of the applied ultrasonic wave. From these Equations 8 and FIG. 12, it can be seen that when the same distance is measured, the higher the frequency, the lower the measurable flow velocity value. on the other hand,
It is generally known that, when the frequency of an ultrasonic wave is increased, the wavelength is shortened and the resolution of measurement is improved, and that the higher the frequency is, the more the output per unit area of the ultrasonic sensor is increased. In the example of FIG.
Radial component Cr are very small compared to the flow rate C ₁ of the measurement line direction. Therefore, by setting the frequency of the ultrasonic wave applied to the second ultrasonic sensor 2 having a vertical measurement line in the flow path lower than the frequency applied to the first ultrasonic sensor 1, Measurement resolution can be improved and the size can be reduced.

FIG. 13 shows that the sensors 1 and 2 of the pulse Doppler type ultrasonic flow meter are installed in the discharge pipe 16 immediately after the discharge elbow outlet to measure the discharge amount of the vertical mixed flow pump 15 and the flow rate is measured. It is like that. The direction of the flow velocity vector 18 at the outlet of the discharge elbow is slightly inclined with respect to the flow path center line 19. Thus, the flow having the radial component is detected by the sensor 2, and the flow rate measurement with high accuracy can be performed. A gate valve 17 is provided downstream of the discharge pipe 16.
And its downstream part is buried underground. As described above, since the length of the straight pipe portion is very short, even if a normal propagation time difference type ultrasonic flowmeter is installed in the discharge pipe 16, high measurement accuracy cannot be obtained. However, by applying a pulse Doppler type ultrasonic flow meter using two sensors as in the present invention, it is possible to measure the discharge flow rate of a vertical mixed flow pump having a short straight pipe portion with high accuracy. become.

In the example shown in FIG. 14, the frequency of the ultrasonic wave to be applied is set to 100 kHz to 1 MHz, and the beam width B of the ultrasonic wave from the ultrasonic sensor is set to about 1 / the channel diameter d of the fluid machine to be measured. It is set so as to be 10/1/30. With this configuration, the following effects can be obtained.

For example, if an ultrasonic wave of about 2 MHz to several MHz used in a field such as a blood flow meter is applied, the maximum flow velocity in the flow path of the hydraulic machine is about 5 m / s, and the incident angle of the ultrasonic wave is usually about 70 degrees, the distance that can be measured in Equation 8 is 0.08 m. Considering that the flow path diameter of the hydraulic machine is usually about 0.3 m to 2 m, measurement in the flow path of the hydraulic machine becomes difficult. From the example shown in FIG. 12, the frequency of the ultrasonic wave applied in the present invention is 100 kHz.
Up to 1MHz, the measurable distance is 0.3m ~
2 m, which enabled measurement of the flow velocity in the hydraulic machine flow path.

The size of the ultrasonic sensor is set so that the ultrasonic beam width B is 1/10 to 1/30 of the flow path diameter d. Range resolution can be obtained.

Further, since the beam width B is equal to the size of the piezoelectric element for ultrasonic oscillation in the ultrasonic sensor, and the ultrasonic output is proportional to the area of the piezoelectric element, it passes through the metal wall constituting the pump discharge pipe. Enough ultrasonic output can be obtained. Therefore, it is possible for the received ultrasonic wave having the Doppler signal scattered by the scattered particles contained in the water in the flow path to reach the ultrasonic sensor with sufficient strength.
The ultrasonic sensor also has a sufficient size as a receiver, and a received wave can be obtained as a signal of a level necessary for subsequent signal processing.

[0050]

According to the present invention, not only the flow direction of the flow path but also a flow having a velocity component having a cross section perpendicular to the flow direction of the flow path can be measured. As a result, the measurement accuracy of the flow velocity or flow rate can be improved. it can. If this flow meter is applied to the measurement of the flow velocity and flow rate of the discharge pipe of a vertical mixed flow pump, high-precision measurement can be performed even at a measurement location where the length of the straight pipe portion is short.

Further, the frequency of the ultrasonic wave is set to 100 kHz to 1 kHz.
MHz or the ultrasonic beam width is 1/1 of the channel diameter.
By setting the value to about 0 to 1/30, it is possible to measure the flow velocity and the flow rate with high accuracy even on the metal flow path wall of the hydraulic machine through which the ultrasonic wave is difficult to pass.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view illustrating an example of a pulse Doppler type ultrasonic current meter (flow meter) having one ultrasonic sensor.

FIG. 3 is a longitudinal sectional view for explaining a problem in a case where a flow velocity vector to be measured is inclined with respect to a flow channel axis in the example of FIG. 2;

FIG. 4 is a diagram illustrating the relationship (meridional flow velocity ratio) between the inclination angle (swirl angle α) of the velocity vector of the fluid with respect to the flow path axis and the measured flow velocity in the example of FIG. 3;

FIG. 5 is a longitudinal sectional view for explaining the measurement principle in the embodiment shown in FIG. 1;

FIG. 6 is a cross-sectional view showing an example in which three ultrasonic sensors are used.

FIG. 7 is a longitudinal sectional view showing an example in which a measurement line of a second ultrasonic sensor is set to be perpendicular to a flow path wall or a flow path center line.

FIG. 8 is a diagram illustrating an example in which the emission times of the ultrasonic waves emitted from a plurality of ultrasonic sensors are shifted.

FIG. 9 is a longitudinal sectional view illustrating an example in which one ultrasonic sensor is moved in the axial direction along the outer wall of the flow channel.

FIG. 10 is a longitudinal sectional view illustrating an example in which one ultrasonic sensor is moved in the circumferential direction along the outer wall of the flow channel.

FIG. 11 is a block diagram illustrating an example in which input / output signals to a plurality of ultrasonic sensors are connected to one signal processor via a switch.

FIG. 12 is a diagram for explaining a relational expression of Equation 8 (relationship between flow velocity, measurement distance, and ultrasonic frequency).

FIG. 13 is a front view showing an example in which the present invention is applied to flow measurement of a vertical mixed flow pump.

FIG. 14 is a longitudinal sectional view illustrating a preferred example of a diameter of a flow path to be measured and a width of an ultrasonic beam of a fluid machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st ultrasonic sensor, 2 ... 2nd ultrasonic sensor, 2a ...
Third ultrasonic sensor, 3 ... flow path wall, 4 ... flow path central axis, 5 ...
Intersection of measurement lines of two ultrasonic sensors, 6: measurement line of sensor 1, 7: measurement line of sensor 2, 8: streamline parallel to flow path axis 4, 9: streamline 8 and measurement line 7 Intersection point, 10: Intersection point of measurement line 6 and stream line 8, 11 ... Stream line parallel to channel axis 4, 12 ... Intersection point of stream line 11 and measurement line 6, 13 ... Intersection point of measurement line 7 and stream line 11, 14: measurement line of sensor 2a, 15: vertical mixed flow pump, 16: discharge pipe, 17: gate valve, 18: velocity vector of discharge flow, 19: underground wall surface, 20: sensor switcher, 21
... Signal processor (means for calculating velocity vector; arithmetic unit).

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keiyoshi Katakura 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Information and Communication Division, Hitachi, Ltd. (72) Masayuki Yamada 603, Kandamachi, Tsuchiura-shi, Ibaraki Co., Ltd. 2F035 AA06 DA07 DA12

Claims (13)

[Claims] 1. A pulse Doppler type ultrasonic current meter for measuring a flow rate of a hydraulic machine or hydraulic equipment, wherein an ultrasonic frequency of 100 kHz to 1 MHz is provided on an outer wall of a flow path constituting a flow path of the hydraulic machine or hydraulic equipment. A first ultrasonic sensor and a second ultrasonic sensor for emission, wherein the ultrasonic radiation center lines (measurement lines) of the first ultrasonic sensor and the second ultrasonic sensor intersect each other in a flow path of a measurement target. A pulse Doppler ultrasonic flow velocity, comprising: a first ultrasonic sensor and a second ultrasonic sensor, and means for calculating a velocity vector of a measurement target area based on signals received from the two ultrasonic sensors. Total. 2. The method according to claim 1, wherein the first super-position is provided at one of the intersections of two measurement lines passing through the center of the flow path of the hydraulic machine or the hydraulic equipment and having different angles with the center axis of the flow path and the flow path wall. A pulse Doppler ultrasonic flow velocity, wherein an ultrasonic sensor is installed, a second ultrasonic sensor is installed at the other intersection, and a velocity vector of a measurement target area is calculated based on signals received from both sensors. Total. 3. A pulse Doppler ultrasonic velocimeter for measuring a flow rate immediately after a discharge elbow outlet of a vertical mixed flow pump, wherein a first and a second pipes are provided on an outer wall of a discharge pipe section flow path immediately after the discharge elbow outlet. Wherein the ultrasonic radiation center lines (measurement lines) of the first ultrasonic sensor and the second ultrasonic sensor intersect each other in the flow path of the measurement target, and the ultrasonic sensors A pulse Doppler ultrasonic velocity meter characterized in that a velocity vector of a measurement target area is calculated based on a reception signal from the apparatus. 4. A pulse Doppler ultrasonic current meter for measuring a flow rate of a hydraulic machine or a hydraulic device, wherein the first, second, and second ultrasonic flowmeters are provided on an outer wall of a flow path of the hydraulic machine or the hydraulic device. 3 ultrasonic sensors, wherein the first and second ultrasonic sensors are disposed at positions where their ultrasonic radiation center lines (measurement lines) pass on substantially the same plane, and the third ultrasonic sensor The sensor is installed at a position emitting a measurement line so as to be orthogonal to a plane formed by the measurement line of the first or second ultrasonic sensor, and a three-dimensional velocity vector based on reception signals of the three ultrasonic sensors. A Pard Doppler ultrasonic current meter characterized in that it is configured to calculate 5. A pulse Doppler ultrasonic current meter for measuring a flow rate of a hydraulic machine or hydraulic equipment, wherein the first and second supersonic waves are provided on an outer wall of a flow path constituting a flow path of the hydraulic machine or hydraulic equipment. An ultrasonic wave sensor, wherein the first ultrasonic sensor and the second ultrasonic sensor are configured such that ultrasonic radiation center lines (measurement lines) intersect each other in a flow path of a measurement target; A pulse Doppler, wherein a direction of a measurement line is perpendicular to a flow channel axial direction (or a flow channel wall), and a velocity vector of a measurement target area is calculated based on reception signals from the two ultrasonic sensors. Type ultrasonic current meter. 6. A pulse Doppler ultrasonic current meter for measuring a flow rate of a hydraulic machine or hydraulic equipment, wherein the first and second supersonic waves are provided on an outer wall of a flow path constituting a flow path of the hydraulic machine or hydraulic equipment. An ultrasonic wave sensor, wherein the first ultrasonic sensor and the second ultrasonic sensor are configured so that ultrasonic radiation center lines (measurement lines) intersect each other in a flow path to be measured; The ultrasonic frequency to be applied is set to a value higher than the ultrasonic frequency to be applied to the first ultrasonic sensor, and the velocity vector of the measurement target area is calculated based on the reception signals from the two ultrasonic sensors. Characteristic pulse Doppler ultrasonic current meter. 7. The ultrasonic sensor according to claim 1, wherein the first ultrasonic sensor is fixed to the outer wall surface of the flow channel, and the second ultrasonic sensor is movable in the axial direction of the flow channel or in the circumferential direction of the flow channel. The pulse Doppler ultrasonic current meter installed in. 8. A pulse according to claim 1, wherein the operation times of the plurality of ultrasonic sensors are shifted from each other, and the ultrasonic sensors are operated one by one. Doppler type ultrasonic current meter. 9. A pulse Doppler ultrasonic current meter according to claim 1, further comprising a signal processor to which a plurality of ultrasonic sensors are connected via a sensor switch. 10. A structure according to claim 1, wherein a frequency of an ultrasonic wave emitted from said ultrasonic sensor can be changed in accordance with a width and a diameter of a flow path to be measured. A pulse Doppler ultrasonic current meter characterized by the following. 11. An ultrasonic sensor according to claim 3, wherein the ultrasonic frequency emitted from the ultrasonic sensor is 100 kHz to 1 MHz.
A pulse Doppler type ultrasonic current meter characterized by being set to Hz. 12. The method according to claim 1, wherein the width of the ultrasonic beam from the ultrasonic sensor is set to be 1/10 to 1/30 of the diameter of the flow path to be measured of the fluid machine. Pulse Doppler ultrasonic flow meter. 13. A flow axis direction velocity component is calculated from a velocity vector obtained by the pulse Doppler ultrasonic velocity meter according to any one of claims 1 to 12, and the velocity in the flow path axial direction is calculated. A pulse Doppler ultrasonic flowmeter, wherein the flow rate is calculated by integrating over a cross section.