CN107064552B - Ultrasonic Doppler speed measuring device - Google Patents

Abstract

The invention discloses an ultrasonic Doppler speed measuring device, which is used for measuring the speed field of fluid in a container; the outer wall of the container is provided with at least two containing cavities, the ultrasonic Doppler speed measurement device comprises at least two detection components, and each detection component comprises a probe arranged in the corresponding containing cavity and a driving part for driving the corresponding probe to move; and in the motion process of each probe, the speed of each point of the fluid on the measuring line of the probe can be measured. Therefore, by arranging a plurality of movable probes, the speed of the fluid in the container can be obtained, and by reasonably arranging the positions and the directions of the probes, the measurement of the fluid speed field in the large area of the container is facilitated. Meanwhile, compared with the prior art, the ultrasonic Doppler speed measurement device can realize the measurement of the fluid speed field in the container by adopting fewer probes.

Description

Ultrasonic Doppler speed measuring device

Technical Field

The invention relates to the technical field of electronics, in particular to an ultrasonic Doppler speed measuring device.

Background

Energy and environment become one of the major problems affecting the progress and development of human society, and with the increasingly prominent problem of environmental pollution and the increasing demand for energy from human beings, new, clean, safe and reliable energy sources are required to be found to replace the existing fossil energy sources. At present, the energy source which is publicly known in the world and can be applied in a large scale is nuclear energy, wherein a liquid heavy metal reactor is one of the first stack types which are expected to realize commercial application in the currently recognized IV generation stack system due to the inherent safety and reliability of the liquid heavy metal reactor.

The thermodynamic research is one of the important research parts of liquid heavy metal reactors, and is the research basis of steady-state thermodynamic and transient accident safety analysis and engineering verification, and the velocity field measurement is a very important physical quantity in the thermodynamic research. Due to the characteristics of non-transparency, high temperature, strong corrosion and the like of liquid metal, a plurality of velocity field measurement methods for liquid metal environment have been developed, and UDV (ultra doppler velocity measurement) has been proved to be one of the best methods.

At present, in order to perform multi-dimensional velocity field measurement, Takeda et al arranges a circle of UDV probes on the outer side of a hemispherical device, each probe finishes velocity measurement in the direction of one measurement line, the velocity of intersection points of every two measurement lines can be synthesized, and velocity vector diagrams of all the intersection points form a two-dimensional velocity field on the plane. This method requires a large number of individual probes in order to obtain a two-dimensional velocity field in the plane. In addition, Lemmin et al in switzerland proposed a constant beam width probe (focusing probe) that can realize three-dimensional velocity field measurement on a measurement line by combining with other three general ultrasonic probes, but the measurement range is limited, and it is difficult to realize measurement over a large area.

In view of the above-mentioned drawbacks of the velocity measuring device, it is desirable to provide an ultrasonic doppler velocity measuring device which is helpful for measuring a large-area velocity field of a fluid in a container and requires fewer probes in the measuring process.

Disclosure of Invention

In order to solve the above technical problems, an object of the present invention is to provide an ultrasonic doppler velocity measurement device for measuring a velocity field of a fluid in a container; the outer wall of the container is provided with at least two containing cavities, the ultrasonic Doppler speed measurement device comprises at least two detection components, and each detection component comprises a probe arranged in the corresponding containing cavity and a driving part for driving the corresponding probe to move;

and in the motion process of each probe, the speed of each point of the fluid on the measuring line of the probe can be measured.

The measurement line of the probe refers to the direction indicated by the axial direction of the probe, i.e. the propagation direction of the ultrasonic waves emitted by the probe. Therefore, when a certain probe moves, a plurality of measuring lines are arranged, and the speed of the fluid on each measuring line can be measured. Meanwhile, the ultrasonic Doppler speed measuring device comprises a plurality of detection assemblies, and the probe of each detection assembly can measure the speed of fluid on a plurality of measuring lines.

Therefore, by arranging a plurality of movable probes, the speed of the fluid in the container can be obtained, and by reasonably arranging the positions and the directions of the probes, the measurement of the fluid speed field in the large area of the container is facilitated. Meanwhile, compared with the prior art, the ultrasonic Doppler speed measurement device can realize the measurement of the fluid speed field in the container by adopting fewer probes.

Optionally, the outer wall of the container is provided with two cavities, namely a first cavity and a second cavity, the ultrasonic doppler velocity measurement device includes two detection assemblies, namely a first detection assembly and a second detection assembly, and a measurement line of a first probe in the first detection assembly intersects a measurement line of a second probe in the second detection assembly to form a predetermined plane, so as to measure a two-dimensional velocity field of each point of the fluid in the predetermined plane.

Optionally, the outer wall of the container is further provided with a third cavity, the ultrasonic doppler velocity measurement device further includes a third detection assembly, a third probe of the third detection assembly can move under the driving of the driving component, and in the moving process, each measurement line forms a measurement plane of the third probe, and the measurement plane and the predetermined plane intersect at a predetermined intersection line, so as to measure a three-dimensional velocity field of each point of the fluid on the predetermined intersection line.

Optionally, the driving component includes a rotating shaft and a power part for driving the rotating shaft to rotate, so that the first probe and the second probe rotate in the predetermined plane, and the third probe rotates in the measuring plane.

Optionally, the bottom wall of the cavity contacting the measuring end of the probe is an arc-shaped bottom wall, and the measuring end can move along the arc-shaped bottom wall in the rotation process of the probe.

Optionally, the driving part further includes a mounting bracket for supporting the probe, and the rotating shaft is fixed to the mounting bracket and drives the mounting bracket to rotate;

the mounting frame is connected with the corresponding probe through a linear guide part, so that the probe can move linearly along the axial direction of the probe relative to the mounting frame under the action of the linear guide part.

Optionally, the mounting rack is hollow, and two ends of the mounting rack along the axial direction of the probe are provided with guide holes for the probe to pass through and slide in;

the inner cavity of the mounting frame is provided with a spring in a compressed state along the axial direction of the probe, and the spring and the guide hole are the linear guide part.

Optionally, the driving part further comprises a control part, wherein the control part can pre-store the rotation parameters corresponding to the probe as control signals and transmit the control signals to the power part to control the action of the power part.

Optionally, the first probe and the second probe intermittently rotate under the control of the control part, and when one probe is in a rotating state, the other probe stops rotating and is in a measuring state.

Optionally, a predetermined position of the outer wall surface of the container is recessed to form a bottom wall of the cavity, the bottom wall of the cavity is in contact with the measuring end corresponding to the probe, and a coupling agent is contained in each cavity.

Optionally, the coupling agent is water, high-temperature-resistant grease or liquid metal;

when the fluid to be measured is in a high-temperature environment, the coupling agent is low-oxidability liquid metal, and the melting point of the coupling agent is lower than the temperature of the fluid to be measured.

Optionally, the container is a vertically-placed cylindrical barrel body, the first containing cavity and the second containing cavity are respectively arranged at two ends of the outer wall of the barrel body along the same diameter, the heights of the first containing cavity and the second containing cavity are flush with the fluid level of the fluid to be measured in the barrel body, and the predetermined plane is a longitudinal section of the barrel body passing through the axis of the barrel body;

the third containing cavity is arranged at any position on the outer wall of the barrel body, which is different from the preset plane.

Optionally, the container is a horizontal cylindrical barrel body, the first containing cavity and the second containing cavity are formed in the upper side wall of the barrel body, the connecting line of the first containing cavity and the second containing cavity is along the axial direction of the barrel body, and the preset plane is a longitudinal section of the barrel body passing through the axial line of the barrel body;

the third containing cavity is arranged at any position on the outer wall of the barrel body, which is different from the preset plane.

Drawings

FIG. 1 is a schematic structural diagram of an ultrasonic Doppler velocity measurement device for measuring a fluid velocity field in a vertical cylindrical barrel body according to the present invention;

FIG. 2 is a schematic structural diagram of an ultrasonic Doppler velocity measurement device for measuring a fluid velocity field in a horizontal cylindrical barrel body according to the present invention;

FIG. 3 is a schematic diagram of a velocity measurement principle of the ultrasonic Doppler velocity measurement device in FIG. 1;

fig. 4 is a schematic structural view of the probe assembly of fig. 1 and 2.

In FIGS. 1-4:

1 container, 11 first cavity and 12 second cavity;

21 a first detection assembly, 22 a second detection assembly, 23 a power part, 24 a control part, 25 a rotating shaft, 26 a mounting rack, 261 a fastening screw, 27 a spring, 28 an ultrasonic Doppler detector, 281 a first probe, 282 a second probe, 283 a third probe, 29 a couplant;

m fluid level, A barrel axis.

Detailed Description

In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.

Referring to fig. 1-4, fig. 1 is a schematic structural diagram illustrating an ultrasonic doppler velocity measurement device for measuring a fluid velocity field in a vertical cylindrical barrel according to the present invention; FIG. 2 is a schematic structural diagram of an ultrasonic Doppler velocity measurement device for measuring a fluid velocity field in a horizontal cylindrical barrel body according to the present invention; FIG. 3 is a schematic diagram of a velocity measurement principle of the ultrasonic Doppler velocity measurement device in FIG. 1; fig. 4 is a schematic structural view of the probe assembly of fig. 1 and 2.

In a specific embodiment, the present invention provides an ultrasonic doppler velocity measurement device, which is used for measuring a velocity field of a fluid in a container 1, wherein the outer wall of the container 1 is provided with at least two cavities, and meanwhile, the ultrasonic doppler velocity measurement device includes at least two detection assemblies, each detection assembly includes a probe accommodated in a corresponding cavity, the probe is a probe of an ultrasonic doppler detector 28, and the velocity measurement principle is as follows: when the fluid in the container and the probe move relatively, the reflected signal of the ultrasonic wave emitted by the probe generates corresponding Doppler frequency shift, and the relative speed of the fluid to the probe can be measured according to the Doppler frequency shift, so that the speed of the fluid in the container can be measured.

Meanwhile, each detection assembly further comprises a driving part for driving the corresponding probe to move, and the speed of the fluid at each point on the measurement line of the probe can be measured in the movement process of each probe.

The measurement line of the probe refers to the direction indicated by the axial direction of the probe, i.e. the propagation direction of the ultrasonic waves emitted by the probe. Therefore, when a certain probe moves, a plurality of measuring lines are arranged, and the speed of the fluid on each measuring line can be measured. Meanwhile, the ultrasonic Doppler speed measuring device comprises a plurality of detection assemblies, and the probe of each detection assembly can measure the speed of fluid on a plurality of measuring lines.

Therefore, in this embodiment, by providing a plurality of movable probes, the velocity of the fluid in the container 1 can be obtained, and by reasonably setting the positions and directions of the probes, the measurement of the velocity field of the fluid in the large area of the container 1 can be facilitated. Meanwhile, compared with the prior art, the ultrasonic doppler velocity measurement device in the embodiment can realize the measurement of the fluid velocity field in the container 1 by using fewer probes.

Specifically, as shown in fig. 1 and fig. 2, the outer wall of the container 1 is provided with two cavities, namely a first cavity 11 and a second cavity 12, and correspondingly, the ultrasonic doppler velocity measurement device includes two detection assemblies, namely a first detection assembly 21 and a second detection assembly 22, and a first probe 281 of the first detection assembly 21 moves under the driving of a first driving part, a second probe 282 of the second detection assembly 22 moves under the driving of a second driving part, and during the movement of the two probes, a measurement line of the first probe 281 and a measurement line of the second probe 282 intersect in the predetermined plane all the time, so as to measure a two-dimensional velocity field of a fluid in the predetermined plane.

In the process that the first probe 281 and the second probe 282 move in the predetermined plane, the measurement lines of the first probe 281 and the second probe 282 intersect to form a large number of mesh points in the predetermined plane, and the first probe 281 and the second probe 282 can measure the velocity of the mesh points, so that the setting mode in this embodiment can obtain the two-dimensional velocity of each mesh point in the predetermined plane, and the two-dimensional velocity field of the fluid in the predetermined plane can be obtained by integrating the two-dimensional velocity of each mesh point in the predetermined plane. In addition, as will be appreciated by those skilled in the art, the more intersections of the first probe 281 and the second probe 282 measurement lines intersect, the more accurate the two-dimensional velocity field of the fluid within the predetermined plane.

With the arrangement, in the embodiment, because two intersecting straight lines can determine one plane, the two-dimensional velocity field of the fluid in the predetermined plane can be measured by arranging the probe with the two intersecting measuring lines, and fewer probes are used in the measuring process.

Further, the outer wall of the container 1 is further provided with a third containing cavity, and correspondingly, the ultrasonic doppler velocity measurement device further includes a third detection assembly, a third probe 283 of the third detection assembly can move under the driving of a corresponding third driving component, and in the movement process of the third probe 283, each measurement line forms a measurement plane of the third probe 283, the measurement plane intersects with the predetermined plane, and an intersection line of the measurement plane and the predetermined plane is defined as a predetermined intersection line, so that the ultrasonic doppler velocity measurement device can measure a three-dimensional velocity field of fluid at each point on the predetermined intersection line in the container 1.

As described above, since each point on the predetermined intersection line is the intersection of the three probe measurement lines during the movement of the third probe 283, in the present embodiment, the three-dimensional velocity field of each point on the predetermined intersection line in the container 1 can be measured by providing three moving probes. Simultaneously, through the relative position who changes three probe, can measure the three-dimensional velocity field of specific position as required, the setting mode is: in the three probes, the measuring lines of the two probes are coplanar and intersected, and the measuring line of the third probe is intersected with the plane different surface determined by the measuring lines of the two probes.

Therefore, in this embodiment, the three-dimensional velocity field of the fluid on the predetermined intersection line can be measured by providing the three detection assemblies, and meanwhile, the three-dimensional velocity field of the fluid at each point in the container 1 can be obtained by changing the positions of the three detection assemblies, and the number of probes used in the measurement process is small.

On the other hand, as shown in fig. 4, the driving components of the three probe assemblies each include a rotating shaft 25 and a power part 23 for driving the rotating shaft 25 to rotate, so that the first probe 281 and the second probe 282 rotate in the predetermined plane, and the third probe 283 rotates in the measuring plane (the plane where the measuring line of the third probe 283 is located).

Thus, the movement of each probe in the above embodiments is a rotation controlled by the rotating shaft 25 and the power unit 23. Of course, the driving member may be a linear driving member, and the probe may be driven by a linear driving member such as a linear motor to move linearly. However, the probe is driven to rotate by the rotating shaft 25 and the power part 23 in the embodiment, so that the occupied space is small, and the area of the measuring line is large in the probe rotating process, thereby being beneficial to measurement of a large-area fluid velocity field.

Based on this, as shown in fig. 1 and fig. 2, the bottom wall of each cavity contacting with the measuring end of the corresponding probe is an arc-shaped structure, so that the measuring end moves along the arc-shaped bottom wall during the rotation of the probe.

Of course, the bottom wall of the cavity does not need to be an arc-shaped structure, and may be in other shapes in the field, such as a linear shape, etc., but when the bottom wall is arc-shaped, it is beneficial to ensure that the probe always contacts with the bottom wall in the rotating process, and more importantly, it is beneficial to realize the stepping rotation of the probe, thereby improving the measurement accuracy. Simultaneously, when this arc diapire for one section arc on the probe rotation orbit, and the centre of rotation of probe when the centre of a circle department of arc diapire, can guarantee to probe rotatory in-process all the time with the contact of arc diapire.

Further, as shown in fig. 4, each of the driving components further includes a mounting bracket 26 for supporting the probe, and the rotating shaft 25 is fixed to the mounting bracket 26 and drives the mounting bracket 26 to rotate, so as to drive the probe to rotate. Meanwhile, the mounting bracket 26 is provided with a linear guide portion through which the probe is connected with the mounting bracket 26, and the probe can move linearly in its axial direction with respect to the mounting bracket 26 under the action of the linear guide portion.

As mentioned above, when the arc diapire that holds the chamber is one section arc on the probe rotation orbit, and the centre of rotation of probe when the centre of a circle department of arc diapire, can guarantee to probe rotatory in-process all the time with this arc diapire contact, however, this scheme is higher to the shape precision requirement that holds the chamber arc diapire, consequently, the processing degree of difficulty is great. And when the probe can be along its axial linear motion in mounting bracket 26, even there is the error in shape and the size that holds chamber arc diapire, the probe also can be along its axial linear motion under the drive of sharp guide part to make its measuring end contact with arc diapire all the time, guarantee this ultrasonic Doppler speed measuring device normal work, reduce simultaneously and hold the chamber processing degree of difficulty.

Specifically, as shown in fig. 4, the mounting bracket 26 is hollow, and two ends of the mounting bracket in the probe axial direction are provided with guide holes for the probe to pass through and slide in, and at the same time, the inner cavity of the mounting bracket 26 is further provided with a spring 27 in a compressed state in the probe axial direction, and the spring 27 and the guide holes are the linear guide portions.

The compression direction of the spring 27 is the axial direction of the probe, and therefore, the repulsive force direction thereof is also along the probe axial direction. In the rotation process of the probe, the measuring end of the probe is abutted to the bottom wall of the accommodating cavity, and under the action of resilience force of the spring 27 in a compressed state, the measuring end of the probe can be abutted to the bottom wall of the accommodating cavity no matter whether the shape of the bottom wall of the accommodating cavity is an accurate arc shape or not.

As shown in fig. 4, each of the driving members further includes a control unit 24, and the control unit 24 can pre-store rotation parameters such as a rotation angle, a rotation speed, and a rotation time of the corresponding probe as control signals and transmit the control signals to the corresponding power unit 23 to control the operation thereof.

The power unit 23 may be a stepping motor, and the control signal from the control unit 24 controls the stepping motor to rotate the output shaft of the stepping motor at a predetermined speed through a predetermined angle, so that the corresponding probe rotates through the predetermined angle within a predetermined time. Meanwhile, the angle rotated by the probe for each rotation is changed by changing the value of the control signal prestored in the control part 24, thereby changing the density of the measurement line of the probe and the time required for the whole measurement process.

Further, when the ultrasonic doppler velocity measurement device is used to measure a two-dimensional velocity field at each point in a predetermined plane, i.e. the first detection element 21 and the second detection element 22 are operated, the corresponding control portion 24 controls the rotation time of the first probe 281 to be equal to the measurement time of the second probe 282, and at the same time, controls one of the two probes to be in a rotation state and the other probe to be in a measurement state.

Wherein, the measuring time refers to the time when the probe is in a measuring state, and at the moment, the probe sends out ultrasonic waves to measure the speed of each point on the corresponding measuring line; the rotation time refers to a time when the probe is in a rotation state, at which the probe is rotated by the driving part to change the measurement position.

Therefore, in the present embodiment, when measuring a two-dimensional velocity field, the first probe 281 and the second probe 282 intermittently rotate, when the first probe 281 rotates (changes the measurement position), the second probe 282 is measuring (stops the rotation state), and when the second probe 282 finishes the measurement start rotation, the first probe 281 rotates to a specified position to start the measurement. In this case, the two probes are used to measure the velocity field in a manner that requires less time for the entire two-dimensional velocity field measurement process.

In the above embodiments, as shown in fig. 1 and fig. 2, the predetermined position of the outer wall surface of the container 1 is recessed to form the bottom wall of the above-mentioned cavity, that is, the bottom wall of the cavity is integrally formed with the container 1, and as mentioned above, the bottom wall of the cavity refers to the wall surface of the probe measuring end contacting with the cavity. Meanwhile, the bottom wall of the cavity is also connected with a baffle plate to form the cavities, and couplant 29 is arranged in each cavity.

The purpose of the coupling agent is to exclude air between the probe and the object to be detected, so that the ultrasonic waves can effectively penetrate into the workpiece to achieve the purpose of detection. Therefore, in the present embodiment, the probe is coupled with the outer wall of the container 1 through the coupling agent to realize the fluid velocity detection.

Specifically, the coupling agent 29 may be water, high temperature grease, or liquid metal. When the measured fluid is in a high-temperature environment, high-temperature grease or liquid metal is used as a coupling agent, wherein the selection of the liquid metal needs to meet the following requirements as much as possible: the liquid metal should be a substance with a low melting point or a melting point lower than the temperature of the fluid to be measured, and the liquid metal has a low oxidation degree in a high-temperature environment, and can be used as a coupling agent in the high-temperature environment only when the liquid metal meets the two requirements, such as metallic mercury, tin-lead, gallium-indium-tin alloy and the like.

Therefore, the ultrasonic doppler velocity measurement device in this embodiment can also be used for measuring the temperature of the high-temperature environment fluid, that is, can be used for measuring the flow velocity of the high-temperature fluid in the liquid heavy metal reactor in the nuclear energy field.

In the embodiment shown in fig. 1, the container 1 for containing the measured fluid is a vertically placed cylindrical barrel. The outer wall of the barrel body which is symmetrical relative to the axis of the barrel body is provided with the first containing cavity 11 and the second containing cavity 12 respectively, namely the two containing cavities are located at two ends of the cylindrical barrel body with the same diameter, and meanwhile, the height of the two containing cavities is flush with the fluid liquid level M of the measured fluid in the barrel body, so that the detection area is located below the fluid liquid level M. A first detection assembly 21 is arranged in the first cavity 11, and a second detection assembly 22 is arranged in the second cavity 12.

Obviously, the predetermined plane is a longitudinal section of the barrel body passing through the axis thereof, and the first detection assembly 21 and the second detection assembly 22 measure two-dimensional velocity fields of the fluid at various points in the predetermined plane. Wherein, the longitudinal section of the barrel body is a section parallel to the axis of the barrel body.

Meanwhile, the third containing cavity is arranged at any position on the outer wall of the barrel body, which is different from the preset plane, and a third detection assembly is arranged in the third containing cavity so as to test the three-dimensional velocity field of each point on the preset intersecting line.

In the embodiment shown in fig. 3, when the three detecting assemblies are at 90 ° to each other, the predetermined intersecting line is the barrel axis a of the cylindrical barrel, so the arrangement in fig. 3 can obtain a three-dimensional velocity field of the fluid at each point on the barrel axis, and the synthetic principle is the same as that of the three-dimensional space coordinate system.

In the embodiment shown in fig. 2, the container 1 for containing the measured fluid is a horizontal cylindrical barrel, and based on the orientation shown in fig. 2, the first cavity 11 and the second cavity 12 are opened on the upper side wall of the barrel, and the connection line of the two cavities is along the axial direction of the barrel. Meanwhile, a first detection assembly 21 is arranged in the first cavity 11, and a second detection assembly 22 is arranged in the second cavity 12.

Obviously, the predetermined plane is a longitudinal section of the barrel body passing through the axis thereof, and the first detection assembly 21 and the second detection assembly 22 measure two-dimensional velocity fields of the fluid at various points in the predetermined plane.

Meanwhile, a third containing cavity is arranged at any position of the outer wall of the barrel body, which is different from the preset plane, and a third detection assembly is arranged in the third containing cavity so as to test the three-dimensional velocity field of each point on the preset intersecting line.

The ultrasonic doppler velocity measurement device provided by the invention is described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.

Claims (13)

1. An ultrasonic Doppler speed measurement device is used for measuring the speed field of fluid in a container (1); the ultrasonic Doppler velocity measurement device is characterized in that at least two containing cavities are formed in the outer wall of the container (1), the ultrasonic Doppler velocity measurement device comprises at least two detection components, and each detection component comprises a probe arranged in the corresponding containing cavity and a driving part for driving the corresponding probe to move;

in the motion process of each probe, the speed of each point of the fluid on the measurement line of the probe can be measured;

the at least two detection assemblies comprise a first detection assembly (21) and a second detection assembly (22), and a measuring line of a first probe (281) in the first detection assembly (21) is intersected with a measuring line of a second probe (282) in the second detection assembly (22) to form a predetermined plane so as to measure a two-dimensional velocity field of the fluid at each point in the predetermined plane;

the driving component can drive the first probe (281) and the second probe (282) to rotate in the preset plane.

2. The ultrasonic doppler velocity measurement device according to claim 1, wherein two said cavities are provided on the outer wall of the container (1), which are a first cavity (11) and a second cavity (12), respectively, and the first detection assembly (21) and the second detection assembly (22) are provided in the first cavity (11) and the second cavity (12), respectively.

3. The ultrasonic doppler velocity measurement device according to claim 2, wherein a third cavity is further disposed on the outer wall of the container (1), the ultrasonic doppler velocity measurement device further comprises a third detection assembly, a third probe (283) of the third detection assembly is capable of moving under the driving of the driving component, and during the movement, each measurement line forms a measurement plane of the third probe (283), and the measurement plane intersects with the predetermined plane at a predetermined intersection line so as to measure a three-dimensional velocity field of the fluid at each point on the predetermined intersection line.

4. The ultrasonic Doppler velocity measurement device according to claim 3, wherein the driving member comprises a rotation shaft (25) and a power part (23) for driving the rotation shaft (25) to rotate, so that the first probe (281) and the second probe (282) rotate in the predetermined plane, and the third probe (283) rotates in the measurement plane.

5. The ultrasonic Doppler velocity measurement device according to claim 4, wherein a bottom wall of the cavity, which is in contact with the measurement end of the probe, is an arc-shaped bottom wall, and the measurement end can move along the arc-shaped bottom wall during the rotation of the probe.

6. The ultrasonic Doppler velocimetry device according to claim 4, wherein the driving means further comprises a mounting frame (26) for supporting the probe, the rotating shaft (25) is fixed to the mounting frame (26) and drives the mounting frame (26) to rotate;

the mounting rack (26) is connected with the corresponding probe through a linear guide part, so that the probe can move linearly relative to the mounting rack (26) along the axial direction of the probe under the action of the linear guide part.

7. The ultrasonic Doppler velocity measurement device according to claim 6, wherein the mounting frame (26) is hollow, and two ends of the mounting frame along the axial direction of the probe are provided with guide holes for the probe to pass through and slide in;

the inner cavity of the mounting rack (26) is provided with a spring (27) in a compressed state along the axial direction of the probe, and the spring (27) and the guide hole are the linear guide part.

8. The ultrasonic doppler velocimetry device according to claim 6, wherein said driving means further comprises a control section (24), said control section (24) being able to pre-store the rotation parameters corresponding to said probe as control signals and to transmit said control signals to said power section (23) to control the action thereof.

9. The ultrasonic doppler velocity measurement device according to claim 8, wherein the first probe (281) and the second probe (282) are intermittently rotated under the control of the control unit (24), and when one is in a rotation state, the other is in a measurement state in which the rotation is stopped.

10. An ultrasonic doppler velocimetry device according to any of claims 1-9 characterized in that a predetermined position of the outer wall surface of said container (1) is recessed to form a bottom wall of said cavity, said bottom wall of said cavity is in contact with the measuring end of the corresponding probe, and a coupling agent (29) is disposed in each of said cavities.

11. Ultrasonic doppler velocimetry device according to claim 10, characterized in that the coupling agent (29) is water, a high temperature resistant grease or a liquid metal substance;

when the fluid to be measured is in a high-temperature environment, the coupling agent (29) is low-oxidability liquid metal, and the melting point of the coupling agent is lower than the temperature of the fluid to be measured.

12. The ultrasonic Doppler velocity measurement device according to any one of claims 3 to 9, wherein the container (1) is a vertically-arranged cylindrical barrel body, the first cavity (11) and the second cavity (12) are respectively arranged at two ends of the outer wall of the barrel body along the same diameter, the heights of the first cavity (11) and the second cavity (12) are flush with the fluid level (M) of the fluid to be measured in the barrel body, and the predetermined plane is a longitudinal section of the barrel body passing through the axis of the barrel body;

the third containing cavity is arranged at any position on the outer wall of the barrel body, which is different from the preset plane.

13. The ultrasonic doppler velocity measurement device according to any one of claims 3 to 9, wherein the container (1) is a horizontal cylindrical barrel body, the first cavity (11) and the second cavity (12) are opened on the upper side wall of the barrel body, the connection line of the first cavity and the second cavity is along the axial direction of the barrel body, and the predetermined plane is a longitudinal section of the barrel body passing through the axial direction;

the third containing cavity is arranged at any position on the outer wall of the barrel body, which is different from the preset plane.

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