CN111551219A

CN111551219A - Pitot tube structure

Info

Publication number: CN111551219A
Application number: CN202010421723.4A
Authority: CN
Inventors: 王小平; 贾肖肖; 李岚
Original assignee: Chongqing Academy of Science and Technology
Current assignee: Chongqing Academy of Science and Technology
Priority date: 2020-05-18
Filing date: 2020-05-18
Publication date: 2020-08-18
Anticipated expiration: 2040-05-18
Also published as: CN111551219B

Abstract

The invention provides a pitot tube structure.A fluid collecting port of an inner tube is arranged on the wall of the lower end of the inner tube, and the outer tube and a middle tube are both hollow tube structures with openings at the upper end and the lower end; the upper end of the inner pipe is inserted into the lower end of the middle pipe to form a telescopic sleeve structure, the upper end of the middle pipe is inserted into the lower end of the outer pipe to form a telescopic sleeve structure, a middle pipe fluid collecting port is formed in the pipe wall of the lower end of the middle pipe, and an outer pipe fluid collecting port is formed in the pipe wall of the lower end of the outer pipe; the static pressure collection pipe is arranged on the outer wall of the outer pipe, and is directly communicated with the first pressure guide pipe; the buffer cavity is communicated with the upper end of the outer pipe, and the buffer cavity is communicated with the second pressure pipe. The invention has the advantage of more accurate measurement.

Description

Pitot tube structure

Technical Field

The invention relates to the technical field of fluid measurement, in particular to a pitot tube structure.

Background

For the flow measurement of the fluid in the pipeline, a pitot tube is generally used for measuring the total pressure and the static pressure of the fluid in the pipeline, and the flow rate of the fluid in the pipeline is obtained by calculating the difference value of the total pressure and the static pressure, so as to obtain the flow value of the fluid, such as an authorized publication number CN209992027U and a name of a plug-in pitot tube flowmeter. However, because the flow of the fluid in the pipe is very complicated, a boundary layer is formed on the pipe wall, the velocity distribution curve of the fluid in the pipe is shown in fig. 1, the fluid flows in the fluid pipe 17, the velocity is close to 0 at the pipe wall, the flow velocity is maximum at the pipe center, and the thickness of the boundary layer is not consistent for different pipe walls and fluids and flow velocities; the existing pitot tube generally only collects the total pressure and the static pressure of a certain point in a pipeline, so that the calculated fluid flow speed in the pipeline is inaccurate, and the static pressure measurement is also inaccurate due to the formation of vortex at a static pressure measuring port, so that the accuracy of a fluid flow value is influenced, particularly for large-caliber airflow, the insertion position of the existing pitot tube also influences the measurement result; on the other hand, the existing pitot tube is not strong in adaptability because the measuring head is not adjustable and can only be used for a pipeline with a certain pipe diameter.

Disclosure of Invention

Aiming at the problems of insufficient accuracy and poor adaptability of the conventional pitot tube for measuring the fluid flow, the invention provides a novel pitot tube structure.

According to the embodiment of the invention, the pitot tube structure comprises an outer tube, a middle tube and an inner tube, wherein the inner tube is a hollow tube structure with an opening at the upper end and a sealed lower end; the upper end of the inner pipe is inserted into the lower end of the middle pipe to form a telescopic sleeve structure, a first sealing ring is arranged between the inner pipe and the middle pipe, the upper end of the middle pipe is inserted into the lower end of the outer pipe to form a telescopic sleeve structure, a second sealing ring is arranged between the outer pipe and the middle pipe, a middle pipe fluid collecting port is arranged on the pipe wall of the lower end of the middle pipe, the middle pipe fluid collecting port is positioned between the first sealing ring and the second sealing ring, an outer pipe fluid collecting port is arranged on the pipe wall of the lower end of the outer pipe, and the outer pipe fluid collecting port is positioned; the static pressure collection pipe is characterized by further comprising a static pressure collection pipe and a first pressure guide pipe, wherein a static pressure collection port of the static pressure collection pipe is arranged on the outer wall of the outer pipe, and the static pressure collection pipe is directly communicated with the first pressure guide pipe; the buffer cavity is communicated with the upper end of the outer pipe, and the buffer cavity is communicated with the second pressure pipe.

The technical principle of the invention is as follows:

inserting the pitot tube structure into a fluid pipeline to be tested, enabling an inner tube fluid acquisition port, a middle tube fluid acquisition port and an outer tube fluid acquisition port to face to the direction of fluid flow, wherein fluid obtained at the acquisition ports comprises static pressure and dynamic pressure; the static pressure collecting pipe is arranged near the boundary layer to obtain more real static pressure, so that a difference value between the real total pressure and the real static pressure can be obtained.

Compared with the prior art, the invention has the following beneficial effects:

1. the metering result is more accurate. Because a plurality of collecting ports are arranged in the flow pipe, collected fluid flows into the buffer cavity, the total pressure of the fluid obtained in the buffer cavity is closer to the average total pressure on a certain section in the pipe, and the hydrostatic pressure near the boundary layer collected by the hydrostatic collecting pipe is also closer to the real hydrostatic pressure of the fluid, so that the flow velocity obtained by the pressure difference value is closer to the average flow velocity of the certain section in the pipe, and a more accurate flow metering result can be obtained.

2. The adaptability is stronger. Because the outer pipe, the middle pipe and the inner pipe are designed into three-stage sleeve structures, the total length and each section can be stretched and adjusted, so that one pitot tube flow measuring instrument can measure the flow of fluid in all flow pipes within a certain diameter range, and the pitot tube flow measuring instrument has better adaptability.

Drawings

FIG. 1 is a flow velocity profile of a fluid flowing within a fluid conduit according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a pitot tube structure according to an embodiment of the invention.

Fig. 3 is a schematic diagram of a pitot tube structure according to another embodiment of the invention.

Fig. 4 is a schematic view of the operating state of the pitot tube structure according to the embodiment of the invention.

In the above drawings: 1. an inner tube; 2. a middle tube; 3. an outer tube; 4. a first seal ring; 5. a second seal ring; 6. a static pressure collection pipe; 7. a buffer chamber; 8. a first pressure pipe; 9. a second pressure pipe; 11. an inner tube fluid collection port; 12. a first fluid via; 13. a differential pressure transmitter; 14. a flow totalizer; 15. a first switch; 16. a second switch; 17. a fluid conduit; 21. a middle tube fluid collection port; 22. a second fluid via; 31. an outer tube fluid collection port; 61. a static pressure collection port.

Detailed Description

The technical solution of the present invention is further explained with reference to the drawings and the embodiments.

The first embodiment is as follows:

as shown in fig. 2, an embodiment of the present invention provides a pitot tube structure, which includes an outer tube 3, a middle tube 2 and an inner tube 1, wherein the inner tube 1 is a hollow tube structure with an open upper end and a sealed lower end, a fluid collecting port 11 of the inner tube is arranged on a tube wall of the lower end of the inner tube 1, and the outer tube 3 and the middle tube 2 are both hollow tube structures with open upper and lower ends; the upper end of the inner pipe 1 is inserted into the lower end of the middle pipe 2 to form a telescopic sleeve structure, and a first sealing ring 4 is arranged between the inner pipe 1 and the middle pipe 2 to prevent fluid from passing through a gap between the outer wall of the inner pipe 1 and the inner wall of the middle pipe 2. The middle pipe 2 is inserted into the outer pipe 3 at the upper end and the lower end to form a telescopic sleeve structure, and a second sealing ring 5 is arranged between the outer pipe 3 and the middle pipe 2 to prevent fluid from passing through a gap between the inner wall of the outer pipe 3 and the outer wall of the middle pipe 2.

A middle pipe fluid collecting port 21 is formed in the pipe wall of the lower end of the middle pipe 2, the middle pipe fluid collecting port 21 is located between the first sealing ring 4 and the second sealing ring 5, an outer pipe fluid collecting port 31 is formed in the pipe wall of the lower end of the outer pipe 3, and the outer pipe fluid collecting port 31 is located above the second sealing ring 5; still include static pressure collection pipe 6 and first pressure pipe 8, the static pressure collection mouth 61 of static pressure collection pipe 6 sets up on the outer wall of outer tube 3, and static pressure collection pipe 6 directly communicates with first pressure pipe 8. Still include cushion chamber 7 and second pressure pipe 9, cushion chamber 7 and the upper end intercommunication of outer tube 3, cushion chamber 7 still communicates with second pressure pipe 9.

S1 is S2+ S3, S1 is the sectional area of the middle tube fluid collecting port 21, S2 is the sectional area of the outer tube fluid collecting port 31, and S3 is the sectional area of the inner tube fluid collecting port 11, so that the total pressure of the fluid entering the buffer cavity can be closer to the actual total pressure value of the fluid. As shown in fig. 4, the outer tube fluid collection port 31 and the static pressure collection port 61 are symmetrically arranged with respect to the central axis of the outer tube, so that the outer tube fluid collection port 31 faces the flow direction of the fluid to measure an accurate total pressure, and the static pressure collection port 61 faces away from the flow direction of the fluid to measure an accurate static pressure. The first pressure pipe 8 is provided with a first switch 15, and the second pressure pipe 9 is provided with a second switch 16.

As shown in fig. 4, the pitot tube structure is connected to a differential pressure transmitter 13 and a flow integrating instrument 14, two flow interfaces of the differential pressure transmitter 13 are respectively communicated with the first pressure guiding pipe 8 and the second pressure guiding pipe 9, and the flow integrating instrument 14 is electrically connected to the differential pressure transmitter 13.

Example two:

referring to fig. 3 and 4, a guide tube is provided on the inner tube and the middle tube, and the rest of the structure is the same as that of the first embodiment. The upper end of the inner tube 1 is provided with an inner tube guiding crown, the inner tube guiding crown is in clearance fit with the inner wall of the middle tube 2, the inner tube guiding crown or the upper end wall of the inner tube 1 is provided with a first fluid via hole 12, the inner tube guiding crown is arranged to ensure that the inner tube 1 has better stability in the middle tube 2, and the deformation of the telescopic tube body due to the disturbance of fluid is not easy to occur. The upper end of the middle pipe 2 is provided with a middle pipe guiding crown, the middle pipe guiding crown is in clearance fit with the inner wall of the outer pipe 3, and a second fluid through hole 22 is formed in the middle pipe guiding crown or the upper end wall of the middle pipe 2. The well pipe direction of setting is covered and is made well 2 stability in outer tube 3, is difficult for appearing the deformation of flexible body because of the disturbance of fluid.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims

1. The pitot tube structure is characterized by comprising an outer tube (3), a middle tube (2) and an inner tube (1), wherein the inner tube (1) is a hollow tube structure with an opening at the upper end and a sealed lower end, an inner tube fluid collecting port (11) is arranged on the tube wall at the lower end of the inner tube (1), and the outer tube (3) and the middle tube (2) are hollow tube structures with openings at the upper end and the lower end;

the upper end of the inner pipe (1) is inserted into the lower end of the middle pipe (2) to form a telescopic sleeve structure, a first sealing ring (4) is arranged between the inner pipe (1) and the middle pipe (2), the upper end of the middle pipe (2) is inserted into the lower end of the outer pipe (3) to form a telescopic sleeve structure, a second sealing ring (5) is arranged between the outer pipe (3) and the middle pipe (2), a middle pipe fluid collecting port (21) is arranged on the pipe wall of the lower end of the middle pipe (2), the middle pipe fluid collecting port (21) is positioned between the first sealing ring (4) and the second sealing ring (5), an outer pipe fluid collecting port (31) is arranged on the pipe wall of the lower end of the outer pipe (3), and the outer pipe fluid collecting port (31) is positioned above the second; the static pressure collecting pipe is characterized by further comprising a static pressure collecting pipe (6) and a first pressure guide pipe (8), a static pressure collecting port (61) of the static pressure collecting pipe (6) is formed in the outer wall of the outer pipe (3), and the static pressure collecting pipe (6) is directly communicated with the first pressure guide pipe (8); the buffer device is characterized by further comprising a buffer cavity (7) and a second pressure pipe (9), wherein the buffer cavity (7) is communicated with the upper end of the outer pipe (3), and the buffer cavity (7) is further communicated with the second pressure pipe (9).

2. A Pitot tube structure as defined in claim 1,

s1 ═ S2+ S3; wherein: s1 is the sectional area of the middle pipe fluid collecting port (21); s2 is the sectional area of the outer tube fluid collecting port (31); s3 is the sectional area of the inner tube fluid collection port (11).

3. A pitot tube structure according to claim 2, characterized in that said outer tube fluid collection port (31) and said static pressure collection port (61) are symmetrically arranged with respect to the central axis of the outer tube (3).

4. A pitot tube structure according to claim 3, characterized in that the first impulse pipe (8) is provided with a first switch (15).

5. A pitot tube structure according to claim 4, characterized in that the second impulse pipe (9) is provided with a second switch (16).

6. A pitot tube structure according to claim 1, characterized in that the upper end of the inner tube (1) is provided with an inner tube guiding crown which is in clearance fit with the inner wall of the middle tube (2), and the inner tube guiding crown or the upper end wall of the inner tube (1) is provided with a first fluid through hole (12).

7. A pitot tube structure according to claim 6, characterized in that the upper end of the middle tube (2) is provided with a middle tube guiding crown, the middle tube guiding crown is in clearance fit with the inner wall of the outer tube (3), and the middle tube guiding crown or the upper end wall of the middle tube (2) is provided with a second fluid passing hole (22).