CN111551219A - a pitot tube structure - Google Patents

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

a pitot tube structure

technical field

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

Background technique

For the flow measurement of the fluid in the pipeline, the pitot tube is generally used for measurement. The pitot tube is used to measure the total pressure and static pressure of the fluid in the pipeline, and the flow velocity of the fluid in the pipeline is calculated by the difference between the total pressure and the static pressure. Obtain the flow rate value of the fluid, for example, the authorization announcement number is CN209992027U, and the name is a plug-in pitot tube flowmeter. However, since the flow of the fluid in the pipeline is very complicated, a boundary layer will also be formed on the pipe wall, and the velocity distribution curve of the fluid in the pipeline is shown in Figure 1. The fluid flows in the fluid pipeline 17, and at the pipe wall The velocity is close to 0, and the flow velocity is the largest at the pipe core. For different pipe walls, fluids and flow rates, the thickness of the boundary layer is also inconsistent; the existing pitot tubes generally only collect the total pressure and static pressure at a certain point in the pipe. This makes the calculated flow velocity of the fluid in the pipe inaccurate, and the eddy current is formed at the static pressure measurement port, which also makes the static pressure measurement inaccurate, which affects the accuracy of the fluid flow value, especially for large-diameter airflow. The insertion position of the pitot tube will also affect the measurement result; on the other hand, the existing pitot tube is not adaptable because the probe is not adjustable and can only be used for pipes of a certain diameter.

SUMMARY OF THE INVENTION

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

According to an embodiment of the present invention, a pitot tube structure includes an outer tube, a middle tube and an inner tube, the inner tube is a hollow tube structure with an upper end open and a lower end sealed, and an inner tube is provided on the lower end tube wall of the inner tube Tube fluid collection port, the outer tube and the middle tube are hollow tube structures with open upper and lower ends; the upper end of the inner tube is inserted into the lower end of the middle tube to form a retractable sleeve structure, the inner tube and the A first sealing ring is arranged between the middle tubes, the upper end of the middle tube is inserted into the lower end of the outer tube to form a telescopic sleeve structure, a second sealing ring is arranged between the outer tube and the middle tube, and the middle tube A middle pipe fluid collection port is arranged on the lower end pipe wall of the outer pipe, the middle pipe fluid collection port is located between the first sealing ring and the second sealing ring, and an outer pipe fluid collection port is arranged on the lower end pipe wall of the outer pipe, so The fluid collection port of the outer pipe is located above the second sealing ring; it also includes a static pressure collection pipe and a first pressure guide pipe, and the static pressure collection port of the static pressure collection pipe is arranged on the outer wall of the outer pipe, so The static pressure collection tube is directly communicated with the first pressure guiding tube; it also includes a buffer cavity and a second pressure guiding tube, the buffer cavity is communicated with the upper end of the outer tube, and the buffer cavity is also connected with the second pressure guiding tube. The pressure guiding tube is connected.

The technical principle of the present invention is:

Insert the pitot tube structure into the fluid pipeline to be measured, so that the fluid collection port of the inner pipe, the fluid collection port of the middle pipe and the fluid collection port of the outer pipe face the direction of fluid flow, and the fluid obtained at the collection port includes both static pressure and dynamic pressure. Since the middle pipe fluid collection port is responsible for collecting the total pressure at the center of the fluid pipe, the inner pipe fluid collection port and the outer pipe fluid collection port collect the total pressure of the fluid pipe near the boundary layer respectively, and the collected three fluids flow into the buffer chamber. The total pressure in the fluid pipeline that is closer to the average value is obtained in the buffer chamber; the static pressure collection tube is set near the boundary layer to obtain a more real static pressure, so that a more real difference between the total pressure and the static pressure can be obtained.

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

1. The measurement results are more accurate. Since multiple collection ports are set in the flow pipe, the collected fluid flows into the buffer chamber, and the total fluid pressure obtained in the buffer chamber is closer to the average total pressure on a certain section in the pipe, and the fluid near the boundary layer collected by the static pressure collection pipe The static pressure is also closer to the real static pressure of the fluid, so that the flow velocity derived from the differential pressure value is closer to the average flow velocity of a certain section in the pipe, so that a more accurate flow measurement result can be obtained.

2. It is more adaptable. Since the outer tube, middle tube and inner tube are designed as a three-stage casing structure, the total length and each section can be stretched and adjusted, so that a Pitot tube flowmeter can measure the fluid flow in all flow tubes within a certain diameter range , so as to have better adaptability.

Description of drawings

FIG. 1 is a flow velocity distribution diagram of a fluid flowing in a fluid pipeline 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 present invention.

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

FIG. 4 is a schematic diagram of a working state of a pitot tube structure according to an embodiment of the present invention.

In the above drawings: 1. inner tube; 2. middle tube; 3. outer tube; 4. first sealing ring; 5. second sealing ring; 6. static pressure collection tube; 7. buffer chamber; 8. first Pressure guiding tube; 9. Second pressure guiding tube; 11. Fluid collection port in inner tube; 12. First fluid through hole; 13. Differential pressure transmitter; 14. Flow totalizer; 15. First switch; 16 17, fluid pipeline; 21, middle pipe fluid collection port; 22, second fluid through hole; 31, outer pipe fluid collection port; 61, static pressure collection port.

Detailed ways

The technical solutions in the present invention will be further described below with reference to the accompanying drawings and embodiments.

Example 1:

As shown in FIG. 2 , an embodiment of the present invention proposes a pitot tube structure, including an outer tube 3 , a middle tube 2 and an inner tube 1 . The inner tube 1 is a hollow tube structure with an upper end open and a lower end sealed. There is an inner tube fluid collection port 11 on the tube wall, the outer tube 3 and the middle tube 2 are hollow tube structures with openings at the upper and lower ends; the upper end of the inner tube 1 is inserted into the lower end of the middle tube 2 to form a retractable casing structure, and the inner tube 1 A first sealing ring 4 is arranged between the middle tube 2 and the outer wall of the inner tube 1 to prevent fluid from passing through the gap between the outer wall of the inner tube 1 and the inner wall of the middle tube 2 . The upper end of the middle tube 2 is inserted into the lower end of the outer tube 3 to form a telescopic sleeve structure, and a second sealing ring 5 is arranged between the outer tube 3 and the middle tube 2 to prevent fluid from passing through the gap between the inner wall of the outer tube 3 and the outer wall of the middle tube 2 pass.

The middle pipe fluid collection port 21 is provided on the lower end pipe wall of the middle pipe 2, the middle pipe fluid collection port 21 is located between the first sealing ring 4 and the second sealing ring 5, and the outer pipe fluid collection port 21 is provided on the lower end pipe wall of the outer pipe 3. Collection port 31, the fluid collection port 31 of the outer tube is above the second sealing ring 5; it also includes a static pressure collection tube 6 and a first pressure guide tube 8, and the static pressure collection port 61 of the static pressure collection tube 6 is arranged on the outer wall of the outer tube 3 Above, the static pressure collection pipe 6 is directly communicated with the first pressure guiding pipe 8 . It also includes a buffer cavity 7 and a second pressure guiding tube 9 , the buffer cavity 7 is communicated with the upper end of the outer tube 3 , and the buffer cavity 7 is also communicated with the second pressure guiding tube 9 .

S1=S2+S3, S1 is the cross-sectional area of the fluid collection port 21 in the middle pipe, S2 is the cross-sectional area of the fluid collection port 31 in the outer pipe, and S3 is the cross-sectional area of the fluid collection port 11 in the inner pipe. The total pressure is closer to the true 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 is facing the flow direction of the fluid to measure the accurate total pressure, while the static pressure The collection port 61 is just opposite to the flow direction of the fluid to measure the accurate static pressure. The first pressure guiding tube 8 is provided with a first switch 15 , and the second pressure guiding tube 9 is provided with a second switch 16 .

As shown in Figure 4, the pitot tube structure is connected with a differential pressure transmitter 13 and a flow totalizer 14, and the 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, The flow totalizer 14 is electrically connected to the differential pressure transmitter 13 .

Embodiment 2:

As shown in Figures 3 and 4, guide tubes are 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 guide crown, the inner tube guide crown and the inner wall of the middle tube 2 are gap-fitted. The stability of the inner tube 1 in the middle tube 2 is better, and the deformation of the telescopic tube body is not easy to occur due to the disturbance of the fluid. The upper end of the middle tube 2 is provided with a middle tube guide crown, which is gap-fitted with the inner wall of the outer tube 3 , and a second fluid passage hole 22 is arranged on the middle tube guide crown or on the upper end wall of the middle tube 2 . The provided middle tube guide crown makes the stability of the middle tube 2 in the outer tube 3 better, and the deformation of the telescopic tube body is not easy to occur due to the disturbance of the fluid.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent substitutions without departing from the spirit and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims (7)

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).

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