A compact and highly dynamic bidirectional flowmeter

Abstract

The present invention discloses a compact, high-dynamic-response, bidirectional flowmeter. This meter addresses the problem that existing flowmeters are unable to measure backflow in nuclear reactor thermal hydraulic experiments. By using a compact flow tube, a first differential pressure gauge connects the inlet section and the throat section of the flow tube to measure the pressure difference in the contraction section in real time; a second differential pressure gauge connects the outlet section and the throat section of the flow tube to measure the pressure difference in the diffusion section in real time; a data processor collects data from the first and second differential pressure gauges in real time, determines the flow direction of the liquid in the flow tube based on the data from the first differential pressure gauge, and calculates the corresponding flow rate based on the determination result. This allows accurate measurement of both forward and reverse flows through the flow tube.

Description

Technical Field

[0001] The invention belongs to the technical field of flow measurement in nuclear reactor thermal hydraulic experiments, and in particular relates to a compact high-dynamic response bidirectional flowmeter. Background Art

[0002] In recent years, small reactors have garnered widespread attention from research institutions around the world. These reactors commonly utilize helical tubular once-through steam generators. During the development of these generators, flow instability has been a key and challenging experimental challenge.

[0003] When flow instability occurs, the flow rate in the pipe fluctuates periodically with a certain period and amplitude. Therefore, it can be considered that backflow has occurred in the pipe, but existing flow meters cannot measure backflow flow. Summary of the Invention

[0004] The object of the present invention is to provide a compact high dynamic response bidirectional flow meter with high precision and high dynamic response function, which can accurately measure the flow rate flowing through the pipe in the forward or reverse direction.

[0005] In order to solve the above problems, the technical solution of the present invention is:

[0006] A compact high dynamic response bidirectional flow meter, comprising: a flow tube, a first differential pressure gauge, a second differential pressure gauge and a data processor;

[0007] The flow tube includes an inlet section, a contraction section, a throat section, a diffusion section and an outlet section connected in sequence;

[0008] The first differential pressure gauge is connected to the inlet section and the throat section, and is used to measure the pressure difference of the contraction section;

[0009] The second differential pressure gauge is connected to the outlet section and the throat section, and is used to measure the pressure difference of the diffusion section;

[0010] The data processor is connected to the first differential pressure gauge and the second differential pressure gauge, determines the flow direction of the liquid in the flow tube according to the data of the first differential pressure gauge, collects the data of the first differential pressure gauge and the second differential pressure gauge in real time, and calculates the corresponding flow rate according to the judgment result.

[0011] According to one embodiment of the present invention, the inlet section of the flow tube is cylindrical, the contraction section is truncated cone-shaped, and the throat section is cylindrical. The inlet section is connected to a first bottom surface of the contraction section, and a second bottom surface of the contraction section is connected to the throat section. The area of ​​the first bottom surface is greater than the area of ​​the second bottom surface.

[0012] The inlet section and the outlet section are symmetrical about the throat section, and the contraction section and the diffusion section are symmetrical about the throat section.

[0013] According to an embodiment of the present invention, the length of the opening section is not less than the diameter D thereof.

[0014] According to an embodiment of the present invention, the length of the throat section is not greater than its diameter d.

[0015] According to an embodiment of the present invention, a first pressure-taking hole is provided on the inlet section, and a distance between the first pressure-taking hole and a starting position of the throat section ranges from 1 / 4D to 1 / 2D.

[0016] According to an embodiment of the present invention, a second pressure-taking hole is provided on the throat section, and the second pressure-taking hole is located at the midpoint of the throat section.

[0017] According to an embodiment of the present invention, the ratio of the diameter of the throat section to the diameter of the opening section ranges from 0.3 to 0.75.

[0018] According to an embodiment of the present invention, the angle between two side edges of the contraction section is 21±1°.

[0019] According to an embodiment of the present invention, the flow tube is an integrally formed pipe.

[0020] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0021] The compact, high-dynamic-response, bidirectional flowmeter in one embodiment of the present invention addresses the problem that existing flowmeters are unable to measure backflow flow in nuclear reactor thermal hydraulic experiments. By using a compact flow tube, a first differential pressure gauge connects the inlet section and the throat section of the flow tube to measure the pressure difference in the contraction section in real time; a second differential pressure gauge connects the outlet section and the throat section of the flow tube to measure the pressure difference in the diffusion section in real time; a data processor collects data from the first and second differential pressure gauges in real time, determines the flow direction of the liquid in the flow tube based on the data from the first differential pressure gauge, and calculates the corresponding flow rate based on the determination result. This allows for accurate measurement of both forward and reverse flow through the flow tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of a compact high dynamic response bidirectional flowmeter in one embodiment of the present invention.

[0023] Description of reference numerals:

[0024] 1: flow tube; 101: inlet section; 102: contraction section; 103: throat section; 104: diffusion section; 105: outlet section; 106: first pressure-taking hole; 107: second pressure-taking hole; 108: third pressure-taking hole; 2: first differential pressure gauge; 3: second differential pressure gauge; 4: data processor. DETAILED DESCRIPTION

[0025] The following is a further detailed description of a compact high dynamic response bidirectional flowmeter proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description and claims.

[0026] In response to the problem that existing flow meters are unable to measure backflow flow in nuclear reactor thermal hydraulic experiments, this embodiment provides a compact, high-dynamic-response, bidirectional flow meter, comprising a flow tube, a first differential pressure gauge, a second differential pressure gauge, and a data processor; wherein the flow tube comprises an inlet section, a contraction section, a throat section, a diffusion section, and an outlet section connected in sequence; the first differential pressure gauge is connected to the inlet section and the throat section, and is used to measure the pressure difference of the contraction section in real time; the second differential pressure gauge is connected to the outlet section and the throat section, and is used to measure the pressure difference of the diffusion section in real time; the data processor is connected to the first differential pressure gauge and the second differential pressure gauge, and judges the flow direction of the liquid in the flow tube according to the data of the first differential pressure gauge, collects the data of the first differential pressure gauge and the second differential pressure gauge in real time, and calculates the corresponding flow according to the judgment result.

[0027] This flow tube features a compact design. One implementation method is as follows: the inlet section of the flow tube is cylindrical, the contraction section is truncated, and the throat section is cylindrical. The inlet section is connected to the first bottom surface of the contraction section, and the second bottom surface of the contraction section is connected to the throat section. The area of ​​the first bottom surface is greater than the area of ​​the second bottom surface. The inlet and outlet sections are symmetrical about the throat section, and the contraction and diffusion sections are symmetrical about the throat section. The length of the opening section is no less than its diameter D, and the length of the throat section is no greater than its diameter d. The ratio of the throat section diameter d to the opening section diameter D ranges from 0.3 to 0.75. The flow tube can be a pipe with separate connections or a one-piece pipe.

[0028] For details, please see Figure 1 The flow tube 1 includes a cylindrical inlet section 101 (97 mm long, 15 mm diameter), a frustoconical converging section 102 (25 mm long, θ1 = 20°), a cylindrical throat section 103 (6 mm long, 6 mm diameter), a frustoconical diverging section 104 (25 mm long, θ2 = 20°), and a cylindrical outlet section 105 (97 mm long, 15 mm diameter). The inlet section 101 and the outlet section 105 are symmetrical about the throat section 103, and the converging section 102 and the diverging section 104 are symmetrical about the throat section 103.

[0029] The inlet section 101 is provided with a first pressure hole 106, and the distance between the first pressure hole 106 and the starting position of the throat section 103 ranges from 1 / 4D to 1 / 2D. In this embodiment, the distance between the first pressure hole 106 and the starting position of the throat section 103 is 7.5 mm.

[0030] Correspondingly, a third pressure hole 108 is provided on the outlet section 105, and the distance between the third pressure hole 108 and the end position of the throat section 103 ranges from 1 / 4D to 1 / 2D. In this embodiment, the distance between the third pressure hole 108 and the end position of the throat section 103 is 7.5mm.

[0031] A second pressure-taking hole 107 is provided on the throat section 103 , and the second pressure-taking hole 107 is located at the midpoint of the throat section 103 .

[0032] The pressure tapping holes on the inlet section 101 and throat section 103 are connected to a first differential pressure gauge 2 (i.e., DP1), with the first pressure tapping hole 106 connected to the high-pressure end of the first differential pressure gauge and the second pressure tapping hole connected to the low-pressure end of the first differential pressure gauge, to measure the pressure differential across the contraction section 102. The pressure tapping holes on the throat section 103 and outlet section 105 are connected to a second differential pressure gauge 3 (i.e., DP2), with the third pressure tapping hole 108 connected to the high-pressure end of the second differential pressure gauge 3 and the second pressure tapping hole 107 connected to the low-pressure end of the second differential pressure gauge 3, to measure the pressure differential across the diffusion section 104.

[0033] The first differential pressure gauge 2 and the second differential pressure gauge 3 are connected to a data processor 4. The data processor 4 collects data from the first differential pressure gauge 2 and the second differential pressure gauge 3 in real time. Based on the data from the first differential pressure gauge 2, the data processor 4 determines the flow direction of the liquid in the flow tube 1 and calculates the corresponding flow rate based on the determination result. When the DP1 reading is greater than or equal to 0, the flow is determined to be forward, and the forward flow rate is calculated using DP1. Otherwise, the flow is determined to be reverse, and the reverse flow rate is calculated using DP2.

[0034] Flow measurement is based on the continuity equation and the Bernoulli equation. For example, when fluid flows through the flowmeter's throat section 103, the constricted shape of the throat section 103 increases the fluid velocity and reduces the static pressure, creating a pressure differential across the throat section 103. The greater the fluid flow rate, the greater the pressure differential across the throat section 103. The flow rate can then be calculated based on the pressure differential measurement using the following formula:

[0035]

[0036] Where, W: mass flow rate, kg / s;

[0037] C: outflow coefficient, obtained by calibration experiment;

[0038] ε: fluid expansion coefficient;

[0039] β: diameter ratio, d / D;

[0040] ρ: fluid density, kg / m 3 ;

[0041] ΔP: pressure difference, Pa.

[0042] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the scope of protection of the present invention.

Claims

1. A compact high dynamic response bidirectional flow meter, characterized in that: include: An integrally formed flow tube, a first differential pressure gauge, a second differential pressure gauge, and a data processor; The flow tube includes an inlet section, a contraction section, a throat section, a diffusion section and an outlet section which are sequentially connected along the axial direction and arranged symmetrically about the center of the throat section; The inlet section and the outlet section are cylindrical with equal diameter and the length of each section is not less than the diameter D; The contraction section and the diffusion section are truncated cone-shaped, the angle between the two sides of the contraction section is 21±1°, and the large end of the contraction section is seamlessly connected to the inlet section, and the small end is connected to the throat section; The throat segment is cylindrical, its length is no greater than its diameter d, and d / D is in the range of 0.3 to 0.75; The first differential pressure gauge is connected to the first pressure hole on the side wall of the inlet section and the second pressure hole at the midpoint of the throat section to measure the pressure difference of the contraction section in real time, wherein the distance between the first pressure hole and the starting end of the throat section is 1 / 4D to 1 / 2D; The second differential pressure gauge is connected to the second pressure taking hole through the third pressure taking hole on the side wall of the outlet section to measure the pressure difference of the diffusion section in real time; The data processor is connected to the first differential pressure gauge and the second differential pressure gauge, determines the flow direction of the liquid in the flow tube according to the data of the first differential pressure gauge, collects the data of the first differential pressure gauge and the second differential pressure gauge in real time, and calculates the corresponding flow rate according to the judgment result.

2. The compact high dynamic response bidirectional flowmeter according to claim 1, characterized in that: The inlet section is connected to a first bottom surface of the contraction section, the second bottom surface of the contraction section is connected to the throat section, and the area of ​​the first bottom surface is greater than the area of ​​the second bottom surface; The inlet section and the outlet section are symmetrical about the throat section, and the contraction section and the diffusion section are symmetrical about the throat section.

Images