Venturi structure-based flow meter and bubble preparation multifunctional device

Abstract

The application belongs to the technical field of bubble preparation and flow measurement, and specifically discloses a multifunctional device for flow metering and bubble preparation based on a Venturi structure, which comprises a double Venturi channel structure, an annular pressure tapping pipe structure and a gas injection cavity, wherein the double Venturi channel structure comprises a primary Venturi structure for realizing single-phase flow metering and bubble preparation and a secondary Venturi structure for realizing gas-liquid two-phase flow metering; and the annular pressure tapping pipe structure specifically comprises a single-phase flow high-pressure annular pressure tapping pipe, a single-phase flow low-pressure annular pressure tapping pipe, a two-phase flow high-pressure annular pressure tapping pipe and a two-phase flow low-pressure annular pressure tapping pipe. The device integrates bubble preparation, single-phase flow metering of liquid medium and bubble flow gas-liquid two-phase flow metering, and can simultaneously meet the requirements of engineering application and experimental research for convenient and efficient bubble preparation and flow metering.

Description

Technical Field

[0001] This invention relates to the field of bubble preparation and flow measurement technology, specifically to a flow meter based on a Venturi structure and a multifunctional bubble preparation device. Background Technology

[0002] Compared to other two-phase flow patterns, bubbly flow has a large specific surface area, which can effectively improve heat and mass transfer efficiency. It also has advantages such as being environmentally friendly and easy to apply. Therefore, bubbly flow is widely used in environmental engineering, aerospace, chemical engineering, nuclear engineering and other fields.

[0003] Venturi channels are a common structural design in engineering equipment. This structure has many advantages such as easy processing, easy maintenance, reliable operation, and low energy consumption. Therefore, it is widely used in the design of flow meters, bubble generators, scrubbers, jet pumps and other devices.

[0004] In engineering applications of bubble generators, the most pressing concerns are how to efficiently prepare small-sized bubbles, provide the required gas content to meet practical engineering needs, and monitor the real-time flow pattern transition of the gas-liquid two-phase flow. Traditional single-channel Venturi bubble generators have limited bubble preparation capacity, are prone to backflow, require the simultaneous installation of multiple flow metering devices, and involve complex installation processes and cumbersome equipment maintenance. Therefore, there is an urgent need for a multifunctional device that integrates bubble preparation, single-phase flow metering of liquid media, and bubbly gas-liquid two-phase flow metering to simultaneously meet the needs of engineering applications and experimental research for convenient and efficient bubble preparation and flow metering. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a multifunctional device for flow meter and bubble preparation based on a Venturi structure. This device integrates bubble preparation, single-phase flow measurement of liquid medium, and two-phase flow measurement of bubbly gas-liquid flow, solving the problems mentioned in the background art and simultaneously meeting the needs of engineering applications and experimental research for convenient and efficient bubble preparation and flow measurement.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a multifunctional device for flow meter and bubble preparation based on a Venturi structure, comprising a dual Venturi channel structure, an annular pressure tapping tube structure, and an injection chamber. The dual Venturi channel structure includes a primary Venturi structure for realizing single-phase flow metering and bubble preparation, and a secondary Venturi structure for realizing gas-liquid two-phase flow metering. The annular pressure tapping tube structure specifically includes a single-phase flow high-pressure annular pressure tapping tube, a single-phase flow low-pressure annular pressure tapping tube, a two-phase flow high-pressure annular pressure tapping tube, and a two-phase flow low-pressure annular pressure tapping tube.

[0007] Preferably, the first-stage Venturi structure includes a first-stage Venturi converging section module for realizing single-phase flow metering and a first-stage Venturi expanding section module for realizing bubble preparation.

[0008] Preferably, the first-stage Venturi tapering module includes a channel inlet section, a first-stage Venturi tapering section, a first-stage Venturi throat, a single-phase high-pressure tapping hole, and a single-phase low-pressure tapping hole; the single-phase high-pressure tapping hole and the single-phase low-pressure tapping hole are respectively connected to the single-phase high-pressure annular tapping pipe and the single-phase low-pressure annular tapping pipe.

[0009] Preferably, the primary Venturi diffuser module includes a primary Venturi throat, a primary Venturi diffuser section, and an air inlet for the throat; the air inlet for the throat is connected to the air inlet, and the air inlet includes an air inlet and a flow equalization chamber.

[0010] Gas is injected through the gas injection chamber inlet. After passing through the gas injection chamber inlet and the flow equalization chamber, the gas enters the first-stage Venturi throat through the gas injection hole. Finally, the gas enters the near-wall strong turbulent region of the first-stage Venturi diffuser section with the high-speed water flow. The gas gains turbulent kinetic energy and is fully broken up to form bubbles.

[0011] Preferably, the secondary Venturi structure includes a secondary Venturi converging section module and a channel outlet section for realizing gas-liquid two-phase flow metering; the secondary Venturi converging section module specifically includes a secondary Venturi connecting straight pipe section, a secondary Venturi converging section, a secondary Venturi throat, a secondary Venturi expanding section, a two-phase flow high-pressure tap and a two-phase flow low-pressure tap; the two-phase flow high-pressure tap and the two-phase flow low-pressure tap are respectively connected to the two-phase flow high-pressure annular tap and the two-phase flow low-pressure annular tap.

[0012] Preferably, the angles of the first-level Venturi taper and the second-level Venturi taper are both α = 22.5°.

[0013] Preferably, the angles of the first-stage Venturi divergence and the second-stage Venturi divergence are both β = 12.5°.

[0014] Preferably, the inner diameters of the channel inlet section, the secondary Venturi connecting straight pipe section, and the channel outlet section are the same; the inner diameter of the channel inlet section is greater than the inner diameter of the primary Venturi throat, which is greater than the inner diameter of the primary Venturi throat.

[0015] Preferably, when implementing single-phase flow metering, a differential pressure transmitter is installed between the single-phase high-pressure annular pressure tap and the single-phase low-pressure annular pressure tap. The single-phase flow metering formula is as follows:

[0016]

[0017] In the formula, Wsp Let C be the mass flow rate of a single-phase flow, ψ be the first-order Venturi coefficient of thermal expansion, and C be the mass flow rate of a single-phase flow. d Here, ΔP is the first-order Venturi flow coefficient, A is the cross-sectional area of ​​the flow path, β is the first-order Venturi throat ratio, and ΔP is the flow rate coefficient. sp ρ is the pressure difference measured between the single-phase high-pressure annular pressure tap and the single-phase low-pressure annular pressure tap. sp The density is the density of the liquid medium.

[0018] Preferably, when measuring the flow rate of a gas-liquid two-phase flow, a differential pressure transmitter is installed between the high-pressure annular pressure tap and the low-pressure annular pressure tap of the two-phase flow. The flow rate of the two-phase flow can be determined by measuring the pressure difference, as follows:

[0019] Assuming the gas phase mass flow rate is as follows when the entire gas phase flows through the Venturi tube:

[0020]

[0021] In the formula, W g Let ΔP be the gas phase mass flow rate. g For the pressure drop of the entire gas phase flow, ρ g Density of the gaseous medium;

[0022] Assume the liquid mass flow rate is as follows when the entire liquid phase flows through the Venturi tube:

[0023]

[0024] In the formula, W l Let ΔP be the liquid phase mass flow rate. l For the pressure drop of the entire liquid phase flow, ρ l The density of the liquid medium;

[0025] Therefore, when the gas-liquid two-phase flow passes through the Venturi tube, the mass flow rates of the gas phase and the liquid phase are respectively:

[0026]

[0027]

[0028] In the formula, A g Let A be the cross-sectional area of ​​the gas phase in a gas-liquid two-phase flow. l Let ΔP be the cross-sectional area of ​​the liquid phase in a gas-liquid two-phase flow. TP The pressure difference between the gas and liquid phases measured by the high-pressure annular pressure tap and the low-pressure annular pressure tap of the two-phase flow is given by the following equation: A = AV, where A is the flow area at the throat of the Venturi tube. g +A l From this, we can obtain the pressure drop relationship for the ideal gas-liquid two-phase flow:

[0029]

[0030] Because actual gas-liquid two-phase flow has slip velocity and density differences, the actual pressure difference is greater than the two-phase flow pressure drop predicted by the above formula. A correction factor θ (θ>1) is introduced to correct and fit to the actual flow situation. The calculation formula is as follows:

[0031]

[0032] Based on the relationship between the measured actual flow rate and the pressure drop of the two-phase flow, θ is obtained by fitting the data and then combined with the measured pressure drop of the two-phase flow to obtain the actual two-phase flow mass flow rate.

[0033] The beneficial effects of this invention are:

[0034] 1) This invention achieves the requirement of high-efficiency bubble preparation through a dual Venturi channel. The secondary Venturi structure provides more sufficient energy conversion and a longer working process for bubble breakage. The primary Venturi throat design (the inner diameter of the throat is larger than the inner diameter of the throat) creates a local low-pressure region for the back-step flow, which is beneficial for gas intake and effectively improves bubble preparation efficiency, while effectively reducing the occurrence of backflow accidents. The dual Venturi channel of this invention has a two-stage Venturi structure, and the pressure difference can be measured by pressure sensors or differential pressure transmitters connected to high-pressure and low-pressure taps / pipes, respectively, thereby simultaneously realizing the flow measurement of upstream single-phase flow and downstream gas-liquid two-phase flow.

[0035] 2) The device of the present invention effectively solves the problems encountered in the combined use of multiple equipment in engineering, such as frequent equipment installation, complex process design, limited space and cumbersome maintenance. At the same time, it makes full use of the advantages of the Venturi structure, integrating functions such as single-phase flow and two-phase flow metering and bubble preparation. It can also be applied to various engineering application backgrounds, such as enhancing the bubble breaking process, pressure pulsation characteristics and flow pattern recognition, thereby improving engineering efficiency and saving engineering costs. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the device structure of the present invention;

[0037] Figure 2 This is a partial cross-sectional view of the first-level Venturi throat and the convex throat in an embodiment of the present invention;

[0038] Figure 3 These are half-sectional views of the front view and left view of the annular pressure tapping tube structure of the present invention.

[0039] Figure 4 These are half-sectional views of the front and left sides of the air injection chamber of the present invention.

[0040] Figure 5This is a schematic diagram showing the statistical comparison of bubble size distribution obtained by the present invention using only a first-level Venturi and by using both first- and second-level Venturi.

[0041] Figure 6 This is a schematic diagram illustrating the installation of the flow metering device in an embodiment of the present invention;

[0042] Figure 7 This is an installation diagram and a flowchart of the flow pattern recognition technology of the device of the present invention, which realizes the flow pattern discrimination function based on pressure pulsation signals.

[0043] In the diagram, 1-Dual Venturi channel structure; 2-Single-phase flow high-pressure annular pressure tap; 3-Single-phase flow low-pressure annular pressure tap; 4-Two-phase flow high-pressure annular pressure tap; 5-Two-phase flow low-pressure annular pressure tap; 6-Injection chamber; 11-Channel inlet section; 12-First-stage Venturi tapering section; 13-First-stage Venturi throat; 14-Single-phase flow high-pressure tap; 15-Single-phase flow low-pressure tap; 16-First-stage Venturi sudden expansion throat; 17-First-stage Venturi tapering section; 18-Sudden expansion throat injection port; 19-Second-stage Venturi connecting straight pipe section; 110-Second-stage Venturi tapering section; 111-Second-stage Venturi throat; 112-Second-stage Venturi tapering section; 113-Two-phase flow high-pressure tap; 114-Two-phase flow low-pressure tap; 115-Channel outlet section; 61-Injection chamber inlet; 62-Flow equalization chamber. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Please see Figures 1-7 This invention provides a technical solution: a multifunctional device for flow meter and bubble preparation based on a Venturi structure, such as... Figure 1 As shown, it includes a dual Venturi channel structure 1, an annular pressure tapping tube structure, and an injection chamber 6. The dual Venturi channel structure 1 includes a primary Venturi structure for single-phase flow metering and bubble preparation, and a secondary Venturi structure for gas-liquid two-phase flow metering. The annular pressure tapping tube structure specifically includes a single-phase flow high-pressure annular pressure tapping tube 2, a single-phase flow low-pressure annular pressure tapping tube 3, a two-phase flow high-pressure annular pressure tapping tube 4, and a two-phase flow low-pressure annular pressure tapping tube 5.

[0046] The device of this invention is characterized by having a dual Venturi channel structure 1, wherein the first-stage Venturi structure satisfies single-phase flow measurement and bubble preparation, and the second-stage Venturi structure satisfies two-phase flow measurement, integrating functions such as bubble preparation, single-phase flow measurement of liquid medium, and two-phase flow measurement of bubbly gas-liquid flow.

[0047] The first-stage Venturi structure includes a first-stage Venturi converging section module for realizing single-phase flow metering and a first-stage Venturi expanding section module for realizing bubble preparation.

[0048] Furthermore, the primary Venturi tapering module includes a channel inlet section 11, a primary Venturi tapering section 12, a primary Venturi throat 13, a single-phase flow high-pressure tap 14, and a single-phase flow low-pressure tap 15, constituting a typical primary device for differential pressure flow metering. A cross-sectional view of the primary Venturi throat is shown below. Figure 2 As shown. The single-phase high-pressure tap 14 and single-phase low-pressure tap 15 are respectively connected to the single-phase high-pressure annular tap 2 and the single-phase low-pressure annular tap 3, and the structure of the annular tap is as follows. Figure 3 As shown.

[0049] To measure the flow rate of a single-phase flow, a differential pressure transmitter (or two pressure sensors to measure the pressure difference) is installed between the high-pressure annular pressure tap 2 and the low-pressure annular pressure tap 3 of the single-phase flow. The single-phase flow rate can be determined by measuring the pressure difference. The formula for single-phase flow rate measurement is as follows:

[0050]

[0051] In the formula, W sp Let C be the mass flow rate of a single-phase flow, ψ be the first-order Venturi coefficient of thermal expansion, and C be the mass flow rate of a single-phase flow. d Here, ΔP is the first-order Venturi flow coefficient, A is the cross-sectional area of ​​the flow path, β is the first-order Venturi throat ratio, and ΔP is the flow rate coefficient. sp ρ is the pressure difference measured between the single-phase high-pressure annular pressure tap and the single-phase low-pressure annular pressure tap. sp The density is the density of the liquid medium.

[0052] Furthermore, the first-stage Venturi diffuser module includes a first-stage Venturi throat 16, a first-stage Venturi diffuser 17, and a throat injection port 18, constituting a typical Venturi-type bubble generator; the throat injection port 18 is connected to the injection chamber 6, as shown below. Figure 4 As shown, the gas injection chamber 6 includes a gas injection chamber inlet 61 and a flow equalization chamber 62.

[0053] Gas is injected through the gas injection chamber inlet 61. After passing through the gas injection chamber inlet and the flow equalization chamber, the gas enters the first-stage Venturi sudden expansion throat 16 through the gas injection hole 18. Injecting gas into the sudden expansion throat ensures that the gas is not carried into the mainstream area (the sudden expansion throat design can create a local low-pressure area for the back step flow, which is conducive to the intake of gas and effectively improves the bubble preparation efficiency, while effectively reducing the occurrence of backflow accidents). Finally, the gas enters the near-wall strong turbulent region of the first-stage Venturi gradual expansion section 17 with the high-speed water flow, which enhances the gas-liquid interaction process, so that the gas can obtain turbulent kinetic energy to the maximum extent and be fully fragmented, thereby obtaining smaller and more numerous bubbles.

[0054] Furthermore, the secondary Venturi structure includes a secondary Venturi converging section module and a channel outlet section 115 for realizing gas-liquid two-phase flow metering; the secondary Venturi converging section module specifically includes a secondary Venturi connecting straight pipe section 19, a secondary Venturi converging section 110, a secondary Venturi throat 111, a secondary Venturi expanding section 112, a two-phase flow high-pressure tap 113, and a two-phase flow low-pressure tap 114, constituting a typical primary device for differential pressure flow metering; the two-phase flow high-pressure tap 113 and the two-phase flow low-pressure tap 114 are respectively connected to the two-phase flow high-pressure annular tap 4 and the two-phase flow low-pressure annular tap 5.

[0055] When measuring the flow rate of a gas-liquid two-phase flow, a differential pressure transmitter is installed between the high-pressure annular pressure tap 4 and the low-pressure annular pressure tap 5 of the two-phase flow. The flow rate of the two-phase flow can be determined by measuring the pressure difference through secondary instruments (such as two pressure sensors or one differential pressure transmitter). The measurement principle is as follows:

[0056] Assuming the gas phase mass flow rate is as follows when the entire gas phase flows through the Venturi tube:

[0057]

[0058] In the formula, W g Let ΔP be the gas phase mass flow rate. g For the pressure drop of the entire gas phase flow, ρ g Density of the gaseous medium;

[0059] Assume the liquid mass flow rate is as follows when the entire liquid phase flows through the Venturi tube:

[0060]

[0061] In the formula, W l Let ΔP be the liquid phase mass flow rate. l For the pressure drop of the entire liquid phase flow, ρ l The density of the liquid medium;

[0062] ΔP g and ΔP lIt can be calculated based on a general single-phase flow pressure drop prediction model;

[0063] Therefore, when the gas-liquid two-phase flow passes through the Venturi tube, the mass flow rates of the gas phase and the liquid phase are respectively:

[0064]

[0065]

[0066] In the formula, A g Let A be the cross-sectional area of ​​the gas phase in a gas-liquid two-phase flow. l Let ΔP be the cross-sectional area of ​​the liquid phase in a gas-liquid two-phase flow. TP The pressure difference between the gas and liquid phases measured by the high-pressure annular pressure tap and the low-pressure annular pressure tap of the two-phase flow is given by the following equation: A = AV, where A is the flow area at the throat of the Venturi tube. g +A l From this, we can obtain the pressure drop relationship for the ideal gas-liquid two-phase flow:

[0067]

[0068] Because actual gas-liquid two-phase flow has slip velocity and density differences, the actual pressure difference is greater than the pressure drop predicted by the above formula. Therefore, a correction factor θ (θ>1) needs to be introduced to correct and fit the actual flow condition. The calculation formula is as follows:

[0069]

[0070] Based on the relationship between the measured actual flow rate and the pressure drop of the two-phase flow, θ is obtained through fitting. Combined with the measured pressure drop of the two-phase flow, the actual two-phase flow mass flow rate is obtained. Existing engineering and experimental data show that θ typically ranges from 1 < θ ≤ 1.8. Based on the relationship between pressure drop and flow rate in the above formula, θ is first obtained experimentally by measuring the relationship between the actual flow rate and the pressure drop of the two-phase flow and fitting it. In engineering applications, the actual two-phase flow mass flow rate can be obtained using a given θ and the measured pressure drop of the two-phase flow.

[0071] This invention discloses a flow meter and a multifunctional bubble generator based on a Venturi structure, comprising a dual Venturi channel structure 1, an annular pressure tapping tube structure, and an injection chamber 6. The dual Venturi channel structure comprises three parts: a single-phase flow metering section, wherein the channel inlet section 11 and the first-stage Venturi throat 13 are respectively provided with pressure taps, which are connected to the annular pressure tapping tube. Specifically, the single-phase flow high-pressure tap 14 and the single-phase flow low-pressure tap 15 are respectively connected to the single-phase flow high-pressure annular pressure tapping tube 2 and the single-phase flow low-pressure annular pressure tapping tube 3, allowing for the measurement of the single-phase flow rate; and a bubble generator section, comprising a throat with a sudden expansion structure, namely a first-stage Venturi sudden expansion throat 16, a sudden expansion throat injection port 18, and a first-stage Venturi gradual expansion section 17, with the injection port connected to the injection chamber. The cavity 6 is interconnected. The gas injection cavity 6 includes a gas injection inlet 61 and a flow equalization cavity 62. Gas is injected into the liquid through the gas injection cavity and injection port, and is broken up in the first-stage Venturi diffuser section to obtain a bubble flow. In the two-phase flow metering section, the second-stage Venturi connecting straight pipe section 19 and the second-stage Venturi throat 111 are respectively provided with pressure taps (two-phase flow high-pressure tap 113 and two-phase flow low-pressure tap 114), which are connected to annular pressure taps (two-phase flow high-pressure annular pressure tap 4 and two-phase flow low-pressure annular pressure tap 5), which can measure the two-phase flow rate and further break up the bubbles. This device provides a design scheme for flow metering and bubble preparation using a Venturi structure, which simplifies the application conditions of engineering equipment and has the advantages of convenient maintenance, low cost, and high efficiency in bubble preparation.

[0072] In this embodiment, the angles of the first-stage Venturi tapering section 12 (the acute angle formed by the straight pipe segment line passing through the same intersection point and the tapering section line) and the second-stage Venturi tapering section 110 are both α = 22.5°. The angles of the first-stage Venturi expanding section 17 (the acute angle formed by the straight pipe segment line passing through the same intersection point and the expanding section line) and the second-stage Venturi expanding section 112 are both β = 12.5°. The inner diameters of the channel inlet section 11, the second-stage Venturi connecting straight pipe section 19, and the channel outlet section 115 are all the same, 50 mm. The inner diameter of the channel inlet section > the inner diameter of the first-stage Venturi throat > the inner diameter of the first-stage Venturi throat. Specifically, the inner diameter of the first-stage Venturi throat is 25 mm, and the inner diameter of the first-stage Venturi throat is 27 mm. The pressure tapping pipe has an inner diameter of 4 mm, the pressure tapping hole diameter is 2 mm, and the air injection hole diameter of the throat is 1 mm.

[0073] The liquid medium is tap water, and the gaseous medium is powered by a water pump and an air compressor, respectively.

[0074] The double Venturi channel structure enables the efficient and high-volume preparation of bubbles. Standard flanges are welded to both ends of the double Venturi channel structure, which is connected to a gas-liquid two-phase flow experimental loop. A filter is installed on the liquid loop, and a check valve is installed upstream of the gas loop. The two-stage Venturi structure provides more complete energy conversion and a longer reaction time for bubble breakup. According to the results of the examples, the minimum average bubble size that can be prepared is approximately 50 μm to 400 μm (liquid flow rate 4.5 m³ / s). 3 / h≤Q sp ≤11m 3 / h, mass gas content x≤10 -4 ),like Figure 5 As shown, the statistical results of bubble size distribution prepared by using only a single-stage Venturi channel and by using both a single-stage and a two-stage Venturi channel are compared. It can be seen that using a two-stage Venturi channel can further break down the bubbles.

[0075] The design of the first-stage Venturi throat creates a stepped flow, and the flow separation process creates a local low pressure. Placing the injection port in this low-pressure area is beneficial for gas intake, effectively increasing the gas content, while avoiding liquid backflow in the pipeline system that could damage upstream equipment.

[0076] The dual Venturi channel of this invention has a two-stage Venturi structure, allowing pressure differentials to be measured separately by pressure sensors or differential pressure transmitters connected to high-pressure and low-pressure taps / pipes. This enables simultaneous flow metering of the upstream single-phase flow and the downstream gas-liquid two-phase flow. The metering installation is as follows: Figure 6 As shown, Venturi flow meters have significant advantages in relatively harsh measurement environments, such as those with small amounts of impurities, high viscosity fluids, and large temperature variations, achieving a measurement accuracy of ±1.0%.

[0077] When a project requires two-phase flow pattern identification, a differential pressure sensor can be installed between the pressure taps connected to the single-phase flow high-pressure tap 14 and the two-phase flow high-pressure tap 113. By collecting the pressure difference signal between the high-pressure single-phase flow tap and the high-pressure two-phase flow tap, characteristic parameters can be obtained through signal analysis to achieve flow pattern identification. In engineering projects, the method can be tailored to the specific flow pattern identification requirements on-site. Figure 7 As shown, a differential pressure transmitter is installed between the high-voltage single-phase flow pressure tap and the high-voltage two-phase flow pressure tap. The current / voltage signal is obtained through the data acquisition system, and then characteristic parameters such as energy spectrum or EMD are obtained through time-domain and frequency-domain analysis of the signal. The two-phase flow pattern is determined according to the characteristic parameter range of different flow patterns.

[0078] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multifunctional device for flow meter and bubble preparation based on Venturi structure, characterized in that, It includes a double Venturi channel structure (1), an annular pressure tapping tube structure, and an injection chamber (6). The double Venturi channel structure (1) includes a first-stage Venturi structure for realizing single-phase flow metering and bubble preparation, and a second-stage Venturi structure for realizing gas-liquid two-phase flow metering. The annular pressure tapping tube structure specifically includes a single-phase flow high-pressure annular pressure tapping tube (2), a single-phase flow low-pressure annular pressure tapping tube (3), a two-phase flow high-pressure annular pressure tapping tube (4), and a two-phase flow low-pressure annular pressure tapping tube (5). The first-stage Venturi structure includes a first-stage Venturi converging section module for realizing single-phase flow metering and a first-stage Venturi expanding section module for realizing bubble preparation. The first-stage Venturi tapering module includes a channel inlet section (11), a first-stage Venturi tapering section (12), a first-stage Venturi throat (13), a single-phase flow high-pressure tap (14), and a single-phase flow low-pressure tap (15); the single-phase flow high-pressure tap (14) and the single-phase flow low-pressure tap (15) are respectively connected to the single-phase flow high-pressure annular tap (2) and the single-phase flow low-pressure annular tap (3); The first-stage Venturi diffuser module includes a first-stage Venturi apical throat (16), a first-stage Venturi diffuser (17), and an air inlet (18) in the apical throat; the air inlet (18) in the apical throat is connected to the air inlet chamber (6), and the air inlet chamber (6) includes an air inlet (61) and a flow equalization chamber (62). Gas is injected through the gas injection chamber inlet (61). After passing through the gas injection chamber inlet and the flow equalization chamber, the gas enters the first-stage Venturi sudden expansion throat (16) through the gas injection hole (18) in the sudden expansion throat. Finally, the gas enters the near-wall strong turbulent region of the first-stage Venturi gradual expansion section (17) with the high-speed water flow. The gas gains turbulent kinetic energy and is fully broken up to obtain bubbles.

2. The multifunctional flow meter and bubble preparation device based on a Venturi structure according to claim 1, characterized in that: The secondary Venturi structure includes a secondary Venturi converging section module and a channel outlet section (115) for realizing gas-liquid two-phase flow metering; the secondary Venturi converging section module specifically includes a secondary Venturi connecting straight pipe section (19), a secondary Venturi converging section (110), a secondary Venturi throat (111), a secondary Venturi expanding section (112), a two-phase flow high-pressure tap (113) and a two-phase flow low-pressure tap (114); the two-phase flow high-pressure tap (113) and the two-phase flow low-pressure tap (114) are respectively connected to the two-phase flow high-pressure annular tap (4) and the two-phase flow low-pressure annular tap (5).

3. The multifunctional device for flow meter and bubble preparation based on Venturi structure according to claim 1, characterized in that: The angles of the first-order Venturi taper (12) and the second-order Venturi taper (110) are both α = 22.5°.

4. The multifunctional flow meter and bubble preparation device based on a Venturi structure according to claim 1, characterized in that: The angles of the first-order Venturi divergence (17) and the second-order Venturi divergence (112) are both β = 12.5°.

5. The multifunctional flow meter and bubble preparation device based on a Venturi structure according to claim 1, characterized in that: The inner diameters of the channel inlet section (11), the secondary Venturi connecting straight pipe section (19), and the channel outlet section (115) are the same; the inner diameter of the channel inlet section is greater than the inner diameter of the primary Venturi throat, which is greater than the inner diameter of the primary Venturi throat.

6. The multifunctional flow meter and bubble preparation device based on a Venturi structure according to claim 1, characterized in that: When single-phase flow metering is implemented, a differential pressure transmitter is installed between the single-phase high-pressure annular pressure tap (2) and the single-phase low-pressure annular pressure tap (3) to measure the pressure difference and determine the single-phase flow rate. The single-phase flow metering formula is as follows: ； In the formula, W sp For single-phase mass flow rate, ψ The coefficient of thermal expansion is the first-order Venturi coefficient. C d This is the first-order Venturi flow coefficient. A The cross-sectional area of ​​the flow path is... β It is a first-order Venturi throat diameter ratio. ΔP sp This represents the pressure difference measured between the single-phase high-pressure annular pressure tap and the single-phase low-pressure annular pressure tap. ρ sp The density is the density of the liquid medium.

7. The multifunctional device for flow meter and bubble preparation based on Venturi structure according to claim 1, characterized in that: When measuring the flow rate of a gas-liquid two-phase flow, a differential pressure transmitter is installed between the high-pressure annular pressure tap (4) and the low-pressure annular pressure tap (5) of the two-phase flow. The flow rate of the two-phase flow can be determined by measuring the pressure difference, as follows: Assuming the gas phase mass flow rate is as follows when the entire gas phase flows through the Venturi tube: ； In the formula, W g This refers to the gas phase mass flow rate. ΔP g For the pressure drop of the entire gas phase flow, ρ g Density of the gaseous medium; Assume the liquid mass flow rate is as follows when the entire liquid phase flows through the Venturi tube: ； In the formula, W l This is the liquid phase mass flow rate. ΔP l For the pressure drop of the entire liquid phase flow, ρ l The density of the liquid medium; Therefore, when the gas-liquid two-phase flow passes through the Venturi tube, the mass flow rates of the gas phase and the liquid phase are respectively: ； ； In the formula, A g This refers to the cross-sectional area of ​​the gas phase in a gas-liquid two-phase flow. A l This refers to the cross-sectional area of ​​the liquid phase in a gas-liquid two-phase flow. ΔP TP The pressure difference between the gas and liquid phases measured by the high-pressure annular pressure tap and the low-pressure annular pressure tap of the two-phase flow is considered, along with the flow area at the throat of the Venturi tube. A = A g + A l From this, we can obtain the pressure drop relationship for the ideal gas-liquid two-phase flow: ； Because actual gas-liquid two-phase flows have slip velocity and density differences, the actual pressure drop is greater than the two-phase flow pressure drop predicted by the above formula. Therefore, a correction factor is introduced. θ ( θ > 1) Correct the fit to the actual flow conditions. The calculation formula is as follows: ； Based on the measured relationship between actual flow rate and two-phase flow pressure drop, the following was obtained through fitting: θ By combining the measured pressure drop of the two-phase flow, the actual mass flow rate of the two-phase flow can be obtained.

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