A bidirectional flow venturi flowmeter

Abstract

This utility model discloses a bidirectional venturi flow meter, including a cylindrical shell and flanges at its ends. An inlet section and a throat section are sequentially arranged inside the shell. A guide vane is installed in the inlet section, and a pressure-reducing chamber is provided between the inlet section and the throat section. The minimum inner diameter of the pressure-reducing chamber is greater than the inner diameter of the throat section, and its cross-section is a streamlined pipe with smooth transitions between its front and rear ends and the inner wall of the shell. The shell also has an outlet section symmetrical to the inlet section. Pressure taps are distributed in the inlet, throat, and outlet sections, and the guide vane in the outlet section has the same flow direction as that in the inlet section. This utility model, by setting a guide vane in the inlet section to generate pre-swirling flow in the fluid, converts some axial kinetic energy into rotational kinetic energy. Combined with the streamlined design of the pressure-reducing chamber, a local low-pressure zone is formed, effectively amplifying the pressure difference effect before and after the throat section, improving the flow meter's sensitivity and upper limit of range, while avoiding pressure loss and blockage risks caused by excessive throat contraction.

Description

Technical Field

[0001] This utility model relates to the field of Venturi flow meter technology, specifically to a bidirectional flow Venturi flow meter. Background Technology

[0002] A bidirectional venturi flow meter is a flow measurement device based on Bernoulli's equation and the law of conservation of energy. It typically includes an inlet section, a throat section, and an outlet section arranged in sequence. The diameter of the throat section narrows to form a local acceleration zone to amplify the pressure difference effect. Differential pressure sensors are installed upstream and downstream of the throat section to facilitate the calculation of fluid flow rate.

[0003] However, under specific installation and operating conditions, such as a fixed pipe diameter, existing bidirectional venturi flow meters have limitations in amplifying the differential pressure effect. The differential pressure generation capability is highly dependent on the cross-sectional area ratio of the throat section to the main pipe body. Under the constraint of the same pipe diameter, the flow velocity can only be increased by reducing the throat diameter, thereby increasing the differential pressure. Excessively shrinking the throat size, while yielding a larger differential pressure signal, leads to increased permanent pressure loss and is prone to clogging when measuring fluids containing particulate matter. Conversely, using a larger throat diameter to ensure flow capacity results in an excessively weak differential pressure signal. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a structure that, in addition to addressing changes in the cross-sectional area of ​​the throat segment, increases the differential pressure effect of the Venturi flow meter, thereby improving the sensitivity of the bidirectional flow Venturi flow meter.

[0005] To achieve the above objectives, the technical solution provided by this utility model is as follows: A bidirectional venturi flow meter includes a cylindrical shell with a flange on its end face. An inlet section and a throat section are sequentially arranged inside the cylindrical shell from the end to the middle. A guide vane is disposed inside the inlet section, and a pressure-reducing cavity is provided between the guide vane and the throat section. The minimum inner diameter of the pressure-reducing cavity is greater than the inner diameter of the throat section. The cross-section of the pressure-reducing cavity is constructed as a streamlined pipe inside the cylindrical shell, with both the front and rear ends of the streamlined pipe smoothly transitioning to the inner wall of the cylindrical shell. The cylindrical shell also has an outlet section symmetrically arranged along the cross-section of the throat section and the inlet section. Pressure taps are distributed throughout the inlet, throat, and outlet sections, and the guide vane of the outlet section has the same flow direction as the guide vane of the inlet section.

[0006] As a preferred technical solution, the streamlined pipe longitudinal section of the pressure-reducing cavity is circular or elliptical, and the ratio of its radius of curvature to the inner diameter of the cylindrical shell is 2.0 to 10.0.

[0007] As a preferred technical solution, the pressure taps are evenly distributed in a circular pattern in the inlet section, throat section and outlet section, with at least four pressure taps in each section, and the axis of the pressure taps is perpendicular to the axis of the pipe.

[0008] As a preferred technical solution, the guide vane is a spiral guide vane with a spiral angle of 15° to 25°.

[0009] As a preferred technical solution, the ratio of the minimum inner diameter of the pressure-reducing cavity to the inner diameter of the throat segment is 0.8 to 1.0.

[0010] As a preferred technical solution, the ratio of the length of the throat section to the inner diameter of the cylindrical outer shell is 2.0 to 5.0.

[0011] As a preferred technical solution, the front and rear ends of the streamlined pipe have gradually narrowing and gradually expanding shapes, and the transition curves on the longitudinal section of the streamlined pipe are cubic spline curves or circular arc curves.

[0012] As a preferred technical solution, the arc curve has a tangent point parallel to the axial direction of the cylindrical shell, and the tangent of the arc curve is located inside the cylindrical shell.

[0013] As a preferred technical solution, the axial length of the guide vane accounts for 30%-60% of the length of the inlet section; the axial length of the pressure-reducing chamber accounts for 40%-70% of the length of the inlet section.

[0014] The advantages and beneficial effects of this invention are as follows: By setting a guide vane in the inlet section, the fluid is actively pre-swirled before entering the throat section, converting a portion of the fluid's axial kinetic energy into rotational kinetic energy. This allows the throat section to generate a relatively significant and easily measurable pressure difference over a wider flow range when it contracts its cross-sectional area to accelerate the fluid, thus expanding the upper limit of the flowmeter's range. Combined with the streamlined design of the pressure-reducing chamber, a smooth local low-pressure zone is formed before the throat section, further amplifying and stabilizing the differential pressure signal. Attached Figure Description

[0015] Figure 1 This is a schematic cross-sectional view of the bidirectional venturi flow meter shown in this utility model. Figure label: 1-Cylindrical outer shell, 2-Flange, 3-Inlet section, 4-Throat section, 5-Pressure-reducing chamber, 6-Streamlined pipe, 7-Outlet section, 8-Pressure tapping hole, 9-Guide plate, 10-Transition curve. Detailed Implementation

[0016] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0017] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0018] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0019] Please see Figure 1 This embodiment provides a Venturi flow meter, including a cylindrical shell 1, a flange 2 on the end face of the cylindrical shell 1, an inlet section 3 and a throat section 4 arranged sequentially from the end to the middle on the inner side of the cylindrical shell 1, a guide vane 9 is arranged inside the inlet section 3, a pressure reducing cavity 5 is left between the guide vane 9 and the throat section 4, the minimum inner diameter of the pressure reducing cavity 5 is greater than the inner diameter of the throat section 4, the cross-section of the pressure reducing cavity 5 is constructed into a streamlined pipe 6 inside the cylindrical shell 1, the front end and the rear end of the streamlined pipe 6 are smoothly transitioned with the inner wall of the cylindrical shell 1, the cylindrical shell 1 is also provided with an outlet section 7 symmetrically arranged along the cross-section of the throat section 4 and the inlet section 3; pressure taps 8 are evenly distributed in the inlet section 3, the guide vane of the outlet section 7 has the same guiding direction as the guide vane 9 of the inlet section 3. When the fluid enters from the inlet section 3, the guide vane 9 causes the fluid to generate a pre-swirling flow, converting some of the axial kinetic energy into rotational kinetic energy. The streamlined pipe 6 of the pressure-reducing chamber 5 forms a local low-pressure zone, and the throat section 4 further accelerates the fluid, thereby amplifying the pressure difference effect. The symmetrical outlet section 7 ensures measurement consistency during bidirectional flow, and the pressure tap 8 is used to detect the pressure difference in each section, improving the sensitivity and upper limit of the flow meter, while avoiding pressure loss and blockage risk caused by excessive throat contraction.

[0020] Specifically, this is based on the law of conservation of fluid mechanical energy described by Bernoulli's equation. Bernoulli's equation states that in the steady flow of an incompressible fluid, the sum of the fluid's static pressure, dynamic pressure, and potential energy is constant. In this flowmeter, the conversion of these energy forms is actively regulated. When the fluid enters inlet section 3, the guide vanes 9 generate a strong pre-swirling flow, which converts a portion of the fluid's axial kinetic energy into rotational kinetic energy. According to Bernoulli's equation, under the premise of constant total energy, the fluid's axial kinetic energy (manifested as dynamic pressure) is thus intentionally reduced, resulting in a corresponding decrease in its static pressure. Combined with the streamlined profile of the pressure-reducing chamber, this creates a localized low-pressure zone.

[0021] The fluid enters the throat section, where the cross-sectional area contracts. According to the continuity equation, the flow velocity inevitably increases, and the kinetic energy (dynamic pressure) increases. At this point, the superposition effect of energy conversion becomes apparent: because the pre-swirl effect of the inlet section 3 has already lowered the static pressure baseline of the fluid, when the fluid accelerates in the throat section 4, its static pressure will decrease from a lower baseline value. This amplifies the static pressure difference between the throat section 4 and the inlet section 3 compared to a conventional venturi tube at the same throat flow velocity. This amplified differential pressure signal is detected by a differential pressure sensor through the pressure tap, thereby achieving a more sensitive response to small flow rates and expanding the upper limit of measurable flow rates, ultimately achieving a high-sensitivity, wide-range measurement effect.

[0022] It should be noted that the pre-swirl process, combined with the streamlined profile of the pressure-reducing chamber, creates a stable local low-pressure zone upstream of the throat section. This results in an additional 15% to 30% reduction in static pressure at this location compared to the inlet static pressure of a traditional Venturi flowmeter under the same operating conditions. The specific reduction depends on the shape and cross-sectional area of ​​the guide vanes. The effective pressure difference generated by this invention before and after the throat section is 1.3 to 1.8 times greater than that of a traditional Venturi flowmeter without pre-swirl guidance design.

[0023] To optimize the streamlined design of the pressure-reducing chamber 5 to reduce local resistance and stabilize the low-pressure area, the technical solution provided in this embodiment is that the longitudinal section of the streamlined pipe 6 of the pressure-reducing chamber 5 is circular or elliptical, and the ratio of its radius of curvature to the inner diameter of the cylindrical outer shell 1 is 2.0 to 10.0. The smooth contour of the streamlined pipe 6 guides the fluid to transition smoothly, reducing eddies and energy loss; the curvature ratio ensures that flow separation is minimized, enhancing the formation and stability of the low-pressure area.

[0024] To ensure that the pressure taps 8 can uniformly collect pressure signals and avoid local flow interference, the technical solution provided in this embodiment is that the pressure taps 8 are evenly distributed circumferentially in the inlet section 3, throat section 4, and outlet section 7, with at least four pressure taps 8 in each section, and the axis of the pressure taps 8 is perpendicular to the pipe axis. The circumferential distribution of the pressure taps 8 covers the entire flow field, and the perpendicular axis design reduces fluid impact errors; multiple pressure taps 8 compensate for flow asymmetry through average pressure values, providing more accurate differential pressure data.

[0025] To effectively generate pre-swirling flow and control energy conversion efficiency through the guide vane 9, the technical solution provided in this embodiment is that the guide vane 9 is a spiral guide vane with a spiral angle of 15° to 25°. The spiral guide vane 9 guides the fluid to rotate in the inlet section 3, and the spiral angle range optimizes the conversion of axial kinetic energy into rotational kinetic energy; the pre-swirling flow reduces the axial velocity component before entering the throat section 4, enhances the throat acceleration effect, thereby amplifying the pressure difference and expanding the flow range.

[0026] To balance the dimensional relationship between the pressure-reducing chamber 5 and the throat segment 4 to optimize differential pressure amplification and flow resistance, the technical solution provided in this embodiment is that the ratio of the minimum inner diameter of the pressure-reducing chamber 5 to the inner diameter of the throat segment 4 is 0.8 to 1.0. This ratio ensures that the pressure-reducing chamber 5 does not contract excessively, avoiding additional pressure loss; the minimum inner diameter is close to or equal to the inner diameter of the throat segment 4, allowing the fluid to be initially accelerated in the pressure-reducing chamber 5, cooperating with the throat segment 4 to form a continuous low-pressure gradient and improve differential pressure sensitivity.

[0027] To ensure that the throat section 4 has sufficient length to stabilize the flow and fully develop the acceleration effect, the technical solution provided in this embodiment is that the ratio of the length of the throat section 4 to the inner diameter of the cylindrical outer shell 1 is 2.0 to 5.0. The extended design of the throat section 4 provides sufficient space for fluid acceleration and stabilization, reducing end effects; the length ratio optimizes flow continuity and prevents premature flow separation.

[0028] To achieve a smooth transition in the streamlined pipe 6 and minimize flow resistance and energy loss, the technical solution provided in this embodiment is that both the front and rear ends of the streamlined pipe 6 have tapered and expanded shapes, respectively. On the longitudinal section of the streamlined pipe 6, the transition curve 10 is a cubic spline curve or a circular arc curve. The tapered and expanded shapes guide the fluid to gradually accelerate and decelerate, and the curvature of the transition curve 10 is continuous.

[0029] To optimize the connection between the transition curve 10 of the streamlined pipe 6 and the inner wall of the cylindrical shell 1, the technical solution provided in this embodiment is that the arc curve has a tangent point parallel to the axial direction of the cylindrical shell, and the tangent of the arc curve is located on the inner side of the cylindrical shell 1. The parallel tangent design ensures that the fluid flows without abrupt changes in the transition zone, and the alignment of the tangents on the inner surface reduces boundary layer interference; this structure improves the continuity of the flow and stabilizes the differential pressure signal.

[0030] Specifically, the tangent point is the midpoint of the circular arc curve.

[0031] To control the influence range of the guide vane 9 in the inlet section 3 and optimize the generation of pre-swirling flow, the technical solution provided in this embodiment is that the axial length of the guide vane 9 accounts for 30%-60% of the length of the inlet section 3. The length ratio of the guide vane 9 ensures a sufficiently long guiding path to generate a stable pre-swirling flow, while avoiding excessive length that would cause additional resistance.

[0032] To rationally allocate the space of the pressure-reducing chamber 5 within the inlet section 3 to coordinate the formation of the low-pressure zone and the continuity of flow, the technical solution provided in this embodiment is that the axial length of the pressure-reducing chamber 5 accounts for 40%-70% of the length of the inlet section 3. The length ratio of the pressure-reducing chamber 5 provides sufficient area for streamlined acceleration and low-pressure development.

[0033] The working principle of this invention is as follows: When fluid enters the flow meter from the inlet section 3, the guide vane 9 guides the fluid to generate a pre-swirling flow, converting some of the axial kinetic energy into rotational kinetic energy and reducing the axial velocity component of the fluid. The fluid then enters the pressure-reducing chamber 5, where the smooth transition of the streamlined pipe 6 creates a local low-pressure zone, further reducing pressure energy. In the throat section 4, the fluid cross-sectional area contracts, leading to acceleration. The pre-swirling flow and the low-pressure zone amplify the pressure difference before and after the throat section 4. The pressure tap 8 detects pressure at the inlet section 3, throat section 4, and outlet section 7, and the flow rate is calculated by a differential pressure sensor. The symmetrical outlet section 7 ensures consistent measurement during bidirectional flow, and the guide vane 9 maintains stable flow by maintaining a consistent direction. This invention enhances the differential pressure effect through pre-swirling flow and the streamlined pressure-reducing chamber, improving sensitivity and the upper limit of the flow range, while avoiding pressure loss and blockage problems caused by excessive throat contraction.

[0034] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A bidirectional venturi flow meter, characterized in that, The system includes a cylindrical outer shell (1), with a flange (2) on its end face. An inlet section (3) and a throat section (4) are sequentially arranged on the inner side of the cylindrical outer shell (1) from the end to the middle. A guide vane (9) is provided inside the inlet section (3). A pressure-reducing cavity (5) is provided between the guide vane (9) and the throat section (4). The minimum inner diameter of the pressure-reducing cavity (5) is less than or equal to the inner diameter of the throat section (4). The cross-section of the pressure-reducing cavity (5) is configured to resemble that of the cylindrical outer shell. 1) The streamlined pipe (6) inside, the front end and the rear end of the streamlined pipe (6) are smoothly transitioned to the inner wall of the cylindrical shell (1), the cylindrical shell (1) is also provided with an outlet section (7) symmetrically arranged along the cross section of the throat section (4) and the inlet section (3); the inlet section (3), the throat section (4) and the outlet section (7) are all provided with pressure tapping holes (8), and the guide vane of the outlet section (7) and the guide vane (9) of the inlet section (3) have the same guiding direction.

2. The bidirectional venturi flow meter according to claim 1, characterized in that, The streamlined pipe (6) of the pressure-reducing cavity (5) has a longitudinal section that is circular or elliptical, and the ratio of its radius of curvature to the inner diameter of the cylindrical shell (1) is 2.0 to 10.

0.

3. The bidirectional venturi flow meter according to claim 1, characterized in that, The pressure taps (8) are evenly distributed in a circle in the inlet section (3), throat section (4) and outlet section (7), with at least four pressure taps (8) in each section, and the axis of the pressure taps (8) is perpendicular to the axis of the pipe.

4. The bidirectional venturi flow meter according to claim 1, characterized in that, The guide vane (9) is a spiral guide vane with a spiral angle of 15° to 25°.

5. The bidirectional venturi flow meter according to claim 1, characterized in that, The ratio of the minimum inner diameter of the pressure-reducing chamber (5) to the inner diameter of the throat segment (4) is 0.8 to 1.

0.

6. The bidirectional venturi flow meter according to claim 1, characterized in that, The length of the throat segment (4) is 2.0 to 5.0 of the inner diameter of the cylindrical shell (1).

7. The bidirectional venturi flow meter according to claim 1, characterized in that, The streamlined pipe (6) has a tapered shape at both the front and rear ends. The transition curve (10) on the longitudinal section of the streamlined pipe (6) is a cubic spline curve or a circular arc curve.

8. The bidirectional venturi flow meter according to claim 7, characterized in that, The arc curve has a tangent point parallel to the axial direction of the cylindrical shell (1), and the tangent of the arc curve is located inside the cylindrical shell (1).

9. The bidirectional venturi flow meter according to claim 1, characterized in that, The axial length of the guide vane (9) accounts for 30%-60% of the length of the inlet section (3).

10. The bidirectional venturi flow meter according to claim 1, characterized in that, The axial length of the pressure-reducing chamber (5) accounts for 40%-70% of the length of the inlet section (3).

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