Magnetic fluid-based pipe water flow speed measuring device and speed measuring method thereof

Abstract

The application provides a kind of pipeline water flow speed measuring device based on magnetic fluid and its speed measuring method, it is related to pipeline fluid speed measuring field, it includes pipeline, at least two speed measuring points being arranged along the axial direction of pipeline and signal acquisition unit;Each speed measuring point includes trigger component, transmission component and sealed signal cavity, trigger component generates trigger displacement under the action of water flow, transmission component transmits trigger displacement, sealed signal cavity is arranged on the outside of pipeline and is isolated from the fluid in the inside of pipeline, magnetic fluid medium and signal trigger component are provided in sealed signal cavity, and signal acquisition unit calculates the flow velocity of water flow in pipeline according to the time difference of at least two speed measuring points. The application can adapt to non-conductive or impurity-containing water flow, improve the stability and environmental adaptability of speed measurement.

Description

Technical Field

[0001] This application relates to the field of pipeline fluid velocity measurement technology, and in particular to a pipeline water flow velocity measurement device and method based on magnetofluid. Background Technology

[0002] Pipeline flow velocity measurement is an important means of obtaining fluid velocity and flow parameters within pipelines, and it is widely used in water supply and drainage systems, industrial circulating water systems, equipment cooling circuits, and various liquid transport pipelines. By measuring the water flow velocity within pipelines in real time, basic data can be provided for pump and valve regulation, operating condition monitoring, flow control, and fault early warning, thereby ensuring the stability and safety of pipeline system operation.

[0003] Currently, common pipeline flow velocity measurement devices mainly include electromagnetic velocity measuring devices, turbine velocity measuring devices, and other velocity measuring devices that rely on electronic sensing elements. Electromagnetic velocity measuring devices typically require the measured fluid to have a certain degree of conductivity. When the conductivity of the measured fluid is insufficient or the medium composition is complex, the accuracy of the velocity measurement can be easily affected. Furthermore, the electrodes are in long-term contact with the fluid, making them susceptible to contamination, scaling, or corrosion, which can lead to signal drift or even failure. Turbine velocity measuring devices usually rely on mechanical rotating parts such as impellers and shafts to achieve velocity measurement. When the fluid contains silt, particulate impurities, or suspended solids, problems such as jamming, wear, and insensitive rotation can easily occur, affecting measurement accuracy and increasing maintenance frequency and operating costs. While some electronic velocity measuring solutions can achieve non-mechanical counting or electrical signal output, they often require continuous power supply, and the reliability of contacts, wire connections, and electronic sensing elements is still easily affected in humid, submerged, or long-term underwater environments.

[0004] Therefore, the existing technology has at least the following shortcomings: on the one hand, some speed measurement schemes have high requirements for the conductivity, cleanliness or operating environment of the fluid being measured, which limits their applicability; on the other hand, the mechanical rotating structure, direct liquid-contact electrodes or electronic components that are exposed to a humid environment for a long time in the existing devices are prone to wear, contamination, jamming or failure, making it difficult to meet the needs of structural reliability, measurement stability and rapid on-site measurement.

[0005] Therefore, there is an urgent need to provide a pipeline water flow velocity measuring device that can adapt to non-conductive or impurity-containing water flow, effectively isolate the signal triggering part from the fluid in the pipeline, and facilitate stable velocity measurement, so as to overcome the above-mentioned problems existing in the prior art. Summary of the Invention

[0006] To address the aforementioned technical problems, this application provides a pipeline water flow velocity measuring device based on magnetohydrodynamics.

[0007] The pipeline water flow velocity measuring device based on magnetohydrodynamics provided in this application adopts the following technical solution: A magnetohydrodynamic (MHD) pipe flow velocity measurement device includes: pipeline; At least two speed measuring points are set at intervals along the axial direction of the pipeline; Each of the speed measuring points includes a triggering component, a transmission component, and a sealed signal cavity; The triggering component is disposed on the pipe and is used to generate a trigger displacement under the action of water flow; The transmission component is connected to the trigger component and is used to transmit the trigger displacement; The sealed signal cavity is located outside the pipe and is isolated from the fluid inside the pipe. The sealed signal cavity is provided with a magnetic fluid medium and a signal triggering component. The signal triggering component is connected to the transmission component and can make the magnetic fluid medium conduct and output a conduction signal under the action of the trigger displacement. The signal acquisition unit is connected to each of the speed measuring points and is used to acquire the conduction signal of each speed measuring point and calculate the water flow velocity in the pipeline based on the time difference of the conduction signals of at least two speed measuring points.

[0008] Furthermore, the triggering component includes a flow-blocking element installed on the inner wall of the pipe, which oscillates or deflects under the impact of water flow.

[0009] Furthermore, the triggering component also includes a mounting groove, a hinge shaft, and a reset component. The flow obstruction component is rotatably mounted in the mounting groove via the hinge shaft, and the reset component is used to drive the flow obstruction component to reset after the water flow disappears.

[0010] Furthermore, the transmission assembly includes a rigid connecting rod connecting the triggering assembly and the signal triggering assembly.

[0011] Furthermore, the signal triggering component includes a first electrode and a second electrode disposed opposite to each other, wherein at least one of them is connected to the transmission component and is capable of moving with the trigger displacement to change the relative distance between the first electrode and the second electrode, thereby enabling the magnetofluid medium to conduct.

[0012] Furthermore, one of the first electrode and the second electrode is fixedly disposed, while the other moves with the transmission assembly.

[0013] Furthermore, a dynamic sealing structure is provided at the through connection between the transmission component and the sealed signal cavity.

[0014] Furthermore, the dynamic sealing structure includes a sealing ring and a stepped slip ring.

[0015] Furthermore, each of the speed measuring points is arranged coaxially along the pipeline axis, and the distance between adjacent speed measuring points is a preset value.

[0016] This application also provides a pipeline water flow velocity measurement method based on magnetohydrodynamics, comprising the following steps: S1. Pre-calibrate the distance between two adjacent speed measuring points as a fixed value L; S2, causing the water flow to sequentially trigger at least two velocity measurement points to output conduction signals; S3. Collect the activation signal trigger time of the at least two speed measuring points and obtain the time interval t; S4. Calculate the water flow velocity in the pipe based on the spacing L and the time interval t.

[0017] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention, by setting up a triggering component, a transmission component, and a sealed signal cavity isolated from the fluid inside the pipeline, enables the mechanical displacement formed by the water flow to be transmitted to the sealed signal cavity and trigger the magnetic fluid medium to generate a conduction signal. The water flow velocity is then calculated by combining the conduction signal time difference of at least two velocity measuring points. This solves the problems of insufficient coordination between the velocity measuring structure and the signal output structure in existing pipeline velocity measuring devices, and the difficulty in balancing sealed isolation and stable velocity measurement. It achieves the effects of stable triggering, reliable signal output, and accurate velocity measurement inside the pipeline. 2. This invention solves the problem of traditional electronic contacts being prone to failure in humid or immersive environments by placing the magnetic fluid medium, input electrode, and sensing electrode inside a sealed signal cavity, and by changing the relative distance between the sensing electrode and the input electrode under the drive of the transmission component, so as to utilize the magnetic fluid medium to form a conduction signal in the critical conduction state. This achieves the effect of effectively isolating the signal triggering part from the measured water flow, improving the reliability of signal triggering and environmental adaptability. 3. This invention solves the problem of precision rotating parts in traditional turbine speed measuring devices being easily affected by impurity particles and causing jamming and wear by setting a trigger component that is impacted by water flow inside the detection pipe and using a transmission component to transmit the trigger displacement to the sealed signal cavity outside the pipe. This achieves the effect of being suitable for water flow containing impurities, reducing mechanical wear and reducing maintenance requirements. 4. This invention uses a dual-point or multi-point time difference method for velocity measurement and can process multiple sets of velocity measurement results. This solves the problems of single-point velocity measurement being easily affected by local disturbances and insufficient stability of velocity measurement results, thereby improving the accuracy of pipeline water flow average velocity measurement and the reliability of velocity measurement results. 5. This invention solves the problem of traditional electromagnetic speed measuring devices having high requirements for the conductivity of the measured medium and limited applicability by making the generation of the speed measuring signal dependent on the conduction of the magnetohydrodynamic medium in the sealed signal cavity, rather than on the conductivity of the measured water flow itself. This achieves the effect of being adaptable to water flows of different properties and reducing the requirements for pretreatment of the measured medium. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application.

[0020] Figure 2 This is a cross-sectional view of an embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the trigger component and transmission component according to an embodiment of this application.

[0022] Reference numerals in the attached drawings: 1. Pipeline; 2. Sealed and insulated cavity; 3. First electrode; 4. Second electrode; 5. Magnetofluid medium; 6. Limiting plate; 7. Sealing ring; 8. Stepped slip ring; 9. Guide post; 10. Baffle plate; 11. Reset torsion spring; 12. Rigid connecting rod; 13. Limiting groove. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] Specifically, such as Figures 1 to 3As shown, this embodiment discloses a pipeline water flow velocity measuring device based on magnetohydrodynamics, which includes a pipeline, at least two velocity measuring points, and a signal acquisition unit connected to each velocity measuring point. The pipeline is a hollow cylinder, with a flow channel formed inside for water flow. At least two velocity measuring points are spaced apart along the axial direction of the pipeline, preferably arranged sequentially along the same axis, with a preset distance between adjacent velocity measuring points. The signal acquisition unit is used to collect the conduction signals output by each velocity measuring point and calculate the water flow velocity in the pipeline based on the trigger time difference of the conduction signals of at least two velocity measuring points. With this setup, the propagation process of water flow along the pipeline direction can be converted into a time-series electrical signal, and then the velocity can be measured using the time difference method.

[0025] Furthermore, each speed measuring point includes a triggering component, a transmission component, and a sealed signal cavity. The triggering component is located in the flow-receiving area inside the pipe and is used to generate a trigger displacement under the impact of water flow. The transmission component is connected to the triggering component and is used to transmit the trigger displacement from inside the pipe to outside the pipe. The sealed signal cavity is fixed on the outside of the pipe, and it contains a magnetohydrodynamic medium and a signal triggering component. The sealed signal cavity is isolated from the water flow inside the pipe. Thus, the water flow action point and the electrical signal generation point are located on the inside and outside of the pipe, respectively, which can ensure trigger sensitivity and improve the sealing and environmental adaptability of the signal triggering part.

[0026] Specifically, the triggering components include a mounting groove, a baffle plate, a hinge shaft, and a reset element, preferably a reset torsion spring. The mounting groove is not a recess directly formed in the inner wall of the pipe, but rather an independent groove component fixedly installed on the inner wall of the pipe. Preferably, the mounting groove is generally a right-angled triangle, with one right-angled side flush against and fixedly connected to the inner wall of the pipe, and the other side facing the inner cavity of the pipe, thus forming a support space for installing the baffle plate, hinge shaft, and reset torsion spring. This structure provides a stable mounting base for the baffle plate and also helps to reduce the space occupied by the groove in the flow channel while ensuring strength.

[0027] Furthermore, the baffle plate is a sheet-like component, preferably a plate-like or arc-shaped structure. To reduce additional obstruction to the flow channel, the baffle plate is preferably fitted to the local contour of the inner wall of the pipe. One edge of the baffle plate is rotatably mounted on the mounting groove via a hinge shaft, while the other edge forms a free end subjected to water flow impact. A return torsion spring is sleeved on the outer periphery of the hinge shaft and forms an elastic relationship with both the baffle plate and the mounting groove, so as to drive the baffle plate back to its initial position after the water flow disappears. Thus, the baffle plate can swing around the hinge shaft under the impact of water flow, and automatically swing back to its original position under the action of the return torsion spring after the water flow is removed.

[0028] Preferably, the closing direction of the baffle plate is consistent with the water flow direction. That is, in the initial state, the baffle plate is preferably placed against the open side of the mounting groove or close to the inner wall of the pipe; when the water flows in the preset direction, the water flow impacts the free end of the baffle plate, causing the baffle plate to swing upward around the hinge axis. With this arrangement, the baffle plate has less impact on fluid passage in the closed state, and the starting resistance is lower, which is more conducive to triggering response under low flow velocity conditions. Thus, it can not only improve the velocity measurement sensitivity, but also reduce the disturbance to the original flow state in the pipe.

[0029] To transmit the oscillating motion of the baffle plate to the outside of the pipe, a rigid connecting rod is used in the transmission assembly. The rigid connecting rod is a slender rod-shaped component, preferably a cylindrical rod, but it can also be a square rod or other long structure with sufficient axial stiffness. In this embodiment, the rigid connecting rod is preferably a straight rod structure, with its inner end connected to the baffle plate and its outer end passing through the sealed signal cavity and extending into the sealed insulating cavity. The rigid connecting rod and the baffle plate can be fixedly connected, snap-fitted, or plugged in; in this embodiment, a fixed connection is preferred to ensure that the rigid connecting rod can move synchronously and stably in a predetermined direction when the baffle plate moves. With this configuration, the mechanical displacement caused by the water flow inside the pipe can be reliably transmitted to the outside of the pipe.

[0030] Furthermore, to limit the sway of the rigid connecting rod during movement, a guide post is preferably installed within the sealed insulating cavity. The guide post is cylindrical in shape, extends along the direction of movement of the rigid connecting rod, and forms a guiding engagement with it. Under the constraint of the guide post, the rigid connecting rod undergoes an approximately linear up-and-down movement, thus making the subsequent approach of the second electrode to the first electrode smoother. This improves the consistency of the relative spacing changes between the electrodes, thereby enhancing the stability and repeatability of the conduction signal triggering.

[0031] The sealed signal cavity includes a sealed insulating cavity, a magnetohydrodynamic medium, and a signal triggering component located within the sealed insulating cavity. The sealed insulating cavity is a hollow, closed shell, which can be cylindrical, box-shaped, or other insulating structures capable of forming a sealed inner cavity. In this embodiment, it is preferably fixed to the outer wall of the pipe. This design prevents water flow from directly entering the sealed insulating cavity, thus isolating silt, particulate impurities, scale, and corrosive media from the signal triggering area. This reduces the risk of contamination and wear, and improves the reliability of the electrical signal output.

[0032] Specifically, the signal triggering component includes a first electrode and a second electrode, which are arranged opposite to each other, with at least one electrode capable of moving with the trigger displacement. In this embodiment, the first electrode is fixedly installed in a sealed insulating cavity and electrically connected to an external signal acquisition unit, maintaining its position unchanged; the second electrode is fixed to the end of a rigid connecting rod and can move synchronously with the rigid connecting rod. Preferably, the first electrode is located above the second electrode, and the two are arranged vertically opposite each other along the movement direction of the rigid connecting rod, maintaining a preset gap in the initial state. With this arrangement, once the baffle plate is lifted by the water flow, the second electrode can move closer to the first electrode under the action of the rigid connecting rod, thereby changing the relative distance between the two electrodes.

[0033] Furthermore, a magnetic fluid medium fills the sealed, insulated cavity and is located between the first and second electrodes. The magnetic fluid medium is preferably a solid-liquid mixed colloidal solution composed of magnetic nanoparticles, a base liquid, and a surfactant. Initially, the magnetic fluid medium is not subjected to compression, and its internal particle components are dispersed. Preferably, the initial preset gap between the first and second electrodes is 5 mm to 8 mm to balance trigger sensitivity and reset reliability. When the second electrode moves towards the first electrode under the action of the rigid connecting rod, reducing the gap between them to a critical state for conduction, a stable electric field is formed between the two electrodes. Under the action of this electric field, the particle components in the magnetic fluid medium form a continuous conductive path, thereby enabling electrical signal conduction between the first and second electrodes. With this configuration, the formation of the speed measurement signal does not depend on whether the water flow in the pipe itself is conductive, but rather on the change in the conductivity state of the magnetic fluid medium within the sealed cavity.

[0034] The signal generation principle within the sealed, insulated cavity can be understood as follows: In the initial state, the first and second electrodes maintain an initial preset gap, and the magnetofluid medium between them is in a non-conductive state. When the baffle plate oscillates under the impact of water flow and moves the second electrode toward the first electrode via a rigid connecting rod, the relative distance between the first and second electrodes gradually decreases. When this relative distance decreases to the critical state of conduction, a stable electric field is formed between the two electrodes. Under the action of the electric field, the particulate components in the magnetofluid medium form a continuous conductive path along the two electrodes, thereby enabling conduction between the first and second electrodes and outputting a conduction signal. Thus, the mechanical displacement caused by water flow within the pipe can be converted into a change in electrical signal within the sealed signal cavity.

[0035] To define the termination position after the second electrode returns to its original position, a limiting plate is preferably provided within the sealed insulating cavity. The limiting plate can be a sheet-like, block-like, or ring-shaped limiting component; in this embodiment, it is preferably located below the reset path of the second electrode. When the rigid connecting rod returns downwards, the second electrode stops moving downwards under the action of the limiting plate, thereby restoring the initial preset gap between it and the first electrode. As a result, the conduction path in the magnetohydrodynamic medium disappears, the conduction signal between the electrodes terminates, and preparation is made for the next speed measurement.

[0036] Furthermore, a dynamic sealing structure is provided at the through-connection between the rigid connecting rod and the sealed signal cavity. The dynamic sealing structure includes a sealing ring and a stepped slip ring. The sealing ring is an overall annular elastic element, which can adopt a circular cross-section or other cross-sectional form that can provide preload; in this embodiment, the sealing ring is preferably an O-ring. The stepped slip ring is an overall annular sliding element, whose inner hole mates with the outer surface of the rigid connecting rod, and whose outer circumference forms a stepped structure adapted to the mounting hole. Preferably, the sealing ring is made of fluororubber, and the stepped slip ring is made of polytetrafluoroethylene mixed with copper powder. In the unpressurized state, the elastic preload of the sealing ring presses the stepped slip ring against the outer surface of the rigid connecting rod to form an initial sealing surface; when the second electrode moves up and down with the rigid connecting rod, a small positive pressure is generated inside the sealed insulating cavity, which further pushes the stepped slip ring to press against the rigid connecting rod, thereby forming a pressure self-sealing effect. With this setting, the needs of the reciprocating motion of the rigid connecting rod can be met, and the leakage of the magnetohydrodynamic medium from the through-connection can be suppressed.

[0037] Based on the above structure, this embodiment also discloses a pipeline water flow velocity measurement method based on magnetohydrodynamics. This method is applied to the above-mentioned velocity measurement device and specifically includes the following steps: S1. Pre-calibrate the distance between two adjacent speed measurement points as a fixed value L.

[0038] Specifically, after the device is installed, the positions of two adjacent velocity measuring points arranged sequentially along the pipeline axis are first determined. Then, the straight-line distance between the two velocity measuring points is calibrated, and this distance is used as a fixed value L for subsequent velocity calculations. When there are three or more velocity measuring points, the distance between each adjacent velocity measuring point can also be calibrated separately to facilitate subsequent group calculations of local flow velocities. This setup provides a definite distance measurement basis for time difference velocity measurement.

[0039] S2, causing the water flow to sequentially trigger at least two velocity measurement points to output conduction signals.

[0040] During testing, water flows axially along the pipe, passing sequentially through upstream and downstream velocity measuring points. When the water flows through the upstream velocity measuring point, the baffle plate oscillates around its hinge axis under the impact of the water flow. The return torsion spring undergoes elastic deformation and stores energy, and the rigid connecting rod displaces with the movement of the baffle plate, causing the second electrode to move closer to the first electrode under the guidance of the guide column. When the relative distance between the two electrodes decreases to the critical state of conduction, the magnetohydrodynamic medium in the sealed insulating cavity becomes conductive, thus causing the velocity measuring point to output the first set of conduction signals. Subsequently, the water continues to flow along the pipe and acts on the downstream velocity measuring point, which repeats the above process and outputs the second set of conduction signals. Thus, the process of water flow propagating along the pipe can be converted into a time-series signal output sequentially by multiple velocity measuring points.

[0041] S3. Collect the trigger time of the conduction signal at at least two speed measurement points and obtain the time interval t.

[0042] Specifically, the signal acquisition unit is connected to each speed measurement point and records the corresponding trigger time when each speed measurement point outputs a conduction signal. For two adjacent speed measurement points, the signal acquisition unit subtracts the trigger time of the previous speed measurement point from the trigger time of the conduction signal of the latter speed measurement point to obtain the time interval t between them. When multiple speed measurement points are arranged, the signal acquisition unit can also record the trigger times of multiple sets of adjacent speed measurement points and obtain the corresponding time intervals for each. This setting can provide time parameters for subsequent flow velocity calculations.

[0043] S4. Calculate the water flow velocity in the pipe based on the spacing L and the time interval t.

[0044] Specifically, the signal acquisition unit calculates the average flow velocity between two adjacent velocity measurement points based on the time difference formula v=L / t. Given the pipe's cross-sectional area, the flow rate can be further calculated. When there are multiple velocity measurement points, adjacent points can be grouped pairwise, their flow velocities calculated separately, and then the arithmetic mean of multiple velocity data sets is performed to obtain a more stable average flow velocity. This setup reduces errors caused by local disturbances at a single velocity measurement point, improving measurement accuracy and result stability.

[0045] Furthermore, after completing step S4, when the water flow in the pipeline stops or decreases to a level insufficient to maintain the triggering state, the flow-blocking plates at each speed measuring point lose the impact of the water flow. The reset torsion spring releases its stored force and drives the flow-blocking plate to swing back. The rigid connecting rod then moves in the opposite direction. The second electrode returns to its initial position under the action of the limiting plate, and the initial preset gap is re-established between the first and second electrodes. The magnetofluid medium returns from a conductive state to a disconnected state, thereby enabling each speed measuring point to automatically reset after one speed measurement, preparing for the next speed measurement. Thus, this embodiment can not only achieve single speed measurement but also meet the needs of continuous and repeated speed measurement.

[0046] In alternative implementations, different base fluid formulations of magnetohydrodynamic media can be selected for different operating environments at varying temperatures to maintain suitable rheological properties and conduction signal response characteristics. For low-flow-rate conditions, the spring force of the reset torsion spring can be appropriately reduced, and the initial preset gap between the first and second electrodes can be correspondingly narrowed to lower the starting resistance of the baffle plate and the signal triggering threshold, ensuring that the water flow at lower velocities can still push against the baffle plate and trigger the conduction signal. With these settings, both the device and method can adapt to the velocity measurement requirements of different flow rate ranges and operating conditions.

[0047] In summary, this embodiment achieves effective synergy between the triggering structure, signal output structure, and speed measurement logic by installing a flow-impact-resistant baffle plate inside the pipe and using a rigid connecting rod to transmit the trigger displacement to a sealed, insulated cavity isolated from the fluid inside the pipe. This allows the magnetohydrodynamic medium to form a controllable conductive signal between the first and second electrodes. Combined with the dual- or multi-point time difference method to calculate the water flow velocity, this approach reduces the risk of jamming and wear in traditional turbine-type speed measurement structures within water containing impurities, avoids the dependence of traditional electromagnetic speed measurement on the conductivity of the measured medium, and improves the overall environmental adaptability and speed measurement stability.

[0048] 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 foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A magnetic fluid based pipe flow velocity measurement device, characterized in that, include: pipeline; At least two speed measuring points are set at intervals along the axial direction of the pipeline; Each of the speed measuring points includes a triggering component, a transmission component, and a sealed signal cavity; The triggering component is disposed on the pipe and is used to generate a trigger displacement under the action of water flow; The transmission component is connected to the trigger component and is used to transmit the trigger displacement; The sealed signal cavity is located outside the pipe and is isolated from the fluid inside the pipe. The sealed signal cavity is provided with a magnetic fluid medium and a signal triggering component. The signal triggering component is connected to the transmission component and can make the magnetic fluid medium conduct and output a conduction signal under the action of the trigger displacement. The signal acquisition unit is connected to each of the speed measuring points and is used to acquire the conduction signals of each speed measuring point and calculate the water flow velocity in the pipeline based on the time difference of the conduction signals of at least two speed measuring points.

2. The magnetofluid-based pipe flow-velocity-measuring device according to claim 1, characterized by The triggering component includes a flow-blocking element installed on the inner wall of the pipe, which oscillates or deflects under the impact of water flow.

3. The pipeline water flow velocity measuring device based on magnetohydrodynamics according to claim 2, characterized in that, The triggering component further includes a mounting groove, a hinge shaft, and a reset component. The flow obstruction component is rotatably mounted in the mounting groove via the hinge shaft, and the reset component is used to drive the flow obstruction component to reset after the water flow disappears.

4. The pipeline water flow velocity measuring device based on magnetohydrodynamics according to claim 1, characterized in that, The transmission assembly includes a rigid connecting rod connecting the triggering assembly and the signal triggering assembly.

5. The pipeline water flow velocity measuring device based on magnetohydrodynamics according to claim 1, characterized in that, The signal triggering component includes a first electrode and a second electrode disposed opposite to each other, wherein at least one of them is connected to the transmission component and is movable with the trigger displacement to change the relative distance between the first electrode and the second electrode, thereby enabling the magnetofluid medium to conduct.

6. The pipeline water flow velocity measuring device based on magnetohydrodynamics according to claim 5, characterized in that, One of the first electrode and the second electrode is fixedly disposed, while the other moves with the transmission assembly.

7. The pipeline water flow velocity measuring device based on magnetohydrodynamics according to claim 1, characterized in that, A dynamic sealing structure is provided at the through connection between the transmission component and the sealed signal cavity.

8. The pipeline water flow velocity measuring device based on magnetohydrodynamics according to claim 7, characterized in that, The dynamic sealing structure includes a sealing ring and a stepped slip ring.

9. The pipeline water flow velocity measuring device based on magnetohydrodynamics according to claim 1, characterized in that, Each of the speed measuring points is arranged coaxially along the pipeline axis, and the distance between adjacent speed measuring points is a preset value.

10. A method for measuring the velocity of water flow in a pipeline based on magnetohydrodynamics, characterized in that, The pipeline water flow velocity measuring device based on magnetohydrodynamics as described in any one of claims 1-9 includes the following steps: S1. Pre-calibrate the distance between two adjacent speed measurement points as a fixed value L; S2. Cause the water flow to sequentially trigger at least two velocity measurement points to output conduction signals; S3. Collect the activation signal trigger time of the at least two speed measuring points and obtain the time interval t; S4. Calculate the water flow velocity in the pipe based on the spacing L and the time interval t.

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