Laser Doppler open channel flow measuring device, flow measuring system and flow measuring method

Abstract

The invention provides a laser Doppler flow measuring device, system and method for an open channel, and the device is disposed at a position close to a to-be-measured drainage basin of the open channel, and is used for measuring the flow of the to-be-measured drainage basin. The flow measuring device comprises an adjustable supporting frame, a multi-core fiber laser, a PLC, an environment sensor, a photoelectric detector, a signal amplifier, a frequency analyzer and an upper computer. The multi-core fiber laser is mounted on the adjustable support frame; the PLC is electrically connected with the environment sensor, the multi-core fiber laser and the frequency analyzer; the photoelectric detector is connected with the multi-core fiber laser through a multi-core fiber; the photoelectric detector, the signal amplifier, the frequency analyzer and the upper computer are electrically connected in sequence; the flow measurement result is accurate, a plurality of measurement points are obtained by adjusting the position and angle of the adjustable support frame, and the water flow condition is accurately reflected and the water flow environment change is flexibly coped by collecting the data of different measurement points in real time; the method is suitable for the field of open channel flow measurement in hydraulic engineering.

Description

Technical Field

[0001] The present application relates to the technical field of open channel flow measurement in water conservancy projects, and particularly relates to a laser Doppler open channel flow measurement device, a flow measurement system and a flow measurement method. Background Art

[0002] Nowadays, water conservation is given top priority in the water control concept of "giving priority to water conservation, achieving spatial balance, conducting systematic governance, and making concerted efforts with both hands". Open channel flow measurement is an important tool for water conservation management. By providing accurate flow data, it can help water resource managers optimize water use efficiency, reduce waste, and improve the utilization rate of water resources. Especially in agricultural irrigation and urban water management, the accuracy of open channel flow measurement is directly related to the effectiveness of water conservation. Therefore, open channel flow measurement plays a crucial role in ensuring the sustainable utilization of water resources and promoting water conservation work.

[0003] Currently, in the field of open channel flow measurement, the measurement methods mainly include orifice plate flowmeter method, electromagnetic flowmeter method, differential pressure flow measurement method, hydraulic structure flow measurement method, ultrasonic flowmeter method, etc. For the orifice plate flowmeter method, for low-flow or low-pressure liquids, the measurement accuracy is poor, and changes in the density, viscosity, etc. of the liquid will affect the measurement results. The electromagnetic flowmeter method is only applicable to conductive fluids such as water and sewage, and cannot measure non-conductive fluids. For the differential pressure flow measurement method, due to the presence of differential pressure devices (such as orifice plates, venturi tubes, etc.), certain local pressure losses will be introduced. For the hydraulic structure flow measurement method, the water flow in the open channel is greatly affected by factors such as the riverbed morphology and flow regime. If the flow regime is complex or the riverbed morphology is irregular, it may be difficult to accurately reflect the actual water flow condition, resulting in errors in the measurement data. For the ultrasonic flowmeter method, the propagation of ultrasonic signals will be affected when there are bubbles, solid particles or changes in liquid density. In the case of low flow, the measurement accuracy is poor.

[0004] Current laser Doppler measurement systems are mainly used for measuring solids, and their application in fluid measurement is relatively limited. Traditional laser flow meters use multiple independent optical elements such as beam splitters, plane mirrors, and lenses, which results in a complex system structure, a large volume, a difficult and time-consuming debugging process, and it is difficult to achieve ideal conditions, thus limiting the improvement of measurement accuracy. Secondly, the power output of single-core fiber lasers is limited by the physical properties of the fiber, which affects the accuracy and stability of Doppler measurement. Therefore, in order to increase the power output, it is usually necessary to increase the size of the fiber or use multiple fibers for coupling, but this increases the complexity of the system. Therefore, traditional laser Doppler velocity measurement technology requires the use of complex lasers and sensors, and there are problems with beam direction and focusing, resulting in certain limitations in its practical application in open channels. Summary of the Invention

[0005] To solve one of the above technical deficiencies, the present application provides a laser Doppler open channel flow measurement device, a flow measurement system, and a flow measurement method.

[0006] According to the first aspect of the present application, there is provided a laser Doppler open channel flow measurement device, which is arranged at a position close to the open channel to be measured, and is used for measuring the flow of the to-be-measured basin, including: an adjustable support frame, a multi-core fiber laser, a PLC controller, an environmental sensor, a photodetector, a signal amplifier, a frequency analyzer, and a host computer;

[0007] The multi-core fiber laser is installed on the adjustable support frame;

[0008] The PLC controller is electrically connected to the environmental sensor, the multi-core fiber laser, and the frequency analyzer respectively;

[0009] The photodetector is connected to the multi-core fiber laser through a multi-core fiber, and is used for receiving the optical signal reflected by the multi-core fiber laser and converting it into an electrical signal; the photodetector, the signal amplifier, the frequency analyzer, and the host computer are electrically connected in sequence.

[0010] Preferably, the multi-core fiber laser includes: a laser light source, a beam splitter, two collimators, a multi-core fiber fan-in / fan-out device, and a probe connected in sequence through a multi-core fiber; on the side of the probe away from the multi-core fiber fan-in / fan-out device, a focusing lens and a transmission lens are arranged in sequence; during use, the laser light source is transmitted to the beam splitter and then divided into two incident light beams, and the two incident light beams respectively enter the multi-core fiber fan-in / fan-out device through the two collimators and then output combined light through the probe. The combined light forms interference fringes corresponding to the combined light on the water surface of the to-be-measured basin through the focusing lens. When the water flow in the to-be-measured basin passes through the interference fringes, an optical signal is reflected through the transmission lens.

[0011] More preferably, the PLC controller is electrically connected to the probe, so as to control the combined light output by the probe through the PLC controller.

[0012] Preferably, the multi-core fiber is a seven-core fiber, and the combined light is a combination of any two of the seven-core fibers.

[0013] More preferably, the angle of the interference fringes is 30° to 60°.

[0014] Preferably, the adjustable support frame includes:

[0015] A telescopic support assembly, including a plurality of uniformly arranged telescopic support legs;

[0016] A fixed seat, connected to the top of each telescopic support leg;

[0017] The adjusting base is connected to the top of the fixed base, and an installation groove is provided on the top of the adjusting base;

[0018] An angle adjusting bracket, the bottom of the angle adjusting bracket is spherical and is rotatably connected in the installation groove; the multi-core fiber laser is installed on the top of the angle adjusting bracket.

[0019] Preferably, a bubble level is provided on the adjusting base.

[0020] Preferably, the telescopic support leg includes a first support rod and a second support rod; the first support rod is hollow, and at least one installation hole is provided on the side wall of the first support rod; the top of the second support rod is inserted into the bottom of the first support rod, and installation insertion rods corresponding to the number and position of the installation holes are provided on the outer wall of the second support rod, and the installation insertion rods are detachably inserted into the installation holes; a support foot is installed at the bottom of the second support rod, and a taper pin is installed at the bottom of the support foot.

[0021] According to a second aspect of the present application, a laser Doppler open channel flow measurement system is provided, including an open channel to be measured and a laser Doppler open channel flow measurement device arranged near the open channel to be measured; the laser Doppler open channel flow measurement device is the laser Doppler open channel flow measurement device as described in any one of the above.

[0022] According to a third aspect of the present application, a flow measurement method for a laser Doppler open channel flow measurement system is provided, including the following steps:

[0023] Install a laser Doppler open channel flow measurement device in the open channel to be measured;

[0024] Detect the environmental factors of the open channel to be measured through an environmental sensor;

[0025] Then, based on the environmental factor detection result, control the combined light output by the probe in the multi-core fiber laser through a PLC controller;

[0026] Receive the optical signal reflected by the transmission mirror in the multi-core fiber laser through a photodetector and convert it into an electrical signal;

[0027] Enhance the amplitude of the electrical signal through a signal amplifier;

[0028] Analyze the electrical signal with enhanced amplitude through a frequency analyzer, extract the frequency in the electrical signal, and calculate the flow velocity of the open channel to be measured;

[0029] Input the flow velocity of the open channel to be measured into the upper computer to calculate the flow rate of the open channel to be measured.

[0030] In this application, the multi-core fiber laser is arranged on an adjustable support frame, enabling adjustment of the multi-core fiber laser according to actual usage requirements by adjusting the adjustable support frame, so as to adjust the multi-core fiber laser to a suitable position. The environmental sensor continuously acquires the influencing factors in the environment and transmits them to the PLC controller. The PLC controller automatically adjusts parameters such as the power of the multi-core fiber laser and the fiber transmission characteristics, and can also automatically adjust parameters such as the sensitivity of the frequency analyzer to adapt to environmental changes and reduce the impact of environmental fluctuations on the measurement accuracy. The photodetector receives the optical signal output by the multi-core fiber laser. Due to the relative motion between the light beam and the particles, a Doppler frequency shift occurs between the optical signal and the laser light source. The photodetector converts the Doppler frequency shift signal into an electrical signal and enhances the intensity of the electrical signal through a signal amplifier to make the signal strong enough for subsequent processing and analysis of the optical signal. The frequency analyzer can extract the frequency components in the optical signal and then calculate the velocity of the fluid particles, that is, the water flow velocity at this measurement point on the water surface of the measured water area. The frequency analyzer is electrically connected to the upper computer, and the water flow rate is calculated through the upper computer.

[0031] The laser Doppler open channel flow measurement device provided in this application can achieve non-contact and non-invasive automatic real-time flow measurement with accurate measurement results, avoiding the problems in the prior art such as easy pollution of the water flow caused by contact with the water flow in the measured water area, easy wear and failure of the flow measurement device, and short service life. By adjusting the position and angle of the adjustable support frame, multiple measurement points are obtained. By collecting data at different measurement points in real time, the water flow conditions can be accurately reflected, and various dynamic water flow environments can be flexibly responded to, such as complex scenarios like tidal changes, sudden changes in flow velocity after heavy rain, and rapid fluctuations in flow velocity in the channel. In these complex scenarios, traditional flow velocity measurement methods cannot capture the changes in water flow in a timely manner, while the measurement device provided by the present invention can monitor the changes in flow velocity in real time and provide rapid feedback, which is of great significance for fields such as flood warning, irrigation scheduling, and water resource management.

[0032] Other features and advantages of this application will be described in the subsequent specification, and part of them will become obvious from the specification or be understood by implementing this application. The objectives and other advantages of this application can be achieved and obtained through the content pointed out in the written specification and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings described herein are used to provide a further understanding of this application and constitute a part of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation of this application. In the drawings:

[0034] Figure 1 It is a schematic structural diagram of the adjustable support frame in a laser Doppler open channel flow measurement device provided by this application;

[0035] Figure 2 Partial structural schematic diagram of a laser Doppler open channel flow measurement device provided by the present application;

[0036] Figure 3 Functional structural schematic diagram of the PLC controller provided by the present application;

[0037] Figure 4 Structural schematic diagram of the multi-core fiber laser provided by the present application;

[0038] Figure 5 Core wire distribution diagram of the seven-core fiber provided by the present application;

[0039] Figure 6 Schematic diagram of the interference fringes corresponding to the core wire combination provided by the present application;

[0040] Figure 7 Structural schematic diagram of a laser Doppler open channel flow measurement device provided by the present application;

[0041] In the figure:

[0042] 1 is the first core wire, 2 is the second core wire, 3 is the third core wire, 4 is the fourth core wire, 5 is the fifth core wire, 6 is the sixth core wire, 7 is the seventh core wire, 10 is the adjustable support frame, 20 is the multi-core fiber laser, 30 is the PLC controller, 40 is the environmental sensor, 50 is the photodetector, 60 is the signal amplifier, 70 is the frequency analyzer, 80 is the upper computer, 101 is the telescopic support assembly, 102 is the fixed seat, 103 is the adjustment seat, 104 is the angle adjustment bracket, 105 is the bubble level, 201 is the laser light source, 202 is the beam splitter, 203 is the collimator, 204 is the multi-core fiber fan-in / fan-out device, 205 is the probe, 206 is the focusing lens, 207 is the transmission lens, 208 is the interference fringe, 301 is the data acquisition module, 302 is the data processing module, 303 is the data storage module, 304 is the data output module. Detailed implementation manners

[0043] In order to make the technical solutions and advantages in the embodiments of the present application clearer and more understandable, the following further details the exemplary embodiments of the present application with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than an exhaustive list of all embodiments. It should be noted that, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other.

[0044] Such as Figure 1 And Figure 2As shown in the figure, in response to the above problems, an embodiment of the present application provides a laser Doppler open-channel flow measurement device, which is arranged at a position close to the open-channel basin to be measured and is used to measure the flow of the basin to be measured, including: an adjustable support frame 10, a multi-core fiber laser 20, a PLC controller 30, an environmental sensor 40, a photodetector 50, a signal amplifier 60, a frequency analyzer 70, and a host computer 80;

[0045] The multi-core fiber laser 20 is installed on the adjustable support frame 10;

[0046] The PLC controller 30 is electrically connected to the environmental sensor 40, the multi-core fiber laser 20, and the frequency analyzer 70 respectively; specifically, the environmental sensor 40 can be a temperature sensor, a humidity sensor, etc.;

[0047] The photodetector 50 is connected to the multi-core fiber laser 20 through a multi-core fiber, and is used to receive the optical signal reflected by the multi-core fiber laser 20 and convert it into an electrical signal; the photodetector 50, the signal amplifier 60, the frequency analyzer 70, and the host computer 80 are electrically connected in sequence; the host computer 80 can display the flow velocity distribution map, the time variation curve, etc. in real time, which is convenient for users to quickly grasp the water flow state and perform real-time monitoring and decision-making.

[0048] As Figure 3 shown, specifically, the PLC controller 30 includes a data acquisition module 301, a data processing module 302, a data storage module 303, and a data output module 304;

[0049] The environmental sensor 40 is electrically connected to the data acquisition module 301, the data acquisition module 301 is electrically connected to the data processing module 302 and the data storage module 303, the data processing module 302 is electrically connected to the data output module 304 and the data storage module 303, and the data output module 304 is electrically connected to the multi-core fiber laser 20 and the frequency analyzer 70 respectively. Through the data storage module, historical measurement data can be stored, which is convenient for subsequent analysis and decision-making, and is suitable for application environments of long-term detection and comparative analysis.

[0050] In this application, the multi-core fiber laser is arranged on an adjustable support frame, so that the multi-core fiber laser can be adjusted by adjusting the adjustable support frame according to the actual use requirements, so that the multi-core fiber laser is adjusted to a suitable position. The influencing factors in the environment are acquired in real time by the environmental sensor and transmitted to the PLC controller. The PLC controller automatically adjusts the parameters such as the power and fiber transmission characteristics of the multi-core fiber laser according to the influencing factors, and can also automatically adjust the sensitivity of the frequency analyzer and other parameters to adapt to environmental changes and reduce the impact of environmental fluctuations on measurement accuracy. The photoelectric detector receives the optical signal output by the multi-core fiber laser. Due to the relative motion of the light beam and the particles, a Doppler frequency shift occurs between the optical signal and the laser light source. The photoelectric detector converts the Doppler frequency shift signal into an electrical signal, and enhances the intensity of the electrical signal through the signal amplifier, so that the signal is strong enough to facilitate the subsequent processing and analysis of the optical signal; the frequency analyzer can extract the frequency component in the optical signal, and then calculate the speed of the fluid particles, that is, the water flow velocity of the measuring point in the water surface of the measured basin; the frequency analyzer is electrically connected to the host computer, and the water flow rate is calculated by the host computer.

[0051] The laser Doppler open channel flow measurement device provided by the present application can realize non-contact, non-invasive automatic real-time flow measurement, and the flow measurement result is accurate, which avoids the problem that the prior art needs to contact the water flow in the basin to be measured, which causes easy contamination of the water flow, easy wear and failure of the flow measurement device, and short service life. By adjusting the position and angle of the adjustable support frame, multiple measurement points are obtained, and the water flow conditions are accurately reflected by real-time data collection of different measurement points. It can flexibly respond to various dynamically changing water flow environments, such as tidal changes, sudden changes in flow velocity after heavy rain, rapid fluctuations in flow velocity in channels, and other complex scenes. In these complex scenes, traditional flow velocity measurement methods cannot capture changes in water flow in time, and the measurement device provided by the present invention can monitor the changes in flow velocity in real time and provide rapid feedback, which is of great significance to flood warning, irrigation scheduling, water resources management and other fields.

[0052] like Figure 4 As shown, further, the multi-core fiber laser 20 includes: a laser light source 201, a beam splitter 202, two collimators 203, a multi-core fiber fan-in and fan-out device 204 and a probe 205 connected in sequence through a multi-core optical fiber;

[0053] A focusing lens 206 and a transmission mirror 207 are sequentially arranged on the side of the probe 205 away from the multi-core optical fiber fan-in and fan-out device 204;

[0054] During use, the laser light source 201 is transmitted to the beam splitter 202 and then divided into two incident light beams. The two incident light beams respectively enter the multi-core fiber fan-in / fan-out device 204 through two collimators 203 and then output combined light through the probe 205. The combined light forms interference fringes 208 corresponding to the combined light on the water surface of the water area to be measured through the focusing lens 206. When the water flow in the water area to be measured passes through the interference fringes 208, scattered light is formed, and the scattered light reflects an optical signal through the transmission lens 207.

[0055] In this application, the light intensities and powers of the two incident light beams into which the laser light source is divided after being transmitted to the beam splitter are exactly the same. The two collimators can ensure that the focusing lens and the transmission lens are in preset positions, thereby ensuring that the incident light is transmitted along the preset path and avoiding the occurrence of deviation or misalignment. The multi-core fiber fan-in / fan-out device effectively distributes (fans out) or combines (fans in) multiple fiber signals to achieve a specific optical configuration. The focusing lens can concentrate the combined light on the water surface to be measured. The transmission lens can guide the scattered light into the photodetector for subsequent calculations. The use of multi-core fibers enables the prepared flow measurement device to have high precision and high spatial resolution, can effectively capture small changes in the water flow, and is more suitable for water areas to be measured with relatively complex flow velocity distributions, such as areas with obvious vortices, turbulences, or non-uniform flow velocities. This application uses a multi-core fiber laser for fluid measurement, greatly reducing the workload and error of manual measurement. The measurement is not affected by factors such as the density and viscosity of the fluid and will not interfere with the fluid.

[0056] Specifically, the laser light source 201 is a pump light source. More specifically, the pump light source is generated by a laser diode. By selecting different pump light sources, the wavelength of the laser light source can be adjusted, thereby exciting different energy levels of the doped ions (such as erbium, ytterbium, erbium-ytterbium composite fibers, etc.) in the multi-core fiber laser, and the pump efficiency, gain characteristics, and other performance of the prepared multi-core fiber laser can be improved.

[0057] Furthermore, the multi-core fiber is a seven-core fiber, and the combined light is a combination of any two of the seven-core fibers. The multi-core fiber can transmit the laser light source and the light beam. The multi-core fiber has multiple independent fiber channels that share the same cladding. Each fiber can independently transmit signals, and multiplexed signals can be transmitted in the same fiber, enabling multiple fiber transmission channels to be effectively integrated through the same fiber, thereby reducing the number of fibers and connection points and significantly simplifying the structure of the entire device. Compared with traditional fiber transmission schemes, it can greatly reduce the volume, reduce the weight of the device, and facilitate portability and deployment. In addition, the separate connection of the fiber and electrical components makes the operation have higher stability and fewer failure rates, further improving the reliability of long-term use.

[0058] Furthermore, the PLC controller 30 is electrically connected to the probe 205, so that the combined light output by the probe 205 can be controlled by the PLC controller 30. The probe can be adjusted through the PLC controller, and then the core wires with suitable distance and angle in the multi-core optical fiber are selected for combination, so as to select the interference fringes 208 for the best flow measurement and improve the flow measurement accuracy.

[0059] Specifically, during the flow measurement process, the interference fringes 208 with a small spacing, high clarity, moderate thickness, and an angle between 30° and 60° are selected.

[0060] As Figure 5 shown, taking a seven-core optical fiber as an example, the seven-core optical fiber includes a first core wire 1, a second core wire 2, a third core wire 3, a fourth core wire 4, a fifth core wire 5, a sixth core wire 6, and a seventh core wire 7, and their distribution is as Figure 5 shown; where the first core wire 1 is arranged in the middle, and the remaining six core wires are evenly distributed around the first core wire 1 in the circumferential direction; as Figure 6 shown, the following core wire combination methods are listed:

[0061] The third core wire and the sixth core wire, the interference fringes 208 are as Figure 6 (a) shown;

[0062] The second core wire and the seventh core wire, the interference fringes 208 are as Figure 6 (b) shown;

[0063] The first core wire and the third core wire, the interference fringes 208 are as Figure 6 (c) shown;

[0064] The second core wire and the third core wire, the interference fringes 208 are as Figure 6 (d) shown;

[0065] The third core wire and the fourth core wire, the interference fringes 208 are as Figure 6 (e) shown;

[0066] The second core wire and the fifth core wire, the interference fringes 208 are as Figure 6 (f) shown;

[0067] From Figure 6 (a) to Figure 6 (c), it can be seen that when emitting from different core distances, the thickness of the obtained interference fringes 208 and the distance between the interference fringes 208 are different. The farther the core distance, the smaller the spacing of the interference fringes 208.

[0068] From Figure 6 (d) to Figure 6 (f), it can be seen that when emitting from different core angles, the tilt angle of the obtained interference fringes 208 is also different. When the two core wires tilt to the right, the obtained interference fringes 208 tilt to the left.

[0069] In this application, a multi-core optical fiber is used for laser transmission. Compared with the traditional single-core optical fiber technology, it can provide more core combinations, and can adjust key characteristics such as the number (corresponding spacing), clarity, resolution, and angle of the interference fringes 208, and can be applied to environments with complex and unstable water flow. In practical applications, the interference conditions of the optical path can be adjusted according to actual measurement requirements to optimize the measurement accuracy. Especially when measuring fine flow velocity or high-precision flow velocity distribution, users can select the most suitable core combination to ensure the best effect of the interference fringes 208. By selecting interference fringes 208 with higher clarity and resolution, the system can more accurately capture the movement trajectories of particles in the water flow, thereby improving the accuracy of flow velocity measurement.

[0070] As Figure 7 shown, further, the adjustable support frame 10 includes:

[0071] A telescopic support assembly 101, including a plurality of uniformly arranged telescopic support legs; specifically, the telescopic support legs can be three.

[0072] A fixed seat 102, detachably connected to the top of each telescopic support leg, facilitating storage and handling.

[0073] An adjustment seat 103, connected to the top of the fixed seat 102, and an installation groove is provided at the top of the adjustment seat 103.

[0074] An angle adjustment bracket 104, the bottom of the angle adjustment bracket 104 is spherical and is rotatably connected in the installation groove; the multi-core fiber laser 20 is installed on the top of the angle adjustment bracket 104. Specifically, the installation groove is in the shape of a ball socket, and the diameter of the ball socket matches the diameter of the spherical shape at the bottom of the angle adjustment bracket, enabling rotational connection within a certain range.

[0075] The adjustable support frame provided by this application has a simple structure and is convenient to assemble. In practical applications, there is no need to transform the channel or install a fixed structure, and it can be flexibly installed beside the channel according to actual measurement requirements. Especially in complex or inaccessible environments, it can provide a convenient and efficient solution. Compared with traditional measuring instruments, it has a high degree of automation, is easy to operate, and is suitable for flow measurement of channels of different scales. The height can be adjusted through the telescopic support legs in the telescopic support assembly, thereby realizing the adjustment of the setting height of the multi-core fiber laser, enabling the multi-core fiber laser to be aligned with the target position in the channel, and making the measurement result more accurate. The bottom of the adjustment seat is connected to the fixed seat, making the structure more stable. The installation groove provided at the top of the adjustment seat corresponds to the spherical shape at the bottom of the angle adjustment bracket, enabling the angle adjustment bracket to be rotatably connected in the installation groove, facilitating the adjustment of the angle of the multi-core fiber laser and improving adaptability.

[0076] Specifically, each component in the adjustable support frame 10 is made of stainless steel, which is lightweight and convenient for installation and handling. More specifically, the telescopic support assembly 101 and the fixed seat 102, the fixed seat 102 and the adjustment seat 103, and the multi-core fiber laser 20 and the angle adjustment bracket 104 can all be connected by locking bolts to make the installation structure more stable.

[0077] Furthermore, a bubble level 105 is provided on the adjustment seat 103. The installation of the bubble level can assist the adjustment seat to be horizontally set, providing a reference for the angle adjustment of the multi-core fiber laser. Specifically, the bubble level 105 can be embedded in the outer wall of the adjustment seat 103.

[0078] Furthermore, the telescopic support leg includes a first rod and a second rod; the first rod is hollow, and at least one mounting hole is provided on the side wall of the first rod; the top of the second rod is inserted into the bottom of the first rod, and mounting insertion rods corresponding to the number and position of the mounting holes are provided on the outer wall of the second rod, and the mounting insertion rods are detachably inserted into the mounting holes; corresponding thread knobs are provided on the mounting insertion rods, and when the mounting insertion rods are detachably inserted into the mounting holes, they are locked by the thread knobs, making the structure more stable; a support foot is installed at the bottom of the second rod, and a taper pin is installed at the bottom of the support foot. Specifically, the bottom of the support foot and the taper pin are connected by mounting screws. More specifically, the length of the second rod does not exceed 0.5 times the length of the first rod.

[0079] In this application, the setting of the first rod and the second rod can realize the adjustment of the height of the telescopic support leg. By adjusting the height of each telescopic support leg, it can better adapt to the installation environment, and stable installation can also be achieved in an installation environment with uneven ground, thereby improving the stability of the multi-core fiber laser and the reliability of the measurement results. The tapered structure of the taper pin can provide better grip and firmness, enhancing the stability of the overall structure.

[0080] This application also provides a laser Doppler open-channel flow measurement system, including an open-channel basin to be measured and a laser Doppler open-channel flow measurement device arranged near the open-channel basin to be measured; the laser Doppler open-channel flow measurement device is the laser Doppler open-channel flow measurement device described in any one of the above.

[0081] Since the flow measurement system provided in this application includes the above-mentioned flow measurement device, it can be considered to have the relevant beneficial effects of the above-mentioned flow measurement device, which will not be elaborated here.

[0082] This application also provides a flow measurement method for a laser Doppler open-channel flow measurement system, including the following steps:

[0083] Install the laser Doppler open-channel flow measurement device in the open-channel basin to be measured;

[0084] The environmental factors of the open channel to be measured are detected by the environmental sensor 40;

[0085] Then, based on the detection results of the environmental factors, the combined light output by the probe 205 in the multi-core fiber laser 20 is controlled by the PLC controller 30;

[0086] The optical signal reflected by the transmissive mirror 207 in the multi-core fiber laser 20 is received by the photodetector 50 and converted into an electrical signal;

[0087] The amplitude of the electrical signal is enhanced by the signal amplifier 60;

[0088] The electrical signal with enhanced amplitude is analyzed by the frequency analyzer 70, the frequency in the electrical signal is extracted, and the flow velocity of the open channel to be measured is calculated;

[0089] The flow velocity of the open channel to be measured is input into the host computer 80 to calculate the flow rate of the open channel to be measured.

[0090] The flow measurement method provided by this application is simple to operate, can be adjusted in real time according to environmental factors, realizes automatic flow measurement, avoids human interference, has more accurate flow measurement results, can adapt to different usage environments, and has a wide application range.

[0091] In the description of this application, it should be understood that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application.

[0092] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0093] In this application, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, an electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, and can be the internal connection of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0094] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present application.

[0095] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A laser Doppler open channel flow measurement device is arranged at a position close to the open channel to be measured, and is used for measuring the flow of the to-be-measured basin. It is characterized in that, Comprising: An adjustable support frame (10), a multi-core fiber laser (20), a PLC controller (30), an environmental sensor (40), a photodetector (50), a signal amplifier (60), a frequency analyzer (70), and a host computer (80); The multi-core fiber laser (20) is installed on the adjustable support frame (10); The PLC controller (30) is electrically connected to the environmental sensor (40), the multi-core fiber laser (20), and the frequency analyzer (70) respectively; The photodetector (50) is connected to the multi-core fiber laser (20) through a multi-core fiber, and is used to receive the optical signal reflected by the multi-core fiber laser (20) and convert it into an electrical signal; the photodetector (50), the signal amplifier (60), the frequency analyzer (70), and the host computer (80) are electrically connected in sequence.

2. The laser Doppler open channel flow measurement device according to claim 1, characterized in that, The multi-core fiber laser (20) includes: a laser light source (201), a beam splitter (202), two collimators (203), a multi-core fiber fan-in / fan-out device (204), and a probe (205) connected in sequence through a multi-core fiber; On one side of the probe (205) away from the multi-core fiber fan-in / fan-out device (204), a focusing lens (206) and a transmissive mirror (207) are sequentially arranged; During use, the laser light source (201) is transmitted to the beam splitter (202) and then divided into two incident light beams. The two incident light beams respectively enter the multi-core fiber fan-in / fan-out device (204) through the two collimators (203) and then output combined light through the probe (205). The combined light forms interference fringes (208) corresponding to the combined light on the water surface of the water area to be measured through the focusing lens (206). When the water flow in the water area to be measured passes through the interference fringes (208), an optical signal is reflected through the transmissive mirror (207).

3. The laser Doppler open channel flow measurement device according to claim 2, characterized in that, The PLC controller (30) is electrically connected to the probe (205), so that the combined light output by the probe (205) can be controlled through the PLC controller (30).

4. The laser Doppler open channel flow measurement device according to claim 2, characterized in that The multi-core fiber is a seven-core fiber, and the combined light is a combination of any two of the seven-core fibers.

5. The laser Doppler open channel flow measurement device according to claim 2, characterized in that, The angle of the interference fringes (208) is 30° to 60°.

6. The laser Doppler open channel flow measurement device according to claim 1, characterized in that, The adjustable support frame (10) includes: A telescopic support assembly (101), including a plurality of uniformly arranged telescopic support legs; A fixed seat (102), connected to the top of each telescopic support leg; An adjustment seat (103), connected to the top of the fixed seat (102), and an installation groove is provided on the top of the adjustment seat (103); An angle adjustment bracket (104), the bottom of the angle adjustment bracket (104) is spherical and is rotatably connected in the installation groove; the multi-core fiber laser (20) is installed on the top of the angle adjustment bracket (104).

7. The laser Doppler open channel flow measurement device according to claim 6, characterized in that A bubble level (105) is provided on the adjustment seat (103).

8. The laser Doppler open channel flow measurement device according to claim 6, characterized in that, The telescopic support leg includes a first rod and a second rod; The first rod is hollow, and at least one installation hole is provided on the side wall of the first rod; The top of the second rod is inserted into the bottom of the first rod, and mounting insertion rods corresponding to the number and position of the mounting holes are arranged on the outer wall of the second rod, and the mounting insertion rods are detachably inserted into the mounting holes; A support foot is installed at the bottom of the second rod, and a taper pin is installed at the bottom of the support foot.

9. A laser Doppler open channel flow measurement system, characterized in that, It includes an open channel to be measured and a laser Doppler open channel flow measurement device arranged near the open channel to be measured; the laser Doppler open channel flow measurement device is the laser Doppler open channel flow measurement device according to any one of claims 1 to 8.

10. The flow measurement method of the laser Doppler open channel flow measurement system according to claim 9, characterized in that, It includes the following steps: Install a laser Doppler open channel flow measurement device in the open channel to be measured; Detect the environmental factors of the open channel to be measured through an environmental sensor (40); Based on the environmental factor detection results, control the combined light output by the probe (205) in the multi-core fiber laser (20) through a PLC controller (30); Receive and convert the optical signal reflected by the transmission mirror (207) in the multi-core fiber laser (20) into an electrical signal through a photodetector (50); Enhance the amplitude of the electrical signal through a signal amplifier (60); Analyze the electrical signal with enhanced amplitude through a frequency analyzer (70), extract the frequency in the electrical signal, and calculate the flow velocity of the open channel to be measured; Input the flow velocity of the open channel to be measured into a host computer (80) to calculate the flow rate of the open channel to be measured.

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