System for measuring a fluid, method for measuring a fluid flow and use

Abstract

The application discloses a system for measuring fluid, a method for measuring fluid flow and an application. The system for measuring fluid comprises a laser Doppler module, a scanning execution module and a control processing module. The scanning execution module comprises an adjustable focus lens and a galvanometer. The scanning execution module is arranged to emit two laser beams with a phase difference from the laser Doppler module, and the two laser beams are sequentially irradiated to the measured fluid through the adjustable focus lens and the galvanometer, and then intersect to form a measurement body. Scattered light formed by particles in the measured fluid after flowing through the measurement body is sequentially irradiated to a receiving unit through the galvanometer and the adjustable focus lens. The control processing module converts the scattered light signal into an electric signal and performs at least one of the following operations: adjusting the focal length of the adjustable focus lens, adjusting the angle of the galvanometer, determining the flow rate and / or direction of the measured fluid, and calculating the flow of the measured fluid. The system is simple in device and small in moving parts, can be suitable for fluid flow measurement of unconventional channel sections, and is high in measurement accuracy and precision and wide in measurement range.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of fluid measurement, and particularly relates to a system for measuring fluid, a method for measuring fluid flow and use. BACKGROUND

[0002] Flow meters are the eyes of industrial production, and are closely related to national economy, national defense construction and scientific research, and play an important role in the national economy. They can be used for measuring the flow of gas, liquid, steam and other media. The current traditional flow meters include orifice flow meters, turbine flow meters, Venturi flow meters, volumetric flow meters, rotameters, vortex flow meters, Coriolis mass flow meters, ultrasonic flow meters, electromagnetic flow meters and the like. However, these flow meters have certain shortcomings, such as introducing large resistance, limited flow measurement range, or limited application medium site conditions, vibration, etc. For some unconventional objects, such as wind tunnels, water tunnels, special-shaped pipes, large-sized pipes and the like, the conventional flow meters are difficult to apply, and need to be specially customized, which is high in cost. SUMMARY

[0003] The present application is mainly proposed based on the following problems:

[0004] The inventors find that, for the existing flow meters, there are technical deficiencies such as introducing large resistance, limited flow measurement range, poor application object expansion universality and some unconventional measurement objects. It can be considered to measure the flow of fluid by using the principle of laser Doppler to measure the velocity of fluid in combination with the cross-sectional area of the special-shaped pipe to measure the flow of fluid in the special-shaped air pipe or the flow of fluid in the special-shaped water pipe, etc. In this way, the cross-sectional profile of the fluid to be measured can be determined by using the different feedback light signals when the laser is shot to the fluid to be measured and the pipe edge of the fluid to be measured, and then the cross-sectional area of the special-shaped pipe can be determined. However, in the actual operation process, in order to enable all areas of the pipe cross section to be contacted by the laser, an electric sliding table needs to be used to adjust the distance and angle of the laser shot to the fluid to be measured and the pipe edge. However, the adjustment capacity of the electric sliding table is limited. In order to meet the measurement requirements, the electric sliding table needs to have a large size in the horizontal direction and the vertical direction to meet the adjustment range, the moving part is large, and the operation efficiency is low. Especially for unconventional processing objects such as special-shaped pipes and large-sized pipes, the size requirement and adjustment capacity requirement of the electric sliding table are higher.

[0005] The present application aims to at least solve one of the technical problems in the related art. To this end, one object of the present application is to provide a system for measuring fluid, a method for measuring fluid flow and use. The system for measuring fluid not only has simple device, small moving part, low space occupancy, fast response, but also can adapt to the fluid flow measurement of unconventional channel cross section, and has high measurement accuracy and measurement precision, large measurement range.

[0006] In one aspect of the present application, the present application provides a system for measuring fluid, comprising:

[0007] a laser Doppler module, the laser Doppler module comprising a transmitting unit for transmitting two beams of laser light with a phase difference and a receiving unit adapted to receive scattered light generated by the two beams of laser light with a phase difference after contacting particles in the fluid to be measured;

[0008] a scanning execution module, the scanning execution module comprising a tunable focusing lens and a galvanometer, the tunable focusing lens being arranged between the galvanometer and the laser Doppler module, the scanning execution module being configured to cause the two beams of laser light with a phase difference to be sequentially transmitted through the tunable focusing lens and the galvanometer, and then to be emitted towards the fluid to be measured and intersect to form a measurement body, and the scattered light to be sequentially transmitted through the galvanometer and the tunable focusing lens, and then to be emitted towards the receiving unit;

[0009] a control processing module, the control processing module being connected to the laser Doppler module and the scanning execution module, the control processing module being adapted to convert the scattered light signal received by the receiving unit into an electrical signal, and to perform at least one of the following operations in combination with the electrical signal: adjusting the focal length of the tunable focusing lens, adjusting the angle of the galvanometer, determining the flow rate and / or direction of the fluid to be measured, and calculating the flow of the fluid to be measured.

[0010] The system for measuring fluid has at least the following beneficial effects: (1) the use of a tunable focusing lens and a galvanometer coupling instead of an electric sliding platform, the use of a tunable focusing lens to adjust the focal length of the laser light, and the use of a galvanometer to adjust the angle of the laser light when emitted towards the fluid to be measured, thereby flexibly adjusting the position of the measurement body when in contact with the particles in the fluid to be measured, not only having great adjustment capability and flexible operation, but also facilitating the determination of the cross-sectional profile of the fluid to be measured and the acquisition of the scattered light signal generated by the particles in the fluid to be measured at different positions of the cross section of the fluid to be measured, and further determining the flow rate and / or direction of the fluid to be measured by using the frequency difference of the scattered light signal and the phase difference of the laser light, which can adapt to the fluid flow measurement requirements of various fluid pipelines, especially the cross sections of unconventional pipelines, and has small moving parts, low space occupancy, fast response, low energy consumption, and can quickly perform operations; (2) the use of the laser Doppler principle, which has high measurement accuracy and measurement precision, a large measurement range, and can measure both positive and negative values.

[0011] In addition, the system for measuring fluid according to the above-mentioned embodiments of the present application can also have the following additional technical features:

[0012] In some embodiments of the present application, the pipeline of the fluid to be measured has a visible area.

[0013] In some embodiments of the present application, the tunable focusing lens is an electrically tunable focusing liquid lens.

[0014] In some embodiments of the present application, the adjustable angle of the galvanometer is -180°-180°.

[0015] In some embodiments of the present application, the laser Doppler module emits laser with a frequency greater than or equal to 10 kHz.

[0016] In some embodiments of the present application, the scanning step of the scanning execution module is 0.1 mm-1000 mm.

[0017] In some embodiments of the present application, the control processing module calculates the flow rate of the measured fluid with a frequency greater than or equal to 10 Hz.

[0018] In some embodiments of the present application, the transmitting unit comprises a laser, a Bragg device and a light-emitting lens, the laser emits laser light, which is divided into two beams with a phase difference by the Bragg device, and the two beams are emitted by the light-emitting lens respectively; the receiving unit comprises the light-emitting lens and a focusing lens, and the scattered light emitted to the receiving unit is focused by the focusing lens through the light-emitting lens.

[0019] In some embodiments of the present application, the control processing module comprises an optoelectronic conversion unit, a signal processing unit and a control feedback unit, the optoelectronic conversion unit is connected with the receiving unit and is adapted to convert the optical signal received by the receiving unit into an electrical signal; the signal processing unit is connected with the optoelectronic conversion unit and is adapted to determine the cross-sectional profile or the pipe profile of the measured fluid, and the flow rate and / or direction of the measured fluid based on the electrical signal, the phase difference and the frequency difference of the scattered light, and determine the scanning grid corresponding to the cross-sectional profile and / or calculate the flow rate of the measured fluid based on the determination result; the control feedback unit is connected with the optoelectronic conversion unit and / or the signal processing unit, and is connected with the adjustable focus lens, the galvanometer and the laser, and is adapted to at least one of the following operations based on the electrical signal, and / or the phase difference and the frequency difference of the scattered light: adjusting the laser frequency of the laser, adjusting the focal length of the adjustable focus lens, adjusting the angle of the galvanometer, adjusting the scanning step of the scanning execution module.

[0020] In another aspect of the present application, the present application provides a method for measuring the flow rate of fluid by using the above-mentioned system for measuring fluid, comprising:

[0021] (1) the emitting unit of the laser Doppler module emits two beams of laser with phase difference, the two beams of laser are processed by the scanning execution module, and then intersect to form scattered light generated by the contact between the measuring body and the particles in the measured fluid, the scattered light is processed by the scanning execution module, and then received by the receiving unit and converted into an optical signal and transmitted to the control processing module, and the control processing module combines the received signal to perform at least one of the following operations: at least one of adjusting the focal length of the adjustable focus lens, adjusting the angle of the galvanometer, adjusting the frequency of the laser emitted by the emitting unit, and adjusting the scanning step of the scanning execution module, so as to determine the cross-sectional profile of the measured fluid and a scanning grid corresponding to the cross-sectional profile;

[0022] (2) based on the scanning grid, the focal length of the adjustable focus lens and the angle of the galvanometer are changed, so as to obtain the velocity and direction of the measured fluid located in the cross-sectional profile of the measured fluid;

[0023] (3) the velocity of the measured fluid is spatially integrated in combination with the velocity of the measured fluid and the scanning grid, so as to obtain the flow of the measured fluid.

[0024] The method for measuring fluid flow has at least the following beneficial effects: (1) the adjustable focus lens is used to adjust the focal length of the laser, and the galvanometer is used to adjust the angle of the laser when it is shot to the fluid to be measured, so that the adjustment capacity is large, the operation is flexible, the determination of the cross-sectional profile of the measured fluid is facilitated, the scattered light signals generated by the contact between the particles at different positions of the measured fluid cross section and the measuring body are obtained, and then the flow rate and / or direction of the measured fluid are judged by using the frequency difference of the scattered light signals and the phase difference of the laser, which can adapt to the fluid flow measurement requirements of various fluid pipelines, especially the cross sections of unconventional pipelines, and the action components are small, the space occupancy is low, the response is fast, the energy consumption is small, and the operation can be quickly performed; (2) the laser Doppler principle is used, and the measurement accuracy and measurement precision are high, the measurement range is large, and the positive and negative values can be measured.

[0025] In addition, the method for measuring fluid flow according to the above embodiments of the application can also have the following additional technical features:

[0026] In some embodiments of the application, the laser processed by the scanning execution module or the measuring body contacts the particles in the measured fluid through the visible area on the measured fluid pipeline, and the scattered light is fed back to the scanning execution module through the visible area on the measured fluid pipeline.

[0027] In some embodiments of the application, the particles in the measured fluid include non-bubble particulate matter and / or bubbles.

[0028] In some embodiments of the present application, in step (1), the scanning step length of the region close to the edge of the cross-sectional profile of the measured fluid is smaller than the scanning step length of the region in the middle of the cross-sectional profile of the measured fluid.

[0029] In some embodiments of the present application, in step (1), the scanning grid corresponding to the cross-sectional profile is determined based on at least one of the cross-sectional profile, the laser frequency of the laser, the scanning step length of the scanning execution module, and the frequency of spatial integration of the velocity of the measured fluid.

[0030] In some embodiments of the present application, in step (2), the focal length of the adjustable focus lens and the angle of the galvanometer are changed based on the scanning grid so as to obtain the velocity of the measured fluid at different scanning grid positions within the cross-sectional profile of the measured fluid; and in step (3), the velocity of the measured fluid is spatially integrated by using a weighted process according to the scanning grid and the velocity distribution of the measured fluid at different scanning grid positions, so as to obtain the flow rate of the measured fluid.

[0031] In some embodiments of the present application, in step (1), a plurality of scanning grids corresponding to the cross-sectional profile are determined based on at least one of the cross-sectional profile, the laser frequency of the laser, the scanning step length of the scanning execution module, and the frequency of spatial integration of the velocity of the measured fluid, and the appropriate scanning grid is determined by comparing the difference of the flow rates obtained by spatial integration of the velocity of the measured fluid under different scanning grids.

[0032] In some embodiments of the present application, in step (1), the scanning step length of the region close to the edge of the cross-sectional profile of the measured fluid is 1 / 55-1 / 45 of the pipe diameter of the measured fluid, and the scanning step length of the region in the middle of the cross-sectional profile of the measured fluid is 1 / 12-1 / 8 of the pipe diameter of the measured fluid.

[0033] In some embodiments of the present application, the particle content in the measured fluid is 10-50 ppm.

[0034] In some embodiments of the present application, particles are supplied to the measured fluid so that the particle content in the measured fluid is 10-50 ppm.

[0035] In some embodiments of the present application, the particle size of the particles in the measured fluid is micron level.

[0036] In another aspect of the present application, the above-mentioned system for measuring fluid and / or the above-mentioned method for measuring fluid flow rate are used for measuring the flow rate of fluid in a regular pipe, an irregular pipe, or a large-size pipe.

[0037] Additional aspects and advantages of the present application will be made apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0038] The above and / or additional aspects and advantages of the present application will become apparent and be made clear to the reader after a review of the following description of a preferred embodiment taken in conjunction with the accompanying drawings.

[0039] Figure 1 is a structural schematic diagram of a system for measuring fluid according to one embodiment of the present application.

[0040] Figure 2 is a flow chart of a method for measuring fluid flow according to one embodiment of the present application. DETAILED DESCRIPTION

[0041] Embodiments of the present application are described in detail below with reference to the accompanying drawings, in which like or similar elements are denoted by the same or similar reference numerals, and examples of the embodiments are shown in the drawings. The embodiments described below are exemplary and are intended to explain the present application, and are not to be understood as limiting the present application.

[0042] In the description of the present application, the terms "first", "second", "third" and the like are used only for the purpose of description, and are not to be understood as indicating or implying relative importance or a specific number of the technical features indicated. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited. In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be interpreted broadly, for example, can be fixedly connected, or can be detachably connected, or can be integrated; can be mechanically connected, or can be electrically connected; can be directly connected, or can be indirectly connected through an intermediate medium; can be a communication inside two elements or an interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0043] In one aspect of the present application, the present application proposes a system for measuring fluid, referring to Figure 1 It is understood that the system comprises a laser Doppler module 10, a scanning execution module 20 and a control processing module 30. Among them:

[0044] The laser Doppler module 10 comprises a transmitting unit (not shown) and a receiving unit (not shown). The transmitting unit is used to emit two laser beams with a phase difference (referring to Figure 1The receiving unit is adapted to receive the scattered light 11c generated after the two beams of laser light with phase difference contact the particles in the measured fluid 41 (for the convenience of understanding the system for measuring the fluid, the fluid measurement system is explained by introducing the fluid measurement module 40 in the present application, wherein the fluid measurement module 40 includes the measured fluid 41, the particles (not shown) in the measured fluid, and the cross-sectional profile 42 of the measured fluid, which can also be understood as the inner wall cross section of the measured fluid pipe).

[0045] The scanning execution module includes the adjustable focus lens 21 and the galvanometer 22, the adjustable focus lens 21 is arranged between the galvanometer 22 and the laser Doppler module 10, and the scanning execution module 20 is arranged such that the two beams of laser light with phase difference pass through the adjustable focus lens 21 and the galvanometer 22 in sequence and then are emitted to the measured fluid 41 and intersect to form the measurement body 11d, and the scattered light 11c passes through the galvanometer 22 and the adjustable focus lens 21 in sequence and then is emitted to the receiving unit. The adjustable focus lens 21 is adapted to adjust the focal length of the laser light and the scattered light, and the galvanometer 22 is adapted to adjust the angle of the laser light and the scattered light. By coupling the adjustable focus lens 21 and the galvanometer 22, the measurement distance and the measurement angle of the measurement body 11d at different positions in the measured fluid 41 can be adjusted (for the convenience of understanding, refer to FIG. 2). Figure 1 It is understood that F represents the distance between the laser light emitted by the emitting unit and the measurement body), and the scattered light 11c is generated after the particles in the measured fluid flow through the measurement body 11d. In combination with the scanning execution module, the determination of the cross-sectional profile of the measured fluid is facilitated, and the scattered light signals generated by the particles flowing through different positions in the cross-sectional profile of the measured fluid contacting the measurement body are obtained.

[0046] The control processing module 30 is connected with the laser Doppler module 10 and the scanning execution module 20, and the control processing module 30 is adapted to convert the scattered light signal received by the receiving unit into an electrical signal, and in combination with the electrical signal, at least one of the following operations is performed: adjusting the focal length of the adjustable focus lens 21, adjusting the angle of the galvanometer 22, determining the flow rate and / or direction of the measured fluid 41, and calculating the flow of the measured fluid 41.

[0047] In the embodiment of the present application, when the system for measuring fluid is used to measure the fluid, a large-scale high spatial density scanning measurement can be firstly performed, the cross-sectional profile of the measured fluid (i.e. the inside of the fluid pipeline) is determined according to the scanning measurement result, the cross-sectional area of the fluid and the scanning range when the velocity of the fluid is measured subsequently are determined according to the cross-sectional profile, and specifically, two laser beams with a phase difference can be emitted by the emitting unit of the laser Doppler module, the two laser beams with the phase difference are sequentially focused by the adjustable focus lens and reflected by the galvanometer to be directed to the measured fluid, the two laser beams directed to the measured fluid intersect to form a measurement body (the measurement body can be located in the cross section of the measured fluid by changing the focal length of the adjustable focus lens and the angle of the galvanometer), and the scattered light generated by the particles in the measured fluid after flowing through the measurement body is sequentially reflected by the galvanometer, focused by the adjustable focus lens and received by the receiving unit of the laser Doppler module (wherein, the two laser beams with the phase difference generate two scattered lights after contacting the particles in the measured fluid, the two scattered lights can be focused by the adjustable focus lens and the galvanometer and converted into optical signals after being received by the receiving unit), the scattered light signals received by the receiving unit are converted into electrical signals by the control processing module, at least one of the focal length of the adjustable focus lens, the angle of the galvanometer, the frequency of the laser emitted by the emitting unit and the scanning step of the scanning execution module is changed in combination with the electrical signals and the phase difference of the two laser beams, so as to determine the cross-sectional profile of the measured fluid and the scanning grid corresponding to the cross-sectional profile, and the velocity of the measured fluid at different positions in the cross-sectional profile of the measured fluid can be measured based on the scanning grid (it can be understood that the scanning grid is actually a virtual grid, which can be regarded as a scanning range, and is used to determine the positions of different measurement sites in the cross-sectional profile of the measured fluid, and then the position and angle of the formed measurement body are adjusted, and the adjustment can be realized by changing the focal length of the adjustable focus lens and the angle of the galvanometer); after the cross-sectional profile of the measured fluid and the scanning grid are determined, the scanning position of the measurement body can be moved according to the predetermined scanning grid, and the velocity and direction of the measured fluid at different measurement sites in the cross-sectional profile are further measured, the velocity of the measured fluid is spatially integrated in combination with the scanning grid and the velocity of the measured fluid, and the flow of the measured fluid is obtained.

[0048] It can be understood that the velocity of the particles in the measured fluid is regarded as the velocity of the measured fluid in the present application, and the fluid usually contains diffusely distributed trace particles (such as dust in air) or micro-bubbles (such as micro-bubbles in water), and the size of the particles is extremely small, so that the fluid properties and flow state of the measured fluid are not damaged. When the purity of the measured fluid is relatively high and does not meet the testing requirements, a trace amount of particles (such as silica particles) can be artificially added to the measured fluid (the concentration after addition can be ppm level), so as to meet the testing requirements. Since the particle size and the addition amount are extremely small, the fluid properties and flow state of the original measured fluid are not damaged.

[0049] Therefore, the system for measuring fluid has at least the following beneficial effects: (1) the use of an adjustable focus lens and a galvanometer coupling instead of the use of a motorized slide, the adjustable focus lens is used to adjust the focal length of the laser, and the galvanometer is used to adjust the angle of the laser when it is directed to the fluid to be measured, so that the position of the measurement body when it contacts the particles in the fluid to be measured can be flexibly adjusted, not only the adjustment capacity is large, the operation is flexible, and the determination of the cross-sectional profile of the measured fluid can be realized, and the scattered light signals generated by the particles flowing through different positions of the cross section of the measured fluid and the measurement body are obtained, and then the flow rate and / or direction of the measured fluid are determined by using the frequency difference and the phase difference of the scattered light signals. The flow rate and / or direction of the measured fluid can be determined by using the frequency difference and the phase difference of the scattered light signals. It can adapt to the fluid flow measurement requirements of various fluid pipes, especially the cross sections of unconventional pipes, and the moving parts are small, the space occupancy is low, the response is fast, the energy consumption is low, and the operation can be quickly executed; (2) using the principle of laser Doppler, the measurement accuracy and measurement precision are high, the measurement range is large, and both positive and negative values can be measured.

[0050] In some embodiments of the present application, reference is made to Figure 1 It is understood that the pipe of the measured fluid 41 (which can be understood with reference to the cross-sectional profile 42 of the measured fluid) can have a visible area 42a, wherein the specific position and size of the visible area are not particularly limited, and those skilled in the art can flexibly choose according to actual needs, as long as laser incidence and scattered light emission can be realized. For example, the pipe of the measured fluid can be a transparent pipe, and the entire pipe wall can be regarded as a visible area; for another example, a closed visible window can be provided on the pipe of the measured fluid, such as an opening can be provided on the pipe wall of the measured fluid, and the opening is closed by a transparent material (such as a plastic film material, a glass substrate, etc.), and the transparent material and the position where the opening is located constitute a visible area; for another example, the visible area can be perpendicular to the flow direction of the measured fluid. The visible area on the pipe of the measured fluid is used for measuring the fluid, which can avoid introducing resistance in the measurement process and improve the accuracy of the measurement result. In addition, it can be understood that the system for measuring fluid in the present application can be combined with the visible area of the pipe of the measured fluid to form a dedicated fluid flow measurement device, or can be used as an independent device, which can be fixed by external installation and can be flexibly disassembled.

[0051] In some embodiments of the present application, reference is made to Figure 1It is understood that the transmitting unit of the laser Doppler module 10 can include the laser 11, the Bragg device 12, and the light-emitting lens 13, the laser emitted by the laser 11 is split into two beams of laser with a phase difference by the Bragg device 12, and the two beams of laser with the phase difference are emitted by the light-emitting lens 13; the receiving unit can include the light-emitting lens 13 and the focusing lens 14, the scattered light shot to the receiving unit is emitted by the light-emitting lens 13 and focused by the focusing lens 14, and the collected optical signal can be transmitted to the control processing module 30 through the optical fiber. As a specific example, the laser Doppler module can be a compact laser Doppler velocimeter (LDV), the laser emits laser, which is split into two beams with a phase difference by the Bragg device, forming two beams of laser with a phase difference, the laser is transmitted by the optical fiber, shaped, and focused by the light-emitting lens, and the two beams of laser intersect to form a measurement body; the tiny particles in the fluid flow through the measurement body, scatter the laser, and part of the scattered laser is converted into a signal optical fiber by the light-emitting lens and the focusing lens, and is introduced into the control processing module.

[0052] In some embodiments of the present application, with reference to Figure 1 It is understood that the control processing module 30 can include: a photoelectric conversion unit 31, a signal processing unit 32, and a control feedback unit 33, the photoelectric conversion unit 31 is connected with the receiving unit and is adapted to convert the optical signal received by the receiving unit into an electrical signal; the signal processing unit 32 is connected with the photoelectric conversion unit 31 and is adapted to determine the cross-sectional profile 42 or the pipeline profile (with reference to 42) of the measured fluid and the flow rate and / or direction of the measured fluid 41 based on the electrical signal, the phase difference, and the frequency difference of the scattered light, and determine the scanning grid 43 corresponding to the cross-sectional profile 42 and / or calculate the flow of the measured fluid based on the determination result; the control feedback unit 33 is connected with the photoelectric conversion unit 31 and / or the signal processing unit 32, and is connected with the adjustable focus lens 21, the galvanometer 22, and the laser 11, and is adapted to perform at least one of the following operations based on the electrical signal, and / or the phase difference and the frequency difference of the scattered light: adjusting the laser frequency of the laser 11, adjusting the focal length of the adjustable focus lens 21, adjusting the angle of the galvanometer 22, and adjusting the scanning step of the scanning execution module 20. Thus, it is more conducive to flexibly adjusting the measurement range, the measurement frequency, and the measurement accuracy, and realizing efficient, intelligent, high-accuracy, and high-precision measurement of the entire measurement system.

[0053] In some embodiments of the present application, the adjustable focus lens 21 can be an electrically adjustable focus liquid lens, which can realize large-range focal length adjustment, and by adjusting the focal length of the electrically adjustable focus liquid lens, the exit unit such as the light-emitting lens in the laser Doppler velocimeter is combined to realize adjustment of the measurement distance of the measurement body.

[0054] In some embodiments of the present application, the adjustable angle of the galvanometer 22 is -180°-180°. The galvanometer is an electrically controlled rotating mirror, which can control the scanning measurement angle of the measurement body, so that the adjustable angle of the galvanometer meets the given range requirement, and it is more convenient to expand the range interval that can be formed by the measurement body, and to realize flexible adjustment of the measurement distance and the measurement angle of the measurement body. The galvanometer is controlled by the control processing module in the scanning execution module, and the results of adjusting the focal length and the scanning angle can be fed back to the control processing module. Alternatively, the adjustable angle of the galvanometer 22 can be -90°-90° or -45°-45°.

[0055] According to the embodiments of the present application, a very large velocity measurement range can be obtained by means of the laser Doppler module 10, and both positive and negative values can be measured. In cooperation with the scanning execution module, a velocity measurement range of 0.1 m / s to several hundred m / s can be realized, and the measurement accuracy is generally above 99.5%. The velocity measurement frequency is very high, and the effective frequency of the laser is generally greater than 10 kHz. Through spatial velocity integration, large-range low-resistance high-precision flow measurement can be realized. Specifically, the laser frequency emitted by the laser Doppler module 10 can be greater than or equal to 10 kHz. Further, the scanning step of the scanning execution module 20 can be 0.1 mm-1000 mm. In the present application, the scanning step can be understood as the spatial distance between adjacent two measurement points in the scanning process, or can be understood as the spatial distance between adjacent two grid points in the scanning grid. The scanning step has a wide selection range, and can be flexibly adjusted according to the actual scanning requirements and accuracy requirements. For example, when the scanning accuracy needs to be improved, a smaller scanning step can be selected. For another example, when the cross section of the measured fluid is determined, a relatively larger scanning step can be selected when scanning to the middle position of the measured fluid, and a relatively smaller scanning step can be selected when scanning to the vicinity of the pipe of the measured fluid, so as to balance the measurement accuracy and the measurement efficiency. For another example, when the pipe size of the measured fluid is large, a larger scanning step can be selected.

[0056] Further, the control processing module 30 can calculate the flow of the measured fluid at a frequency greater than or equal to 10 Hz, so that the flow accuracy obtained by the calculation frequency is higher, and even reaches the mass flowmeter measurement accuracy level.

[0057] In another aspect of the present application, the present application proposes a method for measuring the flow of a fluid by using the above-mentioned system for measuring the fluid, with reference to Figure 1 and Figure 2 It is understood that the method comprises:

[0058] (1) determining the cross-sectional profile 42 of the measured fluid and the scanning grid corresponding to the cross-sectional profile 42. The specific implementation is as follows: the emitting unit of the laser Doppler module 10 emits two laser beams with a phase difference, and the two laser beams intersect to form the measurement body 11d after being processed by the scanning execution module 20, and the scattered light generated by the contact between the measurement body 11d and the particles in the measured fluid is received by the receiving unit after being processed by the scanning execution module 20 and is converted into an optical signal and transmitted to the control processing module 30, and the control processing module 30 combines the received signal to perform at least one of the following operations: at least one of adjusting the focal length of the adjustable focus lens 21, adjusting the angle of the galvanometer 22, adjusting the frequency of the laser emitted by the emitting unit, and adjusting the scanning step of the scanning execution module 20, so as to determine the cross-sectional profile 42 of the measured fluid and the scanning grid corresponding to the cross-sectional profile 42. (2) Changing the focal length of the adjustable focus lens 21 and the angle of the galvanometer 22 based on the scanning grid, so as to obtain the speed and direction of the measured fluid located in the cross-sectional profile 42 of the measured fluid. (3) Spatially integrating the speed of the measured fluid 41 in combination with the speed of the measured fluid 41 and the scanning grid, so as to obtain the flow of the measured fluid 41.

[0059] The method for measuring fluid flow has at least the following beneficial effects: (1) The adjustable focus lens is used to adjust the focal length of the laser, and the galvanometer is used to adjust the angle of the laser when it is shot to the measured fluid. Not only the adjustment ability is large, the operation is flexible, the determination of the cross-sectional profile of the measured fluid is convenient to realize, and the scattered light signals generated by the contact between the particles at different positions of the laser and the measured fluid cross section are obtained, and then the flow rate and / or direction of the measured fluid are judged by using the frequency difference of the scattered light signals and the phase difference of the laser. It can adapt to various fluid pipelines, especially the fluid flow measurement requirements of unconventional pipeline cross sections. Moreover, the action components are small, the space occupancy rate is low, the response is fast, the energy consumption is small, and the operation can be quickly performed; (2) Using the laser Doppler principle, the measurement accuracy and measurement precision are high, the measurement range is large, and the positive and negative values can be measured.

[0060] In some embodiments of the application, the laser processed by the scanning execution module 20 or the measurement body 11d contacts the particles in the measured fluid through the visible area 42a on the measured fluid pipeline (for reference 42) and the scattered light is fed back to the scanning execution module 20 through the visible area 42a on the measured fluid pipeline. The beneficial effects of measuring the fluid through the visible area and the specific setting mode of the visible area have been described in the foregoing part, which will not be repeated here.

[0061] In some embodiments of the present application, the particles in the measured fluid can include non-bubble particulate matter and / or bubbles, wherein the non-bubble particulate matter includes but is not limited to self-borne particulate matter in the measured fluid and / or artificially added micro-particles, and wherein the self-borne particulate matter in the measured fluid includes but is not limited to dust and the like. As some specific examples, when testing air flow, the particles in the measured fluid can be dust and the like borne by the measured fluid; when the measured fluid is a high-purity fluid, the particles in the measured fluid can be artificially added micro-particles. Further, the particle size of the particles in the measured fluid can be micron level, such as the size of the non-bubble particulate matter and / or bubbles can be in the micron range, which can be flexibly selected according to different fluid media, and the micron level particle size is small, which will not damage the properties and flow state of the fluid.

[0062] In some embodiments of the present application, when the purity of the measured fluid is high and difficult to meet the measurement requirements, a small amount of micro-particles can be appropriately added to the fluid. It should be noted that the material, density and the like of the micro-particles are not particularly limited, as long as they have good following properties in the measured fluid and can be uniformly dispersed in the measured fluid. For example, the micro-particles can include but are not limited to one or more of silica particles, titanium dioxide particles, PSP (polystyrene-based pyridine resin) particles, aluminum oxide particles and the like. For another example, the micro-particles can be hollow structure, which can further ensure the original fluid properties and flow state. Further, the particle content in the measured fluid can be 10 ppm to 50 ppm, such as the measured fluid with high purity can be supplied with micro-particles to make the particle content in the measured fluid be 10 ppm to 50 ppm, and the particle content in the measured fluid is controlled within the given range, which can not only meet the measurement requirements, but also further ensure the original fluid properties and flow state.

[0063] In some embodiments of the present application, in step (1), the scanning step length of the area close to the edge of the measured fluid cross-sectional profile 42 can be smaller than the scanning step length of the area located in the middle of the measured fluid cross section, which can further improve the accuracy and precision of the obtained measured fluid cross-sectional profile. As some specific examples, the scanning step length of the area close to the edge of the measured fluid cross-sectional profile 42 can be 1 / 55 to 1 / 45, such as 1 / 50, of the pipe diameter of the measured fluid, and the scanning step length of the area located in the middle of the measured fluid cross section can be 1 / 12 to 1 / 8, such as 1 / 10, of the pipe diameter of the measured fluid. It should be noted that the pipe diameter of the measured fluid can be the average pipe diameter, and by setting different scanning step lengths at different scanning positions, the measurement efficiency and the measurement accuracy and precision can be better balanced.

[0064] In some embodiments of the present application, in step (1), the scanning grid corresponding to the cross-sectional profile 42 can be determined based on at least one of the cross-sectional profile 42, the laser frequency of the laser 11, the scanning step of the scanning execution module 20, and the frequency of spatial integration of the velocity of the measured fluid 41. For example, when the measurement accuracy requirement is not high, the scanning step and / or the grid line spacing of the scanning grid can be relatively large, and the laser frequency of the laser can also be relatively low. Correspondingly, when the measurement accuracy requirement is high, the scanning step and / or the grid line spacing of the scanning grid can be relatively small, and the laser frequency can also be relatively high. It can be understood that the area of the scanning grid located in the cross-sectional profile should be close to or almost the same as the area of the cross-sectional profile.

[0065] In some embodiments of the present application, in step (2), the focal length of the adjustable focus lens 21 and the angle of the galvanometer 22 can be changed based on the scanning grid, so as to obtain the velocity of the measured fluid at different scanning grid positions located in the cross-sectional profile 42 of the measured fluid. For example, the position of the measurement body can be changed by changing the focal length of the adjustable focus lens and the angle of the galvanometer, so that the formation position of the measurement body includes but is not limited to the intersection points of each grid line of the scanning grid; in step (3), the velocity distribution of the measured fluid 41 at different scanning grid positions can be obtained according to the scanning grid and the velocity of the measured fluid 41 at different scanning grid positions, and the optical refractive correction of the measured fluid 41 is performed, and the velocity of the measured fluid 41 is spatially integrated by using a weighted processing, so as to obtain the flow of the measured fluid 41. Thus, the accuracy and precision of the measurement result can be further improved. When the velocity of the measured fluid 41 is spatially integrated, the velocity of the measured fluid 41 can be integrated by using the number of grids of the scanning grid, or the velocity of the measured fluid 41 can be integrated by using the area of each grid in the scanning grid, and the latter processing mode is preferred.

[0066] In some embodiments of the present application, in step (1), a plurality of scanning grids corresponding to the cross-sectional profile 42 can be determined based on at least one of the cross-sectional profile 42, the laser frequency of the laser 11, the scanning step of the scanning execution module 20, and the frequency of spatial integration of the velocity of the measured fluid 41. By comparing the difference of the flow obtained by spatially integrating the velocity of the measured fluid 41 under different scanning grids, a suitable scanning grid can be determined. In this way, the reliability and accuracy of the measurement result can be further improved, and the adverse effect of the flow mutation in the local region of the measured fluid on the accuracy of the final measurement result can be avoided.

[0067] In addition, it should be noted that the features and effects described for the system for measuring the fluid are also applicable to the method for measuring the flow of the fluid, which will not be described here.

[0068] In yet another aspect of the present application, the present application provides use of the above-mentioned system for measuring fluid and / or the above-mentioned method for measuring fluid flow in measuring fluid flow in regular pipes, irregular pipes or large-size pipes. The features and effects described for the above-mentioned system for measuring fluid and method for measuring fluid flow are equally applicable to the use, which will not be repeated here. In general, the measurement speed, reliability, accuracy, precision, applicability, etc. of the above-mentioned system for measuring fluid and method for measuring fluid flow are better.

[0069] In summary, the system for measuring fluid and method for measuring fluid flow of the above-mentioned embodiments of the present application are based on the principle of laser Doppler velocimetry, realized by integrating laser Doppler velocimetry and scanning functions in a manner similar to existing flowmeters, and can have the following beneficial effects:

[0070] 1. Using the principle of laser Doppler, the measurement speed range is extremely large, the accuracy of the measured flow is high, which can reach 99% or above, such as 99.5%, or even reach the measurement precision level of mass flowmeters; the measurement range is large, both positive and negative values can be measured; the measurement frequency is high; by integrating the space velocity, large-range low-resistance high-precision flow measurement can be realized.

[0071] 2. Laser Doppler measurement body is quickly scanned by means of a galvanometer and an adjustable focus lens (such as an electrically adjustable focus liquid lens), which is relatively to the form of an electrically adjustable focus liquid lens, not only the moving parts are small in size, fast in speed and quick in response, and can quickly perform scanning actions, but also the energy consumption is low, the reliability is high, and the service life is long.

[0072] 3. The control processing module integrates the electrically adjustable lens, the galvanometer and the velocity information to realize scanning of the pipe cross section, and further integrates the scanning grid scheme to integrate the cross-sectional flow. Not only the measurement method is intelligent, different scanning methods can be selected, the scanning method can be adjusted according to the demand, etc.

[0073] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above-mentioned terms is not necessarily for the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0074] Although the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are exemplary and are not to be construed as limiting the present application, and that variations, modifications, substitutions and changes can be made by those skilled in the art without departing from the scope of the present application.

Claims

1. A system for measuring a fluid, characterized by, The application relates to a laser Doppler module, a scanning execution module and a control processing module. The laser Doppler module comprises a transmitting unit and a receiving unit, the transmitting unit is used for transmitting two beams of laser light with a phase difference, and the receiving unit is adapted to receive scattered light generated after the two beams of laser light with a phase difference contact particles in a measured fluid. The scanning execution module comprises an adjustable focus lens and a galvanometer, the adjustable focus lens is arranged between the galvanometer and the laser Doppler module, and the scanning execution module is arranged to make the two beams of laser light with a phase difference pass through the adjustable focus lens and the galvanometer in sequence, then be emitted to the measured fluid, and intersect to form a measurement body, and make the scattered light pass through the galvanometer and the adjustable focus lens in sequence, then be emitted to the receiving unit. The control processing module is connected with the laser Doppler module and the scanning execution module, is adapted to convert a scattered light signal received by the receiving unit into an electric signal, and is combined with the electric signal to perform at least one of the following operations: adjusting a focal length of the adjustable focus lens, adjusting an angle of the galvanometer, determining a flow rate and / or direction of the measured fluid, and calculating a flow of the measured fluid. The transmitting unit comprises a laser, a Bragg device and an emitting lens, laser light emitted by the laser is divided into two beams of laser light with a phase difference through the Bragg device, and the two beams of laser light with a phase difference are emitted through the emitting lens respectively; the receiving unit comprises the emitting lens and a focusing lens, and the scattered light emitted to the receiving unit is emitted into the focusing lens through the emitting lens and focused. The control processing module comprises: A photoelectric conversion unit connected with the receiving unit and adapted to convert an optical signal received by the receiving unit into an electric signal; A signal processing unit connected with the photoelectric conversion unit and adapted to judge a cross-sectional profile or a pipeline profile of the measured fluid and a flow rate and / or direction of the measured fluid based on the electric signal, the phase difference and a frequency difference of the scattered light, and determine a scanning grid corresponding to the cross-sectional profile and / or calculate the flow of the measured fluid based on a judgment result; A control feedback unit connected with the photoelectric conversion unit and / or the signal processing unit and connected with the adjustable focus lens, the galvanometer and the laser, and adapted to perform at least one of the following operations: adjusting a laser frequency of the laser, adjusting the focal length of the adjustable focus lens, adjusting the angle of the galvanometer, and adjusting a scanning step length of the scanning execution module based on the electric signal, and / or the phase difference and the frequency difference of the scattered light.

2. The system for measuring a fluid of claim 1, wherein, At least one of the following conditions is met: The pipeline of the measured fluid has a visible area; The adjustable focus lens is an electrically adjustable focus liquid lens; The adjustable angle of the galvanometer is -180 DEG ~ 180 DEG.

3. The system for measuring a fluid of claim 1, wherein, At least one of the following conditions is met: The laser frequency of the laser Doppler module is greater than or equal to 10 kHz; The scanning step length of the scanning execution module is 0.1 mm-1000 mm; The frequency of calculating the flow of the measured fluid by the control processing module is greater than or equal to 10 Hz.

4. A method of measuring fluid flow using the system of any one of claims 1 to 3, wherein, The application relates to a laser Doppler module, a scanning execution module and a control processing module. (1) the emitting unit of the laser Doppler module emits two beams of laser with phase difference, and the two beams of laser intersect to form scattered light after being processed by the scanning execution module, the scattered light is received by the receiving unit after being processed by the scanning execution module and is converted into optical signal and transmitted to the control processing module, the control processing module combines the received signal to perform at least one of the following operations: at least one of adjusting the focal length of the adjustable focus lens, adjusting the angle of the galvanometer, adjusting the frequency of the laser emitted by the emitting unit, adjusting the scanning step of the scanning execution module, so as to determine the cross-sectional profile of the measured fluid and the scanning grid corresponding to the cross-sectional profile; (2) based on the scanning grid, the focal length of the adjustable focus lens and the angle of the galvanometer are changed, so as to obtain the velocity and direction of the measured fluid located in the cross-sectional profile of the measured fluid; (3) the velocity of the measured fluid is spatially integrated by combining the velocity of the measured fluid and the scanning grid, so as to obtain the flow of the measured fluid.

5. The method of claim 4, wherein, At least one of the following five conditions is met: The laser processed by the scanning execution module or the measuring body passes through the visible area on the measured fluid pipeline and contacts the particles in the measured fluid, and the scattered light is fed back to the scanning execution module through the visible area on the measured fluid pipeline; The particles in the measured fluid include non-bubble particulate matter and / or bubbles; In step (1), the scanning step of the area close to the edge of the cross-sectional profile of the measured fluid is smaller than the scanning step of the area located in the middle of the cross-sectional profile of the measured fluid; In step (1), based on at least one of the cross-sectional profile, the laser frequency of the laser, the scanning step of the scanning execution module and the frequency of spatial integration of the velocity of the measured fluid, the scanning grid corresponding to the cross-sectional profile is determined; In step (2), based on the scanning grid, the focal length of the adjustable focus lens and the angle of the galvanometer are changed, so as to obtain the velocity of the measured fluid at different scanning grid positions located in the cross-sectional profile of the measured fluid; in step (3), according to the scanning grid and the velocity distribution of the measured fluid at different scanning grid positions, the velocity of the measured fluid is spatially integrated by adopting weighted processing to correct the optical refractive index of the measured fluid, so as to obtain the flow of the measured fluid.

6. The method of claim 5, wherein, In step (1), based on at least one of the cross-sectional profile, the laser frequency of the laser, the scanning step of the scanning execution module and the frequency of spatial integration of the velocity of the measured fluid, a plurality of scanning grids corresponding to the cross-sectional profile are determined, and the appropriate scanning grid is determined by comparing the difference of the flow obtained by spatially integrating the velocity of the measured fluid under different scanning grids; and / or, In step (1), the scanning step of the area close to the edge of the cross-sectional profile of the measured fluid is 1 / 55~1 / 45 of the diameter of the measured fluid pipeline, and the scanning step of the area located in the middle of the cross-sectional profile of the measured fluid is 1 / 12~1 / 8 of the diameter of the measured fluid pipeline.

7. The method of any one of claims 4-6, wherein, At least one of the following three conditions is met: The particle content in the measured fluid is 10 ppm to 50 ppm; Particles are supplied to the measured fluid so that the particle content in the measured fluid is 10 ppm to 50 ppm; The particle size of the particles in the measured fluid is micrometer level.

8. Use of the system for measuring fluid according to any one of claims 1 to 3 or the method according to any one of claims 4 to 7 for measuring the flow rate of fluid in a regular pipe, an irregular pipe or a large size pipe.

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