Fiber optic flowmeter and flow velocity measurement method

Abstract

The present application relates to a fiber optic flowmeter and a flow velocity measurement method. The fiber optic flowmeter includes: a detection light source; a heating light source; a probe including a detection optical fiber, a direct bandgap thermo-optical material component connected to the end face of the detection optical fiber, and a reflective layer connected to the terminal face of the direct bandgap thermo-optical material component; a processing module connected to the probe and receiving reflected light formed by the detection light passing through the reflective layer; an optical device, wherein the heating light source, the detection light source, and the detection optical fiber are all connected to the optical device to transmit the detection light and the heating light to the detection optical fiber via the optical device; the processing module is connected to the optical device, and the reflected light is transmitted to the processing module via the optical device. The present application realizes the integration of heating and temperature measurement by utilizing the law that the temperature of the direct bandgap thermo-optical material component changes with the transmission spectrum of the direct bandgap thermo-optical material component, facilitates miniaturized design, and utilizes the transmission spectrum drift characteristics to improve measurement accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of flow meters, and in particular to a fiber optic flow meter and a flow velocity measurement method. Background Art

[0002] Whether in industrial or biomedical fields, the detection and control of fluid flow rate is crucial. Measuring gas or liquid flow rate has important practical significance in industries such as food inspection, pharmaceuticals, medical devices, oil / gas exploration, environment, high-voltage power systems, chemical plants, and marine research.

[0003] In related technologies, optical fiber-based sensors can simultaneously measure temperature and flow rate based on the thermo-optical effect. This involves the absorption of light from a pump source by a special material within the optical fiber, generating a certain amount of heat. This heat is then measured using a fiber Bragg grating (FBG). As the fluid being measured removes heat from the sensor, the wavelength of the FBG shifts with temperature. This shift can be accurately detected by an optical spectrum analyzer, allowing the flow rate to be calculated based on the FBG wavelength shift.

[0004] However, heating is achieved by absorbing light through an optical fiber doped with special materials, and temperature is measured using a fiber Bragg grating, which separates heating and temperature measurement. This requires many components and is not conducive to miniaturization. In addition, the temperature is calculated by calculating the wavelength drift of the fiber Bragg grating, and the measurement accuracy is low. Summary of the Invention

[0005] The embodiments of the present application provide an optical fiber flow meter and a flow velocity measurement method to solve the technical problems in the related art of flow meters using optical fiber as a carrier, such as low measurement accuracy and difficulty in miniaturization.

[0006] In a first aspect, a fiber optic flow meter is provided, comprising:

[0007] a detection light source that emits detection light;

[0008] a heating light source that emits heating light;

[0009] A probe comprising a detection optical fiber, a direct bandgap thermo-optical material component connected to an end face of the detection optical fiber, and a reflective layer connected to a terminal face of the direct bandgap thermo-optical material component;

[0010] a processing module connected to the probe and receiving the reflected light formed by the detection light passing through the reflective layer;

[0011] An optical device, the heating light source, the detection light source, and the detection optical fiber are all connected to the optical device to transmit the detection light and the heating light to the detection optical fiber through the optical device, and the processing module is connected to the optical device, and the reflected light is transmitted to the processing module through the optical device.

[0012] In some embodiments, the processing module includes a detection instrument, which receives the reflected light to measure transmission spectrum data of the direct bandgap thermo-optical material component.

[0013] In some embodiments, the detection instrument includes a photodetector.

[0014] In some embodiments, the processing module further includes a controller connected to the detection instrument, and the transmission spectrum data of the direct bandgap thermo-optical material component is converted into flow rate data by the controller.

[0015] In some embodiments, the wavelength of the heating light is shorter than the wavelength of the transmission spectrum transition region of the direct bandgap thermo-optical material component;

[0016] The operating wavelength range of the detection light includes the wavelength range of the transmission spectrum transition region of the direct bandgap thermo-optical material component.

[0017] In some embodiments, the direct bandgap thermo-optical material component is made of gallium arsenide, silicon carbide, indium phosphide, or gallium nitride.

[0018] In some embodiments, the power of the heating light source remains constant.

[0019] In some embodiments, the fiber optic flow meter further includes a feedback circuit connected to the detection optical fiber for adjusting the power of the heating light source to maintain the probe temperature.

[0020] The beneficial effects of the technical solution provided by this application include:

[0021] The present application provides an optical fiber flowmeter. Due to the placement of a direct bandgap thermo-optical material component within a probe, the direct bandgap thermo-optical material component absorbs heating light emitted by a heating light source to increase its temperature. Different flow rates remove different amounts of heat from the direct bandgap thermo-optical material component, causing the temperature of the direct bandgap thermo-optical material component to change. As the temperature of the direct bandgap thermo-optical material component changes, the transmission spectrum of the direct bandgap thermo-optical material component drifts. A detection light is then irradiated by a detection light source, and the transmission spectrum data of the direct bandgap thermo-optical material component is measured by a processing module. When the flow rate in the measured area is different, the temperature of the direct bandgap thermo-optical material component is different, and the transmission spectrum data of the direct bandgap thermo-optical material component is also different. The flow rate data can be measured by corresponding the transmission spectrum data of the direct bandgap thermo-optical material component to the flow rate data. Since direct bandgap thermo-optical material components can absorb heating light to increase their temperature, temperature measurement can be performed based on the characteristic that the transmission spectrum data of the direct bandgap thermo-optical material components drifts with temperature changes. This can achieve the integration of heating and temperature measurement to facilitate the measurement of flow rate data. The number of components required is small, which facilitates miniaturized design. At the same time, based on the drift characteristics of the direct bandgap thermo-optical material components, the measurement accuracy is also improved.

[0022] In a second aspect, a flow velocity measurement method is provided, based on the above-mentioned fiber optic flow meter, comprising the following steps:

[0023] The flow rate data is obtained according to the transmission spectrum data of the direct bandgap thermo-optical material component.

[0024] In some embodiments, the flow rate data corresponding to the transmission spectrum data of the direct bandgap thermo-optical material component is obtained by calibrating the flow rate data according to a standard flow meter.

[0025] Another embodiment of the present application provides a flow velocity measurement method. Since it is based on the above-mentioned fiber optic flow meter, the beneficial effects of the flow velocity measurement method are consistent with the beneficial effects of the above-mentioned fiber optic flow meter, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0027] Figure 1 Schematic diagram of a fiber optic flow meter provided in an embodiment of the present application;

[0028] Figure 2 A schematic diagram of a probe provided in an embodiment of the present application;

[0029] Figure 3 Transmission spectrum of a direct bandgap thermo-optical material component provided in an embodiment of the present application;

[0030] Figure 4 Transmission spectra of the direct bandgap thermo-optical material component at different temperatures provided in an embodiment of the present application;

[0031] Figure 5 This is a graph showing the relationship between the central wavelength of the transition zone and temperature of the direct bandgap thermo-optical material component provided in an embodiment of the present application.

[0032] In the figure: 1. Detection optical fiber; 2. Direct bandgap thermo-optical material component; 3. Reflection layer; 4. Heating light; 5. Detection light; 6. Reflected light. DETAILED DESCRIPTION

[0033] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0034] The present invention provides an optical fiber flowmeter and flow velocity measurement method. A direct bandgap thermo-optical material component is connected to the end of a detection optical fiber, and the direct bandgap thermo-optical material component is heated by heating light. Simultaneously, the real-time transmission spectrum data of the direct bandgap thermo-optical material component is measured by detection light and a detection instrument. Based on the different temperatures of the direct bandgap thermo-optical material component at different flow rates and the different transmission spectrum data of the direct bandgap thermo-optical material component at different temperatures, the flow velocity data can be reflected by the transmission spectrum data of the direct bandgap thermo-optical material component. Temperature measurement is performed based on the characteristic that the transmission spectrum data of the direct bandgap thermo-optical material component drifts due to temperature changes. This allows for integrated heating and temperature measurement to facilitate measurement of flow velocity data. The number of components required is small, facilitating miniaturization. Measurements based on the drift characteristics of the direct bandgap thermo-optical material component also improve measurement accuracy. This addresses the technical issues of low measurement accuracy and difficulty in miniaturization in related art flowmeters using optical fibers as carriers.

[0035] Reference Figure 1 A fiber optic flowmeter includes a detection light source, a heating light source, a probe, a processing module, and an optical device. During measurement, the probe is extended into the fluid environment to be measured, and the flow velocity is sensed by the temperature change of the probe.

[0036] Reference Figure 2The probe includes a detection optical fiber 1, a direct bandgap thermo-optical material component 2, and a reflective layer 3. The direct bandgap thermo-optical material component 2 is connected to the end of the detection optical fiber 1 and bonded to the core end face of the detection optical fiber. The reflective layer 3 includes a reflective film coated on the terminal face of the direct bandgap thermo-optical material component 2 to reflect light. The direct bandgap thermo-optical material component 2 is made of gallium arsenide, silicon carbide, indium phosphide, or gallium nitride. In this embodiment, gallium arsenide is preferred.

[0037] In this embodiment, the optical device includes a fiber coupler. The heating light source, the detection light source, and the detection optical fiber are all connected to the fiber coupler, so that the detection light and the heating light are transmitted to the detection optical fiber through the fiber coupler. The processing module is connected to the fiber coupler, and the reflected light is transmitted to the processing module through the fiber coupler.

[0038] The detection light source emits detection light 5, and the heating light source emits heating light 4. Both the detection light source and the heating light source are connected to the probe via a fiber optic coupler, transmitting the detection light 5 and heating light 4 into the detection optical fiber 1. The wavelength of the heating light 4 is shorter than the wavelength at the lower boundary of the transition region of the transmission spectrum of the direct bandgap thermo-optical material component 2. The heating light 4 is absorbed by the direct bandgap thermo-optical material component 2, causing the probe to heat up. After the detection light 5 enters the probe through the fiber optic coupler, the reflective layer 3 reflects the detection light 5 to form reflected light 6. The reflected light 6 is transmitted to the processing module via the fiber optic coupler. The processing module obtains the transmission spectrum data of the direct bandgap thermo-optical material component 2 and converts it into flow rate data.

[0039] The wavelength range of the detection light 5 includes the wavelength range of the transmission spectrum transition region of the direct bandgap thermo-optical material component 2 .

[0040] This embodiment is based on the relationship between the temperature of the direct bandgap thermo-optical material component 2 and its transmission spectrum. Specifically, when the temperature of the direct bandgap thermo-optical material component 2 changes, the transmission spectrum of the direct bandgap thermo-optical material component 2 shifts accordingly. In this embodiment, the power of the heating light source remains constant to maintain the temperature of the probe's direct bandgap thermo-optical material component 2. When the probe is located in a fluid environment to be measured, the movement of the fluid removes heat from the probe. The faster the flow rate, the more heat is removed from the probe, i.e., the lower the temperature of the direct bandgap thermo-optical material component 2. Consequently, different flow rates correspond to different transmission spectra of the direct bandgap thermo-optical material component 2.

[0041] The faster the flow rate and the lower the probe temperature, the greater the shift in the transmission spectrum of the direct bandgap thermo-optical material component 2. The heating light 4 and the probe light 5 enter the probe simultaneously, performing heating and temperature measurement, while also providing feedback on changes in flow rate. Because some wavelengths of the probe light 5 are shorter than the lower boundary of the transition zone of the direct bandgap thermo-optical material component 2, the power of the heating light source must be at least 10 times that of the probe light source to minimize absorption of the probe light 5 by the direct bandgap thermo-optical material component 2. In this embodiment, after heating, the probe temperature reaches 60-70 degrees Celsius, increasing the probe's temperature fluctuation range and, consequently, the flow rate measurement range.

[0042] With this arrangement, due to the placement of the direct bandgap thermo-optical material component within the probe, the direct bandgap thermo-optical material component 2 absorbs the heating light 4 emitted by the heating light source to increase its temperature. Different flow rates remove different amounts of heat from the direct bandgap thermo-optical material component 2, causing the temperature of the direct bandgap thermo-optical material component 2 to change. As the temperature of the direct bandgap thermo-optical material component 2 changes, the transmission spectrum of the direct bandgap thermo-optical material component 2 shifts. The detection light 5 is then irradiated by the detection light source, and the transmission spectrum data of the direct bandgap thermo-optical material component 2 is measured by the processing module. Different flow rates in the measured area result in different temperatures of the direct bandgap thermo-optical material component 2, and thus different transmission spectrum data of the direct bandgap thermo-optical material component 2. Therefore, the flow velocity data can be measured by correlating the transmission spectrum data of the direct bandgap thermo-optical material component 2 with the flow velocity data. Since the direct bandgap thermo-optical material component 2 can absorb the heating light 4 to increase its temperature, and temperature measurement can be performed based on the characteristic that the transmission spectrum data of the direct bandgap thermo-optical material component drifts with temperature changes, heating and temperature measurement can be integrated to facilitate the measurement of flow rate data. The number of components required is small, which facilitates miniaturized design. At the same time, based on the drift characteristics of the direct bandgap thermo-optical material component 2, the measurement accuracy is also improved.

[0043] The fiber optic flowmeter also includes a transmission fiber and two input fibers. The two input fibers connect the detection light source and the heating light source to the optical device respectively, and the transmission fiber connects the probe to the optical device to transmit the detection light 5 and the heating light 4 to the probe through the optical device.

[0044] The fiber optic flowmeter also includes a receiving fiber, and the processing module includes a detection instrument. The receiving fiber connects the fiber coupler to the detection instrument. After the probe light 5 is reflected by the reflective layer 3, the resulting reflected light 6 enters the fiber coupler through the transmission fiber and is transmitted from the receiving fiber to the detection instrument. The detection instrument then measures the transmittance spectrum of the direct tape material portion 2. Changes in the transmittance spectrum measured by the detection instrument can be used to determine changes in probe temperature and the flow velocity of the fluid being measured.

[0045] In this embodiment, the detection instrument includes a photodetector. In this embodiment, the photodetector includes a spectrum analyzer, which can draw a transmission spectrum curve of the direct bandgap thermo-optical material component 2 .

[0046] The processing module also includes a controller, which is connected to the detection instrument. The controller processes and converts the transmission spectrum data of the direct bandgap thermo-optical material component 2 and outputs it as flow rate data. The controller includes data acquisition and processing functions. The controller collects and processes the digital signals obtained by the detection instrument and displays them on the host computer to display the flow rate data.

[0047] In this embodiment, since the power of the heating light source remains constant, the flow rate data can be obtained by measuring the temperature change of the probe and the corresponding shift in the transmission spectrum of the direct bandgap thermo-optical material component 2. In other embodiments, a feedback circuit can be connected to the detection optical fiber via a fiber coupler to adjust the power of the heating light source to maintain a constant probe temperature. When measuring flow rate, the feedback circuit adaptively increases or decreases the power of the heating light source to maintain the probe temperature, and the fluid flow rate can also be obtained from the output power of the heating light source. In other embodiments, a phase-locked loop mode can be used to periodically vary the optical power output of the heating light source to measure the fluid flow rate.

[0048] Another embodiment of the present application provides a flow velocity measurement method based on the above-mentioned fiber optic flow meter, comprising the following steps:

[0049] The flow rate data is obtained based on the transmission spectrum data of the direct bandgap thermo-optical material component.

[0050] During measurement, the direct bandgap thermo-optical material component 2 is placed in the fluid environment to be measured. The direct bandgap thermo-optical material component 2 is located at the end of the probe optical fiber. After the heating light 4 enters the detection optical fiber 1, the wavelength of the heating light 4 is less than the lower boundary wavelength of the transition zone of the direct bandgap thermo-optical material component 2. The direct bandgap thermo-optical material component 2 absorbs the heating light 4, causing its own temperature to rise. In this embodiment, the wavelength of the heating light 4 is less than the wavelength of the transition zone of the transmission spectrum of the direct bandgap thermo-optical material component 2. This facilitates the absorption of the heating light 4 by the direct bandgap thermo-optical material component 2, thereby heating the probe.

[0051] The probe light 5 and the heating light 4 enter the probe simultaneously. The wavelength range of the probe light 5 includes the wavelength range of the transition zone of the direct bandgap thermo-optical material component 2. Reflected light 6, formed by the probe light 5, enters a detection instrument, which measures the transmission spectrum data of the direct bandgap thermo-optical material component 2. In this embodiment, the transmission spectrum curve of the direct bandgap thermo-optical material component 2 is obtained by a spectrum detector, and the operating range of the spectrum detector is greater than the wavelength range of the probe light 5.

[0052] The transmission spectrum data of the direct bandgap thermo-optical material component 2 varies at different temperatures, and the flow rate affects the temperature of the direct bandgap thermo-optical material component 2. The greater the flow rate, the lower the temperature of the direct bandgap thermo-optical material component 2. The transmission spectrum data of the direct bandgap thermo-optical material component 2 can be used to obtain the flow rate data of the fluid environment to be measured.

[0053] With this arrangement, after the temperature of the probe is raised, the heat of the probe can be taken away by the fluid, thereby lowering the temperature of the direct bandgap thermo-optical material component 2. As the flow rate changes, the temperature and transmission spectrum data of the direct bandgap thermo-optical material component 2 change together. By measuring the transmission spectrum data of the direct bandgap thermo-optical material component 2, the flow rate data of the fluid environment to be measured can be inferred.

[0054] Reference Figure 3 , the transmission spectrum data of the direct bandgap type thermo-optical material component 2 includes transition region data, Figure 3 The transmission spectrum data of the direct bandgap thermo-optical material component 2 at the temperature T is shown. The transition region wavelength of the transmission spectrum data of the direct bandgap thermo-optical material component 2 is between λ1 and λ2.

[0055] Reference Figure 3 and Figure 4 When measuring the drift of the transmission spectrum data of the direct bandgap thermo-optical material component 2, a specific wavelength data can be preset in the transition zone data, and the drift of the transition zone of the direct bandgap thermo-optical material component 2 can be obtained based on the drift of the specific wavelength data. In this embodiment, the specific wavelength data is preferably the center wavelength of the transition zone of the direct bandgap thermo-optical material component 2. Figure 3 The central wavelength of the transition zone of the direct bandgap type thermo-optic material component 2 is λ. In the transition zone of the direct bandgap type thermo-optic material component 2, the change rate of the transmission spectrum at the central wavelength of the transition zone is the largest. The drift amount of the transition zone data of the direct bandgap type thermo-optic material component 2 can be easily known through the drift amount of the central wavelength of the transition zone of the direct bandgap type thermo-optic material component 2.

[0056] That is, the correspondence between the transmission spectrum data of the direct bandgap type thermo-optical material component 2 and the flow rate data can be measured according to the change of the flow rate data and the drift of the transition zone data of the direct bandgap type thermo-optical material component 2 . Figure 4 The transmission spectra of the direct bandgap thermo-optical material component 2 at temperatures T1 and T2 are shown in FIG. 1 , where T1 is greater than T2. ​​In this embodiment, the direct bandgap thermo-optical material component 2 includes a gallium arsenide layer, and the central wavelength of the transition region of the transmission spectrum of gallium arsenide varies with temperature as shown in FIG. Figure 5 As shown in FIG, the central wavelength of the transition region of the transmission spectrum of GaAs increases with increasing temperature.

[0057] Furthermore, the flow rate data can be calibrated by a standard flow meter. The flow rate data can be calibrated under different transmission spectrum data of the direct bandgap thermo-optical material component 2, and the flow rate data can be obtained through the transmission spectrum data of the direct bandgap thermo-optical material component 2.

[0058] In other embodiments, since fluids of different temperatures cause different temperature changes on the probe, a standard flowmeter can be used to calibrate the flow rates of fluids of different temperatures to correspond to the transmission spectrum data of the direct bandgap thermo-optical material component 2, thereby reducing the impact of different fluid temperatures on the flow rate measurement.

[0059] In this embodiment, heating and temperature measurement can be integrated to reflect the transmission spectrum data of the direct bandgap thermo-optical material component 2 in real time according to the probe temperature, so as to facilitate the flow rate in the measured fluid environment through the transmission spectrum data of the direct bandgap thermo-optical material component 2.

[0060] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply 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 on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0061] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0062] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A fiber optic flow meter, characterized in that: It includes: a detection light source that emits detection light; a heating light source that emits heating light; A probe comprising a detection optical fiber, a direct bandgap thermo-optical material component connected to an end face of the detection optical fiber, and a reflective layer connected to a terminal face of the direct bandgap thermo-optical material component; a processing module connected to the probe and receiving the reflected light formed by the detection light passing through the reflective layer; An optical device, the heating light source, the detection light source, and the detection optical fiber are all connected to the optical device to transmit the detection light and the heating light to the detection optical fiber through the optical device, and the processing module is connected to the optical device, and the reflected light is transmitted to the processing module through the optical device.

2. The fiber optic flow meter according to claim 1, characterized in that The processing module includes a detection instrument, which receives the reflected light to measure the transmission spectrum data of the direct bandgap thermo-optical material component.

3. The fiber optic flow meter according to claim 2, characterized in that: The detection instrument includes a photoelectric detector.

4. The fiber optic flow meter according to claim 2, characterized in that The processing module further includes a controller connected to the detection instrument, and the transmission spectrum data of the direct bandgap thermo-optical material component is converted into flow rate data by the controller.

5. The fiber optic flow meter according to claim 1, characterized in that: The wavelength of the heating light is shorter than the wavelength of the transmission spectrum transition region of the direct bandgap thermo-optical material component; The operating wavelength range of the detection light includes the wavelength range of the transmission spectrum transition region of the direct bandgap thermo-optical material component.

6. The fiber optic flow meter according to claim 1, characterized in that The material of the direct bandgap thermo-optical material component includes gallium arsenide, silicon carbide, indium phosphide or gallium nitride.

7. The fiber optic flow meter according to claim 1, characterized in that The power of the heating light source remains unchanged.

8. The fiber optic flow meter according to claim 1, characterized in that The system also includes a feedback circuit connected to the detection optical fiber, which adjusts the power of the heating light source to maintain the temperature of the probe.

9. A flow velocity measurement method based on the optical fiber flow meter according to any one of claims 1 to 8, characterized in that: The following steps are involved: The flow rate data is obtained based on the transmission spectrum data of the direct bandgap thermo-optical material component.

10. The flow velocity measurement method according to claim 9, characterized in that: The flow rate data is calibrated according to a standard flow meter to obtain the flow rate data corresponding to the transmission spectrum data of the direct bandgap thermo-optical material component.

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