Online Measuring Device and Method for Powder Fuel Mass Flow Rate Based on Laser Modulation

Abstract

An on-line measuring device and method for the mass flow rate of powder fuel based on laser modulation belong to the technical field of laser spectroscopy applications. A semiconductor laser and a solid laser are vertically arranged. There are a chopper, a first beam splitter, a beam combiner, a second beam splitter and a weak optical signal detection system in the laser transmission path of the semiconductor laser; the laser output by the solid laser is combined with the laser of the semiconductor laser by the beam combiner after being subjected to structured light modulation and shaping system; a power meter cooperates with the first beam splitter; a high-speed CMOS camera cooperates with the second beam splitter. The method is as follows: device construction and debugging; optical signal processing; synchronous measurement of the density and flow rate of powder fuel particles; calibration of the on-line measuring device, establishing the calibration relationship between the density and flow rate of powder fuel particles and the mass flow rate, and obtaining the instantaneous flow rate information of powder fuel in real time. The present invention improves the signal-to-noise ratio of the detection signal and solves the real-time high-precision measurement of the mass flow rate under the background of high-speed dense gas-solid two-phase flow.

Description

Technical Field

[0001] The present invention relates to an on-line measuring device and method for the mass flow rate of powder fuel based on laser modulation, belonging to the technical field of laser spectroscopy applications. Background Technique

[0002] A powder engine is a new type of engine that uses high-energy metals or powders such as boron as fuel, and has broad application scenarios in new-generation long-range air-to-air missiles, air-to-ground missiles, and air defense missiles. Based on the action of the fluidizing gas, the powder fuel enters the combustion chamber in the form of a gas-solid two-phase for combustion, thereby generating thrust. The powder fuel supply system is the core component of the powder engine, and the on-line real-time high-precision measurement of the mass flow rate of the powder fuel is the key to ensuring that the powder engine has adjustable thrust and multi-pulse start.

[0003] In order to meet the working requirements of the powder engine in multi-task scenarios, the mass flow rate of the powder fuel must be adjustable and stable under constant working conditions. Therefore, the realization of real-time high-precision measurement of the mass flow rate of the powder fuel is an important basis for developing high-reliable powder supply technology to achieve thrust follow-up control of the powder engine.

[0004] Currently, the measurement methods for the mass flow rate of powder fuel, from the perspective of measurement forms, are mainly divided into direct measurement methods and indirect measurement methods, and have the following limitations:

[0005] I. Direct measurement methods (such as Coriolis flowmeters and weighing methods):

[0006] 1. The Coriolis flowmeter is independent of fluid properties. Although it has high measurement accuracy and does not affect the flow field, and is widely used for the mass flow measurement of gases, liquids, and gas-liquid two-phase flows, it is not suitable for the measurement of dense gas-solid two-phase flows.

[0007] 2. The weighing method uses an electronic balance for weighing. Although it can measure the time-averaged mass flow rate, the measurement time is long, and it is impossible to provide real-time feedback on the instantaneous mass flow rate during the dynamic process of powder fuel transportation.

[0008] II. Indirect measurement methods (such as piston rate conversion method, pressure conversion method, and particle concentration-velocity correlation method):

[0009] 1. Both the piston rate conversion method and the pressure conversion method are steady-state measurement means, and can only obtain the average mass flow rate of the powder fuel over a period of time, and cannot achieve on-line flow rate measurement, making it difficult to meet the requirements of real-time and precise control of powder transportation.

[0010] 2. Although the particle concentration-velocity correlation method can calculate the mass flow rate by measuring the concentration and velocity of particles through the attenuation method and cross-correlation method, this method is affected by the laser transmission and detection in a dense gas-solid two-phase flow environment, resulting in large fluctuations in the detection signal, strong noise, and low signal-to-noise ratio, making it impossible to guarantee measurement accuracy. Summary of the Invention

[0011] In order to solve the problems existing in the background technology, the present invention provides an online measurement device and method for the mass flow rate of powdered fuel based on laser modulation.

[0012] To achieve the above-mentioned objectives, the present invention adopts the following technical solutions: a device for online measurement of powder fuel mass flow rate based on laser modulation, comprising a structured light modulation and shaping system, a second beam splitter, a beam combining mirror, a chopper, a power meter, a high-speed CMOS camera, a weak light signal detection system, a first beam splitter, a semiconductor laser and a solid-state laser; the laser polarization direction of the semiconductor laser is arranged perpendicular to the laser polarization direction of the solid-state laser, and a chopper, a first beam splitter, a beam combining mirror, a second beam splitter and a weak light signal detection system are sequentially arranged along the laser transmission direction on the laser transmission path of the semiconductor laser; the laser output by the solid-state laser is combined with the laser output by the semiconductor laser through the beam combining mirror after passing through the structured light modulation and shaping system; the power meter is arranged in conjunction with the first beam splitter; and the high-speed CMOS camera is arranged in conjunction with the second beam splitter.

[0013] The laser wavelength output by the semiconductor laser is 630 nm.

[0014] The laser wavelength output by the solid laser is 532 nm.

[0015] A filter is provided at the front end of the lens of the high-speed CMOS camera.

[0016] The weak light signal detection system comprises a focusing mirror, a detector, an AC amplifier and a data acquisition system which are arranged in sequence.

[0017] The present invention provides a method for online measuring the mass flow rate of powdered fuel based on laser modulation, the method comprising the following steps:

[0018] S1: Construction and debugging of online measurement equipment;

[0019] S2: optical signal processing before mass flow rate measurement;

[0020] S201: The semiconductor laser outputs continuous laser light;

[0021] S202: The chopper rotates to modulate the continuous laser into a modulated laser with a fixed period, and generates a square wave signal with the same frequency as the modulated laser;

[0022] S203: The square wave signal is split by the second beam splitter and then passes through a power meter to record optical signal information;

[0023] S204: The output laser of the solid-state laser is modulated and shaped into a sheet laser by the structured light modulation and shaping system, and then combined with the modulated laser by a beam combiner;

[0024] S205: The combined laser beam is incident on the area to be measured;

[0025] S206: The focusing mirror performs spatial filtering on the combined laser beam;

[0026] S207: The detector converts the combined laser light signal into an electrical signal;

[0027] S208: The electrical signal passes through an AC amplifier to filter out DC noise components and amplify AC signal components;

[0028] S209: The data acquisition system acquires the measurement signal and the reference signal;

[0029] S2010: The data acquisition system transmits the measurement signal and the reference signal to the computer for phase-locked processing and analysis to obtain target radiation related information, and converts the target radiation related information into radiation brightness for correlating particle density and velocity information.

[0030] S3: Simultaneous measurement of powdered fuel particle density and flow rate;

[0031] S301: Using the extinction method to compare the relationship between the transmitted light intensity and the incident intensity of the modulated laser, the particle density of the powdered fuel is measured;

[0032] S302: After the sheet laser irradiates the area to be measured, a high-speed CMOS camera is used to capture a scattered image of the powdered fuel particles;

[0033] S303: Particle flow rate measurement:

[0034] For low concentration areas, the particle velocity of the powdered fuel was measured by PIV;

[0035] For high-concentration areas, the movement of pixels or feature points between consecutive image frames in the image sequence is calculated using the optical flow algorithm to obtain the particle flow rate of the powdered fuel.

[0036] S4: The online measuring device is calibrated using the weighing method to establish a calibration relationship between the density and flow velocity of the powder fuel particles and the mass flow rate, and to obtain the instantaneous flow rate information of the powder fuel in real time.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention utilizes an optical measurement method that combines optical chopping and lock-in amplification methods, improves the signal-to-noise ratio of the detection signal, obtains information related to the target radiation, realizes the synchronous measurement of particle density and flow velocity around the extinction method, particle image velocimetry, and optical flow method, and uses a machine learning algorithm to establish a non-linear function relationship between the mass flow rate and particle density and flow velocity, solving the problem of real-time high-precision measurement of the mass flow rate under the background of high-speed dense gas-solid two-phase flow. Brief Description of the Drawings

[0039] Figure 1 is a schematic structural diagram of the present invention. Detailed Embodiment

[0040] The following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0041] An on-line measurement device for the mass flow rate of powder fuel based on laser modulation includes a structured light modulation and shaping system 1, a second beam splitter 2, a beam combiner 3, a chopper 4, a power meter 5, a high-speed CMOS camera 6, a weak light signal detection system 8, a first beam splitter 9, a semiconductor laser 10, and a solid-state laser 11; the laser polarization direction of the semiconductor laser 10 is perpendicular to the laser polarization direction of the solid-state laser 11, and a chopper 4, a first beam splitter 9, a beam combiner 3, a second beam splitter 2, and a weak light signal detection system 8 are sequentially arranged along the laser transmission direction on the laser transmission path of the semiconductor laser 10; the laser output by the solid-state laser 11 is combined with the laser output by the semiconductor laser 10 through the beam combiner 3 after passing through the structured light modulation and shaping system 1; the power meter 5 is arranged in cooperation with the first beam splitter 9; the high-speed CMOS camera 6 is arranged in cooperation with the second beam splitter 2.

[0042] The laser output by the semiconductor laser 10 has a wavelength of 630 nm.

[0043] The laser output by the solid-state laser 11 has a wavelength of 532 nm.

[0044] A filter 7 is provided at the front end of the lens of the high-speed CMOS camera 6.

[0045] The weak light signal detection system 8 includes a focusing lens 12, a detector 13, an AC amplifier 14, and a data acquisition system 15 arranged in sequence.

[0046] The working method of an on-line measurement device for the mass flow rate of powder fuel based on laser modulation according to the present invention includes the following steps:

[0047] S1: Construction and debugging of online measurement equipment;

[0048] S101: Install the semiconductor laser 10 and the solid-state laser 11. Place the chopper 4, the second beam splitter 9 and the beam combiner 3 in sequence behind the light outlet of the semiconductor laser 10. Place the beam expander, the collimator and the focusing lens of the structured light modulation and shaping system 1 in sequence behind the light outlet of the solid-state laser 10.

[0049] S102: Adjust the optical path to ensure that the laser light emitted by the semiconductor laser 10 and the laser light emitted by the solid laser 11 are in the same plane when incident on the area to be measured, so as to ensure that the powdered fuel particles in the same plane are excited.

[0050] S103: Place the filter 7 in front of the lens of the high-speed CMOS camera 6, install the lens and connect it, and then fix it to the base of the high-speed CMOS camera 6. The base is placed in a suitable position so that the height of the area to be measured is consistent with the height of the base placement platform. The lens of the high-speed CMOS camera 6 is adjusted to achieve the clearest imaging result, so as to capture the scattered image of the particles.

[0051] S104: Build a weak light signal detection system 8:

[0052] The focusing mirror 12, detector 13, AC amplifier 14 and data acquisition system 15 in the weak light signal detection system 8 are arranged as required to ensure that the focus position of the focusing mirror 12 is located at the position irradiated by the sheet laser.

[0053] S2: optical signal processing before mass flow rate measurement;

[0054] S201: The semiconductor laser 10 outputs continuous laser light;

[0055] S202: The chopper 4 rotates to modulate the continuous laser into a modulated laser with a fixed period, and generates a square wave signal with the same frequency as the modulated laser;

[0056] S203: The square wave signal is split by the second beam splitter 9 and then passes through the power meter 5 to record the optical signal information;

[0057] S204: The output laser of the solid laser 11 is modulated and shaped into a sheet laser by the structured light modulation and shaping system 1, and then combined with the modulated laser by the beam combiner 3;

[0058] S205: The combined laser beam is incident on the area to be measured;

[0059] S206: The focusing mirror 12 performs spatial filtering on the combined laser beam;

[0060] S207: The detector 13 converts the combined laser optical signal into an electrical signal;

[0061] S208: The electrical signal passes through the AC amplifier 14 to filter out the DC noise component and amplify the AC signal component;

[0062] S209: The data acquisition system 15 acquires the measurement signal and the reference signal;

[0063] S2010: The data acquisition system 15 transmits the measurement signal and the reference signal to the computer for phase-locked processing and analysis, obtains the information related to the target radiation, and converts the information related to the target radiation into radiance, which is used to correlate the particle density and flow velocity information. The purpose of suppressing the unmodulated background light noise and greatly improving the signal detection signal-to-noise ratio is achieved.

[0064] S3: Synchronous measurement of the powder fuel particle density and flow velocity;

[0065] S301: Using the extinction method to compare the relationship between the transmitted light intensity and the incident intensity of the modulated laser to measure the particle density of the powder fuel;

[0066] S302: After the sheet laser irradiates the area to be measured, use the high-speed CMOS camera 6 to capture the scattering image of the powder fuel particles;

[0067] S303: Particle flow velocity measurement:

[0068] For small particles and low-concentration regions (flow fields with a mass flow rate range below 100 g / s), measure the particle flow velocity of the powder fuel by PIV;

[0069] For high-concentration regions (dense gas-solid two-phase flow field environment, flow fields with a mass flow rate greater than or equal to 100 g / s), calculate the movement of pixel points or feature points in the image sequence between consecutive image frames by the optical flow algorithm to obtain the particle flow velocity of the powder fuel.

[0070] S4: Calibrate the on-line measurement device by the weighing method, establish a non-linear function relationship between the powder fuel particle density and flow velocity and the mass flow rate calibration by the machine learning algorithm, and obtain the instantaneous flow rate information of the powder fuel in real time.

[0071] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent conditions of the claims are intended to be included in the present invention. Any reference signs in the claims should not be regarded as limiting the claimed rights.

[0072] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A laser-modulated on-line measurement device for powder fuel mass flow rate, characterized by: The invention comprises a structured light modulation and shaping system (1), a second beam splitter (2), a beam combining mirror (3), a chopper (4), a power meter (5), a high-speed CMOS camera (6), a weak light signal detection system (8), a first beam splitter (9), a semiconductor laser (10) and a solid laser (11); the laser polarization direction of the semiconductor laser (10) is arranged perpendicular to the laser polarization direction of the solid laser (11), and the chopper (4), the first beam splitter (9), the beam combining mirror (3) and the solid laser (11) are sequentially arranged on the laser transmission path of the semiconductor laser (10) along the laser transmission direction. (3), a second beam splitter (2) and a weak light signal detection system (8); the laser output by the solid laser (11) is combined with the laser output by the semiconductor laser (10) through a beam combiner (3) after being modulated and shaped by the structured light system (1); the power meter (5) is arranged in conjunction with the first beam splitter (9); the high-speed CMOS camera (6) is arranged in conjunction with the second beam splitter (2); the weak light signal detection system (8) includes a focusing mirror (12), a detector (13), an AC amplifier (14) and a data acquisition system (15) arranged in sequence.

2. The laser-modulated powder fuel mass flow rate online measurement device according to claim 1, characterized in that: The laser wavelength output by the semiconductor laser (10) is 630 nm.

3. The laser-modulated on-line measurement device for powdered fuel mass flow rate according to claim 1, characterized in that: The laser wavelength output by the solid laser (11) is 532 nm.

4. The laser-modulated powder fuel mass flow rate online measurement device according to claim 1, characterized in that: A filter (7) is provided at the front end of the lens of the high-speed CMOS camera (6).

5. A method for operating the laser-modulated powder fuel mass flow rate online measurement device according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: S1: Construction and debugging of online measurement equipment; S2: optical signal processing before mass flow rate measurement; S3: Simultaneous measurement of powdered fuel particle density and flow rate; S301: Using the extinction method to compare the relationship between the transmitted light intensity and the incident intensity of the modulated laser, the particle density of the powdered fuel is measured; S302: After the sheet laser irradiates the area to be measured, a high-speed CMOS camera (6) is used to capture a scattered image of the powdered fuel particles; S303: Particle flow rate measurement: For low concentration areas, the particle velocity of the powdered fuel was measured by PIV; For high-concentration areas, the movement of pixels or feature points between consecutive image frames in the image sequence is calculated using an optical flow algorithm to obtain the particle flow rate of the powdered fuel; S4: The online measuring device is calibrated using the weighing method to establish a calibration relationship between the density and flow velocity of the powder fuel particles and the mass flow rate, and to obtain the instantaneous flow rate information of the powder fuel in real time.

6. The method according to claim 5, characterized in that: The S2 comprises the following steps: S201: The semiconductor laser (10) outputs continuous laser light; S202: The chopper (4) rotates to modulate the continuous laser into a modulated laser with a fixed period, and generates a square wave signal with the same frequency as the modulated laser; S203: The square wave signal is split by the second beam splitter (9) and then passes through the power meter (5) to record the optical signal information; S204: The output laser of the solid laser (11) is modulated and shaped into a sheet laser by the structured light modulation and shaping system (1), and then combined with the modulated laser by the beam combiner (3); S205: The combined laser beam is incident on the area to be measured; S206: The focusing mirror (12) performs spatial filtering on the combined laser beam; S207: The detector (13) converts the combined laser light signal into an electrical signal; S208: The electrical signal passes through an AC amplifier (14) to filter out DC noise components and amplify AC signal components; S209: The data acquisition system (15) acquires the measurement signal and the reference signal; S2010: The data acquisition system (15) transmits the measurement signal and the reference signal to the computer for phase-locked processing and analysis to obtain target radiation related information, and converts the target radiation related information into radiation brightness for correlating particle density and velocity information.

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