Powder fuel mass flow rate online measuring device and method based on laser modulation

Abstract

The invention discloses a powder fuel mass flow rate online measuring device and method based on laser modulation, and belongs to the technical field of laser spectrum application. The semiconductor laser and the solid laser are vertically arranged, and a chopper, a first beam splitter, a beam combiner, a second beam splitter and a weak light signal detection system are arranged on a laser transmission path of the semiconductor laser; laser output by the solid laser passes through the structured light modulation and shaping system and then is combined with laser of the semiconductor laser through the beam combiner; the power meter is matched with the first beam splitter; and the high-speed CMOS camera is matched with the second beam splitter. The method comprises the following steps: setting up and debugging the device; optical signal processing; powder fuel particle density and flow velocity are measured synchronously; and calibrating an online measuring device, establishing a calibration relationship between the density and the flow velocity of the powder fuel particles and the mass flow rate, and obtaining instantaneous flow rate information of the powder fuel in real time. According to the invention, the signal-to-noise ratio of the detection signal is improved, and the real-time high-precision measurement of the mass flow rate under the high-speed dense gas-solid two-phase background is realized.

Description

Technical Field

[0001] The invention relates to an online measurement device for mass flow rate of powdered fuel based on laser modulation and a method thereof, belonging to the technical field of laser spectrum application. Background Art

[0002] The powder engine is a new type of engine that uses high-energy metal or boron powder as fuel. It has a wide range of applications in the new generation of long-range air-to-air missiles, air-to-ground missiles and air defense missiles. It is based on the powder fuel entering the combustion chamber in the form of gas-solid two-phase combustion under the action of fluidizing gas to generate thrust. The powder fuel supply system is the core component of the powder engine. The online real-time high-precision measurement of the powder fuel mass flow rate is the key to ensure that the powder engine has adjustable thrust and multi-pulse starting.

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

[0004] The current measurement methods of powder fuel mass flow rate are mainly divided into direct measurement method and indirect measurement method in terms of measurement form, which have the following limitations:

[0005] 1. Direct measurement method (such as Coriolis flow meter and weighing method):

[0006] 1. Coriolis flowmeter has nothing to do with fluid properties. Although it has high measurement accuracy and does not affect the flow field, it is widely used for mass flow measurement of gas, liquid and gas-liquid two-phase, but it is not suitable for dense gas-solid two-phase flow measurement.

[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] 2. 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 methods, which can only obtain the average mass flow rate of powder fuel over a period of time, and cannot achieve online flow rate measurement, making it difficult to meet the needs 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 the cross-correlation method, this method is affected by the laser transmission and detection in a dense gas-solid two-phase flow environment, resulting in a large variation in the detection signal, strong noise, and low signal-to-noise ratio, and thus the measurement accuracy cannot be guaranteed. Summary of the invention

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

[0012] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: an online measurement device for the mass flow rate of powdered fuel 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 being modulated and shaped by the structured light; 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 630nm.

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

[0015] A filter is arranged 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] A working method of a powder fuel mass flow rate online measurement device based on laser modulation of the present invention comprises 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 recorded with a power meter;

[0023] S204: The output laser of the solid laser is modulated and shaped into a sheet laser by a 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 is filtered out through an AC amplifier to remove 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: Synchronous measurement of powder 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 tested, a high-speed CMOS camera is used to capture a scattered image of the powder fuel particles;

[0033] S303: Particle flow rate measurement:

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

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

[0036] S4: The online measuring device is calibrated by the weighing method to establish the calibration relationship between the density and flow velocity of the powder fuel particles and the mass flow rate, and the instantaneous flow rate information of the powder fuel is obtained 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 phase-locked amplification methods to improve the signal-to-noise ratio of the detection signal, obtain target radiation-related information, realize synchronous measurement of particle density and flow velocity based on the extinction method, particle image velocimetry and optical flow method, and adopts a machine learning algorithm to establish a nonlinear functional relationship between mass flow rate and particle density and flow velocity, thus solving the problem of real-time and high-precision measurement of mass flow rate in a high-speed dense gas-solid two-phase background. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0040] The technical solution of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] A powder fuel mass flow rate online measurement device based on laser modulation comprises 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 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 combiner 3, the second beam splitter 2 and the weak light signal detection system 8 are arranged in sequence on the laser transmission path of the semiconductor laser 10 along the laser transmission direction; the laser output by the solid 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 conjunction with the first beam splitter 9; and the high-speed CMOS camera 6 is arranged in conjunction with the second beam splitter 2.

[0042] The laser wavelength output by the semiconductor laser 10 is 630 nm.

[0043] The laser wavelength output by the solid laser 11 is 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 which are arranged in sequence.

[0046] A working method of a powder fuel mass flow rate online measurement device based on laser modulation of the present invention comprises 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, and 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; and 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 powder 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 on 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 tested is consistent with the height of the base placement platform, and adjust the lens of the high-speed CMOS camera 6 to make the lens imaging result reach the clearest state, 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 focal 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 light 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 target radiation related information, and converts the target radiation related information into radiation brightness for associating particle density and flow rate information, thereby suppressing unmodulated background light noise and significantly improving the signal-to-noise ratio of signal detection.

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

[0065] 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;

[0066] S302: After the sheet laser irradiates the area to be tested, a high-speed CMOS camera 6 is used to capture a scattered image of the powder fuel particles;

[0067] S303: Particle flow rate measurement:

[0068] For small particles and low concentration areas (flow fields with mass flow rate range below 100 g / s), the particle flow rate of powder fuel is measured by PIV;

[0069] For high-concentration areas (dense gas-solid two-phase flow field environment, flow field with a mass flow rate greater than or equal to 100 g / s), the movement of pixels or feature points in the image sequence between consecutive image frames is calculated using the optical flow algorithm to obtain the particle flow rate of the powdered fuel.

[0070] S4: The weighing method is used to calibrate the online measurement device, and the machine learning algorithm is used to establish the nonlinear functional relationship between the powder fuel particle density and flow velocity and the mass flow rate calibration, so as to obtain the instantaneous flow rate information of the powder fuel in real time.

[0071] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0072] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An online measurement device for mass flow rate of powdered fuel based on laser modulation, characterized in that: 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-state laser (11); the laser polarization direction of the semiconductor laser (10) is arranged perpendicular to the laser polarization direction of the solid-state laser (11); the chopper (4), the first beam splitter (9), the beam combining mirror (3), the second beam splitter (2) and the weak light signal detection system (8) are arranged in sequence on the laser transmission path of the semiconductor laser (10) along the laser transmission direction; the laser output by the solid-state laser (11) is combined with the laser output by the semiconductor laser (10) through the beam combining mirror (3) after passing through the structured light modulation and shaping system (1); the power meter (5) is arranged in conjunction with the first beam splitter (9); and the high-speed CMOS camera (6) is arranged in conjunction with the second beam splitter (2).

2. The on-line measurement device for mass flow rate of powdered fuel based on laser modulation according to claim 1, characterized in that: The laser wavelength output by the semiconductor laser (10) is 630 nm.

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

4. The on-line measurement device for mass flow rate of powdered fuel based on laser modulation according to claim 1, characterized in that: A filter (7) is arranged at the front end of the lens of the high-speed CMOS camera (6).

5. The on-line measurement device for mass flow rate of powdered fuel based on laser modulation according to claim 1, characterized in that: The weak light signal detection system (8) comprises a focusing mirror (12), a detector (13), an AC amplifier (14) and a data acquisition system (15) which are arranged in sequence.

6. A working method of the on-line measurement device for mass flow rate of powdered fuel based on laser modulation according to any one of claims 1 to 5, 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: Synchronous measurement of powder 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 tested, a high-speed CMOS camera (6) is used to capture a scattered image of the powder fuel particles; S303: Particle flow rate measurement: For low concentration areas, the particle velocity of the powdered fuel is 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 by the weighing method to establish the calibration relationship between the density and flow velocity of the powder fuel particles and the mass flow rate, and the instantaneous flow rate information of the powder fuel is obtained in real time.

7. The method according to claim 6, 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 a second beam splitter (9) and then passes through a power meter (5) to record 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 a 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 associating particle density and velocity information.

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