CN214539124U - Two-dimensional rainbow refraction device for measuring liquid drops in plane - Google Patents
Two-dimensional rainbow refraction device for measuring liquid drops in plane Download PDFInfo
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Abstract
The utility model discloses a two-dimentional rainbow refraction device of liquid drop in measurement plane: the laser light source emitting and atomized liquid drop generating system comprises a laser, a light beam modulating element and an atomizing device, wherein laser beams emitted by the laser are modulated into a vertically polarized light source through the light beam modulating element and irradiate atomized liquid drops generated by the atomizing device to form a rainbow signal of the liquid drops; the light beam modulation element sequentially comprises a vertical polaroid, a plano-concave cylindrical lens and a plano-convex cylindrical lens; the rainbow signal acquisition system sequentially comprises a convex lens, a horizontal slit diaphragm, a cylindrical lens and a digital camera, and is used for separately imaging and recording rainbow signals of atomized liquid drops with different heights and different horizontal positions to obtain a two-dimensional rainbow image; and the rainbow signal processing system is used for processing the two-dimensional rainbow image to obtain the position, the particle size and the refractive index of the atomized liquid drop in the plane to be detected. The device has the characteristics of non-contact, two-dimension, high precision, in-situ online and the like, and can analyze the fluid multiphase flow related to liquid drops.
Description
Technical Field
The utility model relates to a gas-liquid two-phase flow measurement field, concretely relates to can measure two-dimentional rainbow refraction measuring device of in-plane atomizing liquid drop two-dimentional position, particle diameter and refracting index.
Background
Liquid atomization is a gas-liquid two-phase flow phenomenon widely existing in the industrial fields of energy, power, environment and the like, such as gas-liquid mixing and absorption in liquid fuel atomization evaporation combustion, desulfurization and denitrification spraying equipment and the like. Accurate measurement of parameters such as gas-liquid two-phase flow field velocity, particle size, concentration, temperature, components and the like is helpful for people to master a complex gas-liquid two-phase flow mechanism, thereby guiding industrial optimization design and manufacture.
Various droplet measuring methods have been invented and applied by researchers, and may be mainly classified into a mechanical contact method, an electromagnetic field method, and an optical measuring method (including infrared rays, visible rays, X-rays, and the like). Although the principle and operation of the traditional mechanical contact method are simpler, the original distribution structure of the flow field is always damaged inevitably by the contact measurement mode. The optical measurement method has no interference on the original gas-liquid two-phase flow, generally has the advantages of high measurement precision, real-time and rapid speed, large information quantity and the like, and is widely applied to various research fields in recent years. The measurement methods of macroscopic parameters such as the penetration depth of the spray, the spray velocity, the atomization cone angle and the like are already mature. However, in practical research, it is desirable to further understand the atomization condition of the liquid drops in the flow field, particularly the evaporation rate of the liquid drops; under certain conditions of chemical composition, it depends mainly on two parameters of contact surface area with ambient environment and droplet temperature. Therefore, it is necessary to develop an optical measurement method for simultaneously measuring the droplet size, the temperature distribution and the evolution law thereof on line.
Optical methods commonly used in recent years to measure droplet size are: high-speed photography, a Malvern particle size analyzer, a laser Mie scattering technique, a laser-induced fluorescence method, a digital holography technique, an interference particle imaging technique, and the like; methods that can be used to measure the temperature of the droplets are: two-color laser induced fluorescence, laser induced phosphorescence, raman scattering, and the like. Compared with the measurement method, the rainbow refraction technology has the characteristics of simultaneously and accurately measuring the particle size, the temperature and the evolution rule of atomized liquid drops, and is rapidly developed in the field of atomized gas-liquid two-phase flow in recent years. When the liquid drop is irradiated by monochromatic laser, the second-order scattered light of the liquid drop interferes with each other to form gradually attenuated light and dark alternate fringes, which are called Airy structures. The position and the shape of the structure are respectively sensitive to liquid drop characteristic parameters such as the refractive index and the particle size of the liquid drop. Therefore, the rainbow signal is inverted, the particle size and the refractive index of the liquid drop are obtained simultaneously, and parameters such as the temperature or the concentration of the liquid drop related to the refractive index of the liquid drop are deduced.
Roth et al first proposed a standard rainbow refraction method for studying monodisperse droplets. But the high-frequency ripple structure, the non-spherical shape of the liquid drop and the like can greatly influence the measurement precision of the technology. On the basis of this, Van Beeck et al further proposed a full-field rainbow refraction method for the measurement of polydisperse droplet populations. By prolonging the exposure time and enlarging the clear aperture, thousands of smooth rainbow with certain particle size distribution liquid drop groups are recorded at the same time, and further the information such as average refractive index and particle size distribution of the liquid drop groups is obtained. The high-frequency ripple structure which is particularly sensitive to the particle size is eliminated by the polydisperse liquid drops; meanwhile, the influence of a few non-spherical liquid drops is smoothed because a synthetic rainbow diagram of thousands of liquid drops is recorded. The whole-field rainbow refraction technology solves the problem that the measurement is influenced by a high-frequency ripple structure and non-spherical liquid drops, and is widely applied to diagnosis of spray evaporation and combustion. Although the measurement object of the full-field rainbow refraction technology is an atomized liquid drop group, the measurement object still belongs to the category of 'single-point' zero-dimensional measurement like the standard rainbow refraction technology. Wu scholarly and the like provide a one-dimensional rainbow refraction method, can simultaneously obtain the parameters of liquid drops at different heights on a measuring line, realizes the breakthrough from zero-dimensional measurement to one-dimensional measurement, and provides a beneficial tool for continuously tracking the particle size and temperature evolution of the liquid drops. Wu Yingchun et al propose a phase rainbow refraction method based on a one-dimensional rainbow refraction method, which can measure the refractive index, the particle size and the tiny change of the liquid drop, and further measure the heat and mass transfer parameters such as the transient evaporation rate of the liquid drop. However, the measurement area of these techniques is limited to a single point or a one-dimensional line segment, and the particle size and refractive index of the liquid drop in a two-dimensional space, which are widely existed in real conditions, cannot be obtained.
The rainbow refraction technology needs to be further developed to be two-dimensional or even three-dimensional, and has important significance for more comprehensively and deeply researching the spraying mechanism.
SUMMERY OF THE UTILITY MODEL
The utility model aims at overcoming current single-point one-dimensional rainbow refraction method and being limited to single-point one-dimensional measuring defect only, providing a two-dimentional rainbow refraction device and method of measuring the liquid drop in the plane, can measure two-dimentional position, particle diameter and the refracting index of atomizing liquid drop in the plane, can the analysis relate to the heterogeneous stream of fluid of liquid drop, realize the on-line measuring of processes such as fuel atomization field, liquid drop evaporation burning, have characteristics such as two-dimensional plane, high accuracy and non-contact.
The utility model discloses a solve the concrete technical scheme that above-mentioned technical problem adopted and be:
a two-dimensional rainbow refraction device for measuring in-plane droplets, comprising:
the laser sheet light source emission and atomized liquid drop generation system comprises a laser, a light beam modulation element and an atomization device; laser beams emitted by the laser are modulated into a vertically polarized light source by a light beam modulation element, and atomized liquid drops generated in a plane to be detected by the atomization device are irradiated to form a rainbow signal of the liquid drops; the light beam modulation element sequentially comprises a vertical polaroid, a plano-concave cylindrical lens and a plano-convex cylindrical lens;
the rainbow signal acquisition system sequentially comprises a convex lens, a horizontal slit diaphragm, a cylindrical lens and a digital camera, and is used for separately imaging and recording rainbow signals of atomized liquid drops with different heights and different horizontal positions to obtain a two-dimensional rainbow image, and transmitting the two-dimensional rainbow image to the rainbow signal processing system;
and the rainbow signal processing system is used for processing the two-dimensional rainbow image to obtain the position, the particle size and the refractive index of the atomized liquid drop in the plane to be detected.
The laser beam emitted by the laser device is converted into a vertical linear polarization laser beam after passing through the vertical polaroid, and then expanded into a vertical sheet light source by the plano-concave cylindrical lens and the plano-convex cylindrical lens for irradiating atomized liquid drops in a plane to be measured. The laser is a continuous laser or a pulse laser; the atomization device is a pneumatic type or pressure type atomization nozzle. In particular, a continuous laser or a pulse laser for generating a coherent light beam with adjustable intensity and good beam characteristics; the atomizing device is used for spraying solid cone atomized liquid drop groups.
Preferably, the continuous laser is a semiconductor laser with adjustable light intensity of 0-5000 mW, the wavelength is a visible light wave band of 400-760 nm, and the beam waist radius is 0.4-2 mm; the pulse laser is a solid laser with adjustable single-pulse energy of 0mJ to 100mJ, the pulse width is between 1ns and 500ns, the wavelength is a visible light wave band of 400nm to 760nm, and the beam waist radius is between 0.4mm and 2 mm.
Preferably, the focal length of the plano-concave cylindrical lens is-20 mm to-5 mm, and the focal length of the plano-convex cylindrical lens is 50mm to 200 mm; the height of the vertically polarized light sheet is not less than 10mm, and the thickness is not more than 2 mm.
The horizontal slit diaphragm is arranged at the back focal length of the convex lens, so that only scattered light which vertically enters the convex lens can pass in the height direction, and the scattered light in other directions is filtered, so that rainbow signals of atomized liquid drops with different heights are separately imaged and recorded on different rows of pixels of the digital camera, and the rainbow signals of atomized liquid drops with different horizontal positions are separately imaged and recorded on different columns of pixel blocks of the digital camera in the form of stripe blocks; and a vertically arranged cylindrical lens is arranged behind the horizontal slit diaphragm and used for adjusting the width of the rainbow signal in the horizontal direction on the digital camera.
The width of the horizontal slit diaphragm is variable and is 0.1mm to 10 mm; the diameter of the convex lens is 50mm to 200mm, and the focal length is 50mm to 250 mm; the cylindrical lens is a vertical plano-concave cylindrical lens, and the focal length is-200 mm to-5 mm; the digital camera is an area-array camera (such as CCD or CMOS), the pixel range is 1M to 16M, the record scattering angle range is 6 degrees to 20 degrees, the angular resolution is not less than 0.002 degrees, the exposure time is adjustable within 1 mus to 1000ms, and the exposure time of the camera can be selectively adjusted according to different measurement objects and measurement conditions, so that the optimal measurement effect is achieved.
The rainbow signal processing system comprises a computer and a synchronous controller; the computer is connected with the laser and the digital camera through the synchronous controller and synchronously controls the laser and the digital camera, including controlling the switch and the intensity of the laser and the switch and the exposure time of the digital camera (when the laser is a pulse laser, the frequency of the pulse light and the digital camera is also synchronously controlled); and processing the two-dimensional rainbow image to obtain the position, the particle size and the refractive index of the atomized liquid drop in the plane to be detected.
For the atomized liquid drop in the plane to be measured, the position of the atomized liquid drop on the plane perpendicular to the optical axis is recorded and is proportional to the position recorded on the digital camera, and the position of the liquid drop plane can be determined by calibrating the relationship between the atomized liquid drop and the liquid drop.
The two-dimensional rainbow refraction method for measuring the liquid drop in the plane by using the device comprises the following steps:
(1) calibrating two-dimensional scattering angles of different vertical measurement line positions in a plane to be measured by the two-dimensional rainbow refraction measuring device;
(2) opening the atomization device, and adjusting the atomized liquid drop group to a stable working state;
(3) starting a laser, modulating a laser beam emitted by the laser by a polarizing film, a plano-concave cylindrical lens and a plano-convex cylindrical lens, and irradiating atomized liquid drops in a plane to be detected in a mode of being vertical to a polarizing film light source to form a rainbow signal;
(4) the rainbow signals are collected by the convex lens, converged and propagated backwards, and are separately imaged on different rows of pixels of the digital camera through the horizontal slit diaphragm and the vertical plano-concave cylindrical lens in sequence, and the rainbow signals of the atomized droplets at different horizontal positions are separately imaged on different columns of pixel blocks of the digital camera in the form of stripe blocks;
(5) adjusting the width of a horizontal slit diaphragm and the position of a vertical plano-concave cylindrical lens, and controlling the height and the position of an rainbow streak block until a clear two-dimensional rainbow image generated by atomized liquid drops in a plane to be measured with proper size is obtained;
(6) and (4) combining the two-dimensional scattering angle calibration result, processing the recorded two-dimensional rainbow image by the rainbow signal processing system to obtain the position, the particle size and the refractive index of the atomized liquid drop in the plane to be detected.
The two-dimensional scattering angle calibration in the step (1) is to obtain the corresponding relation between the scattering angle at different positions in the plane to be measured and the pixel position of the digital camera, and the calibration method is as follows:
(1-1) producing a stream of monodisperse droplets of known particle size D and refractive index n using a monodisperse droplet generation system;
(1-2) in the incident direction of a laser sheet light source, sequentially moving the monodisperse droplet flow from the edge of a plane to be measured to different vertical measurement line positions by using a three-dimensional displacement table, and acquiring and recording a calibration experiment rainbow signal for calibrating a two-dimensional scattering angle through a rainbow signal acquisition system after being irradiated by a vertical polarizer light source, wherein the calibration experiment rainbow signal is a function of scattering intensity distribution on the pixel position of a digital camera;
(1-3) calculating an accurate calibration theoretical rainbow signal by utilizing Mie's theory simulation according to the known particle diameter D and the refractive index n of the droplet flow, wherein the calibration theoretical rainbow signal is a function of scattering intensity distribution relative to a scattering angle;
(1-4) matching the calibration experiment rainbow signals collected at the positions of the vertical measurement lines with the calibration theory rainbow signals in a fitting manner by combining a global optimization algorithm, and sequentially obtaining the calibration relation between the scattering angle and the pixel position at each vertical measurement line;
and (1-5) further adopting an interpolation method to fit to obtain a scattering angle-pixel position calibration relation at the positions of other vertical measurement lines, namely completing two-dimensional scattering angle calibration.
Wherein, in the step (1-1), the monodisperse droplet generation system comprises a monodisperse droplet generator, a high-pressure injection pump, a signal generator, an adapter and the like.
The method for processing the recorded two-dimensional rainbow image in the step (6) comprises the following steps:
(6-1) identifying and positioning the position (x) of the rainbow signal of each liquid drop in the measuring area on the digital camera according to the recorded two-dimensional rainbow imager，yr)；
For the atomized liquid drop in the plane to be measured, the position on the plane perpendicular to the optical axis through the liquid drop is (x)s，ys) The light transmission matrix from the liquid drop to the digital camera in the horizontal and vertical directions is
And
for angles in the horizontal and vertical directions of (theta)s，
) The position (x) recorded on the digital camera after the scattered light near the geometric rainbow angle passes through the rainbow signal acquisition systemr，yr) Can be expressed as:
in the implementation of the light transmission matrix system, AxNot equal to 0 to ensure the same height ysDifferent horizontal positions xsThe rainbow signal of the liquid drop can be separated in the horizontal direction of the digital camera; a. theyNot equal to 0 to ensure that it is in the same horizontal position xsDifferent height ysThe rainbow signals of the liquid drops can be separated in the vertical direction of the digital camera;
(6-2) Transmission matrix parameter A in combination with Rainbow signal acquisition systemx、Ay、Bx、ByAngle (theta) of sum and rainbow signal in horizontal and vertical directionss，
) The plane position (x) of each liquid drop in the plane to be measured can be calculateds，ys) Wherein x iss＝(xr-Bxθs)/Ax，
(6-3) combining a pre-two-dimensional scattering angle calibration relation, and simultaneously and iteratively calculating a light intensity linear equation of each liquid drop rainbow signal in the measurement area on a computer:
wherein, Ir(theta) Rainbow signal collected for experiment, If(D, n, theta) is an inversion fitted rainbow signal, theta is a scattering angle of the rainbow signal, D is the diameter of the liquid drop, and n is the refractive index;
and (6-4) when the difference between the rainbow signals acquired through the experiment and the rainbow signals fitted by inversion is smaller than a preset threshold value, finishing the inversion, and thus obtaining the position, the particle size and the refractive index of each measured atomized droplet in the plane to be measured.
Compared with the prior art, the beneficial effects of the utility model reside in that: the defect that the existing single-point/one-dimensional rainbow refraction method is only limited to single-point/one-dimensional measurement is overcome, and the two-dimensional rainbow refraction measuring device is provided. The device can simultaneously measure the positions, the particle sizes and the refractive indexes of atomized liquid drops at different positions in a plane to be measured; through the time continuous measurement, the two-dimensional distribution evolution law of the key parameters can be further obtained. The device of the utility model has the characteristics of simple structure and being suitable for industrial on-line application and the like.
Drawings
FIG. 1 is a schematic diagram of the overall structure and optical path system of an embodiment of the two-dimensional rainbow refraction measuring apparatus of the present invention;
fig. 2 is an enlarged schematic structural diagram of the atomized liquid droplet group and the liquid droplet rainbow signal image in the present invention;
FIG. 3 is a schematic diagram of a monodisperse droplet generation system used in a two-dimensional scattering angle calibration process;
the system comprises a laser 1, a laser 2, a vertical polarizing film, a plano-concave cylindrical lens 3, a plano-convex cylindrical lens 4, a laser sheet light source 5, a laser light source 6, a plane to be detected 7, atomized liquid drops 8, a rainbow signal 9, a convex lens 10, a horizontal slit diaphragm 11, a vertical plano-concave cylindrical lens 12, a digital camera 13, a collected rainbow signal 14, a computer 15, a synchronous controller 16, an atomizing device 17, a measuring area 18, a two-dimensional rainbow image 19, a monodisperse liquid drop stream 20, a monodisperse liquid drop generator 21, a three-dimensional displacement table 22, a connector 23, a high-pressure injection pump 24 and a signal generator.
Detailed Description
The following provides a further description of embodiments of the present invention with reference to the accompanying drawings.
As shown in fig. 1, a two-dimensional rainbow refraction measuring apparatus includes:
a. a laser beam emitted by a laser 1 is modulated into a laser sheet light source 5 with vertical polarization through a beam modulation element, and irradiates atomized liquid drops 7 generated by an atomization device 16 in a plane 6 to be measured to form a rainbow signal 8. The laser sheet light source emission and atomized liquid drop generation system comprises three parts:
the laser 1 is used for generating coherent light beams with adjustable intensity and good light beam characteristics; the semiconductor laser 1 of the embodiment is a light intensity adjustable laser of 0mW to 2000mW, the wavelength is 532nm, and the beam waist radius is 1 mm;
the light beam modulation element comprises a vertical polarizer 2, a plano-concave cylindrical lens 3 and a plano-convex cylindrical lens 4, and is used for modulating an emergent laser beam into a vertically polarized light sheet 5; the focal length of the plano-concave cylindrical lens 3 is minus 5mm, and the focal length of the plano-convex cylindrical lens 4 is 200 mm; the laser sheet light source 5 is propagated in parallel, and has a height of 41mm and a thickness of 1 mm.
The atomizing device 16 is used for ejecting solid cone atomized liquid droplet group, and in this embodiment, is a pneumatic nozzle.
b. And the rainbow signal acquisition system is used for separately recording rainbow signals 8 generated by the atomized liquid drops 7 at different positions in the plane 6 to be detected on the digital camera 12 through the signal acquisition system to obtain a two-dimensional rainbow image 18. The rainbow signal collecting system includes a convex lens 9, a horizontal slit 10, a vertical plano-concave cylindrical lens 11, and a digital camera 12. Rainbow signals 8 of the atomized droplets 7 at different positions in the plane 6 to be measured are collected by the convex lens 9 and converged and then propagated backward. The convex lens 9 is provided with a horizontal slit diaphragm 10 at the back focal length, and the horizontal slit diaphragm 10 enables only the scattered light which vertically enters the convex lens to pass through in the height direction, so that the scattered light in other height directions is filtered. A vertical plano-concave cylindrical lens 11 is placed between the horizontal slit diaphragm 10 and the digital camera 12 for adjusting the width of the rainbow signal in the horizontal direction without affecting the propagation of the collected rainbow signal 13 in the vertical direction. Rainbow signals 8 of atomized droplets 7 of different heights are separately imaged on different rows of pixels of the digital camera 12; the rainbow signals 8 of the atomized droplets 7 at different horizontal positions are separately imaged in the form of striped blocks on different columns of blocks of pixels of the digital camera 12. The diameter of the convex lens 9 is 100mm, and the focal length is 150 mm; the width of the horizontal slit diaphragm 10 is variable and is 0.1mm to 2 mm. The digital camera 12 is an area-array CMOS camera, and has 8M pixels. The acquisition system recorded a scatter angle range of 15 ° with an angular resolution of 0.002 °.
And the rainbow signal processing system is used for sequentially identifying, positioning and inverting the two-dimensional rainbow image 18 to obtain the position, the particle size and the refractive index of the atomized liquid drop 7 in the plane 6 to be detected. The rainbow signal processing system comprises a computer 14 and a synchronization controller 15. The computer 14 is connected to and synchronously controls the laser 1 and the digital camera 12 through the synchronous controller 15, including controlling the switching and intensity of the laser 1 and the switching and exposure time of the digital camera 12 (when the laser 1 is a pulse laser, the frequency of the pulse light and the digital camera 12 are also synchronously controlled).
The two-dimensional rainbow refraction method for measuring the liquid drop in the plane by using the device comprises the following steps:
(1) the two-dimensional scattering angle calibration of vertical measurement lines at different positions is carried out on the two-dimensional rainbow refraction measurement device, and the calibration method of the embodiment comprises the following steps:
as shown in fig. 3, a stream 19 of monodisperse droplets of known particle size D and refractive index n is generated using a monodisperse droplet generation system consisting of a monodisperse droplet generator 20, a high pressure syringe pump 23, a signal generator 24, an adapter 22, etc. In the incident direction of the laser sheet light source 5, the three-dimensional displacement table 21 is utilized to sequentially move the monodisperse droplet flow 19 from the edge of the plane to be measured to different vertical measurement line positions, after the laser sheet light source 5 which is vertically polarized irradiates, the laser sheet light source is collected and recorded into a calibration experiment rainbow signal for calibrating the two-dimensional scattering angle through a rainbow signal collection system, and the calibration experiment rainbow signal is a function of the scattering intensity distribution about the pixel position of the digital camera. And calculating an accurate calibration theoretical rainbow signal by utilizing the Mie's theoretical simulation according to the known particle diameter D and the refractive index n of the droplet flow, wherein the calibration theoretical rainbow signal is a function of the scattering intensity distribution on the scattering angle. And fitting and matching the calibration experiment rainbow signals collected at the positions of the vertical measurement lines and the calibration theory rainbow signals by combining a global optimization algorithm, and sequentially obtaining the calibration relation between the scattering angle and the pixel position at each vertical measurement line. And further adopting an interpolation method to fit to obtain the scattering angle-pixel position calibration relation at the positions of other vertical measurement lines, namely completing the two-dimensional scattering angle calibration.
(2) Turning on the atomizer 16 shown in fig. 2, and adjusting the atomized droplet group to a stable working state;
(3) the method comprises the following steps that a laser 1 is started, laser beams emitted by the laser 1 are modulated by a vertical polarizing film 2, a plano-concave cylindrical lens 3 and a plano-convex cylindrical lens 4, then are irradiated to atomized liquid drops 7 in a plane 6 to be measured in a mode of a vertical polarizing film light source 5, and rainbow signals 8 of the liquid drops 7 at different plane positions are collected by a rainbow signal collecting system;
(4) adjusting the width of the horizontal slit diaphragm 10 and the position of the vertical plano-concave cylindrical lens 11, and controlling the height and the position of the rainbow streak block until a clear and appropriate-sized two-dimensional rainbow image 18 generated by atomized liquid droplets in a measurement area 17 as shown in fig. 2 is obtained;
(5) opening the digital camera 12, and separately imaging rainbow signals 8 of atomized droplets 7 at different positions in the plane 6 to be measured on pixel blocks of different rows and columns of the digital camera 12 in the form of stripe blocks;
(6) the rainbow signal processing system sequentially identifies, positions and inverts the rainbow signals 13 of the liquid drops recorded in the two-dimensional rainbow image 18 to obtain the positions, the particle sizes and the refractive indexes of the liquid drops;
from the recorded two-dimensional rainbow image 18, the image identifies the position (x) of the rainbow signal of each droplet on the digital camera within the positioning measurement area 17r，yr)；
Wherein, for the atomized liquid drop in the plane to be measured, the position of the atomized liquid drop on the plane perpendicular to the optical axis through the liquid drop is recorded as (x)s，ys) The light transmission matrix from the liquid drop to the digital camera in the horizontal and vertical directions is
And
for angles in the horizontal and vertical directions of (theta)s，
) The position (x) recorded on the digital camera after the scattered light near the geometric rainbow angle passes through the rainbow signal acquisition systemr，yr) Can be expressed as:
in the implementation of the light transmission matrix system, AxNot equal to 0 to ensure the same height ysDifferent horizontal positions xsThe rainbow signal of the liquid drop can be separated in the horizontal direction of the digital camera; a. theyNot equal to 0 to ensure that it is in the same horizontal position xsDifferent height ysThe rainbow signals of the liquid drops can be separated in the vertical direction of the digital camera;
transmission matrix parameter A in combined rainbow signal acquisition systemx、Ay、Bx、ByAngle (theta) of sum and rainbow signal in horizontal and vertical directionss，
) The planar position (x) of each droplet within the measurement region 17 can be calculateds，ys) Wherein x iss＝(xr-Bxθs)/Ax，
On the basis, a two-dimensional scattering angle calibration relation is combined in advance, and a linear equation of the light intensity of each liquid drop rainbow signal in the measurement area 17 is simultaneously and iteratively calculated on the computer 14:
the particle size and the refractive index of each liquid drop in the measurement area 17 are obtained through inversion; through time-continuous measurement, the two-dimensional distribution evolution law of key parameters of the atomized liquid drop group can be obtained.
In addition to the above embodiments, the technical features or technical data of the present invention can be selected and combined again within the scope disclosed in the claims and the specification of the present invention to constitute new embodiments, which can be realized by those skilled in the art without creative efforts, and therefore, the embodiments of the present invention not described in detail should be regarded as specific embodiments of the present invention and within the protection scope of the present invention.
Claims (7)
1. A two-dimensional rainbow refraction device for measuring in-plane droplets, the device comprising:
the laser sheet light source emission and atomized liquid drop generation system comprises a laser, a light beam modulation element and an atomization device; laser beams emitted by the laser are modulated into a vertically polarized light source by a light beam modulation element, and atomized liquid drops generated in a plane to be detected by the atomization device are irradiated to form a rainbow signal of the liquid drops; the light beam modulation element sequentially comprises a vertical polaroid, a plano-concave cylindrical lens and a plano-convex cylindrical lens;
the rainbow signal acquisition system sequentially comprises a convex lens, a horizontal slit diaphragm, a cylindrical lens and a digital camera, and is used for separately imaging and recording rainbow signals of atomized liquid drops with different heights and different horizontal positions to obtain a two-dimensional rainbow image, and transmitting the two-dimensional rainbow image to the rainbow signal processing system;
and the rainbow signal processing system is used for processing the two-dimensional rainbow image to obtain the position, the particle size and the refractive index of the atomized liquid drop in the plane to be detected.
2. A two-dimensional rainbow refraction device of droplets in a measurement plane as defined in claim 1 wherein said laser is a continuous laser or a pulsed laser; the atomization device is a pneumatic type or pressure type atomization nozzle.
3. A two-dimensional rainbow refraction device of droplets in a measurement plane as defined in claim 2 wherein said continuous laser is a semiconductor laser with adjustable intensity from 0mW to 5000mW, wavelength from 400nm to 760nm in the visible band, beam waist radius from 0.4mm to 2 mm; the pulse laser is a solid laser with adjustable single-pulse energy of 0mJ to 100mJ, the pulse width is between 1ns and 500ns, the wavelength is a visible light wave band of 400nm to 760nm, and the beam waist radius is between 0.4mm and 2 mm.
4. A two-dimensional rainbow refraction device of droplets in a measurement plane as defined in claim 1 wherein said plano-concave cylindrical lenses have a focal length of-20 mm to-5 mm and said plano-convex cylindrical lenses have a focal length of 50mm to 200 mm; the height of the vertically polarized light sheet is not less than 10mm, and the thickness of the vertically polarized light sheet is not more than 2 mm.
5. The apparatus of claim 1, wherein the convex lens has a horizontal slit diaphragm at the back focal length, so that only the scattered light from the convex lens incident vertically in the height direction can pass through the diaphragm, thereby filtering the scattered light in other directions, so that the rainbow signals of atomized droplets with different heights can be separately imaged and recorded on different rows of pixels of the digital camera, and the rainbow signals of atomized droplets with different horizontal positions can be separately imaged and recorded on different columns of pixel blocks of the digital camera in the form of striped blocks; and a vertically-arranged cylindrical lens is arranged behind the horizontal slit diaphragm and used for adjusting the width of the rainbow signal in the horizontal direction on the digital camera.
6. A two-dimensional rainbow refraction device of liquid droplets in the measurement plane as defined in claim 5 wherein said horizontal slit diaphragm has a variable width of 0.1mm to 10 mm; the diameter of the convex lens is 50mm to 200mm, and the focal length is 50mm to 250 mm; the cylindrical lens is a vertical plano-concave cylindrical lens, and the focal length is-200 mm to-5 mm; the digital camera is an area-array camera, the pixel range is 1M to 16M, the recording scattering angle range is 6 degrees to 20 degrees, the angular resolution is not less than 0.002 degrees, and the exposure time is 1 mus-1000 ms adjustable.
7. The apparatus of claim 6, wherein the rainbow signal processing system comprises a computer and a synchronous controller; the computer is connected with the laser and the digital camera through the synchronous controller and synchronously controls the laser and the digital camera, including controlling the on-off and the intensity of the laser and the on-off and the exposure time of the digital camera; when the laser is a pulse laser, the frequency of the pulse light and the frequency of the digital camera are also synchronously controlled; and processing the two-dimensional rainbow image to obtain the position, the particle size and the refractive index of the atomized liquid drop in the plane to be detected.
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| CN114322826A (en) * | 2021-12-09 | 2022-04-12 | 中国科学院西安光学精密机械研究所 | Structural surface dynamic three-dimensional shape measuring device based on TOF (time of flight) in aerodynamic thermal environment |
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| CN114322826A (en) * | 2021-12-09 | 2022-04-12 | 中国科学院西安光学精密机械研究所 | Structural surface dynamic three-dimensional shape measuring device based on TOF (time of flight) in aerodynamic thermal environment |
| CN114322826B (en) * | 2021-12-09 | 2023-01-06 | 中国科学院西安光学精密机械研究所 | Structural surface dynamic three-dimensional shape measuring device based on TOF (time of flight) in aerodynamic thermal environment |
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