A high spatiotemporal dynamic range measurement system for scalar mixing processes in turbulent flows

Abstract

The present invention discloses a high spatiotemporal dynamic range measurement system for a scalar mixing process in a turbulent flow, comprising a laser emitting unit, an interaction unit, a gating unit, an imaging unit, a synchronization unit and an acquisition and processing unit. The laser emitting unit emits a high-energy laser beam; the laser sheet shaping component in the interaction unit shapes the laser beam into a laser sheet to excite the fluorescence of tracer molecules in a specified target area in the target flow; the gating unit is used to gate the fluorescence directed to the imaging unit, and a nonlinear optical crystal is used in conjunction with a polarizer and an analyzer to achieve a precise short-gate wide-high spatial resolution gating effect; the fluorescence gated by the gating is imaged by the imaging unit to obtain a tracer molecule fluorescence image; the laser emitting unit, the gating unit and the imaging unit are controlled by a synchronization signal output by the synchronization unit to achieve collaborative work; the tracer molecule fluorescence image is transmitted to the acquisition and processing unit, and after image processing, a high spatiotemporal resolution result of the scalar field mixing process in the flow is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of energy and power and planar laser-induced fluorescence imaging measurement technology, and relates to a high spatiotemporal dynamic range measurement system for a scalar mixing process in turbulence, and specifically to a laser-induced fluorescence imaging measurement system that uses a polarization-modulated crystal to achieve image gating with a high spatiotemporal dynamic range. Background Art

[0002] As society places increasingly higher demands on the combustion efficiency and pollutant emissions of combustion devices, including boilers, internal combustion engines, gas turbines, and rocket engines, the study of the mixing mechanism of fuel-oxidant in turbulent flow has become an important direction of energy and power research; at the same time, in the chemical industry, the mixing process and mixing efficiency between different reactants in turbulent flow are also core issues in chemical process and reactor design. Research in the above fields requires simultaneous understanding of the mixing process of scalar fields at large and small turbulent scales. In the existing technology, in order to simultaneously understand the influence of large-scale and small-scale turbulence on the scalar mixing process, the commonly used methods include numerical simulation, experimental measurement, scale analysis, multi-physical process coupling simulation, etc. These methods each have their own advantages and disadvantages. Among them, Planar Laser Induced Fluorescence Imaging (PLIF) is a key method for the mixing of scalar fields. Laser-Induced Fluorescence (PLIF) is an experimental measurement method commonly used to measure scalar mixing processes in turbulent flows. Its advantages mainly lie in its high spatial resolution (PLIF technology can provide a spatial resolution of up to 10 μm, so it can capture smaller-scale vortex structures and mixing processes), high temporal resolution (PLIF technology can achieve a temporal resolution of microseconds, so it can be used to measure rapidly changing turbulent fields), non-invasiveness (PLIF technology is a non-invasive technology, so it can be measured without affecting the turbulent field), and the ability to measure multiple species (PLIF technology can measure the mixing process of multiple species, so it can be used to study the mixing process of multi-component fluids). However, PLIF technology also has its own shortcomings in actual use, mainly in the detection of fluorescent substances. The requirements for quality are high (PLIF technology requires adding fluorescent substances to the fluid, requiring that the fluorescent substances have no effect on the physical properties of the fluid, and the concentration of the fluorescent substances cannot be too high, otherwise it will affect the properties of the fluid), high requirements for lighting conditions (PLIF technology needs to provide a stable light source and optical system, requiring uniform and stable lighting conditions to avoid light source drift and noise interference), and difficult signal processing (PLIF technology's signal processing is relatively difficult, requiring complex image processing and data analysis, and therefore requires high-level technical support), etc. Especially for lighting conditions, if there is a large amount of background noise interference in the measurement environment, it will greatly affect the measurement accuracy of the PLIF measurement technology, resulting in the existing turbulent scalar field mixing process measurement system being unable to achieve high temporal and spatial dynamic range measurement, and therefore unable to simultaneously understand the impact of large-scale and small-scale turbulence on the scalar mixing process. Summary of the Invention

[0003] (1) Purpose of the invention

[0004] To address the shortcomings of existing turbulent scalar field mixing process measurement systems, such as their susceptibility to background noise interference from the measurement environment and their inability to achieve high temporal and spatial dynamic range measurements, resulting in an inability to simultaneously understand the effects of large-scale and small-scale turbulence on the scalar mixing process, the present invention proposes a high temporal and spatial dynamic range measurement system for scalar mixing processes in turbulent flows. The system is a planar laser-induced fluorescence imaging measurement system that uses polarization modulation to achieve gating. A gating unit is provided in front of the incident light path of the imaging unit. The gating unit uses a nonlinear optical crystal in conjunction with a polarizer and an analyzer to achieve a precise short-gate, wide-width, and high-spatial-resolution gating effect. The gating unit is used to gate the fluorescence directed to the imaging unit. The gated fluorescence is imaged by the imaging unit to obtain a tracer molecule fluorescence image. After image processing, high temporal and spatial resolution results of the scalar field mixing process in the flow are obtained. The system can be widely used to measure fuel mixing, cold gas mixing, and temperature distribution in combustion processes; monitor reactant mixing in chemical reactions; and provide basic data for research in combustion, fluid mechanics, aerodynamics, combustion technology, and chemical technology.

[0005] (2) Technical solution

[0006] The present invention achieves its invention object and solves its technical problem by adopting the following technical solutions:

[0007] A high temporal and spatial resolution measurement system for a scalar mixing process in turbulent flow comprises at least a laser emission unit, an interaction unit, a gating unit, an imaging unit, a synchronization unit and an image processing unit, and is characterized in that:

[0008] The laser emitting unit is used to emit an ultraviolet laser beam;

[0009] The interaction unit comprises at least a laser sheet shaping component disposed on an outgoing optical path of the laser emitting unit and a target turbulent mixing field disposed downstream of the outgoing optical path of the laser sheet shaping component, wherein the laser sheet shaping component is configured to shape an incident laser beam into a laser sheet, and the laser sheet is projected onto the target turbulent mixing field to excite a molecular tracer in the target turbulent mixing field and generate tracer fluorescence;

[0010] The gate control unit includes at least an imaging lens, a polarizer, an analyzer, a polarization modulation crystal, a polarization modulation crystal high-voltage driving power supply, and a relay coupling lens, wherein the imaging lens is used to collect fluorescence to be measured, the polarizer and the analyzer are a pair of polarizers with polarization directions perpendicular to each other, the polarization modulation crystal high-voltage driving power supply is electrically connected to the polarization modulation crystal and is communicatively connected to the synchronization unit, the combination of the polarizer, the polarization modulation crystal, and the analyzer is used for gated selection, the polarization modulation crystal high-voltage driving power supply is used to modulate the polarization direction of the polarization modulation crystal under the control of an external trigger control signal, and the relay coupling lens is used to couple the fluorescence to be measured that passes through the analyzer to the imaging unit located downstream in its optical path;

[0011] The imaging unit is a CCD or CMOS camera with high spatial resolution, an input end of which is communicatively connected to the synchronization unit, and the camera exposure start time is controlled by an external trigger signal;

[0012] The synchronization unit is a multi-channel delay generator, the output end of which is communicatively connected to at least the input ends of the laser emitting unit, the gate control unit, and the imaging unit to output multiple external trigger control signals for controlling the laser emitting unit, the gate control unit, and the imaging unit one by one and synchronously;

[0013] The image processing unit has an input end that is communicatively connected to at least the output end of the imaging unit. The imaging unit transmits the received fluorescence image to the image processing unit. After processing the image, the image processing unit obtains at least the volume fraction parameter and the scalar dissipation rate parameter in the turbulent mixing process.

[0014] Preferably, the laser emitting unit is a Nd:YAG laser, and the laser of the desired wavelength is obtained by inserting an etalon into the resonant cavity of the Nd:YAG laser, or by injecting wavelength-tunable seed light into an Nd:YAG crystal for amplification.

[0015] Preferably, the laser emitting unit outputs a laser beam with a wavelength close to a quadruple frequency wavelength of 266 nm.

[0016] Preferably, the laser emitting unit is an excimer laser with finely tunable wavelength, a dye laser, a slab Nd:YVO4 laser that is convenient for achieving high pulse repetition frequency, or a slab Nd:YLF laser that is convenient for achieving high pulse repetition frequency.

[0017] Preferably, the output light spot of the laser emitting unit is a flat-top light spot, and the output light beam is a high-contrast polarized light beam.

[0018] Preferably, the single pulse energy output by the laser emitting unit is 0.01 to 600 mJ, the pulse width is 5 to 10 ns, and the repetition rate is 5 to 1e+6 Hz.

[0019] Preferably, a fluorescent tracer mixing device is provided on the air supply pipeline of the target turbulent mixing field.

[0020] When the high spatiotemporal resolution measurement system for the scalar mixing process in turbulence of the present invention is in use, if the Rayleigh scattering cross-sectional areas of the two mixing media in the target turbulent mixing field differ greatly, then there is no need to add fluorescent tracer molecules to the mixing medium. The volume fraction of a certain medium in the mixing field can be measured by measuring the Rayleigh scattering distribution in the target mixing field.

[0021] Preferably, the laser sheet shaping component includes a plurality of cylindrical concave lenses, a plurality of spherical convex lenses and a plurality of cylindrical convex lenses, wherein the plurality of cylindrical concave lenses are used to widen the light spot, the plurality of spherical convex lenses are used to shape the widened light spot into a parallel light spot, and the plurality of cylindrical convex lenses are used to adjust the thickness of the laser sheet; or, the laser sheet shaping component includes one or more microlens arrays for homogenizing the laser spot.

[0022] When using the high spatiotemporal resolution measurement system for scalar mixing in turbulence of the present invention, the thickness and height of the laser sheet should be carefully adjusted by the laser sheet shaping component to avoid excessive local laser power density leading to photodissociation in the target turbulent mixing field.

[0023] When the high spatiotemporal resolution measurement system for the scalar mixing process in turbulence of the present invention is in use, since the polarization directions of the polarizer and the analyzer are perpendicular, when the polarization modulation crystal is not working, the fluorescence collected by the imaging lens cannot pass through the gating unit. When the polarization modulation crystal is working, the fluorescence passing through the polarizer is rotated 90 degrees in the polarization direction under the action of the polarization modulation crystal, which is the same as that of the analyzer. At this time, the analyzer allows the modulated light to pass through.

[0024] Preferably, in the gate control unit, the polarizer and the analyzer use achromatic polarizers, the polarization direction of the polarizer is perpendicular to the polarization direction of the outgoing light beam of the laser emitting unit, and the imaging lens uses an image-space telecentric lens to improve the parallelism of the light entering the polarization adjustment crystal, thereby increasing the contrast during modulation. The polarization adjustment crystal uses a BBO crystal, KTP crystal, LiNbO3 crystal or LBO crystal with a smaller capacitance. The rising edge and falling edge of the high-voltage driving power supply of the polarization adjustment crystal are both less than 10ns. The number of line pairs per millimeter corresponding to the transfer resolution of the relay coupling lens is higher than the theoretical resolution of the imaging unit sensor, and the relay coupling lens has a large clear aperture.

[0025] Preferably, in the gate control unit, a narrow-band filter is installed in front of the imaging lens to filter out all stray light except the fluorescence to be measured.

[0026] Preferably, in the imaging unit, the CCD or CMOS camera is a back-illuminated sensor or a high-speed camera with a sensor cooling function.

[0027] The high-temporal-spatial-resolution measurement system for the scalar mixing process in turbulent flow of the present invention uses a gating unit to gate the fluorescence directed to an imaging unit, and the gating unit uses a nonlinear optical crystal in conjunction with a polarizer and an analyzer to achieve a precise short-gate wide-high spatial-resolution gating effect; the fluorescence selected by the gate is imaged by the imaging unit to obtain a fluorescence image of the tracer molecules in the flow mixing process; the laser emitting unit, the gating unit and the imaging unit are controlled by a synchronization signal output by the synchronization unit to achieve coordinated operation; the fluorescence image of the tracer molecules is transmitted to the acquisition and processing unit, and after image processing, a high-temporal-spatial-resolution result of the scalar field mixing process in the flow is obtained.

[0028] (3) Technical effects

[0029] Compared with the prior art, the high temporal and spatial resolution measurement system for scalar mixing in turbulent flow of the present invention has the following beneficial effects:

[0030] (1) The high spatiotemporal resolution measurement system for the scalar mixing process in turbulent flow of the present invention uses a gating unit to gate the fluorescence directed to the imaging unit. The gating unit uses a nonlinear optical crystal in conjunction with a polarizer and an analyzer to achieve a precise short-gate wide-high spatial resolution gating effect. The fluorescence selected by the gating is imaged by the imaging unit to obtain a fluorescence image of the tracer molecules during the flow mixing process. The use of microchannel plate-type gating devices is avoided, and while achieving the same gating effect, the degradation of spatial resolution caused by the microchannel plate is avoided.

[0031] (2) The high spatiotemporal resolution measurement system for the scalar mixing process in turbulent flow of the present invention avoids the photocathode light leakage problem of microchannel plate-type gating devices when gating ultraviolet incident light, thereby increasing the gating contrast under ultraviolet conditions;

[0032] (3) The high-temporal-spatial-resolution measurement system for scalar mixing processes in turbulent flows improves the temporal-spatial-resolution measurement capabilities of existing laser diagnostic technologies, providing a powerful foundation for research in combustion science, fluid mechanics, aerodynamics, combustion technology, and chemical engineering. The present invention can be widely applied to measuring fuel mixing during combustion, measuring cold gas mixing and temperature distribution during combustion, and monitoring the mixing of reactants within reactors during chemical processes, providing fundamental data for research in combustion science, fluid mechanics, aerodynamics, combustion technology, and chemical engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the high time and space resolution measurement system of the scalar mixing process in turbulent flow of the present invention.

[0034] Figure 2 It is a schematic diagram of the gate control unit in the present invention.

[0035] In the figure, there are laser emitting unit 1, laser sheet shaping component 2, target turbulent mixing field 3, gating unit 4, imaging unit 5, image processing unit 6, synchronization unit 7, retaining ring 4-1, polarization modulation crystal electrode 4-2, direction fastening screw 4-3, coupling lens mounting sleeve 4-4, analyzer 4-5, polarization modulation crystal 4-6, imaging lens mounting sleeve 4-7, and polarizer 4-8. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the implementation of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below in conjunction with the drawings in the embodiments of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be understood as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The structure and technical solutions of the present invention are further described in detail below in conjunction with the drawings, and an embodiment of the present invention is given. Specific implementation method one:

[0038] like Figure 1 As shown, the high spatiotemporal resolution measurement system for the scalar mixing process in turbulent flow of the present invention comprises at least a laser emitting unit 1, an interaction unit, a gating unit 4, an imaging unit 5, a synchronization unit 7, and an image processing unit 6. The laser emitting unit 1 is used to emit a laser beam having a wavelength that can excite the fluorescence of tracer molecules in the mixing field; the interaction unit comprises at least a laser sheet shaping component 2 disposed on the outgoing optical path of the laser emitting unit 1 and a target turbulent mixing field 3 disposed downstream of the outgoing optical path of the laser sheet shaping component 2. The laser sheet shaping component 2 is used to shape the incident laser beam into a laser sheet, which is projected onto the target turbulent mixing field 3 and excites the tracer molecules in the flame of the target turbulent mixing field 3, thereby generating molecular tracer fluorescence; the gating unit 4 comprises at least an imaging lens, a coupling lens, and Figure 2The polarizer 4-8, analyzer 4-5 and polarization modulation crystal 4-6 shown in the figure are used to collect and select the fluorescence; the imaging unit 5 includes at least one CCD or CMOS camera, which can be sensitive to the above fluorescence; the image processing unit 6 includes at least one computer with data acquisition and image processing functions, which is used to collect, store, record and process the optical signals recorded by the imaging unit 5; the synchronization unit 7 is used to output multiple trigger signals, which are respectively supplied to the laser emitting unit 1, the gating unit 4 and the imaging unit 5.

[0039] More specifically, Figure 2 As shown, the gating unit 4 of the present invention includes at least an imaging lens (installed in an imaging lens mounting sleeve 4-7), a polarizer 4-8, a polarizer 4-5, a polarization modulation crystal 4-6, a polarization modulation crystal high-voltage driving power supply (not shown in the figure), and a relay coupling lens (installed in a coupling lens mounting sleeve 4-4). The polarization modulation crystal 4-6 is electrically connected to the polarization modulation crystal high-voltage driving power supply through the polarization modulation crystal electrode 4-2, and the main components are connected by fasteners such as a retaining ring 4-1 and a direction tightening screw 4-3. In the gating unit 4, the imaging lens is used to collect the fluorescence to be measured, the polarizer 4-8 and the analyzer 4-5 are a pair of polarizers with polarization directions perpendicular to each other, the polarization modulation crystal high-voltage drive power supply is electrically connected to the polarization modulation crystal 4-6 and is communicatively connected to the synchronization unit 7, the combination formed by the polarizer 4-8, the polarization modulation crystal 4-6 and the analyzer 4-5 is used for gating, the polarization modulation crystal high-voltage drive power supply is used to modulate the polarization direction of the polarization modulation crystal 4-6 under the control of an external trigger control signal, and the relay coupling lens is used to couple the fluorescence to be measured passing through the analyzer 4-5 to the imaging unit 5 located downstream in its optical path.

[0040] In a preferred embodiment of the present invention, for the gating unit 4, since the polarization directions of the polarizer 4-8 and the analyzer 4-5 are perpendicular, when the polarization modulation crystal 4-6 is not working, the fluorescence collected by the imaging lens cannot pass through the gating unit 4. When the polarization modulation crystal 4-6 is working, the fluorescence passing through the polarizer 4-8 is rotated 90 degrees in the polarization direction under the action of the polarization modulation crystal 4-6, which is the same as that of the analyzer 4-5. At this time, the analyzer 4-5 allows the modulated light to pass through.

[0041] In a preferred embodiment of the present invention, the laser emitting unit 1 is preferably a Nd:YAG pulsed laser with a quadrupled wavelength of 266 nm. The laser emitting unit preferably outputs a single pulse energy of 0.01 to 600 mJ, a pulse width of 5 to 10 ns, and a repetition rate of 5 to 1e+6 Hz. The laser emitting unit outputs a flat-top spot, and the output beam is a high-contrast polarized beam.

[0042] In a preferred embodiment of the present invention, the laser emitting unit 1 , the gate control unit 4 and the imaging unit 5 operate synchronously under the trigger signal of the synchronization unit 7 .

[0043] In a preferred embodiment of the present invention, the laser sheet shaping component 2 includes multiple cylindrical concave lenses, multiple spherical convex lenses, and multiple cylindrical convex lenses. The multiple cylindrical concave lenses are used to widen the light spot, the multiple spherical convex lenses are used to shape the widened light spot into a parallel light spot, and the multiple cylindrical convex lenses are used to adjust the thickness of the laser sheet. Alternatively, the laser sheet shaping component includes one or more microlens arrays for homogenizing the laser spot. When using the high-temporal-spatial-resolution measurement system for scalar mixing in turbulent flow, the laser sheet thickness and height should be carefully adjusted using the laser sheet shaping component 2 to avoid excessive local laser power density, which can lead to photodissociation in the target turbulent mixing field.

[0044] The high-temporal-spatial-resolution measurement system for the scalar mixing process in turbulent flow of the present invention uses a gating unit to gate the fluorescence directed to an imaging unit, and the gating unit uses a nonlinear optical crystal in conjunction with a polarizer and an analyzer to achieve a precise short-gate wide-high spatial-resolution gating effect; the fluorescence selected by the gate is imaged by the imaging unit to obtain a fluorescence image of the tracer molecules in the flow mixing process; the laser emitting unit, the gating unit and the imaging unit are controlled by a synchronization signal output by the synchronization unit to achieve coordinated operation; the fluorescence image of the tracer molecules is transmitted to the acquisition and processing unit, and after image processing, a high-temporal-spatial-resolution result of the scalar field mixing process in the flow is obtained. Specific implementation method two:

[0046] The difference between this embodiment and the specific embodiment one is that the laser emitting unit 1 is an ultraviolet continuous laser, and the laser emitting unit 1 works independently and no longer works synchronously with the gating unit 4 and the imaging unit 5; at the same time, the gating unit 4 and the imaging unit 5 keep working synchronously, and the other components and connection methods are the same as the specific embodiment one. Specific implementation method three:

[0048] The difference between this embodiment and the first embodiment is that the laser emitting unit 1 uses a method of injecting wavelength-tunable seed light into Nd:YAG crystal amplification to obtain the required wavelength laser, and the other components and connection methods are the same as those in the first embodiment. Specific implementation method four:

[0050] The difference between this embodiment and the first embodiment is that a narrow-band filter is included in front of the imaging lens of the gating unit 4 for spectrally gating the tracer fluorescence. The other components and connection methods are the same as those of the first embodiment. Specific implementation method five:

[0052] If the Rayleigh scattering cross-sectional areas of the two mixed media in the target mixed field differ greatly, then there is no need to add fluorescent tracer molecules to the mixed medium. The volume fraction of a certain medium in the mixed field can be measured by measuring the Rayleigh scattering distribution in the target mixed field. The other compositions and connection methods are the same as those in the first specific implementation method.

[0053] The above embodiments fully and effectively achieve the objectives of the present invention. Those skilled in the art will appreciate that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the above specific embodiments. Although the present invention has been described with reference to the embodiments currently considered to be the most practical and preferred, it should be understood that the present invention is not limited to the disclosed embodiments, and any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A high temporal and spatial resolution measurement system for scalar mixing in turbulent flow, comprising at least a laser emission unit, an interaction unit, a gating unit, an imaging unit, a synchronization unit, and an image processing unit, characterized in that: The laser emitting unit is used to emit an ultraviolet laser beam, the output laser wavelength is a laser beam of about 266 nm of the quadruple frequency wavelength, and the output single pulse energy is 0.01-600 mJ, the pulse width is 5-10 ns, and the repetition rate is 5-1e+6 Hz; The interaction unit comprises at least a laser sheet shaping component disposed on an outgoing optical path of the laser emitting unit and a target turbulent mixing field disposed downstream of the outgoing optical path of the laser sheet shaping component, wherein the laser sheet shaping component is configured to shape an incident laser beam into a laser sheet, and the laser sheet is projected onto the target turbulent mixing field to excite a molecular tracer in the target turbulent mixing field and generate tracer fluorescence; The gate control unit includes at least an imaging lens, a polarizer, an analyzer, a polarization modulation crystal, a polarization modulation crystal high-voltage driving power supply, and a relay coupling lens, wherein the imaging lens is used to collect the fluorescence to be measured, the polarizer and the analyzer are a pair of polarizers with polarization directions perpendicular to each other, the polarization modulation crystal high-voltage driving power supply is electrically connected to the polarization modulation crystal and is communicatively connected to the synchronization unit, the combination formed by the polarizer, the polarization modulation crystal and the analyzer is used for gated selection, the polarization modulation crystal high-voltage driving power supply is used to modulate the polarization direction of the polarization modulation crystal under the control of an external trigger control signal, and the relay coupling lens is used to couple the fluorescence to be measured that passes through the analyzer to the imaging unit located downstream of its optical path, and wherein, The polarizer and analyzer use achromatic polarizers, the polarization direction of the polarizer is perpendicular to the polarization direction of the output light beam of the laser emitting unit, the polarization modulation crystal uses a BBO crystal, KTP crystal, LiNbO3 crystal or LBO crystal with a relatively small capacitance, the rising edge and falling edge of the high-voltage driving power supply of the polarization modulation crystal are both less than 10 ns, the number of line pairs per millimeter corresponding to the transmission resolution of the relay coupling lens is higher than the theoretical resolution of the imaging unit sensor, and the relay coupling lens has a large clear aperture; The imaging unit is a CCD or CMOS camera with high spatial resolution, an input end of which is communicatively connected to the synchronization unit, and the camera exposure start time is controlled by an external trigger signal; The synchronization unit is a multi-channel delay generator, the output end of which is communicatively connected to at least the input ends of the laser emitting unit, the gate control unit, and the imaging unit to output multiple external trigger control signals for controlling the laser emitting unit, the gate control unit, and the imaging unit one by one and synchronously; The image processing unit has an input end that is communicatively connected to at least the output end of the imaging unit. The imaging unit transmits the received fluorescence image to the image processing unit. After processing the image, the image processing unit obtains at least the volume fraction parameter and the scalar dissipation rate parameter in the turbulent mixing process.

2. The high temporal and spatial resolution measurement system for scalar mixing process in turbulent flow according to claim 1, characterized in that: The laser emitting unit is a Nd:YAG laser, which obtains laser light of desired wavelength by inserting an etalon into the resonant cavity of the Nd:YAG laser, or by injecting wavelength-tunable seed light into the Nd:YAG crystal for amplification.

3. The high temporal and spatial resolution measurement system for scalar mixing process in turbulent flow according to claim 1, characterized in that: The laser emitting unit is an excimer laser with finely tunable wavelength, a dye laser, a slab Nd:YVO4 laser that is convenient for achieving high pulse repetition frequency, or a slab Nd:YLF laser that is convenient for achieving high pulse repetition frequency.

4. The high temporal and spatial resolution measurement system for scalar mixing process in turbulent flow according to claim 1, characterized in that: The output light spot of the laser emitting unit is a flat-top light spot, and the output light beam is a high-contrast polarized light beam.

5. The high temporal and spatial resolution measurement system for scalar mixing process in turbulent flow according to claim 1, characterized in that: A fluorescent tracer mixing device is provided on the air supply pipeline of the target turbulent mixing field.

6. The high temporal and spatial resolution measurement system for scalar mixing process in turbulent flow according to claim 1, characterized in that: The laser sheet shaping component includes multiple cylindrical concave lenses, multiple spherical convex lenses and multiple cylindrical convex lenses, wherein the multiple cylindrical concave lenses are used to widen the light spot, the multiple spherical convex lenses are used to shape the widened light spot into a parallel light spot, and the multiple cylindrical convex lenses are used to adjust the thickness of the laser sheet; or, the laser sheet shaping component includes one or more microlens arrays for homogenizing the laser spot.

7. The high temporal and spatial resolution measurement system for scalar mixing process in turbulent flow according to claim 1, characterized in that: In the gate control unit, a narrow-band filter is installed in front of the imaging lens to filter out all stray light except the fluorescence to be measured.

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