System and method for measuring dynamic atomization mixing ratio distribution

Abstract

The invention provides a system and a method for measuring distribution of a dynamic atomization mixing ratio, which can solve the problems that the existing measuring method is not suitable for measuring the dynamic atomization mixing ratio under high characteristic frequency and the measuring error is large due to overlapping of wave bands of two adopted fluorescent dyes. The method comprises the following steps: selecting a fluorescence wavelength range, wherein the step is used for distinguishing and simultaneously shooting the fluorescence of an oxidant simulation liquid and the fluorescence of a fuel simulation liquid; correcting the projection position of the sheet light, wherein the step is used for correcting the position information of the laser sheet light; correcting an optimal background noise gray threshold, wherein the step is used for improving the linearity of the relationship between the fluorescence intensity and the flow intensity; shooting a dynamic atomization fluorescence image of the injector, wherein the step is used for obtaining an oxidant simulation liquid atomization fluorescence image and a fuel simulation liquid atomization fluorescence image which are synchronous in time and space; and calculating the atomization mixing ratio based on the fluorescence image, wherein the step is used for obtaining the spatial and temporal distribution of the dynamic atomization mixing ratio through projection calculation.

Description

Technical Field

[0001] The invention relates to how to measure the atomization mixing ratio distribution of an engine injector, and in particular to a system and method for measuring the dynamic atomization mixing ratio distribution. Background Art

[0002] Liquid propellant atomization is the prerequisite for the combustion of liquid rocket engines. Liquid propellants include fuel and oxidizer. During the atomization process, the atomization mixing ratio of oxidizer and fuel has a great influence on the combustion process. The pressure oscillation in the combustion chamber will affect the atomization process of the liquid propellant, forming a dynamic atomization, which in turn will couple with the combustion process under certain conditions, triggering unstable combustion of the liquid power system or increasing the pressure amplitude of the combustion chamber. Therefore, studying the atomization mixing characteristics of the injector under pressure disturbance conditions is of great significance to improving the specific impulse performance and reliability of the engine.

[0003] Since the measurement object is the cold spray field of the engine injector, the contact measurement method will cause serious interference to the measurement object, so the non-contact measurement method is usually used for measurement. The existing non-contact measurement method is mainly the laser induced fluorescence method, that is, adding two different fluorescent dyes to the oxidant and the fuel, taking the fluorescence image by high-speed photography, and calculating the atomization mixing ratio according to the light intensity of the fluorescence image. However, the existing laser induced fluorescence method is not suitable for the measurement of dynamic atomization mixing ratio at high characteristic frequency, and in the measurement process, the fluorescence bands of the rhodamine 610 and rhodamine 590 fluorescent dyes used overlap, resulting in large measurement errors. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problems that the existing laser induced fluorescence method is not suitable for measuring the dynamic atomization mixing ratio at a high characteristic frequency and that the fluorescence bands of the used rhodamine 610 and rhodamine 590 fluorescent dyes overlap, resulting in large measurement errors, and to provide a system and method for measuring the dynamic atomization mixing ratio distribution.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A system for measuring dynamic atomization mixing ratio distribution, which is special in that it includes a laser sheet light generating unit, an injector unit, a spectrometer, a trigger delay pulse signal generator, a clock delay pulse signal generator, a high-speed data acquisition instrument, a disturbance device, a continuous laser, software, a first optical observation device and a second optical observation device;

[0007] The laser sheet light generating unit is used to emit laser light and form laser sheet light;

[0008] The injector unit is used to inject an oxidant simulation liquid containing a first fluorescent dye and a fuel simulation liquid containing a second fluorescent dye into the atomization cross-sectional area to be measured; the fluorescence wavelength distributions of the first fluorescent dye and the second fluorescent dye do not overlap;

[0009] The spectrometer is used to measure the fluorescence wavelength distribution and intensity of the first fluorescent dye and the second fluorescent dye;

[0010] The trigger delay pulse signal generator is electrically connected to the high-speed data acquisition instrument, the first optical observation device, and the second optical observation device, respectively, and is used to send a TTL trigger signal to the high-speed data acquisition instrument, the first optical observation device, and the second optical observation device;

[0011] The clock delay pulse signal generator is electrically connected to the laser sheet light generating unit, the high-speed data acquisition instrument, the first optical observation device, and the second optical observation device, respectively, and is used to send an external clock signal to the laser sheet light generating unit, the high-speed data acquisition instrument, the first optical observation device, and the second optical observation device;

[0012] The high-speed data acquisition instrument is also electrically connected to the laser sheet light generating unit and the injector unit, respectively, and is used to collect the laser intensity, the pre-injection pressure of the oxidant simulation liquid, and the pre-injection pressure of the fuel simulation liquid;

[0013] The disturbance device is connected to the injector unit and is used to disturb the pre-injection pressure of the oxidant simulated liquid and the fuel simulated liquid;

[0014] The continuous laser is used to calibrate the background noise of the first optical observation device and the second optical observation device respectively;

[0015] The first optical observation device and the second optical observation device are used to take fluorescent images of the atomized and mixed droplets from two different directions respectively;

[0016] The software is used to receive the fluorescent images of the atomized mixed droplets taken by the first optical observation device and the second optical observation device.

[0017] Furthermore, it also includes a calibration target plate; the calibration target plate is arranged in the atomization cross-section area to be measured, and is used for collecting calibration images; the first optical observation device and the second optical observation device are respectively used to take calibration images of the calibration target plate from two different directions; the software is used to receive the calibration images of the calibration target plate taken by the first optical observation device and the second optical observation device;

[0018] The first fluorescent dye is RH414 fluorescent dye; the second fluorescent dye is rhodamine 590 fluorescent dye;

[0019] The acquisition frequency of the high-speed data acquisition instrument is 1-2MS / s;

[0020] The trigger delay of the first optical observation device and the second optical observation device is no more than 1 μs, the filter wavelength range of the first optical observation device is 650nm-790nm, which is used to transmit the fluorescence of the wavelength of RH414 fluorescent dye, and the filter wavelength range of the second optical observation device is 550nm-570nm, which is used to transmit the fluorescence of the wavelength of rhodamine 590 fluorescent dye;

[0021] The external clock delay of the clock delay pulse signal generator is no more than 1 μs;

[0022] The disturbance frequency of the disturbance device is no more than 4000 Hz.

[0023] Furthermore, the acquisition frequency of the high-speed data acquisition instrument is 2MS / s.

[0024] Furthermore, the laser sheet light generating unit comprises a high-frequency pulse laser for emitting laser light, a photodetector mounted on the high-frequency pulse laser, and a sheet light lens assembly arranged on the laser light path; the laser frequency of the high-frequency pulse laser is 40kHz to 80kHz, and the laser wavelength is 532nm; the sheet light lens assembly is used to form the laser sheet light;

[0025] The injector unit comprises an oxidant simulated liquid supply branch, a fuel simulated liquid supply branch, an injector, an automatic timing controller and two pressure sensors; the oxidant simulated liquid supply branch and the fuel simulated liquid supply branch are connected to two inlets of the injector; the automatic timing controller is electrically connected to a first valve on the oxidant simulated liquid supply branch and a second valve on the fuel simulated liquid supply branch respectively; the two pressure sensors are connected to the injector and are used to measure the pre-injection pressure of the oxidant simulated liquid and the fuel simulated liquid respectively;

[0026] The first optical observation device comprises a first optical lens, a first filter set and a first high-speed camera arranged in sequence; the filter wavelength range of the first filter set is 650nm to 790nm; the second optical observation device comprises a second optical lens, a second filter set and a second high-speed camera arranged in sequence; the filter wavelength range of the second filter set is 550nm to 570nm;

[0027] The first high-speed camera and the second high-speed camera are electrically connected to a trigger delay pulse signal generator;

[0028] The clock delay pulse signal generator is electrically connected to the high-frequency pulse laser, the high-speed data acquisition instrument, the first high-speed camera, and the second high-speed camera respectively;

[0029] The high-speed data acquisition instrument is also electrically connected to the photoelectric detector and the two pressure sensors respectively;

[0030] The disturbance device is connected to the oxidant simulation liquid supply branch and the fuel simulation liquid supply branch;

[0031] The continuous laser is used to calibrate the background noise of the first high-speed photography and the second high-speed photography respectively;

[0032] The software is used to receive the fluorescent images of the atomized and mixed droplets taken by the first high-speed camera and the second high-speed camera.

[0033] At the same time, the present invention also provides a method for measuring dynamic atomization mixing ratio distribution, using the above-mentioned system for measuring dynamic atomization mixing ratio distribution, characterized in that it includes the following steps:

[0034] 1) Selection of a fluorescence wavelength range; the fluorescence wavelength range is selected to achieve the distinction and simultaneous shooting of the fluorescence of the oxidant simulation liquid and the fluorescence of the fuel simulation liquid;

[0035] 2) Correction of the projection position of the light sheet; the correction of the projection position of the light sheet is used to correct the position information of the laser light sheet;

[0036] 3) Optimal background noise grayscale threshold correction; the optimal background noise grayscale threshold correction is used to improve the linearity of the relationship between fluorescence intensity and flow intensity;

[0037] 4) Shooting of dynamic atomization fluorescence images of the injector; the dynamic atomization fluorescence images of the injector are used to obtain spatiotemporally synchronized fluorescence images of the atomization of the oxidant simulation liquid and the atomization fluorescence images of the fuel simulation liquid;

[0038] 5) Calculation of atomization mixing ratio based on fluorescence images; the calculation of atomization mixing ratio based on fluorescence images is used to obtain the spatiotemporal distribution of the dynamic atomization mixing ratio through projection calculation.

[0039] Furthermore, the step of selecting the fluorescence wavelength range is specifically as follows:

[0040] 1.1) The laser beam emitted by the high-frequency pulse laser passes through the light sheet lens assembly to form a laser sheet light;

[0041] 1.2) The laser sheet light irradiates the oxidant simulated liquid to generate a corresponding first fluorescence, and the laser sheet light irradiates the fuel simulated liquid to generate a corresponding second fluorescence, and the wavelength distribution of the first fluorescence and the second fluorescence are measured by a spectrometer respectively;

[0042] 1.3) Determine the wavelengths of the first filter set and the second filter set according to the measured wavelength distributions of the first fluorescence and the second fluorescence.

[0043] Furthermore, the step of correcting the projection position of the light sheet is specifically as follows:

[0044] 2.1) Place the calibration target plate in the atomization cross-section area to be measured, determine the zero point and X, Y, and Z directions of the physical coordinate system, use the first high-speed photography and the second high-speed photography to obtain the calibration images of the calibration target plate respectively, and calculate the oxidant fluorescence image projection fitting relationship function X between the image coordinate system and the physical coordinate system of the calibration images in different directions O_img =f O (X, Y, Z) and the fuel fluorescence image projection fitting function X F_img =f F (X, Y, Z), and then derive the aberration formula of the Z-direction projection image based on the fitting relationship function:

[0045]

[0046] Among them, X F_img and X O_img Calibrate the coordinates of the image in the image coordinate system in two directions, dX F -dX o is the image difference between the projected images in two directions, dZ is the distance between the real physical plane and the projection plane, f O The partial derivative of (X,Y,Z) in the Z direction, f F The partial derivative of (X,Y,Z) in the Z direction, f O The partial derivative of (X,Y,Z) in the X direction, f F The partial derivative of (X,Y,Z) in the X direction;

[0047] 2.2) Adjust the laser sheet light to a plane position that overlaps with the calibration target as much as possible, and control the distance between the laser sheet light and the Z=0 plane of the calibration target within 2 mm. Then remove the calibration target and take a fluorescent image of the atomized droplets.

[0048] 2.3) According to the fluorescence image of the atomized droplet, according to the fitting relationship function of step 2.1), get Perform the k-th projection image calculation in two directions, where dZ0=0;

[0049] 2.4) Use the cross-correlation algorithm to calculate the difference dX between the projection images in two directions F -dX o If the aberration is greater than 0.2 mm, change the aberration dX F -dX o Substitute the data into the aberration formula derived in step 2.1) to calculate the k-th Z-direction position information correction value dZ k , Return to 2.3) and perform k+1 times of sheet light position correction calculation. If the aberration is less than 0.2 mm, it means The sheet light position correction is in place and the sheet light position correction data is saved As the Z-direction position information for subsequent fluorescence image projection.

[0050] Furthermore, the steps of correcting the optimal background noise grayscale threshold are specifically as follows:

[0051] 3.1) Using different exposure times for the first high-speed photography and the second high-speed photography, respectively, to photograph the light spot formed by the laser irradiation emitted by the continuous laser;

[0052] 3.2) Perform linear regression on the spot intensity and exposure time to obtain the optimal background noise grayscale threshold.

[0053] Furthermore, the steps of shooting the dynamic atomization fluorescence image of the injector are specifically as follows:

[0054] 4.1) Installing the first filter set and the second filter set determined in step 1.3) between the first high-speed camera and the first optical lens, and between the second high-speed camera and the second optical lens;

[0055] 4.2) setting the grayscale threshold of the first high-speed photography and the second high-speed photography to the optimal background noise grayscale threshold determined in step 3.2);

[0056] 4.3) The automatic timing controller opens the first valve and the second valve at the same time, and the oxidant simulated liquid and the fuel simulated liquid are sprayed out through the injector and atomized and mixed to form an atomization area, and the disturbance device is started to apply disturbances of different frequencies to the oxidant simulated liquid supply pipeline and the fuel simulated liquid supply pipeline at the same time;

[0057] 4.4) A high-frequency pulse laser emits a laser beam, which passes through a light-sheet lens assembly to form a laser sheet light; the laser sheet light irradiates the atomized area and excites it to produce fluorescence;

[0058] 4.5) The first high-speed photography and the second high-speed photography take fluorescent images of the atomized area from two directions respectively.

[0059] Furthermore, the step of calculating the atomization mixing ratio based on the fluorescence image is specifically as follows:

[0060] 5.1) Correcting the intensity of the fluorescence images in two directions taken in step 4.5) according to the voltage signal obtained by the photodetector;

[0061] 5.2) According to the fitting relationship function X in step 2.1) F_img =f F (X,Y,Z) and X O_img =f O(X, Y, Z) and the light sheet position correction data saved in step 2.4) Project the fluorescence image obtained in step 4.5) into the physical coordinate system to obtain a fluorescence image of N×M pixels;

[0062] 5.3) dividing the N×M pixel fluorescence image projected in step 5.2) into multiple query windows of n×m pixels respectively;

[0063] 5.4) Calculate the fluorescence gray value integral I of the oxidant simulation solution in all query windows according to the following formula: O :

[0064]

[0065] Where i is the number of the query window in the X direction of the fluorescence image, j is the number of the query window in the Y direction of the fluorescence image, (I O ) i,j (X i ,Y j ) is the fluorescence gray value integral of the oxidant simulation liquid in the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescence image, (X i ,Y j ) is the physical coordinate of the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescent image;

[0066] 5.5) Calculate the flow intensity of the oxidant simulation liquid in each query window according to the following formula:

[0067]

[0068] Among them, A i,j is the area of ​​the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescence image, m O is the total flow rate of the oxidant simulation liquid;

[0069] 5.6) Calculate the atomization mixing ratio of each query window to complete the measurement of the dynamic atomization mixing ratio distribution; specifically, calculate the atomization mixing ratio of each query window according to the following formula:

[0070]

[0071] Among them, g F (X i , Y j ) is the fuel simulation flow intensity for each query window, and its calculation method is the same as g O (X i , Y j ) is calculated in the same way.

[0072] Beneficial effects of the present invention:

[0073] 1. The present invention provides a system and method for measuring dynamic atomization mixing ratio distribution, wherein, under the combined action of a laser sheet light generating unit and a disturbance device, non-contact high-speed dynamic measurement of the atomization mixing ratio distribution of injector propellant under 0Hz to 4000Hz pressure disturbance is achieved. The method is suitable for measuring the dynamic atomization mixing ratio under high characteristic frequency, and because the fluorescence wavelength distribution of the selected first fluorescent dye and the second fluorescent dye does not overlap and has a clear boundary, the measurement accuracy of the atomization mixing ratio can be improved.

[0074] 2. In the present invention, since the acquisition frequency of the high-speed data acquisition instrument is 1-2MS / s, the trigger delay of the first optical observation device and the second optical observation device is no more than 1μs, and the external clock delay of the clock delay pulse signal generator is no more than 1μs, the synchronization error of the system of the present invention is no more than 1μs, and the phase angle error of the sampling rate of the system is no more than 1.8°.

[0075] 3. The software in the present invention has an image self-correction function, wherein the intensity of the fluorescence image is corrected by the collected voltage signal of each pulse power representing the laser intensity; the aberration caused by the incomplete overlap of the laser irradiation plane and the calibration target disk is corrected by using the aberration to inversely calculate the distance between the laser irradiation plane and the calibration target disk to correct the spatial calibration relationship; the background noise of the experimental image is filtered by calibrating the optimal grayscale threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 is a structural schematic diagram of a system embodiment for measuring dynamic atomization mixing ratio distribution according to the present invention;

[0077] Figure 2 The fluorescence spectra of RH414 fluorescent dye and rhodamine 590 fluorescent dye in a system embodiment of the present invention for measuring dynamic atomization mixing ratio distribution;

[0078] Figure 3 is a flowchart of an embodiment of a method for measuring dynamic atomization mixing ratio distribution of the present invention;

[0079] Figure 4 Schematic diagram of an external clock signal of a clock delay pulse signal generator in an embodiment of a method for measuring dynamic atomization mixing ratio distribution of the present invention;

[0080] Figure 5 It is a schematic diagram of the aberration self-correction function in step 2) of an embodiment of a method for measuring dynamic atomization mixing ratio distribution of the present invention.

[0081] Description of reference numerals:

[0082] 1-first fluorescent dye, 2-second fluorescent dye, 3-injector, 4-high-frequency pulse laser, 5-photoelectric detector, 6-light lens assembly, 7-automatic timing controller, 8-first valve, 9-second valve, 10-pressure sensor, 11-spectrometer, 12-first filter group, 13-second filter group, 14-first optical lens, 15-second optical lens, 16-first high-speed photography, 17-second high-speed photography, 18-calibration target, 19-continuous laser, 20-trigger delay pulse signal generator, 21-clock delay pulse signal generator, 22-high-speed data acquisition instrument, 23-disturbance device, 24-software, 211-high-speed photography clock, 212-high-frequency pulse laser clock. DETAILED DESCRIPTION

[0083] like Figure 1-Figure 2 As shown, a system for measuring dynamic atomization mixing ratio distribution includes a laser sheet light generating unit, an injector unit, a calibration target plate 18, a spectrometer 11, a trigger delay pulse signal generator 20, a clock delay pulse signal generator 21, a high-speed data acquisition instrument 22, a disturbance device 23, a continuous laser 19, software 24, a first optical observation device, and a second optical observation device. Specifically, the laser sheet light generating unit includes a high-frequency pulse laser 4 for emitting laser light, a photodetector 5 mounted on the high-frequency pulse laser 4, and a sheet light lens assembly 6 arranged on the laser light path. The laser frequency of the high-frequency pulse laser 4 is 40kHz to 80kHz, and the laser wavelength is 532nm. The sheet light lens assembly 6 is used to form a laser sheet light.

[0084] The injector unit includes an oxidant simulating liquid supply branch, a fuel simulating liquid supply branch, an injector 3, an automatic timing controller 7 and two pressure sensors 10, wherein the oxidant simulating liquid supply branch and the fuel simulating liquid supply branch are connected to the two inlets of the injector 3, the injector 3 is used to spray the oxidant simulating liquid containing the first fluorescent dye 1 and the fuel simulating liquid containing the second fluorescent dye 2 to the atomization cross-sectional area to be measured, and the fluorescence wavelength distribution of the first fluorescent dye 1 and the second fluorescent dye 2 does not overlap, the automatic timing controller 7 is electrically connected to the first valve 8 on the oxidant simulating liquid supply branch and the second valve 9 on the fuel simulating liquid supply branch, and the two pressure sensors 10 are connected to the injector 3, respectively, for measuring the pre-spray pressure of the oxidant simulating liquid and the fuel simulating liquid. The calibration target plate 18 is set in the atomization cross-sectional area to be measured for the acquisition of calibration images. The spectrometer 11 is used to measure the fluorescence wavelength distribution and intensity of the first fluorescent dye 1 and the second fluorescent dye 2. In this embodiment, the first fluorescent dye 1 is RH414 fluorescent dye, and the second fluorescent dye 2 is rhodamine 590 fluorescent dye.

[0085] The first optical observation device includes a first optical lens 14, a first filter group 12 and a first high-speed camera 16 which are arranged in sequence. The second optical observation device includes a second optical lens 15, a second filter group 13 and a second high-speed camera 17 which are arranged in sequence. The first high-speed camera 16 and the second high-speed camera 17 are used to respectively take a calibration image of a calibration target plate 18 and a fluorescent image of atomized mixed droplets from two different directions. The trigger delay of the first high-speed camera 16 and the second high-speed camera 17 is not greater than 1 μs, the filtering wavelength range of the first filter group 12 is 650 nm to 790 nm, which is used to transmit the fluorescence of the wavelength of RH414 fluorescent dye, and the filtering wavelength range of the second filter group 13 is 550 nm to 570 nm, which is used to transmit the fluorescence of the wavelength of Rhodamine 590 fluorescent dye.

[0086] The trigger delay pulse signal generator 20 is electrically connected to the high-speed data acquisition instrument 22, the first high-speed camera 16, and the second high-speed camera 17, respectively, and is used to send a TTL trigger signal to the high-speed data acquisition instrument 22, the first high-speed camera 16, and the second high-speed camera 17. The clock delay pulse signal generator 21 is electrically connected to the high-frequency pulse laser 4, the high-speed data acquisition instrument 22, the first high-speed camera 16, and the second high-speed camera 17, respectively, and is used to send an external clock signal to the high-frequency pulse laser 4, the high-speed data acquisition instrument 22, the first high-speed camera 16, and the second high-speed camera 17. The external clock delay of the clock delay pulse signal generator 21 is not greater than 1μs. The high-speed data acquisition instrument 22 is also electrically connected to the photoelectric detector 5 and the two pressure sensors 10, respectively, and is used to collect laser intensity, the pre-injection pressure of the oxidant simulated liquid, and the pre-injection pressure of the fuel simulated liquid. The acquisition frequency of the high-speed data acquisition instrument 22 is 1-2MS / s. The acquisition frequency of the high-speed data acquisition instrument 22 in this embodiment is 2MS / s. The disturbance device 23 is connected to the oxidant simulated liquid supply branch and the fuel simulated liquid supply branch respectively, and is used to disturb the pre-spray pressure of the oxidant simulated liquid and the fuel simulated liquid. The disturbance frequency of the disturbance device 23 is not greater than 4000 Hz. The continuous laser 19 is used to calibrate the background noise of the first high-speed camera 16 and the second high-speed camera 17 respectively. The software 24 is used to receive the calibration images of the calibration target plate 18 taken by the first high-speed camera 16 and the second high-speed camera 17 and the fluorescent images of the droplets after atomization and mixing.

[0087] like Figure 3-Figure 5 As shown, this embodiment also provides a method for measuring dynamic atomization mixing ratio distribution, using the above-mentioned system for measuring dynamic atomization mixing ratio distribution, including the following steps:

[0088] 1) Selection of fluorescence wavelength range: The fluorescence wavelength range is selected to achieve the distinction and simultaneous shooting of the fluorescence of the oxidant simulation liquid and the fuel simulation liquid; specifically:

[0089] 1.1) The laser beam emitted by the high-frequency pulse laser 4 passes through the light sheet lens assembly 6 to form a laser sheet light;

[0090] 1.2) The laser sheet light irradiates the oxidant simulated liquid to generate a corresponding first fluorescence, and the laser sheet light irradiates the fuel simulated liquid to generate a corresponding second fluorescence, and the wavelength distribution of the first fluorescence and the second fluorescence are measured by the spectrometer 11 respectively;

[0091] 1.3) Determine the wavelengths of the first filter set 12 and the second filter set 13 according to the measured wavelength distributions of the first fluorescence and the second fluorescence.

[0092] 2) Correction of the projection position of the light sheet: Correction of the projection position of the light sheet is used to correct the position information of the laser light sheet; specifically:

[0093] 2.1) Place the calibration target plate 18 in the atomization cross-section area to be measured, determine the zero point and the X, Y, and Z directions of the physical coordinate system, use the first high-speed photography 16 and the second high-speed photography 17 to obtain calibration images of the calibration target plate 18 respectively, and calculate the oxidant fluorescence image projection fitting relationship function X between the image coordinate system and the physical coordinate system of the calibration images in different directions O_img =f O (X, Y, Z) and the fuel fluorescence image projection fitting function X F_img =f F (X, Y, Z), and then derive the aberration formula of the Z-direction projection image based on the fitting relationship function:

[0094]

[0095] Among them, X F_img and X O_img Calibrate the coordinates of the image in the image coordinate system in two directions, dX F -dX o is the image difference between the projected images in two directions, dZ is the distance between the real physical plane and the projection plane, f O The partial derivative of (X,Y,Z) in the Z direction, f F The partial derivative of (X,Y,Z) in the Z direction, f O The partial derivative of (X,Y,Z) in the X direction, f F The partial derivative of (X,Y,Z) in the X direction;

[0096] 2.2) Adjust the laser sheet light to a plane position that overlaps with the calibration target plate 18 as much as possible, and control the distance between the laser sheet light and the Z=0 plane of the calibration target plate 18 to be within 2 mm. Then remove the calibration target plate 18 and take a fluorescent image of the atomized droplets;

[0097] 2.3) According to the fluorescence image of the atomized droplet, according to the fitting relationship function of step 2.1), get Perform the k-th projection image calculation in two directions, where dZ0=0;

[0098] 2.4) Use the cross-correlation algorithm to calculate the difference dX between the projection images in two directions F -dX o If the aberration is greater than 0.2 mm, change the aberration dX F -dX o Substitute the data into the aberration formula derived in step 2.1) to calculate the k-th Z-direction position information correction value dZ k , Return to 2.3) and perform k+1 times of sheet light position correction calculation. If the aberration is less than 0.2 mm, it means The sheet light position correction is in place and the sheet light position correction data is saved As the Z-direction position information for subsequent fluorescence image projection.

[0099] 3) Optimal background noise grayscale threshold correction: The optimal background noise grayscale threshold correction is used to improve the linearity of the relationship between fluorescence intensity and flow intensity; specifically:

[0100] 3.1) Using different exposure times for the first high-speed photography 16 and the second high-speed photography 17, respectively, to photograph the light spot formed by the laser irradiation emitted by the continuous laser 19;

[0101] 3.2) Perform linear regression on the spot intensity and exposure time to obtain the optimal background noise grayscale threshold.

[0102] 4) Shooting of dynamic atomization fluorescence images of the injector; Shooting of dynamic atomization fluorescence images of the injector is used to obtain spatiotemporally synchronized fluorescence images of atomization of the oxidant simulation liquid and atomization of the fuel simulation liquid; specifically:

[0103] 4.1) Installing the first filter set 12 and the second filter set 13 determined in step 1.3) between the first high-speed camera 16 and the first optical lens 14, and between the second high-speed camera 17 and the second optical lens 15;

[0104] 4.2) setting the grayscale thresholds of the first high-speed photograph 16 and the second high-speed photograph 17 to the optimal background noise grayscale threshold determined in step 3.2);

[0105] 4.3) The automatic timing controller 7 opens the first valve 8 and the second valve 9 at the same time, the oxidant simulated liquid and the fuel simulated liquid are sprayed out through the injector 3 and then atomized and mixed to form an atomization zone, and the disturbance device 23 is started to simultaneously apply disturbances of different frequencies to the oxidant simulated liquid supply pipeline and the fuel simulated liquid supply pipeline;

[0106] 4.4) The high-frequency pulse laser 4 emits a laser beam, which passes through the light-sheet lens assembly 6 to form a laser sheet light; the laser sheet light irradiates the atomized area and excites it to produce fluorescence;

[0107] 4.5) The first high-speed camera 16 and the second high-speed camera 17 take fluorescent images of the atomized area from two directions respectively.

[0108] 5) Calculation of atomization mixing ratio based on fluorescence image: The calculation of atomization mixing ratio based on fluorescence image is used to obtain the spatiotemporal distribution of dynamic atomization mixing ratio through projection calculation; specifically:

[0109] 5.1) Correcting the intensity of the fluorescence images in two directions taken in step 4.5) according to the voltage signal obtained by the photodetector 5;

[0110] 5.2) According to the fitting relationship function X in step 2.1) F_img =f F (X,Y,Z) and X O_img =f O (X, Y, Z) and the light sheet position correction data saved in step 2.4) Project the fluorescence image obtained in step 4.5) into the physical coordinate system to obtain a fluorescence image of N×M pixels;

[0111] 5.3) dividing the N×M pixel fluorescence image projected in step 5.2) into multiple query windows of n×m pixels respectively;

[0112] 5.4) Calculate the fluorescence gray value integral I of the oxidant simulation solution in all query windows according to the following formula: O :

[0113]

[0114] Where i is the number of the query window in the X direction of the fluorescence image, j is the number of the query window in the Y direction of the fluorescence image, (I O ) i,j (X i ,Y j ) is the fluorescence gray value integral of the oxidant simulation liquid in the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescence image, (X i ,Y j) is the physical coordinate of the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescent image;

[0115] 5.5) Calculate the flow intensity of the oxidant simulation liquid in each query window according to the following formula:

[0116]

[0117] Among them, A i,j is the area of ​​the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescence image, m O is the total flow rate of the oxidant simulation liquid;

[0118] 5.6) Calculate the atomization mixing ratio of each query window to complete the measurement of the dynamic atomization mixing ratio distribution; specifically, calculate the atomization mixing ratio of each query window according to the following formula:

[0119]

[0120] Among them, g F (X i , Y j ) is the fuel simulation flow intensity for each query window, and its calculation method is the same as g O (X i , Y j ) is calculated in the same way.

[0121] The above five steps together constitute a method for measuring the dynamic atomization mixing ratio distribution, which can accurately measure the temporal and spatial distribution of the dynamic atomization mixing ratio of various types of liquid-liquid injectors 3.

[0122] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A system for measuring dynamic atomization mixing ratio distribution, characterized in that: It comprises a laser sheet light generating unit, an injector unit, a spectrometer (11), a trigger delay pulse signal generator (20), a clock delay pulse signal generator (21), a high-speed data acquisition device (22), a disturbance device (23), a continuous laser (19), software (24), a first optical observation device and a second optical observation device; The laser sheet light generating unit is used to emit laser light and form laser sheet light; The injector unit is used to inject an oxidant simulation liquid containing a first fluorescent dye (1) and a fuel simulation liquid containing a second fluorescent dye (2) toward the atomization cross-sectional area to be measured; The fluorescence wavelength distributions of the first fluorescent dye (1) and the second fluorescent dye (2) do not overlap; The spectrometer (11) is used to measure the fluorescence wavelength distribution and intensity of the first fluorescent dye (1) and the second fluorescent dye (2); The trigger delay pulse signal generator (20) is electrically connected to the high-speed data acquisition device (22), the first optical observation device, and the second optical observation device, respectively, and is used to send a TTL trigger signal to the high-speed data acquisition device (22), the first optical observation device, and the second optical observation device; The clock delay pulse signal generator (21) is electrically connected to the laser sheet light generating unit, the high-speed data acquisition device (22), the first optical observation device, and the second optical observation device, respectively, and is used to send an external clock signal to the laser sheet light generating unit, the high-speed data acquisition device (22), the first optical observation device, and the second optical observation device; The high-speed data acquisition instrument (22) is also electrically connected to the laser sheet light generating unit and the injector unit respectively, and is used to collect the laser intensity, the pre-injection pressure of the oxidant simulation liquid and the pre-injection pressure of the fuel simulation liquid; The disturbance device (23) is connected to the injector unit and is used to disturb the pre-injection pressure of the oxidant simulated liquid and the fuel simulated liquid; The continuous laser (19) is used to calibrate the background noise of the first optical observation device and the second optical observation device respectively; The first optical observation device and the second optical observation device are used to take fluorescent images of the atomized and mixed droplets from two different directions respectively; The software (24) is used to receive the fluorescent images of the atomized mixed droplets taken by the first optical observation device and the second optical observation device.

2. The system for measuring dynamic atomization mixing ratio distribution according to claim 1, characterized in that: It also includes a calibration target plate (18); the calibration target plate (18) is arranged in the atomization cross-sectional area to be measured and is used for collecting calibration images; the first optical observation device and the second optical observation device are respectively used to take calibration images of the calibration target plate (18) from two different directions; the software (24) is used to receive the calibration images of the calibration target plate (18) taken by the first optical observation device and the second optical observation device; The first fluorescent dye (1) is RH414 fluorescent dye; the second fluorescent dye (2) is rhodamine 590 fluorescent dye; The acquisition frequency of the high-speed data acquisition device (22) is 1-2MS / s; The trigger delay of the first optical observation device and the second optical observation device is no more than 1 μs, the filter wavelength range of the first optical observation device is 650nm-790nm, which is used to transmit the fluorescence of the wavelength of RH414 fluorescent dye, and the filter wavelength range of the second optical observation device is 550nm-570nm, which is used to transmit the fluorescence of the wavelength of rhodamine 590 fluorescent dye; The external clock delay of the clock delay pulse signal generator (21) is no greater than 1 μs; The disturbance frequency of the disturbance device (23) is not greater than 4000 Hz.

3. The system for measuring dynamic atomization mixing ratio distribution according to claim 2, characterized in that: The acquisition frequency of the high-speed data acquisition device (22) is 2MS / s.

4. The system for measuring dynamic atomization mixing ratio distribution according to claim 1, characterized in that: The laser sheet light generating unit comprises a high-frequency pulse laser (4) for emitting laser light, a photodetector (5) mounted on the high-frequency pulse laser (4), and a sheet light lens assembly (6) arranged on the laser light path; the laser frequency of the high-frequency pulse laser (4) is 40 kHz to 80 kHz, and the laser wavelength is 532 nm; the sheet light lens assembly (6) is used to form laser sheet light; The injector unit comprises an oxidant simulated liquid supply branch, a fuel simulated liquid supply branch, an injector (3), an automatic timing controller (7) and two pressure sensors (10); the oxidant simulated liquid supply branch and the fuel simulated liquid supply branch are connected to two inlets of the injector (3); the automatic timing controller (7) is electrically connected to a first valve (8) on the oxidant simulated liquid supply branch and a second valve (9) on the fuel simulated liquid supply branch respectively; the two pressure sensors (10) are connected to the injector (3) and are used to measure the pre-injection pressure of the oxidant simulated liquid and the fuel simulated liquid respectively; The first optical observation device comprises a first optical lens (14), a first filter group (12) and a first high-speed camera (16) which are arranged in sequence; the filtering wavelength range of the first filter group (12) is 650nm to 790nm; the second optical observation device comprises a second optical lens (15), a second filter group (13) and a second high-speed camera (17) which are arranged in sequence; the filtering wavelength range of the second filter group (13) is 550nm to 570nm; The first high-speed camera (16) and the second high-speed camera (17) are electrically connected to a trigger delay pulse signal generator (20); The clock delay pulse signal generator (21) is electrically connected to the high-frequency pulse laser (4), the high-speed data acquisition device (22), the first high-speed camera (16), and the second high-speed camera (17) respectively; The high-speed data acquisition device (22) is also electrically connected to the photoelectric detector (5) and the two pressure sensors (10) respectively; The disturbance device (23) is connected to the oxidant simulated liquid supply branch and the fuel simulated liquid supply branch; The continuous laser (19) is used to calibrate the background noise of the first high-speed photography (16) and the second high-speed photography (17) respectively; The software (24) is used to receive the fluorescent images of the atomized mixed droplets taken by the first high-speed camera (16) and the second high-speed camera (17).

5. A method for measuring dynamic atomization mixing ratio distribution, using the system for measuring dynamic atomization mixing ratio distribution according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Selection of fluorescence wavelength range; The fluorescence wavelength range is selected to achieve the distinction and simultaneous shooting of the fluorescence of the oxidant simulation liquid and the fluorescence of the fuel simulation liquid; 2) Correction of the projection position of the light sheet; the correction of the projection position of the light sheet is used to correct the position information of the laser light sheet; 3) Optimal background noise grayscale threshold correction; the optimal background noise grayscale threshold correction is used to improve the linearity of the relationship between fluorescence intensity and flow intensity; 4) Shooting of dynamic atomization fluorescence images of the injector; the dynamic atomization fluorescence images of the injector are used to obtain spatiotemporally synchronized fluorescence images of the atomization of the oxidant simulation liquid and the atomization fluorescence images of the fuel simulation liquid; 5) Calculation of atomization mixing ratio based on fluorescence images; the calculation of atomization mixing ratio based on fluorescence images is used to obtain the spatiotemporal distribution of the dynamic atomization mixing ratio through projection calculation.

6. The method for measuring dynamic atomization mixing ratio distribution according to claim 5, characterized in that: The steps of selecting the fluorescence wavelength range are specifically as follows: 1.1) The laser beam emitted by the high-frequency pulse laser (4) passes through the light sheet lens assembly (6) to form a laser sheet light; 1.2) irradiating the oxidant simulated liquid with laser light to generate a corresponding first fluorescence, irradiating the fuel simulated liquid with laser light to generate a corresponding second fluorescence, and using a spectrometer (11) to measure the wavelength distribution of the first fluorescence and the second fluorescence respectively; 1.3) Determining the wavelengths of the first filter set (12) and the second filter set (13) based on the measured wavelength distributions of the first fluorescence and the second fluorescence.

7. The method for measuring dynamic atomization mixing ratio distribution according to claim 6, characterized in that: The steps of correcting the projection position of the light sheet are specifically as follows: 2.1) placing the calibration target plate (18) in the atomization cross-section area to be measured, determining the zero point and the X direction, Y direction, and Z direction of the physical coordinate system, using the first high-speed photography (16) and the second high-speed photography (17) to obtain calibration images of the calibration target plate (18) respectively, and calculating the oxidant fluorescence image projection fitting relationship function X between the image coordinate system and the physical coordinate system of the calibration images in different directions O_img =f O (X, Y, Z) and the fuel fluorescence image projection fitting function X F_img =f F (X, Y, Z), and then derive the aberration formula of the Z-direction projection image based on the fitting relationship function: Among them, X F_img and X O_img Calibrate the coordinates of the image in the image coordinate system in two directions, dX F -dX o is the image difference between the projected images in two directions, dZ is the distance between the real physical plane and the projection plane, f O The partial derivative of (X,Y,Z) in the Z direction, f F The partial derivative of (X,Y,Z) in the Z direction, f O The partial derivative of (X,Y,Z) in the X direction, f F The partial derivative of (X,Y,Z) in the X direction; 2.2) adjusting the laser sheet light to a plane position that overlaps with the calibration target plate (18) as much as possible, controlling the distance between the laser sheet light and the Z=0 plane of the calibration target plate (18) to be within 2 mm, then removing the calibration target plate (18) and capturing a fluorescent image of the atomized droplets; 2.3) According to the fluorescence image of the atomized droplet, according to the fitting relationship function of step 2.1), get Perform the k-th projection image calculation in two directions, where dZ0=0; 2.4) Use the cross-correlation algorithm to calculate the difference dX between the projection images in two directions F -dX o If the aberration is greater than 0.2 mm, change the aberration dX F -dX o Substitute the data into the aberration formula derived in step 2.1) to calculate the k-th Z-direction position information correction value dZ k , Return to 2.3) and perform k+1 times of sheet light position correction calculation. If the aberration is less than 0.2 mm, it means The sheet light position correction is in place and the sheet light position correction data is saved As the Z-direction position information for subsequent fluorescence image projection.

8. The method for measuring dynamic atomization mixing ratio distribution according to claim 7, characterized in that: The steps of correcting the optimal background noise grayscale threshold are specifically as follows: 3.1) using different exposure times for the first high-speed photography (16) and the second high-speed photography (17), respectively, to photograph the light spot formed by the laser irradiation emitted by the continuous laser (19); 3.2) Perform linear regression on the spot intensity and exposure time to obtain the optimal background noise grayscale threshold.

9. The method for measuring dynamic atomization mixing ratio distribution according to claim 8, characterized in that: The steps of shooting the dynamic atomization fluorescence image of the injector are specifically as follows: 4.1) Installing the first filter set (12) and the second filter set (13) determined in step 1.3) between the first high-speed camera (16) and the first optical lens (14), and between the second high-speed camera (17) and the second optical lens (15); 4.2) setting the grayscale threshold of the first high-speed photography (16) and the second high-speed photography (17) to the optimal background noise grayscale threshold determined in step 3.2); 4.3) The automatic timing controller (7) opens the first valve (8) and the second valve (9) at the same time, and the oxidant simulated liquid and the fuel simulated liquid are sprayed out through the injector (3) and then atomized and mixed to form an atomization zone, and the disturbance device (23) is started to simultaneously apply disturbances of different frequencies to the oxidant simulated liquid supply pipeline and the fuel simulated liquid supply pipeline; 4.4) The high-frequency pulse laser (4) emits a laser beam, which passes through the light sheet lens assembly (6) to form a laser sheet light; the laser sheet light irradiates the atomized area and excites the atomized area to generate fluorescence; 4.5) The first high-speed camera (16) and the second high-speed camera (17) take fluorescent images of the atomized area from two directions respectively.

10. The method for measuring dynamic atomization mixing ratio distribution according to claim 9, characterized in that: The steps of calculating the atomization mixing ratio based on the fluorescence image are specifically as follows: 5.1) According to the voltage signal obtained by the photodetector (5), the intensity of the fluorescence image in two directions taken in step 4.5) is corrected; 5.2) According to the fitting relationship function X in step 2.1) F_img =f F (X,Y,Z) and X O_img =f O (X, Y, Z) and the light sheet position correction data saved in step 2.4) Project the fluorescence image obtained in step 4.5) into the physical coordinate system to obtain a fluorescence image of N×M pixels; 5.3) dividing the N×M pixel fluorescence image projected in step 5.2) into multiple query windows of n×m pixels respectively; 5.4) Calculate the fluorescence gray value integral I of the oxidant simulation solution in all query windows according to the following formula: O : in, i is the number of the query window in the X direction of the fluorescence image, j is the number of the query window in the Y direction of the fluorescence image, (I O ) i,j (X i ,Y j ) is the fluorescence gray value integral of the oxidant simulation liquid in the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescence image, (X i ,Y j ) is the physical coordinate of the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescent image; 5.5) Calculate the flow intensity of the oxidant simulation liquid in each query window according to the following formula: Among them, A i,j is the area of ​​the query window with sequence number i in the X direction and sequence number j in the Y direction of the fluorescence image, m O is the total flow rate of the oxidant simulation liquid; 5.6) Calculate the atomization mixing ratio of each query window to complete the measurement of the dynamic atomization mixing ratio distribution; specifically, calculate the atomization mixing ratio of each query window according to the following formula: Among them, g F (X i , Y j ) is the fuel simulation flow intensity for each query window, and its calculation method is the same as g O (X i , Y j ) is calculated in the same way.

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