A system and method for measuring dynamic atomization mixture ratio distribution

Abstract

The application provides a system and method for measuring dynamic atomization mixing ratio distribution, which can solve the problem that the existing measurement method is not applicable to the measurement of dynamic atomization mixing ratio under high characteristic frequency, and the problem of large measurement error caused by the existence of overlapping between the wave bands of two fluorescent dyes. The method comprises the following steps: fluorescent wavelength range selection, which is used for realizing the differentiation and simultaneous shooting of the fluorescence of the oxidant simulation liquid and the fluorescence of the fuel simulation liquid; sheet light projection position correction, which is used for realizing the correction of the laser sheet light position information; optimal background noise gray threshold correction, which is used for improving the linearity of the relationship between the fluorescence intensity and the flow intensity; injection atomization fluorescent image shooting, which is used for obtaining the time-space synchronized atomization fluorescent images of the oxidant simulation liquid and the fuel simulation liquid; and atomization mixing ratio calculation based on the fluorescent images, which is used for obtaining the time-space distribution of the dynamic atomization mixing ratio through projection calculation.

Description

TECHNICAL FIELD

[0001] The present application relates to how to measure the atomization mixture ratio distribution of an engine injector, and in particular to a system and method for measuring dynamic atomization mixture ratio distribution. BACKGROUND

[0002] Liquid propellant atomization is the premise of liquid rocket engine combustion, and the liquid propellant includes fuel and oxidizer. In the atomization process, the atomization mixture ratio of the oxidizer and the 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 kind of dynamic atomization. This dynamic atomization will in turn be coupled 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, it is of great significance to study the atomization mixture characteristics of the injector under pressure disturbance conditions for improving the specific impulse performance and reliability of the engine.

[0003] Since the measurement object is the cold-state spray field of the engine injector, the contact-type measurement method will seriously interfere with the measurement object, and therefore the non-contact-type measurement method is usually used for measurement. The existing non-contact-type measurement method is mainly the laser-induced fluorescence method, that is, two different fluorescent dyes are added to the oxidizer and the fuel, a high-speed camera is used to shoot the fluorescent image, and the atomization mixture ratio is calculated according to the light intensity of the fluorescent image. However, the existing laser-induced fluorescence method is not suitable for measuring the dynamic atomization mixture ratio under high characteristic frequency, and the fluorescent wave bands of the rhodamine 610 and rhodamine 590 fluorescent dyes used in the measurement process overlap, resulting in a large measurement error. SUMMARY

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

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A system for measuring dynamic atomization mixture ratio distribution, characterized in that it comprises 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 spray the oxidant simulation liquid containing the first fluorescent dye and the fuel simulation liquid containing the second fluorescent dye to the atomization cross-section area to be measured; the fluorescent wavelength distribution of the first fluorescent dye and the second fluorescent dye does not coincide;

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

[0010] The trigger delay pulse signal generator is electrically connected with the high-speed data acquisition instrument, the first optical observation device and the second optical observation device respectively, and is used to send the 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 with 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 the 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 further electrically connected with 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 perturbation device is connected with the injector unit, and is used to exert perturbation on the pre-injection pressure of the oxidant simulation liquid and the fuel simulation 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 respectively used to shoot the fluorescent images of the atomized mixed liquid droplets from two different directions;

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

[0017] Further, a calibration target plate is further included; the calibration target plate is arranged in the atomization cross-section area to be measured, and is used to calibrate the image collection; the first optical observation device and the second optical observation device are respectively used to shoot the calibration images of the calibration target plate from two different directions; and the software is used to receive the calibration images of the calibration target plate shot by the first optical observation device and the second optical observation device;

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

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

[0020] The trigger delay of the first optical observation device and the second optical observation device is not greater than 1 μs, the filter wavelength range of the first optical observation device is 650 nm-790 nm, and the filter wavelength range is used to transmit the fluorescence wavelength of RH414 fluorescent dye; the filter wavelength range of the second optical observation device is 550 nm-570 nm, and the filter wavelength range is used to transmit the fluorescence wavelength of rhodamine 590 fluorescent dye;

[0021] The external clock delay of the clock delay pulse signal generator is not greater than 1 μs;

[0022] The disturbance frequency of the disturbance device is not greater than 4000 Hz.

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

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

[0025] The injector unit comprises an oxidizing agent simulation liquid supply branch, a fuel simulation liquid supply branch, an injector, an automatic timing controller, and two pressure sensors; the oxidizing agent simulation liquid supply branch and the fuel simulation liquid supply branch are connected with two inlets of the injector; the automatic timing controller is electrically connected with a first valve on the oxidizing agent simulation liquid supply branch and a second valve on the fuel simulation liquid supply branch, respectively; the two pressure sensors are connected on the injector and are used to measure the pre-injection pressure of the oxidizing agent simulation liquid and the fuel simulation 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 650 nm-790 nm; 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 550 nm-570 nm;

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

[0028] The clock delay pulse signal generator is electrically connected with 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 with the photodetector and the two pressure sensors, respectively.

[0030] The disturbance device is connected with an oxidant simulation liquid supply branch and a fuel simulation liquid supply branch;

[0031] The continuous laser is used for background noise calibration of the first high-speed photography and the second high-speed photography respectively.

[0032] The software is used for receiving the fluorescence images of the atomized mixed liquid droplets photographed by the first high-speed photography and the second high-speed photography.

[0033] Meanwhile, the application also provides a method for measuring dynamic atomization mixing ratio distribution, which adopts the system for measuring dynamic atomization mixing ratio distribution, and is characterized by comprising the following steps:

[0034] 1) fluorescence wavelength range selection; the fluorescence wavelength range selection is used for realizing the differentiation and simultaneous shooting of the oxidant simulation liquid fluorescence and the fuel simulation liquid fluorescence;

[0035] 2) sheet light projection position correction; the sheet light projection position correction is used for realizing the correction of the laser sheet light position information;

[0036] 3) optimal background noise gray threshold correction; the optimal background noise gray threshold correction is used for improving the linearity of the relationship between the fluorescence intensity and the flow intensity;

[0037] 4) injector dynamic atomization fluorescence image shooting; the injector dynamic atomization fluorescence image shooting is used for obtaining the time-space synchronous oxidant simulation liquid atomization fluorescence image and fuel simulation liquid atomization fluorescence image;

[0038] 5) atomization mixing ratio calculation based on fluorescence image; the atomization mixing ratio calculation based on fluorescence image is used for obtaining the time-space distribution of the dynamic atomization mixing ratio through projection calculation.

[0039] Further, the step of the fluorescence wavelength range selection specifically comprises:

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

[0041] 1.2) the laser sheet light irradiates the oxidant simulation liquid to generate corresponding first fluorescence, and irradiates the fuel simulation liquid to generate corresponding second fluorescence, and a spectrometer is used for measuring the wavelength distribution of the first fluorescence and the second fluorescence respectively;

[0042] 1.3) according to the measured wavelength distribution of the first fluorescence and the second fluorescence, the wavelength of the first filter set and the second filter set is determined.

[0043] Further, the step of the sheet light projection position correction specifically comprises:

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

[0045]

[0046] Wherein, X F_img and X O_img are the coordinates of the two direction calibration images in the image coordinate system, dX F -dX o is the aberration between the two direction projection images, dZ is the distance between the real physical plane and the projection plane, is the partial derivative of f O (X,Y,Z) in the Z direction, is the partial derivative of f F (X,Y,Z) in the Z direction, is the partial derivative of f O (X,Y,Z) in the X direction, is the partial derivative of f F (X,Y,Z) in the X direction;

[0047] 2.2) Adjust the laser sheet light to the plane position as much as possible coinciding with the calibration target disk, control the distance between the laser sheet light and the Z=0 plane of the calibration target disk within 2mm, then remove the calibration target disk, and shoot the atomization droplet fluorescence image;

[0048] 2.3) According to the atomization droplet fluorescence image, take according to the fitting relationship function of step 2.1), and perform the kth projection image calculation in two directions, wherein dZ0=0;

[0049] 2.4) Use the cross-correlation algorithm to calculate the aberration dX F -dX o between the projection images in two directions, if the aberration is greater than 0.2mm, substitute the aberration dX F -dX o data into the aberration formula derived in step 2.1) to calculate the Z direction position information correction value dZ k of the kth time, Returning to 2.3), k+1 times of sheet light position correction calculation is performed, if the aberration is less than 0.2mm, it means that the sheet light position correction is in place, save the sheet light position correction data as the Z direction position information of the subsequent fluorescent image projection.

[0050] Further, the step of the optimal background noise gray threshold correction is specifically:

[0051] 3.1) Different exposure times are used for the first high-speed photography and the second high-speed photography respectively to shoot the light spots formed by the laser emitted by the continuous laser;

[0052] 3.2) Linear regression is performed on the light spot intensity and the exposure time to obtain the optimal background noise gray threshold.

[0053] Further, the step of the jet injector dynamic atomization fluorescent image shooting is specifically:

[0054] 4.1) The first filter set and the second filter set determined in step 1.3) are correspondingly installed between the first high-speed photography and the first optical lens, and between the second high-speed photography and the second optical lens;

[0055] 4.2) The gray threshold values of the first high-speed photography and the second high-speed photography are set as the optimal background noise gray threshold determined in step 3.2);

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

[0057] 4.4) The high-frequency pulsed laser emits a laser beam, which forms a laser sheet light through the sheet light lens assembly; the laser sheet light irradiates the atomization area and excites to generate fluorescence;

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

[0059] Further, the step of the atomization mixing ratio calculation based on the fluorescent image is specifically:

[0060] 5.1) According to the voltage signal obtained by the photodetector, the intensities of the fluorescent images in two directions shot in step 4.5) are corrected;

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

[0062] 5.3) Divide the N x M pixel fluorescence image projected in step 5.2) into a plurality of query windows of n x m pixels, respectively;

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

[0064]

[0065] wherein i is the serial number of the query window in the X direction of the fluorescence image, j is the serial 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 serial number i in the X direction and serial number j in the Y direction of the fluorescence image, (X i ,Y j ) is the physical coordinate of the query window with serial number i in the X direction and serial number j in the Y direction;

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

[0067]

[0068] wherein A i,j is the area of the query window with serial number i in the X direction and serial number j in the Y direction of the fluorescence image, m O is the total flow 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] wherein g F (X i , Y j ) is the fuel simulation liquid flow intensity of each query window, and the calculation method is the same as that of g O (X i , Y j ).

[0072] The beneficial effects of the present application are:

[0073] 1. The application 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, high-speed dynamic measurement of the injector propellant atomization mixing ratio distribution under 0Hz-4000Hz pressure disturbance is realized in a non-contact manner. The method is suitable for the measurement of dynamic atomization mixing ratio under high characteristic frequency, and the measurement accuracy of the atomization mixing ratio can be improved because the selected first fluorescent dye and second fluorescent dye have non-overlapping fluorescent wavelength distribution and obvious demarcation.

[0074] 2. In the application, the collection 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 not greater than 1us, and the external clock delay of the clock delay pulse signal generator is not greater than 1us, so that the synchronization error of the system of the application is not greater than 1us, and the phase angle error of the sampling rate of the system is not greater than 1.8°.

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

[0076] Figure 1 is a structural schematic diagram of an embodiment of the system for measuring dynamic atomization mixing ratio distribution of the application;

[0077] Figure 2 is the fluorescence spectrum of RH414 fluorescent dye and rhodamine 590 fluorescent dye in an embodiment of the system for measuring dynamic atomization mixing ratio distribution of the application;

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

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

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

[0081] BRIEF DESCRIPTION OF DRAWINGS

[0082] 1-first fluorescent dye, 2-second fluorescent dye, 3-injector, 4-high-frequency pulse laser, 5-photodetector, 6-lens assembly, 7-automatic timing controller, 8-first valve, 9-second valve, 10-pressure sensor, 11-spectrometer, 12-first filter set, 13-second filter set, 14-first optical lens, 15-second optical lens, 16-first high-speed camera, 17-second high-speed camera, 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 Figures 1-2 As shown, a system for measuring dynamic atomization mixing ratio distribution includes a laser sheet light generating unit, an injector unit, a calibration target disk 18, 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. 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 light sheet lens assembly 6 arranged in the laser light path. The high-frequency pulse laser 4 has a laser frequency of 40 kHz to 80 kHz and a laser wavelength of 532 nm. The light sheet lens assembly 6 is used to form the laser light sheet.

[0084] The injector unit includes an oxidizer simulant liquid supply branch, a fuel simulant liquid supply branch, an injector 3, an automatic timing controller 7, and two pressure sensors 10. The oxidizer simulant liquid supply branch and the fuel simulant liquid supply branch are connected to the two inlets of the injector 3. The injector 3 is used to spray an oxidizer simulant liquid containing a first fluorescent dye 1 and a fuel simulant liquid containing a second fluorescent dye 2 into the atomized cross-section to be measured. The fluorescence wavelength distributions of the first fluorescent dye 1 and the second fluorescent dye 2 do not overlap. The automatic timing controller 7 is electrically connected to a first valve 8 on the oxidizer simulant liquid supply branch and a second valve 9 on the fuel simulant liquid supply branch, respectively. Two pressure sensors 10 are connected to the injector 3 and are used to measure the pre-spray pressure of the oxidizer simulant liquid and the fuel simulant liquid, respectively. A calibration target 18 is placed within the atomized cross-section to be measured for calibration image acquisition. A 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 comprises a first optical lens 14, a first filter set 12 and a first high-speed camera 16 arranged in sequence. The second optical observation device comprises a second optical lens 15, a second filter set 13 and a second high-speed camera 17 arranged in sequence. The first high-speed camera 16 and the second high-speed camera 17 are respectively used for shooting calibration images of the calibration target plate 18 and fluorescent images of the atomized mixed liquid 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 filter wavelength range of the first filter set 12 is 650 nm-790 nm, which is used for transmitting the fluorescent wavelength of the RH414 fluorescent dye. The filter wavelength range of the second filter set 13 is 550 nm-570 nm, which is used for transmitting the fluorescent wavelength of the rhodamine 590 fluorescent dye.

[0086] The trigger delay pulse signal generator 20 is electrically connected with the high-speed data acquisition instrument 22, the first high-speed camera 16 and the second high-speed camera 17, and is used for sending 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 with 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, and is used for sending 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 1 μs. The high-speed data acquisition instrument 22 is also electrically connected with the photoelectric detector 5 and the two pressure sensors 10, and is used for collecting the laser intensity, the pre-injection pressure of the oxidant simulation liquid and the pre-injection pressure of the fuel simulation liquid. The collection frequency of the high-speed data acquisition instrument 22 is 1-2 MS / s. The collection frequency of the high-speed data acquisition instrument 22 in the embodiment is 2 MS / s. The disturbance device 23 is connected with the oxidant simulation liquid supply branch and the fuel simulation liquid supply branch, and is used for applying disturbance to the pre-injection pressure of the oxidant simulation liquid and the fuel simulation liquid. The disturbance frequency of the disturbance device 23 is not greater than 4000 Hz. The continuous laser 19 is used for background noise calibration of the first high-speed camera 16 and the second high-speed camera 17. The software 24 is used for receiving the calibration images of the calibration target plate 18 and the fluorescent images of the atomized mixed liquid droplets shot by the first high-speed camera 16 and the second high-speed camera 17.

[0087] As shown in Figures 3-5 The embodiment also provides a method for measuring a dynamic atomization mixing ratio distribution, which adopts the system for measuring a dynamic atomization mixing ratio distribution and comprises the following steps:

[0088] 1) Selection of a fluorescent wavelength range; the selection of the fluorescent wavelength range is used for realizing the differentiation and simultaneous shooting of the oxidant simulation liquid fluorescence and the fuel simulation liquid fluorescence; specifically,

[0089] 1.1) The laser beam emitted by the high-frequency pulsed laser 4 forms a laser sheet through the sheet lens assembly 6;

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

[0091] 1.3) According to the wavelength distribution of the measured first fluorescence and second fluorescence, the wavelength of the first filter set 12 and the second filter set 13 is determined.

[0092] 2) Sheet projection position correction; the sheet projection position correction is used to correct the laser sheet position information; specifically:

[0093] 2.1) Place the calibration target disc 18 in the atomization cross-section area to be measured to determine the zero point and X direction, Y direction, Z direction of the physical coordinate system. The first high-speed camera 16 and the second high-speed camera 17 are used to obtain the calibration images of the calibration target disc 18 respectively, and the fitting relationship function X O_img = f O (X, Y, Z) of the oxidant fluorescence image and the fitting relationship function X F_img = f F (X, Y, Z) of the fuel fluorescence image between the image coordinate system and the physical coordinate system are calculated, and then the aberration formula of the Z direction projection image is derived according to the fitting relationship function:

[0094]

[0095] Wherein, X F_img and X O_img are the coordinates of the two direction calibration images in the image coordinate system, dX F -dX o is the aberration between the two direction projection images, dZ is the distance between the real physical plane and the projection plane, is the partial derivative of f O (X, Y, Z) in the Z direction, is the partial derivative of f F (X, Y, Z) in the Z direction, is the partial derivative of f O (X, Y, Z) in the X direction, is the partial derivative of f F (X, Y, Z) in the X direction;

[0096] 2.2) Adjust the laser sheet to the plane position as much as possible coinciding with the calibration target disc 18, control the distance between the laser sheet and the Z=0 plane of the calibration target disc 18 within 2mm, then remove the calibration target disc 18, and take the atomized droplet fluorescence image;

[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 0.2mm, it means The sheet light position is corrected and the sheet light position correction data is saved. As the Z-direction position information of the 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 flux intensity; specifically:

[0100] 3.1) Using different exposure times for the first high-speed photograph 16 and the second high-speed photograph 17, respectively, to capture 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) Injector dynamic atomization fluorescence image capture; Injector dynamic atomization fluorescence image capture is used to obtain spatiotemporally synchronized oxidant simulating liquid atomization fluorescence images and fuel simulating liquid atomization fluorescence images; 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, respectively;

[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 simultaneously, and the oxidant simulant and the fuel simulant are injected through the injector 3 to form an atomization zone, and the disturbance device 23 is started to apply different frequency disturbances to the oxidant simulant supply line and the fuel simulant supply line simultaneously;

[0106] 4.4) The high-frequency pulsed laser 4 emits a laser beam, and the laser beam forms a laser sheet through the sheet lens assembly 6; the laser sheet irradiates the atomization zone and excites fluorescence;

[0107] 4.5) The first high-speed camera 16 and the second high-speed camera 17 respectively capture the fluorescence images of the atomization zone from two directions.

[0108] 5) Fluorescence image-based atomization mixing ratio calculation; the fluorescence image-based atomization mixing ratio calculation is used to obtain the time-space distribution of the dynamic atomization mixing ratio by projection calculation; specifically:

[0109] 5.1) According to the voltage signal obtained by the photodetector 5, the intensity of the fluorescence images in the two directions captured in step 4.5) is corrected;

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

[0111] 5.3) The N×M pixel fluorescence images projected in step 5.2) are respectively divided into n×m pixel query windows;

[0112] 5.4) The fluorescence gray value integral I O of the oxidant simulant of all query windows is respectively calculated according to the following formula:

[0113]

[0114] Where i is the serial number of the query window in the X direction of the fluorescence image, j is the serial number of the query window in the Y direction of the fluorescence image, and (I O ) i,j (X i ,Y j ) is the fluorescence gray value integral of the oxidant simulant in the query window with serial number i in the X direction and serial number j in the Y direction of the fluorescence image, and (X i ,Y j ​) is the area of the query window with X direction sequence number i and Y direction sequence number j, m

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

[0116]

[0117] wherein, A i,j is the area of the query window with X direction sequence number i and Y direction sequence number j, m O is the total flow of the oxidant simulation liquid;

[0118] 5.6) The atomization mixing ratio of each query window is calculated, and the measurement of the dynamic atomization mixing ratio distribution is completed; the atomization mixing ratio of each query window is calculated according to the following formula:

[0119]

[0120] wherein, g F (X i , Y j ) is the flow intensity of the fuel simulation liquid of each query window, and the calculation method is the same as that of g O (X i , Y j ).

[0121] The above five steps jointly constitute the method for measuring the dynamic atomization mixing ratio distribution, and the time-space distribution of the dynamic atomization mixing ratio of each type of liquid-liquid injector 3 can be accurately measured.

[0122] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited to this. Any change or replacement within the technical scope disclosed by the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A system for measuring dynamic atomization mixing ratio distribution, characterized by: The device 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) into 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 device (22) is also electrically connected to the laser sheet light generating unit and the injector unit, 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 respectively capture fluorescent images of the atomized and mixed droplets from two different directions; 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-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 capture 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) captured 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 triggering 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 to 790nm, and is used to transmit the fluorescence of the wavelength of the RH414 fluorescent dye, and the filter wavelength range of the second optical observation device is 550nm to 570nm, and is used to transmit the fluorescence of the wavelength of the rhodamine 590 fluorescent dye; The external clock delay of the clock delay pulse signal generator (21) is no more 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 40kHz to 80kHz, and the laser wavelength is 532nm; the sheet light lens assembly (6) is used to form the laser sheet light; The injector unit comprises 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); the oxidant simulating liquid supply branch and the fuel simulating 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 simulating liquid supply branch and a second valve (9) on the fuel simulating liquid supply branch respectively; the two pressure sensors (10) are connected to the injector (3) and are used to measure the pre-injection pressures of the oxidant simulating liquid and the fuel simulating 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) 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) 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). 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). The software (24) is used to receive the fluorescent images of the atomized and 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 capture of the fluorescence of the oxidant simulating liquid and the fluorescence of the fuel simulating liquid; 2) Correction of the light sheet projection position; the light sheet projection position correction is used to correct the laser light sheet position information; 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 flux intensity; 4) dynamic atomization fluorescence image capture of the injector; the dynamic atomization fluorescence image capture of the injector is used to obtain spatiotemporally synchronized fluorescence images of the oxidant simulating liquid atomization and the fuel simulating liquid atomization; 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 light sheet; 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 measuring the wavelength distribution of the first fluorescence and the second fluorescence respectively using a spectrometer (11); 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 sheet light projection position are specifically as follows: 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), and calculate the oxidant fluorescence image projection fitting relationship function X between the image coordinate system and the physical coordinate system for 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 two projected images, 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 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 disk (18) as much as possible, and controlling the distance between the laser sheet light and the Z=0 plane of the calibration target disk (18) to be within 2 mm, then removing the calibration target disk (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 0.2mm, it means The sheet light position is corrected and the sheet light position correction data is saved. As the Z-direction position information of the 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 camera (16) and the second high-speed camera (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 photograph (16) and the second high-speed photograph (17) to the optimal background noise grayscale threshold determined in step 3.2); 4.3) The automatic timing controller (7) simultaneously opens the first valve (8) and the second valve (9), and the oxidant simulated liquid and the fuel simulated liquid are sprayed out through the injector (3) and atomized and mixed to form an atomization area. The disturbance device (23) is activated 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 it to produce 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) Correcting the intensity of the fluorescence images in two directions captured in step 4.5) based on the voltage signal obtained by the photodetector (5); 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 each; 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 serial number of the query window in the X direction of the fluorescence image, j is the serial 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 ) are the physical coordinates of the query window numbered i in the X direction and j in the Y direction of the fluorescent image; 5.5) Calculate the flow intensity of the oxidant simulant 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 simulating 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.

Images