Method and system for measuring kerosene atomization gas-liquid two-phase concentration in coupled gas inlet state

Abstract

The invention discloses a kerosene atomization gas-liquid two-phase concentration measurement method and system in a coupled gas inlet state. The method comprises the following steps: regulating and controlling a liquid-phase fluorescence camera to delay shooting of a to-be-measured spray section relative to a gas-phase fluorescence camera; when the oil injection pressure of the oil injector is reduced to the set pressure intensity, a liquid-phase fluorescence original image and a gas-phase fluorescence original image are synchronously collected; performing image processing on the liquid-phase fluorescence original image and the gas-phase fluorescence original image, and extracting contour information of the liquid-phase fuel oil and the gas-phase fuel oil; the fluorescence intensity of each pixel is counted in the contour information of the liquid-phase fuel oil and the gas-phase fuel oil, and the gas-liquid two-phase concentration distribution of the spray section to be detected is obtained through the established linear relation between the fluorescence intensity and the fuel oil steam concentration gas phase and the established linear relation between the fluorescence intensity and the liquid drop concentration; according to the scheme, a'spectrum-time two-dimensional separation 'strategy is innovatively adopted, higher-purity signal separation is guaranteed on the premise that enough signal intensity is guaranteed, and the gas-liquid two-phase concentration measurement accuracy is improved.

Description

Technical Field

[0001] This invention relates to the field of kerosene atomized gas-liquid two-phase concentration measurement technology, specifically to a method and system for measuring the concentration of kerosene atomized gas-liquid two-phase under coupled air intake conditions. Background Technology

[0002] As core power plants in modern aviation and energy sectors, aero-engines and heavy-duty gas turbines directly impact national security and economic lifelines through their performance, efficiency, and emission levels. The combustion chamber, the heart of the power plant, is the site of an extremely complex multiphase, transient, and turbulent physicochemical process involving fuel atomization, evaporation, air mixing, and ultimately, combustion and heat release. The initial droplet size and spatial distribution, along with the fuel vapor concentration distribution, of the atomized liquid fuel spray field formed by the nozzles collectively constitute the initial boundary conditions for combustion, fundamentally determining the stability and completeness of the subsequent combustion process and the generation levels of pollutants (such as soot and NOx). Therefore, achieving accurate measurement of the fuel spray field within the combustion chamber, especially the gas (fuel vapor) and liquid (droplet) two-phase distribution, is a crucial prerequisite for understanding the fundamental physical mechanisms of combustion, validating numerical models, and ultimately optimizing combustion chamber design.

[0003] However, achieving accurate measurement of the spray field under real engine operating conditions faces extremely demanding technical challenges. First, the internal environment of a real combustion chamber is characterized by high temperatures (up to 2000K and above) and high pressures (several megapascals). Furthermore, to achieve stable flame and efficient combustion, a strong swirling field is typically created, placing the fuel spray in an extremely complex and unsteady "coupled intake" aerodynamic environment. In this environment, the evaporation, breakup, collision, and fuel-air mixing processes of droplets are coupled and constantly changing, requiring measurement techniques with extremely high temporal resolution (microseconds or even nanoseconds) and spatial resolution (micrometers) to "freeze" and analyze these transient fine structures.

[0004] Secondly, the physical characteristics of the oil-gas two-phase mixture field present fundamental challenges. The liquid phase (droplets, filaments, liquid films) and the gas phase (fuel vapor) are spatially intertwined and coexist. Currently, laser-induced fluorescence (LIF) technology is gradually becoming a powerful tool for studying spray fields. Among them, planar laser-induced fluorescence technology can achieve two-dimensional concentration field measurement of specific components (such as fuel vapor).

[0005] However, conventional LIF technology, if using only a single fluorescent tracer, suffers from significant tailing and overlap between the fluorescence spectra of the gas phase (tetramethyl-p-phenylenediamine TMPD monomer) and the liquid phase (tetramethyl-p-phenylenediamine TMPD: naphthalene Np complex). The fluorescence spectra of the gas and liquid phases are not ideally orthogonal, but rather exhibit tailing phenomena on both sides of their respective main peaks, leading to "spectral crosstalk." Furthermore, the difference in fluorescence lifetime between the two phases is limited (especially under high temperature and high pressure conditions, the lifetimes shorten and converge). A single-dimensional approach cannot effectively decouple them, resulting in severe crosstalk. Summary of the Invention

[0006] The purpose of this invention is to provide a method and system for measuring the concentration of kerosene atomized gas and liquid phases under coupled air intake conditions, in order to solve the technical problem that the fluorescence spectra of the gas and liquid phases in the prior art are not ideally orthogonal, but have a tailing phenomenon on both sides of their respective main peaks, resulting in "spectral crosstalk". Single-dimensional methods cannot effectively decouple the phases, leading to severe crosstalk.

[0007] To solve the above-mentioned technical problems, the present invention specifically provides the following technical solution:

[0008] A kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake conditions includes:

[0009] The injector introduces a liquid mixture of base fuel and fluorescent tracer into its inlet.

[0010] The laser source includes a gas phase laser source and a liquid phase laser source. The direction of the laser is adjusted by a dichroic mirror, and the laser with the adjusted direction illuminates the spray section of the injector to be tested through an optical path system.

[0011] The image acquisition system includes a gas phase fluorescence camera and a liquid phase fluorescence camera, with an opening facing the inlet direction of the fuel injector, and a dichroic mirror is provided at the intersection of the gas phase fluorescence camera and the liquid phase fluorescence camera, so that the gas phase fluorescence camera can capture and acquire gas phase fluorescence signals, and the liquid phase fluorescence camera can capture and acquire liquid phase fluorescence signals.

[0012] A timing controller is communicatively connected to the image acquisition system and the laser source. The timing controller is used to control the triggering timing of the laser source and the image acquisition system so that the time points for receiving the liquid fluorescence signal and receiving the gas fluorescence signal have a relative delay signal, so as to separate the gas fluorescence signal and the liquid fluorescence signal.

[0013] The data processing system is used to process the gas phase fluorescence raw image and liquid phase fluorescence raw image acquired by the image acquisition system, and to count the fluorescence intensity of each pixel in the spray area of ​​the gas phase fluorescence raw image and liquid phase fluorescence raw image. Based on the relationship between fluorescence intensity and fuel vapor concentration in the gas phase and liquid droplet phase, the gas-liquid two-phase concentration distribution of the spray section to be tested is obtained.

[0014] As a preferred embodiment of the present invention, the gas phase laser source and the liquid phase laser source are distributed in a vertical direction, and the gas phase laser source and the liquid phase laser source are transmitted in the same horizontal direction through a dichroic mirror. The gas phase laser source and the liquid phase laser source are disposed on the side of the test spray path formed by the mixture of base fuel and fluorescent tracer liquid.

[0015] The gas phase laser source outputs 266nm laser light, and the liquid phase laser source outputs 532nm laser light.

[0016] The dichroic mirror reflects the gas phase laser and transmits the liquid phase laser.

[0017] As a preferred embodiment of the present invention, the optical path system includes a first quartz cylindrical lens for receiving the laser light source, and a second concave quartz lens and a third quartz cylindrical lens disposed between the first quartz cylindrical lens and the fuel injector.

[0018] The lasers emitted by the gas phase laser source and the liquid phase laser source pass through the first quartz cylindrical lens, the second concave quartz lens and the third quartz cylindrical lens in sequence, forming a sheet-like laser below the nozzle of the injector to illuminate the spray section of the injector to be tested.

[0019] As a preferred embodiment of the present invention, the base fuel is n-undecane (C 11 H 24 The fluorescent tracers selected are tetramethyl-p-phenylenediamine (TMPD) and naphthalene (Np).

[0020] p-Tetramethyl-p-phenylenediamine (TMPD): Naphthalene (Np): n-Undecane (C 11 H 24 The ratio is 1:9:90.

[0021] In a preferred embodiment of the present invention, the gas phase fluorescence camera and the liquid phase fluorescence camera are non-coaxially distributed;

[0022] The gas fluorescence camera is equipped with a 300nm-400nm bandpass filter and is used to capture the fluorescence of tetramethyl-p-phenylenediamine (TMPD) monomer.

[0023] The liquid fluorescence camera is equipped with a 410nm-490nm bandpass filter and a superimposed 532nm notch filter. The liquid fluorescence camera is used to capture the fluorescence of the tetramethyl-p-phenylenediamine (TMPD)-naphthalene (Np) complex and filter out the 532nm laser.

[0024] As a preferred embodiment of the present invention, the timing controller simultaneously excites the gas phase laser source and the liquid phase laser source to form laser pulses, and the timing controller adjusts the liquid phase fluorescence camera to have a 20 nanosecond delay in shooting relative to the gas phase fluorescence camera.

[0025] In addition, the present invention also provides a method for measuring the concentration of kerosene atomized gas-liquid two-phase mixture under coupled air intake conditions, comprising the following steps:

[0026] Step 100: Assemble the kerosene atomization gas-liquid two-phase concentration measurement system, and adjust the liquid phase fluorescence camera to delay the image capture of the spray section to be measured relative to the gas phase fluorescence camera;

[0027] Step 200: When the injection pressure of the injector drops to the set pressure, simultaneously acquire the original liquid phase fluorescence image and the original gas phase fluorescence image;

[0028] Step 300: Perform image processing on the original liquid phase fluorescence image and the original gas phase fluorescence image, and extract the contour information of the liquid phase fuel and the gas phase fuel.

[0029] Step 400: Calculate the fluorescence intensity of each pixel within the contour information of the liquid fuel and gas fuel, and obtain the gas-liquid two-phase concentration distribution of the spray section to be tested based on the relationship between fluorescence intensity and fuel vapor concentration in the gas phase and droplet liquid phase.

[0030] As a preferred embodiment of the present invention, the method for image processing of the original liquid-phase fluorescence image and the original gas-phase fluorescence image in step 300 is as follows:

[0031] The background of the original liquid phase fluorescence image and the original gas phase fluorescence image is subtracted to remove background noise when there is no spray;

[0032] Geometric correction and filtering are performed on the original liquid-phase fluorescence image and the original gas-phase fluorescence image after removing background noise to correct camera field-of-view distortion, and noise reduction processing is performed on the image to obtain the denoised liquid-phase fluorescence image and the denoised gas-phase fluorescence image.

[0033] The threshold is automatically determined by the maximum inter-class variance method to separate the spray area from the background in liquid phase fluorescence denoising images and gas phase fluorescence denoising images;

[0034] The contour information of liquid fuel and gaseous fuel is extracted using an edge detection algorithm.

[0035] The fluorescence intensity of each pixel in the contour information of liquid fuel and gas fuel is statistically analyzed. By analyzing the linear relationships between fluorescence intensity and fuel vapor concentration, as well as between fluorescence intensity and droplet concentration, the gas-liquid two-phase concentration distribution of the spray section under test is obtained.

[0036] As a preferred embodiment of the present invention, the linear relationship between gas phase fluorescence intensity and gas phase fuel density is as follows:

[0037] I v (i, j) = K v (i, j)×ρ v (i, j);

[0038] Among them, I v (i,j) represents the original fluorescence intensity value measured by the gas phase fluorescence camera at pixel position (i,j);

[0039] ρ v (i, j) represents the local mass density of the gaseous fuel to be determined;

[0040] K v (i, j) are local calibration coefficients that reflect the fluorescence intensity produced per unit density. They are affected by the following factors: the spatial distribution of laser sheet light intensity; the spatial non-uniformity of camera quantum efficiency and optical transmittance; and the effect of local temperature / pressure on fluorescence quantum yield.

[0041] The calculation process is as follows: In a standard gas-phase calibration experiment using n-undecane vapor of known concentration, fluorescence images I are acquired. v cal (i,j);

[0042] Known calibration concentration ρ v cal ,but:

[0043] ;

[0044] In actual measurements, substitute the formula back into the equation:

[0045] .

[0046] As a preferred embodiment of the present invention, the liquid phase concentration is determined by the mass conservation inversion method, specifically as follows:

[0047] Constrained by the axisymmetry assumption and mass conservation, the instantaneous total injection mass m is measured by a high-precision flow meter. total ;

[0048] Integrating the gas phase image, combined with the known K v (i,j), calculate the total mass of vapor phase fuel. Where L is the sheet thickness, and the total mass of the liquid phase is obtained. ;

[0049] Extract the pixel region V_pixel occupied by the liquid phase from the liquid phase fluorescence image and convert it into spatial volume V; average liquid phase density ρ l =m liquid / V;

[0050] This average density is compared with the average fluorescence intensity of the liquid phase image I. l Correlation yields the proportionality coefficient K. l =I l / ρ l Ultimately, the liquid phase concentration for each pixel is ρ. l (i,j)=I l (i,j) / K l .

[0051] Compared with the prior art, the present invention has the following advantages:

[0052] This invention innovatively adopts a "spectral-temporal dual-dimensional separation" strategy, which can significantly reduce spectral crosstalk and achieve higher purity signal separation while ensuring sufficient signal strength. Attached Figure Description

[0053] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0054] Figure 1 This is a schematic diagram of the gas-liquid two-phase concentration measurement system according to an embodiment of the present invention;

[0055] Figure 2 A structural diagram taken by the image acquisition system of this embodiment of the invention;

[0056] In the picture:

[0057] 1. Injector; 2. Laser light source; 3. Dual-color mirror; 4. Optical path system; 5. Image acquisition system; 6. Timing controller; 7. Data processing system.

[0058] Gas phase laser source 21, liquid phase laser source 22;

[0059] First quartz cylindrical lens 41, second concave quartz lens 42, third quartz cylindrical lens 43;

[0060] Gas fluorescence camera 51, liquid fluorescence camera 52. Detailed Implementation

[0061] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0062] like Figure 1 As shown, the present invention provides a kerosene atomization gas-liquid two-phase concentration measurement system under coupled air intake state, including: an injector 1, a laser light source 2, an image acquisition system 5, a timing controller 6, and a data processing system 7.

[0063] A mixture of base fuel and fluorescent tracer is introduced into the inlet of injector 1. Under high pressure, the mixture forms a spray. In this embodiment, the spray section to be tested in injector 1 is illuminated by a laser, and gas phase fluorescence signal is captured by gas phase fluorescence camera 51 and liquid phase fluorescence signal is captured by liquid phase fluorescence camera 52. After processing the captured gas phase fluorescence image and liquid phase fluorescence image, the gas-liquid two-phase concentration distribution of the spray section to be tested can be identified, realizing high-precision, synchronous, and quantitative measurement of the gas-liquid two-phase concentration field.

[0064] The laser source 2 includes a gas phase laser source 21 and a liquid phase laser source 22. The direction of the laser is adjusted by a dichroic mirror 3, and the laser with the adjusted direction illuminates the spray section to be measured of the injector 1 through the optical path system 4.

[0065] Among them, the gas phase laser source 21 and the liquid phase laser source 22 are distributed in the vertical direction. The gas phase laser source 21 and the liquid phase laser source 22 are transmitted in the same horizontal direction through the dichroic mirror 3. The gas phase laser source 21 and the liquid phase laser source 22 are set on the side of the spray path to be tested formed by the mixture of base fuel and fluorescent tracer liquid. The dichroic mirror 3 reflects the gas phase laser and transmits the liquid phase laser.

[0066] The gas phase laser source 21 outputs 266nm laser light, and the liquid phase laser source 22 outputs 532nm laser light.

[0067] 266nm laser (gas phase excitation): used to selectively excite TMPD monomer molecules (free state in the gas phase). Because its absorption peak is located in the ultraviolet region (~260–280nm), the 266nm laser can efficiently excite gas phase TMPD to produce 300-400nm fluorescence.

[0068] 532nm laser (liquid phase excitation): used to excite the TMPD-Np charge transfer complex (which is stable only in the liquid phase). This complex has strong absorption in the visible light region (~500–550nm), and the 532nm laser can efficiently excite it to produce 410-490nm fluorescence.

[0069] Simultaneous pulse excitation of two lasers ensures that the gas and liquid phases are illuminated synchronously at the same time and in the same spatial location, providing a prerequisite for subsequent synchronous imaging.

[0070] The optical path system 4 includes a first quartz cylindrical lens 41 for receiving the laser source 2, and a second concave quartz lens 42 and a third quartz cylindrical lens 43 disposed between the first quartz cylindrical lens 41 and the fuel injector 1.

[0071] The lasers emitted by the gas phase laser source 21 and the liquid phase laser source 22 pass through the first quartz cylindrical lens 41, the second concave quartz lens 42 and the third quartz cylindrical lens 43 in sequence, forming a sheet-like laser below the nozzle of the injector 1 to illuminate the spray section to be measured of the injector 1.

[0072] It should be noted that the focal length of the first quartz cylindrical lens 41 is -30mm, and the focal length of the second concave quartz lens 42 is 100mm.

[0073] The image acquisition system 5 includes a gas phase fluorescence camera 51 and a liquid phase fluorescence camera 52. An opening is provided in the direction of the inlet of the fuel injector 1, and a dichroic mirror 3 is provided at the intersection of the gas phase fluorescence camera 51 and the liquid phase fluorescence camera 52, so that the gas phase fluorescence camera 51 can capture and acquire gas phase fluorescence signals, and the liquid phase fluorescence camera 52 can capture and acquire liquid phase fluorescence signals.

[0074] The gas phase fluorescence camera 51 and the liquid phase fluorescence camera 52 are non-coaxially distributed.

[0075] The gas fluorescence camera 51 is equipped with a 300nm-400nm bandpass filter and is used to capture the fluorescence of p-tetramethyl-p-phenylenediamine (TMPD) monomer.

[0076] The liquid fluorescence camera 52 is equipped with a 410nm-490nm bandpass filter and a superimposed 532nm notch filter. The liquid fluorescence camera 52 is used to capture the fluorescence of the p-tetramethyl-p-phenylenediamine TMPD-naphthalene Np complex and to filter out the 532nm laser. Images captured by the gas fluorescence camera 51 and the liquid fluorescence camera 52 are shown below. Figure 2 As shown in the figure, the liquid fuel is mainly concentrated in the near field of the nozzle and is distributed in a ring shape, while the gaseous fuel is widely distributed in the surrounding area of ​​the liquid core.

[0077] The timing controller 6 is communicatively connected to the image acquisition system 5 and the laser source 2. The timing controller 6 is used to control the triggering timing of the laser source 2 and the image acquisition system 5 so that the time points for receiving the liquid phase fluorescence signal and receiving the gas phase fluorescence signal have a relative delay signal, so as to separate the gas phase fluorescence signal and the liquid phase fluorescence signal.

[0078] The timing controller 6 simultaneously excites the gas phase laser source 21 and the liquid phase laser source 22 to form laser pulses, and the timing controller 6 adjusts the liquid phase fluorescence camera 52 to have a 20 nanosecond delay in image capture relative to the gas phase fluorescence camera 51.

[0079] The data processing system 7 processes the gas phase fluorescence raw image and liquid phase fluorescence raw image acquired by the image acquisition system 5, and counts the fluorescence intensity of each pixel in the spray area of ​​the gas phase fluorescence raw image and liquid phase fluorescence raw image. Based on the relationship between fluorescence intensity and fuel vapor concentration in the gas phase and liquid droplet phase, the gas-liquid two-phase concentration distribution of the spray section to be tested is obtained.

[0080] Since the TMPD-Np complex is almost non-existent in the gas phase, the 532nm laser does not produce effective fluorescence in the gas phase. In the liquid phase, TMPD mainly exists in the form of a complex with extremely low monomer concentration, and the monomer fluorescence excited at 266nm (300nm–400nm) is completely blocked by the filter of the liquid phase camera. In addition, the 20ns time delay further suppresses residual crosstalk, thereby achieving physical + optical + temporal triple isolation to ensure that each camera responds only to the target phase state.

[0081] In this embodiment, the base fuel is n-undecane C 11 H 24 The fluorescent tracers used are tetramethyl-p-phenylenediamine (TMPD) and naphthalene (Np), with the following composition: tetramethyl-p-phenylenediamine (TMPD): naphthalene (Np): n-undecane (C). 11 H 24 The ratio is 1:9:90.

[0082] The carbon chain length and boiling point of n-undecane are closer to the average composition of aviation kerosene, thus ensuring that the tracer mixture has better evaporation synchronization and physical property matching with real kerosene, reducing measurement errors introduced by differences in phase change behavior.

[0083] While ensuring sufficient fluorescence intensity, this embodiment reduces the self-quenching effect of tetramethyl-p-phenylenediamine TMPD molecules in the gas phase by lowering the absolute concentration of TMPD, which also helps to suppress the tailing intensity of liquid phase fluorescence in the gas phase band.

[0084] This implementation proposes a "spectral-temporal dual-dimensional synergistic separation" mechanism: In the spectral dimension, the main emission peaks of TMPD monomer and TMPD-Np complex are captured by precisely designed bandpass filters (300nm-400nm and 410nm-490nm + 532nm notch) respectively; In the temporal dimension, the fluorescence lifetime difference between the two is utilized (the lifetime of TMPD-Np complex is about a few nanoseconds, while that of TMPD monomer can reach tens of nanoseconds), and a 20ns delay is set to allow the liquid phase camera to avoid the initial strong fluorescence pulse of the liquid phase, while retaining the measurable gas phase signal.

[0085] Therefore, this embodiment utilizes the differences in emission spectral bands and fluorescence lifetimes of different tracer components to effectively decouple the gas-phase fluorescence signal TMPD monomer from the liquid-phase fluorescence signal TMPD-Np complex, avoiding crosstalk caused by spectral overlap or similar lifetimes in traditional one-dimensional methods.

[0086] In summary, this implementation method innovatively adopts a "spectral-temporal dual-dimensional separation" strategy, which can significantly reduce spectral crosstalk and achieve higher purity signal separation while ensuring sufficient signal strength.

[0087] The specific working principle by which this embodiment can achieve the above functions is as follows:

[0088] Spectral dimension separation: Gas phase fluorescence camera 51 and liquid phase fluorescence camera 52 receive signals in different wavelength bands. Gas phase fluorescence camera 51 is equipped with a 300nm-400nm bandpass filter, which is specifically used to capture the fluorescence of p-tetramethyl-p-phenylenediamine (TMPD) monomer. Liquid phase fluorescence camera 52 is equipped with a 410nm-490nm bandpass filter and a superimposed 532nm notch filter. The 410nm-490nm bandpass filter is used to capture the fluorescence of TMPD-Np complex, while the 532nm notch filter is used to completely filter out Rayleigh scattering and Mie scattering light from the 532nm laser. This is a key step in improving the signal-to-noise ratio.

[0089] The emission peaks of the TMPD monomer and the TMPD-Np complex overlap significantly, making it impossible to resolve the interference of components with similar lifetimes using only spectroscopy. In this embodiment, the gas phase fluorescence camera 51 is equipped with a 300nm-400nm bandpass filter, while the liquid phase fluorescence camera 52 is equipped with a 410nm-490nm bandpass filter. This allows for the retention of sufficient fluorescence signals, while also incorporating time gating, i.e., applying a delay of approximately 20 nanoseconds to the liquid phase fluorescence camera 52, to further eliminate the contamination of the liquid phase channel by short-lived gas phase signals.

[0090] Temporal separation: Since the fluorescence of TMPD monomers and TMPD-Np complexes have different fluorescence lifetimes, after laser pulse excitation, a delay of about 20 nanoseconds is applied to the liquid phase fluorescence camera 52 that receives the liquid phase fluorescence. Since the lifetime of TMPD-Np complex fluorescence is usually shorter than that of TMPD monomer fluorescence, this delay can effectively avoid the initial strong pulse period of liquid phase fluorescence, while the gas phase fluorescence signal is still at a detectable level.

[0091] This "time-gated" technology can further strip away a portion of the liquid-phase fluorescence tail that enters the gas phase channel from the time axis, significantly reducing spectral crosstalk and achieving higher purity signal separation while ensuring sufficient signal strength.

[0092] To suppress specular reflection interference caused by the swirling flow, the gas phase fluorescence camera 51 and the liquid phase fluorescence camera 52 are arranged in a non-coaxial configuration, such as being positioned at a 90-degree angle through optical windows on the side of the test section, thus minimizing direct reflected light from entering the lens. Simultaneously, background image subtraction and normalization are employed in image processing to eliminate the influence of uneven intensity distribution of the laser sheet light itself.

[0093] This implementation method achieves simultaneous improvement in signal-to-noise ratio and separation through a triple mechanism:

[0094] ① Tracer system optimization: By adopting appropriate TMPD, Np, C 11 H 24 The formulation ensures the formation of a stable TMPD-Np complex in the liquid phase (with the emission peak red-shifted to 410–490 nm) while controlling the TMPD concentration to avoid self-quenching in the gas phase, thereby maximizing the fluorescence signal intensity and spectral separation between the two phases.

[0095] ② Two-dimensional orthogonal separation: In the spectral dimension, the 300-400nm channel contains almost no liquid-phase complex emission, and the 410-490nm channel has almost no contribution from TMPD monomers; In the temporal dimension, the 20ns delay is located in the "window period" after the rapid decay of liquid-phase fluorescence and when gas-phase fluorescence is still in the plateau period, thus filtering out crosstalk components in a dual manner.

[0096] ③ The gas / liquid phase camera adopts a non-coaxial 90° arrangement + two-color mirror beam splitting, which effectively avoids specular reflection and Rayleigh / Mie scattering (especially the 532nm laser is completely filtered out by the notch filter in front of the liquid phase camera), further improving the signal-to-noise ratio.

[0097] In addition, the present invention also provides a method for measuring the concentration of kerosene atomized gas-liquid two-phase mixture under coupled air intake conditions, comprising the following steps:

[0098] Step 100: Assemble the kerosene atomization gas-liquid two-phase concentration measurement system and adjust the liquid phase fluorescence camera to delay the image capture of the spray section to be measured relative to the gas phase fluorescence camera;

[0099] Step 200: When the fuel injection pressure of the injector drops to the set pressure (e.g., 0.3 MPa), simultaneously acquire the original liquid phase fluorescence image and the original gas phase fluorescence image;

[0100] Step 300: Perform image processing on the original liquid phase fluorescence image and the original gas phase fluorescence image, and extract the contour information of the liquid phase fuel and the gas phase fuel.

[0101] Step 400: Calculate the fluorescence intensity of each pixel within the contour information of liquid fuel and gaseous fuel. Based on the relationship between fluorescence intensity and fuel vapor concentration in the gas phase and droplet liquid phase, obtain the gas-liquid two-phase concentration distribution of the spray section to be tested.

[0102] In step 300, the method for image processing of the original liquid-phase fluorescence image and the original gas-phase fluorescence image is as follows:

[0103] Background was removed from the original liquid phase fluorescence image and the original gas phase fluorescence image to remove background noise when there was no spray.

[0104] Geometric correction and filtering were performed on the original liquid-phase fluorescence image and gas-phase fluorescence image after removing background noise to correct camera field distortion, and noise reduction was performed on the image to obtain the denoised liquid-phase fluorescence image and the denoised gas-phase fluorescence image.

[0105] The threshold is automatically determined by the maximum inter-class variance method to separate the spray area from the background in liquid phase fluorescence denoising images and gas phase fluorescence denoising images;

[0106] The contour information of liquid fuel and gaseous fuel is extracted using an edge detection algorithm.

[0107] The fluorescence intensity of each pixel in the contour information of liquid fuel and gas fuel is statistically analyzed. By analyzing the linear relationships between fluorescence intensity and fuel vapor concentration, as well as between fluorescence intensity and droplet concentration, the gas-liquid two-phase concentration distribution of the spray section under test is obtained.

[0108] The gas phase concentration is calibrated by establishing a linear relationship between gas phase fluorescence intensity and gas phase fuel density. The specific method is as follows:

[0109] I v (i,j)=K v (i,j)×ρ v (i,j);

[0110] Among them, I v (i,j) represents the original fluorescence intensity value measured by the gas phase fluorescence camera at pixel position (i,j);

[0111] ρ v(i,j) represents the local mass density of the gaseous fuel to be determined;

[0112] K v (i,j) are local calibration coefficients that reflect the fluorescence intensity produced per unit density. They are affected by the following factors: the spatial distribution of laser sheet light intensity; the spatial non-uniformity of camera quantum efficiency and optical transmittance; and the effect of local temperature / pressure on fluorescence quantum yield.

[0113] The calculation process is as follows: In a standard gas-phase calibration experiment using n-undecane vapor of known concentration, fluorescence images I are acquired. v cal (i,j);

[0114] Known calibration concentration ρ v cal ,but:

[0115] ;

[0116] In actual measurements, substitute the formula back into the equation:

[0117] .

[0118] Specifically, the liquid phase concentration is calibrated using the mass conservation inversion method, and the specific method is as follows:

[0119] Constrained by the axisymmetry assumption and mass conservation, the instantaneous total injection mass m is measured by a high-precision flow meter. total ;

[0120] Integrating the gas phase image, combined with the known K v (i,j), calculate the total mass of vapor phase fuel. Where L is the sheet thickness, and the total mass of the liquid phase is obtained. ;

[0121] Extract the pixel region V_pixel occupied by the liquid phase from the liquid phase fluorescence image and convert it into spatial volume V; average liquid phase density ρ l =m liquid / V;

[0122] This average density is compared with the average fluorescence intensity of the liquid phase image I. l Correlation yields the proportionality coefficient K. l =I l / ρ l Ultimately, the liquid phase concentration for each pixel is ρ. l (i,j)=I l (i,j) / K l .

[0123] This embodiment, through image processing of the captured raw liquid-phase fluorescence images and raw gas-phase fluorescence images, reveals that the liquid-phase fuel is mainly concentrated in the near field of the nozzle, exhibiting a ring-like distribution, while the gas-phase fuel is widely distributed in the peripheral area of ​​the liquid-phase core. The quantitative data obtained by this method can be used for in-depth analysis of fuel atomization, evaporation, and fuel-air mixing processes, providing crucial data support for the design and optimization of the combustion chamber.

[0124] The above embodiments are merely exemplary embodiments of this application and are not intended to limit this application. The scope of protection of this application is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to this application within its substance and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of this application.

Claims

1. A kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake conditions, characterized in that, include: The injector (1) introduces a mixture of base fuel and fluorescent tracer liquid into the inlet of the injector (1); The laser source (2) includes a gas phase laser source (21) and a liquid phase laser source (22). The direction of the laser is adjusted by a dichroic mirror (3), and the laser with the adjusted direction illuminates the spray section of the injector (1) through the optical path system (4). The image acquisition system (5) includes a gas phase fluorescence camera (51) and a liquid phase fluorescence camera (52), with an opening facing the inlet direction of the fuel injector (1), and a dichroic mirror (3) is provided at the intersection of the gas phase fluorescence camera (51) and the liquid phase fluorescence camera (52) so that the gas phase fluorescence camera (51) can capture and acquire gas phase fluorescence signals, and the liquid phase fluorescence camera (52) can capture and acquire liquid phase fluorescence signals. The timing controller (6) is communicatively connected to the image acquisition system (5) and the laser source (2). The timing controller (6) is used to control the triggering timing of the laser source (2) and the image acquisition system (5) so that the time points for receiving the liquid fluorescence signal and receiving the gas fluorescence signal have a relative delay signal, so as to separate the gas fluorescence signal and the liquid fluorescence signal. The data processing system (7) is used to process the gas phase fluorescence original image and liquid phase fluorescence original image acquired by the image acquisition system (5), and to count the fluorescence intensity of each pixel in the spray area of ​​the gas phase fluorescence original image and liquid phase fluorescence original image. Based on the relationship between fluorescence intensity and fuel vapor concentration in the gas phase and liquid phase, the gas-liquid two-phase concentration distribution of the spray section to be tested is obtained.

2. The kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake state according to claim 1, characterized in that, The gas phase laser source (21) and the liquid phase laser source (22) are distributed in a vertical direction. The gas phase laser source (21) and the liquid phase laser source (22) are transmitted in the same horizontal direction through a dichroic mirror (3). The gas phase laser source (21) and the liquid phase laser source (22) are located on the side of the test spray path formed by the mixture of base fuel and fluorescent tracer liquid. The gas phase laser source (21) outputs 266nm laser light, and the liquid phase laser source (22) outputs 532nm laser light. The dichroic mirror (3) reflects the gas phase laser and transmits the liquid phase laser.

3. The kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake state according to claim 2, characterized in that, The optical path system (4) includes a first quartz cylindrical lens (41) for receiving the laser light source (2), and a second concave quartz lens (42) and a third quartz cylindrical lens (43) disposed between the first quartz cylindrical lens (41) and the fuel injector (1). The lasers emitted by the gas phase laser source (21) and the liquid phase laser source (22) pass through the first quartz cylindrical lens (41), the second concave quartz lens (42) and the third quartz cylindrical lens (43) in succession, forming a sheet-like laser below the nozzle of the injector (1) to illuminate the spray section to be measured of the injector (1).

4. The kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake state according to claim 1, characterized in that, The base fuel is n-undecane (C 11 H 24 The fluorescent tracers selected are tetramethyl-p-phenylenediamine (TMPD) and naphthalene (Np). p-Tetramethyl-p-phenylenediamine (TMPD): Naphthalene (Np): n-Undecane (C 11 H 24 The ratio is 1:9:

90.

5. The kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake state according to claim 4, characterized in that, The gas phase fluorescence camera (51) and the liquid phase fluorescence camera (52) are non-coaxially distributed; The gas fluorescence camera (51) is equipped with a 300nm-400nm bandpass filter and is used to capture the fluorescence of tetramethyl-p-phenylenediamine (TMPD) monomer. The liquid fluorescence camera (52) is equipped with a 410nm-490nm bandpass filter and a superimposed 532nm notch filter. The liquid fluorescence camera (52) is used to capture the fluorescence of the tetramethyl-p-phenylenediamine (TMPD)-naphthalene (Np) complex and filter out the 532nm laser.

6. A kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake state according to claim 5 or 1, characterized in that, The timing controller (6) simultaneously excites the gas phase laser source (21) and the liquid phase laser source (22) to form laser pulses, and the timing controller (6) controls the liquid phase fluorescence camera (52) to have a 20 nanosecond delay in shooting relative to the gas phase fluorescence camera (51).

7. A method for measuring the concentration of kerosene atomized gas-liquid two-phase mixture under coupled air intake conditions, characterized in that, A kerosene atomized gas-liquid two-phase concentration measurement system under coupled air intake state according to any one of claims 1-6 includes the following steps: Step 100: Assemble the kerosene atomization gas-liquid two-phase concentration measurement system, and adjust the liquid phase fluorescence camera to delay the image capture of the spray section to be measured relative to the gas phase fluorescence camera; Step 200: When the injection pressure of the injector drops to the set pressure, simultaneously acquire the original liquid phase fluorescence image and the original gas phase fluorescence image; Step 300: Perform image processing on the original liquid phase fluorescence image and the original gas phase fluorescence image, and extract the contour information of the liquid phase fuel and the gas phase fuel. Step 400: Calculate the fluorescence intensity of each pixel within the contour information of the liquid fuel and gas fuel, and obtain the gas-liquid two-phase concentration distribution of the spray section to be tested by establishing the linear relationship between fluorescence intensity and fuel vapor concentration in the gas phase, and fluorescence intensity and droplet concentration.

8. The method for measuring the concentration of kerosene atomized gas-liquid two-phase mixture under coupled air intake conditions according to claim 7, characterized in that, In step 300, the method for image processing of the original liquid-phase fluorescence image and the original gas-phase fluorescence image is as follows: The background of the original liquid phase fluorescence image and the original gas phase fluorescence image is subtracted to remove background noise when there is no spray; Geometric correction and filtering are performed on the original liquid-phase fluorescence image and the original gas-phase fluorescence image after removing background noise to correct camera field-of-view distortion, and noise reduction processing is performed on the image to obtain the denoised liquid-phase fluorescence image and the denoised gas-phase fluorescence image. The threshold is automatically determined by the maximum inter-class variance method to separate the spray area from the background in liquid phase fluorescence denoising images and gas phase fluorescence denoising images; The contour information of liquid fuel and gaseous fuel is extracted using an edge detection algorithm. The fluorescence intensity of each pixel in the contour information of liquid fuel and gaseous fuel is statistically analyzed. Based on the relationship between fluorescence intensity and fuel vapor concentration in the gas phase and liquid droplet phase, the gas-liquid two-phase concentration distribution of the spray section to be tested is obtained.

9. The method for measuring the concentration of kerosene atomized gas-liquid two-phase mixture under coupled air intake conditions according to claim 8, characterized in that, The linear relationship between gas phase fluorescence intensity and gas phase fuel density is as follows: I v (i,j)=K v (i,j)×ρ v (i,j); Among them, I v (i,j) represents the original fluorescence intensity value measured by the gas phase fluorescence camera at pixel position (i,j); ρ v (i, j) represents the local mass density of the gaseous fuel to be determined; K v (i, j) are local calibration coefficients that reflect the fluorescence intensity produced per unit density. They are affected by the following factors: the spatial distribution of laser sheet light intensity; the spatial non-uniformity of camera quantum efficiency and optical transmittance; and the effect of local temperature / pressure on fluorescence quantum yield. The calculation process is as follows: In a standard gas-phase calibration experiment using n-undecane vapor of known concentration, fluorescence images I are acquired. v cal (i,j); Known calibration concentration ρ v cal ,but: ； In actual measurements, substitute the formula back into the equation: 。 10. The method for measuring the concentration of kerosene atomized gas-liquid two-phase mixture under coupled air intake conditions according to claim 8, characterized in that, The concentration of the liquid phase is determined using the mass conservation inversion method, specifically as follows: Constrained by the axisymmetry assumption and mass conservation, the instantaneous total injection mass m is measured by a high-precision flow meter. total ; Integrating the gas phase image, combined with the known K v (i,j), calculate the total mass of vapor phase fuel. Where L is the sheet thickness, and the total mass of the liquid phase is obtained. ; Extract the pixel region V_pixel occupied by the liquid phase from the liquid phase fluorescence image and convert it into spatial volume V; average liquid phase density ρ l =m liquid / V; This average density is compared with the average fluorescence intensity of the liquid phase image I. l Correlation yields the proportionality coefficient K. l =I l / ρ l Ultimately, the liquid phase concentration for each pixel is ρ. l (i,j)=I l (i,j) / K l .

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