Engine plume characteristic signal testing device and method

Abstract

According to the engine plume characteristic signal testing device and method of the present invention, there are three working modes: radiation measurement, particle measurement, and synchronous measurement. Particle parameters such as plume particle size, concentration, composition, and source identification, as well as radiation parameters such as radiation temperature, emissivity, and radiation intensity, are obtained synchronously, and then the engine plume characteristic signal is evaluated. The testing device includes a laser light source unit, a light receiving unit, a photoelectric detection unit, and a characteristic signal testing and processing unit. The laser light source unit is located on one side of the engine plume and is used to generate incident lasers of different wavelengths. The light receiving unit is located on the other side of the engine plume and is used to filter, converge, and receive radiation light or transmitted laser. The photoelectric detection unit is used to detect the intensity of light of different wavelengths received and converged by the light receiving unit. The characteristic signal testing and processing unit is used to control the working mode of the laser light source unit, process, save, and display the engine plume characteristic signal parameters.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerospace, and relates to a test device and method for engine plume characteristic signals. Background Art

[0002] The exhaust plumes of aerospace engines such as aeroengines, rocket engines, ramjets, and new engines are usually combustion products discharged from the nozzle at supersonic speed. They will further diffuse and expand at the nozzle exit to form a glowing and heating plume flow field. Their interaction with the surrounding environment will form various effects such as smoke, radiation, and attenuation of detection or guidance signals. These effects are collectively referred to as the characteristic signals of the exhaust plume. To further improve the performance such as the safety of aircraft, spacecraft, and weapon systems, while pursuing high energy in engine development, attention is also paid to the need for the engine plume to have low characteristic signals. The low characteristic signals of the engine plume usually refer to the characteristics such as low ultraviolet, visible, and infrared radiation, and no visible smoke in the exhaust, so as to ensure that aircraft, spacecraft, and weapon systems have reliable stealth performance and reduce the interference and attenuation of smoke on their own guidance and communication signals. In addition, during ground tests and flight of the engine, due to harsh working conditions, key structural components such as engine turbine blades and disks will inevitably be damaged due to rubbing or coating peeling off. The plume characteristic signals can also provide support for the safety monitoring of the engine working state.

[0003] The test of engine plume characteristic signals mainly includes plume particle and radiation parameters. However, the particle size and concentration parameters of these plume particles have a large range, and the temperature is high, with a multiphase existence, a large range of radiation bands, and strong radiation intensity, which bring great challenges to the test of engine plume characteristic signals. At present, there is no effective online synchronous test method for engine plume particle and radiation parameters to comprehensively evaluate engine plume characteristic signals. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a test device and method for engine plume characteristic signals, which have three working modes: radiation measurement, particle measurement, and synchronous measurement. By measuring the radiation energy distribution in the ultraviolet, visible, and infrared bands of the plume, as well as the attenuation degree of different wavelength lasers after passing through the plume to be measured, an analysis algorithm for engine plume characteristic signals is established to synchronously obtain particle parameters such as plume particle size, concentration, component, and source identification, and radiation parameters such as radiation temperature, emissivity, and radiation intensity, so as to evaluate the engine plume characteristic signals.

[0005] The present invention provides a test device for engine plume characteristic signals, having the following characteristics: including a laser light source unit located on one side of the engine plume for generating incident lasers of different wavelengths; a light receiving unit located on the other side of the engine plume for filtering, converging and receiving radiation light or transmitted laser; a photoelectric detection unit connected to the light receiving unit through an optical fiber for detecting the intensities of lights of different wavelengths received and converged by the light receiving unit; and a characteristic signal test and processing unit for controlling the working mode of the laser light source unit. Among them, the characteristic signal test and processing unit is respectively communicatively connected to the laser light source unit and the photoelectric detection unit, and processes, stores and displays the engine plume characteristic signal parameters.

[0006] The present invention provides a test device for engine plume characteristic signals, which may also have the following characteristics: Among them, the laser light source unit includes a laser controller, multiple lasers, an optical fiber coupler, and a collimator. The characteristic signal test and processing unit controls the working mode of the laser controller, the laser wavelength and the laser output intensity parameters. The laser controller is controlled by the characteristic signal test and processing unit through a control signal cable to turn on and off two working modes, the laser wavelength and the laser output intensity parameters. The laser generated by the laser is output to the optical fiber coupler through the optical fiber. The optical fiber coupler receives the laser generated by the laser and couples the laser to the output optical fiber. The collimator outputs the laser to irradiate the measurement area.

[0007] In addition, the present invention provides a test device for engine plume characteristic signals, which may also have the following characteristics: Among them, the light receiving unit includes a filter attenuator and a light collecting optical fiber coupler. The filter attenuator has two working modes of filtering light and non-filtering light. The plume radiation light, the laser generated by the laser light source unit or the mixed light of both enters the optical fiber coupler after passing through the filter attenuator and then is output.

[0008] In addition, the present invention provides a test device for engine plume characteristic signals, which may also have the following characteristics: Among them, the photoelectric detection unit includes a collimator, multiple gratings, multiple photodetectors and a photoelectric detection processor; the collimator is connected to the optical fiber coupler through an optical fiber, and the collimated laser after collimating the laser output by the light receiving unit is irradiated on the grating. After receiving the collimated laser, the grating is divided into multiple beams of light according to the wavelength. Multiple photodetectors respectively receive the multiple beams of light and convert the optical signals into electrical signals and output them through a cable; the photoelectric detection processor collects the electrical signals output by the multiple photodetectors and converts the electrical signals into digital signals, obtains the intensities of lights of different wavelengths, and outputs them to the characteristic signal test and processing unit through a digital signal communication cable.

[0009] In addition, the present invention provides a test device for engine plume characteristic signals, which may further have the following characteristics: The characteristic signal test and processing unit is connected to the laser light source unit and is used to control the generation and shutdown, wavelength, and intensity of the incident laser. The characteristic signal test and processing unit is connected to the light receiving unit and is used to control the working mode of the light receiving unit. The characteristic signal test and processing unit is connected to the photoelectric detection unit and is used to obtain the plume radiation light intensity at different wavelengths, the transmitted laser intensity at different wavelengths, and the intensity of the mixed light of the radiation light and the transmitted laser at different wavelengths. Based on the established analysis algorithm for engine plume characteristic signals, the plume particle and radiation parameters are obtained synchronously.

[0010] In addition, the present invention provides a test device for engine plume characteristic signals, which may further have the following characteristics: The light receiving unit includes a filter attenuator and a light collecting fiber optic coupler. The filter attenuator has two controllable working modes: with filtering and without filtering, and the attenuation degree is adjustable. It is controlled by the characteristic signal test and processing unit through a control signal cable. The plume radiation light, the laser generated by the laser light source unit, or the mixed light of both enters the fiber optic coupler after passing through the filter attenuator and is output by the optical fiber.

[0011] The photoelectric detection unit includes a collimator, multiple gratings, multiple photodetectors, and a photoelectric detection processor. The collimator is connected to the fiber optic coupler of the light receiving unit through an optical fiber, collimates the light obtained by the light receiving unit, and irradiates gratings in multiple different wavelength ranges in the ultraviolet, visible, and infrared bands. After receiving the light, the gratings are divided into multiple beams of spectral light according to the wavelength. There are two types of gratings: coarse gratings and fine gratings. Multiple photodetectors respectively receive the multiple beams of spectral light, convert the optical signals into electrical signals, and output them to the photoelectric detection processor through a cable. The photoelectric detection processor converts the electrical signals into digital signals, obtains the intensity of light at different wavelengths, and outputs them to the characteristic signal test and processing unit through a digital signal communication cable.

[0012] The characteristic signal test and processing unit controls the generation and shutdown, wavelength, and intensity of the incident laser by connecting to the laser controller through a control signal cable, controls the working modes of with filtering and without filtering by connecting to the filter attenuator through a control signal cable, and connects to the photoelectric detection processor through a digital signal communication cable to obtain the plume radiation light intensity at different wavelengths, the transmitted laser intensity at different wavelengths, and the intensity of the mixed light of the radiation light and the transmitted laser at different wavelengths in the ultraviolet, visible, and infrared bands. Based on the established analysis algorithm for engine plume characteristic signals, the plume particle and radiation parameters are obtained synchronously, and then the engine plume characteristic signals are evaluated.

[0013] A method for testing engine plume characteristic signals using the test device for engine plume characteristic signals according to any one of the above, characterized in that it includes the following test steps:

[0014] S1: Arrange the test device for engine plume characteristic signals;

[0015] S2: Determine the working mode of the engine plume characteristic signal test device, turn on the test device, record, process, and save the initial optical signal detected by the photoelectric detection unit before the test;

[0016] S3: Set the test timing according to the working mode of the engine plume characteristic signal test device and the test requirements, and conduct the plume characteristic signal test according to the timing, record, process, and save the optical signal detected by the photoelectric detection unit;

[0017] S4: Based on the established plume characteristic signal inversion algorithm, obtain the engine plume particle parameters and radiation parameters, and then evaluate the engine plume characteristic signal.

[0018] In addition, the engine plume characteristic signal test method provided by the present invention may also have the following characteristics: corresponding to the three working modes of radiation measurement, particle measurement, and synchronous measurement adopted by the engine plume characteristic signal test measurement device, there are also three methods for the engine plume characteristic signal test method:

[0019] Corresponding to the radiation measurement working mode adopted by the engine plume characteristic signal test measurement device, the engine plume characteristic signal test method uses the intensity data of plume radiation light with different wavelengths in the ultraviolet, visible, and infrared bands obtained by the photoelectric detection unit. The data has two characteristics: the continuous characteristic of plume radiation and the spectral line of particle radiation. The two characteristics are separated: the spectral line wavelength and spectral line intensity parameters are obtained according to the spectral line of particle radiation, the particle composition and concentration are determined by the particle composition inversion algorithm, and the particle source is analyzed and obtained through the particle source identification algorithm according to the spectral line wavelength, spectral line intensity, particle composition, and concentration information of the radiation characteristic spectral line; according to the continuous characteristic of plume radiation, the radiation parameters such as plume radiation temperature, emissivity, and radiation intensity are obtained through the radiation parameter inversion algorithm such as plume radiation temperature, emissivity, and radiation intensity; and then the engine plume characteristic signal is evaluated.

[0020] Corresponding to the particle measurement working mode adopted by the engine plume characteristic signal test measurement device, the engine plume characteristic signal test method uses the intensity data of transmitted laser light with different wavelengths that filters the plume radiation light obtained by the photoelectric detection unit. The data includes: the initial optical signal detected by the photoelectric detection unit before the test; the optical signal detected by the photoelectric detection unit during the test, that is, the intensity of the transmitted laser light with different wavelengths. For multiple lasers in the laser light source unit, there are multiple signal peaks, so as to obtain the transmitted laser light intensity I with different wavelengths and the initial light intensity I0. Through the particle size and concentration parameter synchronous inversion algorithm, the plume particle size and concentration parameters are synchronously obtained, and then the engine plume characteristic signal is evaluated.

[0021] For the synchronous measurement working mode adopted by the test and measurement device for the engine plume characteristic signals, the test method for the engine plume characteristic signals uses the intensity data of the mixed light of the radiation light with different wavelengths and the transmitted laser obtained by the optoelectronic detection unit. The data includes: the initial light signal detected by the optoelectronic detection unit before the test; the light signal detected by the optoelectronic detection unit during the test, that is, the intensity of the mixed light of the radiation light with different wavelengths and the transmitted laser, which has three characteristics: the continuous characteristic of plume radiation, the characteristic spectrum line of particulate radiation, and the transmitted laser. The spectral line wavelength and spectral line intensity parameters are obtained from the characteristic spectrum line of particulate radiation, the particulate components and concentration are determined through the particulate component inversion algorithm, and the particulate source is analyzed through the particulate source identification algorithm based on the information of the radiation characteristic spectrum line wavelength, spectral line intensity, particulate components and concentration; according to the continuous characteristic of plume radiation, the radiation parameters such as plume radiation temperature, emissivity, and radiation intensity are obtained through the radiation parameter inversion algorithms such as plume radiation temperature, emissivity, and radiation intensity; according to the characteristic of the transmitted laser, which is the transmitted laser caused by multiple lasers of the laser light source unit, the superimposed light intensity I' of the mixed light corresponding to different wavelengths can be obtained. It is necessary to subtract the radiation light intensity in the mixed light to obtain the accurate transmitted laser light intensity I:

[0022] I = I' - I r

[0023] I' is the light intensity corresponding to the wavelength obtained by the optoelectronic detection unit in the test measurement, and I r The radiation reference light intensity is obtained by interpolating the intensity data of the radiation light with the surrounding wavelengths, and then combined with the initial light intensity I0, the plume particulate size and concentration parameters are obtained through the synchronous inversion algorithm of particulate size and concentration parameters. Thus, the particulate parameters such as plume particulate size, concentration, components, and source identification and the radiation parameters such as radiation temperature, emissivity, and radiation intensity are obtained synchronously, and then the engine plume characteristic signals are evaluated.

[0024] In addition, the test method for the engine plume characteristic signals provided by the present invention may further have the following characteristics: the synchronous inversion algorithm of particulate size and concentration parameters is based on the attenuation degree of lasers with different wavelengths after passing through the plume to be measured conforming to the Beer-Lambert law. The relationship between the attenuation degrees of lasers with different wavelengths after passing through the plume to be measured is as follows:

[0025]

[0026] The subscript λ i represents different wavelengths; T is the transmittance, which is the ratio of the transmitted light intensity I to the initial light intensity I0; Q ext is a proportional constant related to the laser wavelength, particulate parameters, etc.; L is the plume thickness; N D is the particulate concentration, and f(D) is the particulate size distribution function. Thus, the plume transmittance T is obtained by experimentally measuring the transmitted light intensity I of lasers with different wavelengths and the initial light intensity I0.

[0027] Therefore, a system of linear equations can be obtained by experimentally measuring the attenuation of lasers with different wavelengths after passing through the plume to be measured:

[0028] E = Af

[0029] Each element in the extinction coefficient matrix A can be expressed as A ij = -3LN D c j Q ext (λ i , m, D) / 2D j , (i = 1, 2, … S; j = 1, 2, …, N), where N is the number of particle size bins, and c j is the numerical integration coefficient. f = [f(D1), f(D2), …, f(D j )] T is the particle size distribution function of the particle system to be measured, which is obtained by solving the system of linear equations. On this basis, the concentration of the particles to be measured can be obtained through the Beer-Lambert law.

[0030] In addition, the method for testing the characteristic signal of the engine plume provided by the present invention may further have the following characteristics: The particle component inversion algorithm is based on the fact that the particles in the high-temperature engine plume emit characteristic spectral lines in the ultraviolet, visible, or infrared wavelength bands with sufficient intensity, and the particle components are determined through the characteristic spectral lines.

[0031] The outer electrons of the atoms of the particles in the plume are in the ground state under normal conditions. When excited by the high-temperature environment, the excited atoms are in a very unstable state, and the outer electrons will spontaneously jump from a high energy level to a low energy level, releasing photons at the same time. The spontaneous emission frequency ν of the atoms is related to the energy level difference (E1 - E2) and satisfies:

[0032] hν = E1 - E2

[0033] h is Planck's constant.

[0034] When the system is in a thermal equilibrium state, the distribution of atoms among different energy stationary states follows the Boltzmann distribution:

[0035]

[0036] N n and N1 are the numbers of atoms in the excited state and the ground state respectively, and g n and g1 are the numbers and statistical weights of atoms in the excited state and the ground state respectively, E 1n is the excitation energy required from the ground state to the excited state, k is the Boltzmann constant, and T is the temperature at which the atoms are located. Thus, the particle components can be determined and the component concentrations can be obtained through the analysis of the wavelength and intensity of the characteristic spectral lines.

[0037] In addition, the engine plume characteristic signal testing method provided by the present invention may further have the following feature: the particle source identification algorithm is mainly obtained based on the K-means clustering algorithm for plume radiation spectrum clustering analysis.

[0038] The basic idea of K-means clustering is to randomly select k data samples from a dataset containing a large number of radiation spectrum samples of solid particles as the initial clustering centers, calculate the distances between each spectrum sample and the k initial clustering centers, divide all spectrum data into the categories represented by the clustering centers with the closest distances, and update the k clustering centers according to the means of the spectrum samples in each newly generated category. If the change in the clustering center values within adjacent iteration times exceeds the set threshold, then all spectrum samples are re-classified based on the new clustering centers; if the change in the clustering center values within adjacent iteration times is less than the specified threshold, the algorithm converges and the clustering result is output.

[0039] The process of the K-means clustering algorithm is as follows:

[0040] (a) Select the original dataset for K-means clustering, and randomly select k spectrum samples from it as the initial clustering centers z1, z2, …, z k ;

[0041] (b) Calculate the distances from all spectrum sample data to the k condensation points one by one (usually using the Euclidean distance as the distance from the sample to the clustering center), and divide the n samples (or variables) into k categories according to the distances. The Euclidean distance calculation formula is as follows:

[0042]

[0043] x i is the value of the i-th variable of sample x, and y i is the value of the i-th variable of sample y. If the spectrum sample is closest to the distance of its original class, it remains in the original class; otherwise, it is moved to the class with the closest distance to it;

[0044] (c) Calculate the clustering centers of each of the k categories of data. If the clustering center does not coincide with the initial clustering center, then use this clustering center as the new clustering center and repeat step (b) until all spectrum samples cannot be moved, or until each clustering center no longer changes, then the calculation process terminates, thereby identifying the source of the engine plume particles.

[0045] Through a large number of plume radiation spectrum clustering analyses, specific wavelength characteristics for particle source identification can be obtained, so that it is not necessary to obtain the radiation light wavelength intensity data of all bands, only the data of several determined wavelengths are required, and the testing device and the particle source identification algorithm can be further simplified.

[0046] In addition, the engine plume characteristic signal testing method provided by the present invention may further have the following feature: the radiation parameter inversion algorithms such as plume radiation temperature, emissivity, and radiation intensity are established based on the Planck radiation law parameter fitting method.

[0047] The measured radiation intensities of the plume at different wavelengths are:

[0048]

[0049] ε is the average emissivity of the plume, and its value is a constant between 0 and 1; T is the average thermodynamic temperature of the field of view, and k is the correction coefficient for detection response at different wavelengths, which is related to the optoelectronic detection response, optical fiber transmission, and relevant parameters of the test system.

[0050] According to the measurement conditions and calculation range, when λT << 2000μmT, the Planck radiation law can be simplified to the Wien relation:

[0051]

[0052] Taking the logarithm of both sides of the above equation, letting ε’ = lnε, t = 1 / T, and substituting ε’ and t into the above equation, we can get:

[0053]

[0054] Establish a multivariate function f(ε’, t) and use the polynomial y i for curve fitting:

[0055]

[0056] y i is the logarithm of the radiation intensity at the wavelength of λ i obtained from experimental measurement. According to the least squares method, when the sum of the squares of the deviations in the above equation is minimized, the corresponding values of ε’ and t are calculated, and substituting them back into the formulas ε’ = lnε and t = 1 / T, the average temperature and emissivity parameters obtained from experimental measurement can be obtained.

[0057] On the basis of obtaining the plume radiation temperature and emissivity parameters here, according to the Planck law, the plume radiation intensities at different wavelengths in the entire wavelength range such as ultraviolet, visible, and infrared bands can be calculated, and the total radiation intensity can be obtained through integration over the entire wavelength range.

[0058] The present invention provides an engine plume characteristic signal testing method, which has the following feature: the engine plume characteristic signal testing device has three working modes: radiation measurement, particle measurement, and synchronous measurement.

[0059] In the radiation measurement working mode of the engine plume characteristic signal test device, the laser light source part adopts a closed working mode, and the light receiving part adopts a non-filtering working mode. The light receiving part is used to converge and obtain the plume radiation light. Correspondingly, the photoelectric detection part directly detects the intensities of plume radiation lights with different wavelengths in the ultraviolet, visible, and infrared bands to obtain radiation parameters such as plume radiation temperature, emissivity, and radiation intensity.

[0060] In the particle measurement working mode of the engine plume characteristic signal test device, the laser light source part adopts an open working mode, and the light receiving part adopts a filtering working mode. The light receiving part is used to filter the plume radiation light and converge the transmitted lasers with different wavelengths. Correspondingly, the photoelectric detection part detects the intensities of the transmitted lasers with different wavelengths after filtering the plume radiation light to obtain plume particle size and concentration parameters, and further evaluate the engine plume characteristic signal.

[0061] In the synchronous measurement working mode of the engine plume characteristic signal test device, the laser light source part adopts an open working mode, and the light receiving part adopts a non-filtering working mode. The light receiving part is used to converge and obtain the mixed light of plume radiation light and transmitted laser. Correspondingly, the photoelectric detection part detects the intensities of the mixed light of radiation lights and transmitted lasers with different wavelengths to synchronously obtain particle parameters such as plume particle size, concentration, composition, and source identification, and radiation parameters such as radiation temperature, emissivity, and radiation intensity.

[0062] The present invention provides an engine plume characteristic signal test method, which has the following characteristics: the working mode of the engine plume characteristic signal test device should be determined according to the engine test requirements and the types of parameters that can be obtained according to the above working modes, and correspondingly determine the working modes of the laser light source part and the light receiving part.

[0063] The selection of the laser wavelengths of multiple lasers in the laser light source part and the filtering wavelength range of the filtering attenuator in the light receiving part is usually in the blue-violet light band to eliminate the influence of plume radiation light.

[0064] The selection of the intensities of multiple lasers, the attenuation rate of the filtering attenuator, and the beam cross-sectional diameter of the laser needs to ensure that the attenuation degree of the transmitted laser is in the range of 10-90%. This is related to the attenuation degree caused by the plume particle size and concentration. The stronger the attenuation, the higher the laser intensity, the smaller the attenuation rate of the filtering attenuator, and the larger the beam cross-sectional diameter. Among them, the beam cross-sectional diameter of the laser is adjusted through the collimator in the laser light source part and the area parameter of the filtering attenuator in the light receiving part.

[0065] The selection of the data wavelengths of the photoelectric detection part is determined by analyzing the wavelengths of the data in combination with the test requirements.

[0066] The grating of the photoelectric detection unit can be one, two or more. The number of gratings, the working wavelength band, as well as the number and working wavelength band of the corresponding multiple photodetectors are determined according to the optical wavelength range obtained by the receiving unit, the wavelength range of the data to be analyzed for testing, and the characteristics of the grating working wavelength band.

[0067] The present invention provides an engine plume characteristic signal testing device, which has the following characteristics: The particles in the plume tested by the engine plume characteristic signal testing device can be the particles generated by the combustion of engine fuel, or the particles inevitably generated by the abrasion or coating shedding of key structural components such as engine turbine blades and disks due to harsh working conditions during ground tests and flight of the engine.

[0068] The present invention provides an engine plume characteristic signal testing device for measuring the radiation energy distribution of the engine plume and the attenuation degree of different wavelength lasers after passing through the plume to be tested. It is characterized by including: a flue, arranged outside the engine and the engine plume, for collecting the smoke generated during the engine test. Two optical windows are symmetrically arranged on the flue. A laser light source unit, located on one side of an optical window, for generating incident lasers of different wavelengths; a light receiving unit, located on the other side of the optical window, for filtering, converging and receiving radiation light or transmitted laser; a photoelectric detection unit, connected to the light receiving unit through an optical fiber, for detecting the intensity of light of different wavelengths received and converged by the light receiving unit; and a characteristic signal testing and processing unit, for controlling the working mode of the laser light source unit. Among them, the characteristic signal testing and processing unit is respectively communicatively connected to the laser light source unit and the photoelectric detection unit, and processes, stores and displays the engine plume characteristic signal parameters.

[0069] Functions and effects of the invention

[0070] The engine plume characteristic signal testing device and method involved in the present invention have the following functions and effects:

[0071] (1) By measuring the radiation energy distribution in the ultraviolet, visible and infrared wavelength bands of the plume, as well as the attenuation degree of different wavelength lasers after passing through the plume to be tested, the present invention establishes an engine plume characteristic signal analysis algorithm, and synchronously obtains particle parameters such as particle size, concentration, composition and source identification of the plume, and radiation parameters such as radiation temperature, emissivity and radiation intensity, so as to evaluate the engine plume characteristic signal, without the need for multiple testing devices to obtain the engine plume characteristic signals at different wavelengths, further simplifying the engine plume characteristic signal testing device and method.

[0072] (2) The present invention has various layout forms such as direct plume testing and flue testing. By controlling the working modes of the laser light source part and the light receiving part, three working modes of radiation measurement, particle measurement, and synchronous measurement are formed, which can very conveniently meet the synchronous testing of particle parameters such as plume particle size, concentration, composition, source identification, etc. and radiation parameters such as radiation temperature, emissivity, and radiation intensity under different testing requirements, and then evaluate the engine plume characteristic signals.

[0073] (3) When the synchronous measurement working mode is adopted in the present invention, the intensity data of the mixed light of the radiation light and the transmitted laser at different wavelengths are detected. Through data conversion, the accurate light intensity data of the transmitted laser in the mixed light can be obtained, so as to realize the synchronous testing of particle parameters such as plume particle size, concentration, composition, source identification, etc. and radiation parameters such as radiation temperature, emissivity, and radiation intensity.

[0074] (4) The selection of the laser wavelength, intensity, working mode of multiple lasers in the laser light source part of the present invention, the filtering wavelength range, attenuation rate, working mode of the filter attenuator in the light receiving part, and the data wavelength of the photoelectric detection part, etc. need to be determined in combination with parameters such as the engine plume particle size parameter range, particle concentration parameter concentration, and plume radiation spectrum. The laser wavelength is usually selected as blue-violet light, which can ensure that the laser light intensity measurement is not affected by the radiation light and improve the test accuracy of particle size and concentration parameters. Description of the Drawings

[0075] Figure 1 It is a schematic diagram of the direct plume testing layout form of the engine plume characteristic signal testing device in the embodiment;

[0076] Figure 2 It is a schematic diagram of the flue testing layout form of the engine plume characteristic signal testing device in the embodiment;

[0077] Figure 3 It is a schematic diagram of the typical data processing of the three working modes of the engine plume characteristic signal in the embodiment;

[0078] Figure 4 It is a schematic diagram of the principle of the particle size and concentration parameter testing in the engine plume characteristic signal testing method in the embodiment. Detailed Embodiment

[0079] In order to make the technical means, creative features, achieved purposes, and effects of the present invention easy to understand, the following embodiments will specifically describe the engine plume characteristic signal testing device and method of the present invention in combination with the drawings.

[0080] The engine plume characteristic signal testing device provided in the embodiment has three working modes: radiation measurement, particle measurement, and synchronous measurement. By measuring the radiation energy distribution in the ultraviolet, visible, and infrared bands of the plume, as well as the attenuation degree of lasers with different wavelengths after passing through the plume to be measured, an analysis algorithm for engine plume characteristic signals is established. Particle parameters such as plume particle size, concentration, composition, and source identification, and radiation parameters such as radiation temperature, emissivity, and radiation intensity are obtained synchronously, and then the engine plume characteristic signals are evaluated. The working timing of the testing device is synchronized with the engine test according to the engine test requirements, or is tested within a certain time after the engine test ends. It can be used for testing the characteristic signals of the exhaust plume or tail jet of aeroengines, rocket engines, ramjets, and new engines, etc. There are two implementation methods: direct plume testing and flue testing layout.

[0081] Embodiment 1

[0082] As Figure 1 shown, this embodiment provides an engine plume characteristic signal testing device, including: a laser light source unit 2, a light receiving unit 3, a photoelectric detection unit 4, a characteristic signal testing and processing unit 5, cables 25, 51, 52, 53, 433, 443, and optical fibers 26, 28, 30.

[0083] The laser light source unit 2 and the light receiving unit 3 of the testing device are correspondingly arranged on both sides of the area to be measured 13 of the engine plume 12 near the outlet of the engine 11.

[0084] Among them, the laser light source unit 2 is located on one side of the engine plume 12 and is used to generate incident lasers 20 with different wavelengths.

[0085] The light receiving unit 3 is located on the other side of the engine plume 12 and is used to converge and receive the transmitted laser and the plume 12 radiation light after passing through the plume to be measured.

[0086] The photoelectric detection unit 4 is respectively connected to the characteristic signal testing and processing unit 5 and the light receiving unit 3, and is used to detect the intensity of light with different wavelengths received and converged by the light receiving unit 3.

[0087] The characteristic signal testing and processing unit 5 is respectively connected to the light receiving unit 3 and the photoelectric detection unit 4, and is used to control the laser light source unit 2.

[0088] The laser light source unit 2 includes a laser controller 21, multiple lasers 22, 23, 24, an optical fiber coupler 27, and a collimator 29.

[0089] The characteristic signal testing and processing unit 5 controls the working mode of the laser controller 21, the wavelengths of the lasers 22, 23, 24, and the laser output intensity parameters through the control signal cable 71. The laser controller 21 has two working modes: on and off.

[0090] Among them, the laser controller 21 is connected in parallel with the lasers 22, 23, and 24 through cables 25 respectively, and is used to control the lasers 22, 23, and 24 with different wavelengths to generate laser light.

[0091] The laser light generated by the lasers 22, 23, and 24 is output to the fiber optic coupler 27 through the optical fiber 26. The fiber optic coupler 27 receives the laser light generated by the lasers 22, 23, and 24, couples the laser light into the output optical fiber 28, and is connected to the collimator 29. The collimator 29 outputs the laser light 20 to irradiate the measurement area 13.

[0092] The light receiving part 3 includes a filter attenuator 31 and a light collecting fiber optic coupler 32.

[0093] The filter attenuator 31 has two controllable operating modes: with filter and without filter, and the attenuation degree is adjustable, which is controlled by the characteristic signal test and processing part 5 through the control signal cable 52.

[0094] The radiation light of the plume 12, the laser light generated by the laser light source part 2, or the mixed light of both enters the fiber optic coupler 32 after passing through the filter attenuator 31 and is output through the optical fiber 30.

[0095] The photoelectric detection part 4 includes a collimator 41, a plurality of gratings 42, 43, 44, a plurality of photodetectors 432, 442, and a photoelectric detection processor 45.

[0096] The collimator 41 is connected to the fiber optic coupler 32 of the light receiving part 3 through the optical fiber 30, collimates the light obtained by the light receiving part 3, and irradiates the gratings 42, 43, 44 with multiple different wavelength ranges in the ultraviolet, visible, and infrared bands. After receiving the light, the gratings 42, 43, 44 divide the light into multiple beams of spectral light 431, 441 according to the wavelength. There are two types of gratings: a coarse grating 42 and fine gratings 43, 44. After the plurality of photodetectors 432, 442 receive the multiple beams of spectral light 431, 441 respectively, they convert the optical signals into electrical signals and output them to the photoelectric detection processor 45 through the cables 433, 443. The photoelectric detection processor 45 converts the electrical signals into digital signals, obtains the intensities of light with different wavelengths, and outputs them to the characteristic signal test and processing part 5 through the digital signal communication cable 53.

[0097] The characteristic signal test and processing part 5 controls the generation and shutdown, wavelength, and intensity of the incident laser through the control signal cable 51 connected to the laser controller 21, controls the operating modes of with filter and without filter through the control signal cable 52 connected to the filter attenuator 31, and obtains the intensities of plume radiation light with different wavelengths, transmitted laser light with different wavelengths, and mixed light of radiation light and transmitted laser light with different wavelengths in the ultraviolet, visible, and infrared bands through the digital signal communication cable 53 connected to the photoelectric detection processor 45. Based on the established analysis algorithm for engine plume characteristic signals, the plume particle and radiation parameters are obtained synchronously, and then the characteristic signals of the engine plume 12 are evaluated.

[0098] In the radiation measurement working mode of the engine plume characteristic signal test device, the laser light source unit 2 adopts a closed working mode, and the light receiving unit 3 adopts a non-filtering working mode. The light receiving unit 3 is used to converge and obtain the plume radiation light. Correspondingly, the photoelectric detection unit 4 directly detects the intensities of plume radiation lights with different wavelengths in the ultraviolet, visible, and infrared bands to obtain radiation parameters such as plume radiation temperature, emissivity, and radiation intensity.

[0099] Furthermore, in the particle measurement working mode of the engine plume characteristic signal test device, the laser light source unit 2 adopts an on working mode, and the light receiving unit 3 adopts a filtering working mode. The light receiving unit 3 is used to filter the plume radiation light and converge the transmitted lasers with different wavelengths. Correspondingly, the photoelectric detection unit 4 detects the intensities of the transmitted lasers with different wavelengths after filtering the plume radiation light to obtain plume particle size and concentration parameters, and further evaluate the engine plume characteristic signal.

[0100] Furthermore, in the synchronous measurement working mode of the engine plume characteristic signal test device, the laser light source unit 2 adopts an on working mode, and the light receiving unit 3 adopts a non-filtering working mode. The light receiving unit 3 is used to converge and obtain the mixed light of plume radiation light and transmitted laser. Correspondingly, the photoelectric detection unit 4 detects the intensities of the mixed light of radiation lights and transmitted lasers with different wavelengths to synchronously obtain particle parameters such as plume particle size, concentration, composition, and source identification, and radiation parameters such as radiation temperature, emissivity, and radiation intensity.

[0101] Furthermore, the working mode of the test device should be determined according to the engine test requirements and the types of parameters that can be obtained according to the above working modes, and correspondingly determine the working modes of the laser light source unit and the light receiving unit.

[0102] The selection of the laser wavelengths of the multiple lasers 22, 23, 24 in the laser light source unit 2 and the filtering wavelength range of the filtering attenuator 31 in the light receiving unit 3 is usually in the blue-violet light band to eliminate the influence of the plume radiation light.

[0103] The selection of the intensities of the multiple lasers, the attenuation rate of the filtering attenuator, and the beam cross-sectional diameter of the laser 20 needs to ensure that the attenuation degree of the transmitted laser is in the range of 10-90%. This is related to the attenuation degree caused by the plume particle size and concentration. The stronger the attenuation, the higher the laser intensity, the lower the attenuation rate of the filtering attenuator, and the larger the beam cross-sectional diameter. Among them, the beam cross-sectional diameter of the laser 20 is adjusted through the area parameters of the collimator 29 in the laser light source unit 2 and the filtering attenuator 31 in the light receiving unit 3.

[0104] The selection of the data wavelengths of the photoelectric detection unit 4 is determined by analyzing the wavelengths of the data in combination with the test requirements.

[0105] The gratings 42, 43, 44 of the photoelectric detection unit 4 can be one, two or more. The number of gratings, the working wavelength band, as well as the number and working wavelength band of the corresponding multiple photodetectors 432, 442 are determined according to the optical wavelength range obtained by the receiving unit, the wavelength range of the data to be analyzed for testing, and the characteristics of the grating working wavelength band.

[0106] Furthermore, the particles in the plume can be the particles generated by the fuel combustion of the engine 11, or the particles inevitably generated due to the abrasion or coating peeling of the key structural components such as the turbine blades and disks of the engine during ground tests and flight due to harsh working conditions.

[0107] This embodiment also provides a method for testing the engine plume characteristic signal. The testing steps include:

[0108] S1: Arrange the engine plume characteristic signal testing device;

[0109] S2: Determine the working mode of the engine plume characteristic signal testing device, turn on the testing device, and record, process, and save the initial optical signal detected by the photoelectric detection unit before the test;

[0110] S3: According to the working mode of the engine plume characteristic signal testing device and the testing requirements, set the test timing sequence, and conduct the plume characteristic signal test according to the timing sequence, record, process, and save the optical signal detected by the photoelectric detection unit;

[0111] S4: Based on the established plume characteristic signal inversion algorithm, obtain the engine plume particle parameters and radiation parameters, and then evaluate the engine plume characteristic signal.

[0112] Furthermore, in the method for testing the engine plume characteristic signal provided by this embodiment, corresponding to the radiation measurement working mode adopted by the engine plume characteristic signal test measurement device, the method for testing the engine plume characteristic signal uses the plume radiation light intensity data of different wavelengths in the ultraviolet, visible, and infrared wavelength bands obtained by the photoelectric detection unit 4, as Figure 3 shown in (a). The data curve has two characteristics: the continuous characteristic of plume radiation and the characteristic spectral line of particle radiation. The two characteristics are separated:

[0113] According to the characteristic spectral line of particle radiation, obtain the spectral line wavelength and spectral line intensity parameters, determine the particle composition and concentration through the particle composition inversion algorithm, and analyze the particle source through the particle source identification algorithm based on the information of the spectral line wavelength, spectral line intensity, particle composition, and concentration of the radiation characteristic spectral line;

[0114] According to the continuous characteristic of plume radiation, through the radiation parameter inversion algorithms such as plume radiation temperature, emissivity, and radiation intensity, obtain the radiation parameters such as plume radiation temperature, emissivity, and radiation intensity; and then evaluate the engine plume characteristic signal.

[0115] Furthermore, in the engine plume characteristic signal testing method provided in this embodiment, corresponding to the particle measurement working mode adopted by the engine plume characteristic signal test measurement device, the engine plume characteristic signal testing method uses the intensity data of the transmitted laser of different wavelengths filtering the plume radiation light obtained by the photoelectric detection unit 4. For example, Figure 3 (b) shows that the solid line is the initial light signal detected by the photoelectric detection unit 4 before the test, and the dashed line is the light signal detected by the photoelectric detection unit 4 during the test, which is the intensity of the transmitted laser of different wavelengths. For the multiple lasers of the laser light source unit 2, there are multiple signal peaks, so as to obtain different wavelengths λ i The transmitted laser light intensity I and the initial light intensity I0, through the above-mentioned synchronous inversion algorithm of particle size and concentration parameters, synchronously obtain the plume particle size and concentration parameters, and then evaluate the engine plume characteristic signal.

[0116] Furthermore, in the engine plume characteristic signal testing method provided in this embodiment, corresponding to the synchronous measurement working mode adopted by the engine plume characteristic signal test measurement device, the engine plume characteristic signal testing method uses the intensity data of the mixed light of the radiation light and the transmitted laser of different wavelengths obtained by the photoelectric detection unit 4. For example, Figure 3 (c) shows that the solid line is the initial light signal detected by the photoelectric detection unit 4 before the test, and the dashed line is the light signal detected by the photoelectric detection unit 4 during the test, which is the intensity of the mixed light of the radiation light and the transmitted laser of different wavelengths, having three characteristics: the continuous characteristic of plume radiation, the characteristic spectral line of particle radiation, and the transmitted laser. Figure 3 In (c), I’ is the light intensity of the corresponding wavelength obtained by the test and detection photoelectric detection unit, and I r The radiation reference light intensity obtained by interpolating the intensity data of the surrounding wavelength radiation light.

[0117] According to the characteristic spectral line of particle radiation, obtain the spectral line wavelength and spectral line intensity parameters, determine the particle components and concentration through the particle component inversion algorithm, and analyze the particle source through the particle source identification algorithm according to the radiation characteristic spectral line wavelength, spectral line intensity, particle components and concentration information.

[0118] According to the continuous characteristic of plume radiation, through the radiation parameter inversion algorithms such as plume radiation temperature, emissivity, and radiation intensity, obtain the radiation parameters such as plume radiation temperature, emissivity, and radiation intensity.

[0119] According to the characteristic of the transmitted laser, the transmitted laser caused by the multiple lasers of the laser light source unit 2, so that different wavelengths λ i The corresponding superimposed light intensity I’ of the mixed light is obtained. It is necessary to subtract the radiation light intensity in the mixed light to obtain the accurate transmitted laser light intensity I:

[0120] I = I’ - I r

[0121] I' is the light intensity corresponding to the wavelength obtained by the test of the optoelectronic detection unit, and I r The radiation reference light intensity is obtained by interpolating the intensity data of the light radiated by the surrounding wavelengths, and then combined with the initial light intensity I0. Through the above-mentioned synchronous inversion algorithm of particle size and concentration parameters, the particle size and concentration parameters of the plume particles are obtained.

[0122] Thus, the particle parameters such as the particle size, concentration, composition, and source identification of the plume particles and the radiation parameters such as the radiation temperature, emissivity, and radiation intensity are obtained synchronously, and then the characteristic signal of the engine plume is evaluated.

[0123] Furthermore, in the method for testing the characteristic signal of the engine plume provided in this embodiment, the above-mentioned synchronous inversion algorithm of particle size and concentration parameters is established based on the attenuation degree of different-wavelength lasers passing through the plume to be measured conforming to the Beer-Lambert law, such as Figure 4 As shown, the relationship between the attenuation degrees of different-wavelength lasers passing through the plume to be measured is as follows:

[0124]

[0125] The subscript λ i represents different wavelengths; T is the transmittance, which is the ratio of the transmitted light intensity I to the initial light intensity I0; Q ext is a proportionality constant, which is related to the laser wavelength, particle parameters, etc.; L is the plume thickness; N D is the particle concentration, and f(D) is the particle size distribution function. Thus, the plume transmittance T is obtained by experimentally measuring the transmitted light intensity I of different-wavelength lasers and the initial light intensity I0.

[0126] Therefore, a system of linear equations is obtained by experimentally measuring the attenuation of different-wavelength lasers passing through the plume to be measured:

[0127] E = Af

[0128] Each element in the extinction coefficient matrix A can be expressed as A ij =-3LN D c j Q ext (λ i ,m,D) / 2D j , (i = 1, 2,..., S; j = 1, 2,..., N), where N is the number of particle size bins, and c j is the numerical integration coefficient. f = [f(D1), f(D2),..., f(D j )] T is the particle size distribution function of the particle system to be measured, which is obtained by solving the system of linear equations. On this basis, the concentration of the particles to be measured is obtained through the Beer-Lambert law.

[0129] Further, in the engine plume characteristic signal testing method provided in this embodiment, the above-mentioned particle component inversion algorithm is based on the fact that particles in the high-temperature engine plume emit sufficiently strong radiation characteristic spectral lines in the ultraviolet, visible, or infrared bands, and the particle components are determined through the characteristic spectral lines.

[0130] The outer electrons of the atoms of the particles in the plume are in the ground state under normal conditions. When excited by the high-temperature environment outside, the excited atoms are in a very unstable state, and the outer electrons will spontaneously jump from the high energy level to the low energy level, while releasing photons. The spontaneous emission frequency ν of the atom is related to the energy level difference (E1 - E2) and satisfies:

[0131] hν = E1 - E2

[0132] h is Planck's constant.

[0133] When the system is in a thermal equilibrium state, the distribution of atoms among various energy stationary states follows the Boltzmann distribution:

[0134]

[0135] N n and N1 are the numbers of atoms in the excited state and the ground state respectively, g n and g1 are the numbers and statistical weights of atoms in the excited state and the ground state respectively, E 1n is the excitation energy required from the ground state to the excited state, k is the Boltzmann constant, and T is the temperature at which the atoms are located. Thus, the particle components can be determined and the component concentrations can be obtained through the analysis of the wavelength and intensity of the characteristic spectral lines.

[0136] Further, in the engine plume characteristic signal testing method provided in this embodiment, the above-mentioned particle source identification algorithm is mainly obtained based on the K-means clustering algorithm for plume radiation spectrum clustering analysis.

[0137] The basic idea of K-means clustering is to randomly select k data samples from a dataset containing a large number of radiation spectrum samples of solid particles as the initial clustering centers, calculate the distances between each spectrum sample and the k initial clustering centers, divide all spectral data into the categories represented by the clustering centers with the closest distances to them, and update the k clustering centers according to the means of the spectral samples in the newly generated categories. If the change in the clustering center values within adjacent iteration times exceeds the set threshold, then all spectral samples are re-classified according to the new clustering centers; if the change in the clustering center values within adjacent iteration times is less than the specified threshold, the algorithm converges and the clustering result is output.

[0138] The process of the K-means clustering algorithm is as follows:

[0139] (a) Select the original dataset for K-means clustering, and randomly select k spectral samples from it as the initial clustering centers z1, z2, …, zk ;

[0140] (b) Calculate the distances from all spectral sample data to the k condensation points one by one (usually using the Euclidean distance as the distance from the sample to the clustering center). Divide the n samples (or variables) into k categories according to the magnitudes of the distances. The Euclidean distance calculation formula is as follows:

[0141]

[0142] x i is the variable value of the i-th variable of sample x, and y i is the variable value of the i-th variable of sample y. If the spectral sample is closest to the distance of its original class, it remains in the original class; otherwise, it is moved to the class with the closest distance to it;

[0143] (c) Calculate the clustering center of each category of data in the k categories. If the clustering center does not coincide with the initial clustering center, use this clustering center as the new clustering center and repeat step (b) until all spectral samples cannot be moved, or until each clustering center no longer changes, then the calculation process terminates, thereby identifying the source of the engine plume particulate matter.

[0144] Through a large number of plume radiation spectrum clustering analyses, specific wavelength characteristics for particulate source identification can be obtained, so that it is not necessary to obtain the radiation light wavelength intensity data of all bands, only the data of several determined wavelengths are required, and the test device and the particulate source identification algorithm can be further simplified.

[0145] Furthermore, in the engine plume characteristic signal test method provided in this embodiment, the above-mentioned radiation parameter inversion algorithms such as plume radiation temperature, emissivity, and radiation intensity are established based on the Planck radiation law parameter fitting method.

[0146] The measured radiation intensities of the plume at different wavelengths are:

[0147]

[0148] ε is the average emissivity of the plume, and its value is a constant between 0 and 1; T is the average thermodynamic temperature of the field of view, and k is the correction coefficient for different wavelength detection responses, which is related to the photoelectric detection response, optical fiber transmission, and relevant parameters of the test system.

[0149] According to the measurement conditions and calculation range, when λT << 2000μmT, the Planck radiation law can be simplified to the Wien relation:

[0150]

[0151] Take the logarithm of both sides of the above equation. Let ε’ = lnε, t = 1 / T, and substitute ε’ and t into the above equation to obtain:

[0152]

[0153] Establish a multivariate function f(ε’,t) and use the polynomial y i for curve fitting:

[0154]

[0155] y i is the logarithm of the radiation intensity obtained from experimental measurements at a wavelength of λ i According to the least squares method, when the sum of the squares of the deviations in the above equation is minimized, the corresponding values of ε’ and t are calculated, and substituting them back into the formulas ε’ = lnε, t = 1 / T, the average temperature and radiation rate parameters obtained from experimental measurements can be obtained.

[0156] On the basis of obtaining the plume radiation temperature and radiation rate parameters here, according to Planck's law, the plume radiation intensities at different wavelengths in the entire wavelength range such as ultraviolet, visible, and infrared bands can be calculated, and the total radiation intensity can be obtained through integration over the entire wavelength range.

[0157] Example Two

[0158] This embodiment provides an engine plume characteristic signal testing device. As Figure 2 shown, the other structures of this embodiment are the same as those of the first embodiment, except that a flue 10 is added. The flue 10 is arranged outside the engine 11 and the engine plume 12. The engine 11 is arranged inside the flue 10. The flue 10 is used to avoid the influence of the external environment on the engine plume 12 and collect the smoke generated during the engine 11 test. To reduce the influence of the flue on the operation of the engine 11, the flue 10 is designed to be more than 20 times the size of the plume size. It can also be an enclosed engine test chamber or laboratory. Optical windows 101 and 102 are symmetrically arranged on the flue 10 corresponding to the area to be measured of the engine plume 13.

[0159] Outside the optical windows 101 and 102, the laser light source part 2 and the light receiving part 3 of the corresponding engine plume characteristic signal testing device are respectively arranged.

[0160] Functions and Effects of the Embodiment

[0161] The engine plume characteristic signal testing device and method provided by the embodiment have the following functions and effects:

[0162] (1) The embodiment establishes an analysis algorithm for the characteristic signals of the engine plume by measuring the radiation energy distribution in the ultraviolet, visible, and infrared bands of the plume, as well as the attenuation degree of lasers with different wavelengths passing through the plume to be measured, and synchronously obtains particle parameters such as the particle size, concentration, composition, and source identification of the plume, and radiation parameters such as the radiation temperature, emissivity, and radiation intensity, thereby evaluating the characteristic signals of the engine plume, without the need for multiple test devices to obtain the characteristic signals of the engine plume at different wavelengths, further simplifying the test device and method for the characteristic signals of the engine plume.

[0163] (2) The embodiment provides two implementation methods, namely direct plume testing and flue testing, and by controlling the working modes of the laser light source part and the light receiving part, three working modes, namely radiation measurement, particle measurement, and synchronous measurement, are formed, which very conveniently meet the synchronous testing of particle parameters such as the particle size, concentration, composition, and source identification of the plume and radiation parameters such as the radiation temperature, emissivity, and radiation intensity under different test requirements, thereby evaluating the characteristic signals of the engine plume.

[0164] (3) When the synchronous measurement working mode is adopted in the embodiment, the intensity data of the mixed light of the radiation light and the transmitted laser with different wavelengths are detected and obtained. Through data conversion, the accurate light intensity data of the transmitted laser in the mixed light can be obtained, thereby realizing the synchronous testing of particle parameters such as the particle size, concentration, composition, and source identification of the plume and radiation parameters such as the radiation temperature, emissivity, and radiation intensity.

[0165] (4) For the selection of the laser wavelengths, intensities, working modes of multiple lasers in the laser light source part of the embodiment, the filtering wavelength range, attenuation rate, working mode of the filter attenuator in the light receiving part, and the data wavelengths of the photoelectric detection part, etc., need to be selected and determined in combination with parameters such as the particle size parameter range of the engine plume particles, the particle concentration parameter concentration, and the plume radiation spectrum. The laser wavelength is usually selected as blue-violet light, which can ensure that the measurement of the laser light intensity is not affected by the radiation light and improve the test accuracy of the particle size and concentration parameters.

[0166] The above implementation methods are preferred cases of the present invention and are not used to limit the protection scope of the present invention.

[0167] Those skilled in the technical field to which the present invention belongs can make various modifications or supplements to the described specific embodiments or use similar ways to replace them, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. An engine plume characteristic signal testing device is used to measure the radiation energy distribution of the engine plume and the attenuation degree of lasers with different wavelengths after passing through the plume to be tested. It is characterized in that: The engine plume characteristic signal testing device has three working modes: radiation measurement, particle measurement, and synchronous measurement. It synchronously obtains particle parameters including plume particle size, concentration, composition, and source identification, and radiation parameters including radiation temperature, emissivity, and radiation intensity, and then evaluates the engine plume characteristic signal, including: A laser light source unit, located on one side of the engine plume, is used to generate incident lasers with different wavelengths; An optical receiving unit, located on the other side of the engine plume, is used to filter, converge, and receive radiation light or transmitted laser; An optoelectronic detection unit, connected to the optical receiving unit through an optical fiber, is used to detect the intensity of light with different wavelengths received and converged by the optical receiving unit; and A characteristic signal testing and processing unit is used to control the working mode of the laser light source unit, wherein the characteristic signal testing and processing unit is respectively communicatively connected to the laser light source unit and the optoelectronic detection unit, controls the working modes of the laser light source unit and the optoelectronic detection unit according to the three working modes of radiation measurement, particle measurement, and synchronous measurement of the testing device, and processes, stores, and displays the engine plume characteristic signal parameters, the laser light source unit includes a laser controller and multiple lasers, the characteristic signal testing and processing unit controls the working mode of the laser controller, the laser wavelength, and the laser output intensity parameters, and the laser controller is controlled by the characteristic signal testing and processing unit through a control signal cable to turn on and off two working modes, the laser wavelength, and the laser output intensity parameters, the optical receiving unit includes a filtering attenuator, and the filtering attenuator has two working modes: light filtering and non-light filtering, In the working mode of radiation measurement, the laser light source unit adopts the off working mode, the optical receiving unit adopts the non-light filtering working mode, the optical receiving unit is used to converge and obtain the plume radiation light, and the optoelectronic detection unit directly detects the intensity of plume radiation light with different wavelengths in the ultraviolet, visible, and infrared bands to obtain radiation parameters including plume radiation temperature, emissivity, and radiation intensity; In the working mode of particle measurement, the laser light source unit adopts the on working mode, the optical receiving unit adopts the light filtering working mode, the optical receiving unit is used to filter the plume radiation light and converge the transmitted lasers with different wavelengths, and the optoelectronic detection unit detects the intensity of the transmitted lasers with different wavelengths after filtering the plume radiation light to obtain plume particle size and concentration parameters, and then evaluates the engine plume characteristic signal; In the working mode of synchronous measurement, the laser light source unit adopts the on working mode, the optical receiving unit adopts the non-light filtering working mode, the optical receiving unit is used to converge and obtain the mixed light of plume radiation light and transmitted laser, and the optoelectronic detection unit detects the intensity of the mixed light of radiation light and transmitted laser with different wavelengths to synchronously obtain particle parameters including plume particle size, concentration, composition, and source identification, and radiation parameters including radiation temperature, emissivity, and radiation intensity.

2. The engine plume characteristic signal testing device according to claim 1, characterized in that: Among them, The laser light source unit further includes an optical fiber coupler and a collimator. The laser generated by the laser is output to the optical fiber coupler through an optical fiber. The optical fiber coupler receives the laser generated by the laser and couples the laser to the output optical fiber. The collimator is connected to the optical fiber coupler and outputs laser light to irradiate the measurement area.

3. The engine plume characteristic signal testing device according to claim 1, wherein: Among them, The light receiving unit further includes a light collecting optical fiber coupler. The plume radiation light, the laser generated by the laser light source unit, or the mixed light of both enters the optical fiber coupler through the filter attenuator and is then output.

4. The engine plume characteristic signal testing device according to claim 3, wherein: Among them, The photoelectric detection unit includes a collimator, a plurality of gratings, a plurality of photodetectors, and a photoelectric detection processor. The collimator is connected to the optical fiber coupler through an optical fiber, and the collimated laser light after collimating the laser light output by the light receiving unit is irradiated on the grating. After receiving the collimated laser light, the grating is divided into multiple beams of light according to the wavelength. The plurality of photodetectors respectively receive the multiple beams of light and convert the optical signal into an electrical signal and output it through a cable. The photoelectric detection processor collects the electrical signals output by the plurality of photodetectors, converts the electrical signals into digital signals, obtains the intensities of lights with different wavelengths, and outputs them to the characteristic signal testing and processing unit through a digital signal communication cable.

5. The engine plume characteristic signal testing device according to claim 2, wherein: Among them, The characteristic signal testing and processing unit is connected to the laser light source unit and is used to control the generation and shutdown, wavelength, and intensity of the incident laser. The characteristic signal testing and processing unit is connected to the light receiving unit and is used to control the working mode of the light receiving unit. The characteristic signal testing and processing unit is connected to the photoelectric detection unit and is used to obtain the intensities of plume radiation lights with different wavelengths, the intensities of transmitted laser lights with different wavelengths, and the intensities of the mixed light of radiation lights and transmitted laser lights with different wavelengths, and synchronously obtain plume particle and radiation parameters based on the established engine plume characteristic signal analysis algorithm.

6. A method for testing the engine plume characteristic signal by using the engine plume characteristic signal testing device according to any one of claims 1-5, characterized in that, It includes the following steps: S1: Arrange the engine plume characteristic signal testing device. S2: Determine the working mode of the engine plume characteristic signal testing device, turn on the testing device, and record, process, and save the initial optical signal detected by the photoelectric detection unit before the test. S3: According to the working mode of the engine plume characteristic signal testing device and the test requirements, set the test timing sequence, and carry out the plume characteristic signal test according to the timing sequence, and record, process, and save the optical signal detected by the photoelectric detection unit. S4: Based on the established plume characteristic signal inversion algorithm, obtain the engine plume particle parameters and radiation parameters, and further evaluate the engine plume characteristic signal.

7. The method for testing the engine plume characteristic signal according to claim 6, wherein: Among them, The particle size and concentration parameter synchronous inversion algorithm is established based on the fact that the attenuation degree of lasers with different wavelengths after passing through the plume to be measured conforms to the Beer-Lambert law. The relationship between the attenuation degrees of lasers with different wavelengths after passing through the plume to be measured is as follows: Subscript λ i represents different wavelengths; T is the transmittance, which is the ratio of the transmitted light intensity I to the initial light intensity I0; Q ext is a proportionality constant, which is related to at least the laser wavelength and particle parameters; L is the plume thickness; N D is the particle concentration, f(D) is the particle size distribution function. Thus, by experimentally measuring the transmitted light intensity I of the laser at different wavelengths and the initial light intensity I0, the plume transmittance T is obtained. Thus, a linear equation system is obtained by experimentally measuring the attenuation of lasers with different wavelengths after passing through the plume to be measured: E = Af Each element in the extinction coefficient matrix A can be expressed as where N is the number of particle size bins, c j is the numerical integration coefficient, f = [f(D1), f(D2),..., f(D j )] T is the particle size distribution function of the particle system to be measured, which is obtained by solving a system of linear equations. On this basis, the concentration of the particles to be measured is obtained through the Beer-Lambert law.

8. The method for testing the engine plume characteristic signal according to claim 7, wherein: Among them, The particle component inversion algorithm is based on the fact that particles in the high-temperature engine plume emit characteristic spectral lines with strong enough ultraviolet, visible or infrared band radiation, and the particle components are determined through the characteristic spectral lines. Under normal conditions, the outer electrons of the atoms of the particles in the plume are in the ground state. When excited by the high-temperature environment outside, the excited atoms are in a very unstable state, and the outer electrons will spontaneously transition from a high energy level to a low energy level, while releasing photons. The spontaneous emission frequency ν of the atoms is related to the energy level difference (E1 - E2) and satisfies: hν = E1 - E2 h is Planck's constant. When the system is in a thermal equilibrium state, the distribution of atoms among various energy stationary states follows the Boltzmann distribution: N n and N1 are the numbers of atoms in the excited state and the ground state respectively, g n and g1 are the numbers of atoms and statistical weights in the excited state and the ground state respectively, E 1n is the excitation energy required from the ground state to the excited state, k is the Boltzmann constant, T is the temperature at which the atoms are located. Thus, the particle components can be determined and the component concentrations can be obtained through the analysis of the characteristic spectral line wavelength and intensity. The particle source identification algorithm is mainly obtained based on the K-means clustering algorithm for plume radiation spectrum clustering analysis. The basic idea of K-means clustering is to randomly select k data samples from a dataset containing a large number of radiation spectrum samples of solid particulate matters as the initial clustering centers, calculate the distances between each spectrum sample and the k initial clustering centers, divide all spectral data into the categories represented by the clustering centers with the closest distances to them, update the k clustering centers according to the means of the spectral samples in the newly generated categories. If the change in the clustering center values within adjacent iteration times exceeds the set threshold, then re-classify all spectral samples according to the new clustering centers; if the change in the clustering center values within adjacent iteration times is less than the specified threshold, the algorithm converges and outputs the clustering result. The flow of the K-means clustering algorithm is as follows: (a) Select the original dataset for K-means clustering and randomly select k spectral samples from it as the initial clustering centers z1, z2, …, z k ; (b) Calculate the distances from all spectral sample data to the k condensation points one by one (usually using the Euclidean distance as the distance from the sample to the clustering center), and divide the n samples (or variables) into k categories according to the distances. The Euclidean distance calculation formula is as follows: x i is the variable value of the i-th variable of sample x, y i is the variable value of the i variables of sample y. If the spectral sample is closest to the class it originally belonged to, it remains in the original class; otherwise, it is moved to the class that is closest to it. (c) Calculate the clustering centers of each of the k categories of data. If the clustering center does not coincide with the initial clustering center, then use this clustering center as the new clustering center and repeat step (b) until all spectral samples cannot move, or until each clustering center no longer changes, then the calculation process terminates, thereby identifying the source of the engine plume particulate matter.

9. The method for testing the engine plume characteristic signal according to claim 7, wherein: The radiation parameter inversion algorithms for the plume radiation temperature, emissivity, and radiation intensity are established based on the Planck radiation law parameter fitting method. The measured radiation intensities of the plume at different wavelengths are: ε is the average emissivity of the plume, and its value is a constant between 0 and 1; T is the average thermodynamic temperature of the field of view, k is the correction coefficient for different wavelength detection responses, and this coefficient is related to the photoelectric detection response, optical fiber transmission, and relevant parameters of the test system. According to the measurement conditions and calculation range, in the case of λT << 2000μmT, the Planck radiation law is simplified to the Wien relation: Take the natural logarithm of both sides of the above equation, let ε’ = lnε, t = 1 / T, and substitute ε’ and t into the above equation to obtain: Establish a multivariate function f(ε’,t) using the polynomial y i Perform curve fitting: y i is the logarithm of the radiation intensity obtained from experimental measurement at a wavelength of λ i According to the least squares method, when the sum of the squares of the deviations in the above formula is minimized, the corresponding ε’ and t values are calculated and substituted back into the formulas ε’ = lnε and t = 1 / T, thus obtaining the average temperature and radiation rate parameters obtained from experimental measurement. Based on the plume radiation temperature and emissivity parameters obtained herein, the plume radiation intensity at different wavelengths in the full wavelength range including ultraviolet, visible, and infrared bands is calculated according to Planck's law, and the total radiation intensity is obtained through full-wavelength integration.

10. An engine plume characteristic signal testing device for measuring the radiation energy distribution of an engine plume and the attenuation degree of different-wavelength lasers after passing through the plume to be measured, characterized in that: The engine plume characteristic signal testing device has three working modes: radiation measurement, particle measurement, and synchronous measurement. Particle parameters including plume particle size, concentration, composition, and source identification and radiation parameters including radiation temperature, emissivity, and radiation intensity are obtained synchronously, and then the engine plume characteristic signal is evaluated, including: A flue, arranged outside the engine and the engine plume, for collecting the smoke generated during the engine test. Two optical windows are symmetrically arranged on the flue. A laser light source unit, located on one side of one of the optical windows, for generating incident lasers of different wavelengths. A light receiving unit, located on one side of the other optical window, for filtering, converging, and receiving radiation light or transmitted laser light. A photoelectric detection unit, connected to the light receiving unit through an optical fiber, for detecting the intensity of light of different wavelengths converged and received by the light receiving unit. And A characteristic signal testing and processing unit, for controlling the working mode of the laser light source unit. Among them, the characteristic signal testing and processing unit is respectively communicatively connected to the laser light source unit and the photoelectric detection unit, controls the working modes of the laser light source unit and the photoelectric detection unit according to the three working modes of radiation measurement, particle measurement, and synchronous measurement of the testing device, and processes, stores, and displays the engine plume characteristic signal parameters. The laser light source unit includes a laser controller and multiple lasers. The characteristic signal testing and processing unit controls the working mode of the laser controller, the laser wavelength, and the laser output intensity parameters. The laser controller is controlled by the characteristic signal testing and processing unit through a control signal cable to turn on and off two working modes, the laser wavelength, and the laser output intensity parameters. The light receiving unit includes a filter attenuator, which has two working modes: with light filtering and without light filtering. In the working mode of radiation measurement, the laser light source unit adopts the off working mode, the light receiving unit adopts the non-filtering working mode, the light receiving unit is used to converge and obtain the plume radiation light, and the photoelectric detection unit directly detects the intensity of plume radiation light of different wavelengths in the ultraviolet, visible, and infrared bands to obtain radiation parameters including plume radiation temperature, emissivity, and radiation intensity. In the working mode of particle measurement, the laser light source unit adopts the on working mode, the light receiving unit adopts the filtering working mode, the light receiving unit is used to filter the plume radiation light and converge the transmitted lasers of different wavelengths, and the photoelectric detection unit detects the intensity of the transmitted lasers of different wavelengths after filtering the plume radiation light to obtain plume particle size and concentration parameters, and then evaluate the engine plume characteristic signal. In the working mode of the synchronous measurement, the laser light source unit adopts an on working mode, and the light receiving unit adopts a non-filtering working mode. The light receiving unit is used to converge and obtain the mixed light of plume radiation light and transmitted laser. The photoelectric detection unit detects the intensity of the mixed light of radiation light and transmitted laser with different wavelengths, and is used to synchronously obtain particle parameters including plume particle size, concentration, component, source identification, etc. and radiation parameters including radiation temperature, emissivity, radiation intensity, etc.

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