A solid rocket engine plume smoke particle testing device and method

Abstract

According to the solid rocket engine plume smoke particle testing device and method of the present invention, the solid rocket engine plume smoke particle testing device includes a laser modulation part, which is located between the engine plume and the laser light source part, and modulates the spot size, beam expansion angle, and laser spatial parameters of the effective irradiation measurement area of ​​the incident laser; a laser receiving part, which is located on the other side of the engine plume, and the laser receiving part is used to converge and receive transmitted lasers of different wavelengths after passing through the plume to be measured, and split them into two beams of light, a first light beam and a second light beam, through a semi-transparent and semi-reflective mirror; a laser diffraction detection part receives the first light beam and is used to detect the diffracted light energy distribution of the first light beam; a laser attenuation detection part receives the second light beam and then irradiates the grating and then splits it into multiple beams of laser light according to wavelength; a particle test processing part is used to control the laser light source part, and the particle test processing part is communicated with the laser diffraction detection part and the laser attenuation detection part respectively, and is used to process and display the solid rocket engine plume smoke particle parameters.

Description

Technical Field

[0001] The invention belongs to the field of aerospace propulsion technology and relates to a solid rocket engine plume smoke particle testing device and method. Background Art

[0002] Solid rocket engines are widely used in the field of aerospace propulsion due to their high reliability and good performance. With the rapid development of military and aerospace, more and more requirements are placed on solid rocket engines. The development of propellant formula is no longer a one-sided pursuit of higher energy, but has gradually transformed into a comprehensive indicator such as pursuing low characteristic signals while ensuring energy performance. The exhaust plume of a solid rocket engine is a combustion product discharged from the nozzle at supersonic speed. It will further diffuse and expand at the nozzle outlet to form a luminous and hot plume flow field. Its interaction with the surrounding environment will form smoke, radiation, and attenuation of detection or guidance signals. These effects are collectively referred to as the characteristic signals of the exhaust plume.

[0003] The engine exhaust plume will produce thick smoke, which contains a large amount of high-temperature liquid and solid particles, which will cause corrosion and contamination to the fuselage of the carrier, interfere with carrier communications, and cause signal attenuation. The engine plume particle parameters are an important representation of these adverse effects. However, the particle size of these plume particle parameters has multiple orders of magnitude (from nanometers to millimeters), the particle concentration also has a large range, and the temperature is high and the radiation is strong, which brings great challenges to the plume particle parameter testing. At present, the collection method is mainly used to obtain engine plume particles, but this method has limited efficiency in collecting particles. The error of the cold state test after collection is larger than that of the actual high-temperature state. At present, there is no effective online testing method to evaluate the parameters of solid rocket engine plume smoke particles. Summary of the invention

[0004] One of the purposes of the present invention is to provide a solid rocket engine plume smoke particle testing device and method, by measuring the diffraction light energy distribution and attenuation degree of lasers of different wavelengths after passing through the plume to be tested, the solid rocket engine plume smoke particle parameters are obtained based on an established smoke particle inversion algorithm, and then the solid rocket engine plume smoke particle characteristic signals are evaluated.

[0005] The present invention provides a solid rocket engine plume smoke particle testing device, which has the following characteristics: a laser light source part, located on one side of the engine plume, used to generate incident lasers of different wavelengths; a laser modulation part, located between the engine plume and the laser light source part, used to receive the incident laser, and modulate the spot size, beam expansion angle, and laser spatial parameters of the effective irradiation measurement area of ​​the incident laser; a laser receiving part, located on the other side of the engine plume, used to converge and receive transmitted lasers of different wavelengths after passing through the plume to be measured, and split them into two beams, a first light beam and a second light beam, through a semi-transparent and semi-reflective mirror; a laser diffraction detection part, which receives the first light beam and is used to detect the diffracted light energy distribution of the first light beam; a laser attenuation detection part, which receives the second light beam and irradiates a grating and then splits the grating into multiple split laser beams according to wavelength; and a particle testing processing part, which is used to control the laser light source part, wherein the particle testing processing part is communicatively connected with the laser diffraction detection part and the laser attenuation detection part, respectively, and is used to process, store and display solid rocket engine plume smoke particle parameters.

[0006] The solid rocket engine plume smoke particle testing device provided by the present invention may also have the following features: wherein the laser light source unit includes a laser controller, multiple lasers, a fiber optic coupler, and a fiber optic collimator; the laser controller is respectively connected to the multiple lasers to control multiple lasers of different wavelengths to generate lasers; the laser generated by the laser is output to the fiber optic coupler via the optical fiber; the fiber optic coupler receives the laser generated by the laser and couples the laser into the output optical fiber; the fiber optic coupler is connected to the collimator via the output optical fiber.

[0007] In addition, the solid rocket engine plume smoke particle testing device provided by the present invention may also have the following characteristics: wherein, the laser modulation unit includes a Gaussian lens and an aperture, and the laser modulation unit receives the incident laser emitted by the laser light source unit, and modulates the spot size, beam expansion angle, and laser spatial parameters of the effective irradiation measurement area of ​​the incident laser by setting the position parameters of the Gaussian lens and the aperture, and modulates the incident laser into a convergent Gaussian laser beam that irradiates the measurement area in the plume and is positioned in the Rayleigh region of the Gaussian beam, thereby controlling the position and size of the effective irradiation measurement area, so that the object represented by the measurement result can be controlled.

[0008] In addition, the solid rocket engine plume smoke particle testing device provided by the present invention may also have the following characteristics: wherein, the laser receiving part includes a bandpass filter, a semi-transparent and semi-reflective mirror, a focusing lens, and an optical fiber coupler which are sequentially arranged along the incident light path; after the bandpass filter filters the solid rocket engine exhaust plume radiation signal, the laser receiving part splits the Gaussian laser into a first light beam and a second light beam through the semi-transparent and semi-reflective mirror; the first light beam is output to the laser diffraction detection part, and the second light beam is converged by the focusing lens into the optical fiber coupler and output to the laser attenuation detection part, and the transmitted laser diffraction light energy distribution and intensity are obtained synchronously, thereby synchronously obtaining the particle size measurement of different particle ranges based on the extinction spectrum particle inversion algorithm and the laser diffraction particle inversion algorithm.

[0009] In addition, the solid rocket engine plume smoke particle testing device provided by the present invention may also have the following characteristics: wherein, the laser diffraction detection unit includes a narrow-band filter, a planar detector and a laser diffraction processor which are arranged in sequence, the laser diffraction detection unit is located on one side of the laser receiving unit, the narrow-band filter controls the wavelength of the first light beam, the planar detector receives the first light beam and performs photoelectric conversion, and may be composed of dozens of concentric semicircular ring detectors, or fan-shaped rings, or a photoelectric detector array, and output to the laser diffraction processor, the laser diffraction processor and the planar detector are connected by a cable, and the electrical signal is converted into a digital signal to obtain the distribution of the transmitted laser diffraction light energy.

[0010] In addition, the solid rocket engine plume smoke particle testing device provided by the present invention may also have the following features: wherein, the laser attenuation detection unit includes a collimator, a grating, multiple photoelectric detectors and a laser attenuation processor, the collimator and the fiber coupler are connected through an optical fiber, the collimated laser after the fiber laser is collimated output by the laser receiving unit is irradiated on the grating, the grating receives the collimated laser and divides it into multiple beams of sub-laser light according to the wavelength, multiple photoelectric detectors respectively receive the multiple beams of sub-laser light and convert the optical signals into electrical signals and output them to the laser attenuation processor through cables, the laser attenuation processor collects the electrical signals output by the multiple photoelectric detectors and converts the electrical signals into digital signals, thereby obtaining the intensity of transmitted lasers of different wavelengths.

[0011] A method for testing solid rocket engine plume smoke particles using any of the solid rocket engine plume smoke particle testing devices described above, characterized in that it comprises the following steps:

[0012] S1: Install the solid rocket engine plume smoke particle test device on both sides of the plume;

[0013] S2: Turn on the laser controller, drive the laser to generate laser, turn on the laser diffraction detection unit and the laser attenuation detection unit, and respectively record, process and save the initial laser light energy distribution and intensity received by the detection;

[0014] S3: Start the test, turn on the laser diffraction detection unit and the laser attenuation detection unit at the same time, and respectively record, process and save the energy distribution and intensity of the transmitted laser diffraction light received by the detection;

[0015] S4: Obtain the solid rocket motor plume smoke particle parameters based on the established smoke particle inversion algorithm;

[0016] S5: Evaluate the signature of solid rocket motor plume smoke particles.

[0017] In addition, the method for testing solid rocket engine plume smoke particles provided by the present invention may also have the following characteristics: different detection data are used for different particle size ranges, and solid rocket engine plume smoke particle parameters are obtained based on different smoke particle inversion algorithms. For the particle size range of 0.06 to 10 μm, the laser attenuation detection unit is used to obtain laser attenuation degree data of different wavelengths, and the particle parameters are obtained based on the extinction spectrum particle inversion algorithm. For the particle size range above 10 μm, the transmitted laser diffraction light energy distribution is obtained by the laser diffraction detection unit, and the particle parameters are obtained based on the laser diffraction particle inversion algorithm under Gaussian light irradiation conditions.

[0018] In addition, the method for testing solid rocket engine plume smoke particles provided by the present invention may also have the following characteristics: the characteristic signal of the solid rocket engine plume smoke particles is evaluated by combining the particle size range of 0.06 to 10 μm and the particle size range of more than 10 μm, and two algorithms are used for synchronous testing and processing to comprehensively form the final test results.

[0019] In addition, in the method for testing solid rocket engine plume smoke particles provided by the present invention, the attenuation degree of lasers of different wavelengths after passing through the plume to be tested conforms to the Beer-Lambert law, and the relationship is as follows:

[0020]

[0021] Subscript λ i Indicates different wavelengths; T is the transmittance, which is the sum of the transmitted light intensity I and the initial light intensity I 0 Ratio; Q ext is a proportional constant, which is related to the laser wavelength, smoke particle parameters, etc.; L is the plume thickness; N D is the smoke particle concentration, f(D) is the smoke particle size distribution function, and the transmitted light intensity I and the initial light intensity I of different wavelengths of laser are measured experimentally. 0 The plume transmittance T is obtained, and the linear equations are obtained by attenuating lasers of different wavelengths after passing through the plume to be measured:

[0022] E=Af

[0023] 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 classifications, c j is the numerical integration coefficient. f=[f(D 1 ),f(D 2 ),…,f(D j )] T is the particle size distribution function of the particles to be tested.

[0024] In addition, the method for testing solid rocket engine plume smoke particles provided by the present invention may also have the following characteristics: according to the Fraunhofer diffraction theory and the Babinet principle, a laser diffraction particle inversion algorithm under Gaussian light irradiation conditions is obtained, and the expression of the diffraction light intensity distribution I of the spherical particles under parallel light irradiation is:

[0025]

[0026] I 0 is the incident light intensity of parallel light, f is the focal length of the Fourier lens, λ is the wavelength, D is the particle diameter, X=πDsinθ / λ, θ is the diffraction angle, J 1 is a first-order Bessel function. According to the characteristics of the Bessel function, it can be found that when X = 0, 2J 1 (X) / X=1, in the spherical coordinate system (r,θ,φ), the scattering amplitude S of a spherical particle under the irradiation of a Gaussian beam is 1 and S 2 It can be expressed as:

[0027]

[0028] a n and b n is the Mie scattering coefficient, and is the light form factor, and is the scattering angle function, n and m are Legendre polynomial series, and i is a complex number. The scattered light intensity distribution of the particle is:

[0029]

[0030] In the problem of particle diffraction under Gaussian beam irradiation, the light intensity of the incident beam is non-uniformly distributed, but the Fraunhofer diffraction theory and the Babinet principle still hold true. Therefore, the distribution of particle diffraction light energy under Gaussian beam irradiation can also be derived based on the above two principles, and obtained by the planar detector of the laser diffraction detection unit:

[0031]

[0032] Subscript n represents the nth ring, S is the radius, S n,1 is the inner radius of the nth ring, S n,2 is the outer radius of the nth ring, and the corresponding diffraction angle is θ n,1 and θ n,2 , n=1,2,…,M, where M is the total number of multi-element photodetector rings.

[0033] When the focal length f of the Fourier lens is much larger than the maximum radius of the photodetector, that is, the diffraction angle is very small, the light energy distribution can be simplified;

[0034]

[0035] X n,1 =πDθ n,1 / λ,X n,2 =πDθ n,2 / λ, D and λ are the particle size and the wavelength of the incident light beam. After integrating the above formula, the diffraction light energy on the nth ring can be obtained as:

[0036]

[0037] The above formula is based on the case where there is only one particle in the measurement area. If there are many particles of different sizes in the measurement area, or a particle group, and the diameter is assumed to be D i The number of particles is N i , the subscript i represents the particle size classification, i = 1, 2, ..., K. At this time, the total diffraction light energy on the nth ring is:

[0038]

[0039] The total diffracted light energy can be expressed in matrix form:

[0040] E=TW

[0041] E=(e 1 ,e 1 ,…,e M ) T is the light energy distribution column vector, W=(W 1 ,W 1 ,…,W M ) T is the particle size distribution column vector, and

[0042]

[0043] is the light energy distribution coefficient matrix, each element t in the matrix i,n The physical meaning is that the diameter per unit weight is D i The diffraction generated by the particles falls on the nth ring of the photodetector. Thus, the corresponding relationship between the laser diffraction light energy distribution and the particle size distribution is established. The light energy distribution column vector E can be measured by a planar detector through experiments, and the light energy distribution coefficient matrix T can be calculated by diffraction theory, and then the particle size distribution, particle number distribution, or particle volume distribution can be obtained. On this basis, by setting the laser of the laser light source part with different wavelengths in combination with the narrow-band filter of the laser diffraction detection part, the particle laser diffraction light energy distribution of multiple wavelengths can be obtained, and the test accuracy can be further improved by inverting the multi-wavelength light energy distribution.

[0044] Functions and Effects of the Invention

[0045] The solid rocket engine plume smoke particle testing device and method involved in the present invention have the following inventive functions and effects:

[0046] (1) The present invention measures the diffraction light energy distribution and attenuation degree of lasers of different wavelengths after passing through the measured plume, obtains the particle parameters of the engine plume under the actual high-temperature state based on the established smoke particle inversion algorithm, realizes the online test of solid rocket engine plume smoke particles, and further evaluates the characteristic signals of solid rocket engine plume smoke particles.

[0047] (2) The laser modulation unit of the present invention adopts a Gaussian lens and an aperture. By setting the position, focal length and other parameters of the Gaussian lens and the aperture, the laser spatial parameters such as the spot size, beam expansion angle, and effective irradiation measurement area of ​​the incident laser are modulated, and the incident laser is modulated into a convergent Gaussian beam to illuminate the plume measurement area, and the effective irradiation measurement area is positioned in the Rayleigh region of the Gaussian beam, thereby realizing the control and adjustment of the effective irradiation measurement area, so as to achieve both average measurement of a larger space of the engine plume and local measurement of a small space, thereby obtaining the effect of the spatial distribution of particle parameters within the plume space.

[0048] (3) The present invention splits the transmission into two beams of light through a laser receiving unit, one of which is focused by a focusing lens and enters a fiber coupler and outputs a fiber laser from the optical fiber to a laser attenuation detection unit, and the other is a spatial laser, which is output to illuminate a laser diffraction detection unit, thereby synchronously obtaining the energy distribution and intensity of the diffracted light of the transmitted laser, thereby synchronously obtaining particle size measurements of different particle ranges based on the extinction spectrum particle inversion algorithm and the laser diffraction particle inversion algorithm, and comprehensively forming the final test results, effectively broadening the particle size measurement range and improving the measurement accuracy.

[0049] (4) The selection of the laser wavelength and intensity of the multiple lasers in the laser light source part of the present invention, the wavelength range of the bandpass filter in the laser receiving part, the wavelength of the narrowband filter in the laser diffraction detection part, and the grating parameters of the laser attenuation detection part needs to be determined in combination with parameters such as the engine plume particle size parameter range, the particle concentration parameter concentration, and the plume radiation characteristics, thereby avoiding the influence of high-temperature plume radiation on photoelectric detection and effectively improving the test accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of a solid rocket engine plume smoke particle testing device in an embodiment;

[0051] Figure 2 Schematic diagram of the principle of the solid rocket engine plume smoke particle testing method in the embodiment;

[0052] Figure 3 is a schematic diagram of a laser diffraction detection unit in an embodiment;

[0053] Figure 4 Schematic diagram of laser diffraction light energy distribution obtained in the embodiment. DETAILED DESCRIPTION

[0054] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following embodiments and the accompanying drawings specifically illustrate a solid rocket engine plume smoke particle testing device and method of the present invention.

[0055] Example

[0056] like Figure 1 As shown, this embodiment provides a solid rocket engine plume smoke particle testing device, which includes a laser light source unit 2, a laser modulation unit 3, a laser receiving unit 4, a laser diffraction detection unit 5, a laser attenuation detection unit 6, a particle testing processing unit 7, cables 71, 72, 73 and optical fibers 28, 26, 47.

[0057] The solid rocket engine plume smoke particle testing device is used for testing solid rocket engine plume smoke particles and is arranged on both sides of the exhaust plume 12 of the engine 11 to be tested.

[0058] The laser light source unit 2 is located on one side of the engine plume 12 and is used to generate incident lasers 20 of different wavelengths.

[0059] The laser modulation unit 3 is located between the engine plume 12 and the laser light source unit 2 , and is used to receive the incident laser 20 emitted by the laser light source unit 2 , modulate the laser spatial parameters such as the spot size, beam expansion angle, and effective irradiation measurement area of ​​the incident laser 20 , and output a Gaussian laser beam 30 .

[0060] The laser receiving unit 4 is located at the other side of the engine plume 12 , and is used to collect and receive the transmitted lasers 30 of different wavelengths after passing through the plume to be measured, and split them into two beams 45 and 46 .

[0061] The laser diffraction detection unit 5 receives a beam of transmitted light 45 and is used to detect the diffracted light energy distribution of the received transmitted laser 45 .

[0062] The laser attenuation detection unit 6 receives another beam of transmitted light 46 and is used to detect the intensity of the received transmitted laser light of different wavelengths.

[0063] The particle test processing unit 7 is connected to the laser diffraction detection unit 5 and the laser attenuation detection unit 6 respectively, and is used to control the laser light source unit 2, and process, store and display the solid rocket engine plume smoke particle parameters.

[0064] The laser light source unit 2 includes a laser controller 21 , lasers 22 , 23 , and 24 , a fiber coupler 27 , a fiber collimator 29 , a cable 25 , and optical fibers 26 and 28 .

[0065] 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 of different wavelengths to generate lasers. The laser controller 21 is controlled by the particle testing processing unit 7 through the control signal cable 71. The laser generated by the laser 21 is output to the fiber coupler 27 through the optical fiber 26. The fiber coupler 27 receives the laser generated by the lasers 22, 23, and 24 and couples the laser to the output optical fiber 28. The fiber coupler 27 is connected to the collimator 29 through the output optical fiber 28, and the collimator 29 outputs the laser 20.

[0066] The laser modulation unit 3 includes a Gaussian lens 31 and an aperture 32. The laser modulation unit 3 receives the incident laser 20 emitted by the laser light source unit 2. By setting the position, focal length and other parameters of the Gaussian lens 31 and the aperture 32, the laser spatial parameters such as the spot size, beam expansion angle, and effective irradiation measurement area of ​​the incident laser 20 are modulated. The incident laser is modulated into a convergent Gaussian laser beam 30 to irradiate the plume 12, and the effective irradiation measurement area 13 is positioned in the Rayleigh region of the Gaussian beam, thereby controlling the position and size of the effective irradiation measurement area, so that the object represented by the measurement result can be controlled.

[0067] The effective irradiation measurement area 13 of the engine plume particle test is determined by the position, focal length and other parameters of the Gaussian lens 31 and the aperture 32 of the laser modulation unit 3. The effective irradiation measurement area 13 can be controlled and adjusted by adjusting the Rayleigh zone of the Gaussian beam, which can achieve both average measurement of a larger space of the engine plume and local measurement of a small space, thereby obtaining the spatial distribution of particle parameters within the plume space.

[0068] The laser receiving unit 4 includes a bandpass filter 41 , a semi-transparent mirror 42 , a focusing lens 43 , and a fiber coupler 44 , which are sequentially arranged along the incident light path.

[0069] After the Gaussian incident laser 30 generated and modulated by the laser light source unit 2 and the laser modulation unit 3 passes through the plume to be measured area, the transmitted laser enters the laser receiving unit 4, and the radiation signal of the exhaust plume 12 of the solid rocket engine 11 is filtered by the bandpass filter 41, and then is split into two beams of light 45 and 46 by the semi-transparent and semi-reflective mirror 42, one of which is focused by the focusing lens 43 and enters the fiber coupler 44 and outputs the fiber laser to the laser attenuation detection unit 6 by the optical fiber 47, and the other is the space laser 45, which is output to the irradiation laser diffraction detection unit 5, and the energy distribution and intensity of the diffraction light of the transmitted laser are obtained synchronously, so as to synchronously obtain the particle size measurement of different particle ranges based on the extinction spectrum particle inversion algorithm and the laser diffraction particle inversion algorithm, and comprehensively form the final test result, which effectively broadens the particle size measurement range and improves the measurement accuracy.

[0070] The laser diffraction detection unit 5 includes a narrow-band filter 51 , a planar detector 52 and a laser diffraction processor 53 which are arranged in sequence. The laser diffraction detection unit 5 is located at one side of the laser receiving unit 4 .

[0071] like Figure 3 As shown, the laser diffraction detection unit 5 receives a beam of spatial laser 45 irradiated by the laser receiving unit 4. This beam of spatial laser 45 is a diffraction ring formed by diffraction of particles in the test area 13. The wavelength of the spatial laser 45 is controlled to a selected wavelength through a narrow-band filter 51, and is received by a planar detector 52 and photoelectrically converted. The planar detector 52 may be composed of dozens of concentric semicircular ring detectors, or fan-shaped rings, or a photoelectric detector array, and output to a laser diffraction processor 53. The laser diffraction processor 53 is connected to the planar detector 52 through a cable 54, and the electrical signal is converted into a digital signal to obtain the distribution of the diffraction light energy of the transmitted laser, and is output to the particle testing processing unit 7 through a digital signal communication cable 72.

[0072] The laser attenuation detection unit 6 includes a collimator 61 , a grating 63 , a plurality of photodetectors 65 , 66 , 67 and a laser attenuation processor 69 .

[0073] The collimator 61 is connected to the fiber coupler 44 of the laser receiving unit 4 via the optical fiber 47 , and collimates a beam of fiber laser output from the laser receiving unit 4 to obtain a laser 62 which then irradiates the grating 63 .

[0074] After receiving the laser 62, the grating 63 divides the laser into multiple sub-beams 64 according to the wavelength; after receiving the multiple sub-beams 64 respectively, the multiple photoelectric detectors 65, 66, and 67 convert the optical signals into electrical signals and output them to the laser attenuation processor 69 through the cable 68. The laser attenuation processor 69 collects the electrical signals output by the detectors 65, 66, and 67 and converts the electrical signals into digital signals, obtains the intensity of the transmitted laser at different wavelengths, and outputs them to the particle testing processing unit 7 through the digital signal communication cable 73.

[0075] The particle test processing unit 7 is connected to the laser controller 21 via a control signal cable 71 to control the generation of the incident laser, and is connected to the laser diffraction processor 53 and the laser attenuation processor 69 via digital signal communication cables 72 and 73 respectively to obtain the diffraction light energy distribution of the transmitted laser and the intensity of the transmitted laser at different wavelengths. The particle test processing unit 7 obtains the solid rocket engine plume smoke particle parameters based on the established smoke particle inversion algorithm, processes, saves and displays the solid rocket engine plume smoke particle parameters, and then evaluates the solid rocket engine plume smoke particle characteristic signals.

[0076] Furthermore, the selection of the laser wavelength and intensity of the multiple lasers 22, 23, 24 in the laser light source unit 2, the wavelength range of the bandpass filter 41 of the laser receiving unit 4, the wavelength of the narrowband filter 51 of the laser diffraction detection unit 5, and the parameters of the grating 63 of the laser attenuation detection unit 6 needs to be selected and determined in combination with parameters such as the particle size parameter range of the engine plume 12, the particle concentration parameter concentration and the plume radiation characteristics. Usually, in order to avoid the influence of plume radiation, the laser wavelength of the multiple lasers 22, 23, 24 in the laser light source unit 2 is selected to be within the blue-violet wavelength range.

[0077] Furthermore, the positions of the plurality of photodetectors 65, 66, 67 in the laser attenuation detection unit 6 are set according to the spectral splitting of the grating 63, so as to obtain the intensity of the transmitted laser light of different wavelengths.

[0078] This embodiment also provides a solid rocket engine plume smoke particle testing method, which measures the diffraction light energy distribution and attenuation degree of lasers of different wavelengths after passing through the plume to be tested, obtains the solid rocket engine plume smoke particle parameters based on an established smoke particle inversion algorithm, and then evaluates the solid rocket engine plume smoke particle characteristic signals.

[0079] Solid rocket engine plume smoke particle testing method The steps of testing solid rocket engine plume smoke particles using the solid rocket engine plume smoke particle testing device in the embodiment are:

[0080] S1: Install the solid rocket engine plume smoke particle test device on both sides of the plume;

[0081] S2: Turn on the laser controller, drive the laser to generate laser, turn on the laser diffraction detection unit and the laser attenuation detection unit, and respectively record, process and save the initial laser light energy distribution and intensity received by the detection;

[0082] S3: Start the test, turn on the laser diffraction detection unit and the laser attenuation detection unit at the same time, and respectively record, process and save the energy distribution and intensity of the transmitted laser diffraction light received by the detection;

[0083] S4: Obtain the solid rocket motor plume smoke particle parameters based on the established smoke particle inversion algorithm;

[0084] S5: Evaluate the signature of solid rocket motor plume smoke particles.

[0085] Furthermore, the solid rocket engine plume smoke particle test method uses different detection data for different particle size ranges, and obtains the solid rocket engine plume smoke particle parameters based on different smoke particle inversion algorithms:

[0086] For the particle size range of 0.06-10 μm, the attenuation degree data of lasers of different wavelengths obtained by the laser attenuation detection unit 6 are selected, and the particle parameters are obtained based on the extinction spectrum particle inversion algorithm;

[0087] For particles with a diameter of more than 10 μm, the transmitted laser diffraction light energy distribution obtained by the laser diffraction detection unit 5 is selected to obtain particle parameters based on the laser diffraction particle inversion algorithm.

[0088] In this embodiment, the characteristic signal of the solid rocket engine plume smoke particles is evaluated by combining the particle size range of 0.06 to 10 μm and the particle size range of more than 10 μm, using two algorithms for simultaneous testing and processing to comprehensively form the final test results.

[0089] Furthermore, the above extinction spectrum particle inversion algorithm is based on the fact that the attenuation degree of lasers of different wavelengths after passing through the measured plume conforms to the Beer-Lambert law.

[0090] like Figure 2 As shown in the figure, the attenuation degree of lasers with different wavelengths after passing through the measured plume is as follows:

[0091]

[0092] Subscript λ i Indicates different wavelengths; T is the transmittance, which is the sum of the transmitted light intensity I and the initial light intensity I 0 Ratio; Q ext is a proportional constant, which is related to the laser wavelength, smoke particle parameters, etc.; L is the plume thickness; ND is the smoke particle concentration, and f(D) is the smoke particle size distribution function. Therefore, by experimentally measuring the transmitted light intensity I and the initial light intensity I of different wavelengths of laser 0 Obtain the plume transmittance T. Thus, by experimentally measuring the attenuation of lasers of different wavelengths after passing through the measured plume, we can obtain a set of linear equations:

[0093] E=Af

[0094] 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 classifications, c j is the numerical integration coefficient. f=[f(D 1 ),f(D 2 ),…,f(D j )] T is the particle size distribution function of the particles to be tested.

[0095] Furthermore, the above laser diffraction particle inversion algorithm is obtained based on Fraunhofer diffraction theory and Babinet's principle. The expression of the diffraction light intensity distribution I of a spherical particle under parallel light irradiation is:

[0096]

[0097] I 0 is the incident light intensity of parallel light, f is the focal length of the Fourier lens, λ is the wavelength, D is the particle diameter, X=πDsinθ / λ, θ is the diffraction angle, J 1 is a first-order Bessel function. According to the characteristics of the Bessel function, it can be found that when X = 0, 2J 1 (X) / X=1, in the spherical coordinate system (r,θ,φ), the scattering amplitude S of a spherical particle under the irradiation of a Gaussian beam is 1 and S 2 It can be expressed as:

[0098]

[0099] a n and b n is the Mie scattering coefficient, and is the light form factor, and is the scattering angle function, n and m are Legendre polynomial series, and i is a complex number. The scattered light intensity distribution of the particle is:

[0100]

[0101] In the problem of particle diffraction under Gaussian beam irradiation, the light intensity of the incident beam is non-uniformly distributed, but the Fraunhofer diffraction theory and the Babinet principle still hold true. Therefore, the distribution of particle diffraction light energy under Gaussian beam irradiation can also be derived based on the above two principles, and obtained by the planar detector of the laser diffraction detection unit:

[0102]

[0103] Subscript n represents the nth ring, S is the radius, S n,1 is the inner radius of the nth ring, S n,2 is the outer radius of the nth ring, and the corresponding diffraction angle is θ n,1 and θ n,2 , n=1,2,…,M, where M is the total number of multi-element photodetector rings.

[0104] The laser diffraction light energy distribution obtained in a typical embodiment is as follows: Figure 4 shown.

[0105] When the focal length f of the Fourier lens is much larger than the maximum radius of the photodetector, that is, the diffraction angle is very small, the light energy distribution can be simplified;

[0106]

[0107] X n,1 =πDθ n,1 / λ,X n,2 =πDθ n,2 / λ, D and λ are the particle size and the wavelength of the incident light beam. After integrating the above formula, the diffraction light energy on the nth ring can be obtained as:

[0108]

[0109] The above formula is based on the case where there is only one particle in the measurement area. If there are many particles of different sizes in the measurement area, or a particle group, and the diameter is assumed to be D i The number of particles is N i , the subscript i represents the particle size classification, i = 1, 2, ..., K. At this time, the total diffraction light energy on the nth ring is:

[0110]

[0111] The total diffracted light energy can be expressed in matrix form:

[0112] E=TW

[0113] E=(e 1 ,e 1 ,…,eM ) T is the light energy distribution column vector, W=(W 1 ,W 1 ,…,W M ) T is the particle size distribution column vector, and

[0114]

[0115] is the light energy distribution coefficient matrix, each element t in the matrix i,n The physical meaning is that the diameter per unit weight is D i The diffraction generated by the particles falls on the nth ring of the photodetector. Thus, the corresponding relationship between the laser diffraction light energy distribution and the particle size distribution is established. The light energy distribution column vector E can be measured by a planar detector through experiments, and the light energy distribution coefficient matrix T can be calculated by diffraction theory, and then the particle size distribution, particle number distribution, or particle volume distribution can be obtained. On this basis, by setting the laser of the laser light source part with different wavelengths in combination with the narrow-band filter of the laser diffraction detection part, the particle laser diffraction light energy distribution of multiple wavelengths can be obtained, and the test accuracy can be further improved by inverting the multi-wavelength light energy distribution.

[0116] Functions and Effects of the Embodiments

[0117] The solid rocket engine plume smoke particle testing device and method provided in this embodiment have the following functions and effects:

[0118] (1) This embodiment measures the diffraction light energy distribution and attenuation of lasers of different wavelengths after passing through the measured plume, and obtains the particle parameters of the engine plume under the actual high-temperature state based on the established smoke particle inversion algorithm, thereby realizing online testing of solid rocket engine plume smoke particles and further evaluating the characteristic signals of solid rocket engine plume smoke particles.

[0119] (2) The laser modulation unit of this embodiment adopts a Gaussian lens and an aperture. By setting the position, focal length and other parameters of the Gaussian lens and the aperture, the laser spatial parameters such as the spot size, beam expansion angle, and effective irradiation measurement area of ​​the incident laser are modulated, and the incident laser is modulated into a convergent Gaussian beam to illuminate the plume measurement area. The effective irradiation measurement area is positioned in the Rayleigh region of the Gaussian beam, thereby realizing the control and adjustment of the effective irradiation measurement area, so as to achieve both average measurement of a larger space of the engine plume and local measurement of a small space, thereby obtaining the effect of the spatial distribution of particle parameters within the plume space.

[0120] (3) In this embodiment, the transmitted light is split into two beams through the laser receiving unit, one of which is focused by a focusing lens and enters the fiber coupler and outputs the fiber laser from the optical fiber to the laser attenuation detection unit, and the other is a spatial laser, which is output to illuminate the laser diffraction detection unit, thereby synchronously obtaining the energy distribution and intensity of the diffracted light of the transmitted laser, and then synchronously obtaining the particle size measurement of different particle ranges based on the extinction spectrum particle inversion algorithm and the laser diffraction particle inversion algorithm, and comprehensively forming the final test result, which effectively broadens the particle size measurement range and improves the measurement accuracy.

[0121] (4) In this embodiment, the selection of the laser wavelength and intensity of the multiple lasers in the laser light source unit, the wavelength range of the bandpass filter in the laser receiving unit, the wavelength of the narrowband filter in the laser diffraction detection unit, and the grating parameters of the laser attenuation detection unit needs to be determined in combination with parameters such as the engine plume particle size parameter range, the particle concentration parameter concentration, and the plume radiation characteristics, thereby avoiding the influence of high-temperature plume radiation on photoelectric detection and effectively improving the test accuracy.

[0122] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

[0123] Those skilled in the art to which the present invention relates may make various modifications or additions to the specific embodiments described or replace them in a similar manner, but they will not deviate from the spirit of the present invention or exceed the scope defined by the attached claims.

Claims

1. A solid rocket engine plume smoke particle testing device, used to measure the attenuation degree of lasers of different wavelengths after passing through the engine plume to be tested, It is characterized in that include: A laser light source unit, located on one side of the engine plume, for generating incident lasers of different wavelengths; A laser modulation unit is located between the engine plume and the laser light source unit, and is used to receive the incident laser, modulate the spot size, beam expansion angle, and laser spatial parameters of the effective irradiation measurement area of ​​the incident laser, and output a Gaussian laser beam; A laser receiving unit is located at the other side of the engine plume, and is used to collect and receive transmitted lasers of different wavelengths after passing through the plume to be measured, and split them into a first light beam and a second light beam through a semi-transparent and semi-reflective mirror; A laser diffraction detection unit, receiving the first light beam and used to detect the diffracted light energy distribution of the first light beam; a laser attenuation detection unit, which receives the second light beam, irradiates the grating, and then separates the second light beam into a plurality of laser beams according to wavelength; and A particle test processing unit is used to control the laser light source unit. The particle test processing unit is respectively connected to the laser diffraction detection unit and the laser attenuation detection unit for communication and is used to process, store and display the solid rocket engine plume smoke particle parameters. The laser receiving unit includes a bandpass filter, a semi-transparent and semi-reflective mirror, a focusing lens, and a fiber coupler arranged in sequence along the incident light path. After the bandpass filter filters the solid rocket engine exhaust plume radiation signal, the laser receiving unit splits the Gaussian laser into the first light beam and the second light beam through the semi-transparent and semi-reflective mirror. The first light beam is output to the laser diffraction detection unit, The second light beam is converged by the focusing lens and enters the optical fiber coupler, and is output to the laser attenuation detection unit. The energy distribution and intensity of the transmitted laser diffraction light are obtained synchronously, so that the particle size measurement of different particle ranges can be obtained synchronously based on the extinction spectrum particle inversion algorithm and the laser diffraction particle inversion algorithm.

2. The solid rocket engine plume smoke particle testing device according to claim 1, characterized in that: in, The laser light source unit includes a laser controller, multiple lasers, a fiber coupler, and a fiber collimator. The laser controller is connected to the plurality of lasers respectively, and is used to control the plurality of lasers of different wavelengths to generate lasers. The laser generated by the laser is output to the optical fiber coupler via the optical fiber. The fiber coupler receives the laser light generated by the laser and couples the laser light into the output fiber. The fiber coupler is connected to the collimator through the output fiber. The laser modulation unit includes a Gaussian lens and an aperture. The laser modulation unit receives the incident laser emitted by the laser light source unit, and modulates the spot size, beam expansion angle, and laser spatial parameters of the effective irradiation measurement area of ​​the incident laser by setting the position parameters of the Gaussian lens and the aperture, so as to modulate the incident laser into a Gaussian laser beam that converges and illuminates the measurement area in the plume and is positioned in the Rayleigh region of the Gaussian beam, thereby controlling the position and size of the effective irradiation measurement area and controlling the measurement result characterization object.

3. The solid rocket engine plume smoke particle testing device according to claim 1, characterized in that: in, The laser diffraction detection unit includes a narrow-band filter, a planar detector and a laser diffraction processor which are arranged in sequence. The laser diffraction detection unit is located on one side of the laser receiving unit. The narrowband filter controls the wavelength of the first light beam, The planar detector receives the first light beam and performs photoelectric conversion, and outputs it to the laser diffraction processor. The laser diffraction processor is connected to the planar detector via a cable, converts the electrical signal into a digital signal, and obtains the diffraction light energy distribution of the transmitted laser.

4. The solid rocket engine plume smoke particle testing device according to claim 1, characterized in that: in, The laser attenuation detection unit includes a collimator, a grating, a plurality of photodetectors and a laser attenuation processor. The collimator is connected to the fiber coupler via an optical fiber, and the collimated laser light outputted from the laser receiving unit after being collimated by the fiber laser is irradiated onto the grating. The grating receives the collimated laser and divides it into multiple sub-laser beams according to wavelengths. After receiving the plurality of split laser beams, the plurality of photoelectric detectors convert the optical signals into electrical signals and output them to the laser attenuation processor through cables. The laser attenuation processor collects the electrical signals output by the plurality of photodetectors and converts the electrical signals into digital signals, thereby obtaining the intensity of transmitted lasers of different wavelengths.

5. A method for testing solid rocket engine plume smoke particles using the solid rocket engine plume smoke particle testing device as described in any one of claims 1 to 4, It is characterized in that The following steps are involved: The solid rocket engine plume smoke particle test device is installed on both sides of the plume; Turn on the laser controller to drive the laser to generate laser light, turn on the laser diffraction detection unit and the laser attenuation detection unit, and respectively record, process and save the initial laser light energy distribution and intensity received by the detection; At the same time, the laser diffraction detection unit and the laser attenuation detection unit are turned on to respectively record, process and save the energy distribution and intensity of the transmitted laser diffraction light received by the detection; The smoke particle parameters of solid rocket engine plume are obtained based on the established smoke particle inversion algorithm. Different detection data are used for different particle size ranges, and the smoke particle parameters of solid rocket engine plume are obtained based on different smoke particle inversion algorithms. Evaluate the characteristic signature of solid rocket motor plume smoke particles, Among them, for the particle size range of 0.06-10 μm, the laser attenuation degree data of different wavelengths obtained by the laser attenuation detection unit are selected, and the particle parameters are obtained based on the extinction spectrum particle inversion algorithm. For particles with a diameter of more than 10 μm, the transmitted laser diffraction light energy distribution obtained by the laser diffraction detection unit is used to obtain the particle parameters based on the laser diffraction particle inversion algorithm under Gaussian light irradiation conditions.

6. The method for testing solid rocket engine plume smoke particles according to claim 5, characterized in that: in, According to the Mie scattering theory, the extinction spectrum particle inversion algorithm is obtained. The attenuation degree of lasers of different wavelengths after passing through the measured plume conforms to the Beer-Lambert law, and the relationship is as follows: Subscript λ i Indicates different wavelengths; T is the transmittance, which is the sum of the transmitted light intensity I and the initial light intensity I 0 Ratio; Q ext is a proportional constant, which is related to the laser wavelength, smoke particle parameters, etc.; L is the plume thickness; N D is the smoke particle concentration, f(D) is the smoke particle size distribution function, The transmitted light intensity I and the initial light intensity I of lasers with different wavelengths are measured experimentally. 0 Obtain the plume transmittance T, The linear equations obtained by attenuating lasers of different wavelengths after passing through the measured plume are: E=Af 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,LS;j=1,2,L,N), where N is the number of particle size classifications, c j is the numerical integration coefficient, f=[f(D 1 ),f(D 2 ),L,f(D j )] T is the particle size distribution function of the particles to be tested.

7. The method for testing solid rocket engine plume smoke particles according to claim 5, characterized in that: in, According to the Fraunhofer diffraction theory and the Babinet principle, the laser diffraction particle inversion algorithm under Gaussian light irradiation conditions is obtained. The expression of the diffraction light intensity distribution I of spherical particles under parallel light irradiation is: I 0 is the incident light intensity of parallel light, f is the focal length of the Fourier lens, λ is the wavelength, D is the particle diameter, X=πDsinθ / λ, θ is the diffraction angle, J 1 is a first-order Bessel function. According to the characteristics of the Bessel function, when X=0, 2J 1 (X) / X=1, in the spherical coordinate system (r,θ,φ), the scattering amplitude S of a spherical particle under the irradiation of a Gaussian beam is 1 and S 2 It can be expressed as: a n and b n is the Mie scattering coefficient, and is the light form factor, and is the scattering angle function, n and m are Legendre polynomial series, i is a complex number expression, and the scattered light intensity distribution of the particle is: In the problem of particle diffraction under Gaussian beam irradiation, the light intensity of the incident beam is non-uniformly distributed, but the Fraunhofer diffraction theory and the Babinet principle still hold true. Therefore, the distribution of particle diffraction light energy under Gaussian beam irradiation can also be derived based on the above two principles, and obtained by the planar detector of the laser diffraction detection unit: Subscript n represents the nth ring, S is the radius, S n,1 is the inner radius of the nth ring, S n,2 is the outer radius of the nth ring, and the corresponding diffraction angle is θ n,1 and θ n,2 , n=1,2,…,M, where M is the total number of multi-element photodetector rings, When the focal length f of the Fourier lens is much larger than the maximum radius of the photodetector, that is, the diffraction angle is very small, the light energy distribution can be simplified; X n,1 =πDθ n,1 / λ,X n,2 =πDθ n,2 / λ, D and λ are the particle size and the wavelength of the incident light beam. After integration, the energy of the diffracted light on the nth ring can be obtained as follows: The above formula is based on the case where there is only one particle in the measurement area. If there are many particles of different sizes in the measurement area, or called a particle group, and the diameter is assumed to be D i The number of particles is N i , i in the following table represents the particle size classification, i = 1, 2, L, K, at this time the total diffraction light energy on the nth ring is: The total diffracted light energy can be expressed in matrix form: E=TW E=(e 1 ,e 1 ,L,e M ) T is the light energy distribution column vector, W=(W 1 ,W 1 ,L,W M ) T is the particle size distribution column vector, and is the light energy distribution coefficient matrix, each element t in the matrix i,n The physical meaning is that the diameter per unit weight is D i The diffraction light energy generated by the particles falls on the nth ring of the photodetector, thereby establishing the correspondence between the laser diffraction light energy distribution and the particle size distribution. The light energy distribution column vector E can be measured by the planar detector through experiments, and the light energy distribution coefficient matrix T can be calculated through diffraction theory. Then the particle size distribution, particle number distribution, or particle volume distribution can be obtained. On this basis, by setting lasers of laser light source parts with different wavelengths in combination with narrow-band filters of laser diffraction detection parts, particle laser diffraction light energy distributions of multiple wavelengths can be obtained. The test accuracy can be further improved by inverting multi-wavelength light energy distribution.

8. The method for testing solid rocket engine plume smoke particles according to claim 5, characterized in that: in, The evaluation of the characteristic signal of solid rocket engine plume smoke particles is to combine the particle size range of 0.06 to 10μm and the particle size range of more than 10μm, use two algorithms for simultaneous testing and processing, and comprehensively form the final test results.

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