CN116044616A - Method for measuring plume divergence angle of gasification product after ignition of solid propellant - Google Patents
Method for measuring plume divergence angle of gasification product after ignition of solid propellant Download PDFInfo
- Publication number
- CN116044616A CN116044616A CN202310073468.2A CN202310073468A CN116044616A CN 116044616 A CN116044616 A CN 116044616A CN 202310073468 A CN202310073468 A CN 202310073468A CN 116044616 A CN116044616 A CN 116044616A
- Authority
- CN
- China
- Prior art keywords
- gasification product
- illuminance
- ignition
- divergence angle
- plume
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000002309 gasification Methods 0.000 title claims abstract description 114
- 238000000034 method Methods 0.000 title claims abstract description 41
- 239000004449 solid propellant Substances 0.000 title claims abstract description 38
- 238000010586 diagram Methods 0.000 claims abstract description 33
- 230000005855 radiation Effects 0.000 claims description 34
- 238000005286 illumination Methods 0.000 claims description 20
- 238000012417 linear regression Methods 0.000 claims description 11
- 238000009834 vaporization Methods 0.000 claims description 8
- 230000008016 vaporization Effects 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 7
- 238000012545 processing Methods 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims 1
- 238000005259 measurement Methods 0.000 abstract description 15
- 238000000691 measurement method Methods 0.000 abstract description 4
- 238000006243 chemical reaction Methods 0.000 description 6
- 239000000523 sample Substances 0.000 description 6
- 230000001052 transient effect Effects 0.000 description 4
- 230000001133 acceleration Effects 0.000 description 3
- 239000000835 fiber Substances 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 239000003380 propellant Substances 0.000 description 2
- 238000004611 spectroscopical analysis Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000008094 contradictory effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 238000000608 laser ablation Methods 0.000 description 1
- 238000010606 normalization Methods 0.000 description 1
- 210000001747 pupil Anatomy 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02K—JET-PROPULSION PLANTS
- F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
- F02K9/96—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof characterised by specially adapted arrangements for testing or measuring
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02K—JET-PROPULSION PLANTS
- F02K9/00—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof
- F02K9/08—Rocket-engine plants, i.e. plants carrying both fuel and oxidant therefor; Control thereof using solid propellants
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P90/00—Enabling technologies with a potential contribution to greenhouse gas [GHG] emissions mitigation
- Y02P90/30—Computing systems specially adapted for manufacturing
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention belongs to the field of measurement of a plume divergence angle of a gasification product of a thruster, and particularly relates to a measurement method of the plume divergence angle of the gasification product after ignition of a solid propellant, which comprises the following steps: acquiring a background image before ignition of a solid propellant and a gasification product expansion motion diagram in the ignition process; comparing the background image with the expansion motion diagram of the gasification product to obtain a gasification product image; solving radial distribution graphs of the radiant illuminance on N sections of the gasification product image; determining the maximum illuminance value on each section, and calculating the position of 98% of the maximum illuminance value on each section; and (3) linearly regressing the positions of all 98% of the maximum illuminance values by adopting a least square method, calculating the slope of a regression line, and calculating the plume divergence angle of the gasification product according to the slope of the regression line. The plume divergence angle measuring method provided by the invention ensures the measuring efficiency and high measuring precision.
Description
Technical Field
The invention belongs to the field of measurement of a plume divergence angle of a gasification product of a thruster, and particularly relates to a measurement method of the plume divergence angle of the gasification product after ignition of a solid propellant.
Background
The solid-gas conversion process is an indispensable process for providing a propeller of a solid propellant, and is also a precondition for ensuring the thrust generated by the subsequent electromagnetic acceleration. Properties of the gas product, including ionization degree, temperature, initial velocity and divergence angle, will be closely related to electromagnetic acceleration, ultimately affecting the propulsion performance of the propeller. Plume divergence angle is an important parameter that determines propeller efficiency. It represents the ratio of the momentum perpendicular to the axis to the kinetic energy parallel to the axis. If the divergence angle of the gas product is large, the plume divergence angle is expected to be large after electromagnetic acceleration, and the propellant utilization rate and efficiency are low.
The electric propeller mainly uses the faraday Li Tanzhen and the spectrum to measure the divergence angle of the jet plume. Both methods are suitable for measuring plumes away from the outlet, otherwise the probe and fiber would overheat from ion bombardment. Furthermore, they are both invasive measurement methods, and the movement of the probe in the plume region inevitably affects the plumes in both methods. The solid-gas conversion process of the solid propellant occurs only in a very small area around the solid propellant surface, which can be greatly affected by the expansion motion of the solid propellant if both the probe and spectroscopic methods are used, and the plume impingement can cause the probe and fiber optic probe to fail. Furthermore, probes and spectroscopic methods have long acquisition times, typically for steady state plume measurements, and are not suitable for transient rapid plume measurements.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for rapidly acquiring and measuring plume divergence angle of a gasification product of a solid propellant based on a method combining a high-speed camera and image processing in the solid-gas conversion process after the solid propellant is ignited by laser.
The invention provides a method for measuring the plume divergence angle of a gasification product after ignition of a solid propellant, which comprises the following steps:
s100, obtaining a background image before ignition of the solid propellant and a gasification product expansion motion diagram in the ignition process, wherein the shooting directions of the background image and the gasification product expansion motion diagram are consistent and mutually perpendicular to the axis of an ignition part of the solid propellant;
s200, comparing the gray values of the background image and the gasification product expansion motion diagram, determining the plume boundary of the gasification product expansion motion diagram, and dividing the gasification product part in the gasification product expansion motion diagram to obtain a gasification product image;
s300, acquiring the two-dimensional radiation illuminance distribution condition of the gasification product image, and solving the radiation illuminance radial distribution map on N sections of the gasification product image according to the two-dimensional radiation illuminance distribution condition of the gasification product image;
s400, determining the maximum illuminance value of each section according to the radial distribution diagram of the illuminance of the radiation on the N sections, and calculating the position of 98% of the maximum illuminance value of each section;
s500, carrying out linear regression on the positions of all 98% of the maximum illuminance values by adopting a least square method, calculating the slope of a regression line, and calculating the plume divergence angle of the gasification product according to the slope of the regression line.
Still further, the acquiring the background image before ignition of the solid propellant and the expansion motion map of the gasification product during ignition comprises:
and determining the exposure time of the high-speed camera according to the laser pulse width time of the ignition laser, wherein the exposure time of the high-speed camera is less than one thousandth of the laser pulse width time.
Further, according to the two-dimensional radiation illuminance distribution condition of the gasification product image, solving the radiation illuminance radial distribution map on the N sections of the gasification product image comprises:
establishing a coordinate point radiation illuminance solving model:
wherein P (x) 0 -1,0,Z 0 ) Is the midpoint (x) 0 -1,0,Z 0 ) Is a luminance value of (a);
is a pixel point (x) 0 -1，z 0 ) Illuminance value of +.>
Is a pixel point (x) 0 ，z 0 ) Is a luminance value of (a);
and solving an illuminance value corresponding to each point on the gasification product image by using a coordinate point illuminance solution model to obtain a radial illuminance distribution map of the illuminance of the gas product.
Further, the linear regression of the positions of all 98% of the maximum illuminance values using the least squares method includes:
dividing the radial distribution map of the radiation illuminance into an upper radial distribution map of the radiation illuminance and a lower radial distribution map of the radiation illuminance by taking the axis of the ignition part of the solid propellant as a dividing line, adopting a least square method to carry out linear regression on the positions of all 98% of the maximum illuminance values of the radial distribution map of the upper radiation illuminance, carrying out linear regression on the positions of all 98% of the maximum illuminance values of the radial distribution map of the lower radiation illuminance, and calculating the coordinates of points corresponding to the 98% of the maximum illuminance values;
the coordinate calculation model is as follows:
Z sumj ≤98％Z s ≤Z sum(j+1) #
wherein r is 98％ Is the coordinates of the point corresponding to 98% of the maximum illuminance value, Z s Is the maximum illumination value of the current interface, Z sumj Is the accumulated illumination value from the 1 st point to the j th point, Z sum(j+1) Is the accumulated luminance value from the 1 st point to the j+1st point, l is the actual length corresponding to a single pixel point, and the minimum distance between adjacent points in the radial luminance distribution map.
Still further, calculating the plume divergence angle of the gasification product includes:
establishing a plume divergence angle calculation model:
α＝tan -1 |k′|+tan -1 |k′|#(4)
where α is the divergence angle and k' and k "are the slopes of the two regression lines, respectively.
Further, comparing gray scale values of the background image and the gasification product expansion motion map, determining a plume boundary of the gasification product expansion motion map comprises:
and taking the maximum gray value in the background image as background gray, regarding the pixel point position with the gray value larger than the background gray after the gray processing of the expansion motion diagram of the vaporization product as the generation of the vaporization product, otherwise, regarding that the position is not generated by the vaporization product, thereby determining the plume boundary of the vaporization product.
The plume divergence angle measuring method has the advantages that equipment components are not required to invade the thruster, normal performance of the thruster is not affected, transient and rapid plume measurement is carried out on the ignition end of the thruster, the method is not limited to steady-state plume divergence angle measurement, the measuring range is improved, meanwhile, the method ensures measuring efficiency and high measuring precision, in addition, the plume divergence angle of a gasification product can be obtained by matching with image processing and calculation only by installing a high-speed camera on the side face of the thruster, the measuring cost is low, and the efficiency is high.
Drawings
FIG. 1 is a flow chart of a measurement method according to an embodiment of the invention;
FIG. 2 is a graph showing expansion movement of gasification products after ignition of a solid propellant by a laser in an embodiment of the present invention;
FIG. 3 is a schematic cross-sectional view of a gasification product according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; the device can be mechanically connected, electrically connected, physically connected or wirelessly connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.
As shown in fig. 1, the invention provides a method for measuring the plume divergence angle of gasification products after ignition of a solid propellant, which comprises the following steps:
s100, obtaining a background image before ignition of the solid propellant and a gasification product expansion motion diagram in the ignition process, wherein the shooting directions of the background image and the gasification product expansion motion diagram are consistent and mutually perpendicular to the axis of an ignition part of the solid propellant;
s100 may specifically include:
s101, determining the exposure time of the high-speed camera according to the laser pulse width time of the ignition laser.
The exposure time of the high speed camera should be much smaller than the laser pulse width time of the ignition laser while the exposure time should be as small as possible in order to achieve transient measurements of the gasification product plume, in order to obtain as much gasification product expansion motion map as possible within one laser pulse width time. Through data analysis, the high speed camera exposure time tb is preferably less than one thousandth of the laser pulse width time tl.
S102, determining the placement position of the high-speed camera, installing and adjusting the focal length, and ensuring that the focal point is focused on a target point (the laser spot position in FIG. 3) of the reaction between the laser and the surface of the solid propellant.
As shown in fig. 3, the high-speed camera should be placed on the side of the solid propellant, the central axis of the lens of the high-speed camera is on the same plane with the central axis of the laser spot on the solid propellant, and the former and the latter are perpendicular to each other. The vertical distance between the camera lens and the laser spot is L.
S103, taking a photo before laser ignition as a background image, and acquiring the intensity of background light so as to remove the influence of background interference light by subsequent normalization; meanwhile, the position of the camera is kept unchanged, a picture of a reference object with a standard size is shot, and a proportional scale relation between the picture size and the actual size is established.
The influence of light cannot be completely isolated in the measurement process, so that the background light needs to be processed. Recording a background image by photographing, assuming that the background gray maximum value of the background image is H 0 . At the same time, for the purpose of conveniently calculating and establishing the motion coordinates of the gasification product, the actual length L is known 0 Taking pictures of the reference object of (2), assuming that the pixel length in the picture is X 0 (i.e. X 0 A pixel point), at this time, the scale of the picture and the actual size is 1: l (L) 0 /X 0 。
S104, laser ignition of the solid propellant, and acquisition of a series of expansion motion diagrams of the gasified products after laser ablation of the propellant by using a high-speed camera.
Based on the parameters set in the previous step, the high speed camera can acquire a series of gasification product expansion motion maps as shown in fig. 2.
S200, comparing the gray values of the background image and the gasification product expansion motion diagram, determining the plume boundary of the gasification product expansion motion diagram, and dividing the gasification product part in the gasification product expansion motion diagram to obtain a gasification product image;
s200 may specifically include:
and determining a gasification product boundary, dividing a gasification product expansion motion diagram, and establishing a unified coordinate system.
The background gray maximum value H obtained according to S103 0 The gray value of the expansion motion diagram of the gasification product after gray processing is larger than H 0 And otherwise, determining the plume boundary of the gasification product, dividing the image of the expansion motion diagram of the original gasification product, removing the area without the gasification product, and only reserving the effective gray area to obtain the gasification product image. And establishing a unified orthogonal coordinate system for the gasification product image by taking the laser spot as an origin of coordinates, wherein the unit length of the coordinate axis is the size of a single pixel point.
S300, acquiring the two-dimensional radiation illuminance distribution condition of the gasification product image, and solving the radiation illuminance radial distribution map on N sections of the gasification product image according to the two-dimensional radiation illuminance distribution condition of the gasification product image;
s300 may specifically include:
s301, performing RGB image processing on the gasified product image, and respectively calculating gray values H of different pixel points in the gasified product image under red/green/blue three channels r /H g /H b Further calculating the illumination value Z of each pixel point, and obtaining the two-dimensional radiation illumination distribution condition of the gasification product image.
Each color can be visually synthesized from three colors of red, blue and green in different proportions, and an RGB image is essentially a three-dimensional matrix, i.e., (R, G, B) triplet two-dimensional matrix, where each pixel is a triplet of values corresponding to the R, G, B component of the RGB image at a particular spatial location. According to the OpenCV software library, matlab or Python can be adopted to directly read an image, so as to obtain the intensities of the image under red, green and blue three channels respectively, and the intensities under RGB three channels of a certain pixel point are assumed to be I respectively r ，I g ，I b . At this time, the corresponding gray value H under the red, green and blue three channels r ，H g ，H b Calculated by the formulas (1), (2) and (3), namely
Where pi is the circumference ratio, μ is the photoelectric conversion coefficient of the camera, η is the conversion coefficient between the gray value and the camera current, a is the entrance pupil aperture, f' is the image Fang Jiaoju, k is the transmissionThe light rate, Y is the spectral response characteristic function of different channels, l is the actual length corresponding to a single pixel point in the corresponding image, l=x 0 /L 0 。
When the gray value of a pixel under RGB three channels is known, the irradiance Z of the pixel can be calculated according to the formula (4), namely
The method is adopted to calculate the radiation illuminance value of each pixel point, so that the irradiation intensity two-dimensional distribution map of the gasification product image can be obtained.
According to the invention, the obtained expansion motion diagram of the gasification product is preprocessed, the RGB channel of the gasification product diagram is firstly converted into the gray value, and then the corresponding illumination value of the image is calculated according to the gray value, so that the accuracy of the obtained illumination value can be improved, and the plume divergence angle measurement accuracy is finally improved.
S302, solving a radial distribution diagram of the radiation illuminance of the gasification product according to the two-dimensional distribution situation of the radiation intensity of the gasification product image.
If the solid propellant is heated uniformly, the gasification products will be randomly dispersed around, and the gasification products can be considered to be column symmetric. When the gasification product is photographed from the side of the thruster, the obtained image radiation illuminance is the result of the projection of the illuminated columnar gasification product on the x-z plane, as shown in fig. 1. Therefore, the pixel point radiation illuminance on the image is the superposition of a plurality of pixels on the chord of the circular section of the columnar gasification product and is at the same axial position with the selected pixel point, and the corresponding relationship can be expressed as shown in the formula (5), namely
Wherein Z is (x,y) Is the irradiance, P, of the pixel point (x, z) in the image yi Is the irradiance corresponding to the midpoint (x, y, z) of the gasification product,
is the distance between the spatial point i (x, y, z) and the camera. When the distance between the camera and the axis of the gasification product is far greater than the length and the section radius of the gasification product, the distance between any pixel point of the gasification product in the image and the camera is considered to be equal, and the distance between the camera and the axis of the gasification product is equal to L. Thereby, the formula (5) can be converted into the formula (6).
When the laser is fired, the laser will react with the solid propellant, which begins with the laser spot to produce a vaporized product. The gasification product gradually expands outwards and spreads, which has a column-symmetrical structure. Therefore, for a circular cross section of any one gasification product, the pixels on the same circumference have the same illuminance value. As shown in FIG. 3, in the axial direction Z 1 The cross section of the location is exemplified by the column symmetry characteristics of the gasification product, thus point A 1 And A 1 ’，A 2 And A 2 ’，A 3 And A 3 ' have the same illuminance value. Thus segment A 1 A 4 The superposition of the illumination of the pixel points is equivalent to A 1 ’A 4 Superposition of pixel illumination between line segments. Let chord A 1 B has a projection point (x) 0 ，z 0 ) The illuminance therebetween at this time satisfies expression (7)
Wherein,,
is a pixel point (x) 0 ，z 0 ) Illuminance value of +.>
Is chord A 1 And B, the sum of illumination values corresponding to all points on the display screen.
As can be seen from the above expression (7), the pixel point (x 0 -1，z 0 ) The illuminance value expression (8) is
Wherein,,
is a pixel point (x) 0 -1，z 0 ) Is the luminance value of P (x) 0 -1,0,Z 0 ) Is the midpoint (x) 0 -1,0,Z 0 ) Is a luminance value of (a).
When the illuminance value of each pixel point in the image is known, the illuminance value of any point in the gasification product can be obtained, and the calculation formula (9) is
Therefore, the line segment A can be obtained by using the formula (9) 1 The radial illuminance distribution of the gas product is obtained by the illuminance value corresponding to each point on' 0.
S400, determining the maximum illuminance value of each section according to the radial distribution diagram of the illuminance of the radiation on the N sections, and calculating the position of 98% of the maximum illuminance value of each section;
s400 may specifically include:
s401, selecting N sections in the image according to measurement requirements, and respectively calculating radial illuminance distribution of the spatial gas products corresponding to different sections.
The gasification product of the solid propellant can be divided into numerous sections, where N sections (N being a positive integer) are selected, i.e. Z1 is selected to be different values, and subsequent sampling of the sections is averaged to improve the accuracy of the measurement.
Although the gasification product should theoretically satisfy columnar distribution, the gasification product is inevitably disturbed by the outside in the experiment, so that the image profile of the gasification product will slightly fluctuate, and a smooth curve is not completely formed. Therefore, if the radial distribution results of the illuminance of the gasification product are solved by respectively adopting the illuminance of the upper and lower images of the Z axis (the axis of the ignition part of the solid propellant), the radial distribution results of the illuminance of the gasification product by adopting the illuminance of the upper image of the Z axis are called as upper radiation illuminance radial distribution, and the radial distribution results of the illuminance of the gasification product by adopting the illuminance of the lower image of the Z axis are called as lower radiation illuminance radial distribution. The invention adopts the radial distribution of the upper and lower radiation illuminance to calculate, which can greatly reduce the error and improve the measurement accuracy. All subsequent radial distribution solutions involve both upper and lower radial distribution cases.
S402, determining the maximum illumination value Zs of the current section according to the spatial radial illumination distribution conditions of different sections, and then calculating the position of 98% Zs at the radial distribution position.
The gasification product has a column symmetry characteristic, and typically the maximum illumination value Zs of the current cross-section is equal to half the illumination value of the intersection of the projection of this cross-section in the image with the central axis (i.e. the Z-axis). It should be noted that, since the minimum unit of the image is a pixel, the minimum distance between adjacent points in the radial illuminance distribution map is the actual length corresponding to a single pixel point, i.e., l=x0/L0 defined above.
Calculating the position corresponding to 98% of the maximum illuminance value, sequentially accumulating the illuminance values of each point along the radial direction from the round point of the circular section as the starting point, obtaining the accumulated illuminance value Zsum from the 1 st point to the j th point by each accumulation, finding two accumulated illuminance values closest to the 98% of the maximum illuminance value, obtaining the positions of the two points corresponding to the two illuminance values, assuming the j and j+1 th points, and calculating the coordinate r of the point corresponding to the 98% of the maximum illuminance value by a linear interpolation method (formula 11) 98％ 。
Z sumj ≤98％Z s ≤Z sum(j+1) #(10)
Wherein r is 98％ Is the coordinates of the point corresponding to 98% of the maximum illuminance value, Z s Is the maximum illumination value of the current interface, Z sumj Is the accumulated illumination value from the 1 st point to the j th point, Z sum(j+1) Is the accumulated luminance value from the 1 st point to the j+1st point, l is the actual length corresponding to a single pixel point, and the minimum distance between adjacent points in the radial luminance distribution map.
Based on the method, for the two conditions of up/down radial distribution, the coordinates of the points corresponding to the up and down 98% maximum illuminance values can be obtained, and the up and down points are defined as Z' s 98％ (x’ 98％ ，z’ 98％ ) And Z "s 98％ (x” 98％ ，z” 98％ ). Meanwhile, radial distribution of different sections is solved, and a series of 98% maximum illuminance value points can be obtained.
S500, carrying out linear regression on the positions of all 98% of the maximum illuminance values by adopting a least square method, calculating the slope of a regression line, and calculating the plume divergence angle of the gasification product according to the slope of the regression line.
S500 may specifically include:
s501, linearly regressing all 98% maximum illuminance value points of the upper part of the Z axis by taking the Z axis as a boundary, calculating the slope of a regression line, and marking as k'; similarly, linear regression was performed on all 98% maximum illuminance value points in the lower part of the Z axis, and the slope of the regression line was calculated and recorded as k ".
And the least square method is adopted to carry out linear regression on all the 98% maximum illumination value points, so that the influence of experimental system errors and accidental errors on the measurement of the divergence angle of the gasification product can be reduced as much as possible.
S502, calculating the plume divergence angle alpha of the gasification product according to the slope of the upper and lower regression lines.
The plume divergence angle alpha of the gasification product is calculated according to equation (12), i.e
α＝tan -1 |k′|+tan -1 |k′|#(12)
Where α is the divergence angle and k' and k "are the slopes of the two regression lines, respectively.
According to the method, two corresponding upper and lower 98% maximum illumination points are found in one section, linear regression is then carried out, the plume divergence angle is calculated according to the slope of a regression line, and compared with the conventional method of directly finding one 95% maximum illumination point in one section for calculation, the method has more accurate and reliable measurement results for transient plume divergence angle measurement of a solid propellant gasification product.
What is not described in detail in this specification is prior art known to those skilled in the art.
Claims (6)
1. A method for measuring the plume divergence angle of a gasification product after ignition of a solid propellant, comprising the steps of:
s100, obtaining a background image before ignition of the solid propellant and a gasification product expansion motion diagram in the ignition process, wherein the shooting directions of the background image and the gasification product expansion motion diagram are consistent and mutually perpendicular to the axis of an ignition part of the solid propellant;
s200, comparing the gray values of the background image and the gasification product expansion motion diagram, determining the plume boundary of the gasification product expansion motion diagram, and dividing the gasification product part in the gasification product expansion motion diagram to obtain a gasification product image;
s300, acquiring the two-dimensional radiation illuminance distribution condition of the gasification product image, and solving the radiation illuminance radial distribution map on N sections of the gasification product image according to the two-dimensional radiation illuminance distribution condition of the gasification product image;
s400, determining the maximum illuminance value of each section according to the radial distribution diagram of the illuminance of the radiation on the N sections, and calculating the position of 98% of the maximum illuminance value of each section;
s500, carrying out linear regression on the positions of all 98% of the maximum illuminance values by adopting a least square method, calculating the slope of a regression line, and calculating the plume divergence angle of the gasification product according to the slope of the regression line.
2. The method for measuring the plume divergence angle of the gasification product after ignition of the solid propellant as recited in claim 1, wherein the acquiring the background image of the solid propellant before ignition and the expansion motion map of the gasification product during ignition comprises:
and determining the exposure time of the high-speed camera according to the laser pulse width time of the ignition laser, wherein the exposure time of the high-speed camera is less than one thousandth of the laser pulse width time.
3. The method of measuring the plume divergence angle of a gasification product after ignition of a solid propellant as set forth in claim 1, wherein solving the radial distribution map of the illuminance on N cross sections of the gasification product image based on the two-dimensional illuminance distribution of the gasification product image comprises:
establishing a coordinate point radiation illuminance solving model:
wherein P (x) 0 -1，0，Z 0 ) Is the midpoint (x) 0 -1，0，Z 0 ) Is a luminance value of (a);
is a pixel point (x) 0 -1，z 0 ) Illuminance value of +.>
Is a pixel point (x) 0 ，z 0 ) Is a luminance value of (a);
and solving an illuminance value corresponding to each point on the gasification product image by using a coordinate point illuminance solution model to obtain a radial illuminance distribution map of the illuminance of the gas product.
4. The method of measuring the plume divergence angle of a gasification product after ignition of a solid propellant as recited in claim 1, wherein said employing a least squares method to linearly regress the locations of all 98% of the maximum illuminance values comprises:
igniting the radial distribution pattern of the irradiance with solid propellantThe bit axis is a dividing line and is divided into an upper radiation illuminance radial distribution diagram and a lower radiation illuminance radial distribution diagram, a least square method is adopted to carry out linear regression on the positions of all 98% of the maximum illuminance values of the upper radiation illuminance radial distribution diagram, and the positions of all 98% of the maximum illuminance values of the lower radiation illuminance radial distribution diagramFeeding in Linear regression of rowsCalculating coordinates of a point corresponding to a 98% maximum illuminance value;
the coordinate calculation model is as follows:
Z sumj ≤98％Z s ≤Z sum(j+1)
wherein r is 98％ Is the coordinates of the point corresponding to 98% of the maximum illuminance value, Z s Is the maximum illumination value of the current interface, Z sumj Is the accumulated illumination value from the 1 st point to the j th point, Z sum(j+1) Is the accumulated luminance value from the 1 st point to the j+1st point, l is the actual length corresponding to a single pixel point, and the minimum distance between adjacent points in the radial luminance distribution map.
5. The method of measuring the plume divergence angle of a gasification product after ignition of a solid propellant of claim 1, wherein calculating the plume divergence angle of the gasification product comprises:
establishing a plume divergence angle calculation model:
α＝tan -1 |k′|+tan -1 |k′|
where α is the divergence angle and k' and k "are the slopes of the two regression lines, respectively.
6. The method of measuring a plume divergence angle of a gasification product after ignition of a solid propellant as recited in claim 1, wherein comparing gray values of the background image and the gasification product expansion motion map to determine a plume boundary of the gasification product expansion motion map comprises:
and taking the maximum gray value in the background image as background gray, regarding the pixel point position with the gray value larger than the background gray after the gray processing of the expansion motion diagram of the vaporization product as the generation of the vaporization product, otherwise, regarding that the position is not generated by the vaporization product, thereby determining the plume boundary of the vaporization product.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310073468.2A CN116044616A (en) | 2023-01-13 | 2023-01-13 | Method for measuring plume divergence angle of gasification product after ignition of solid propellant |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310073468.2A CN116044616A (en) | 2023-01-13 | 2023-01-13 | Method for measuring plume divergence angle of gasification product after ignition of solid propellant |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116044616A true CN116044616A (en) | 2023-05-02 |
Family
ID=86129359
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310073468.2A Pending CN116044616A (en) | 2023-01-13 | 2023-01-13 | Method for measuring plume divergence angle of gasification product after ignition of solid propellant |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116044616A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117647682A (en) * | 2023-10-30 | 2024-03-05 | 遨天科技(北京)有限公司 | Electric thruster life prediction method and device |
-
2023
- 2023-01-13 CN CN202310073468.2A patent/CN116044616A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117647682A (en) * | 2023-10-30 | 2024-03-05 | 遨天科技(北京)有限公司 | Electric thruster life prediction method and device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105606222A (en) | Flame three-dimensional temperature field measurement imaging device, measuring device and measuring method | |
| CN109443253B (en) | Laser coaxiality detection device and method | |
| CN116044616A (en) | Method for measuring plume divergence angle of gasification product after ignition of solid propellant | |
| CN112634373B (en) | Visual measurement system dynamic correction method based on zero-expansion ceramic calibration plate | |
| CN111854622B (en) | Large-field-of-view optical dynamic deformation measurement method | |
| CN109916531B (en) | Semitransparent flame three-dimensional temperature field measuring method based on light field refocusing | |
| JP2008267843A (en) | Tunnel face surface measuring system | |
| CN115205466B (en) | Three-dimensional reconstruction method and system for power transmission channel based on structured light | |
| CN114838668B (en) | Tunnel displacement monitoring method and system | |
| CN111458051A (en) | Three-dimensional temperature field measuring system and method based on pixel-level spectral photodetector | |
| Bartels et al. | Mapping metabolites from rough terrain: laser ablation electrospray ionization on non-flat samples | |
| CN110827360B (en) | Photometric stereo measurement system and method for calibrating light source direction thereof | |
| BRPI0907048B1 (en) | method for measuring the temperature of a sheet material, and, temperature measurement system | |
| CN114152210A (en) | Synchronous measurement system for surface deformation and pressure distribution of rotating part | |
| JP2014153149A (en) | Shape measurement device, structure manufacturing system, shape measurement method and program | |
| Yuan et al. | A precise calibration method for line scan cameras | |
| CN111928774A (en) | Target tracking, positioning and measuring method based on combination of camera and range finder | |
| CN111899344A (en) | Flame emission tomography reconstruction device and method based on camera array | |
| CN104574369B (en) | The fuzzy depth acquisition methods of global diffusion based on thermal diffusion | |
| CN114241059B (en) | Synchronous calibration method for camera and light source in photometric stereo vision system | |
| CN110706292B (en) | Two-dimensional workbench error self-calibration method based on machine vision | |
| CN112229943B (en) | Single-camera-based spray flame synchronous observation method and system | |
| CN111623960B (en) | Method and device for measuring optical axis of structured light module | |
| Hamrouni et al. | A new method for stereo-cameras self-calibration in Scheimpflug condition | |
| Du et al. | Research on Calibration Method of off-axis Closed-loop Detection System for Multi-target Spectral Telescope |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |