A solid propellant high-pressure combustion flow field testing device and method based on particle image velocimetry technology

Abstract

A kind of solid propellant high-pressure combustion flow field testing device and method based on particle image velocimetry technique, the high-pressure combustion flow field testing device includes visual high-pressure combustion chamber, solid propellant placement platform, ignition system, smoke blowing and filtering system, double frame high frequency shooting system, high frequency laser system;Al2O3 particle generated by solid propellant combustion is used as tracer particle, the problem that tracer particle is difficult to accurately inject in high-pressure environment combustion flow field is solved;Narrow band filter is used to filter strong background radiation caused by solid propellant combustion, and the motion trajectory image of tracer particle is obtained;Through smoke blowing and filtering system, the removal of Al2O3 particle generated by solid propellant combustion is realized, and the influence on observation field of view and sheet light source is avoided.The present application is convenient to adjust, has good repeatability, low cost, is convenient to disassemble and maintain, has higher engineering applicability and experimental reliability, and can be suitable for high-pressure combustion flow field test experiment of any aluminum-containing solid propellant.

Description

Technical Field

[0001] This invention relates to the field of high-pressure combustion diagnostics for solid propellants, and particularly to a device and method for non-contact, full-field, quantitative measurement of the transient flow field of gaseous products from solid propellant combustion under high pressure. Background Technology

[0002] Solid propellant combustion is a high-temperature, high-pressure process involving intense chemical reactions, multiphase coupled flow, and heat transfer. The resulting high-pressure transient flow field characteristics are crucial for studying phenomena such as engine ballistic performance, combustion stability, particle mixing, and erosive combustion. However, solid propellant combustion in a high-pressure environment is a rapid transient process on the order of milliseconds or even microseconds. Parameters in the flow field, such as pressure, temperature, velocity, and component concentration, change drastically within an extremely short time. Therefore, a testing system with extremely high time resolution and response frequency is required to capture the true transient structure of the flow field, rather than a time-averaged result. Furthermore, the intense and non-uniform background radiation during combustion also poses a significant challenge to flow field measurement. This is because the strong background radiation causes overexposure during imaging, severely reducing the observability of tracer particles in the combustion flame region, or even making them unobservable. Consequently, it becomes impossible to accurately identify and locate the particle center, ultimately leading to errors or failures in velocity vector calculations.

[0003] Currently, traditional contact probe measurement techniques are prone to ablation and interference with the flow field, making accurate measurement of flow field distribution difficult. Single-point measurements based on laser Doppler velocimeters are also unsuitable for testing high-pressure combustion flow fields of solid propellants due to low testing efficiency. Conventional particle image velocimetry, with its non-contact, instantaneous, full-field measurement capabilities, overcomes the limitations of traditional point measurement techniques, greatly advancing the understanding and research of complex flow phenomena. Currently, in gas or liquid flow field observation experiments, because the flow process is transparent, it is necessary to add tracer particles to the fluid using a fluid tracer particle generator to reflect changes in the flow field. The injection of tracer particles in high-pressure combustion flow field testing experiments of solid propellants is extremely difficult. The core challenges are: 1. The injection technology is challenging, requiring precise positioning and penetration of the combustion gas flow under the closed high-pressure conditions of the combustion chamber. The injection probe faces the risk of ablation and damage, and the injection probe can severely disturb the local flow field structure, change the thermodynamic conditions near the combustion surface, and even affect the combustion rate; 2. The high-pressure environment places extremely high demands on the sealing and pressure resistance of the injection system. Even minor leaks or structural deformations can interfere with the stability of particle delivery; 3. In high-temperature and high-pressure environments, tracer particles may melt and agglomerate, reducing their airflow following ability and tracer capability; 4. The fixed formulation ratio of practical solid propellants makes it difficult to directly add tracer particles to the solid propellant body, resulting in inaccurate characterization of the solid propellant combustion flow field. In addition, the extremely strong continuous spectral background radiation will completely overwhelm the particle scattering signal, resulting in an extremely low signal-to-noise ratio, which in turn makes it impossible for particle image motion algorithms to accurately identify particles; high-concentration particle clouds will cause severe absorption and scattering of the laser sheet light source, causing the laser energy to decay rapidly during the process of penetrating the flow field, resulting in the flow field not being illuminated and forming a measurement blind zone.

[0004] Therefore, developing a particle image velocity testing method and its application that can effectively overcome interference from high-voltage environments, achieve high signal-to-noise ratio, and provide full-field quantitative measurement has become an urgent technical need in this field. Summary of the Invention

[0005] To address at least one technical problem mentioned above and in other aspects of the prior art, this invention provides a device and method for testing the high-pressure combustion flow field of solid propellants based on particle image velocimetry technology. This device features a high signal-to-noise ratio and strong anti-interference capability, and can accurately test the combustion flow field distribution of solid propellants under high-pressure conditions. The device is ingeniously designed and has a simple structure, exhibiting good compatibility and adaptability. It can be widely applied to high-pressure combustion experiments of various aluminum-containing solid propellant grains, achieving high-resolution and quantitative measurement of the combustion flow field, and providing crucial data support for combustion mechanism research, engine performance optimization, and unstable combustion suppression.

[0006] The technical solution of this invention is achieved through the following measures:

[0007] A solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology includes a visualized high-pressure combustion chamber, an intake and exhaust control system, a solid propellant placement platform, an ignition system, a smoke purging and filtration system, a dual-frame high-frequency imaging system, a high-frequency laser system, a synchronous controller, and a data acquisition and processing system. The visualized high-pressure combustion chamber provides a sealed high-pressure environment. The intake and exhaust control system remotely controls the injection and discharge of gas inside the visualized high-pressure combustion chamber. The solid propellant placement platform holds the solid propellant. The ignition system ignites the solid propellant. The smoke purging and filtration system consists of a smoke purging device and a flue gas circulation device. The system comprises a smoke removal device, used to generate a stable airflow carrying Al2O3 particles from the solid propellant combustion, which are then trapped by the smoke removal device; a dual-frame high-frequency imaging system, consisting of a dual-frame high-frequency camera, camera lens, and narrowband filter, to capture images of the illuminated Al2O3 particles for particle tracking image analysis; a high-frequency laser system to generate a sheet light source to illuminate the Al2O3 particles; a synchronization controller to synchronize the operation of the dual-frame high-frequency camera and the high-frequency laser system; and a data acquisition and processing system to acquire pressure and temperature parameters inside the container, process the Al2O3 particle images, and obtain the high-pressure combustion flow field of the solid propellant; the solid propellant must contain aluminum particles.

[0008] According to an embodiment of this disclosure, the solid propellant placement platform and the flue gas circulation device are placed on top of the smoke purging device, and the lower part of the flue gas circulation device is fixed to the smoke purging device with a fixing pin.

[0009] According to embodiments of this disclosure, the upper part of the smoke purging device is a porous flow equalizer used to generate a continuous and stable upward airflow.

[0010] According to the embodiments of this disclosure, four vertically distributed flue gas flow observation windows are provided in the middle of the flue gas flow device, and their axial center positions are consistent with the axial center positions of the visualization high-pressure combustion chamber window. There is a certain space between the upper part of the flue gas flow device and the upper part of the visualization high-pressure combustion chamber for the change of the flow direction of the mixed airflow.

[0011] According to embodiments of this disclosure, the airflow generated by the smoke purging device is mixed with the airflow of solid propellant combustion products and then transported vertically upward through the flue gas duct, and subsequently returned through an annular channel formed by the outside of the flue gas circulation device and the inside of the visible high-pressure combustion chamber.

[0012] According to embodiments of this disclosure, the smoke removal device is placed on the outer protrusion of the flue gas circulation device and the protrusion inside the visualization high-pressure combustion chamber, and is higher than the visualization window, in order to remove Al2O3 particles in the mixed gas flow during the recirculation process and prevent obstruction of the observation field.

[0013] According to embodiments of this disclosure, the laser used in the above-mentioned high-frequency laser system generates a 527nm wavelength light source. After the laser beam passes through a beam shaper, it forms a thin and bright sheet light source, which penetrates a high-pressure resistant sapphire lens and illuminates the cross section of the flow field to be measured.

[0014] According to an embodiment of this disclosure, a narrow-band filter is installed in front of the camera lens in the above-mentioned dual-frame high-frequency imaging system to filter out the strong background light source during the combustion of solid propellant. It is arranged at 90° with the high-frequency laser system to vertically capture images illuminating the flow field interface, and the imaging frequency is not less than 6000Hz.

[0015] According to the solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology provided in this disclosure, high-pressure gas is introduced into the visualized high-pressure combustion chamber through an intake and exhaust control system, so that the pressure inside the visualized combustion chamber reaches the pressure value required for solid propellant combustion; the solid propellant is ignited using the aforementioned ignition system, and during the combustion process, the combustion products of the solid propellant are sprayed vertically upwards; a high-frequency dual-pulse laser source is generated using the aforementioned high-frequency laser system, and after beam shaping, a sheet light source is formed that penetrates a high-pressure resistant sapphire lens to illuminate the internal plane of the solid propellant combustion flow field; Al2O3 particles generated by the combustion of aluminum particles inherent in the solid propellant are used as tracer particles, and a dual-frame... A high-frequency imaging system captures images of tracer particles illuminated by a high-frequency laser system, obtaining images of tracer particles continuously illuminated by the laser. These images are then input into a data acquisition and processing system, where Tecplot software is used to plot and analyze the combustion flow field distribution of solid propellant under high pressure. A continuous and stable airflow is generated by the smoke purging device in the aforementioned smoke purging and filtration system to purge the combustion products of the solid propellant, causing them to move vertically upwards within the flue gas flow device. The airflow is redirected within the space reserved between the flue gas flow device and the upper part of the visualization high-pressure combustion chamber. When the mixed airflow flows back through the smoke removal device, Al2O3 particles are trapped, preventing obstruction of the visualization observation field and the laser sheet light source.

[0016] Install a high-pressure sapphire lens on the visualization window; install the igniter external connector, ignition wire winding connector, and smoke purging system bracket on the lower end cover of the combustion chamber; open the upper end cover of the combustion chamber to open the sealed high-pressure visualization combustion chamber; install the fan bracket for supporting the fan motor and fan blades on the smoke purging system bracket; place a gas buffer pipe on the fan bracket and secure it with fastening nuts; place a multi-hole flow equalizer above the gas buffer pipe to generate a continuous and stable airflow.

[0017] The ignition wire passes through the upper end of the solid propellant, placing the solid propellant in the middle of the ignition wire. The lower end of the solid propellant is clamped by a solid propellant clamp and placed in the middle of the porous flow equalizer, so that the solid propellant can appear in the middle of the observation field of view.

[0018] Place the flue gas flow device above the porous flow equalizer, keeping the observation window of the flue gas flow device aligned with the axis of the visualization window, and the protrusion inside the visualization high-pressure combustion chamber and the protrusion outside the flue gas flow device at the same level; use a fixing pin to fix it to the buffer pipe through the through hole in the base of the flue gas flow device to prevent the airflow from causing shaking.

[0019] The ignition wire is passed through the observation windows of the flue gas flow device on both sides and wound around the ignition wire winding post. The position of the ignition wire is adjusted to prevent it from contacting the flue gas flow device and causing a short circuit in the ignition circuit, thus preventing ignition. An annular porous filter is placed on the platform formed by the protrusion inside the high-pressure combustion chamber and the protrusion outside the flue gas flow device to trap Al2O3 particles in the mixed gas flow and prevent them from affecting the observation field of view. The camera lens is adjusted to enhance the light intake, and a real image of the solid propellant is taken. The length of its upper end face is used as the scale length to provide a basis for subsequent calculations. A narrow-band filter is installed at the front of the camera lens. The upper end cover of the combustion chamber is fixed to the high-pressure combustion chamber cavity with bolts to form a sealed space.

[0020] The visualization window corresponding to the dual-frame high-frequency imaging camera is arranged at a 90° angle to the visualization window corresponding to the high-frequency laser system. The high-frequency laser system generates a sheet light source that enters the high-pressure combustion chamber from the side of the combustion flame. The dual-frame high-frequency imaging camera is equipped with a camera lens and a narrow-band filter at its front end, and is arranged perpendicular to the sheet light source. A high-purity nitrogen cylinder is connected to the booster compressor via a low-pressure gas delivery pipeline. The high-pressure gas delivery pipeline, equipped with an intake solenoid valve, is connected to the booster compressor and the high-pressure combustion chamber cavity at both ends. An exhaust solenoid valve is installed in the exhaust pipe installed on the upper part of the high-pressure combustion chamber cavity. The booster compressor, intake solenoid valve, exhaust solenoid valve, and igniter external terminal wiring are all remotely controlled via a control panel.

[0021] A method for testing the high-pressure combustion flow field of solid propellants based on particle image velocimetry technology includes the following steps:

[0022] (1) Connect the control cables of the data acquisition and processing system, synchronous controller, dual-frame high-frequency camera and high-frequency laser system, and turn on the corresponding dual-frame high-frequency camera and high-frequency laser system control software on the data processing system.

[0023] (2) Cut out solid propellant blocks of a fixed size, and pass an ignition wire through the upper surface of the solid propellant block from the side, clamp the solid propellant block on the solid propellant placement platform, and place the solid propellant placement platform in the middle position of the porous flow equalizer in the smoke purge device.

[0024] (3) Place the flue gas flow device on the porous flow equalizer of the smoke purging device, rotate the flue gas flow device so that the four vertically distributed flue gas flow device observation windows correspond to the visual window axis of the visual high-pressure combustion chamber respectively, and fix them with fixing pins;

[0025] (4) Pass the excess ignition wire through the observation window in the middle of the flue gas flow device and wrap it around the ignition wire winding column of the ignition system. Adjust the position of the ignition wire to prevent it from contacting the flue gas flow device.

[0026] (5) Place the annular porous filter in the smoke removal device on the outer protrusion of the flue gas flow device and the protrusion in the visible high-pressure combustion chamber so that the Al2O3 particles in the circulating return gas are intercepted.

[0027] (6) Adjust the aperture of the dual-frame high-frequency camera, take real pictures of the solid propellant, and use the length of its upper end face as the scale length to provide a basis for subsequent flow field calculations;

[0028] (7) Sealed, visualized high-pressure combustion chamber;

[0029] (8) Close the exhaust solenoid valve, open the intake solenoid valve, open the high-purity nitrogen cylinder, start the booster, and repeatedly fill the interior of the visual high-pressure combustion chamber with high-purity nitrogen to 1MPa. Then open the exhaust solenoid valve to exhaust 3 times to make the visual high-pressure combustion chamber completely filled with high-purity nitrogen atmosphere.

[0030] (9) Close the exhaust solenoid valve, open the intake solenoid valve to charge the air so that the pressure inside the visible high-pressure combustion chamber is increased to the set value, and then close the intake solenoid valve.

[0031] (10) Activate the smoke purging device and continue for 1 minute to stabilize the gas flow inside the visible high-pressure combustion chamber;

[0032] (11) Turn on the high-frequency laser system to generate a high-frequency pulse plate light source, and adjust the angle, position and thickness of the plate light source so that the thin and bright plate light source can completely illuminate the area to be observed;

[0033] (12) Install the narrowband filter on the front of the lens of the dual-frame high-frequency camera;

[0034] (13) Set the output frequency of the high-frequency laser system and the shooting frequency parameters of the dual-frame high-frequency camera;

[0035] (14) Turn on the high-frequency laser system, ignite the solid propellant and press the dual-frame high-frequency camera shooting button at the same time to obtain the high-pressure combustion flow field image of the solid propellant.

[0036] (15) Open the exhaust solenoid valve to release the gas inside the visible high-pressure combustion chamber;

[0037] (16) To conduct experiments on multiple samples, steps (2)-(15) need to be repeated;

[0038] (17) Browse, analyze and eliminate problematic images, select the solid propellant high-pressure combustion flow field image to be processed, and input it into the dedicated software for particle image velocity measurement to obtain data information;

[0039] (18) Import the combustion flow data information obtained from the image into the Tecplot plotting software to draw the flow field cloud map and extract the specific parameters such as the corresponding curves.

[0040] In this invention, the Al2O3 particles generated from the combustion of aluminum particles within the solid propellant are excellent tracer particles and can be used as tracer particles for testing the combustion flow field of solid propellants. Based on this characteristic, particle image velocimetry technology can be introduced to test the combustion flow field of solid propellants. The gas released from the combustion of solid propellants is in a laminar flow state near the combustion surface. Particles escaping from the combustion surface have relatively good tracking ability, moving away from the combustion surface under the carrying effect of the airflow and rapidly transitioning to the turbulent combustion region.

[0041] In this invention, the light source signal scattered by the tracer particles illuminated by the 527nm wavelength light emitted by the laser is masked by the strong radiation signal from the combustion process. A narrow-band filter is installed at the front end of a dual-frame high-frequency imaging camera. This filter only allows the extremely narrow wavelength 527nm light emitted by the laser to enter the camera, while other wavelengths are blocked. In other words, only the 527nm laser signal is allowed to enter the camera, thus enabling the acquisition of images of the tracer particles and the identification of their positions. Furthermore, this invention generates circulating gas within a high-pressure visualization combustion chamber, flowing from bottom to top. An annular porous filter removes smoke particles generated by the combustion of solid propellant. Al2O3 particles are removed during the particle return path to avoid affecting the lateral sheet light source and the field of view. The sheet light source enters from the side of the combustion flame, rather than from the top, to prevent attenuation of the irradiated laser energy.

[0042] This invention provides a solid propellant high-pressure combustion flow field testing device and its method based on particle image velocimetry technology. By using Al2O3 particles generated by the combustion of solid propellant as tracer particles, the problem of accurate injection of tracer particles in high-pressure combustion flow fields is solved. A narrow-band filter is used to filter the strong background radiation from solid propellant combustion, acquiring images of the tracer particle trajectories, achieving non-invasive, full-domain quantitative measurement of the solid propellant high-pressure combustion flow field. By combining a smoke purging system, a flue gas circulation device, and a smoke removal system, the removal of Al2O3 particles from solid propellant combustion is achieved, avoiding interference with the observation field and the sheet light source. The entire device is easy to adjust, has good repeatability, low cost, and is convenient to disassemble and maintain. It possesses high engineering applicability and experimental reliability, and can be applied to high-pressure combustion flow field testing experiments of any aluminum-containing solid propellant. Attached Figure Description

[0043] These and / or other aspects and advantages of the present invention will become clearer and more readily understood from the following detailed description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

[0044] Figure 1 This is a schematic diagram illustrating the implementation of the solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology described in this invention.

[0045] Figure 2 To visualize the internal structure of the high-pressure combustion chamber;

[0046] Figure 3 This is a schematic diagram of the flue gas circulation device.

[0047] In the accompanying drawings, the meanings of the reference numerals are as follows:

[0048] 101 is the intake solenoid valve; 102 is the high-pressure gas delivery pipeline; 103 is the booster compressor; 104 is the high-purity nitrogen cylinder; 105 is the low-pressure gas delivery pipeline; 106 is the control panel; 107 is the exhaust solenoid valve; 108 is the exhaust pipeline;

[0049] 201 is the high-pressure combustion chamber cavity; 202 is the upper end cover of the combustion chamber; 203 is the visualization window; 204 is the high-pressure resistant sapphire lens; 205 is the lower end cover of the combustion chamber; 206 is the inner boss of the high-pressure visualization combustion chamber.

[0050] 301 is a sheet light source; 302 is a beam shaper; 303 is a light guide arm; 304 is a grating; 305 is a laser; 306 is a laser cooler;

[0051] 401 is the data processing system; 402 is the data acquisition system; 403 is the pressure sensor; 404 is the temperature sensor.

[0052] 501 is a synchronous controller;

[0053] 601 is the external connector of the igniter; 602 is the ignition wire winding connector; 603 is the ignition wire.

[0054] 701 is a dual-frame high-frequency shooting camera; 702 is a camera lens; 703 is a narrowband filter;

[0055] 801 is for solid propellant; 802 is for solid propellant clamping.

[0056] 901 is the smoke purging system bracket; 902 is the fan motor; 903 is the fan blade; 904 is the fan bracket; 905 is the fastening nut; 906 is the gas buffer pipe; 907 is the porous flow equalizer; 908 is the flue gas circulation device base; 909 is the fixing pin; 910 is the flue gas circulation device observation window; 911 is the flue gas circulation device external boss; 912 is the annular porous filter; 913 is the flue gas duct. Detailed Implementation

[0057] To make the objectives, technical solutions, and advantages of this embodiment clearer, the technical solutions will be described in more detail below with reference to specific embodiments and accompanying drawings.

[0058] In this embodiment, the appendix Figure 1 This is a schematic diagram of the working process of a solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology. It does not specify the position or layout of any particular component. (Attached) Figure 2 To visualize the sectional view of the high-pressure combustion chamber's internal structure, and for ease of description, the relative positions of the components are depicted according to the appendix to the instruction manual. Figure 2 The layout is described using a diagrammatic method, such as the positional relationships of front, back, top, bottom, left, and right, which are based on the instructions attached. Figure 2 The orientation of the layout is determined by the direction of the map.

[0059] In the description of this embodiment, unless otherwise explicitly limited, terms such as "setup," "installation," and "connection" should be interpreted broadly. Those skilled in the art can reasonably determine the specific meaning of the above terms in this embodiment in conjunction with the specific content of the technical solution.

[0060] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. The embodiments are described in detail below with reference to the accompanying drawings:

[0061] Appendix Figure 1This is a schematic diagram of an implementation of a solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to this embodiment. It includes a visualized high-pressure combustion chamber, an intake and exhaust control system, a solid propellant placement platform, an ignition system, a smoke purging and filtration system, a dual-frame high-frequency imaging system, a high-frequency laser system, a synchronous controller 501, and a data acquisition and processing system. Specifically, the installation method is as follows: a high-purity nitrogen cylinder 104 is connected to a booster compressor 103 via a low-pressure gas delivery pipeline 105; a high-pressure gas delivery pipeline 102, equipped with an intake solenoid valve 101, is connected at both ends to the booster compressor 103 and the high-pressure combustion chamber cavity 201, respectively; an exhaust solenoid valve 107 is installed in the exhaust pipeline 108 installed on the upper part of the high-pressure combustion chamber cavity 201; the booster compressor 103, intake solenoid valve 101, exhaust solenoid valve 107, and igniter external connector 601 are all remotely controlled via a control panel 106; the high-pressure combustion chamber cavity 201 and the upper part of the combustion chamber... The end cap 202 and the lower end cap 205 of the combustion chamber form a sealed container. Four mutually perpendicular viewing windows 203 in the middle are equipped with high-pressure resistant sapphire lenses 204. After the laser 305, placed above the laser cooler 306, is activated to generate a light source, it passes through the grating 304, the light guide arm 303, and the beam shaper 302 to the left to generate a sheet light source 301. The front end of the dual-frame frequency imaging camera 701 is equipped with a camera lens 702 and a narrow-band filter 703. The dual-frame frequency imaging camera 701 is arranged perpendicularly to the sheet light source 301 and is used to capture Al2O3 particles generated by the combustion of the illuminated solid propellant 801. The data acquisition system 402 acquires the environmental status signal inside the high-pressure combustion chamber cavity 201 through the pressure sensor 403 and the temperature sensor 404 and transmits it to the data processing system 401 for display. The data processing system 401 synchronously controls the start and stop of the dual-frame frequency imaging camera 701 and the laser 305 through the synchronization controller 501.

[0062] Appendix Figure 2This is a cross-sectional view of the internal structure of the high-pressure combustion chamber. The high-pressure combustion chamber cavity 201, together with the upper end cover 202 and the lower end cover 205, forms a closed container. A viewing window 203 is opened in the middle of the high-pressure combustion chamber cavity 201, and a high-pressure resistant sapphire lens 204 is installed on the viewing window 203. The ignition wire winding post 602 of the ignition system extends into the interior of the high-pressure combustion chamber, and the igniter terminal 601 is placed outside the lower end cover 205 of the combustion chamber. Four smoke purging system brackets 901 are installed on the lower end cover 205 of the combustion chamber. A fan bracket 904, which supports the fan motor 902 and the fan blades 903, is installed on the smoke purging system brackets 901. Then, a fan is placed on the fan bracket 904. Gas buffer pipe 906 is fixed by fastening nut 905; porous flow equalizer 907 is placed on the upper part of gas buffer pipe 906, and then solid propellant clamp 802 holding solid propellant 801 is placed at the center of porous flow equalizer 907; then the flue gas flow device base 908 is fixed with fixing pin 909 to keep flue gas flow device observation window 910 aligned with the axis of visualization window 203; annular porous filter 912 is placed on the boss 206 in visualization high-pressure combustion chamber and the boss 911 on the outside of flue gas flow device to trap Al2O3 particles in the gas; ignition wire 603 passes through the upper end of solid propellant 801 and the flue gas flow device observation windows 910 on both sides and is wound around ignition wire winding column 602.

[0063] Figure 3 This is a schematic diagram of the flue gas circulation device, including a flue gas circulation device base 908, a flue gas circulation device observation window 910, a flue gas circulation device external protrusion 911, and a flue gas duct 913.

[0064] The above is a schematic diagram of the implementation of a solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to the present invention. The following is the usage process of a solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology.

[0065] During use, follow as follows Figure 1 The diagram shows an implementation schematic of a solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology. The various devices are installed and connected; according to... Figure 2 The high-pressure combustion chamber internal structure sectional view is visualized. After installing the high-pressure resistant sapphire lens 204, the igniter terminal 601, the ignition wire winding post 602, and the four smoke purging system brackets 901 are installed on the lower end cover 205 of the combustion chamber.

[0066] Open the upper cover 202 of the combustion chamber to open the sealed, visible high-pressure combustion chamber. Install the fan bracket 904, which supports the fan motor 902 and fan blades 903, on the smoke purging system bracket 901. Then, place the gas buffer pipe 906 on the fan bracket 904 and fix it with the fastening nut 905. Place a multi-hole flow equalizer 907 above the gas buffer pipe 906 to generate a continuous and stable airflow.

[0067] Cut solid propellant 801 into blocks with a thickness of 5mm, a width of 5mm, and a length of 20mm. Pass the ignition wire 603 through the upper end of the solid propellant 801, so that the solid propellant 801 is in the middle of the propellant ignition wire 603. Clamp the lower end of the solid propellant 801 with the solid propellant clamp 802 and place it in the middle of the porous flow equalizer 907 so that the solid propellant 801 can appear in the middle of the observation field of view.

[0068] The flue gas flow device is placed above the porous flow equalizer 907, keeping the observation window 910 of the flue gas flow device aligned with the axis of the visualization window 203, and the inner boss 206 of the high-pressure combustion chamber and the outer boss 911 of the flue gas flow device at the same horizontal position. The fixing pin 909 is used to pass through the through hole in the base 908 of the flue gas flow device and fix it to the buffer pipe 906 to prevent the airflow from causing shaking.

[0069] The ignition wire 603 is passed through the observation windows 910 of the flue gas flow device on both sides and wound around the ignition wire winding post 602. The position of the ignition wire 603 is adjusted to prevent it from contacting the flue gas flow device and causing a short circuit in the ignition circuit, thus preventing ignition. The annular porous filter 912 is placed on the platform formed by the protrusion 206 in the visualization high-pressure combustion chamber and the protrusion 911 on the outside of the flue gas flow device to trap Al2O3 particles in the mixed gas flow and prevent them from affecting the observation field of view.

[0070] Adjust the camera lens 702 to enhance the light intake brightness, take a real picture of the solid propellant 801, and use the length of its upper end face as the scale length to provide a basis for subsequent calculations; install the narrowband filter 703 on the front end of the camera lens 702.

[0071] After the visualization of the internal device of the high-pressure combustion chamber is completed, the upper end cover 202 of the combustion chamber and the high-pressure combustion chamber cavity 201 are fixed with bolts to form a sealed space. During the test, the airflow generated by the smoke purging device is mixed with the airflow of the combustion products of the solid propellant (801) and then transported vertically upward through the flue gas duct (913) and then returned through the annular channel.

[0072] The exhaust solenoid valve 107 is closed and the intake solenoid valve 101 is opened using the control panel 106. The booster 103 is then started to inject nitrogen into the visible high-pressure combustion chamber. The pressure sensor 403 detects the pressure signal. When the pressure inside the visible high-pressure combustion chamber exceeds 1-1.5 MPa, the intake solenoid valve 101 is closed and the exhaust solenoid valve 107 is opened until the pressure in the visible high-pressure combustion chamber drops to atmospheric pressure. This process of charging at 1 MPa and then venting is repeated 3-5 times to completely remove the air from the visible high-pressure combustion chamber. Subsequently, the pressure in the visible high-pressure combustion chamber is increased to the required experimental pressure conditions, and the intake solenoid valve 101 is closed.

[0073] The fan electrode 902 is activated to drive the fan blades 903 to rotate, causing the airflow to circulate through the inside of the flue gas duct 913 and the annular return channel formed by the flue gas duct 913 and the high-pressure combustion chamber cavity 201 for more than 1-2 minutes, so that the gas inside the visible high-pressure combustion chamber flows stably.

[0074] First, the laser cooler 306 is opened to prevent damage to the internal precision components caused by directly opening the laser 305. The laser 305 is set to output a low-frequency light source. The grating 304 is opened to allow the light source to pass through the flexible light guide arm 303. Finally, the beam shaper 302 adjusts the angle, position, and thickness of the sheet light source 301 to produce a thin and bright high-frequency sheet light source 301.

[0075] Use the camera control software to adjust the shooting frequency of the dual-frame high-frequency shooting camera 701; set the laser 305 to output a high-frequency light source, and let the sheet light source 301 pass through the high-pressure resistant sapphire lens 204 and the observation window 910 of the flue gas circulation device to illuminate the area above the solid propellant 801; press the ignition button on the control panel 106 to ignite the solid propellant 801, and at the same time press the shooting button on the camera control software to obtain an image of the Al2O3 particles burning under high pressure in the solid propellant; stop shooting after the solid propellant 801 has finished burning, and let the smoke purging and filtration system continue to work for 1-2 minutes to completely filter the Al2O3 particles in the mixed gas.

[0076] Open the exhaust solenoid valve 107 to discharge the gas inside the visible high-pressure combustion chamber. When the pressure is consistent with the atmospheric pressure, open the upper cover 202 of the combustion chamber. Repeat the above steps to carry out multiple sample experiments.

[0077] The images of Al2O3 particles captured by the dual-frame high-frequency camera 701 were browsed and analyzed. Problematic images were excluded, and the Al2O3 particle images that needed to be processed were imported into a dedicated particle image velocimetry software. The length on the real image of the solid propellant 801 was used as a scale for analysis to obtain the flow field distribution of the solid propellant 801 during high-pressure combustion. Subsequently, the calculated flow field data was imported into dedicated plotting software such as Tecplot to draw flow field cloud maps and trace maps. The curve changes at corresponding times and positions were extracted as needed for quantitative analysis of the combustion flow field distribution.

Claims

1. A solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology, characterized in that, It includes a visualized high-pressure combustion chamber and an ignition system; the visualized high-pressure combustion chamber includes a high-pressure combustion chamber cavity (201), multiple visualized windows (203) arranged around the side of the visualized high-pressure combustion chamber, a high-pressure gas delivery pipe (102) installed at the lower part of the high-pressure combustion chamber cavity (201), an exhaust pipe (108) installed at the upper part of the high-pressure combustion chamber cavity (201), a smoke purging and filtration system and a solid propellant placement platform for placing aluminum particle solid propellant are installed inside the high-pressure combustion chamber cavity (201); it also includes a high-frequency laser system for illuminating the Al2O3 particles generated by the combustion of solid propellant (801) and a dual-frame high-frequency imaging system for photographing the Al2O3 particles generated by the combustion of the illuminated solid propellant (801); The smoke purging and filtration system includes a smoke purging device, a flue gas circulation device, and a smoke removal device. The flue gas circulation device is mounted on the smoke purging device. An annular channel is formed between the side of the smoke purging device and the side of the flue gas circulation device and the wall of the high-pressure combustion chamber (201). The smoke removal device is located at the upper part of the annular channel. The upper outlet of the flue gas circulation device is higher than the placement height of the smoke removal device. There is a gap between the top of the flue gas circulation device and the upper end of the high-pressure combustion chamber (201). The gap between the lower part of the smoke purging device and the lower end of the high-pressure combustion chamber (201) forms an airflow inlet. The lower end of the annular channel is connected to the airflow inlet. A solid propellant placement platform, located within the flue gas circulation device, is mounted on top of the smoke purging device; During the test, the airflow generated by the smoke purging device is mixed with the airflow of the combustion products of the solid propellant (801) and then transported vertically upward through the flue gas flow channel. Subsequently, it flows back from the airflow inlet at the bottom of the smoke purging device through the smoke removal device and the annular channel.

2. The solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to claim 1, characterized in that, The dual-frame high-frequency imaging system includes a dual-frame high-frequency imaging camera (701), and a narrow-band filter (703) is installed in front of the camera lens (702) in the dual-frame high-frequency imaging system; the high-frequency laser system and the dual-frame high-frequency imaging system are respectively associated with a visualization window (203); the visualization window (203) associated with the dual-frame high-frequency imaging camera (701) and the visualization window (203) associated with the high-frequency laser system are arranged at 90°; The high-frequency laser system includes a laser (305) placed above a laser cooler (306). After the laser (305) is activated to generate a light source, it passes through a grating (304), a light guide arm (303), and a beam shaper (302) in sequence to generate a sheet light source (301). The sheet light source (301) enters the visualization high-pressure combustion chamber from the side of the combustion flame. The front end of the dual-frame high-frequency imaging camera (701) is equipped with a camera lens (702) and a narrowband filter (703). The dual-frame high-frequency imaging camera (701) is arranged perpendicularly to the sheet light source (301).

3. The solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to claim 1, characterized in that, The solid propellant placement platform includes a solid propellant clamp (802) for holding the solid propellant (801); during testing, the solid propellant (801) placed on the solid propellant placement platform appears in the middle of the field of view of the visualization window (203); the installation height of the smoke removal device is not lower than the field of view of the visualization window (203); The smoke purging device includes a fan located at the bottom, a porous flow equalizer (907) located at the top, and a gas buffer pipe (906) placed between the fan and the porous flow equalizer (907). A solid propellant clamp (802) holding solid propellant (801) is placed at the center of the porous flow equalizer (907). The flue gas circulation device includes a flue gas duct (913), the side wall of the flue gas duct (913) has a flue gas circulation device observation window (910) corresponding to the visualization window (203), the lower part of the flue gas duct (913) is a flue gas circulation device base (908), and the upper outer wall of the flue gas duct (913) has a flue gas circulation device outer protrusion (911). The smoke removal device includes an annular porous filter (912), the central hole of which passes through the outside of the flue gas duct (913) and is placed on the boss (206) inside the visible high-pressure combustion chamber and the boss (911) outside the flue gas flow device. The ignition system includes an ignition wire (603), an ignition wire winding post (602) extending into the annular channel, and an igniter terminal (601) placed outside the lower end of the visible high-pressure combustion chamber; the ignition wire (603) passes through the upper end of the solid propellant (801) and the observation windows (910) of the flue gas flow device on the left and right sides and is wound around the ignition wire winding post (602).

4. The solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to claim 3, characterized in that, The fan includes a fan motor (902), fan blades (903), and a fan bracket (904). The smoke purging system bracket (901) is installed on the lower end cover (205) of the combustion chamber. The fan bracket (904) for supporting the fan motor (902) and fan blades (903) is installed on the smoke purging system bracket (901). A gas buffer pipe (906) is placed on the fan bracket (904) and fixed by a fastening nut (905). A porous flow equalizer (907) is placed on the upper part of the gas buffer pipe (906). A solid propellant clamp (802) holding solid propellant (801) is placed at the center of the porous flow equalizer (907). A fixing pin (909) fixes the flue gas circulation device base (908). The observation window (910) of the flue gas circulation device and the visualization window (203) are on the same straight line.

5. The solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to claim 1, characterized in that, The exhaust pipe (108) is installed on the upper part of the high-pressure combustion chamber cavity (201) of the smoke removal device; the high-pressure gas delivery pipe (102) is connected to the high-purity nitrogen cylinder (104) through the booster (103), the high-pressure gas delivery pipe (102) is equipped with an intake solenoid valve (101), the exhaust pipe (108) is equipped with an exhaust solenoid valve (107), the booster (103), the intake solenoid valve (101), the exhaust solenoid valve (107), and the igniter external terminal (601) are connected and remotely controlled through the control panel (106) to form an intake and exhaust control system; the high-purity nitrogen cylinder (104) is connected to the booster (103) through the low-pressure gas delivery pipe (105).

6. The solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to claim 1, characterized in that, The high-pressure combustion chamber cavity (201) forms a sealed container with the upper end cover (202) and the lower end cover (205) of the combustion chamber; the visualization window (203) is equipped with a high-pressure resistant sapphire lens (204).

7. The solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to claim 5, characterized in that, It also includes a synchronization controller (501) for synchronizing the operation of the dual-frame high-frequency camera and the high-frequency laser system, and a data acquisition and processing system; the data acquisition and processing system includes a sensor for detecting the environmental status signal inside the high-pressure combustion chamber cavity (201), a data acquisition system (402) connected to the sensor, and a data processing system (401). The sensor includes a pressure sensor (403) and a temperature sensor (404). The data processing system (401) is connected to the data acquisition system (402) and the synchronization controller (501).

8. A method for installing a solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology, characterized in that, A high-pressure resistant sapphire lens (204) is installed on the visualization window (203); the igniter external connector (601), ignition wire winding connector (602), and smoke purging system bracket (901) are installed on the lower end cover (205) of the combustion chamber; the upper end cover (202) of the combustion chamber is opened to open the sealed visualization high-pressure combustion chamber; the fan bracket (904) used to support the fan motor (902) and fan blades (903) is installed on the smoke purging system bracket (901); a gas buffer pipe (906) is placed on the fan bracket (904) and fixed by the fastening nut (905); a multi-hole flow equalizer (907) is placed above the gas buffer pipe (906) to generate a continuous and stable airflow; The ignition wire (603) passes through the upper end of the solid propellant (801), so that the solid propellant (801) is in the middle of the propellant ignition wire (603). The lower end of the solid propellant (801) is clamped by the solid propellant clamp (802) and placed in the middle of the porous flow equalizer (907), so that the solid propellant (801) can appear in the middle of the observation field. The flue gas flow device is placed above the porous flow equalizer (907), and the observation window (910) of the flue gas flow device is aligned with the axis of the visualization window (203). The inner boss (206) of the high-pressure combustion chamber and the outer boss (911) of the flue gas flow device are at the same horizontal position. The fixing pin (909) is used to pass through the through hole opened in the base (908) of the flue gas flow device and fix it on the buffer pipe (906) to prevent the airflow from causing shaking. The ignition wire (603) is passed through the observation windows (910) of the flue gas flow device on both sides and wound around the ignition wire winding post (602). The position of the ignition wire (603) is adjusted to prevent it from contacting the flue gas flow device and causing a short circuit in the ignition circuit, thus preventing ignition. The annular porous filter (912) is placed on the platform formed by the boss (206) in the visualization high-pressure combustion chamber and the boss (911) on the outside of the flue gas flow device to trap Al2O3 particles in the mixed gas flow and prevent them from affecting the observation field of view. Adjust the camera lens (702) to enhance the light intensity, take a real picture of the solid propellant (801), and use the length of its upper surface as the scale length to provide a basis for subsequent calculations; install the narrowband filter (703) on the front end of the camera lens (702); The upper end cover (202) of the combustion chamber is fixed to the high-pressure combustion chamber cavity (201) to form a sealed space.

9. The installation method of the solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology according to claim 8, characterized in that, The visualization window (203) corresponding to the dual-frame high-frequency imaging camera (701) is arranged at 90° with the visualization window (203) corresponding to the high-frequency laser system. The sheet light source (301) generated by the high-frequency laser system enters the visualization high-pressure combustion chamber from the side of the combustion flame. The front end of the dual-frame high-frequency imaging camera (701) is equipped with a camera lens (702) and a narrow-band filter (703). The dual-frame high-frequency imaging camera (701) is arranged perpendicular to the sheet light source (301). A high-purity nitrogen cylinder (104) is connected to a booster (103) via a low-pressure gas delivery pipeline (105); a high-pressure gas delivery pipeline (102) equipped with an intake solenoid valve (101) is connected at both ends to the booster (103) and the high-pressure combustion chamber (201); an exhaust solenoid valve (107) is installed in the exhaust pipeline (108) installed on the upper part of the high-pressure combustion chamber (201); the wiring of the booster (103), the intake solenoid valve (101), the exhaust solenoid valve (107), and the igniter external terminal (601) are all remotely controlled via a control panel (106).

10. A method for testing the high-pressure combustion flow field of solid propellants based on particle image velocimetry, characterized in that, The solid propellant high-pressure combustion flow field testing device based on particle image velocimetry technology as described in claim 1 includes the following steps: (1) Connect the data acquisition and processing system, the synchronization controller (501), the dual-frame high-frequency camera (701), and the high-frequency laser system control cables, and open the corresponding dual-frame high-frequency camera and high-frequency laser system control software on the data processing system (401). (2) Cut the solid propellant block and pass the ignition wire through the upper surface of the solid propellant block from the side. Clamp the solid propellant block on the solid propellant placement platform and place the solid propellant placement platform in the middle position of the porous flow equalizer in the smoke purge device. (3) Place the flue gas flow device on the porous flow equalizer of the smoke purging device, rotate the flue gas flow device so that the four vertically distributed flue gas flow device observation windows correspond to the visual window axis of the visual high-pressure combustion chamber respectively, and fix them with fixing pins; (4) Pass the excess ignition wire through the observation window in the middle of the flue gas flow device and wrap it around the ignition wire winding column of the ignition system. Adjust the position of the ignition wire to prevent it from contacting the flue gas flow device. (5) Place the annular porous filter in the smoke removal device on the outer protrusion of the flue gas flow device and the protrusion in the visible high-pressure combustion chamber so that the Al2O3 particles in the circulating return gas are intercepted. (6) Adjust the aperture of the dual-frame high-frequency camera, take real pictures of the solid propellant, and use the length of its upper end face as the scale length to provide a basis for subsequent flow field calculations; (7) Sealed, visualized high-pressure combustion chamber; (8) Close the exhaust solenoid valve, open the intake solenoid valve, open the high-purity nitrogen cylinder, start the booster, and repeatedly fill the interior of the visible high-pressure combustion chamber with high-purity nitrogen to 1-1.5MPa, then open the exhaust solenoid valve to exhaust 3-5 times to make the visible high-pressure combustion chamber completely filled with high-purity nitrogen atmosphere. (9) Close the exhaust solenoid valve, open the intake solenoid valve to charge the air so that the pressure inside the visible high-pressure combustion chamber is increased to the set value, and then close the intake solenoid valve. (10) Start the smoke purging device and continue for 1-2 minutes to stabilize the gas flow inside the visible high-pressure combustion chamber; (11) Turn on the high-frequency laser system to generate a high-frequency pulse plate light source, and adjust the angle, position and thickness of the plate light source so that the thin and bright plate light source can completely illuminate the area to be observed; (12) Install the narrowband filter on the front of the lens of the dual-frame high-frequency camera; (13) Set the output frequency of the high-frequency laser system and the shooting frequency parameters of the dual-frame high-frequency camera; (14) Turn on the high-frequency laser system, ignite the solid propellant and press the dual-frame high-frequency camera shooting button at the same time to obtain the high-pressure combustion flow field image of the solid propellant. (15) Open the exhaust solenoid valve to release the gas inside the visible high-pressure combustion chamber; (16) To conduct experiments on multiple samples, steps (2)-(15) need to be repeated; (17) Browse, analyze and eliminate problematic images, select the solid propellant high-pressure combustion flow field image to be processed, and input it into the dedicated software for particle image velocity measurement to obtain data information; (18) Import the combustion flow data information obtained from the image into the Tecplot plotting software to draw the flow field cloud map and trace map, and extract the curve changes at the corresponding time and position as needed for quantitative analysis of the combustion flow field distribution.

Images