Experimental system for investigating the microburst vaporization and combustion of droplet groups at high temperature and high pressure

Abstract

Test system for investigating the microburst vaporization and combustion of droplet groups at high temperature and high pressure, comprising a high-pressure fixed-volume bomb, a heating furnace (3), a test and image acquisition device, and a pressurization device, wherein the high-pressure fixed-volume bomb comprises a high-temperature high-pressure fixed-volume bomb (12) and a low-temperature high-pressure fixed-volume bomb (17) connected to each other by a high-pressure ball valve (15), and wherein the heating furnace (3) is arranged in the high-temperature high-pressure fixed-volume bomb (12), and wherein the test and image acquisition device is arranged outside the high-temperature high-pressure fixed-volume bomb (12).to capture images of droplet groups in the high-temperature, high-pressure, fixed-volume bomb (12); and wherein the pressurization device is connected to the high-temperature, high-pressure, fixed-volume bomb (12) and low-temperature, high-pressure, fixed-volume bomb (17) respectively to provide a working pressure for these, characterized in that the experimental system further comprises a device for generating and suspending droplet groups and a device for conveying droplet groups arranged in the low-temperature, high-pressure, fixed-volume bomb (17), wherein the device for generating and suspending droplet groups comprises a droplet generator (25) and a droplet group suspension frame (16), and wherein the droplet group suspension frame (16) is arranged on the device for conveying droplet groups and is located below the droplet generator (25), and wherein,when the high-pressure ball valve (15) is closed, the droplet generator (25) generates the droplets and the droplets are suspended on the droplet group suspension frame (16), and wherein, when the high-pressure ball valve (15) is open, the device for conveying droplet groups moves the droplet group suspension frame (16) with the suspended droplets into the heating oven (3).

Description

TECHNICAL FIELD

[0001] The present utility model relates to the technical field of test equipment for engine combustion and, in particular, to a test system for investigating microburst evaporation and combustion of groups of droplets at high temperature and high pressure. STATE OF THE ART

[0002] Advanced engine technology is the core technology of space exploration, aerospace, ocean exploration, and other fields. International engine research is moving toward ultra-high efficiency and near-zero emissions. China's engine research started late, the foundation is weak, and advanced engine technology is subject to constraints. For example, China's third-generation aircraft engines have long relied on Russian imports of the AL-31F turbofan engine. The theoretical and technological support for controlled combustion technology in advanced engines is lacking. This represents a major gap with the international advanced level and has become a technical bottleneck for national defense, science and technology, and economic construction.In the new period, China's aerospace and maritime industries will be further developed, and the research and development requirements of the long-term development of high-performance aircraft engines, ramjet engines, rocket engines, marine engines and other key projects on the controlled combustion technology of the engine will become more and more urgent.

[0003] Spray combustion is the key to research into controlled engine combustion. The spray combustion process, the atomization, vaporization, and combustion of liquid fuel, is an important part of the engine's ability to achieve ultra-high efficiency and near-zero emissions. It directly affects the formation of combustible mixtures, the distribution of fuel vapor concentration, and the energy conversion rate. Among the many programs to improve spray combustion efficiency, microburst vaporization and combustion are relatively mature at this stage and have potential for application.The microburst of droplets ejects small droplets and vapor. Steam injection accelerates flame propagation between the droplets. The microburst can quickly break the droplets into smaller droplets, achieving secondary atomization and accelerating fuel vaporization, oil and gas mixing, and combustion, while simultaneously reducing emissions. The droplets in the spray flow field are not sparsely distributed and maintain the clustered shape of ignition and combustion. The vaporization and combustion of droplet groups have many similarities with spray combustion, and both are involved in the motion boundary effect, unsteady heat conduction, mass diffusion, interfacial phase equilibrium, radiation dynamics, and the kinetics of combustion chemical reactions.Therefore, microburst evaporation and combustion of droplet groups is crucial for the investigation of ultra-high efficiency, near-zero emission engines.

[0004] Most traditional droplet evaporation and combustion experimental devices can only study the evaporation and combustion of a single droplet. High-pressure experimental devices require the simultaneous existence of two fixed-volume bombs at two temperatures. That is, in the low-temperature high-pressure fixed-volume bomb, droplets are generated and suspended, while in the high-temperature high-pressure fixed-volume bomb, droplet evaporation and combustion are realized. However, the high-temperature and low-temperature high-pressure fixed-volume bombs are connected to each other, and the temperature difference is very large, resulting in strong convection. The low-temperature high-pressure fixed-volume bomb has a relatively high temperature, and the droplets are evaporated first (evaporation begins even before the experiment begins, which affects the accuracy of the experiment).For fuel droplets with microburst characteristics, the low-boiling point components are already completely vaporized before the droplets enter the high-temperature environment, so their vaporization and combustion cannot be studied. On the other hand, the high-temperature, high-pressure, fixed-volume bomb has large temperature fluctuations, making it difficult to ensure temperature uniformity and simultaneously achieve ultra-high-temperature and ultra-high-pressure environments. Furthermore, the vaporization and combustion of the droplets in the supercritical environment cannot be studied. Furthermore, due to the small diameter of the droplets (about 1 / 3 of an inch), the vaporization and combustion of the droplets in the supercritical environment cannot be studied.1mm) requires more time to generate the droplet groups, but the traditional experimental equipment for droplet evaporation and combustion cannot achieve the isolation environments of low and high temperatures simultaneously for a long period of time, so it is not possible to study the evaporation and combustion of droplet groups. CONTENT OF THE PRESENT UTILITY MODEL

[0005] In order to solve the above-mentioned technical problems, a purpose of the present utility model is to provide an experimental system for studying the microburst evaporation and combustion of droplet groups at high temperature and high pressure, wherein two fixed-volume bombs of the system are isolated from each other and the high-temperature and low-temperature isolation environments can be maintained for a long period of time, whereby, under the premise of not being affected by the high-temperature, high-pressure, fixed-volume bomb, the droplets can be suspended for a long period of time to study the microburst, evaporation and combustion of the individual droplets and the droplet groups, and the flame propagation between the droplets.

[0006] In order to achieve the above purpose of the present utility model, the present utility model uses the following technical solution: An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure, comprising a high-pressure, fixed-volume bomb, a heating furnace, a test and image acquisition device, and a pressurization device, wherein the high-pressure, fixed-volume bomb comprises a high-temperature, fixed-volume high-pressure bomb and a low-temperature, fixed-volume high-pressure bomb connected to each other by a high-pressure ball valve, and wherein the heating furnace is arranged in the high-temperature, fixed-volume high-pressure bomb, and wherein the test and image acquisition device is arranged outside the high-temperature, fixed-volume high-pressure bomb,to capture the images of the droplet groups in the high-temperature, high-pressure, fixed-volume bomb; and wherein the pressurization device is connected to each of the high-temperature, high-pressure, fixed-volume bomb and the low-temperature, high-pressure, fixed-volume bomb to provide a working pressure therefor, and wherein the experimental system further comprises a droplet group generating and suspending device and a droplet group conveying device arranged in the low-temperature, high-pressure, fixed-volume bomb, and wherein the droplet group generating and suspending device comprises a droplet generator and a droplet group suspending frame, and wherein the droplet group suspending frame is arranged on the droplet group conveying device and is located below the droplet generator, and wherein, when the high-pressure ball valve is closed,the droplet generator generates the droplets and the droplets are suspended from the droplet group suspension frame, and wherein, when the high-pressure ball valve is opened, the droplet group conveying device moves the droplet group suspension frame with the suspended droplets into the heating furnace.

[0007] In a preferred solution, a cooling water circulation device is further connected between the high-temperature high-pressure bomb with a fixed volume and the high-pressure ball valve, which is connected to a cooling water bottle via a micro water pump.

[0008] In a preferred solution, the device for generating and suspending droplet groups further comprises a micro-syringe pump, a fuel bottle and a holder for the droplet generator, wherein the droplet generator is arranged on the upper part of the low-temperature high-pressure bomb with a fixed volume via the holder for the droplet generator, and wherein the fuel bottle is connected to the droplet generator via the micro-syringe pump.

[0009] In a preferred solution, an ultrafine glass tube for generating droplets is installed at the head of the droplet generator, wherein the openings at two ends of the ultrafine glass tube have different diameters, and wherein one end of the ultrafine glass tube with a thicker opening is connected to the head of the droplet generator, and wherein the diameter of the other end is less than or equal to the diameter of the thin part of 1 µm.

[0010] In a preferred solution, the droplet group suspension frame comprises a peripheral frame and inner suspension wires, wherein the plurality of suspension wires are evenly distributed and crisscrossed to form intersection points for suspending droplets, and wherein the diameter of the suspension wire is less than or equal to 0.1 mm.

[0011] In a preferred solution, the droplet group conveying device comprises a servomotor synchronous belt moving mechanism and a support rod, wherein one end of the support rod is fixed to the servomotor synchronous belt moving mechanism and the other end of the support rod is fixed to the droplet group hanging frame, and wherein the servomotor synchronous belt moving mechanism drives the support rod to move between the heating furnace and the droplet generator, and wherein the servomotor synchronous belt moving mechanism is further connected to a servomotor controller arranged outside the low-temperature high-pressure fixed-volume bomb.

[0012] In a preferred solution, a first viewing window A and a first viewing window B are arranged on the left and right sides of the high-temperature, high-pressure, fixed-volume bomb, respectively, and a second viewing window A and a second viewing window B are arranged on the left and right sides of the heating furnace, respectively, and the first viewing window A, the first viewing window B, the second viewing window A and the second viewing window B are located on the same straight line.

[0013] In a preferred solution, the testing and image acquisition device comprises a high-speed camera and a backlight, wherein the high-speed camera and the backlight face the first viewing window A and the first viewing window B, respectively, and are located on the same straight line with the first viewing window A and the first viewing window B.

[0014] In a preferred solution, a heating wire is arranged in the side wall of the heating furnace, wherein an upper thermocouple and a lower thermocouple are arranged in the heating furnace for measuring the temperatures at the top and bottom of the heating furnace, respectively, and wherein the bottom of the heating furnace is further provided with a droplet inlet, and wherein a thermal insulation layer is further arranged on the outside of the heating furnace, and wherein the heating furnace is further connected to a temperature controller arranged outside the high-temperature, high-pressure bomb with a fixed volume.

[0015] In a preferred solution, two sets of pressurization devices are provided, which are independently connected to the high-temperature, high-pressure, fixed-volume bomb and the low-temperature, high-pressure, fixed-volume bomb for pressurization.

[0016] Compared to the prior art, the present utility model has the following advantages: 1. This utility model uses two fixed-volume high-pressure bombs to respectively achieve a high-temperature and high-pressure environment and a low-temperature and high-pressure environment to simultaneously achieve a low-temperature and high-temperature insulating environment, thereby avoiding the influence of high temperature on droplet evaporation and combustion during droplet generation and suspension, and easily completing droplet generation and suspension in a high-pressure environment, so as to realize the study of droplet group evaporation and combustion, and solve the problem that the existing experimental equipment is unable to study the microburst evaporation and combustion of droplet groups; 2. In the present utility model, the low-temperature high-pressure fixed-volume bomb is located at the bottom of the high-temperature high-pressure fixed-volume bomb to avoid the influence of convection on the droplets when they enter the high-temperature environment. Furthermore, the present utility model uses a heating furnace built into the fixed-volume bomb, and the temperature in the heating furnace is not affected by the environment and is more uniform and stable. SHORT DESCRIPTION OF THE DRAWING

[0017] The accompanying drawings, which form a part of the present application, provide a further understanding of the present application. The exemplary embodiments of the present application and their discussion are intended to explain the present application and do not constitute a limitation on the present application. Fig. Figure 1 shows a schematic diagram of the overall structure of the present utility model. Fig. 2 shows a schematic diagram of the sectional structure of a heating furnace according to the present utility model. Fig. 3 shows a schematic diagram of the structure of a droplet group suspension frame (in a suspension state of the droplet groups) according to the present utility model. List of reference symbols 1-1 Access valve A 1-2 Access valve B 2-1 Safety valve A 2-2 Safety valve B 3 heaters 4 Thermal insulation layer 5-1 Nitrogen cylinder A 5-2 Nitrogen cylinder B 6-1 Air bottle A 6-2 Air bottle B 7-1 First viewing window A 7-2 First viewing window B 8-1 Small sapphire crystal A 8-2 Small sapphire crystal B 9 High-speed camera 10-1 Second viewing window A 10-2 Second viewing window B 11-1 Quartz glass A 11-2 Quartz glass B 12 high-temperature high-pressure bomb with fixed volume 13-1 Computer A 13-2 Computer B 14 Cooling water circulation device 15 High pressure ball valve 16 droplet group hanging frames 17 Low-temperature high-pressure bomb with fixed volume 18 Servo motor synchronous belt movement device 19 Support rod 20-1 Booster pump B 20-2 Booster pump A 21 Micro syringe pump 22 fuel bottle 23 servo motor controllers 24 Holder for the droplet generator 25 droplet generator 26 Large sapphire crystal 27 Third viewing window 28 Cooling water bottle 29 Micro water pump 30 backlight 31 temperature controllers 32 Upper thermocouple 33 heating wire 34 Lower thermocouple 35 Droplet inlet 36 droplets 37 Suspension wire DETAILED DESCRIPTION

[0018] The present utility model is explained in more detail below in conjunction with the attached drawings and exemplary embodiments.

[0019] As in Fig. 1 shows an experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure, comprising a high-pressure, fixed-volume bomb, a heating furnace 3, a testing and image acquisition device, and a pressurization device. The high-pressure, fixed-volume bomb comprises a high-temperature, fixed-volume high-pressure bomb 12, a high-pressure ball valve 15, and a low-temperature, fixed-volume high-pressure bomb 17. The high-temperature, fixed-volume high-pressure bomb 12 is made of stainless steel 304 and is provided with an access valve A1-1, a safety valve A2-1, and a high-flow inlet A at the top. The high-temperature, fixed-volume high-pressure bomb 12 is provided on the left and right sides with a first viewing window A7-1 and a first viewing window B7-2 facing each other.and wherein the high-temperature, high-pressure, fixed-volume bomb 12 is provided with a through-hole at the bottom for the entry of droplets. Since the fixed-volume bomb must withstand high pressure, a small sapphire crystal A8-1 and a small sapphire crystal B8-2 are arranged in a cylindrical shape in the first viewing window A7-1 and the first viewing window B7-2, respectively.

[0020] The low-temperature high-pressure fixed-volume bomb 17 is located directly below the high-temperature high-pressure fixed-volume bomb 12 and is connected to the high-temperature high-pressure fixed-volume bomb 12 through the high-pressure ball valve 15. A third viewing window 27 is arranged on the right side of the low-temperature high-pressure fixed-volume bomb 17 for observing the droplet suspension situation. The low-temperature high-pressure fixed-volume bomb 17 is equipped with an access valve B1-2, a safety valve B2-2, and a high-flow inlet B at the bottom and a through hole at the top. The third viewing window 27 is removable and has a large cylindrical sapphire crystal 26 inside.

[0021] Between the high-temperature, fixed-volume, high-pressure bomb 12 and the high-pressure ball valve 15, a cooling water circulation device 14 is further connected. The cooling water circulation device 14 is annular and connected to a cooling water bottle 28 via a micro water pump 29. The micro water pump 29 continuously supplies cooling water into the cooling water circulation device to reduce the heat transfer of the high temperature of the top surface to the high-pressure ball valve 15. The cooling water circulation device 14 can reduce the influence of the high temperature on the low-temperature, fixed-volume, high-pressure bomb, and the high-pressure ball valve 15 can be freely opened or closed. In one embodiment, the ball valve 15 is closed at the beginning of the experiment and opened after the droplets are suspended, and the droplets enter the high-temperature, high-pressure bomb body 12.

[0022] The heating furnace 3 is arranged in the high-temperature high-pressure bomb with fixed volume 12, the specific structure of the heating furnace is as shown in Fig. 2, wherein a second viewing window A10-1 and a second viewing window B10-2 are arranged on the left and right sides of the heating furnace 3, respectively, and wherein the first viewing window A7-1, the first viewing window B7-2, the second viewing window A10-1, and the second viewing window B10-2 are located on the same straight line. A round quartz glass A11-1 and a cylindrical quartz glass B11-2 are arranged in the second viewing window A10-1 and the second viewing window B10-2, respectively.

[0023] The heating furnace 3 is cylindrical and made of 304 stainless steel, which is wound with heating wires 33 inside. The heating wires 33 are evenly wound around the heating furnace while bypassing the second viewing window A 10-1 and the second viewing window B 10-2. The heating furnace 3 is further provided with a droplet inlet 35 at the bottom, which faces the through hole at the bottom of the high-temperature, high-pressure, fixed-volume bomb 12. For thermal insulation, a layer of high-temperature-resistant thermal insulation material is wrapped around the outside of the heating furnace 3 to form a thermal insulation layer 4.

[0024] An upper thermocouple 32 and a lower thermocouple 34 are arranged in the heating furnace 3 for measuring the temperatures at the top and bottom of the heating furnace 3, respectively. The heating furnace 3 is further connected to a temperature controller 31 arranged outside the high-temperature, high-pressure, fixed-volume bomb 12. The temperature controller 31 is connected to the heating furnace 3 through the high-flow inlet A at the top of the high-temperature, high-pressure, fixed-volume bomb 12 to control the temperature of the heating furnace 3. In the experiment, when the temperatures of the upper thermocouple 32 and the lower thermocouple 34 are the same, it is assumed that the temperature inside the heating furnace 3 is uniform and the test conditions are met.

[0025] In the low-temperature high-pressure bomb with a fixed volume 17, a device for generating and suspending droplet groups and a device for conveying droplet groups are further arranged, wherein the device for generating and suspending droplet groups comprises a droplet generator 25 and a droplet group suspension frame 16, and wherein the droplet group suspension frame 16 is arranged on the device for conveying droplet groups and is located below the droplet generator 25, and wherein, when the high-pressure ball valve 15 is closed, the droplet generator 25 generates the droplets and the droplets are suspended on the droplet group suspension frame 16, and wherein, when the high-pressure ball valve 15 is opened, the device for conveying droplet groups moves the droplet group suspension frame 16 with the suspended droplets into the heating furnace 3.

[0026] The device for generating and suspending droplet groups further comprises a micro-syringe pump 21, a fuel bottle 22 and a holder for the droplet generator 24, wherein the droplet generator 25 is arranged on the top of the low-temperature high-pressure fixed-volume bomb 17 via the holder for the droplet generator 24, and wherein the micro-syringe pump 21 can precisely control the volume of the generated droplets and is connected to the 25 and the fuel bottle 22 to generate the droplets at the tip portion of the droplet generator 25.

[0027] In one of the technical solutions of the utility model, the fuel in the fuel cylinder 22 comprises a mixture of low-boiling point fuel and high-boiling point fuel, wherein the low-boiling point fuel comprises methanol, ethanol, propanol, butanol, pentanol, 2-dimethylfuran, 2,5-dimethylfuran and gasoline, and the high-boiling point fuel comprises diesel oil, biodiesel, pyrolyzed bio-oil, pure vegetable oil, n-heptane, n-decane, n-hexadecane, petroleum and hard coal oil.

[0028] The droplet generator 25 is provided with an ultrafine glass tube for generating droplets at its head. The ultrafine glass tube is manufactured by drawing a glass capillary tube using a drawing device and has a thick end and a thin end. The thick end is connected to the head of the droplet generator 25, and the thin end generates droplets. The diameter of the thin end does not exceed 1 µm.

[0029] The droplet group suspension frame 16 is square, and the specific structure is as shown in Fig. 3, comprising a peripheral frame and internal suspension wires 37, wherein the plurality of suspension wires are evenly distributed and crisscrossed to form intersection points for suspending droplets 36. After the droplet generator 25 generates the droplets 36, it is moved to the intersection point of the suspension wires 37 in the droplet suspension frame, and suspension is achieved by utilizing surface tension. To avoid the influence of the suspension wires 37 on the evaporation and combustion of the droplets, the diameter of the suspension wires must not exceed 0.1 mm, and the material is quartz, silicon carbide, or ceramic fiber.

[0030] The droplet suspension frame of the present utility model can be used to suspend a plurality of droplets or droplet groups through a layer of droplet suspension frames to study the vaporization and combustion of a two-dimensional droplet group, which is conducive to studying the interactions between droplets; also, multiple droplet suspension frames can be used to suspend a large number of droplet groups to study the vaporization and combustion of a three-dimensional droplet group, which is conducive to studying the vaporization and combustion characteristics of actual three-dimensional droplet groups.

[0031] The droplet group conveying device comprises a servomotor synchronous belt moving mechanism 18, a support rod 19, and a servomotor controller 23. One end of the support rod 19 is fixed to the servomotor synchronous belt moving mechanism 18 and faces the through hole on the top of the low-temperature high-pressure fixed-volume bomb, and the other end of the support rod 19 is fixed to the droplet group hanging frame 16;and wherein the servomotor-synchronous belt moving device 18 is connected to the servomotor controller 23 through the high-flow inlet B at the bottom of the low-temperature, high-pressure, fixed-volume bomb 17 and is capable of driving the support rod 19 to move vertically quickly and accurately between the heating furnace 3 and the droplet generator 25. After a program is input to the servomotor controller 23, the servomotor-synchronous belt moving device 18 can move quickly to the specified position with a very short response time, which reduces the effect of heat on the droplets during the process of the droplet groups entering the high-temperature environment.

[0032] The servo motor controller 23 and the temperature controller 31 in the heating furnace are further connected to a computer B 13-2, by which the above-described mechanisms are jointly controlled.

[0033] The testing and image acquisition device is arranged outside the high-temperature, high-pressure, fixed-volume bomb 12 to acquire images of the droplet groups in the high-temperature, high-pressure, fixed-volume bomb 12; the testing and image acquisition device includes a high-speed camera 9, a computer A 13-1, and a backlight 30, wherein the high-speed camera 9 and the backlight 30 face the first viewing window A 7-1 and the first viewing window B 7-2, respectively, and are located on the same straight line with the first viewing window A 7-1 and the first viewing window B 7-2.

[0034] Due to the high speed of the microburst, the high-speed camera 9 must have high resolution and a high frame rate, and the backlight is a xenon or LED lamp. The backlight 30 serves as the light source, and the high-speed camera 9 captures images of droplets and flames. Then, through image processing, the computer A 13-1 obtains the experimental data of droplet evaporation and combustion. Computer A 13-1 and computer B 13-2 can be the same computer.

[0035] The entire experimental system is provided with two sets of independent pressurization devices, one set is used to pressurize the high-temperature high-pressure fixed-volume bomb 12 and another set is used to pressurize the low-temperature high-pressure fixed-volume bomb, and the two sets of systems are completely independent of each other and do not affect each other.

[0036] Each set of pressurizing devices comprises a booster pump, a nitrogen cylinder, and an air cylinder, wherein the outlet of the booster pump A 20-2 in each set of pressurizing devices is connected to the access valve A 1-1 on the high-temperature, high-pressure, fixed-volume bomb 12, and wherein the inlet of the booster pump A 20-2 is connected to the nitrogen cylinder A 5-1 and the air cylinder A 6-1; and wherein the outlet of the booster pump B 20-1 in another set of pressurizing devices is connected to the access valve B 1-2 on the low-temperature, high-pressure, fixed-volume bomb 17, and wherein the inlet of the booster pump B 20-1 is connected to the nitrogen cylinder B 5-2 and the air cylinder B 6-2.

[0037] Pressurization in the fixed-volume high-temperature high-pressure bomb and the fixed-volume low-temperature high-pressure bomb with nitrogen prevents self-ignition of the droplets and enables the study of microburst evaporation on the droplets; pressurization in the fixed-volume high-temperature high-pressure bomb and the fixed-volume low-temperature high-pressure bomb with air enables the study of microburst combustion on the droplets.

[0038] In the device according to the present utility model, the pressure of the high-temperature high-pressure bomb with a fixed volume can exceed the critical pressure of the fuel, the temperature of the heating furnace can also exceed the critical temperature of the fuel, in order to facilitate the personnel of investigating the evaporation and combustion properties of the droplets under supercritical conditions.

[0039] The experimental system of the present utility model has a workflow that includes the following steps: (1) Open the high-pressure ball valve 15, start the servo motor synchronous belt moving device 18, move the droplet group hanging frame 16 to the center position of the viewing window of the heating furnace, and simultaneously start the backlight 30 and the high-speed camera 9. Adjust the position of the droplet group hanging frame so that the droplet group hanging frame is exactly at the center position of the high-speed camera's viewpoint, and record the moving distance and speed of the servo motor synchronous belt moving device 18 started at this time, as well as the resolution of the high-speed camera 9, the brightness of the backlight 30, and other parameters. (2) Close the high-pressure ball valve 15 and start the micro-water pump 29, so that the cooling water circulation system begins to work. Set the target pressure of the safety valve B 2-1. Use the booster pump A 20-2 to inject high-pressure nitrogen (or air) into the high-temperature, fixed-volume high-pressure bomb 12. Stop the inflation after reaching the target pressure. Turn on the temperature controller 31 and set the target temperature, so that the heating furnace 3 begins to work. Observe the readings of the upper thermocouple 32 and the lower thermocouple 34 inside the heating furnace. When the readings of the upper and lower thermocouples are identical to each other and equal to the target pressure, further temperature increase is stopped. (3) Adjust the target pressure of the safety valve B 2-2, use the booster pump A 20-1 to inject nitrogen (or air) into the low-temperature high-pressure fixed-volume bomb 17, stop inflating when the pressure is equal to the pressure of the high-temperature high-pressure fixed-volume bomb 12. (4) Start the micro-syringe pump 21, use the droplet generator 25 to generate droplets of the same diameter. The droplet generator suspends the droplets one by one at the intersections of every two suspension wires 37, and uses the viewing window on the side surface of the fixed-volume low-temperature high-pressure bomb to observe whether the suspension position is correct. If the suspension position is inappropriate or an error occurs, the droplets are resuspended. (5) After the droplet groups are suspended, the high-pressure ball valve 15 is opened, the servo motor synchronous belt moving device 18 is started, the servo motor controller 23 is used to adjust the target distance (the data recorded in step (1)) and the moving speed, and the droplet group hanging frame is moved to the position calibrated in step (1). (6) Turn on the high-speed camera 9 and the backlight 30, use the high-speed camera 9 to photograph and record changes in the diameter of the droplets when conducting the droplet evaporation test; and use the high-speed camera to photograph and record changes in the diameter of the droplets and the flames when conducting the droplet combustion test. (7) At the end of the experiment, the droplet group suspension frame 16 is moved back into the low-temperature high-pressure fixed-volume bomb 17, the high-pressure ball valve 15 is closed, and the gas in the high-temperature high-pressure fixed-volume bomb 15 is first vented, and then the gas in the low-temperature high-pressure fixed-volume bomb 17 is vented.

[0040] In summary, the device of the present utility model uses two fixed-volume bombs (high-temperature and low-temperature high-pressure fixed-volume bombs) designed and separated independently, pressurized independently, and non-interfering with each other. The device can maintain high-temperature and low-temperature isolation environments for a long period of time. This device, provided it is not affected by the high-temperature high-pressure fixed-volume bomb, can suspend droplets for a long period of time to study the microburst, vaporization, and combustion of individual droplets and droplet groups, as well as flame propagation between droplets.Furthermore, the high-temperature high-pressure bomb body uses a built-in heating furnace and is not disturbed by the external environment to realize a stable high-temperature and high-pressure environment.

[0041] In this description, the explanation in connection with the technical terms "an embodiment," "some embodiments," "an example," "a specific example," or "some examples" refers to the fact that the specific features, structures, materials, or features explained in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this description, the schematic representations of the above technical terms do not necessarily refer to the same embodiment or example. Furthermore, the explained specific features, structures, materials, or features can be combined in one or more embodiments or examples as appropriate.

[0042] Although the embodiments of the present utility model are illustrated and explained above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present utility model. Those skilled in the art can make changes, modifications, substitutions, and variations to the embodiments within the scope of the present utility model without departing from the principle and spirit of the present utility model. All simple variations and equivalent changes and modifications to the above embodiments based on the technical essence of the present utility model should be considered to be within the scope of the technical solutions of the present utility model.

Claims

[1] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure, comprising a high-pressure, fixed-volume bomb, a heating furnace (3), a testing and image acquisition device, and a pressurizing device, wherein the high-pressure, fixed-volume bomb comprises a high-temperature, fixed-volume, high-pressure bomb (12) and a low-temperature, fixed-volume, high-pressure bomb (17) connected to each other by a high-pressure ball valve (15), and wherein the heating furnace (3) is arranged inside the high-temperature, fixed-volume, high-pressure bomb (12), and wherein the testing and image acquisition device is arranged outside the high-temperature, fixed-volume, high-pressure bomb (12) to acquire the images of the droplet groups in the high-temperature, fixed-volume, high-pressure bomb (12);and wherein the pressurizing device is connected to each of the high-temperature, high-pressure, fixed-volume bomb (12) and the low-temperature, high-pressure, fixed-volume bomb (17) to provide a working pressure therefor; characterized bythat the experimental system further comprises a device for generating and suspending droplet groups and a device for conveying droplet groups, which are arranged in the low-temperature high-pressure bomb with a fixed volume (17), wherein the device for generating and suspending droplet groups comprises a droplet generator (25) and a droplet group suspension frame (16), and wherein the droplet group suspension frame (16) is arranged on the device for conveying droplet groups and is located below the droplet generator (25), and wherein, when the high-pressure ball valve (15) is closed, the droplet generator (25) generates the droplets and the droplets are suspended on the droplet group suspension frame (16), and wherein, when the high-pressure ball valve (15) is opened, the device for conveying droplet groups conveys the droplet group suspension frame (16) with the suspended droplets into the heating furnace (3) moved. [2] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 1, characterized by that between the high-temperature high-pressure bomb with a fixed volume (12) and the high-pressure ball valve (15) there is also connected a cooling water circulation device (14) which is connected to a cooling water bottle (28) via a micro water pump (29). [3] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 1, characterized byin that the device for generating and suspending groups of droplets further comprises a micro-syringe pump (21), a fuel bottle (22) and a holder for the droplet generator (24), wherein the droplet generator (25) is arranged on the upper part of the low-temperature high-pressure bomb with a fixed volume (17) via the holder for the droplet generator (24), and wherein the fuel bottle (22) is connected to the droplet generator (25) via the micro-syringe pump (21). [4] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 3, characterized bythat an ultrafine glass tube for generating droplets is installed on the head of the droplet generator (25), wherein the openings at two ends of the ultrafine glass tube have different diameters, and wherein one end of the ultrafine glass tube with a thicker opening is connected to the head of the droplet generator (25), and wherein the diameter of the other end is less than or equal to the diameter of the thin part of 1 µm. [5] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 1, characterized by in that the droplet group suspension frame (16) comprises a peripheral frame and inner suspension wires (37), wherein the plurality of suspension wires are evenly distributed and crisscrossed to form intersection points for suspending droplets, and wherein the diameter of the suspension wire is less than or equal to 0.1 mm. [6] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 1, characterized by in that the device for conveying droplet groups comprises a servomotor-synchronous belt moving mechanism (18) and a support rod (19), wherein one end of the support rod (19) is fixed to the servomotor-synchronous belt moving mechanism (18) and the other end of the support rod (19) is fixed to the droplet group hanging frame (16), and wherein the servomotor-synchronous belt moving mechanism (18) drives the support rod (19) to move between the heating furnace (3) and the droplet generator (25), and wherein the servomotor-synchronous belt moving mechanism (18) is further connected to a servomotor controller (23) arranged outside the low-temperature high-pressure fixed-volume bomb (17). [7] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 1, characterized by that on the left and right sides of the high-temperature, high-pressure bomb with a fixed volume (12) a first viewing window A (7-1) and a first viewing window B (7-2) are arranged, respectively, wherein on the left and right sides of the heating furnace (3) a second viewing window A (10-1) and a second viewing window B (10-2) are arranged, respectively, and wherein the first viewing window A (7-1), the first viewing window B (7-2), the second viewing window A (10-1) and the second viewing window B (10-2) are located on the same straight line. [8] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 7, characterized byin that the testing and image capturing device comprises a high-speed camera (9) and a backlight (30), wherein the high-speed camera (9) and the backlight (30) face the first viewing window A (7-1) and the first viewing window B (7-2) respectively and are located on the same straight line with the first viewing window A (7-1) and the first viewing window B (7-2). [9] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 1, characterized bythat a heating wire (33) is arranged in the side wall of the heating furnace (3), wherein an upper thermocouple (32) and a lower thermocouple (34) for measuring the temperatures at the top and bottom of the heating furnace (3) are arranged in the heating furnace (3), respectively, and wherein the bottom of the heating furnace (3) is further provided with a droplet inlet (35), and wherein a thermal insulation layer (4) is further arranged on the outside of the heating furnace (3), and wherein the heating furnace (3) is further connected to a temperature controller (31) which is arranged outside the high-temperature, high-pressure bomb with a fixed volume (12). [10] An experimental system for investigating microburst evaporation and combustion of droplet groups at high temperature and high pressure according to claim 1, characterized bythat two sets of pressurizing devices are provided which are independently connected to the high-temperature, high-pressure, fixed-volume bomb (12) and the low-temperature, high-pressure, fixed-volume bomb (17) for pressurization.

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