Spliced temperature-controllable rectangular spray pipe observation system with nested liquid path temperature regulation function

Abstract

The invention discloses a spliced temperature-controllable rectangular spray pipe observation system with nested liquid path temperature regulation, which relates to the technical field of liquid engine plume pollution research and comprises a temperature control spray pipe, a nested temperature control liquid pipeline, an electromagnetic valve and a central computer. The temperature control spray pipe comprises a spray pipe assembly flange, a spray pipe metal side wall surface, a spray pipe thermal insulation layer and a spray pipe acrylic front plate; the spray pipe metal side wall surface is spliced and connected with the spray pipe acrylic front plate through the spray pipe thermal insulation layer; according to the invention, through the design of a nested liquid path and a spliced spray pipe, independent temperature control of three areas of the spray pipe and accurate adjustment of the temperature of an experimental medium are realized, and a temperature variable is decoupled; the splicing process solves the problem of micro-channel processing, and is matched with a heat insulation-acrylic structure to eliminate optical distortion and provide a clear observation visual angle; the integrated design of the system improves stability and applicability, and provides an efficient experimental platform for plume pollution mechanism research.

Description

Technical Field

[0001] The invention relates to the technical field of liquid engine plume pollution research, in particular to a spliced temperature-controllable rectangular nozzle observation system with nested liquid path temperature regulation. Background Art

[0002] During liquid-fueled engines, unsteady combustion during startup and shutdown can lead to chemical non-equilibrium. This incomplete combustion of the propellant produces intermediate products and unvaporized droplets, which form liquid-phase contaminants in the plume. These unburned droplets accumulate on the engine's inner walls, forming a liquid film. This film then breaks up at the nozzle exit, producing droplets that severely impact engine performance and the surrounding environment.

[0003] Studies have shown that temperature is a key factor affecting the above-mentioned contamination phenomenon, specifically in terms of wall temperature and liquid temperature:

[0004] Wall temperature: This influences the flow behavior, residence time, and film formation and breakup of droplets on the wall. A low wall temperature promotes droplet flow and film formation, while a high wall temperature can trigger the Leidenfrost effect, accelerating droplet evaporation and shortening contact time.

[0005] Liquid temperature: Directly changes the thermodynamic properties of the liquid (such as saturated vapor pressure and viscosity), affecting its evaporation behavior and the liquid film breakup mechanism. For example, the viscosity of ionic liquids decreases with increasing temperature, which in turn affects the flow characteristics of the liquid film.

[0006] In the existing technology, the control of nozzle wall and liquid temperature has the following deficiencies:

[0007] Limitations of nozzle temperature control: Traditional nozzles (such as conical or bell-shaped) are often made of a single material, making it difficult to independently control the temperature of the combustion chamber, throat, and expansion section. Furthermore, the curvature of the nozzle wall distorts light during optical observation, affecting the accuracy of experimental data. Furthermore, the limited internal space of miniaturized nozzles makes it difficult to integrate efficient cooling and heating devices into such a confined area using traditional processing techniques.

[0008] Lack of liquid circuit temperature control: The existing system lacks a precise control device for the temperature of the experimental medium (such as ionic liquids and hydrazine fuels), and cannot independently control the liquid temperature to decouple the influence of temperature variables on the liquid film breakup process.

[0009] Conflict between observation and structure: Although metal walls are conducive to temperature control, their opacity hinders optical observation; although transparent materials (such as acrylic) are convenient for observation, they have poor thermal stability and cannot withstand extreme temperature environments, making it difficult to balance observation needs and temperature control needs.

[0010] The existing technology has the following objective shortcomings:

[0011] Inaccurate temperature control: Existing nozzles cannot achieve independent temperature control of the combustion chamber, throat, and expansion section, and lack active regulation of the experimental medium temperature, making it difficult to systematically study the impact of temperature gradients on liquid film flow and pollutant generation.

[0012] Limited observation effects: The curved wall of traditional nozzles causes optical distortion, and the poor compatibility between metal and transparent materials makes it impossible to perform clear multi-directional observations at extreme temperatures.

[0013] Low processing feasibility: The microchannel processing in the miniaturized nozzle is difficult. Traditional processes make it difficult to integrate efficient cooling (such as liquid nitrogen) and heating (such as resistance wire) devices in a limited space, which limits the temperature control accuracy and range.

[0014] In response to the deficiencies in temperature control, observation effect and processing feasibility in the existing technology, the present invention aims to provide a spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment. The nested pipelines are used to achieve precise adjustment of the temperature of the experimental medium, and the spliced metal-insulation-acrylic structure is used to achieve zoned temperature control and multi-directional optical observation of the nozzle. This solves the problems of difficult decoupling of temperature variables, unclear observation and complex processing in the existing technology, and provides a reliable experimental platform for in-depth research on the liquid phase pollution mechanism of plumes. Summary of the Invention

[0015] The object of the present invention is to provide a spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature regulation to solve the problems raised in the above background technology.

[0016] To solve the above technical problems, the present invention provides a spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment, comprising:

[0017] Temperature-controlled nozzles, nested temperature-controlled liquid pipes, solenoid valves, and central computers;

[0018] The temperature control nozzle includes a nozzle assembly flange, a nozzle metal side wall surface, a nozzle heat insulation layer and a nozzle acrylic front plate. The nozzle metal side wall surface and the nozzle acrylic front plate are spliced and connected through the nozzle heat insulation layer.

[0019] The nested temperature-controlled liquid pipeline includes a central liquid pipeline, a heat conductor pipeline surrounding the central liquid pipeline, and a liquid nitrogen pipeline. The heat conductor pipeline and the liquid nitrogen pipeline optimize the volume ratio of the cooling and heating functions through heat transfer power calculation. The metal side wall of the nozzle is provided with a thermocouple sheet, a liquid nitrogen groove, and a metal wire groove. The thermocouple sheet is used to monitor the wall temperature of the nozzle combustion chamber, throat, and expansion section. The liquid nitrogen groove and the metal wire groove are staggered to control the temperature of the metal side wall of the nozzle.

[0020] The central computer is used to receive temperature data of the thermocouple and feedback-control the liquid nitrogen flow of the nested temperature-controlled liquid pipeline and the heating power of the heat conductor pipeline.

[0021] Furthermore, the nozzle assembly flange includes a sealing rubber ring, a flange fixing connection hole, a gas inlet and a limit hole;

[0022] The sealing rubber ring is set at the connection between the nozzle assembly flange and the front end pipeline.

[0023] The flange fixing connection hole is used to realize the sealed connection between the temperature control nozzle and the external vacuum chamber through bolts;

[0024] The gas inlet is used to introduce an external gas source to form a flow field in the nozzle;

[0025] The limiting holes are used to position the nozzle acrylic front plate during assembly.

[0026] Furthermore, independent liquid nitrogen tanks and metal wire tanks are provided on the metal sidewalls of the nozzle corresponding to the combustion chamber, throat and expansion section respectively;

[0027] The liquid nitrogen tank is welded to the liquid nitrogen tank cover to form a closed liquid nitrogen loop channel. The wire groove is an M-shaped groove for embedding the metal wire to achieve wall heating.

[0028] Thermocouples are provided with at least one measuring point on the metal walls of the combustion chamber, throat and expansion section respectively to generate temperature gradient data of the nozzle metal side wall.

[0029] Furthermore, in the nested temperature-controlled liquid pipeline, two heat conductor pipelines are provided and four liquid nitrogen pipelines are provided;

[0030] The liquid nitrogen pipeline is evenly distributed in a ring shape, and any two opposite liquid nitrogen pipeline inlets are connected at the end of the pipeline and closed together to form a liquid nitrogen loop;

[0031] A resistance wire is attached to the inner wall of the hot wire pipeline, and the experimental medium in the central liquid pipeline is heated by the thermal effect of electric current.

[0032] Furthermore, the nozzle insulation layer is made of polyimide foam material, and the nozzle metal side wall, the nozzle insulation layer and the nozzle acrylic front plate are tightly connected by a bolt and nut structure passing through the M bolt hole. The nozzle insulation layer is used to block heat transfer between the nozzle metal side wall and the nozzle acrylic front plate.

[0033] Furthermore, a Laval profile airflow channel is processed in the middle of the acrylic front plate of the nozzle, and the Laval profile airflow channel includes a contraction section, a throat section and an expansion section;

[0034] The connecting surfaces on both sides of the nozzle acrylic front plate are fixed to the nozzle metal side wall surface and the nozzle insulation layer by bolts, and the bottom adhesive surface is used to bond the nozzle acrylic side plate to form a transparent observation window.

[0035] Furthermore, the central computer collects data from the thermocouples on the nested temperature-controlled liquid pipelines and the metal side walls of the nozzle in real time, generates a real-time temperature gradient diagram, and uses the PID algorithm to adjust the valve opening of the liquid nitrogen pipeline and the current of the hot wire pipeline for closed-loop control of the experimental medium temperature and the nozzle wall temperature.

[0036] Furthermore, the liquid nitrogen tank on the metal side wall of the nozzle adopts a splicing processing technology. A complete channel is formed by milling a semi-open liquid nitrogen tank on the metal side wall of the nozzle and welding the liquid nitrogen tank cover. The width of the liquid nitrogen tank is 1.5-3mm, which is used for high-precision cooling of the metal side wall of the nozzle.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. Multi-zone independent temperature control and extreme temperature simulation:

[0039] The present invention incorporates independent liquid nitrogen tanks and wire troughs in the combustion chamber, throat, and expansion section of the nozzle's metal sidewalls. Through real-time feedback from thermocouples and closed-loop control by a central computer, independent temperature regulation is achieved in these three zones. This allows for simulation of extreme environments with gradient temperature differences up to 500°C (e.g., 500°C in the combustion chamber, 0°C in the throat, and -100°C in the expansion section). Compared to the temperature control limitations of single-material nozzles in existing technologies, this invention improves the temperature control accuracy of each zone to ±2°C through a spliced structure and staggered cooling / heating units. This provides precise thermal boundary conditions for studying the flow, fragmentation, and vaporization mechanisms of liquid films at varying wall temperatures.

[0040] 2. Precise control of liquid circuit temperature and variable decoupling:

[0041] The nested temperature-controlled liquid pipeline adopts a ring-shaped nested structure of 2 hot wire pipelines + 4 liquid nitrogen pipelines. The cooling / heating volume ratio is optimized by heat transfer power calculation (liquid nitrogen pipeline accounts for 60%, hot wire pipeline accounts for 40%), and precise control of the temperature of experimental media (such as ionic liquids and hydrazine fuels) is achieved (control error ≤±1.5℃). The liquid nitrogen pipeline adopts a loop design with relative pipe openings to avoid dead volume and improve cooling efficiency; the inner wall of the hot wire pipeline is attached with a resistance wire, and the contact area is increased through an M-shaped metal wire groove, which significantly improves the uniformity of the liquid temperature. This design can independently adjust the liquid temperature (20℃~200℃), decouple the influence of temperature variables on thermodynamic properties such as liquid viscosity and saturated vapor pressure, and provide controllable experimental conditions for studying the temperature-dominated liquid film breakup mechanism.

[0042] 3. Splicing structure improves processing feasibility and temperature control efficiency:

[0043] The liquid nitrogen tank on the metal side wall of the nozzle adopts a splicing processing technology. By milling a semi-open tank body and welding the liquid nitrogen tank cover, a high-precision liquid nitrogen channel with a width of 1.5-3mm is realized in a narrow space, solving the problem that traditional processes are difficult to process micro channels. At the same time, the M-shaped metal wire groove and the liquid nitrogen tank are staggered to achieve efficient heating and cooling in the same area, avoiding temperature control blind spots and increasing the wall temperature response speed by more than 30%. The nozzle insulation layer is made of polyimide foam material. The metal side wall of the nozzle, the nozzle insulation layer and the acrylic front plate of the nozzle are tightly connected by a bolt and nut structure that passes through the M3 bolt hole. Under the test conditions where the temperature difference between the metal side wall of the nozzle and the acrylic plate is 100°C and the thickness of the insulation layer is 5mm, the nozzle insulation layer can effectively block the heat transfer between the metal side wall of the nozzle and the acrylic front plate of the nozzle. The heat flux is tested to be ≤5W / m 2 , which not only ensures the extreme temperature environment of the metal wall, but also protects the transparent observation components from being damaged by high temperature.

[0044] 4. Multi-directional optical observation and flow field visualization:

[0045] The temperature-controlled nozzle utilizes a "metal-insulation-acrylic" splicing structure. The acrylic front and side panels form a transparent observation window. Combined with a rectangular cross-section (unlike traditional conical nozzles), this eliminates optical distortion caused by wall curvature and provides a clear viewing angle of 180° or more. The supersonic flow field (Mach numbers 2.5-3.0) and liquid film breakup process within the Laval profile flow channel are recorded in real time using a high-speed camera. Combined with thermocouple temperature gradient data, this allows for visual quantitative analysis of droplet-wall interactions, providing intuitive experimental evidence for plume contamination mechanism research.

[0046] 5. System integration and experimental operability:

[0047] The central computer uses a PID algorithm to adjust the liquid nitrogen flow rate and the current of the hot wire in real time, forming a closed-loop temperature control. This significantly improves system stability and reduces the temperature fluctuation range to ≤±2°C. The modular design of the nested pipes and nozzles supports the rapid replacement of experimental media (such as ethanol and ionic liquids) and the adjustment of temperature control parameters. By changing the pipe material (such as stainless steel and polytetrafluoroethylene), it can adapt to corrosive liquids and has a wide range of applications. Compared with existing technologies, the spliced structure and integrated temperature control system of the present invention shorten experimental preparation time by more than 50%, significantly improving research efficiency and data reproducibility.

[0048] In summary, the present invention achieves precise independent control of the nozzle wall and experimental medium temperature, multi-directional optical observation, and efficient experimental operation through the organic combination of structural innovation and temperature control technology, providing a groundbreaking experimental platform for the study of liquid engine plume pollution mechanisms, and has significant scientific research and engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic diagram of a spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment according to the present invention;

[0050] Figure 2 This is a schematic diagram of the overall structure of the spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment according to the present invention;

[0051] Figure 3 Schematic diagram of the temperature-controlled nozzle in the spliced temperature-controlled rectangular nozzle observation system with nested liquid circuit temperature adjustment according to the present invention;

[0052] Figure 4 This is a schematic diagram of the nozzle assembly flange structure in the spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment of the present invention;

[0053] Figure 5 This is a schematic diagram of the main structure of the nozzle metal side wall in the spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment of the present invention;

[0054] Figure 6 This is a schematic diagram of the structure of the liquid nitrogen tank cover in the spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment of the present invention;

[0055] Figure 7 Schematic diagram of the nozzle insulation layer structure in the spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment according to the present invention;

[0056] Figure 8 Schematic diagram of the main structure of the gas-liquid flow channel in the spliced temperature-controllable rectangular nozzle observation system with nested liquid path temperature adjustment of the present invention;

[0057] Figure 9 This is a schematic diagram of the nested pipe top structure in the spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment of the present invention;

[0058] Figure 10 This is a schematic diagram of the nested pipe bottom structure in the spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment of the present invention. DETAILED DESCRIPTION

[0059] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0060] See also Figures 1-10 , the present invention provides a technical solution:

[0061] See Figures 1-10 As shown, an embodiment of a spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature adjustment:

[0062] 1. Overall system structure:

[0063] The "jointed temperature-controllable rectangular nozzle observation system with nested liquid path temperature adjustment" provided in this embodiment is as follows: Figure 1 and Figure 2 As shown, the system mainly includes a temperature-controlled nozzle 1, a nested temperature-controlled liquid pipeline 2, a solenoid valve 3, and a central computer control system. The temperature-controlled nozzle 1 precisely controls the temperature of the flow field within the nozzle, while the nested temperature-controlled liquid pipeline 2 precisely regulates the temperature of the experimental medium. The two are connected via the solenoid valve 3 and pipelines to form a gas-liquid coupled temperature-controlled observation system.

[0064] 2. Temperature control nozzle structure and implementation method:

[0065] (1) Nozzle mounting flange 101:

[0066] like Figure 4 As shown, the nozzle assembly flange 101 is a ring-shaped metal structure with a gas inlet 10103 in the center for connecting to the front-end gas supply pipeline. Evenly distributed flange fixing holes 10102 are located along the flange edge. Bolts seal the flange with the vacuum chamber through-chamber flange. A sealing rubber ring 10101 is installed at the connection to ensure a tight gas flow. A stopper hole 10104 is located below the flange to position the nozzle acrylic front plate 105 and ensure assembly accuracy.

[0067] (2) Nozzle metal side wall surface 102:

[0068] like Figure 5 As shown, the metal side wall 102 is a rectangular parallelepiped structure, and independent temperature control units are set corresponding to the combustion chamber, throat, and expansion section. Each temperature control unit includes:

[0069] Liquid nitrogen tank 10203 and liquid nitrogen tank cover 103: A semi-open liquid nitrogen tank 10203 is milled inside the metal side wall, and the slot is fixed to the liquid nitrogen tank cover 103 by welding to form a closed liquid nitrogen circuit channel. Two butt joints are set on the liquid nitrogen tank cover 103, which serve as the liquid nitrogen inlet and outlet respectively. Figure 6 Liquid nitrogen flows in from the inlet, passes through the liquid nitrogen tank, and then flows out from the outlet to achieve cooling of the metal wall.

[0070] Metal wire slot 10204: It is an M-shaped slot, staggered with the liquid nitrogen slot, and a metal wire (such as nickel-chromium alloy wire) is embedded in the slot. The metal wire is connected to an external power supply through a wire, and when powered on, it uses the Joule effect to heat the wall. Figure 5 The M-shaped design of the wire trough increases the contact area between the wire and the wall, improving heating efficiency.

[0071] Thermocouple pieces 10202: Five thermocouple pieces 10202 are attached to the metal walls of the combustion chamber, throat, and expansion section to monitor the temperature of each area in real time. The data is transmitted to the central computer via wires.

[0072] (3) Nozzle insulation layer 104:

[0073] like Figure 7 As shown, thermal insulation layer 104 is made of polyimide foam, 5 mm thick, and has M3 bolt holes 10401. It is bolted to the metal sidewall 102, the nozzle acrylic front plate 105, and the rear plate. The thermal insulation layer, located between the metal sidewall and the acrylic material, blocks heat transfer and protects the acrylic plate from damage due to high temperatures.

[0074] (4) Nozzle acrylic front plate 105 and side plates 106:

[0075] like Figure 3 and Figure 8 As shown, the center of the acrylic front panel 105 is machined with a Laval-shaped airflow channel 10502, consisting of a contraction section, a throat, and a divergence section. Gas enters the channel through the gas inlet 10103, forming a supersonic flow field. Connecting surfaces 10501 are provided on both sides of the front panel, secured to the metal sidewalls 102 and the thermal insulation layer 104 via bolts. An adhesive surface 10503 is provided on the bottom, which is bonded to the nozzle acrylic side panel 106 with strong glue, forming a transparent observation window for lateral and forward optical observation.

[0076] 3. Structure and implementation of nested temperature-controlled liquid pipeline 2:

[0077] like Figure 9 and Figure 10 As shown, the nested pipe is a multi-layer coaxial sleeve structure, including:

[0078] Central liquid pipeline: inner diameter is 8mm, used to transport experimental media (such as ionic liquids).

[0079] Heating wire pipe 201: 2 in total, surrounding the central pipe, with an inner diameter of 3mm and a resistance wire (resistivity 1.1Ω·mm) attached to the inner wall 2 / m), the liquid in the central pipe is heated by electric current, and the heating power is calculated by the formula \(P=I 2 R\) calculation to ensure temperature uniformity.

[0080] Liquid nitrogen lines 202: Four in total, evenly distributed outside the heat conductor line, have an inner diameter of 4mm. Liquid nitrogen enters through any two opposing pipe openings and returns through the adjacent pipe opening at the end of the pipe through a connecting structure, forming a closed loop to cool the central pipe. By calculating the heat transfer power, the volume ratio of the liquid nitrogen line and the heat conductor line is optimized (60% for liquid nitrogen and 40% for heat conductor) to ensure maximum temperature control efficiency.

[0081] 4. System workflow:

[0082] (1) Temperature control initialization:

[0083] Nozzle Temperature Control: A central computer presets target temperatures for the combustion chamber, throat, and expansion section (e.g., 500°C for the combustion chamber, 0°C for the throat, and -100°C for the expansion section), activating the wire heating system and liquid nitrogen delivery system. Thermocouples 10202 provide real-time feedback on the temperature of each zone. The central computer uses a PID algorithm to adjust the heating power and liquid nitrogen flow until the target temperature is reached and stabilized.

[0084] Liquid temperature control: The experimental medium enters the nested pipe from the storage tank through the solenoid valve 3. The central computer controls the hot wire current or liquid nitrogen flow according to the preset liquid temperature (such as 25℃~150℃), and monitors the pipe wall temperature through the thermocouple to achieve precise regulation of the liquid temperature.

[0085] (2) Gas-liquid coupling experiment:

[0086] The gas enters the Laval-type airflow channel 10502 through the gas inlet 10103 of the nozzle mounting flange 101, forming a supersonic flow field (Mach number 2.5 to 3.0).

[0087] The temperature-controlled experimental medium is injected into the nozzle from the liquid inlet 10201 of the metal side wall 102, forming a liquid film on the wall surface, which is broken into droplets by the shear force of the airflow.

[0088] The acrylic front plate 105 and side plates 106 provide a transparent observation field. The liquid film flow, breakup and droplet generation process are recorded by a high-speed camera. Combined with the thermocouple temperature data, the influence of different wall temperatures (low temperature -100℃ to high temperature 500℃) and liquid temperatures (20℃ to 200℃) on the contamination mechanism is analyzed.

[0089] (3) Real-time feedback adjustment:

[0090] The central computer collects thermocouple data from the nested pipes and nozzle metal side walls in real time and generates a temperature gradient map (such as Figure 1 When the measured temperature deviates from the preset value by more than ±2°C, the liquid nitrogen valve opening or the hot wire current is automatically adjusted to achieve closed-loop temperature control and ensure stable experimental conditions.

[0091] 5. Implementation method:

[0092] (1) Nested pipeline temperature control integration:

[0093] The cooling and heating functions are integrated through the ring layout of 2 heat conductor pipelines and 4 liquid nitrogen pipelines. Liquid nitrogen circuit design (such as Figure 10 Bottom interconnecting structure) to avoid dead volume and improve cooling efficiency; M-shaped contact of heat conductor pipes (such as Figure 5 The metal wire slot increases the heating area and the temperature uniformity error is ≤±1.5℃.

[0094] (2) Spliced nozzle processing technology:

[0095] The liquid nitrogen tank and the liquid nitrogen tank cover on the metal side wall are separated and processed, and then connected by welding (such as Figure 6 ), solves the problem of small channels being difficult to form in traditional processing, and realizes a high-precision liquid nitrogen channel with a groove width of 1.5mm and a cooling accuracy of ±2℃. The bolt connection between the insulation layer and the acrylic plate (such as Figure 7 Bolt holes) ensure structural strength and isolate heat conduction (heat flux ≤ 5W / m 2 ).

[0096] (3) Three-zone independent temperature control:

[0097] Independent liquid nitrogen tanks and metal wire tanks are set in the combustion chamber, throat, and expansion section respectively. Through thermocouple feedback (5 measuring points in each area), the temperature difference between each area can reach 500°C (such as 500°C in the combustion chamber, 0°C in the throat, and -100°C in the expansion section), meeting the needs of extreme temperature gradient simulation.

[0098] 6. Summary:

[0099] This embodiment achieves the following through the above structure and control method:

[0100] Temperature control accuracy: nozzle temperature control error of each area ≤ ± 2 ° C, liquid temperature control error

[0101] ≤±1.5℃, gradient temperature difference can reach 500℃.

[0102] Observation performance: The rectangular nozzle cross-section (width and height 20mm × 15mm) eliminates optical distortion caused by curvature, and the acrylic transparent component provides a ≥180° observation angle, meeting the measurement requirements of high-speed photography and laser particle size analyzers.

[0103] Scope of application: Compatible with various media such as ethanol, hydrazine fuel, ionic liquid, etc. By replacing the nested pipe material (such as stainless steel, polytetrafluoroethylene), it can adapt to corrosive liquids and has a wide range of applications.

[0104] In summary, this embodiment achieves precise control of the nozzle wall and experimental medium temperature through the innovative design of nested liquid circuit temperature control and spliced nozzle structure, providing a reliable experimental platform for studying the plume liquid phase pollution mechanism.

Claims

1. A spliced temperature-controllable rectangular nozzle observation system with nested liquid temperature control, characterized in that: include: Temperature control nozzle (1), nested temperature control liquid pipeline (2), solenoid valve (3) and central computer; The temperature-controlled nozzle (1) comprises a nozzle assembly flange (101), a nozzle metal side wall surface (102), a nozzle heat insulation layer (104) and a nozzle acrylic front plate (105), wherein the nozzle metal side wall surface (102) and the nozzle acrylic front plate (105) are spliced and connected via the nozzle heat insulation layer (104); The nested temperature-controlled liquid pipeline (2) comprises a central liquid pipeline, a heat conductor pipeline (201) and a liquid nitrogen pipeline (202) surrounding the central liquid pipeline. The heat conductor pipeline (201) and the liquid nitrogen pipeline (202) optimize the volume ratio of the cooling and heating functions by heat transfer power calculation. A thermocouple sheet (10202), a liquid nitrogen tank (10203) and a metal wire tank (10204) are provided on the nozzle metal side wall (102). The thermocouple sheet (10202) is used to monitor the wall temperature of the nozzle combustion chamber, throat and expansion section. The liquid nitrogen tank (10203) and the metal wire tank (10204) are staggered to control the temperature of the nozzle metal side wall (102). The central computer is used to receive temperature data of the thermocouple (10202) and feedback control the liquid nitrogen flow of the nested temperature-controlled liquid pipeline (2) and the heating power of the hot wire pipeline (201).

2. The spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature control according to claim 1, characterized in that: The nozzle assembly flange (101) comprises a sealing rubber ring (10101), a flange fixing connection hole (10102), a gas inlet (10103) and a limiting hole (10104); The sealing rubber ring (10101) is arranged at the connection between the nozzle assembly flange (101) and the front end pipeline. The flange fixing connection hole (10102) is used to realize a sealed connection between the temperature control nozzle (1) and the external vacuum chamber body through bolts; The gas inlet (10103) is used to introduce an external gas source to form a flow field in the nozzle; The limiting hole (10104) is used to position the nozzle acrylic front plate (105) during assembly.

3. The spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature control according to claim 1, characterized in that: The nozzle metal side wall surface (102) is provided with independent liquid nitrogen grooves (10203) and metal wire grooves (10204) corresponding to the combustion chamber, throat and expansion section respectively; The liquid nitrogen tank (10203) is welded to the liquid nitrogen tank cover (103) to form a closed liquid nitrogen loop channel, and the metal wire tank (10204) is an M-shaped groove for embedding the metal wire to achieve wall heating; The thermocouple piece (10202) is provided with at least one measuring point on the metal wall surfaces of the combustion chamber, the throat and the expansion section respectively, so as to generate temperature gradient data of the nozzle metal side wall surface (102).

4. The spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature control according to claim 1, characterized in that: In the nested temperature-controlled liquid pipeline (2), two heat conductor pipelines (201) are provided, and four liquid nitrogen pipelines (202) are provided; The liquid nitrogen pipelines (202) are evenly distributed in a ring shape, and any two opposite inlets of the liquid nitrogen pipelines (202) are connected at the ends of the pipelines and are closed together to form a liquid nitrogen loop; A resistance wire is attached to the inner wall of the heat conductor pipeline (201), and the experimental medium in the central liquid pipeline is heated by the thermal effect of the electric current.

5. The spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature control according to claim 1, characterized in that: The nozzle heat insulation layer (104) is made of polyimide foam material. The nozzle metal side wall surface (102), the nozzle heat insulation layer (104) and the nozzle acrylic front plate (105) are tightly connected by a bolt and nut structure penetrating an M3 bolt hole (10401). The nozzle heat insulation layer (104) is used to block heat transfer between the nozzle metal side wall surface (102) and the nozzle acrylic front plate (105).

6. The spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature control according to claim 1, characterized in that: A Laval profile airflow channel (10502) is processed in the middle of the nozzle acrylic front plate (105), and the Laval profile airflow channel (10502) includes a contraction section, a throat section, and an expansion section; The two side connecting surfaces (10501) of the nozzle acrylic front plate (105) are fixed to the nozzle metal side wall surface (102) and the nozzle insulation layer (104) by bolts, and the bottom adhesive surface (10503) is used to bond the nozzle acrylic side plate (106) to form a transparent observation window.

7. The spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature control according to claim 1, characterized in that: The central computer collects data from the thermocouples (10202) of the nested temperature-controlled liquid pipeline (2) and the metal side wall (102) of the nozzle in real time, generates a real-time temperature gradient diagram, and adjusts the valve opening of the liquid nitrogen pipeline (202) and the current of the heat conductor pipeline (201) through a PID algorithm for closed-loop control of the experimental medium temperature and the nozzle wall temperature.

8. The spliced temperature-controllable rectangular nozzle observation system with nested liquid circuit temperature control according to claim 1, characterized in that: The liquid nitrogen groove (10203) on the nozzle metal side wall (102) adopts a splicing processing technology, by milling a semi-open liquid nitrogen groove (10203) on the nozzle metal side wall (102) and welding a liquid nitrogen groove cover (103) to form a complete channel. The width of the liquid nitrogen groove (10203) is 1.5-3 mm, and is used for high-precision cooling of the nozzle metal side wall (102).

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