Optical visualization test device suitable for transverse jet mixing characteristic research under different conditions

Abstract

The invention discloses an optical visualization test device suitable for transverse jet mixing characteristic research under different conditions. The optical visualization test device mainly comprises an air inlet diffusion section, a main body mixing section and an exhaust structure section. The main body mixing section is of a double-layer structure with an inner-layer main temperature bearing function and an outer-layer main pressure bearing function, an independent cooling cavity is formed between the flame tube and the cartridge receiver, replaceable flat straight flow channel or contraction flow channel installation bases are arranged on the upper wall face and the lower wall face of the flame tube, and multiple functional modules such as main combustion holes and cooling gas film flow channels are integrated. Each wall surface is provided with an optical glass window, and multi-path laser incidence and image acquisition are supported. Blended gas enters the blending holes through the gas collection tank and the flow uniformizing plate, transverse jet flow and main flow blending is formed, and the device is suitable for visual measurement under different rotational flow intensities, cooling conditions and wall surface structures. And the exhaust section is provided with a spraying and water jacket cooling system, so that the exhaust temperature can be effectively controlled. The device is flexible in structure, adjustable in parameter and suitable for combustion chamber jet mixing mechanism research and optical measurement verification.

Description

Technical Field

[0001] The present invention belongs to the technical field of aero-engine combustion chambers, and relates to analysis of combustion chamber transverse jet mixing characteristics and optical visualization measurement technology. It mainly relates to an optical visualization test device suitable for studying transverse jet mixing characteristics under different conditions, which can realize multi-structure combination, high-temperature and high-pressure operation and high-precision non-contact flow field observation. Background Art

[0002] The combustion chamber of an aircraft engine is a core hot-end component. Its internal flow and mixing characteristics directly determine combustion efficiency, emissions performance, and turbine inlet temperature uniformity. In a typical annular combustor structure, the flame tube is typically divided into a primary combustion zone and a mixing zone. Air in the annular cavity enters each functional zone through primary combustion holes, cooling holes, and mixing holes. The primary combustion holes partially limit the axial length of the recirculation zone while the remaining portion flows to the intermediate / mixing zone. The mixing holes regulate the combustor outlet temperature quality by providing an appropriate proportion of cooling air. As aircraft engines develop towards high thrust-to-weight ratios and low emissions, the swirl combustion process at the combustor head consumes over 70% of the total intake air, leading to insufficient mixing air and uneven turbine inlet temperatures. This can easily lead to component thermal fatigue, reduced life, and localized overheating. Therefore, it is urgent to study the cross-jet mixing characteristics under different structural and aerodynamic conditions. This study will clarify the outlet temperature and velocity distribution of low-mixed combustors under different operating conditions and provide guidance for the design of new mixing holes for combustors.

[0003] Currently, research on the mixing characteristics of transverse jets in combustion chambers primarily relies on traditional measurement methods or optical measurement techniques. However, traditional measurement methods (such as placing a temperature rake or thermocouple array at the combustion chamber outlet) can distort the results due to interference with the flow field. Furthermore, sensors placed at the outlet can only reflect the overall mixing effect and cannot reveal key flow mechanisms such as local flow, jet penetration, vortex generation and decay. Optical measurement methods, such as Planar Laser-Induced Fluorescence (PLIF) and non-contact optical measurement methods based on particle image velocimetry (PIV), avoid these shortcomings and can achieve transient measurements of velocity fields, temperature fields, and component distributions. They offer significant advantages such as high precision, high resolution, and non-invasiveness. However, optical measurement techniques place high demands on the optical accessibility of the experimental device, requiring the test device to have a good window design to ensure laser incidence and signal acquisition.

[0004] In the prior art, for example, a three-head combustion chamber structure with adjustable main combustion holes and mixing holes, as disclosed in Chinese patent CN215411978U, uses a replaceable swirler head mounting plate and replaceable main combustion hole plate to change the head spacing ratio, applies sealant to the mixing hole sealing plate to adjust the mixed gas volume, uses independent air supply from the main combustion hole, mixing hole, and intake casing, and provides optical measurements with windows on the left and right sides and behind the test piece. Overall, this solution can meet the requirements for experimental research on cross-jet mixing characteristics under certain conditions. However, this solution still has the following problems:

[0005] It is impossible to conduct tests on the transverse jet mixing characteristics under the conditions of contracting flow channel and wall cooling air; the air intake casing, flame tube main body and exhaust casing are single-layer structures. If tests are conducted under high temperature conditions, the test pieces cannot be effectively cooled. If tests are conducted under higher pressure, only one layer of glass window bears the pressure, and the risk of fragmentation due to uneven stress is higher; no uniform flow plate is set at the mixing hole air intake casing. If the incoming flow is uneven, the amount of gas entering each mixing hole will be quite different; if you want to shoot the spanwise cross-section jet trajectory, the laser must enter from the rear window, but the rear window is far away from the mixing hole, which may cause obvious laser attenuation and is not conducive to shooting; on the other hand, the flow length of the flame tube side wall window is not long enough, and it is impossible to fully shoot the downstream trajectory of the spanwise cross-section of the mixing hole jet.

[0006] In summary, the existing transverse jet mixing characteristics test device has significant deficiencies in complex flow channel simulation, high temperature and high pressure tolerance, gas volume uniformity control and optical measurement accuracy. Therefore, how to design a transverse jet mixing test device that is suitable for a variety of structures and boundary conditions, has high temperature and high pressure resistance, and has good optical visualization performance is a technical problem that needs to be solved urgently. Summary of the Invention

[0007] (1) Purpose of the invention

[0008] In view of the above-mentioned defects and shortcomings of the prior art, the present invention aims to provide an optical visualization test device suitable for the study of transverse jet mixing characteristics under different conditions. A modular frame structure is adopted to realize the flexible replacement of various wall boundary conditions such as straight flow channels, contraction flow channels and cooling air film flow channels. The uniformity of the multi-porous jet air supply is ensured by the uniform flow plate structure of the mixing air collecting box, and the overall high temperature and high pressure resistance is improved by combining the internal and external double-layer structure design. At the same time, multiple viewing windows are arranged on the four sides of the flame tube and near the mixing area, which significantly optimizes the laser incident path and shooting accuracy, meets the needs of multi-angle high-precision non-contact optical measurement, and thus realizes the detailed analysis of the transverse jet mixing behavior under the conditions of complex airflow organization in the combustion chamber, providing an experimental basis and technical support for the design of low-mixed combustion chambers.

[0009] (2) Technical solution

[0010] In order to achieve the purpose of the invention and solve the technical problems, the present invention adopts the following technical solutions:

[0011] An optical visualization test device suitable for studying the mixing characteristics of transverse jets under different conditions, used to simulate the transverse jet mixing behavior in an aircraft engine combustion chamber and perform non-contact optical measurements, the test device comprising at least:

[0012] The air inlet diffuser section is used to decelerate and pressurize the high-temperature and high-speed incoming air and form it into a uniform and straight high-temperature airflow. Its overall design is an expansion structure. Its inlet is connected to the external air supply system, and its outlet is connected to the downstream main mixing section. Its wall is designed to be a high-temperature resistant structure;

[0013] The main mixing section is arranged downstream of the air intake diffuser section and is used to simulate the transverse jet mixing process under various wall boundary conditions. It includes a frame-type main structure and an inlet flange plate and an outlet flange plate arranged at its front and rear ends, wherein: the frame-type main structure includes a coaxially arranged flame tube and a casing, the flame tube is formed as an inner main temperature-bearing structure, and the casing is formed as an outer main pressure-bearing structure; the flame tube and the casing are structurally designed as a cylindrical structure surrounded by four upper, lower, left and right walls, and four independent closed cooling cavities are formed between the four walls of the casing and the flame tube and the inlet and outlet flange plates at the front and rear ends, which are used to pass cooling gas to realize flame The tube is cooled on multiple sides; and optical glass windows are provided on the four walls of the casing and the flame tube for non-contact visual measurement of laser incidence and high-temperature flow fields, and provide a variety of optical measurement path options; the upper and lower walls of the flame tube are provided with replaceable flow channel mounting seats, and different flow channel mounting seats have different wall structures. The upper and lower optical glass windows of the flame tube are correspondingly arranged on the flow channel mounting seats, and the optical glass is provided with multiple mixing holes to form a mixed glass; the front end of the flame tube is provided with a head swirler mounting plate located on the inlet flange plate, on which multiple swirlers are installed, which are used to convert the upstream uniform high-temperature incoming flow into a strong swirling turbulent flow before entering the flame tube;

[0014] The exhaust structure section is used to guide the discharge of experimental exhaust gas and control the exhaust temperature. It includes an exhaust gas collecting box with a front end connected to the flame tube outlet. The upper and lower or left and right side walls of the exhaust gas collecting box are provided with exhaust channels connected to its inner cavity. The exhaust channel is provided with a high-temperature exhaust cooling structure, and the rear wall of the exhaust gas collecting box is provided with a rear optical glass window close to the outlet of the mixing section, which is used to shorten the laser incident path and reduce the attenuation of the laser during the jet measurement process.

[0015] (3) Technical effects

[0016] The present invention provides a temperature- and pressure-resistant, all-around optical visualization transverse jet test device suitable for a variety of conditions, with an easily replaceable frame design. The advantages are:

[0017] (1) The main part of this test device is designed as a frame structure, and is designed with contraction flow channel mounting seats with different contraction ratios and easy disassembly and replacement. The frame structure serves as a foundation and carries different contraction flow channel mounting seats or flat flow channel mounting seats. In addition, in front of the mixing holes on the upper and lower walls of the inner layer of the frame structure (i.e., the flame tube), this test device is provided with a cooling air film slit flow channel with adjustable gas volume, and two rows of main combustion holes that can be enabled / disabled and hedged up and down as needed, realizing the arrangement and combination of different structural conditions (main combustion holes, wall cooling gas, contraction flow channel, flat flow channel) and mixing holes with different parameters. The present invention takes into account a variety of wall conditions such as flat flow channel, contraction flow channel, cooling air film flow channel, single-sided and double-sided, and can also realize the transverse jet test under the main combustion hole intercepting the swirl.

[0018] (2) In terms of thermal structure layout, the main part of this test device adopts a full-range double-layer structure, that is, the flame tube is wrapped in the 360° of the casing, so that the inner layer (flame tube) is mainly heat-bearing and the outer layer (casing) is mainly pressure-bearing. When necessary, ventilation and cooling can be carried out between the inner and outer layers. In addition, the window glass adopts a multi-layer pressure-resistant structure, which can effectively withstand high pressure. The "inner layer-glass fiber insulation layer-outer layer" high-temperature resistant structure of the air intake section of this test device can be safely used under the incoming air of 1200K and 0.5Mpa after verification and calculation; the "inner layer is mainly heat-bearing and outer layer is mainly pressure-bearing" full-range double-layer structure of the main mixing section, as well as the annular cavity ventilation and cooling capacity, can introduce cooling gas into the annular cavity for annular cavity ventilation and cooling; in order to ensure that the exhaust temperature is lower than the maximum withstand temperature of the rear valve under high temperature conditions, the exhaust structure section has a cooling water jacket and spray water for cooling. The cooling water enters the pipe interlayer from the lowest point of the water jacket and is discharged from the highest point. The spray water is directly sprayed into the exhaust gas to remove the residual heat of the high-temperature exhaust gas to the greatest extent. The above thermal structure layout together constitutes the high temperature and high pressure resistance capabilities of this test device.

[0019] (3) This test device is equipped with uniform flow plates inside the upper and lower mixing and collecting boxes to ensure that the mixed gas enters the cavity between the outer wall of the flame tube and the casing evenly, and to prevent uneven gas volume in each hole of the porous mixing plate; in the present invention, the flame tube and the casing are opened on all four sides, and a window is opened at the rear near the upstream position, which provides a variety of options for building the optical path and is convenient for conducting optical experiments; the window adopts a multi-layer buffer structure of "thicker glass-high temperature glue-glass frame-graphite gasket" to effectively avoid fragmentation and improve pressure resistance.

[0020] (4) In order to shorten the optical path, this test device uses two upper and lower U-shaped bends to exhaust and leave space for the optical path arrangement. The laser can enter from the flame tube outlet (i.e., behind the test piece) and the glass window close to the mixing hole, or it can enter from the top of the test device downward through the glass on the casing and the mixing glass into the test area. Both methods can effectively reduce attenuation. On the other hand, this test device extends the flow length of the flame tube side wall window to ensure that the downstream scalar and vector field distribution of the mixing hole jet can be fully captured.

[0021] (5) The present invention flexibly replaces different structures as needed, demonstrating comprehensive advantages such as strong structural adaptability, flexible boundary configuration, and a rich array of measurement paths. This significantly improves the efficiency and experimental reconstruction capabilities of studying transverse jet mixing behavior under different operating conditions. Its modular experimental structure avoids the need to manufacture multiple integrated flame tubes, saving money and time, and reducing manufacturing costs and modification difficulty. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of the overall structure of the optical visualization test device of the present invention suitable for studying the mixing characteristics of transverse jets under different conditions;

[0024] Figure 2 for Figure 1 An XY plane cross-sectional view of the main part of the test piece, i.e., the main mixing section;

[0025] Figure 3 This is a schematic diagram of the upper and lower walls of the flame tube in the main mixing section of the test device. Figure 2 The upper and lower walls of the flame tube are displayed separately, providing a three-dimensional and intuitive schematic diagram of how the test device uses / disables the main combustion holes and cooling air film flow channels according to needs, as well as how to switch between the contraction flow channel and the flat flow channel.

[0026] Figure 4 for Figure 1 The YZ plane cross-sectional view of the main part of the test piece, i.e., the main mixing section, is intended to demonstrate the full range of the double-layer structure of the test piece;

[0027] Figure 5 This is the isometric view of the main part of the test device, that is, the main mixing section. Figure 4 The purpose of this combination is to demonstrate the ventilation and cooling capabilities of the cavity between the flame tube and the casing;

[0028] Figure 6 This is a schematic diagram of the structure of the multi-layer pressure-resistant glass windows on the upper and lower walls of the casing and the uniform flow plate of the mixing and collecting box. The left and right walls of the casing and the left and right walls of the flame tube have the same multi-layer pressure-resistant glass window structure.

[0029] Figure 7 This is a cross-sectional view of the multi-layer pressure-resistant glass window structure of the present invention;

[0030] Figure 8 This is a cross-sectional view of the mixing and uniform flow plate structure in the present invention;

[0031] Figure 9 Schematic diagram of the installation method of the mixed glass at the upper / lower wall of the flame tube in the present invention;

[0032] Figure 10 This is a cross-sectional view of the installation method of the mixed glass at the upper / lower wall of the flame tube in the present invention.

[0033] Description of reference numerals:

[0034] 1-Intake diffuser; 11-Diffuser outlet flange; 2-Main mixing section; 20-Mixing hole; 21-Mixing section inlet flange; 22-Mixing gas collecting box; 23-Casing upper wall glass and cover (symmetrical structure, same as the lower wall of the casing); 24-Casing upper wall glass / gas collecting box mounting base (symmetrical structure, same as the lower wall of the casing); 25-Sensor measurement hole / vent hole; 26-Sensor measurement hole / vent hole; 27-Casing right side glass mounting base (symmetrical structure, same as the left wall of the casing); 28-Casing right side glass and cover (symmetrical structure, same as the left wall of the casing); 29-Mixing section outlet flange; 3 - Exhaust structure section; 31 - Exhaust section inlet flange; 32 - Rear view window and cover; 33 - Sensor measurement hole / air vent; 34 - Lower cooling water jacket; 35 - Upper cooling water jacket; 36 - Spray cooling water inlet; 37 - Exhaust section outlet flange; 210 - Head swirler; 211 - Swirler mounting plate (the structure shown has slit 212, the other structure does not); 212 - Slit channels for supplying air to main combustion holes (one each in the upper and lower rows); 213 - Main combustion holes (one row each in the upper and lower rows); 214 - Main combustion hole chamber baffles (one each in the upper and lower rows); 215 - Cooling air slit flow channel; 216 - Cooling air flow channel outlet baffle; 217-Flat straight channel mounting seat (the structure shown in the figure can form a cooling air film; the other structure does not have 215-216 and does not form a cooling air film); 218-Contraction channel mounting seat (different contraction ratios can be designed according to needs); 219-Contraction channel mounting cover; 220-Upper wall of the flame tube; 221-Lower wall of the flame tube; 222-Upper wall of the casing; 223-Lower wall of the casing; 224-Right wall of the casing; 225-Left wall of the casing; 226-Left wall of the flame tube; 227-Right wall of the flame tube; 228-Airflow outlet of the annular cavity (between the flame tube and the casing); 229-Casing upper wall glass and gas collecting box installation Seat; 230-lower graphite gasket; 231-lower glass frame; 232-quartz glass; 233-upper glass frame; 234-upper graphite gasket; 235-window cover; 236-flow uniform plate; 237-gas collecting box NPT connector; 238-lower gasket; 239-mixed glass (there are several pieces of glass with different pore diameters, different pore arrangements, and different pore shapes, which can be replaced as needed; it should be noted that the glass shown in the figure is suitable for the size of the flat flow channel mounting seat, and the glass suitable for the contraction flow channel mounting seat is only different in size, and the rest is the same, so it is not repeated); 240-upper gasket; 241-mixed glass cover. DETAILED DESCRIPTION

[0035] The present invention aims to provide an optical visualization test device suitable for studying the mixing characteristics of transverse jets under different conditions, which is used to simulate the mixing behavior of transverse jets in the combustion chamber of an aircraft engine and perform non-contact optical measurements. In order to make the purpose, technical solutions and advantages of the present invention clearer, the following will be combined with the appended drawings of the present invention to illustrate the optical visualization test device. Figures 1 to 10 , clearly and completely describing the technical solutions of the present invention. Obviously, the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0036] Figure 1 The overall structure diagram of the optical visualization test device of the present invention is suitable for studying the mixing characteristics of transverse jets under different conditions. Figure 1 As shown, the test apparatus of the present invention comprises three main functional units: an intake diffuser section 1, a main mixing section 2, and an exhaust structure section 3. These units are connected by flanges to form a sealed, high-temperature test environment. The intake diffuser section 1 is connected to the mixing section inlet flange 21 at the front end of the main mixing section 2 via the diffuser section outlet flange 11 at its rear end, ensuring a stable transition of high-temperature airflow. The main mixing section 2 is connected to the exhaust section inlet flange 31 of the exhaust structure section 3 via the mixing section outlet flange 29 at its rear end, forming an integrated flow channel.

[0037] from Figure 1 As can be seen from the structural arrangement, a sufficiently long optical glass window 28 is provided on the right side of the receiver. This window is arranged along the flow direction and has sufficient flow length reserved to provide sufficient viewing angle coverage for a high-speed camera or laser measurement system, allowing the complete jet trajectory to be captured. Furthermore, the short flow distance between the center of the mixing hole 20 and the rear window 32 of the present invention effectively shortens the optical path and reduces the path attenuation of the laser during mainstream propagation. This helps to improve the incident laser energy density and image signal-to-noise ratio, making it particularly suitable for high-precision non-contact measurements such as PLIF and PIV.

[0038] In this embodiment of the present invention, the intake diffuser section 1 utilizes an integral modular design, a removable and replaceable structure comprising multiple replaceable diffuser flow modules. Different diffuser flow modules have varying diffusion angles and length ratios, with the diffusion angle range preferably set between 5 and 25 degrees to cover typical axial pre-swirl and non-swirl combustion chamber inlet conditions. The inner wall of each diffuser flow module is smoothed and equipped with a streamlined flow guide transition structure to minimize boundary layer separation and improve the uniformity of the mainstream flow field. This modular diffuser section structure not only facilitates replacement of the diffuser section required for different test conditions but also enables systematic research on jet mixing behavior under varying inlet Reynolds numbers, Mach numbers, and swirl development conditions.

[0039] The intake diffuser section 1 as a whole adopts a multi-layer high-temperature resistant wall structure, which specifically includes a main thermal-bearing layer of a metal pipe located on the inside, a high-temperature glass fiber or alumina ceramic fiber insulation layer wrapped on the outside, and a metal shell pressure-bearing layer located on the outermost side and bearing the structural pressure. The multi-layer structure is continuously arranged along the flow direction, and a sealed thermal insulation interface is formed between each layer to effectively reduce heat conduction and structural thermal stress concentration. The inner metal pipe material is made of high-temperature resistant alloy or ceramic-coated steel, which can withstand high-temperature incoming flow erosion of not less than 1200K. The shell structure is designed to have a supporting function and can maintain structural stability under a maximum total intake pressure of not less than 0.5MPa.

[0040] The diffuser outlet is equipped with a diffuser outlet flange 11, which is threaded and sealed to the inlet flange 21 of the downstream mixing section via high-strength fasteners. A high-temperature-resistant sealing gasket, preferably made of high-performance sealing materials such as graphite-reinforced composite gaskets or spiral wound gaskets, is installed at the connection interface to effectively prevent gas leakage and structural loosening in the connection area due to high temperature gradients and thermal expansion, ensuring the long-term sealing reliability and connection structural security of the test device under high-temperature, high-speed airflow conditions.

[0041] In the embodiment of the present invention, Figure 2 、 Figure 4 、 Figure 5 As shown, the main mixing section 2 in the present invention is arranged downstream of the intake diffuser section 1. It is the core experimental area of ​​the experimental device for studying the transverse jet mixing process, simulating the jet mixing behavior under various typical boundary conditions in the combustion chamber of an aircraft engine, and being compatible with different optical measurement paths and laser imaging requirements.

[0042] In general, the main mixing section 2 includes a frame-type main structure and an inlet flange plate 21 and an outlet flange plate 29 arranged at its front and rear ends. The frame-type main structure includes a coaxially arranged flame tube and a casing. The flame tube forms an inner layer of the main temperature-bearing structure, which withstands the direct erosion of the mainstream high-temperature gas. The casing forms an outer layer of the main pressure-bearing structure, providing the necessary structural support and forming a closed annular cavity. The flame tube and the casing are both designed as a cylindrical structure surrounded by four walls on the top, bottom, left and right. Four independent closed cooling cavities are formed between the four walls of the casing and the flame tube and the inlet and outlet flange plates on the front and rear ends ( Figure 4 、 Figure 5(as shown), used to introduce cooling gas to achieve multi-faceted cooling of the flame tube. Optical glass windows are correspondingly provided on the four walls of the casing and flame tube, allowing for laser incidence and non-contact visual measurement of high-temperature flow fields, and providing a variety of optical measurement path options. The upper and lower walls 220 and 221 of the flame tube are each equipped with replaceable flow channel mounting blocks, each with a different wall structure. The upper and lower optical glass windows of the flame tube are correspondingly positioned on the flow channel mounting blocks, and the optical glass is provided with multiple mixing holes 20, forming a mixed glass. A head swirler mounting plate 211 is provided at the front end of the flame tube, located on the inlet flange plate 21, on which multiple swirlers 210 are mounted.

[0043] More specifically, Figure 2 The XY plane cross-sectional view of the main part of the test piece, i.e. the main mixing section. The cyclone mounting plate 211 at the entrance of the central chamber is equipped with three cyclones 210 ( Figure 3 As shown), the straight high-temperature incoming flow is forced to transform into a strong swirling turbulent flow before entering the flame tube, providing a turbulent mixing foundation for the downstream lateral jet, which helps to enhance the mixing uniformity and the ability to adjust the disturbance scale. The jet mixing gas first passes through three NPT connectors 237 ( Figure 5 As shown) into the mixing air box 22 provided above and below the casing, and the uniform flow plate 236 ( Figure 8 As shown in the figure, the swirler 210 is evenly distributed in the cavity between the upper wall of the flame tube and the upper wall of the casing under the action of the swirler 210, and then enters the flame tube through the mixing hole 20 to form a jet, which is mixed and merged with the mainstream. Preferably, the swirler 210 installed on the swirler mounting plate 211 is structurally designed to be detachable and replaceable. According to the test requirements, a swirler combination with different swirl numbers is selected to be installed, which is used to convert the upstream uniform and straight high-temperature incoming flow into strong swirling turbulence of different intensities before entering the flame tube, so as to realize the study of mixing characteristics under different swirl intensities, provide a reference for the design of the swirler of the combustion chamber, and optimize the combustion efficiency and emission performance of the combustion chamber.

[0044] In the main mixing section 2 of the present invention, the four upper, lower, left, and right walls 220, 221, 226, and 227 of the flame tube and the corresponding walls 222, 223, 224, and 225 of the casing are designed as modular flat panels with a straight structure for easy installation. The upper wall 220 and lower wall 221 of the flame tube are each equipped with a replaceable flow channel mounting bracket, which is connected to the flame tube body through a screw connection or plug-in connection, allowing for quick installation and removal.

[0045] Preferably, the replaceable flow channel mounting seat includes a flat flow channel mounting seat 217 and a contraction flow channel mounting seat 218, wherein the contraction flow channel mounting seat 218 has different contraction ratio options to achieve transverse jet mixing characteristics under different contraction ratio conditions. The flat flow channel mounting seat 217 includes at least two structural forms with and without cooling air film slit flow channels. The flat flow channel mounting seat 217 without cooling air film slit flow channels has an inner surface flush with the inner wall of the flame tube, forming a flow channel of equal cross-section, which is suitable for basic jet structure research; the flat flow channel mounting seat 217 with cooling air film slit flow channels includes a cooling air film slit flow channel 215 and a guide baffle 216. Different flow channel mounting modules are replaced according to experimental needs to construct a transverse jet mixing wall environment under different boundary conditions.

[0046] The main mixing section 2 of the present invention is a vertically symmetrical structure, which supports a variety of mounting seat module switching combinations. Figure 2 The lower wall surface 221 of the middle flame tube is shown as the contraction flow channel mounting seat 218, and the upper wall surface 220 of the flame tube is shown as the flat flow channel mounting seat 217 with the cooling air film slit flow channel. Figure 2 The middle contraction flow channel mounting seat 218 is replaced with the flat flow channel mounting seat 217 to meet the test requirements of the upper and lower counter-jet of the double flat flow channels; similarly, the upper and lower can also be replaced with the flat flow channel mounting seat 217 with a cooling air film structure (215, 216) to conduct the counter-jet test under the condition of bilateral cooling air film; similarly, Figure 2 The flat straight channel mounting block 217 on the upper wall of the center flame tube was replaced with a contraction channel mounting block 218 to conduct bilateral contraction counter-jet tests (contraction channel mounting blocks with different contraction ratios were replaced as needed). If a flat straight channel mounting block (without cooling air structures 215 and 216), a flat straight channel mounting block 217 with cooling air slit channels, or a contraction channel mounting block 218 were installed on only one of the upper and lower walls of the flame tube, and a blind plate was used to replace the mixed glass on the opposite side for sealing, and mixed glass 239 with different structures was then used for replacement and combination, a series of relatively basic single-sided jet tests could be conducted.

[0047] Figure 3 Will Figure 2 The upper and lower walls and head of the flame tube are shown in three dimensions to facilitate a better understanding of how to replace the different types of mounting brackets described in this paragraph. Figure 2 、 Figure 3 The flat flow channel mounting seat 217 with the cooling air film slit flow channel in the present invention is described in detail. Figure 2 、 Figure 3As shown, the cooling air film slit flow channel 215 extends in the left-right direction and is axially arranged in the transition area between the flame tube wall and the mixing hole 20, its inlet end is connected to the cavity between the upper and lower walls of the casing and the corresponding walls of the flame tube, and its outlet end is provided with a guide baffle 216 formed on the inner wall of the flame tube. The structure of the guide baffle 216 is arranged so that the outlet air flow direction is parallel to the mainstream direction in the flame tube, guiding the cooling air flow to form a cooling air film layer on the inner wall of the flame tube.

[0048] It should be added that the width of the cooling film slit flow channel 215 is adjustable, and a detachable and replaceable limit block is provided for adjusting the slit width. By replacing the limit blocks of different thicknesses to adjust the slit channel width, the effective flow cross-section of the channel is changed, and the cooling film flow rate and coverage are precisely controlled. It is suitable for constructing transverse jet mixing experiments under various local cooling boundary conditions, and can be used to study the development behavior of transverse jets under different cooling boundaries and the law of change in mixing efficiency, providing experimental data support for combustion chamber thermal protection design and film cooling optimization. The specific implementation method is as follows: there are two countersunk through holes on the downstream side of the flow direction of the slit flow channel 215, and there are two threaded holes at the corresponding positions of the limit block. The hexagon socket bolts are passed through the through holes from the downstream direction, and the limit blocks of different thicknesses are fixed in the slit flow channel 215. The cooling air flow rate is adjusted by changing the flow area.

[0049] The following combination Figure 2 、 Figure 3 The main combustion hole related structure of the present invention is introduced in detail. Figure 2 、 Figure 3 As shown, two rows of main combustion holes 213 are provided in front of the replaceable flow channel mounting seat of the upper wall 220 and the lower wall 221 of the flame tube, and each row of main combustion holes 213 is arranged in the left-right direction. The outer side of the air inlet end of the main combustion hole 213 is provided with a chamber partition 214 which is arranged on the outer wall of the flame tube and bent at the front end to abut against the inner wall of the swirler mounting plate 211. A main combustion hole chamber structure is formed between the chamber partition 214 and the outer wall of the flame tube and the inner wall of the swirler mounting plate 211; the swirler mounting plate 211 includes two structural forms with and without air supply slits. For the swirler mounting plate with air supply slits, its An air supply slit 212 extending in the left-right direction is respectively provided on the upper and lower sides. The inlet end of each air supply slit 212 is connected to the air inlet diffuser section, and the outlet end is connected to the main combustion hole chamber, which is used to introduce part of the mainstream high-temperature combustion gas into the main combustion hole chamber; when it is necessary to conduct transverse jet mixing research under the condition of cut-off swirl, a swirler mounting plate with air supply slits is selected to form controllable upper and lower counter-jet flows through the upper and lower main combustion holes to cut off the strong swirling mainstream; when the main combustion hole jet is not needed, the swirler mounting plate with air supply slits is replaced with a swirler mounting plate without air supply slits to close the main combustion hole airflow channel.

[0050] Figure 4 、 Figure 5 The main mixing section 2 demonstrates its all-around double-layer structure and annular cavity ventilation cooling capabilities. Four cooling cavities are formed between the casing and the walls of the flame tube, as well as the inlet and outlet flanges at the front and rear ends. The four cooling chambers between the flame tube and casing walls are independent, each with an airflow outlet 228 at the rear, which is connected to the exhaust structure. The upper and lower chambers communicate with the mixing gas supply system, providing the mixing gas required for the cross-jet flow. Their rear airflow outlets 228 are blocked, allowing air to enter the flame tube through the mixing holes 20 and mix with the main flow. The left and right chambers have their rear airflow outlets 228 open, allowing cold external air to enter the chambers through the interface 25. Through heat exchange, they cool the left and right sidewalls 226 and 227 of the flame tube, ensuring the stability of the window and structure.

[0051] This structural design allows the upper and lower chambers to perform both mixing and structural insulation functions, while the left and right chambers provide dedicated sidewall thermal protection. The four chambers are also independent of each other, preventing interference between the cooling fluids and ensuring uniform and controllable cooling. The cooling gas flow rate and temperature are adjustable and can be dynamically set based on the required mainstream temperature and heat flux boundary. This allows for the study of transverse jet development under different thermal boundary conditions, further resembling actual combustion chamber operation and improving data applicability and reliability.

[0052] Figure 6 The multi-layer pressure-resistant glass window structure and the uniform flow plate of the mixing gas collecting box are displayed. Figure 7 、 Figure 8 They are detailed cross-sectional views of the two. Figure 7As shown, the four walls 222, 223, 224, and 225 of the housing are each equipped with a multi-layer, pressure-resistant optical window structure to ensure optical safety and sealing reliability during high-temperature and high-pressure laser diagnostic experiments such as PIV and PLIF. The core component of each set of optical windows is quartz glass 232, which has excellent visible and ultraviolet light transmittance and high-temperature stability. Quartz glass 232 is placed between the upper and lower stainless steel frames 231 and 233. The depth of the stainless steel frames is 2-3 mm greater than the thickness of the glass. This allows for the application of high-temperature resistant adhesive between the two for sealing and cushioning. This provides both a preload gap and acts as an elastic buffer to reduce stress concentration during thermal cycling. This structure can accommodate differential linear expansion caused by sudden temperature changes, preventing glass breakage. Outside the upper and lower stainless steel frames are two layers of graphite gaskets 230 and 234. Graphite's softness and excellent high-temperature compressibility also act as a buffer, effectively improving stress distribution and absorbing dynamic shock loads. A cover plate 235 presses the glass against the mounting base 229, and bolts are tightened using a torque wrench to ensure uniform stress distribution around the glass edges and avoid localized load concentration. This structure, designed with full consideration of the strength margins required for thermal-mechanical coupling, can withstand high-temperature flow field erosion and thermal shock loads exceeding 0.5 MPa for long periods, ensuring the integrity, sealing, and optical transparency of the optical window during testing.

[0053] Figure 8 The relevant structures of the mixing air collecting box 22 and the flow plate 236 are further shown. In the specific implementation, the upper and lower walls 222 and 223 of the casing are respectively provided with a mixing air intake groove extending in the left and right directions (such as Figure 1 、 2 As shown), the air inlet groove is arranged in the axial direction in the front area of ​​the glass and cover plate 23 on the upper wall of the casing. A mixing air box 22 is fixedly installed on the outside of the air inlet groove, which serves as an intermediate buffer and rectification structure for the mixed gas. The mixed air enters the air box 22 through three NPT connectors 237, and then enters the chamber between the upper wall 222 of the casing and the upper wall 220 of the flame tube from the air box 22. The flow is uneven due to the serious expansion of the space, so a flow equalizer 236 is set up to solve this problem. The design idea is to set a porous structure flow equalizer 236 near the bottom of the mixing air box 22. The flow equalizer 236 reduces the flow area in the area facing the NPT connector to weaken the local impact momentum, and increases the flow area in other areas to compensate for the difference in flow kinetic energy, thereby achieving a balance between the overall air flow velocity and flow rate. CFD simulation verification shows that after adding the flow equalizer 236, the recirculation area near the mixing hole 20 is significantly reduced and the air flow rate is similar, which can ensure that the amount of gas entering multiple mixing holes is similar. After the mixed air enters the mixing air collecting box 22 through the NPT connector 237, it is evenly distributed to the chamber between the upper and lower walls of the casing and the corresponding walls of the flame tube under the action of the flow equalizer 236, and then enters the flame tube through the mixing hole 20 to form a horizontal jet.

[0054] Figure 9 This is a schematic diagram of the structure of the hybrid glass window. Figure 10 The following is a detailed cross-sectional diagram. Figure 9 and Figure 10 As shown, the upper and lower walls of the flame tube can be installed with mixed glass 239 of different structural forms, which are processed with various types of mixed holes with different aperture sizes, orifice shapes (such as circular, elliptical, slit-shaped, etc.) and different hole arrangements (such as uniform array, gradient distribution, local dense distribution, etc.) to construct multi-parameter controllable transverse jet boundary conditions. The mixed glass 239 is assembled in a detachable and replaceable manner in the glass mounting groove of the flow channel mounting seat 217 or 218. During installation, a layer of flexible graphite gasket 238 and 240 is laid on the upper and lower sides of the mixed glass respectively to play a role in thermal stress buffering and mechanical shock absorption, and is tightened and fixed as a whole by a structural cover plate 241. The bolt tightening process uses a constant torque tool to ensure uniform stress distribution and no local stress concentration damage occurs at the edge of the glass.

[0055] Because this test apparatus is designed with an "inner layer primarily bearing temperature and an outer layer primarily bearing pressure," the prevailing pressure within the flame tube during testing is nearly identical to the jet gas pressure in the chamber between the casing and the flame tube. Therefore, the intermixed glass 239 can be designed to be thinner, with graphite gaskets 238 and 240 placed directly above and below the glass to act as a buffer. The glass is then pressed against the mounting base 217 with a cover plate 241. The above depicts the intermixed glass structure of the flat flow channel mounting base 217; the intermixed glass structure of the contraction flow channel mounting base 218 is similar.

[0056] Furthermore, the exhaust structure section 3 in the embodiment of the present invention is as follows Figure 1 As shown, it is used to guide the orderly discharge of high-temperature exhaust gas generated during the experiment and control the exhaust gas temperature. Its front end is connected to the outlet of the main mixing section 2 through the exhaust section inlet flange 31, forming a downstream continuation path for the mainstream gas flow. The structure includes an exhaust gas collecting box with a front end connected to the flame tube outlet. The upper and lower or left and right side walls of the exhaust gas collecting box are provided with exhaust channels connected to its inner cavity. The exhaust channels are equipped with high-temperature exhaust cooling structures. The rear wall of the exhaust gas collecting box is provided with a rear optical glass window 32 near the mixing section outlet to shorten the laser incident path and reduce laser attenuation during the jet measurement process. The exhaust channel is designed as two upper and lower U-shaped bend pipe structures to leave space for optical path arrangement. The high-temperature exhaust cooling structure installed on the exhaust channel includes cooling water jackets 34 and 35 installed on the outer wall of the exhaust channel and a spray water system 36 sprayed into the exhaust channel. The cooling water flows from bottom to top in the water jacket interlayer to achieve heat transfer and cooling. The spray water directly sprays water mist into the exhaust mainstream to reduce the temperature of the high-temperature exhaust gas, ensuring that the exhaust temperature is lower than the maximum withstand temperature of the rear-end valve, thereby protecting the rear-end equipment of the test device.

[0057] In summary, the present invention solves the problems of the existing technology such as poor structural adaptability, weak window pressure resistance, poor mixture uniformity and severe laser measurement attenuation by constructing a modular replaceable structure, a double-layer composite cooling system, a mixed gas uniform flow optimization device and a multi-directional optical observation channel. It significantly improves the authenticity, adjustability and repeatability of the transverse jet mixing characteristics test, and provides solid experimental support for the optimization design of aircraft engine combustion organization.

[0058] The above embodiments fully and effectively achieve the objectives of the present invention. Those skilled in the art will appreciate that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the above specific embodiments. Although the present invention has been described with reference to the embodiments currently considered to be the most practical and preferred, it should be understood that the present invention is not limited to the disclosed embodiments, and any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

Claims

1. An optical visualization test device suitable for studying the mixing characteristics of transverse jets under different conditions, characterized in that: At least: The air inlet diffuser section is designed as an expansion structure. Its inlet is connected to the external air supply system, and its outlet is connected to the downstream main mixing section. Its wall is designed as a high-temperature resistant structure. The main mixing section is arranged downstream of the air intake and expansion section, and includes a frame-type main structure and an inlet flange plate and an outlet flange plate arranged at the front and rear ends thereof, wherein: the frame-type main structure includes a coaxially arranged flame tube and a casing, the flame tube forms an inner main temperature-bearing structure, and the casing forms an outer main pressure-bearing structure; the flame tube and the casing are structurally designed to be a cylindrical structure surrounded by four upper, lower, left and right walls, and four independently closed cooling cavities are formed between the four walls of the casing and the flame tube and the inlet and outlet flange plates at the front and rear ends; and optical glass windows are correspondingly provided on the four walls of the casing and the flame tube; the upper and lower walls of the flame tube are provided with replaceable flow channel mounting seats, and different flow channel mounting seats have different wall structures, and the upper and lower optical glass windows of the flame tube are correspondingly arranged on the flow channel mounting seats, and the optical glass is provided with multiple mixing holes and formed into mixing glass; the front end of the flame tube is provided with a head swirler mounting plate located on the inlet flange plate, on which multiple swirlers are installed, which are used to convert the upstream uniform high-temperature incoming flow into a strong swirling turbulent flow before entering the flame tube; The exhaust structure section includes an exhaust gas collecting box connected to the flame tube outlet, and exhaust channels connected to its inner cavity are provided on the upper and lower or left and right side walls of the exhaust gas collecting box. A high-temperature exhaust cooling structure is provided on the exhaust channel, and a rear optical window close to the outlet of the mixing section is provided on the rear wall of the exhaust gas collecting box.

2. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 1 is characterized in that: In the air intake diffuser section, its wall is designed as a multi-layer high-temperature resistant structure, which at least includes a main thermal bearing layer of a metal pipe located on the inner side, a high-temperature glass fiber insulation layer wrapped on the outside, and a metal shell pressure-bearing layer located on the outermost side and bearing the structural pressure. The multi-layer structure is continuously arranged along the flow direction, and a sealed and thermally insulating interface is formed between each layer; a diffuser section outlet flange is provided at the outlet of the air intake diffuser section, and is connected to the inlet flange plate of the mixing structure section by fasteners, and a high-temperature resistant sealing gasket is provided at the connection interface between the two.

3. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 1 or 2, characterized in that: The overall design of the air intake diffuser section is a detachable and replaceable structure, including multiple replaceable diffuser flow channel modules. Different diffuser flow channel modules have different diffusion angles and length ratios. The diffusion angle range is designed to cover typical axial pre-swirl and non-swirl combustion chamber inlet conditions, and the inner wall surface of each module is smoothed and provided with a streamlined guide structure.

4. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 1 is characterized in that: The multiple swirlers installed on the head swirler mounting plate are arranged in the left-right direction, and each swirler is designed to be detachable and replaceable. A swirler combination with different swirl numbers is selected and installed according to test requirements to convert the upstream uniform and straight high-temperature flow into strong swirling turbulence of different intensities before entering the flame tube.

5. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 1 or 4, characterized in that: In the main mixing section, two rows of main combustion holes are provided in front of the replaceable flow channel mounting seat on the upper wall and the lower wall of the flame tube, and each row of main combustion holes is arranged in the left and right directions. A chamber partition is provided on the outer side of the air inlet end of the main combustion hole, which is arranged on the outer wall of the flame tube and bent at the front end to abut against the inner wall of the swirler mounting plate. A main combustion hole chamber structure is formed between the chamber partition and the outer wall of the flame tube and the inner wall of the swirler mounting plate; the swirler mounting plate includes two structural forms with and without air supply slits. For the swirler mounting plate with air supply slits, the upper and lower sides are respectively provided with There is an air supply slit extending in the left-right direction. The inlet end of each air supply slit is connected to the air inlet diffuser section, and the outlet end is connected to the main combustion hole chamber, which is used to introduce part of the mainstream high-temperature combustion gas into the main combustion hole chamber; when it is necessary to conduct transverse jet mixing research under the condition of cut-off swirl, a swirler mounting plate with air supply slits is selected to form controllable upper and lower counter-jet flows through the upper and lower main combustion holes to cut off the strong swirling mainstream; when the main combustion hole jet is not needed, the swirler mounting plate with air supply slits is replaced with a swirler mounting plate without air supply slits to close the main combustion hole airflow channel.

6. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 1, characterized in that: In the upper and lower optical glass windows of the flame tube, the mixed glass is installed in the glass mounting groove of the flow channel mounting seat in a detachable and replaceable manner. The mixing holes on different mixed glasses have different apertures, different shapes and / or different arrangements. When the mixed glass is installed, graphite gaskets that serve as buffers are laid on the upper and lower sides of the mixed glass, and are pressed into the glass mounting groove by a cover plate. Mixed glasses with different mixing hole structures can be selected and replaced according to test requirements.

7. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 1 or 6, characterized in that: In the main mixing section, the upper and lower walls of the casing are provided with a mixing air intake groove extending in the left and right directions, and the mixing air intake groove is axially arranged in front of the optical glass window of the casing, and the outer side of the mixing air intake groove is provided with a mixing air collecting box extending in the left and right directions and fixedly arranged on the wall of the casing. A number of pipe joints connected to the external air source are evenly distributed on the top plate of the mixing air collecting box in the left and right directions. A porous structure flow equalizer is provided at the bottom of the mixing air collecting box, and the area of ​​the flow equalizer facing each pipe joint is smaller than the flow area of ​​other areas so as to evenly distribute the mixed gas and reduce the backflow area near the mixing hole. After the mixed air enters the mixing air collecting box through the pipe joint, it is evenly distributed in the cavity between the upper and lower walls of the casing and the corresponding wall of the flame tube under the action of the flow equalizer, and then enters the flame tube through the mixing hole to form a horizontal jet.

8. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 7, characterized in that: In the main mixing section, the four upper, lower, left and right walls of the flame tube and the casing are all straight walls, and the replaceable flow channel mounting seats arranged on the upper and lower walls of the flame tube are installed by screw connection or plug-in. The replaceable flow channel mounting seats include flat flow channel mounting seats and contraction flow channel mounting seats, wherein different contraction flow channel mounting seats have different contraction ratio options, and the flat flow channel mounting seats include at least two structural forms with and without cooling air film slit flow channels, and different flow channel mounting modules are replaced according to test needs.

9. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 8, characterized in that: For the flat channel mounting base with a cooling air film slit flow channel, the cooling air film slit flow channel extends in the left and right directions and is axially arranged in the transition area between the flame tube wall and the mixing hole, its inlet end is connected to the cavity between the upper and lower walls of the casing and the corresponding walls of the flame tube, and its outlet end is provided with a guide baffle formed on the inner wall of the flame tube. The structure of the guide baffle is arranged to make the outlet air flow direction parallel to the mainstream direction in the flame tube, guiding the cooling air flow to form a cooling air film layer on the inner wall of the flame tube; and, a detachable and replaceable limit block for adjusting the slit width is provided in the cooling air film slit flow channel. The slit channel width is adjusted by replacing the limit blocks of different thicknesses, thereby changing the effective flow cross-section of the channel, thereby achieving fine control of the cooling air film flow and coverage range.

10. The optical visualization test device for studying the mixing characteristics of transverse jets under different conditions according to claim 1, characterized in that: Four independently closed cooling cavities are formed between the walls of the casing and the flame tube and the inlet and outlet flange plates at the front and rear ends. The upper and lower cooling cavities are connected to the mixed gas supply system to provide the mixed gas required for the lateral jet. The left and right cooling cavities are connected to the external cold air heat exchange system through the cooling gas interface, and an air flow outlet hole is opened on the rear side of the chamber and is connected to the exhaust structure section to cool the side wall of the flame tube through flow heat exchange.

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