Diesel engine combustion visualization test system and test method

Abstract

The present application provides a diesel engine combustion visualization test system and test method, the test system includes a visualization cylinder head and a light path processing unit; the visualization cylinder head is a multi-valve cylinder head, the visualization cylinder head has at least two intake valve installation positions and at least two exhaust valve installation positions; the visualization cylinder head includes an intake valve mechanism, an exhaust valve mechanism, a visualization window and a sealing sleeve; the intake valve mechanism is installed in the intake valve installation position, and the exhaust valve mechanism is installed in the exhaust valve installation position; wherein one of the exhaust valve installation positions is provided with a visualization window; the sealing sleeve is sealingly sleeved on the upper portion of the visualization window and forms a closed light path channel above the visualization window; the light path processing unit is used to receive in-cylinder combustion optical signals transmitted out of the closed light path channel through the visualization window.

Description

Technical Field

[0001] This invention relates to the field of high power density diesel engine development technology, specifically to a diesel engine combustion visualization testing system and testing method. Background Technology

[0002] The combustion process of an internal combustion engine directly determines its power, economy, emissions, and reliability. Visual observation of in-cylinder combustion is a core experimental method for studying combustion mechanisms and optimizing engine structure. Traditional in-cylinder visualization tests of internal combustion engines often employ optical engines, typically using quartz or other optical windows on the piston, cylinder liner, or cylinder head, combined with high-speed photography and optical path systems to acquire and analyze images of in-cylinder spray, mixing, and combustion processes. While this approach provides an effective means of combustion research under normal operating conditions, it is limited by the strength of optical materials and the methods of structural modification, limiting its use to lower pressures and loads. It is difficult to match the high-temperature, high-pressure, and supercritical operating environments of high-power-density diesel engines.

[0003] Most existing visualization testing systems require significant modifications to the engine itself, such as using transparent cylinder liners and lengthened pistons. These modifications significantly alter the in-cylinder flow field, squeezing intensity, and combustion chamber geometry, leading to noticeable discrepancies between test results and actual engine combustion conditions. Furthermore, conventional cylinder head arrangements struggle to balance high-pressure sealing, optical path stability, and oil contamination protection within a limited space. External active illumination can also interfere with the flame's self-illuminating signal, failing to accurately reflect the distribution of combustion free radicals and the flame development process under high-load conditions.

[0004] Based on this, the inventors of this application propose a diesel engine combustion visualization testing system and testing method to solve one or more of the above-mentioned technical problems. Summary of the Invention

[0005] The present invention solves the above-mentioned technical problems through the following technical solution: The first aspect of this invention provides a diesel engine combustion visualization test system, comprising: a visualization cylinder head and an optical path processing unit; The visualized cylinder head is a multi-valve cylinder head, and the visualized cylinder head has at least two intake valve mounting positions and at least two exhaust valve mounting positions; The visualized cylinder head includes an intake valve mechanism, an exhaust valve mechanism, a visualization window, and a sealing sleeve; The intake valve mechanism is installed at the intake valve mounting position, and the exhaust valve mechanism is installed at the exhaust valve mounting position; wherein, one of the exhaust valve mounting positions is equipped with a visualization window; The sealing sleeve is fitted onto the upper part of the visualization window and forms a closed optical path channel above the visualization window; The optical path processing unit is used to receive the in-cylinder combustion optical signals transmitted through the visualization window and the closed optical path channel.

[0006] By employing a multi-valve structure in the visualized cylinder head, the visualization window is directly positioned at one of the exhaust valve mounting locations, eliminating the need to modify the diesel engine piston, cylinder liner, and combustion chamber body. This preserves the in-cylinder flow and combustion environment of the actual engine to the greatest extent possible. Simultaneously, a sealed sleeve forms a closed optical path channel above the visualization window, ensuring reliable sealing of the high-temperature, high-pressure combustion gas and cooling water, while also guaranteeing stable transmission of in-cylinder combustion optical signals. This effectively solves the problems of large modifications required for traditional optical engines, weak pressure resistance, susceptibility to optical path contamination, and distorted test results. The system is now adaptable to the high-temperature, high-pressure conditions of high-power-density diesel engines, significantly improving the realism and reliability of in-cylinder combustion visualization observation.

[0007] According to one embodiment of the present invention, the visualization window is a sapphire window, the sapphire window is fixedly installed in a visualization window mounting bracket, and the visualization window mounting bracket is fixed to the cylinder head fire surface; The bottom end of the sealing sleeve is fixedly connected to the visual window mounting base.

[0008] According to one embodiment of the present invention, a protective cover is provided on the top of the sealing sleeve; The optical path processing unit includes a reflector, which is located within the closed optical path channel and disposed inside the protective cover.

[0009] According to one embodiment of the present invention, the angle of the reflector relative to the axis of the closed optical path channel is adjustable.

[0010] According to one embodiment of the present invention, the optical path processing unit further includes an optical filtering component and a high-speed camera; The optical filtering assembly includes a filter and an image intensifier, and the filter, the image intensifier, and the high-speed camera are arranged sequentially along the optical transmission path.

[0011] According to one embodiment of the present invention, the filter is a narrowband filter with a center wavelength of 308nm, 430nm or 510-560nm, used to selectively transmit OH, CH and C2 free radical self-luminous signals.

[0012] According to one embodiment of the present invention, it further includes a diesel engine body and an electric dynamometer, wherein the visualized cylinder head is mounted on the diesel engine body; The electric dynamometer is connected to the crankshaft of the diesel engine body via a coupling, and the electric dynamometer is used to reverse the diesel engine body to the target speed.

[0013] According to one embodiment of the present invention, it further includes a high-pressure fuel source, an electronic fuel injector, and an ECU controller, wherein the high-pressure fuel source is connected to the electronic fuel injector, and the ECU controller is communicatively connected to both the electronic fuel injector and the high-speed camera. The electronically controlled fuel injector is mounted on the visible cylinder head.

[0014] According to one embodiment of the present invention, it further includes a cylinder pressure sensor and a combustion analyzer; The cylinder pressure sensor is installed inside the cylinder of the diesel engine body. The cylinder pressure sensor is connected to the combustion analyzer for signal acquisition. The cylinder pressure sensor is used to acquire the cylinder pressure signal. The combustion analyzer is used to analyze the combustion thermodynamic information based on the received cylinder pressure signal.

[0015] According to one embodiment of the present invention, a processing terminal is further included, which is communicatively connected to the high-speed camera, the combustion analyzer, and the ECU controller. Attached Figure Description

[0016] The above and other features, properties and advantages of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings and embodiments, wherein: Figure 1 This is a schematic diagram of the diesel engine combustion visualization test system of the present invention; Figure 2 This is a schematic diagram of the structure of the cylinder head of the present invention. Figure 3 for Figure 2 The aforementioned cross-sectional view of the cylinder head at one angle; Figure 4 This is a flowchart of the diesel engine combustion visualization test method of the present invention.

[0017] 1. Visual cylinder head; 11. Intake valve mounting position; 12. Exhaust valve mounting position; 13. Intake valve mechanism; 14. Exhaust valve mechanism; 15. Visualization window; 16. Sealing sleeve; 17. Visualization window mounting bracket; 18. Protective cover; 2. Optical path processing unit; 21. Closed optical path channel; 22. Mirror; 23. Optical filtering assembly; 231. Filter; 232. Image intensifier; 24. High-speed camera; 3. Diesel engine block; 31. Cylinder head firing face; 32. Electric dynamometer; 33. Coupling; 34. High-pressure fuel source; 35. Electronic fuel injector; 36. ECU controller; 37. Cylinder pressure sensor; 38. Combustion analyzer; 4. Processing terminal. Detailed Implementation

[0018] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0020] Existing diesel engine visualization testing devices suffer from problems such as insufficient pressure resistance, excessive modification of the engine body, significant deviation between the in-cylinder combustion state and the real engine, and poor light path sealing and anti-pollution capabilities.

[0021] Based on this, please refer to Figure 1 and Figure 2 This application proposes a diesel engine combustion visualization test system, including a diesel engine body 3, a visualization cylinder head 1 and an optical path processing unit 2, wherein the visualization cylinder head 1 is installed on top of the diesel engine body 3.

[0022] Optionally, the visualization cylinder head 1 is a multi-valve cylinder head, having at least two intake valve mounting positions 11 and at least two exhaust valve mounting positions 12. The visualization cylinder head 1 includes an intake valve mechanism 13, an exhaust valve mechanism 14, a visualization window 15, and a sealing sleeve 16. The intake valve mechanism 13 is mounted on the intake valve mounting position 11, and the exhaust valve mechanism 14 is mounted on the exhaust valve mounting position 12. In this application, one of the exhaust valve mounting positions 12 is removed, and the visualization window 15 is installed. The sealing sleeve 16 is fitted over the upper part of the visualization window 15, forming a closed optical path channel 21 above the visualization window 15. The optical path processing unit 2 is used to receive the in-cylinder combustion optical signals transmitted through the visualization window 15 and the closed optical path channel 21.

[0023] like Figure 1 and Figure 2 As shown, the visualized cylinder head 1 is illustrated using two intake valve mounting positions 11 and two exhaust valve mounting positions 12 as examples. One of the two exhaust valve mounting positions 12 is equipped with an exhaust valve mechanism 14, while the other exhaust valve mechanism 14 is omitted, and instead a visualized window 15 and a sealing sleeve 16 are provided. Figure 2 (Point A).

[0024] Therefore, this application allows for the placement of a visualization window 15 in one of the exhaust valve mounting positions 12 while retaining the original normal intake and exhaust functions. This does not affect the normal scavenging process of the diesel engine, nor does it require modification of core components such as the piston, cylinder liner, and combustion chamber, thus maximizing the maintenance of the in-cylinder flow and combustion characteristics of the actual engine. Moreover, the multi-valve cylinder head layout provides ample space, facilitating the integration of the sealing sleeve 16 and the optical path processing unit 2 in the cylinder head area. This enables a compatible arrangement of high-pressure sealing and optical path transmission, allowing the testing system to meet the normal operation requirements of high-power-density diesel engines while also enabling reliable visualization and observation of the in-cylinder combustion process.

[0025] Meanwhile, this application utilizes the sealing sleeve 16 to form a closed optical path channel 21 on the upper part of the visualization window 15, which not only achieves reliable sealing of high-temperature and high-pressure gas and cooling water, but also ensures stable transmission of in-cylinder combustion optical signals. This effectively solves the problems of large modification requirements, weak pressure resistance, easy contamination of optical paths, and distortion of test results in traditional optical engines. It enables the test system to adapt to the high-temperature and high-pressure working conditions of high-power-density diesel engines, significantly improving the authenticity and reliability of in-cylinder combustion visualization observation.

[0026] Please continue to refer to Figure 1 and Figure 3 Optionally, the visualization window 15 is a sapphire window, which is fixedly installed in the visualization window mounting bracket 17, which is fixed to the cylinder head fire surface 31; the bottom end of the sealing sleeve 16 is fixedly connected to the visualization window mounting bracket 17.

[0027] This application uses a sapphire-based visualization window 15, which significantly improves the high temperature resistance, high pressure resistance, and impact resistance of the visualization window 15, thus making it suitable for the harsh working conditions of high power density diesel engine cylinders with high temperature and high pressure.

[0028] Moreover, by sealing the sapphire window to the cylinder head fire surface 31 through the visualization window mounting bracket 17, the installation strength and sealing reliability of the visualization window 15 can be guaranteed, while maintaining the original structure of the combustion chamber and the real combustion environment to the greatest extent.

[0029] In one implementation, such as Figure 2 and Figure 3 As shown, the sapphire window is disc-shaped with a diameter of 90mm and a thickness of 50mm. This design allows the sapphire window to meet the requirements for high temperature resistance, high pressure resistance, and impact resistance. In some other embodiments, the shape and size of the sapphire window can be chosen from other suitable shapes and sizes, which can be adjusted according to actual needs and are not limited here.

[0030] Please continue to refer to Figure 3The bottom end of the sealing sleeve 16 is fixedly connected to the visualization window mounting base 17. The connection between the sealing sleeve 16 and the visualization window mounting base 17 can be achieved by welding, integral machining, or bonding. By fixing the sealing sleeve 16 to the visualization window mounting base 17, a stable and closed optical path channel can be formed above the visualization window 15, thereby effectively isolating the in-cylinder combustion gas, cooling water, and lubricating oil contamination, ensuring clear and stable transmission of the in-cylinder combustion optical signal, and significantly improving the service life and observation accuracy of the testing system.

[0031] like Figure 1 and Figure 3 As shown, the top of the sealing sleeve 16 is provided with a protective cover 18; the optical path processing unit 2 includes a reflector 22, which is located inside the closed optical path channel 21 and inside the protective cover 18.

[0032] This application, by setting a protective cover 18 on the top of the sealing sleeve 16 and arranging the reflector 22 inside the closed optical path channel 21 and on the inside of the protective cover 18, can effectively block the contamination of the reflector 22 by the lubricating oil, oil vapor, and impurities splashed from the cylinder head mechanism. At the same time, the closed optical path channel 21 can form a stable and clean optical path transmission environment, avoiding the influence of external interference and stray light, ensuring that the reflector 22 can stably and accurately reflect the in-cylinder combustion optical signal to the subsequent imaging unit, significantly improving the clarity of combustion image acquisition and the long-term reliability of the test system.

[0033] Optionally, the angle of the axis of the reflector 22 relative to the closed optical path channel 21 is adjustable.

[0034] For example, a connecting rod (not shown) can be installed inside the protective cover 18, with a sphere at the end of the connecting rod. A spherical groove that rotates with the sphere is provided on one side of the reflector 22, allowing the operator to rotate the reflector 22 relative to the connecting rod to a suitable position. Alternatively, one side of the reflector 22 can be rotatably connected to the connecting rod via a pivot. The specific rotating connection structure between the reflector 22 and the protective cover 18 can be adjusted according to the actual rotation angle requirements and is not limited here.

[0035] This application sets the reflector 22 to be adjustable along the axis of the relatively closed optical path channel 21, which can flexibly adjust the reflection direction and imaging angle of the in-cylinder combustion optical signal. This allows it to adapt to the debugging needs of different shooting distances and different installation positions of the high-speed camera 24. The best observation angle can be obtained quickly without disassembling the entire optical path assembly, which effectively improves the versatility, debugging convenience and imaging flexibility of the test system.

[0036] Please continue to refer to Figure 1The optical path processing unit 2 also includes an optical filter assembly 23 and a high-speed camera 24; the optical filter assembly 23 includes a filter 231 and an image intensifier 232, and the filter 231, the image intensifier 232 and the high-speed camera 24 are arranged sequentially along the optical path transmission path.

[0037] The filter 231 is used to perform band filtering on the in-cylinder combustion optical signal, filtering out stray light and background radiation interference, and accurately extracting the target free radical emission signal. At the same time, the image intensifier 232 is used to amplify the weak fluorescence signal, which can improve the imaging signal-to-noise ratio and clarity. Finally, the high-speed camera 24 completes the high-quality combustion image acquisition, enabling the system to effectively capture and perform high-precision visual diagnosis of weak combustion emission signals in the diesel engine cylinder.

[0038] Optionally, the filter 231 is a narrowband filter 231 with a center wavelength of 308nm, 430nm or 510-560nm, used to selectively transmit OH, CH and C2 free radical self-luminous signals.

[0039] This application employs a narrowband filter 231 corresponding to a specific wavelength, which can selectively transmit the self-luminous signals of key combustion free radicals such as OH, CH, and C2, suppress background radiation in non-target bands, and, combined with a high-gain image intensifier 232, can improve the imaging clarity and diagnostic accuracy of flame intermediate products.

[0040] Please continue to refer to Figure 1 The testing system also includes an electric dynamometer 32, which is connected to the crankshaft of the diesel engine body 3 via a coupling 33. The electric dynamometer 32 is used to reverse the diesel engine body 3 to the target speed.

[0041] This application uses coupling 33 to reverse-drive the diesel engine body 3 to the target speed, which can stably establish the same in-cylinder compression pressure and temperature environment as the actual engine without relying on the engine's own continuous work. It can accurately control the test speed and crankshaft phase, and together with the visualized cylinder head 1, realize a single combustion cycle test. This can avoid damage to the optical components caused by continuous operation at high temperature and high pressure, and ensure that the in-cylinder flow and combustion process are close to the real working conditions, which greatly improves the safety of the test, the repeatability of data and the authenticity of the test results.

[0042] Furthermore, the testing system also includes a high-pressure fuel source 34, an electronic fuel injector 35, and an ECU controller 36. The high-pressure fuel source 34 is connected to the electronic fuel injector 35, and the ECU controller 36 is communicatively connected to the electronic fuel injector 35 and the high-speed camera 24, respectively. The electronic fuel injector 35 is installed on the visual cylinder head 1.

[0043] Specifically, the ECU controller 36 of this application can control the electronic fuel injector 35 to perform a single fuel injection combustion. Moreover, the ECU controller 36 can synchronously control the fuel injection and the high-speed camera 24 to ensure that the combustion process and image acquisition are strictly phase synchronized. This ensures that the acquired combustion image corresponds precisely to the actual fuel injection and combustion time, effectively improving the accuracy of the test data and the repeatability of the experiment.

[0044] In one embodiment, the test system further includes a cylinder pressure sensor 37 and a combustion analyzer 38; the cylinder pressure sensor 37 is installed inside the cylinder of the diesel engine body 3, and the cylinder pressure sensor 37 is connected to the combustion analyzer 38 for signal acquisition. The cylinder pressure sensor 37 is used to acquire the cylinder pressure signal, and the combustion analyzer 38 is used to analyze the combustion thermodynamic information based on the received cylinder pressure signal.

[0045] Furthermore, the testing system also includes a processing terminal 4, which is communicatively connected to the high-speed camera 24, the combustion analyzer 38, and the ECU controller 36.

[0046] It should be noted that this application, by employing reverse drag and single-injection combustion, measures the combustion process of only one working cycle, without involving continuous exhaust, thermal management, or continuous heat exchange. Therefore, eliminating one exhaust valve in this application will not change the in-cylinder compression pressure, temperature, spray wall impact, or flame development. Moreover, diesel engine combustion occurs near the top dead center of compression, at which point all exhaust valves are closed. Removing one exhaust valve only affects the exhaust stroke and will not affect the core test stages of compression, combustion, and expansion, thus not affecting the test results.

[0047] Based on this, the inventors of this application have opted not to install the exhaust valve mechanism 14 in one of the exhaust valve mounting positions 12, but instead to set up a visualization window 15, while keeping the other engine structures unchanged (such as pistons, cylinder liners, and connecting rods). As a result, this application can make the test environment as close as possible to the real conditions inside the cylinder, effectively solving the problem of large modifications required for traditional optical engines. This allows the test system to be adapted to the high temperature and high pressure conditions of high power density diesel engines, significantly improving the authenticity and reliability of in-cylinder combustion visualization observation.

[0048] Please refer to Figure 4 This application also proposes a diesel engine combustion visualization test method, which uses the diesel engine combustion visualization test system described above, and the test method includes: S1. Remove the exhaust valve mechanism at one of the exhaust valve mounting positions in the visualized cylinder head, and install a visualized window and sealing sleeve to form a closed light path channel; S2. The optical path processing unit receives the in-cylinder combustion optical signal transmitted through the visualization window and optical path channel.

[0049] The following describes the testing method flow of this application: Before testing, the diesel engine was preheated using its own lubricating oil and cooling water system to meet operating conditions. Furthermore, a separate high-pressure fuel source was used to increase the fuel injection pressure to the target value.

[0050] During the test, the electric dynamometer and the diesel engine were connected via a coupling. The electric dynamometer reversed the diesel engine to the target speed, and the speed signal was synchronously transmitted to the ECU controller and the combustion analyzer. During the reversing process, the diesel engine's air compressor provided air supply normally, and the intake and exhaust valves operated normally, making the intake, exhaust, and in-cylinder compression processes of the diesel engine close to those during normal operation. Simultaneously, during the reversing process, the cylinder pressure sensor measured the in-cylinder pressure, and the combustion analyzer read and analyzed the in-cylinder pressure and temperature.

[0051] Because the electronic fuel injectors and high-speed cameras are both controlled by the ECU controller, which is connected to the processing terminal, when the diesel engine is towed to the target speed and the cylinder pressure, temperature, and pressure reach the set targets, the processing terminal sends a fuel injection signal at a designated phase, and the ECU controller synchronously controls the fuel injectors and the high-speed camera.

[0052] After fuel is injected by the injector, it burns under the compression of the engine. The resulting optical signal passes through the visualization window, is reflected by a mirror, and is received by a high-speed camera, then transmitted to the processing terminal for storage. Simultaneously, the in-cylinder pressure signal generated by combustion is sent to the combustion analyzer via the cylinder pressure sensor. After analysis, the thermodynamic information of combustion is obtained and transmitted to the processing terminal for storage.

[0053] Subsequently, by integrating and processing the combustion optical image information obtained from the high-speed camera and the combustion thermodynamic information obtained from the combustion analyzer, the combustion state information of the internal combustion engine cylinder can be obtained.

[0054] In the description of the embodiments of this application, unless otherwise expressly specified and limited, the technical terms such as "installation", "connection", "joining", and "fixing" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can also refer to mechanical connections. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0055] This application uses specific terms to describe embodiments of the application. Terms such as "an embodiment," "one embodiment," and / or "some embodiments" refer to a particular feature, structure, or characteristic associated with at least one embodiment of the application. Therefore, it should be emphasized and noted that references to "an embodiment," "one embodiment," or "an alternative embodiment" in different locations throughout this specification do not necessarily refer to the same embodiment. Furthermore, certain features, structures, or characteristics in one or more embodiments of the application can be appropriately combined.

[0056] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A diesel engine combustion visualization testing system, characterized in that, include: Visualized cylinder head and optical path processing unit; The visualized cylinder head is a multi-valve cylinder head, and the visualized cylinder head has at least two intake valve mounting positions and at least two exhaust valve mounting positions; The visualized cylinder head includes an intake valve mechanism, an exhaust valve mechanism, a visualization window, and a sealing sleeve; The intake valve mechanism is installed at the intake valve mounting position, and the exhaust valve mechanism is installed at the exhaust valve mounting position; wherein, one of the exhaust valve mounting positions is equipped with a visualization window; The sealing sleeve is fitted onto the upper part of the visualization window and forms a closed optical path channel above the visualization window; The optical path processing unit is used to receive the in-cylinder combustion optical signals transmitted through the visualization window and the closed optical path channel.

2. The diesel engine combustion visualization test system according to claim 1, characterized in that, The visualization window is a sapphire window, which is fixedly installed in a visualization window mounting bracket, and the visualization window mounting bracket is fixed to the cylinder head fire surface; The bottom end of the sealing sleeve is fixedly connected to the visual window mounting base.

3. The diesel engine combustion visualization test system according to claim 1, characterized in that, The top of the sealing sleeve is equipped with a protective cover; The optical path processing unit includes a reflector, which is located within the closed optical path channel and disposed inside the protective cover.

4. The diesel engine combustion visualization test system according to claim 3, characterized in that, The angle of the reflector relative to the axis of the closed optical path channel is adjustable.

5. The diesel engine combustion visualization test system according to claim 3, characterized in that, The optical path processing unit also includes an optical filtering component and a high-speed camera; The optical filtering assembly includes a filter and an image intensifier, and the filter, the image intensifier, and the high-speed camera are arranged sequentially along the optical transmission path.

6. The diesel engine combustion visualization test system according to claim 5, characterized in that, The filter is a narrowband filter with a center wavelength of 308nm, 430nm, or 510-560nm, used to selectively transmit OH, CH, and C2 free radical self-luminous signals.

7. The diesel engine combustion visualization test system according to claim 5, characterized in that, It also includes a diesel engine body and an electric dynamometer, with the visible cylinder head mounted on the diesel engine body; The electric dynamometer is connected to the crankshaft of the diesel engine body via a coupling, and the electric dynamometer is used to reverse the diesel engine body to the target speed.

8. The diesel engine combustion visualization test system according to claim 7, characterized in that, It also includes a high-pressure fuel source, an electronic fuel injector, and an ECU controller. The high-pressure fuel source is connected to the electronic fuel injector, and the ECU controller is communicatively connected to both the electronic fuel injector and the high-speed camera. The electronically controlled fuel injector is mounted on the visible cylinder head.

9. The diesel engine combustion visualization test system according to claim 8, characterized in that, It also includes cylinder pressure sensors and combustion analyzers; The cylinder pressure sensor is installed inside the cylinder of the diesel engine body. The cylinder pressure sensor is connected to the combustion analyzer for signal acquisition. The cylinder pressure sensor is used to acquire the cylinder pressure signal. The combustion analyzer is used to analyze the combustion thermodynamic information based on the received cylinder pressure signal.

10. The diesel engine combustion visualization test system according to claim 9, characterized in that, It also includes a processing terminal, which is communicatively connected to the high-speed camera, the combustion analyzer, and the ECU controller.

11. A method for visualizing diesel engine combustion, characterized in that, The diesel engine combustion visualization test system as described in any one of claims 1-10, wherein the test method includes: Step 1: Remove the exhaust valve mechanism at one of the exhaust valve mounting positions on the visualized cylinder head, and install a visualized window and sealing sleeve to form a closed light path channel; Step 2: Receive the in-cylinder combustion optical signal transmitted through the visualization window and the optical path channel using the optical path processing unit.

Images