Large scale scramjet liquid fuel injection optimization design method

Abstract

The application provides a large-scale scramjet liquid fuel injection section optimization design method, which comprises the following steps: obtaining the particle size distribution at different positions downstream of a nozzle of a scaled scramjet when liquid fuel injection is performed by the nozzle under supersonic inflow conditions; determining an equal ratio magnification n of a scaled scramjet combustion chamber to a large-scale scramjet combustion chamber; and optimizing the nozzle diameter of the large-scale scramjet liquid fuel injection section so that the particle size distribution at a position downstream of the nozzle of the large-scale scramjet liquid fuel injection section and a distance k from the nozzle is the same as the particle size distribution at a position downstream of the nozzle of the scaled scramjet liquid fuel injection section and a distance kd from the nozzle, d is the nozzle diameter of the scaled scramjet liquid fuel injection section, and k is greater than 0. The application can ensure that the engine has the same atomization characteristics under different nozzle diameters.

Description

Technical Field

[0001] This invention belongs to the field of scramjet engine design technology, and specifically relates to an optimized design method for the liquid fuel injection section of a large-scale scramjet engine. Background Technology

[0002] A scramjet engine mainly consists of an air intake, an isolator, a combustion chamber, and a tail nozzle. Due to its excellent performance at high Mach numbers, it is considered the preferred propulsion system for hypersonic vehicles. As the core component of scramjet engine flow design, the combustion chamber has always been a key research focus in the field of hypersonic propulsion technology; its performance directly determines the overall design level of the scramjet engine.

[0003] Currently, my country has made significant progress in the research of small-scale engines (with smaller nozzle diameters). However, for the design of large-scale engines, how to apply the existing laws obtained under small nozzle diameters to the design of large-scale engines through similarity criteria remains an urgent problem to be solved. Clarifying the similarity of liquid fuel jet atomization characteristics at different flow directions is essential, as this can greatly reduce the design and development cycle and cost of large-scale engines.

[0004] Currently, due to challenges such as high experimental difficulty, long testing time, and high testing costs, the internal surface of large-scale scramjet engines is generally derived directly from scaled-down models. However, directly extending the conclusions and rules summarized from scaled-down and simplified engine combustion chambers to the design of large-scale engine combustion chambers presents the following problems:

[0005] (1) After the engine size is enlarged proportionally, the diameter of the liquid fuel nozzle cannot be directly increased proportionally. Some existing rules obtained under small nozzle diameter can be directly applied to the design of large-size engines.

[0006] (2) When the injection pressure drop remains constant, the jet penetration depth increases proportionally with the nozzle diameter, but the atomization characteristics of the liquid jet (such as particle size distribution) do not increase proportionally, which cannot provide the necessary reference for the design of the injection scheme. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention proposes an optimized design method for the liquid fuel injection section of a large-scale scramjet engine.

[0008] To achieve the above-mentioned technical objectives, the technical solution proposed by this invention is as follows:

[0009] On one hand, this invention provides an optimized design method for the liquid fuel injection section of a large-scale scramjet engine, comprising:

[0010] Numerical simulation of a scaled scramjet engine under supersonic inflow conditions was conducted to obtain the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine during liquid fuel injection. Let the distance between the different downstream positions of the nozzle and the nozzle be kd, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0.

[0011] Determine the scaling factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber;

[0012] The nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine is optimized to be [missing information]. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

[0013] Furthermore, the ignition positions of large-scale scramjet engines can be obtained based on the above scheme, specifically including:

[0014] Based on the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of a scaled-down scramjet engine, the downstream position of the nozzle containing the suitable particle size distribution for ignition is determined. Let k be the distance between the downstream position of the nozzle containing the suitable particle size distribution for ignition in the scaled-down scramjet engine and the nozzle. * d, k * Greater than 0;

[0015] The nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine is optimized to be [missing information]. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The location is downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance k from the nozzle. * The same particle size distribution at point d indicates that the downstream of the nozzle in the liquid fuel injection section of the large-scale scramjet engine, at a distance of [missing information], is [missing information]. The location is set as the ignition point for a large-scale scramjet engine.

[0016] Furthermore, the present invention provides a large-scale scramjet engine that uses any of the above-mentioned large-scale scramjet engine liquid fuel injection section optimization design methods to design its liquid fuel injection section.

[0017] Furthermore, the present invention provides an optimized design device for the liquid fuel injection section of a large-scale scramjet engine, comprising:

[0018] The first module is used to conduct numerical simulation of a scaled scramjet engine under supersonic inflow conditions. It obtains the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine when liquid fuel is injected. Let the distance between the different downstream positions of the nozzle and the nozzle be kd, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0.

[0019] The second module is used to determine the proportional magnification factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber.

[0020] The third module is used to optimize the nozzle diameter of the liquid fuel injection section of a large-scale scramjet engine. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

[0021] Furthermore, the first module includes determining the particle size distribution at different downstream positions of the nozzle during liquid fuel injection in the liquid fuel injection section of the scaled-down scramjet engine, based on the particle size distribution at which the suitable ignition particle size distribution is located downstream of the nozzle. Let k be the distance between the downstream position of the suitable ignition particle size distribution of the scaled-down scramjet engine and the nozzle. * d, k * Greater than 0;

[0022] The third module includes optimizing the nozzle diameter of the liquid fuel injection section of a large-scale scramjet engine. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The location is downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance k from the nozzle. * The same particle size distribution at point d indicates that the downstream of the nozzle in the liquid fuel injection section of the large-scale scramjet engine, at a distance of [missing information], is [missing information]. The location is set as the ignition point for a large-scale scramjet engine.

[0023] On the other hand, the present invention provides a computer system including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to perform the following steps:

[0024] Numerical simulation of a scaled scramjet engine under supersonic inflow conditions was conducted to obtain the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine during liquid fuel injection. Let the distance between the different downstream positions of the nozzle and the nozzle be kd, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0.

[0025] Determine the scaling factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber;

[0026] The nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine is optimized to be [missing information]. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

[0027] On the other hand, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein the processor executes the computer program to perform the following steps:

[0028] Numerical simulation of a scaled scramjet engine under supersonic inflow conditions was conducted to obtain the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine during liquid fuel injection. Let the distance between the different downstream positions of the nozzle and the nozzle be kd, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0.

[0029] Determine the scaling factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber;

[0030] The nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine is optimized to be [missing information]. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

[0031] The technical effects that this invention can achieve are:

[0032] (1) By conducting numerical simulation of a scaled scramjet engine under supersonic flow conditions, this invention can accurately obtain the particle size distribution at different downstream positions of the nozzle of the liquid fuel injection section of the scaled scramjet engine when liquid fuel is injected.

[0033] (2) This invention overcomes the limitations of proportionally enlarging the nozzle diameter in terms of penetration depth and span width. Under supersonic flow conditions, as the ramjet engine is enlarged from a small scale to a large scale, and the diameter of the liquid fuel nozzle in the combustion chamber increases, the method of this invention optimizes the nozzle diameter setting, ensuring that the engine has the same atomization characteristics under different nozzle diameters. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0035] Figure 1 A flowchart of an embodiment of the present invention;

[0036] Figure 2 This is a diagram showing the penetration depth of liquid jets with different nozzle diameters obtained in a simulation experiment.

[0037] Figure 3 This is a comparison of the dimensionless liquid jet penetration depth under different nozzle diameters obtained in a simulation experiment.

[0038] Figure 4 It was obtained from a simulation experiment. Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at different downstream positions under two amplification criteria: 1x and nx. (a) is based on... (a) Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 30d downstream of the nozzle and with nozzles of different diameters under the magnification criterion; (b) Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 30d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; (c) Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 30d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 45d downstream of the nozzle and with nozzles of different diameters under the magnification criterion; (d) is a comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 45d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; (e) is a comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 45d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; (f) is a comparison of the average particle size distribution along the longitudinal height of nozzles with different nozzle diameters on the symmetry plane of the jet center at a position 60d downstream of the nozzle and at a distance of 60d from the nozzle, based on the n-fold magnification criterion.

[0039] Figure 5 This is a schematic diagram of a structure according to an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the spirit of the disclosed content will be clearly explained below with reference to the accompanying drawings and detailed description. Any person skilled in the art, after understanding the embodiments of the present invention, can make changes and modifications based on the techniques taught in the present invention without departing from the spirit and scope of the present invention. The illustrative embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

[0041] Existing research has revealed the influence of nozzle diameter on the penetration depth of liquid jets. In experimental design, nozzle diameter is a key variable. The liquid-to-gas momentum flux ratio is calculated using formula (1.1), where Δp is the injection pressure drop and p0 is the total gas pressure. The ratio of liquid to gas momentum flux is transformed into an expression related to the pre-spray pressure; that is, the liquid-to-gas momentum flux ratio is adjusted by controlling the pre-spray pressure. Under the condition of maintaining a consistent liquid-to-gas momentum ratio, the influence of the nozzle diameter is studied.

[0042]

[0043] Figure 2 This paper presents simulation results showing the penetration depth of liquid jets under different nozzle diameters. Under a Mach number of 2.0, the penetration depths of water jets with different nozzle diameters (d = 0.5 mm, d = 0.7 mm, and d = 1.0 mm) are compared. Data points are all boundary points of the jet measured by a PDA. The dashed line represents the jet penetration depth curve obtained by fitting a power function, and the horizontal and vertical axes correspond to the actual distances from the nozzle center. Figure 2 It can be observed that as the nozzle diameter increases, the penetration depth of the jet increases significantly. Since the liquid-gas momentum flux ratio of the jet remains unchanged, the increase in penetration depth is entirely due to the increase in nozzle diameter.

[0044] Figure 3A simulation experiment is presented, showing a comparison of the dimensionless liquid jet penetration depths at different nozzle diameters (d = 0.5 mm, d = 0.7 mm, and d = 1.0 mm). Both the penetration depth and the distance from the nozzle orifice are dimensionless, using the nozzle diameter. Figure 3 The x and y axes in the graph are represented in logarithmic form. It can be seen that the dimensionless penetration depth curves are almost identical, and the penetration depth and nozzle diameter increase proportionally. The calculated maximum relative difference is 2.88%, which suggests that the penetration depth increases approximately proportionally with the proportional enlargement of the nozzle size.

[0045] like Figure 4 As shown in the simulation experiment, Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at different downstream positions for nozzles with different nozzle diameters (d = 0.5 mm, d = 0.7 mm, and d = 1.0 mm) under two scaling criteria of multiple and n, where (a) is based on (a) Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 30d downstream of the nozzle and with nozzles of different diameters under the magnification criterion; (b) Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 30d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; (c) Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 30d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; Comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 45d downstream of the nozzle and with nozzles of different diameters under the magnification criterion; (d) is a comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 45d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; (e) is a comparison of the average particle size distribution along the longitudinal height on the jet center symmetry plane at a position 45d downstream of the nozzle and with nozzles of different diameters under the n-fold magnification criterion; (f) Comparison of the average particle size distribution along the longitudinal height on the symmetry plane of the jet center at a position 60d downstream of the nozzle and with nozzles of different diameters under the multiplier amplification criterion. (f) Comparison of the average particle size distribution along the longitudinal height on the symmetry plane of the jet center at a position 60d downstream of the nozzle and with nozzles of different diameters under the n-fold amplification criterion. From the comparison at the three different positions, it can be seen that in the low-velocity region near the wall, the particle size distribution differs significantly under both amplification principles, while in the high-velocity region near the jet boundary, the particle size distribution matches well under both amplification principles. When selecting the flow direction, the particle size distribution measured with jets of different apertures is more consistent than that with the distribution at the same location, indicating that for jets of different apertures, the particle size distribution should be selected with the following parameters: When the flow direction characteristic length is used to dimensionlessly represent the flow direction distance of the jet, the particle distributions flowing through that cross-section at the same dimensionless location exhibit a certain degree of similarity. Therefore, it can be inferred that the atomization completion distance of the jet is approximately proportional to...

[0046] Based on the above analysis, referring to Figure 1 One embodiment provides an optimized design method for the liquid fuel injection section of a large-scale scramjet engine, comprising:

[0047] S1 conducts numerical simulation of a scaled scramjet engine under supersonic inflow conditions to obtain the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine when liquid fuel is injected.

[0048] Specifically, in S1, the distance between different downstream positions of the nozzle and the nozzle is set as kd, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0.

[0049] S2 determines the proportional magnification factor n from scaling up the scaled-down scramjet engine combustor to the large-scale scramjet engine combustor;

[0050] S3 optimizes the nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine.

[0051] Specifically, in S3, the nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine is optimized to be [missing information]. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

[0052] In one embodiment, a method for optimizing the liquid fuel injection section of a large-scale scramjet engine, as described above, is provided to obtain the ignition position of the large-scale scramjet engine. Specifically, this includes:

[0053] Based on the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of a scaled-down scramjet engine, the downstream position of the nozzle containing the suitable particle size distribution for ignition is determined. Let k be the distance between the downstream position of the nozzle containing the suitable particle size distribution for ignition in the scaled-down scramjet engine and the nozzle. * d, k * Greater than 0;

[0054] Determine the scaling factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber;

[0055] The nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine is optimized to be [missing information]. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The location is downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance k from the nozzle. * The same particle size distribution at point d indicates that the downstream of the nozzle in the liquid fuel injection section of the large-scale scramjet engine, at a distance of [missing information], is [missing information]. The location is set as the ignition point for a large-scale scramjet engine.

[0056] In one embodiment, k * =45. This invention has been verified through experimental calculations; the solution is feasible, and the results achieve the expected goals.

[0057] In one embodiment, a large-scale scramjet engine is provided, and its liquid fuel injection section is designed using the liquid fuel injection section optimization design method provided in any of the above embodiments.

[0058] In one embodiment, a large-scale scramjet engine is provided, and the ignition position of the large-scale scramjet engine is obtained based on the above-mentioned optimized design method for the liquid fuel injection section of the large-scale scramjet engine.

[0059] The optimization design method for the liquid fuel injection section of a large-scale scramjet engine is the same as in the above embodiments. Each step has been described in detail in the previous embodiments and will not be repeated here. Similarly, how to obtain the ignition position of the large-scale scramjet engine is the same as in the above embodiments. Each step has been described in detail in the previous embodiments and will not be repeated here.

[0060] In one embodiment, a device for optimizing the liquid fuel injection section of a large-scale scramjet engine is characterized by comprising:

[0061] The first module is used to conduct numerical simulation of a scaled scramjet engine under supersonic inflow conditions. It obtains the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine when liquid fuel is injected. Let the distance between the different downstream positions of the nozzle and the nozzle be kd, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0.

[0062] The second module is used to determine the proportional magnification factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber.

[0063] The third module is used to optimize the nozzle diameter of the liquid fuel injection section of a large-scale scramjet engine. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

[0064] The implementation methods of the above-mentioned modules can be the same as those in the previous embodiments, and will not be repeated here.

[0065] In this embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows. Figure 5 As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores the operating system, computer programs, and the database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores sample data. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements the steps of the optimized design method for the liquid fuel injection section of the large-scale scramjet engine described in the above embodiments.

[0066] Those skilled in the art will understand that Figure 5 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0067] In one embodiment, a computer device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the optimized design method for the liquid fuel injection section of a large-scale scramjet engine as described in the above embodiments.

[0068] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the optimized design method for the liquid fuel injection section of a large-scale scramjet engine as described in the above embodiments.

[0069] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0070] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0071] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for optimal design of liquid fuel injection section of a large scale scramjet engine, characterized in that, include: Numerical simulation of a scaled scramjet engine under supersonic inflow conditions was conducted to obtain the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine during liquid fuel injection. Let kd be the distance between the different downstream positions of the nozzle and the nozzle, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0. Determine the scaling factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber; The nozzle diameter of the liquid fuel injection section of the large-scale scramjet engine is optimized to be [missing information]. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

2. The method of claim 1, wherein, The particle size distribution at different positions downstream of the nozzle during liquid fuel injection based on the nozzle of the liquid fuel injection section of the scaled scramjet engine is determined, and a position downstream of the nozzle at which the particle size distribution suitable for ignition is located is determined. The distance between the position downstream of the nozzle at which the particle size distribution suitable for ignition is located and the nozzle of the scaled scramjet engine is k * d, k * greater than 0; Optimizing the nozzle diameter of the liquid fuel injection section of a large scale scramjet engine is such that the particle size distribution at a location downstream of the nozzle of the liquid fuel injection section of the large scale scramjet engine and at a distance k from the nozzle is the same as the particle size distribution at a location downstream of the nozzle of the liquid fuel injection section of a scaled scramjet engine and at a distance k * from the nozzle. The location downstream of the nozzle of the liquid fuel injection section of the large scale scramjet engine and at a distance k from the nozzle is set as the ignition location of the large scale scramjet engine.

3. The method of claim 2, wherein, k * ＝45。 4. A large scale scramjet engine characterized by, The liquid fuel injection section of the large-scale scramjet engine is designed using the optimization design method for the liquid fuel injection section as described in claim 1, 2, or 3.

5. A device for optimal design of liquid fuel injection section of a large scale scramjet engine, characterized in that, include: The first module is used to conduct numerical simulation of a scaled scramjet engine under supersonic inflow conditions. It obtains the particle size distribution at different downstream positions of the nozzle in the liquid fuel injection section of the scaled scramjet engine when liquid fuel is injected. Let the distance between the different downstream positions of the nozzle and the nozzle be kd, where d is the nozzle diameter of the liquid fuel injection section of the scaled scramjet engine, and k is greater than 0. The second module is used to determine the proportional magnification factor n from scaling up the scramjet engine combustion chamber to scaling up the large-scale scramjet engine combustion chamber. The third module is used to optimize the nozzle diameter of the liquid fuel injection section of a large-scale scramjet engine. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The particle size distribution is the same downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance of kd from the nozzle.

6. The apparatus for optimal design of liquid fuel injection section of a large scale scramjet engine as claimed in claim 5, wherein The first module includes the particle size distribution at different positions downstream of the nozzle for liquid fuel injection based on the liquid fuel injection section of the scaled scramjet engine, determines the position downstream of the nozzle where the particle size distribution suitable for ignition is located, and sets the distance k between the position downstream of the nozzle where the particle size distribution suitable for ignition is located and the nozzle of the scaled scramjet engine * d, k * greater than 0; The third module includes optimizing the nozzle diameter of the liquid fuel injection section of a large-scale scramjet engine. This makes the liquid fuel injection section of a large-scale scramjet engine downstream of the nozzle and at a distance from the nozzle... The location is downstream of the nozzle of the liquid fuel injection section of the scaled-down scramjet engine and at a distance k from the nozzle. * The same particle size distribution at point d indicates that the downstream of the nozzle in the liquid fuel injection section of the large-scale scramjet engine, at a distance of [missing information], is [missing information]. The location is set as the ignition point for a large-scale scramjet engine.

7. A computer system comprising a memory and a processor, the memory storing a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the large-scale scramjet engine liquid fuel injection section optimization design method as described in claim 1, 2, or 3.

8. A computer readable storage medium having stored thereon a computer program, characterized in that: The processor executes a computer program to implement the steps of the large-scale scramjet engine liquid fuel injection section optimization design method as described in claim 1, 2, or 3.

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