Self-ignition limit estimation method and device for full-flow staged combustion cycle engine

Abstract

The application discloses a self-ignition limit estimation method and device of a full-flow afterburning cycle engine, and relates to the technical field of engines, to solve the blank of the calculation of the self-ignition limit of the full-flow afterburning cycle engine in the prior art. The method comprises the following steps: performing three-dimensional numerical simulation on the self-ignition process of the full-flow afterburning cycle engine, and determining a target self-ignition limit working condition range; constructing a self-ignition index based on ignition delay data, pure mixed gas temperature and total gas flow; and matching the self-ignition index and the target self-ignition limit working condition range to obtain the self-ignition limit. The application is used for realizing the calculation of the self-ignition limit of the full-flow afterburning cycle engine.

Description

Technical Field

[0001] This invention relates to the field of engine technology, and in particular to a method and apparatus for estimating the autoignition limit of a full-flow afterburning cycle engine. Background Technology

[0002] The liquid oxygen-methane full-flow staged combustion cycle engine is an engine characterized by being non-toxic and environmentally friendly, highly reliable, high-performance, low-cost, easy to operate, and reusable. The full-flow staged combustion cycle it employs is one of the most advanced cycle methods in liquid rocket engines. It represents the highest level of liquid rocket engine technology in terms of performance, efficiency, and engineering complexity, and represents the development direction of aerospace propulsion technology. In the future, it will play a key role in important missions such as large-scale lunar and Mars exploration.

[0003] The full-flow afterburning cycle is a closed-loop cycle. Its core characteristic is that all propellant (fuel and oxidizer) passes through a pre-combustion chamber. Fuel and oxidizer enter their respective pre-combustion chambers, where partial combustion generates high-temperature combustion gases. These high-temperature combustion gases drive fuel turbopumps and oxidizer turbopumps, respectively, providing high-pressure propellant to the combustion chambers. The combustion gases generated in the pre-combustion chambers ultimately enter the main combustion chamber, where they mix and burn with the remaining propellant to generate thrust. This design maximizes propellant energy utilization efficiency while avoiding propellant waste found in open-loop cycles.

[0004] The thrust chamber of the liquid oxygen-methane full-flow afterburning cycle engine is a gas-gas combustion chamber. The high-temperature oxygen-enriched gas generated by the oxygen-enriched generator and the high-temperature fuel-enriched gas generated by the fuel-enriched generator are mixed in the thrust chamber through a coaxial shear nozzle for combustion.

[0005] Existing designs generally employ flare ignition, with the additional energy provided by the flare ensuring ignition of the thrust chamber under a wide range of inflow conditions. However, the igniter may experience starting problems, and its significant dead weight can degrade engine performance. Considering that both the oxygen-rich and fuel-rich gases at the thrust chamber inlet of a full-flow staged combustion cycle are at high temperatures, combustion may occur as soon as the two high-temperature gases mix. If self-ignition is possible, the thrust chamber flare igniter can be eliminated, simplifying the system structure and improving system reliability. However, eliminating the ignition device also has negative consequences; when the high-temperature gas flow is near or below the ignition limit, ignition failure may occur, severely impacting the launch mission. Furthermore, to meet reusability requirements, the engine must have multiple start-ups and deep throttling capabilities, requiring stable ignition even at minimal gas temperature and flow rates. Therefore, before designing a self-ignition scheme for a full-flow staged combustion cycle engine, the engine's self-ignition limit needs to be calculated. Summary of the Invention

[0006] The purpose of this invention is to provide a method and apparatus for estimating the autoignition limit of a full-flow staged combustion cycle engine, which is used to calculate the autoignition limit of the full-flow staged combustion cycle engine.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] In a first aspect, the present invention provides a method for estimating the self-ignition limit of a full-flow afterburning cycle engine, comprising:

[0009] A three-dimensional numerical simulation of the autoignition process of a full-flow afterburning cycle engine was performed to determine the target autoignition limit range.

[0010] Based on ignition delay data, pure mixed gas temperature, and total gas flow rate, an auto-ignition index is constructed.

[0011] The self-ignition index and the target self-ignition limit operating condition range are matched to obtain the self-ignition limit.

[0012] In one optional embodiment, the three-dimensional numerical simulation of the autoignition process of the full-flow afterburning cycle engine to obtain the target autoignition limit range includes:

[0013] Obtain the first set of operating condition combinations; the operating factors in each operating condition combination in the first set of operating condition combinations must include at least liquid oxygen flow rate and methane flow rate;

[0014] A three-dimensional numerical calculation model is constructed based on the computational domain of the full-flow afterburning cycle engine;

[0015] Based on the first set of operating conditions, the three-dimensional numerical calculation model is used to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each operating condition combination to obtain the first temperature field output data under each operating condition.

[0016] The output data of the first temperature field is analyzed to determine whether each working condition combination achieves self-ignition, and the first judgment result is obtained.

[0017] Based on the first judgment result, the first self-ignition limit condition range is determined;

[0018] Based on the first self-ignition limit operating condition range, the target self-ignition limit operating condition range is determined.

[0019] In an optional embodiment, determining the target self-ignition limit range based on the first self-ignition limit range includes:

[0020] Select a second set of operating condition combinations from the first self-ignition limit operating condition range;

[0021] Based on the second set of operating conditions, the three-dimensional numerical calculation model is used to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each operating condition combination to obtain the second temperature field output data under each operating condition.

[0022] The output data of the second temperature field is analyzed to determine whether self-ignition is achieved for each operating condition combination, and the second judgment result is obtained.

[0023] Based on the second judgment result, the range of the second self-ignition limit condition is determined;

[0024] If the second self-ignition limit operating condition range is within the preset operating condition range, then the second self-ignition limit operating condition range is determined as the target self-ignition limit operating condition range.

[0025] If the second self-ignition limit operating condition range is outside the preset operating condition range, continue to determine a new set of operating condition range combinations and perform three-dimensional numerical simulation calculations until the new set of operating condition range combinations is within the preset operating condition range.

[0026] In one optional embodiment, constructing the self-ignition index based on ignition delay data, pure mixture gas temperature, and total gas flow rate includes:

[0027] Based on the ignition delay data, a first quantitative relationship is constructed; the first quantitative relationship is the quantitative relationship between ignition delay and pressure, temperature, and equivalence ratio.

[0028] The self-ignition index is determined based on the pure mixed gas temperature, the total gas flow rate, and the first quantitative relationship.

[0029] In an optional embodiment, constructing the first quantitative relationship based on the ignition delay data includes:

[0030] Based on the ignition delay data, the reaction rate constant was determined using the Arenius equation.

[0031] In an optional embodiment, determining the self-ignition index based on the pure gas mixture temperature, the total gas flow rate, and the first quantitative relationship includes:

[0032] A second quantitative relationship is established, which is the quantitative relationship between the chamber pressure of the thrust chamber in the full-flow afterburning cycle engine and the total gas flow rate, the temperature of the pure mixed gas, and the throat area of ​​the thrust chamber;

[0033] Ignoring the equivalence ratio in the first quantitative relationship, a third quantitative relationship is determined based on the first and second quantitative relationships; the third quantitative relationship is a quantitative relationship between ignition delay and total gas flow rate and pure mixed gas temperature.

[0034] The third quantitative relationship is determined as the self-ignition index.

[0035] In one optional embodiment, the total gas flow rate is the sum of the oxygen-enriched gas flow rate and the fuel-enriched gas flow rate;

[0036] The calculation process for the temperature of the pure mixed gas is as follows:

[0037] Formula used:

[0038]

[0039] The temperature of the pure gas mixture is obtained by weighted calculation; where T mix Q1 is the temperature of the pure mixed gas, Q2 is the flow rate of the oxygen-enriched gas, T1 is the temperature of the oxygen-enriched gas, and T2 is the temperature of the oxygen-enriched gas.

[0040] In one optional embodiment, the calculation process for the ignition delay data is as follows:

[0041] Construct a zero-dimensional isobaric adiabatic combustion model;

[0042] Using the maximum rate of change of temperature over time as the criterion for judging ignition delay, a zero-dimensional isobaric adiabatic combustion model is used to calculate different operating parameters to obtain the ignition delay data; the operating parameters include at least pressure, temperature and equivalence ratio; the ignition delay data is the change relationship data characterizing the relationship between ignition delay and multiple operating parameters.

[0043] In one optional embodiment, matching the self-ignition index with the self-ignition limit operating range to determine the self-ignition limit includes:

[0044] By matching the self-ignition index and the self-ignition limit operating range, at least one self-ignition critical index value is obtained.

[0045] The at least one self-ignition critical index value is determined as the self-ignition limit.

[0046] The beneficial effects of this invention are as follows: Compared with the prior art, this invention provides a method for estimating the autoignition limit of a full-flow staged combustion cycle engine. By performing a three-dimensional numerical simulation of the autoignition process of the full-flow staged combustion cycle engine, the target autoignition limit operating condition range is determined; based on ignition delay data, pure mixture gas temperature, and total gas flow, an autoignition index is constructed; and by matching the autoignition index with the target autoignition limit operating condition range, the autoignition limit is obtained, thus enabling the calculation of the autoignition limit of a full-flow staged combustion cycle engine.

[0047] Secondly, the present invention also provides a self-ignition limit estimation device for a full-flow afterburning cycle engine, comprising:

[0048] The simulation calculation module is used to perform three-dimensional numerical simulation of the autoignition process of the full-flow afterburning cycle engine to obtain the target autoignition limit operating condition range.

[0049] The first determination module is used to construct self-ignition indicators based on ignition delay data, pure mixed gas temperature and total gas flow.

[0050] The second determining module is used to match the self-ignition index with the target self-ignition limit operating condition range to determine the self-ignition limit. Attached Figure Description

[0051] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0052] Figure 1 One of the flowcharts for estimating the self-ignition limit of a full-flow afterburning cycle engine provided as an embodiment of the present invention;

[0053] Figure 2 A second schematic flowchart of a method for estimating the self-ignition limit of a full-flow afterburning cycle engine, provided as an embodiment of the present invention;

[0054] Figure 3 A flowchart illustrating the self-ignition limit estimation method for a full-flow afterburning cycle engine, as provided in an embodiment of the present invention, is shown in Figure 3.

[0055] Figure 4 A flowchart illustrating the self-ignition limit estimation method for a full-flow afterburning cycle engine, as provided in an embodiment of the present invention, is shown in Figure 4.

[0056] Figure 5 A schematic diagram of the self-ignition limit estimation device for a full-flow afterburning cycle engine provided in an embodiment of the present invention. Detailed Implementation

[0057] To facilitate a clear description of the technical solutions in the embodiments of the present invention, the terms "first" and "second" are used to distinguish identical or similar items with essentially the same function and effect. For example, the first threshold and the second threshold are merely used to distinguish different thresholds and do not limit their order. Those skilled in the art will understand that the terms "first" and "second" do not limit the quantity or execution order, and that the terms "first" and "second" are not necessarily different.

[0058] It should be noted that in this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0059] In this invention, "at least one" means one or more, and "more than one" means two or more. "And / or" describes the relationship between the associated objects, indicating that three relationships can exist.

[0060] like Figure 1 As shown, this embodiment of the invention provides a method for estimating the self-ignition limit of a full-flow staged combustion cycle engine, which may include:

[0061] Step 100: Perform a three-dimensional numerical simulation of the autoignition process of the full-flow afterburning cycle engine to determine the target autoignition limit range.

[0062] The full-flow afterburning cycle engine in this embodiment is a liquid oxygen-methane full-flow afterburning cycle engine.

[0063] Specifically, a scaled-down experimental specimen can be selected as a simplified structure of the thrust chamber for simulation. The injection sequence can also be simplified to simultaneous injection from the start time. The entire self-ignition process under different working conditions can be calculated through three-dimensional numerical simulation, and the self-ignition limit range of the thrust chamber can be determined based on this.

[0064] Before conducting the simulation, a three-dimensional numerical calculation model can be established based on the pre-determined computational domain of the full-flow afterburning cycle engine.

[0065] Some existing technologies may use simplified two-dimensional models or oversimplify the computational domain, which cannot fully and accurately reflect the complex combustion phenomena inside a full-flow afterburning cycle engine.

[0066] The three-dimensional numerical calculation model in this embodiment can more realistically simulate the actual situation inside the engine. Taking into account the flow and heat transfer characteristics in various directions, it captures complex flow structures that cannot be represented by the two-dimensional model, such as vortices and secondary flows, thus providing a more accurate basis for subsequent simulation analysis.

[0067] The simulation process using a three-dimensional numerical computation model may include the following steps:

[0068] 1) Considering the supercritical characteristics, the physical properties of the fuel gas can be calculated using the real gas equation of state;

[0069] In existing technologies, the ideal gas law is often used to calculate the physical properties of fuel gas. The ideal gas law assumes that there are no intermolecular forces and that the molecules themselves do not occupy volume. This deviates significantly from the actual situation under supercritical conditions and cannot accurately describe the physical properties of fuel gas.

[0070] The real gas state equation in this embodiment takes into account the interaction forces between gas molecules and the molecular volume, which can more accurately calculate the physical properties of gas under supercritical conditions such as density, specific heat, and viscosity, improve the accuracy of simulation results, and better match the high-pressure and high-temperature supercritical working environment inside the full-flow afterburning cycle engine.

[0071] 2) To accurately simulate the ignition process, a detailed methane combustion mechanism, such as GRI3.0, can be used to simulate the ignition process.

[0072] The simplified combustion mechanism used in existing technologies cannot describe in detail the complex chemical reactions in the methane combustion process. The simulation of the ignition process is not accurate enough and cannot capture some key intermediate reactions and the generation and consumption of free radicals.

[0073] The detailed methane combustion mechanism of GRI3.0 in this embodiment contains a large amount of chemical reaction and species information, which can more accurately simulate the methane combustion process, including key phenomena such as ignition delay and flame propagation, and provide a more accurate chemical kinetic basis for studying the autoignition process.

[0074] 3) A separated eddy turbulence model is adopted;

[0075] Traditional turbulence models may have limitations when simulating complex flows, either failing to accurately capture the large-scale structure of turbulence or requiring excessively high mesh sizes and computational costs.

[0076] The separated eddy turbulence model in this embodiment combines the advantages of the Reynolds-averaged Navier-Stokes (RANS) model and the Large Eddy Simulation (LES). It can reduce the amount of mesh required while ensuring a certain level of computational accuracy. At the same time, it can better simulate large-scale separation and vortex structures in turbulence and more accurately reflect the influence of turbulence on combustion.

[0077] 4) Combined with a separated vortex model, combustion adopts a finite rate model;

[0078] Existing technologies may employ simple, rapid reaction models when simulating combustion, assuming that the combustion reaction is completed instantaneously and ignoring the influence of chemical reaction rates. This does not match the actual situation during ignition and combustion.

[0079] The finite rate model in this embodiment takes into account the rate of chemical reaction, and can more accurately simulate the consumption of reactants and the generation of products during combustion. When used in conjunction with the separated eddy turbulence model, it can better capture the interaction between turbulence and combustion, and improve the accuracy of the simulation.

[0080] 5) Apply boundary conditions: use a flow inlet and a pressure outlet.

[0081] 6) Set up the transient solver and discretization method, and set the transient step size;

[0082] 7) Output the temperature field every 1ms;

[0083] 8) Determine whether self-ignition can be achieved based on whether there is a sudden increase in temperature.

[0084] A sudden increase in temperature is a clear characteristic of self-ignition. Judging whether self-ignition can be achieved based on whether a sudden increase in temperature occurs is an intuitive, simple, and effective method that can accurately determine the timing of self-ignition and provide important basis for studying engine ignition performance.

[0085] Finally, the above steps are performed sequentially for different operating conditions to obtain the target self-ignition limit operating condition range.

[0086] Different operating conditions can be described using different operating parameters. For example, the operating parameters in this embodiment may include temperature, flow rate, and pressure. Flow rate may include oxygen-enriched gas flow rate and fuel-enriched gas flow rate, and temperature may include oxygen-enriched gas temperature and fuel-enriched gas temperature.

[0087] Step 200: Construct self-ignition indices based on ignition delay data, pure mixed gas temperature, and total gas flow rate;

[0088] Understandably, the concept involved in ignition delay data refers to the time interval from the start of fuel and oxidizer mixing to the occurrence of a combustion reaction.

[0089] Ignition delay data is data that characterizes the relationship between ignition delay and multiple operating parameters. These multiple operating parameters include at least temperature, pressure, and equivalence ratio (equivalence ratio is the mass ratio of fuel to oxidant). They may also include fuel characteristics, mixture turbulence, ignition energy, combustion chamber structure, etc.

[0090] The calculation process for ignition delay data includes at least A) and B).

[0091] A) Construct a zero-dimensional isobaric adiabatic combustion model;

[0092] In this embodiment, the zero-dimensional isobaric adiabatic combustion model simplifies the model structure, reduces computational load and time, and can quickly obtain approximate combustion results under different operating conditions, thus improving research efficiency, while maintaining a certain level of computational accuracy. Furthermore, it focuses on the core parameters of the combustion process, avoiding interference from excessive irrelevant factors and highlighting the influence of key factors such as pressure, temperature, and equivalence ratio on ignition delay.

[0093] B) Using the maximum rate of change of temperature over time as the criterion for judging ignition delay, a zero-dimensional isobaric adiabatic combustion model is used to calculate different operating parameters to obtain ignition delay data.

[0094] In this embodiment, using the maximum rate of temperature change over time as the criterion for determining ignition delay is more objective and accurate. The maximum rate of temperature change reflects the moment when heat is released most rapidly during combustion, which is consistent with the essence of ignition—the start of a violent chemical reaction and the rapid release of energy—and can more accurately capture the starting point of ignition.

[0095] Furthermore, this embodiment systematically calculates the ignition delay under different pressures, temperatures, and equivalence ratios, enabling a comprehensive understanding of the influence of these factors on ignition delay and providing a rich data foundation for establishing accurate quantitative relationships. Analysis of large amounts of data can reveal commonalities and differences under different operating conditions, thereby more accurately describing the relationship between ignition delay and various factors.

[0096] It should be noted that, in order to accurately quantify the relevant characteristics of self-ignition in this embodiment, the self-ignition index is constructed as a quantitative relationship between ignition delay and total gas flow rate and pure mixed gas temperature, so as to facilitate clear quantification and in-depth study, which is explained in detail below.

[0097] Step 300: Match the self-ignition index with the target self-ignition limit operating range to obtain the self-ignition limit.

[0098] The self-ignition limit refers to the boundary state or operating range from non-self-ignition to self-ignition capability during the self-ignition process of a liquid oxygen-methane full-flow afterburning cycle engine. The purpose of calculating self-ignition in this embodiment is threefold: First, clarifying the ignition limit helps in a deeper understanding of the combustion chemical reaction mechanism of liquid oxygen-methane under the complex conditions of a full-flow afterburning cycle. By determining the limiting operating conditions, we can know under what conditions the mixing and reaction of liquid oxygen and methane can transition from a stable unburned state to a violent combustion state. Second, determining the ignition limit requires the use of various numerical simulation models and experimental methods. Through continuous comparison and verification with actual conditions, the accuracy and reliability of existing models can be tested, problems can be identified and improved, thereby enhancing the simulation and prediction capabilities of the combustion process. Third, it is crucial for the design of liquid oxygen-methane engines. Knowing the ignition limit range allows designers to rationally select engine operating parameters, ensuring reliable ignition and start-up under various operating conditions, avoiding problems such as self-ignition failure or unstable combustion, and improving engine performance and reliability. For example, when designing the engine's fuel supply system and combustion chamber, the appropriate liquid oxygen and methane flow ranges, injection methods, etc., can be determined based on the ignition limit to ensure that the fuel mixes and burns under optimal conditions during engine start-up and operation. Fourth, it helps in developing safe operating procedures and operating ranges for the engine, preventing safety accidents such as accidental flameout or detonation, and ensuring the safe and stable operation of the engine. Fifth, accurately determining the ignition limit can help optimize engine operating costs. Under the premise of ensuring normal engine ignition and stable combustion, by reasonably adjusting the operating conditions to approach the ignition limit while maintaining a safe distance, efficient fuel utilization can be achieved, fuel consumption can be reduced, and engine economy can be improved. At the same time, unnecessary testing and debugging work can be reduced, shortening the engine development cycle and lowering development costs.

[0099] As can be seen from the above, by performing three-dimensional numerical simulation of the autoignition process of a full-flow staged combustion cycle engine, the target autoignition limit range can be determined; based on ignition delay data, pure mixture temperature, and total gas flow, autoignition indices can be constructed; and by matching the autoignition indices with the target autoignition limit range, the autoignition limit can be obtained. This allows for the calculation of the autoignition limit of a full-flow staged combustion cycle engine and improves the calculation accuracy.

[0100] Optionally, step 100: Perform a three-dimensional numerical simulation of the autoignition process of the full-flow afterburning cycle engine to obtain the target autoignition limit range, which may specifically include:

[0101] Step 110: Obtain the first set of operating condition combinations; wherein, the operating condition factors in each operating condition combination in the first set of operating condition combinations include at least liquid oxygen flow rate and methane flow rate; that is, each operating condition combination includes at least two operating condition factors;

[0102] Step 120: Construct a three-dimensional numerical calculation model based on the computational domain of the full-flow afterburning cycle engine;

[0103] Step 130: Based on the first set of working conditions, use a three-dimensional numerical calculation model to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each working condition combination to obtain the first temperature field output data under each working condition.

[0104] Step 140: Analyze the output data of the first temperature field to determine whether each working condition combination achieves self-ignition and obtain the first judgment result;

[0105] Step 150: Based on the first judgment result, determine the first self-ignition limit operating condition range; wherein, the first self-ignition limit operating condition range is the operating condition range composed of the combination of operating conditions in which self-ignition is partially achieved and self-ignition is not partially achieved.

[0106] Specifically, the first judgment result includes three operating condition ranges. The first operating condition range is when all operating condition combinations achieve self-ignition. The second operating condition range is when all operating condition combinations do not achieve self-ignition. The third operating condition range is the operating condition range consisting of operating condition combinations other than the first and second operating condition ranges. In other words, the third operating condition range is the first self-ignition limit operating condition range: it is the operating condition range consisting of operating condition combinations that partially achieve self-ignition and partially fail to achieve self-ignition.

[0107] Step 160: Determine the target self-ignition limit range based on the first self-ignition limit range.

[0108] In a specific embodiment, steps 110-160 are described by way of example. For example, the operating parameters include liquid oxygen flow rate and methane flow rate. Before obtaining the first set of operating condition combinations, the operating condition range can be determined first: for example, the initial setting is that the variation range of liquid oxygen flow rate is 10 kg / s to 20 kg / s, and the variation range of methane flow rate is 5 kg / s to 10 kg / s.

[0109] To comprehensively study the self-ignition situation under different operating conditions, a series of operating points were selected within this range to form the first set of operating condition combinations. For example, six liquid oxygen flow rates were selected: 10 kg / s, 12 kg / s, 14 kg / s, 16 kg / s, 18 kg / s, and 20 kg / s. For each liquid oxygen flow rate, six methane flow rates were selected: 5 kg / s, 6 kg / s, 7 kg / s, 8 kg / s, 9 kg / s, and 10 kg / s. This results in a total of 6 × 6 = 36 different operating condition combinations, which constitute the first set of operating condition combinations.

[0110] For each operating condition combination, step 130 is performed, which involves calculating the fuel gas properties using the real gas equation of state, applying the detailed methane combustion mechanism using GRI 3.0, employing a separated eddy turbulence model and a finite-rate combustion model, applying boundary conditions at the flow inlet and pressure outlet, setting the transient solver, discretization method, and transient step size, and finally outputting the temperature field every 1 ms during the simulation. For example, for the operating condition of liquid oxygen flow rate of 12 kg / s and methane flow rate of 7 kg / s, a series of temperature field data are obtained after the simulation. By analyzing these data, it is determined whether a sudden temperature increase occurred under this operating condition, thereby determining whether self-ignition was achieved under this condition.

[0111] A comprehensive analysis of the simulation results for all 36 operating conditions revealed that when the liquid oxygen flow rate was less than 12 kg / s and the methane flow rate was less than 6 kg / s, self-ignition was not achieved at any of the operating conditions; however, when the liquid oxygen flow rate was greater than 16 kg / s and the methane flow rate was greater than 8 kg / s, self-ignition was achieved at all of the operating conditions. In the operating conditions where the liquid oxygen flow rate was between 12 kg / s and 16 kg / s and the methane flow rate was between 6 kg / s and 8 kg / s, some combinations of operating conditions achieved self-ignition, while others did not. These combinations of partially self-ignited and partially non-self-ignited operating conditions constitute the first self-ignition limit operating condition range.

[0112] Optionally, step 160: Based on the first self-ignition limit condition range, determine the target self-ignition limit condition range, which may specifically include:

[0113] Step 161: Select the second set of operating condition combinations from the first self-ignition limit operating condition range;

[0114] Step 162: Based on the second set of operating conditions, use a three-dimensional numerical calculation model to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each operating condition combination to obtain the second temperature field output data under each operating condition.

[0115] Step 163: Analyze the output data of the second temperature field to determine whether each operating condition combination achieves self-ignition and obtain the second judgment result;

[0116] Step 164: Based on the second judgment result, determine the second self-ignition limit condition range;

[0117] Similarly, the second judgment result also includes three operating condition ranges. The first operating condition range is when all operating condition combinations achieve self-ignition. The second operating condition range is when all operating condition combinations do not achieve self-ignition. The third operating condition range is the operating condition range consisting of operating condition combinations other than the first and second operating condition ranges. In other words, the third operating condition range is the second self-ignition limit operating condition range: it is the operating condition range consisting of operating condition combinations that partially achieve self-ignition and partially fail to achieve self-ignition.

[0118] Step 165: If the second self-ignition limit operating condition range is within the preset operating condition range, then the second self-ignition limit operating condition range is determined as the target self-ignition limit operating condition range.

[0119] Step 166: If the second self-ignition limit operating condition range is outside the preset operating condition range, continue to determine a new set of operating condition range combinations and perform three-dimensional numerical simulation calculations until the new set of operating condition range combinations is within the preset operating condition range.

[0120] In specific embodiment one, to obtain the narrowest possible range of self-ignition limiting conditions, the operating condition combinations within the first self-ignition limiting condition range can be further refined. For example, within the liquid oxygen flow rate range of 12 kg / s to 16 kg / s, intermediate values ​​such as 12.5 kg / s, 13.5 kg / s, 14.5 kg / s, and 15.5 kg / s can be selected. For each new liquid oxygen flow rate value, an intermediate value of methane flow rate between 6 kg / s and 8 kg / s can be selected, such as 6.5 kg / s, 7 kg / s, and 7.5 kg / s, and then three-dimensional numerical simulation calculations and analyses are performed again. After at least one such refinement and simulation analysis, the target self-ignition limiting condition range is finally determined. For example, when the liquid oxygen flow rate is between 13.2 kg / s and 15.8 kg / s and the methane flow rate is between 6.8 kg / s and 7.6 kg / s, it is exactly at the limit of self-ignition. Below this range, self-ignition is not possible; above this range, self-ignition is possible.

[0121] As can be seen from the above, in this implementation, by iteratively selecting and performing three-dimensional simulation calculations on the combination of operating conditions within the first self-ignition limit operating condition range, the self-ignition limit operating condition range can be further narrowed until the requirements of the preset operating condition range are met. This allows the target self-ignition limit operating condition range required by the designer to be finally selected, which is beneficial for calculating a more accurate self-ignition limit that is more in line with the actual operating conditions.

[0122] Optionally, step 200: Based on ignition delay data, pure mixture gas temperature, and total gas flow rate, construct self-ignition indices, specifically including:

[0123] Step 210: Based on the ignition delay data, construct the first quantitative relationship; the first quantitative relationship is the quantitative relationship between ignition delay and pressure, temperature, and equivalence ratio;

[0124] Step 210 further includes: determining the reaction rate constant using the Arenius equation based on the ignition delay data; and determining the first quantitative relationship based on the ignition delay data and the reaction rate constant.

[0125] Specifically, based on ignition delay data, the Arrhenius equation is used:

[0126]

[0127] Determine the reaction rate constant, where k is the reaction rate, A is the pre-exponential coefficient, P is the pressure, and n is the overall reaction order. The stoichiometric ratio is n1, where n1 is the fuel reaction order, and E is the stoichiometric ratio. a Let R be the activation energy, T be the gas constant, and T be the temperature. With constant pressure and equivalence ratio, the activation energy can be obtained from the reaction rates at different temperatures. With constant temperature and equivalence ratio, the overall reaction order can be obtained from the reaction rates at different pressures. With constant temperature and pressure, the fuel reaction order can be obtained from the reaction rates at different equivalence ratios. After determining the activation energy, overall reaction order, and fuel reaction order, the pre-exponential coefficient can be calculated from the reaction rate corresponding to any pressure, temperature, and equivalence ratio. This yields all the reaction rate constants.

[0128] Step 220: Determine the self-ignition index based on the pure mixed gas temperature, total gas flow rate, and the first quantitative relationship. The total gas flow rate is the sum of the oxygen-enriched gas flow rate and the fuel-enriched gas flow rate.

[0129] Understandably, before step 220, it is also necessary to obtain the combustion parameters of the combustion chamber, including the flow rate and temperature of the oxygen-enriched gas.

[0130] The calculation process for the temperature of a pure mixed gas is as follows:

[0131] Formula used:

[0132]

[0133] The temperature of the pure gas mixture is obtained by weighted calculation; where T mix Q1 is the temperature of the pure mixed gas, Q2 is the flow rate of the oxygen-enriched gas, T1 is the temperature of the oxygen-enriched gas, and T2 is the temperature of the oxygen-enriched gas.

[0134] By using a weighted calculation method to obtain the temperature of the pure mixed gas, a temperature that can comprehensively reflect the characteristics of each gas stream can be obtained, providing key operating parameters for subsequent steps such as constructing self-ignition indicators.

[0135] Step 220 includes: constructing a second quantitative relationship between the chamber pressure of the thrust chamber and the total gas flow rate, the pure gas mixture temperature, and the throat area of ​​the thrust chamber in the full-flow afterburning cycle engine; ignoring the equivalence ratio in the first quantitative relationship, determining a third quantitative relationship based on the first and second quantitative relationships; the third quantitative relationship is a quantitative relationship between ignition delay and the total gas flow rate and the pure gas mixture temperature; and determining the third quantitative relationship as the self-ignition index.

[0136] For example, the first quantitative relationship is specifically characterized by the corresponding first quantitative relationship formula (3):

[0137]

[0138] Where τ is the ignition delay, k is the reaction rate mentioned above, and P is the pressure. For the equivalence ratio, A, n, n1, and E a It is the reaction rate constant obtained through theoretical analysis and calculation.

[0139] For example, the second quantitative relationship is characterized by the corresponding second quantitative relationship formula (4):

[0140]

[0141] Among them, P 室 Let K0 be the chamber pressure of the thrust chamber, and Q be a constant related to gas properties and throat flow characteristics. total For the total gas flow rate, A throot This represents the area of ​​the throat of the thrust chamber.

[0142] Since the change in stoichiometry is small, the effect of stoichiometry on ignition delay can be ignored, that is, let the stoichiometry in formula (3) be negligible. A constant (e.g.) Then formula (3) becomes:

[0143]

[0144] P 室 Replace P in formula (5) and change T mix Replacing T in formula (5), formula (5) is transformed to obtain the third quantitative relationship (6):

[0145] (6)

[0147] Thus, the ignition delay τ is established with respect to the total gas flow rate Q. total and pure mixed gas temperature T mix The quantitative relationship is defined as the self-ignition index, for example, the third quantitative relationship is defined as the self-ignition index.

[0148] Step 300: Matching the self-ignition index and the self-ignition limit operating range to determine the self-ignition limit includes: matching the self-ignition index and the self-ignition limit operating range to obtain at least one self-ignition critical index value; and determining at least one self-ignition critical index value as the self-ignition limit.

[0149] Step 300 may specifically include:

[0150] 1) Calculate the self-ignition index values ​​under different working conditions (working parameters) using formula (6), which is also the third quantitative relationship.

[0151] The self-ignition index is a key quantity reflecting the ignition speed. As shown in formula (6), the self-ignition index is a function of the operating parameters (total gas flow rate and pure mixed gas temperature). By calculating different operating conditions such as pure mixed gas temperature and total gas flow rate, the corresponding self-ignition index values ​​are obtained. These self-ignition index values ​​are the basic data for subsequent analysis and judgment. Only by obtaining the self-ignition index under different operating conditions can we further judge the ease of ignition and the ignition limit.

[0152] 2) Sort the ignition difficulty of different operating conditions according to the value of the self-ignition index to obtain the sorted set of self-ignition indexes.

[0153] A higher self-ignition index value indicates that ignition is relatively faster and easier under that operating condition; conversely, a lower value indicates slower and more difficult ignition. By sorting the values, we can intuitively understand the ease or difficulty of ignition under different operating conditions, providing a preliminary reference and classification basis for subsequent judgment of ignition limits, and helping to quickly filter out possible ignition limit ranges from numerous operating conditions.

[0154] 3) Based on the target self-ignition limit operating condition range and the sorted set of self-ignition indicators, determine the self-ignition limit critical value. For example, if the self-ignition indicator is greater than the value, ignition is possible; if it is less than the value, ignition is not possible. Then, based on the self-ignition limit critical value, determine the self-ignition limit.

[0155] Based on the ranking of self-ignition indices obtained in the preceding steps, and combined with the results of three-dimensional calculations of the self-ignition process of a liquid oxygen-methane full-flow afterburning cycle engine, the ignition limit value is determined. Three-dimensional calculations can more realistically simulate the actual conditions within the engine. By comparing the self-ignition indices under different operating conditions with the results of ignition in the three-dimensional calculations, a critical self-ignition index value is identified. That is, when the self-ignition index is greater than this value, the three-dimensional calculations show that the engine can ignite; when it is less than this value, ignition is not possible. This critical value is the initially determined self-ignition limit, and it is the key node connecting the self-ignition index and the actual ignition situation.

[0156] Understandably, given that zero-dimensional analysis is relatively coarse, the self-ignition limit may not be a fixed value, but rather a range within which ignition may or may not occur. If the limit is above this range, ignition is certain; if it is below, ignition is certain. Based on the self-ignition limit (either a single value or a range), it is possible to determine whether ignition is possible under a given operating condition and to provide the maximum throttling depth for ignition constraints.

[0157] For example: Suppose ten operating conditions are calculated, and each operating condition is subjected to a pure mixing temperature T. mix Total flow Q total The corresponding ignition delays (τ1, τ2, ..., τ10) are calculated and sorted in ascending order (τ1 < τ2 < ... < τ10). If, during the matching process of the target self-ignition limit operating conditions, it is found that τ1 to τ4 can self-ignite while τ5 to τ10 cannot, then the self-ignition limit is considered to be within the range of τ4 to τ5. If the ignition delay of an operating condition is less than τ4, it can self-ignite; if it is greater than τ5, it cannot self-ignite.

[0158] In the second specific implementation method, combined with Figure 4 This paper elucidates the method for estimating the autoignition limit of a full-flow staged combustion cycle engine.

[0159] The first step is a three-dimensional simulation of the self-ignition process;

[0160] Determine whether self-ignition can be achieved; if yes, mark the condition as ignitable; if no, mark the condition as unignitable.

[0161] Based on the judgment results, the operating conditions are marked, the ignition boundary range is narrowed, and the ignition boundary marked in three dimensions is obtained;

[0162] In addition, zero-position isobaric adiabatic combustion was calculated to obtain ignition delay data;

[0163] Establish the first quantitative relationship between ignition delay and pressure, temperature, and equivalence ratio;

[0164] Construct a second quantitative relationship between room pressure and the temperature and total flow rate of the pure mixed gas;

[0165] Establish a functional relationship between the self-ignition index and the operating parameters, that is, construct the third quantitative relationship; the third quantitative relationship is the quantitative relationship between the self-ignition index and the total gas flow rate and the temperature of the pure mixed gas, and the third quantitative relationship is defined as the self-ignition index;

[0166] The ignition difficulty of each operating condition is ranked according to the self-ignition index.

[0167] By combining the self-ignition index and the ignition boundary marked by the three-dimensional results, the self-ignition limit is obtained;

[0168] Based on the self-ignition limit, determine whether self-ignition can be achieved under the operating conditions.

[0169] The autoignition limit estimation device for a full-flow staged combustion cycle engine provided by the present invention will be described below. The autoignition limit estimation device for a full-flow staged combustion cycle engine described below can be referred to in correspondence with the autoignition limit estimation method for a full-flow staged combustion cycle engine described above.

[0170] like Figure 5 As shown, this embodiment of the invention also provides an autoignition limit estimation device for a full-flow staged combustion cycle engine, used to implement the autoignition limit estimation method for a full-flow staged combustion cycle engine in any of the above embodiments. The autoignition limit estimation device for the full-flow staged combustion cycle engine may include:

[0171] The simulation calculation module 510 is used to perform three-dimensional numerical simulation of the autoignition process of the full-flow afterburning cycle engine to obtain the target autoignition limit operating condition range.

[0172] The first determining module 520 is used to construct self-ignition indicators based on ignition delay data, pure mixed gas temperature and total gas flow.

[0173] The second determining module 530 is used to match the self-ignition index with the target self-ignition limit operating condition range to determine the self-ignition limit.

[0174] The simulation calculation module 510 is specifically used for:

[0175] Obtain the first set of operating condition combinations; the operating factors in each operating condition combination in the first set of operating condition combinations must include at least liquid oxygen flow rate and methane flow rate;

[0176] A three-dimensional numerical calculation model is constructed based on the computational domain of the full-flow afterburning cycle engine;

[0177] Based on the first set of operating conditions, the three-dimensional numerical calculation model is used to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each operating condition combination to obtain the first temperature field output data under each operating condition.

[0178] The output data of the first temperature field is analyzed to determine whether each working condition combination achieves self-ignition, and the first judgment result is obtained.

[0179] Based on the first judgment result, the first self-ignition limit condition range is determined;

[0180] Based on the first self-ignition limit operating condition range, the target self-ignition limit operating condition range is determined.

[0181] The simulation calculation module 510 is specifically used for:

[0182] Select a second set of operating condition combinations from the first self-ignition limit operating condition range;

[0183] Based on the second set of operating conditions, the three-dimensional numerical calculation model is used to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each operating condition combination to obtain the second temperature field output data under each operating condition.

[0184] The output data of the second temperature field is analyzed to determine whether self-ignition is achieved for each operating condition combination, and the second judgment result is obtained.

[0185] Based on the second judgment result, the range of the second self-ignition limit condition is determined;

[0186] If the second self-ignition limit operating condition range is within the preset operating condition range, then the second self-ignition limit operating condition range is determined as the target self-ignition limit operating condition range.

[0187] If the second self-ignition limit operating condition range is outside the preset operating condition range, continue to determine a new set of operating condition range combinations and perform three-dimensional numerical simulation calculations until the new set of operating condition range combinations is within the preset operating condition range.

[0188] The second determining module 530 is specifically used for:

[0189] Based on the ignition delay data, a first quantitative relationship is constructed; the first quantitative relationship is the quantitative relationship between ignition delay and pressure, temperature, and equivalence ratio.

[0190] The self-ignition index is determined based on the pure mixed gas temperature, the total gas flow rate, and the first quantitative relationship.

[0191] The second determining module 530 is specifically used for:

[0192] Based on the ignition delay data, the reaction rate constant was determined using the Arenius equation.

[0193] Based on the ignition delay data and the reaction rate constant, the first quantitative relationship is determined.

[0194] The second determining module 530 is specifically used for:

[0195] A second quantitative relationship is established, which is the quantitative relationship between the chamber pressure of the thrust chamber in the full-flow afterburning cycle engine and the total gas flow rate, the temperature of the pure mixed gas, and the throat area of ​​the thrust chamber;

[0196] Ignoring the equivalence ratio in the first quantitative relationship, a third quantitative relationship is determined based on the first and second quantitative relationships; the third quantitative relationship is a quantitative relationship between ignition delay and total gas flow rate and pure mixed gas temperature.

[0197] The third quantitative relationship is determined as the self-ignition index.

[0198] The total gas flow rate is the sum of the oxygen-enriched gas flow rate and the fuel-enriched gas flow rate;

[0199] The calculation process for the temperature of the pure mixed gas is as follows:

[0200] Formula used:

[0201]

[0202] The temperature of the pure gas mixture is obtained by weighted calculation; where T mix Q1 is the temperature of the pure mixed gas, Q2 is the flow rate of the oxygen-enriched gas, T1 is the temperature of the oxygen-enriched gas, and T2 is the temperature of the oxygen-enriched gas.

[0203] The calculation process for ignition delay data is as follows:

[0204] Construct a zero-dimensional isobaric adiabatic combustion model;

[0205] Using the maximum rate of change of temperature over time as the criterion for judging ignition delay, a zero-dimensional isobaric adiabatic combustion model is used to calculate different operating parameters to obtain the ignition delay data; the operating parameters include at least pressure, temperature and equivalence ratio; the ignition delay data is the change relationship data characterizing the relationship between ignition delay and multiple operating parameters.

[0206] The second determining module 530 is specifically used for:

[0207] By matching the self-ignition index and the self-ignition limit operating range, at least one self-ignition critical index value is obtained.

[0208] The at least one self-ignition critical index value is determined as the self-ignition limit.

[0209] This invention also provides an electronic device, which may include a processor, a communication interface, a memory, and a communication bus, wherein the processor, the communication interface, and the memory communicate with each other via the communication bus. The memory stores a computer program that can be executed by the processor; when the processor runs the computer program, it can execute the self-ignition limit estimation method for the full-flow afterburning cycle engine in any of the above embodiments.

[0210] Furthermore, the logical instructions in the aforementioned memory can be implemented as software functional units and sold or used as independent products, and can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks.

[0211] In another aspect, the present invention also provides a non-transitory computer-readable storage medium storing instructions that, when executed, implement the self-ignition limit estimation method for the full-flow afterburning cycle engine in any of the above embodiments.

[0212] Although the invention has been described herein in conjunction with various embodiments, those skilled in the art will understand and implement other variations of the disclosed embodiments by reviewing the accompanying drawings, the disclosure, and the appended claims in carrying out the claimed invention. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0213] Although the invention has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made therein without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely exemplary descriptions of the invention as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if such modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include such modifications and modifications.

Claims

1. A method for estimating the self-ignition limit of a full-flow afterburning cycle engine, characterized in that, include: A three-dimensional numerical simulation of the autoignition process of a full-flow afterburning cycle engine was performed to determine the target autoignition limit range. Based on ignition delay data, pure mixed gas temperature, and total gas flow rate, an auto-ignition index is constructed. The self-ignition index and the target self-ignition limit operating condition range are matched to obtain the self-ignition limit; The self-ignition index, constructed based on ignition delay data, pure mixture gas temperature, and total gas flow rate, includes: Based on the ignition delay data, a first quantitative relationship is constructed; the first quantitative relationship is the quantitative relationship between ignition delay and pressure, temperature, and equivalence ratio. The self-ignition index is determined based on the pure mixed gas temperature, the total gas flow rate, and the first quantitative relationship; The step of constructing a first quantitative relationship based on the ignition delay data includes: Based on the ignition delay data, the reaction rate constant was determined using the Arenius equation. Based on the ignition delay data and the reaction rate constant, the first quantitative relationship is determined; The determination of the self-ignition index based on the pure mixed gas temperature, the total gas flow rate, and the first quantitative relationship includes: A second quantitative relationship is established, which is the quantitative relationship between the chamber pressure of the thrust chamber in the full-flow afterburning cycle engine and the total gas flow rate, the temperature of the pure mixed gas, and the throat area of ​​the thrust chamber; Let the equivalence ratio in the first quantitative relationship be a constant, and determine the third quantitative relationship based on the first and second quantitative relationships; the third quantitative relationship is a quantitative relationship between ignition delay and total gas flow rate and pure mixed gas temperature; The third quantitative relationship is determined as the self-ignition index.

2. The method for estimating the self-ignition limit of a full-flow afterburning cycle engine according to claim 1, characterized in that, The three-dimensional numerical simulation of the autoignition process of the full-flow afterburning cycle engine yields the target autoignition limit range, including: Obtain the first set of operating condition combinations; the operating factors in each operating condition combination in the first set of operating condition combinations include liquid oxygen flow rate and methane flow rate; A three-dimensional numerical calculation model is constructed based on the computational domain of the full-flow afterburning cycle engine; Based on the first set of operating conditions, the three-dimensional numerical calculation model is used to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each operating condition combination to obtain the first temperature field output data under each operating condition. The output data of the first temperature field is analyzed to determine whether each working condition combination achieves self-ignition, and the first judgment result is obtained. Based on the first judgment result, the first self-ignition limit condition range is determined; Based on the first self-ignition limit operating condition range, the target self-ignition limit operating condition range is determined.

3. The method for estimating the self-ignition limit of a full-flow staged combustion cycle engine according to claim 2, characterized in that, Determining the target self-ignition limit range based on the first self-ignition limit range includes: Select a second set of operating condition combinations from the first self-ignition limit operating condition range; Based on the second set of operating conditions, the three-dimensional numerical calculation model is used to perform three-dimensional numerical simulation calculations on the full-flow afterburning cycle engine under each operating condition combination to obtain the second temperature field output data under each operating condition. The output data of the second temperature field is analyzed to determine whether self-ignition is achieved for each operating condition combination, and the second judgment result is obtained. Based on the second judgment result, the range of the second self-ignition limit condition is determined; If the second self-ignition limit operating condition range is within the preset operating condition range, then the second self-ignition limit operating condition range is determined as the target self-ignition limit operating condition range. If the second self-ignition limit operating condition range is outside the preset operating condition range, continue to determine a new set of operating condition range combinations and perform three-dimensional numerical simulation calculations until the new set of operating condition range combinations is within the preset operating condition range.

4. The method for estimating the self-ignition limit of a full-flow afterburning cycle engine according to claim 1, characterized in that, The total gas flow rate is the sum of the oxygen-enriched gas flow rate and the fuel-enriched gas flow rate; The calculation process for the temperature of the pure mixed gas is as follows: Formula used: ； The temperature of the pure gas mixture is obtained by weighted calculation; wherein, The temperature of the pure mixed gas. For oxygen-enriched gas flow rate, To ensure sufficient fuel flow rate, The temperature of the oxygen-rich gas. The temperature of the fuel-rich gas.

5. The method for estimating the self-ignition limit of a full-flow afterburning cycle engine according to claim 1, characterized in that, The calculation process for ignition delay data is as follows: Construct a zero-dimensional isobaric adiabatic combustion model; Using the maximum rate of change of temperature over time as the criterion for judging ignition delay, a zero-dimensional isobaric adiabatic combustion model is used to calculate different operating parameters to obtain the ignition delay data; the operating parameters include at least pressure, temperature and equivalence ratio; the ignition delay data is the change relationship data characterizing the relationship between ignition delay and multiple operating parameters.

6. The method for estimating the self-ignition limit of a full-flow afterburning cycle engine according to claim 1, characterized in that, Matching the self-ignition parameters with the self-ignition limit range to determine the self-ignition limit includes: By matching the self-ignition index and the self-ignition limit operating range, at least one self-ignition critical index value is obtained. The at least one self-ignition critical index value is determined as the self-ignition limit.

7. A self-ignition limit estimation device for a full-flow afterburning cycle engine, characterized in that, include: The simulation calculation module is used to perform three-dimensional numerical simulation of the autoignition process of the full-flow afterburning cycle engine to obtain the target autoignition limit operating condition range. The first determination module is used to construct self-ignition indicators based on ignition delay data, pure mixed gas temperature and total gas flow. The second determining module is used to match the self-ignition index with the target self-ignition limit operating condition range to determine the self-ignition limit. The second determining module is specifically used to construct a first quantitative relationship based on the ignition delay data; the first quantitative relationship is a quantitative relationship between ignition delay and pressure, temperature, and equivalence ratio; The self-ignition index is determined based on the pure mixed gas temperature, the total gas flow rate, and the first quantitative relationship; Based on the ignition delay data, the reaction rate constant was determined using the Arenius equation. Based on the ignition delay data and the reaction rate constant, the first quantitative relationship is determined; A second quantitative relationship is established, which is the quantitative relationship between the chamber pressure of the thrust chamber in the full-flow afterburning cycle engine and the total gas flow rate, the temperature of the pure mixed gas, and the throat area of ​​the thrust chamber; Let the equivalence ratio in the first quantitative relationship be a constant, and determine the third quantitative relationship based on the first and second quantitative relationships; the third quantitative relationship is a quantitative relationship between ignition delay and total gas flow rate and pure mixed gas temperature; The third quantitative relationship is determined as the self-ignition index.

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