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

Abstract

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

Description

Technical Field

[0001] The present invention relates to the field of engine technology, and in particular to a method and device for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine. Background Art

[0002] The liquid oxygen-methane full-flow regenerative cycle engine is an engine with the characteristics of non-toxicity, environmental protection, high reliability, high performance, low cost, easy operation and reusability. The full-flow regenerative cycle it adopts is one of the most advanced cycle methods in current 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 main propulsion technology. In the future, it will play a key role in important missions such as large-scale lunar exploration and Mars exploration.

[0003] The full-flow regenerative combustion cycle is a closed cycle with the following key features: all propellants (fuel and oxidizer) pass through a preburner, where they enter their respective preburners and partially burn to generate high-temperature combustion gases. These high-temperature combustion gases drive the fuel and oxidizer turbopumps, respectively, providing high-pressure propellant to the combustion chambers. The combustion gases produced in the preburner ultimately enter the main combustion chamber, where they mix with the remaining propellant and burn to generate thrust. This design maximizes the energy efficiency of the propellant while avoiding the propellant waste associated with open cycles.

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

[0005] Existing designs commonly use a flare igniter. The additional energy provided by the flare ensures thrust chamber ignition over a wide range of incoming flow conditions, but the igniter can cause starting issues, and its inherent heavy weight can also reduce engine performance. Considering that both the oxygen-enriched and fuel-enriched gases at the thrust chamber inlet of a full-flow regenerative cycle are at high temperatures, the two high-temperature gases could potentially ignite upon mixing. If auto-ignition were possible, the thrust chamber flare igniter could be eliminated, simplifying the system architecture 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 failures may occur, seriously impacting the launch mission. Furthermore, to meet reusability requirements, the engine must also be capable of multiple starts and deep throttling, requiring stable ignition at minimal gas temperatures and flows. Therefore, before designing an auto-ignition solution for a full-flow regenerative cycle engine, the engine's auto-ignition limit must be calculated. Summary of the Invention

[0006] The object of the present invention is to provide a method and device for estimating the self-ignition limit of a full-flow secondary combustion cycle engine, so as to realize the calculation of the self-ignition limit of the full-flow secondary combustion cycle engine.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

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

[0009] Conduct three-dimensional numerical simulation of the auto-ignition process of a full-flow staged combustion cycle engine to determine the target auto-ignition limit operating range;

[0010] Construct the auto-ignition index based on the ignition delay data, pure mixed gas temperature and total gas flow rate;

[0011] The self-ignition index is matched with the target self-ignition limit operating range to obtain the self-ignition limit.

[0012] In an optional embodiment, the three-dimensional numerical simulation of the auto-ignition process of the full-flow secondary combustion cycle engine is performed to obtain the target auto-ignition limit operating condition range, including:

[0013] Acquire a first operating condition combination set; the operating condition factors in each operating condition combination in the first operating condition combination set include at least liquid oxygen flow rate and methane flow rate;

[0014] Constructing a three-dimensional numerical calculation model according to the calculation domain of the full-flow secondary combustion cycle engine;

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

[0016] Analyzing the first temperature field output data to determine whether each operating condition combination achieves self-ignition, thereby obtaining a first determination result;

[0017] determining a first self-ignition limit operating condition range based on the first judgment result;

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

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

[0020] Selecting a second operating condition combination set from the first self-ignition limit operating condition range;

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

[0022] Analyzing the second temperature field output data to determine whether each operating condition combination achieves self-ignition, thereby obtaining a second determination result;

[0023] determining a second self-ignition limit operating condition range based on the second judgment result;

[0024] If the second self-ignition limit operating condition range is within a preset operating condition range, determining the second self-ignition limit operating condition range 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 operating condition range combination set and perform three-dimensional numerical simulation calculations until the new operating condition range combination set is within the preset operating condition range.

[0026] In an optional embodiment, the self-ignition index is constructed based on the ignition delay data, the pure mixed gas temperature and the total gas flow rate, including:

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

[0028] The auto-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 a first quantitative relationship based on the ignition delay data includes:

[0030] Determining the reaction rate constant using the Arrhenius equation based on the ignition delay data;

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

[0032] Constructing a second quantitative relationship, wherein the second quantitative relationship is a quantitative relationship between the chamber pressure of the thrust chamber in the full-flow staged combustion cycle engine and the total flow rate of the fuel gas, the temperature of the pure mixed fuel gas, and the throat area of ​​the thrust chamber;

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

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

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

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

[0037] Using the formula:

[0038]

[0039] Perform weighted calculation to obtain the pure mixed gas temperature; wherein, T mix is the pure mixed gas temperature, Q1 is the oxygen-rich gas flow rate, Q2 is the fuel-rich gas flow rate, T1 is the oxygen-rich gas temperature, and T2 is the fuel-rich gas temperature.

[0040] In an optional embodiment, the calculation process of the ignition delay data is:

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

[0042] The maximum value of the temperature change rate over time is used as the judgment basis for ignition delay, and different operating parameters are calculated using a zero-dimensional isobaric adiabatic combustion model 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 that characterizes the relationship between the ignition delay and multiple operating parameters.

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

[0044] Matching the auto-ignition index with the auto-ignition limit operating range to obtain at least one auto-ignition critical index value;

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

[0046] The beneficial effects of the present invention are as follows: compared with the prior art, the present invention provides a method for estimating the self-ignition limit of a full-flow regenerative combustion cycle engine, which determines the target self-ignition limit operating condition range by performing three-dimensional numerical simulation of the self-ignition process of the full-flow regenerative combustion cycle engine; constructs a self-ignition index based on ignition delay data, pure mixed gas temperature and total gas flow; matches the self-ignition index with the target self-ignition limit operating condition range to obtain the self-ignition limit, which can realize the calculation of the self-ignition limit of the full-flow regenerative combustion cycle engine.

[0047] In a second aspect, the present invention further provides a device for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine, comprising:

[0048] A simulation calculation module is used to perform three-dimensional numerical simulation of the auto-ignition process of the full-flow secondary combustion cycle engine to obtain the target auto-ignition limit operating condition range;

[0049] A first determination module is used to construct a self-ignition index based on the ignition delay data, the pure mixed gas temperature and the total gas flow rate;

[0050] The second determination module is used to match the self-ignition index with the target self-ignition limit operating condition range to determine the self-ignition limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0052] Figure 1 One of the flow charts of a method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine provided by one embodiment of the present invention;

[0053] Figure 2 A second flow chart of a method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine provided by one embodiment of the present invention;

[0054] Figure 3 A third flow chart of a method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine provided by one embodiment of the present invention;

[0055] Figure 4 A fourth flow chart of a method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine provided by one embodiment of the present invention;

[0056] Figure 5 A schematic structural diagram of a device for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine provided by one embodiment of the present invention. DETAILED DESCRIPTION

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

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

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

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

[0061] Step 100: performing a three-dimensional numerical simulation of the auto-ignition process of the full-flow staged combustion cycle engine to determine a target auto-ignition limit operating range;

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

[0063] Specifically, a scaled-down test piece can be selected as a simplified structure of the thrust chamber for simulation, and the filling sequence can also be simplified to simultaneous filling from the starting moment. The entire self-ignition process under different working conditions is calculated through three-dimensional numerical simulation, and this is used as a basis to judge the self-ignition limit range of the thrust chamber.

[0064] Before simulation, a three-dimensional numerical calculation model can be established based on a predetermined calculation domain of the full-flow staged combustion cycle engine.

[0065] Some existing technologies may adopt simplified two-dimensional models or over-simplify the calculation domain, which cannot fully and accurately reflect the complex combustion phenomena inside the full-flow regenerative cycle engine.

[0066] The three-dimensional numerical calculation model in this embodiment can more realistically simulate the actual conditions inside the engine, taking into account the flow and heat transfer characteristics in all directions, and capturing complex flow structures that cannot be reflected in the two-dimensional model, such as vortices and secondary flows, thereby providing a more accurate basis for subsequent simulation analysis.

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

[0068] 1) Considering the supercritical characteristics, the real gas state equation can be used to calculate the gas properties;

[0069] In the existing technology, the ideal gas state equation is often used to calculate the physical properties of the gas. The ideal gas state equation assumes that there is no interaction force between gas molecules and the molecules themselves do not occupy volume. This deviates greatly from the actual situation under supercritical conditions and cannot accurately describe the physical properties of the gas.

[0070] The real gas state equation in this embodiment takes into account the interaction force between gas molecules and the molecular volume, and can more accurately calculate the physical properties of the fuel gas in the supercritical state, such as density, specific heat, and viscosity, thereby improving the accuracy of the simulation results and being more consistent with the high-pressure, high-temperature supercritical working environment inside the full-flow regenerative 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, such as GRI3.0 in this embodiment, contains a large amount of chemical reaction and species information, and can more accurately simulate the methane combustion process, including key phenomena such as ignition delay and flame propagation, providing a more accurate chemical kinetic basis for studying the auto-ignition process.

[0074] 3) Using the detached eddy turbulence model;

[0075] Traditional turbulence models may have limitations when simulating complex flows. They may fail to accurately capture the large-scale structure of turbulence or have too high mesh requirements and high computational costs.

[0076] The detached 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 demand for grid volume while ensuring a certain level of calculation accuracy. At the same time, it can better simulate the large-scale separation and vortex structure in turbulence, and more accurately reflect the impact of turbulence on combustion.

[0077] 4) The combustion model is matched with the detached vortex model and the finite rate model is adopted;

[0078] Existing technologies may use a simple rapid reaction model when simulating combustion, assuming that the combustion reaction is completed instantaneously and ignoring the influence of the chemical reaction rate. This is inconsistent with the actual situation in the actual ignition and combustion process.

[0079] The finite rate model in this embodiment takes into account the rate of chemical reactions and can more accurately simulate the consumption of reactants and the generation of products during the combustion process. When used in conjunction with the detached 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, the inlet is a flow inlet, and the outlet is a pressure outlet;

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

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

[0083] 8) Whether self-ignition can be achieved is determined by whether there is a sudden increase in temperature.

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

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

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

[0087] Step 200: Constructing a self-ignition index based on the ignition delay data, the pure mixed gas temperature and the total gas flow rate;

[0088] It is understood that the concept of ignition delay involved in the ignition delay data refers to the time interval from the beginning of the mixing of fuel and oxidant to the occurrence of the combustion reaction.

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

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

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

[0092] In this example, the zero-dimensional isobaric adiabatic combustion model simplifies the model structure, reduces computational effort and time, and rapidly obtains approximate combustion results under various operating conditions, improving research efficiency. Furthermore, it focuses on the core parameters of the combustion process, avoiding interference from excessive irrelevant factors and highlighting the impact of key factors such as pressure, temperature, and equivalence ratio on ignition delay.

[0093] B) Using the maximum value of the temperature change rate over time as the judgment basis for 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 temperature change rate over time as the ignition delay judgment criterion is more objective and accurate. The maximum temperature change rate reflects the fastest heat release point during the combustion process. This aligns with the essence of ignition—the onset of a violent chemical reaction and the rapid release of energy—and more accurately captures the starting point of ignition.

[0095] Furthermore, this embodiment systematically calculates ignition delay under various pressures, temperatures, and equivalence ratios, enabling a comprehensive understanding of the impact of these factors on ignition delay and providing a rich data foundation for the subsequent development of accurate quantitative relationships. By analyzing this extensive data, commonalities and differences across different operating conditions can be identified, leading to a more accurate description of 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 the ignition delay and the total gas flow rate and the pure mixed gas temperature, so as to facilitate clear quantification and in-depth research, 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 autoignition limit refers to the boundary state or operating condition range between the inability to autoignite and the ability to autoignite during the autoignition process of a liquid oxygen-methane full-flow staged combustion cycle engine. The purpose of calculating autoignition in this embodiment is: First, clarifying the ignition limit facilitates a deeper understanding of the combustion chemical reaction mechanisms of liquid oxygen-methane under the complex conditions of a full-flow staged combustion cycle. By determining the limiting operating conditions, it is possible to determine under what conditions the mixing and reaction of liquid oxygen and methane can transition from a stable, unburned state to a vigorous combustion state. Second, determining the ignition limit requires the use of various numerical simulation models and experimental methods. By continuously comparing and validating the results with actual conditions, the accuracy and reliability of existing models can be verified, and any model flaws identified and improved, thereby improving 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 to ensure reliable engine ignition and start-up under various operating conditions, avoiding problems such as autoignition failure or unstable combustion, and improving engine performance and reliability. For example, when designing an engine's fuel supply system and combustion chamber, the appropriate liquid oxygen and methane flow rate ranges and injection methods can be determined based on the ignition limit to ensure optimal fuel mixing and combustion during engine startup and operation. Fourthly, this helps establish safe operating procedures and operating ranges for the engine, preventing safety incidents such as unexpected flameouts or deflagrations and ensuring safe and stable engine operation. Fifth, accurately understanding the auto-ignition limit can help optimize engine operating costs. While ensuring normal engine ignition and stable combustion, by rationally adjusting 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. This can also reduce unnecessary testing and debugging, shortening the engine's development cycle and reducing R&D costs.

[0099] From the above content, it can be seen that by performing a three-dimensional numerical simulation of the auto-ignition process of the full-flow regenerative combustion cycle engine, the target auto-ignition limit operating range is determined; based on the ignition delay data, the pure mixture gas temperature and the total gas flow rate, the auto-ignition index is constructed; and the auto-ignition limit is obtained by matching the auto-ignition index with the target auto-ignition limit operating range. This can realize the calculation of the auto-ignition limit of the full-flow regenerative combustion cycle engine and improve the calculation accuracy.

[0100] Optionally, step 100: performing a three-dimensional numerical simulation on the auto-ignition process of the full-flow secondary combustion cycle engine to obtain a target auto-ignition limit operating condition range may specifically include:

[0101] Step 110: Obtain a first operating condition combination set; wherein the operating condition factors in each operating condition combination in the first operating condition combination set 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: constructing a three-dimensional numerical calculation model according to the calculation domain of the full-flow staged combustion cycle engine;

[0103] Step 130: Based on the first operating condition combination set, a three-dimensional numerical calculation model is used to perform a three-dimensional numerical simulation calculation on the full-flow regenerative cycle engine under each operating condition combination to obtain first temperature field output data under each operating condition;

[0104] Step 140: Analyze the first temperature field output data to determine whether each operating condition combination achieves self-ignition, and obtain a first determination result;

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

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

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

[0108] In the first specific embodiment, steps 110 to 160 are described as an example. For example, the operating condition parameters include liquid oxygen flow rate and methane flow rate. Before obtaining the first operating condition combination set, the operating condition range can be determined: for example, the liquid oxygen flow rate range is initially set to 10 kg / s to 20 kg / s, and the methane flow rate range is initially set to 5 kg / s to 10 kg / s.

[0109] To comprehensively study auto-ignition under different operating conditions, a series of operating conditions within this range were selected to form the first operating condition combination set. 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 value, 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 resulted in a total of 6 × 6 = 36 different operating condition combinations, which constituted the first operating condition combination set.

[0110] For each operating condition combination, step 130 is performed. The real gas equation of state is used to calculate gas properties. The GRI 3.0 detailed methane combustion mechanism is used, along with the detached eddy turbulence model and the finite rate combustion model. Boundary conditions for the flow inlet and pressure outlet are applied, and a transient solver, discretization method, and transient step size are set. Finally, the temperature field is output every 1ms during the simulation. For example, for an operating condition with a liquid oxygen flow rate of 12 kg / s and a methane flow rate of 7 kg / s, a series of temperature field data is obtained after the simulation. This data is analyzed to determine whether a sudden temperature increase occurs under these operating conditions, thereby confirming whether auto-ignition has occurred under these conditions.

[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, no self-ignition was achieved at any operating point. 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 operating points. Furthermore, for operating conditions with liquid oxygen flow rates between 12 kg / s and 16 kg / s and methane flow rates between 6 kg / s and 8 kg / s, some combinations achieved self-ignition while others did not. These combinations of operating conditions, where some achieved self-ignition while others did not, constitute the first self-ignition limit operating range.

[0112] Optionally, step 160: determining a target self-ignition limit operating condition range based on the first self-ignition limit operating condition range may specifically include:

[0113] Step 161: Selecting a second operating condition combination set from the first auto-ignition limit operating condition range;

[0114] Step 162: Based on the second operating condition combination set, a three-dimensional numerical calculation model is used to perform a three-dimensional numerical simulation calculation on the full-flow regenerative cycle engine under each operating condition combination to obtain second temperature field output data under each operating condition;

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

[0116] Step 164: Determine a second auto-ignition limit operating condition range based on the second judgment result;

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

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

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

[0120] In the first specific embodiment, in order to obtain the narrowest possible self-ignition limit operating condition range, the operating condition combinations within the first self-ignition limit operating 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 are selected. For each new liquid oxygen flow rate value, an intermediate methane flow rate between 6 kg / s and 8 kg / s, such as 6.5 kg / s, 7 kg / s, and 7.5 kg / s, is selected, and three-dimensional numerical simulation calculations and analysis are performed again. After at least one such refinement and simulation analysis, the target self-ignition limit operating condition range is ultimately 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, the self-ignition limit state is exactly reached. When the liquid oxygen flow rate is below this range, the self-ignition state cannot be achieved, but when the methane flow rate is above this range, the self-ignition state can be achieved.

[0121] From the above content, it can be seen that in this implementation, by iteratively selecting and three-dimensionally simulating the operating condition combinations 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. The target self-ignition limit operating condition range required by the designer can finally be selected, which is conducive to calculating a self-ignition limit that is more in line with actual operating conditions and more accurate.

[0122] Optionally, step 200: constructing a self-ignition index based on the ignition delay data, the pure mixed gas temperature and the total gas flow rate, specifically including:

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

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

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

[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 total reaction order. is the equivalence ratio, n1 is the fuel reaction order, E a is the activation energy, R is the gas constant, and T is the temperature. Under constant pressure and equivalence ratio, the activation energy can be obtained from the reaction rates at different temperatures. Under constant temperature and equivalence ratio, the total reaction order can be obtained from the reaction rates at different pressures. Under constant temperature and pressure, the fuel reaction order can be obtained from the reaction rates at different equivalence ratios. After determining the activation energy, total reaction order, and fuel reaction order, the pre-exponential coefficient can be calculated from the reaction rate corresponding to any pressure-temperature equivalence ratio. This gives us all the reaction rate constants.

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

[0129] It is understandable that before step 220 , the combustion parameters of the combustion chamber need to be acquired. The combustion parameters include the flow rate and temperature of the oxygen-enriched gas, and the flow rate and temperature of the oxygen-enriched gas.

[0130] The calculation process of pure mixed gas temperature is:

[0131] Using the formula:

[0132]

[0133] Perform weighted calculation to obtain the pure mixed gas temperature; where T mix is the pure mixed gas temperature, Q1 is the oxygen-rich gas flow rate, Q2 is the fuel-rich gas flow rate, T1 is the temperature of the oxygen-rich gas, and T2 is the temperature of the fuel-rich gas.

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

[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 mixed gas temperature, and the thrust chamber throat area in the full-flow regenerative cycle engine; ignoring the equivalence ratio in the first quantitative relationship, and determining a third quantitative relationship based on the first quantitative relationship and the second quantitative relationship; the third quantitative relationship is a quantitative relationship of ignition delay with respect to the total gas flow rate and the pure mixed gas temperature; and determining the third quantitative relationship as the auto-ignition index.

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

[0137]

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

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

[0140]

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

[0142] Since the equivalence ratio does not change much, the effect of the equivalence ratio on the ignition delay can be ignored, that is, let A constant (e.g. ), then formula (3) becomes:

[0143]

[0144] P 室 Replace P in formula (5) and T mix Substituting T in formula (5), the third quantitative relationship formula (6) is obtained after transformation of formula (5):

[0145] (6)

[0147] In this way, the ignition delay τ is established with respect to the total gas flow Q total and pure mixed gas temperature T mix A quantitative relationship is established, and the quantitative relationship is defined as a self-ignition index. For example, the third quantitative relationship is defined as a self-ignition index.

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

[0149] Step 300 may specifically include:

[0150] 1) Using formula (6), i.e., the third quantitative relationship, calculate the auto-ignition index values ​​under different operating conditions (operating parameters);

[0151] The self-ignition index is a key indicator of ignition speed. Formula (6) shows that the self-ignition index is a function of 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 ​​serve as the basis for subsequent analysis and judgment. Only by first obtaining the self-ignition index under different operating conditions can we further determine the ignition difficulty and ignition limit.

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

[0153] The larger the self-ignition index value, the faster and easier ignition is under that operating condition; conversely, the slower and more difficult it is. This ranking provides an intuitive understanding of the difficulty of ignition under different operating conditions, providing a preliminary reference and classification basis for subsequent determination of ignition limits, and helping to quickly screen the possible ignition limit range from a wide range of operating conditions.

[0154] 3) Determine the self-ignition limit critical value based on the target self-ignition limit operating range and the sorted self-ignition index set. For example, when the self-ignition index is greater than this value, ignition is possible; when it is less than this value, ignition is not possible. Then, determine the self-ignition limit based on the self-ignition limit critical value.

[0155] Based on the auto-ignition index ranking obtained in the previous steps and combined with the results of three-dimensional calculations of the auto-ignition process of the liquid oxygen-methane full-flow staged combustion cycle engine, the ignition limit value is determined. Three-dimensional calculations can more realistically simulate the actual conditions within the engine. By comparing the auto-ignition index under different operating conditions with the results of the three-dimensional calculations indicating whether ignition is possible, a critical auto-ignition index value is identified. When the auto-ignition index is greater than this value, the three-dimensional calculation indicates that the engine can ignite; when it is less than this value, it cannot ignite. This critical value is the preliminarily determined auto-ignition limit, which is the key node connecting the auto-ignition index and the actual ignition situation.

[0156] Understandably, given the relatively crude nature of zero-dimensional analysis, the self-ignition limit may not be a strictly fixed value, but rather a range within which ignition or failure may occur. Above this range, ignition is guaranteed; below this range, ignition is definitely impossible. Based on the self-ignition limit (a value or a range), it is possible to determine whether ignition is possible under certain operating conditions and determine the maximum throttling depth for ignition constraints.

[0157] For example: Assume that ten working conditions are calculated, each working condition is calculated by the pure mixing temperature T mix , total flow Q total The corresponding ignition delays (τ1, τ2, ..., τ10) are calculated and ranked from smallest to largest for different operating conditions (τ1 < τ2 < ... < τ10). If, while matching the target self-ignition limit operating range, it is found that τ1 to τ4 can self-ignite, but τ5 to τ10 cannot, the self-ignition limit is determined to be within the τ4 to τ5 range. If the ignition delay for a given operating condition is less than τ4, it can self-ignite, but greater than τ5, it cannot.

[0158] In the second specific embodiment, combined with Figure 4 The method for estimating the autoignition limit of a full-flow staged combustion cycle engine is described.

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

[0160] Determine whether self-ignition can be achieved; if so, mark the operating condition as ignition-capable; if not, mark the operating condition as ignition-incapable;

[0161] Mark the working condition according to the judgment result, shrink the ignition boundary range, and obtain the ignition boundary marked by the three-dimensional result;

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

[0163] Establishing the first quantitative relationship of ignition delay with respect to pressure, temperature and equivalence ratio;

[0164] Constructing a second quantitative relationship between chamber pressure and pure mixed gas temperature and total gas flow rate;

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

[0166] Sort the ignition difficulty of each working condition according to the self-ignition index;

[0167] Combining the self-ignition index with the ignition boundary marked by the three-dimensional results, the self-ignition limit is obtained;

[0168] Based on the self-ignition limit, determine whether the working conditions can achieve self-ignition.

[0169] The self-ignition limit estimation device for a full-flow regenerative combustion cycle engine provided by the present invention is described below. The self-ignition limit estimation device for a full-flow regenerative combustion cycle engine described below and the self-ignition limit estimation method for a full-flow regenerative combustion cycle engine described above can be referenced to each other.

[0170] like Figure 5 As shown, an embodiment of the present invention further provides a device for estimating the self-ignition limit of a full-flow regenerative combustion cycle engine, which is used to implement the method for estimating the self-ignition limit of a full-flow regenerative combustion cycle engine in any of the above embodiments. The device for estimating the self-ignition limit of a full-flow regenerative combustion cycle engine may include:

[0171] A simulation calculation module 510 is used to perform a three-dimensional numerical simulation of the auto-ignition process of the full-flow secondary combustion cycle engine to obtain a target auto-ignition limit operating condition range;

[0172] A first determination module 520 is configured to construct a self-ignition index based on the ignition delay data, the pure mixed gas temperature, and the total gas flow rate;

[0173] The second determination module 530 is configured to match the auto-ignition index with the target auto-ignition limit operating condition range to determine the auto-ignition limit.

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

[0175] Acquire a first operating condition combination set; the operating condition factors in each operating condition combination in the first operating condition combination set include at least liquid oxygen flow rate and methane flow rate;

[0176] Constructing a three-dimensional numerical calculation model according to the calculation domain of the full-flow secondary combustion cycle engine;

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

[0178] Analyzing the first temperature field output data to determine whether each operating condition combination achieves self-ignition, thereby obtaining a first determination result;

[0179] determining a first self-ignition limit operating condition range based on the first judgment result;

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

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

[0182] Selecting a second operating condition combination set from the first self-ignition limit operating condition range;

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

[0184] Analyzing the second temperature field output data to determine whether each operating condition combination achieves self-ignition, thereby obtaining a second determination result;

[0185] determining a second self-ignition limit operating condition range based on the second judgment result;

[0186] If the second self-ignition limit operating condition range is within a preset operating condition range, determining the second self-ignition limit operating condition range 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 operating condition range combination set and perform three-dimensional numerical simulation calculations until the new operating condition range combination set is within the preset operating condition range.

[0188] The second determining module 530 is specifically configured to:

[0189] Based on the ignition delay data, a first quantitative relationship is constructed; the first quantitative relationship is a quantitative relationship of the ignition delay with respect to pressure, temperature, and equivalence ratio;

[0190] The auto-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 configured to:

[0192] Determining the reaction rate constant using the Arrhenius equation based on the ignition delay data;

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

[0194] The second determining module 530 is specifically configured to:

[0195] Constructing a second quantitative relationship, wherein the second quantitative relationship is a quantitative relationship between the chamber pressure of the thrust chamber in the full-flow staged combustion cycle engine and the total flow rate of the fuel gas, the temperature of the pure mixed fuel gas, and the throat area of ​​the thrust chamber;

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

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

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

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

[0200] Using the formula:

[0201]

[0202] Perform weighted calculation to obtain the pure mixed gas temperature; wherein, T mix is the pure mixed gas temperature, Q1 is the oxygen-rich gas flow rate, Q2 is the fuel-rich gas flow rate, T1 is the oxygen-rich gas temperature, and T2 is the fuel-rich gas temperature.

[0203] The calculation process of ignition delay data is:

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

[0205] The maximum value of the temperature change rate over time is used as the judgment basis for ignition delay, and different operating parameters are calculated using a zero-dimensional isobaric adiabatic combustion model 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 that characterizes the relationship between the ignition delay and multiple operating parameters.

[0206] The second determining module 530 is specifically configured to:

[0207] Matching the auto-ignition index with the auto-ignition limit operating range to obtain at least one auto-ignition critical index value;

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

[0209] An embodiment of the present invention further 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 executable by the processor; when the processor executes the computer program, it can execute the auto-ignition limit estimation method for a full-flow staged combustion cycle engine described in any of the above embodiments.

[0210] In addition, the logical instructions in the above-mentioned memory can be implemented in the form of a software functional unit and can be stored in a computer-readable storage medium when sold or used as an independent product. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory, a random access memory, a magnetic disk or an optical disk.

[0211] In yet another aspect, the present invention further provides a non-transitory computer-readable storage medium having instructions stored therein. When the instructions are executed, the method for estimating the auto-ignition limit of a full-flow regenerative cycle engine in any of the above embodiments is implemented.

[0212] Although the present invention has been described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by reviewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in the claims. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0213] Although the present invention has been described with reference to specific features and embodiments thereof, it will be apparent that various modifications and combinations may be made thereto without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention as defined by the appended claims and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the invention. It will be apparent that various modifications and variations may be made to the present invention by those skilled in the art without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such modifications and variations as fall within the scope of the claims of the present invention and their equivalents.

Claims

1. A method for estimating the autoignition limit of a full-flow secondary combustion cycle engine, characterized in that: include: Conduct three-dimensional numerical simulation of the auto-ignition process of a full-flow staged combustion cycle engine to determine the target auto-ignition limit operating range; Construct the auto-ignition index based on the ignition delay data, pure mixed gas temperature and total gas flow rate; The self-ignition index is matched with the target self-ignition limit operating range to obtain the self-ignition limit.

2. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 1, characterized in that: The three-dimensional numerical simulation of the auto-ignition process of the full-flow secondary combustion cycle engine is performed to obtain the target auto-ignition limit operating condition range, including: Acquire a first operating condition combination set; the operating condition factors in each operating condition combination in the first operating condition combination set include at least liquid oxygen flow rate and methane flow rate; Constructing a three-dimensional numerical calculation model according to the calculation domain of the full-flow secondary combustion cycle engine; Based on the first operating condition combination set, the three-dimensional numerical calculation model is used to perform a three-dimensional numerical simulation calculation on the full-flow regenerative cycle engine under each operating condition combination to obtain first temperature field output data under each operating condition; Analyzing the first temperature field output data to determine whether each operating condition combination achieves self-ignition, thereby obtaining a first determination result; determining a first self-ignition limit operating condition range based on the first judgment result; Based on the first self-ignition limit operating condition range, a target self-ignition limit operating condition range is determined.

3. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 2, characterized in that: The determining of a target self-ignition limit operating condition range based on the first self-ignition limit operating condition range includes: Selecting a second operating condition combination set from the first self-ignition limit operating condition range; Based on the second operating condition combination set, the three-dimensional numerical calculation model is used to perform a three-dimensional numerical simulation calculation on the full-flow regenerative cycle engine under each operating condition combination to obtain second temperature field output data under each operating condition; Analyzing the second temperature field output data to determine whether each operating condition combination achieves self-ignition, thereby obtaining a second determination result; determining a second self-ignition limit operating condition range based on the second judgment result; If the second self-ignition limit operating condition range is within a preset operating condition range, determining the second self-ignition limit operating condition range 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 operating condition range combination set and perform three-dimensional numerical simulation calculations until the new operating condition range combination set is within the preset operating condition range.

4. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 1, characterized in that: The self-ignition index is constructed based on the ignition delay data, the pure mixed gas temperature and the total gas flow, including: Based on the ignition delay data, a first quantitative relationship is constructed; the first quantitative relationship is a quantitative relationship of the ignition delay with respect to pressure, temperature, and equivalence ratio; The auto-ignition index is determined based on the pure mixed gas temperature, the total gas flow rate, and the first quantitative relationship.

5. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 4, characterized in that: The constructing a first quantitative relationship based on the ignition delay data includes: Determining the reaction rate constant using the Arrhenius equation based on the ignition delay data; The first quantitative relationship is determined based on the ignition delay data and the reaction rate constant.

6. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 4, characterized in that: The determining the auto-ignition index based on the pure mixed gas temperature, the total gas flow rate, and the first quantitative relationship includes: Constructing a second quantitative relationship, wherein the second quantitative relationship is a quantitative relationship between the chamber pressure of the thrust chamber in the full-flow staged combustion cycle engine and the total flow rate of the fuel gas, the temperature of the pure mixed fuel gas, and the throat area of ​​the thrust chamber; Ignoring the equivalence ratio in the first quantitative relationship, and determining a third quantitative relationship based on the first quantitative relationship and the second quantitative relationship; the third quantitative relationship is a quantitative relationship between the ignition delay, the total gas flow rate, and the pure mixed gas temperature; The third quantitative relationship is determined as the auto-ignition index.

7. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 1, characterized in that: The total gas flow is the sum of the oxygen-rich gas flow and the fuel-rich gas flow; The calculation process of the pure mixed gas temperature is: Using the formula: Perform weighted calculation to obtain the pure mixed gas temperature; wherein, T mix is the pure mixed gas temperature, Q1 is the oxygen-rich gas flow rate, Q2 is the fuel-rich gas flow rate, T1 is the oxygen-rich gas temperature, and T2 is the fuel-rich gas temperature.

8. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 1, characterized in that: The calculation process of ignition delay data is: Construct a zero-dimensional isobaric adiabatic combustion model; The maximum value of the temperature change rate over time is used as the judgment basis for ignition delay, and different operating parameters are calculated using a zero-dimensional isobaric adiabatic combustion model 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 that characterizes the relationship between the ignition delay and multiple operating parameters.

9. The method for estimating the auto-ignition limit of a full-flow secondary combustion cycle engine according to claim 1, characterized in that: Match the self-ignition index with the self-ignition limit operating range to determine the self-ignition limit, including: Matching the auto-ignition index with the auto-ignition limit operating range to obtain at least one auto-ignition critical index value; The at least one auto-ignition critical index value is determined as the auto-ignition limit.

10. A device for estimating the autoignition limit of a full-flow secondary combustion cycle engine, characterized in that: include: A simulation calculation module is used to perform three-dimensional numerical simulation of the auto-ignition process of the full-flow secondary combustion cycle engine to obtain the target auto-ignition limit operating condition range; A first determination module is used to construct a self-ignition index based on the ignition delay data, the pure mixed gas temperature and the total gas flow rate; The second determination module is used to match the self-ignition index with the target self-ignition limit operating condition range to determine the self-ignition limit.

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