Consideration of the overall safety analysis method of multi-domain physical coupling of aviation piston engine

Abstract

The application belongs to the technical field of safety analysis of aviation piston engines, and specifically discloses a whole safety analysis method considering multi-domain physical coupling of aviation piston engines, comprising: establishing multiple physical domain degrees for work data division and collection; obtaining work data of the engine, and creating an analysis model for each physical domain degree; obtaining the correlation of work parameters between the analysis models, and composing a multi-domain physical model; inputting the crank angle data of the engine into the multi-domain physical model to obtain random variables, and obtaining safety results by sampling based on the distribution of the random variables and the safety boundary of the engine work parameters; and having the following advantages: the interaction between different domain degrees is coupled to form a whole multi-domain physical model, thereby avoiding the limitations when facing complex coupling problems; subjectivity and ambiguity caused by qualitative description in traditional safety analysis are avoided, the safety analysis of aviation piston engines is more objective and accurate, and the dependence on experience is reduced.

Description

Technical Field

[0001] This invention relates to the field of safety analysis technology for aero-piston engines, and more specifically, to a holistic safety analysis method that considers the multi-domain physical coupling of aero-piston engines. Background Technology

[0002] General aviation is a crucial foundation for the development of civil aviation, forming the "two wings" of civil aviation alongside public transport aviation, and is one of the important guarantees for achieving a strong civil aviation nation. Among general aviation aircraft, piston engines, due to their superior economy, operational flexibility, and easier maintenance, account for the vast majority of power plants and are projected to rise to over 60%. Improving the safety level of piston engines, reducing the absolute number of accidents, and safeguarding public interests in the face of surging general aviation transport volumes are issues that must be addressed for the future development of general aviation.

[0003] Aero-engine piston systems are highly nonlinear systems, and the complexity of their failures lies in the hysteresis and positive feedback response characteristics of the thermal, aerodynamic, and mechanical connections between their components: 1) Hysteresis response characteristics refer to the inability of thermal connections, aerodynamic connections such as the turbocharger and intake / exhaust systems, and mechanical connections such as the piston, cylinder, crankshaft, and connecting rod to respond simultaneously or reach stability when engine operating conditions change instantaneously; 2) Positive feedback response characteristics refer to the fact that when the engine is under low load, the lower exhaust gas energy leads to insufficient turbocharger work capacity, further exacerbating the deterioration of engine intake conditions, causing unstable combustion in the cylinder, and even engine shutdown; conversely, when the engine is under high load, the higher exhaust gas energy causes the turbocharger to work harder and rotate faster, further increasing intake pressure, causing distortion or fluctuations in the in-cylinder combustion environment, which can easily lead to engine runaway or knocking. Therefore, the various physical domains of an aero-engine exhibit strong coupling during operation, resulting in mutually coupled failure modes.

[0004] Traditional safety analysis primarily relies on post-event investigations and analyses, failing to incorporate safety requirements as pre-emptive constraints on the research object or analyze from a system-level perspective. It often requires modifications only after safety issues are exposed during system use and operation. Furthermore, traditional safety analysis methods cannot handle the "dynamic closed-loop event" problem in complex systems. They struggle to decompose and identify primary failure modes, capture the mapping relationship between failures or failure combinations and their consequences, and predict the impact and consequences of failures. Consequently, they cannot accurately and effectively formulate and implement safety control strategies during operation and maintenance. Model-based holistic safety analysis methods can overcome the limitations of traditional methods, beginning in the early stages of system development and demonstration, aiming to prevent unsafe conditions during future operation as much as possible during the design phase. However, they still lack research experience when dealing with complex, multi-domain physical coupling problems such as aero-engine piston engines.

[0005] Therefore, a holistic safety analysis method considering the multi-domain physical coupling of aero-piston engines is proposed to address the aforementioned problems. Summary of the Invention

[0006] The present invention aims to provide an overall safety analysis method that considers the multi-domain physical coupling of aero piston engines, in order to solve or improve the problem of coupling failure in complex systems mentioned above, which is difficult to decompose and identify the mode of primary failure, and difficult to analyze and capture the failure or the mapping relationship between failure components and consequences from the perspective of the whole machine.

[0007] In view of this, a first aspect of the present invention is to provide an overall safety analysis method that takes into account the multi-domain physical coupling of an aero-piston engine.

[0008] The first aspect of the present invention provides a method for overall safety analysis considering multi-domain physical coupling of an aero-piston engine, comprising the following steps: S1, establishing multiple physical domains for dividing and collecting working data based on the physical properties of the engine's operating parameters; S2, starting and acquiring the engine's operating data, shutting down the engine, and creating an analysis model for each physical domain according to the parameter coupling of the operating parameters; S3, acquiring the data interaction control of the operating parameters between the analysis models, and combining all analysis models into a multi-domain physical model to characterize the engine's operating process; S4, inputting the engine's crankshaft angle data into the multi-domain physical model to obtain the variation law of all operating parameters with the crankshaft angle; S5, determining whether the variation law is qualified; if qualified, proceeding to S6; if unqualified, deleting the analysis model and the multi-domain physical model, and then returning to S2; S6, acquiring random variables of the engine during operation through the multi-domain physical model, and obtaining safety results for evaluating the overall safety of the engine by sampling based on the distribution of the random variables and the engine safety boundaries corresponding to the operating parameters.

[0009] Specifically, to determine whether a change pattern is qualified, the result obtained based on this pattern is compared with the experimental results to judge whether it is qualified.

[0010] Furthermore, the physical domain includes: thermodynamic domain, fluid dynamics domain, and mechanical dynamics domain; the operating parameters of the thermodynamic domain include: scavenging timing, scavenging quality, in-cylinder pressure, and in-cylinder temperature; the operating parameters of the fluid dynamics domain include: airflow velocity, airflow field, pressure fluctuation, mixing rate, and combustion heat release law; the operating parameters of the mechanical dynamics domain include: piston displacement, piston velocity, and piston acceleration.

[0011] Furthermore, the parameter coupling includes: the changes in in-cylinder pressure, in-cylinder temperature, and scavenging timing coupling to affect changes in scavenging quality; the changes in pressure fluctuations and mixing rate coupling to affect changes in combustion heat release patterns, airflow field, and airflow velocity; and the changes in piston acceleration coupling to affect piston velocity and piston displacement. The data interaction control includes: the combustion heat release patterns, intake quality, piston displacement, and scavenging timing interactively controlling in-cylinder pressure and in-cylinder temperature; the in-cylinder pressure and in-cylinder temperature interactively controlling scavenging quality and combustion heat release patterns; the piston velocity interactively controlling airflow velocity, combustion heat release patterns, in-cylinder pressure, and in-cylinder temperature; and the airflow field interactively controlling piston acceleration, piston velocity, and airflow velocity.

[0012] Furthermore, the analysis model includes: a thermodynamic analysis model, a fluid dynamics analysis model, and a mechanical dynamics analysis model; the thermodynamic analysis model is as follows: In the formula, , , , T For temperature, For crankshaft rotation angle, For mechanical work, For heat exchanged through the system boundary, For quality Energy brought into or out of the system For the quality of the working fluid, u For the working fluid specific internal energy, p For working fluid pressure, For excess air coefficient, R For gas constant, For volume, j For the counting terms when summing, The enthalpy value; the fluid dynamics analysis model: In the formula, For the pressure in the intake / exhaust system, For the volume of the intake / exhaust system, For the mass of the intake / exhaust system, For the temperature in the intake / exhaust system, For the specific internal energy in the intake / exhaust system, Energy brought into the fluid system For system wall heat dissipation, For the quality flowing out of the system, Energy carried by a unit mass flowing out For the quality of the incoming system, For crankshaft rotation angle, , Energy per unit mass working fluid quality N The number of cylinders connected to the system; the mechanical dynamics analysis model: In the formula, For piston motion acceleration, crank radius, For crankshaft rotational angular velocity, For crank angle, , and These are the inertial force of the piston, the force exerted by the connecting rod on the piston, and the lateral force exerted by the piston on the cylinder. For engine torque, The force is the gas force, and α is the angle between the force and the perpendicular direction.

[0013] Furthermore, the determination of the change pattern adopts the following rules: In the formula, For the characteristic function, when The value is 1 if it is true, and 0 otherwise. w The safety boundary corresponding to the operating parameters. g s The changes in the working parameters output by the multi-domain physical model.

[0014] Furthermore, the engine safety boundary is defined as follows: the output of the engine's operating parameters under normal conditions is taken as the center line, and ±5% is extended as the safety boundary.

[0015] Furthermore, all the analytical models in step S3 constitute a multi-domain physical model for characterizing the engine's operating process, specifically through the following steps: Step 1, input the geometric parameters, thermodynamic parameters, and flow parameters of the aero-piston engine; Step 2, obtain the compressor and turbine characteristic curves, and the intake and exhaust valve cam lift curves, as essential conditions for model input; Step 3, for the compressor operating parameters, including the compressor inlet pressure P... K and temperature T K And the compression start point parameters during engine operation, including pressure P. Z Mass at the starting point of compression m z Compression start point inlet pressure P B and temperature T B First, initial values ​​are given, and the process begins iterative looping. Second, the starting point for each operating parameter's change over time is set as the compression initiation point. Then, based on the analysis model, the system of differential equations is integrated within one working cycle of the engine, and the pressure P before the compression initiation point is calculated. B and temperature T B Step 5: Determine the inlet pressure P K and temperature T KIf convergence has occurred, proceed to step six; otherwise, return to step four. Step six: Determine the compressor operating parameter P. K T K If convergence has occurred, return to step four and correct P. K If so, proceed to step seven; step seven, calculate the comprehensive performance parameters of the engine, including the engine's effective power; step eight, complete the calculation of the aviation piston engine in this cycle, use the engine's effective power change curve with the crankshaft angle as a multi-domain physical model and output the results; step nine, determine whether it is the final operating condition, if so, end the calculation, otherwise return to step four.

[0016] The beneficial effects of this invention compared to the prior art are as follows:

[0017] Starting from the safety requirements and physical domain connotation of aero-piston engines, we first establish multiple physical domain models, then form a multi-domain physical model of the whole engine by exploring the interaction and coupling between different domains, and obtain the overall engine safety through probabilistic quantitative analysis using Monte Carlo simulation, thereby avoiding the limitations of traditional safety analysis methods when facing complex coupled problems.

[0018] Based on the data interaction mechanism between physical models of different domains, parameters with transmission relationships will occur between different disciplines. The transmission relationship between them is the data interaction mechanism, which enables the joint rather than isolated safety analysis of physical models of different domains, thereby laying the foundation for considering the overall safety analysis of the entire aircraft piston engine.

[0019] By employing the Monte Carlo simulation method to characterize the safety impact from a quantitative probabilistic perspective, the subjectivity and ambiguity brought about by the qualitative description in traditional safety analysis can be avoided, thus making the safety analysis of aero-piston engines more objective and accurate, and reducing reliance on experience.

[0020] Additional aspects and advantages of embodiments of the invention will become apparent in the following description or may be learned by practice of embodiments of the invention. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0022] Figure 1 This is a flowchart of the present invention;

[0023] Figure 2 This is a simplified diagram of the multi-physics domain coupling relationship of the aero-piston engine of the present invention;

[0024] Figure 3This is a flowchart illustrating the construction process of the multi-domain physical model of the entire aero-piston engine of the present invention.

[0025] Figure 4 This is a flowchart illustrating the simulated security process of the present invention;

[0026] Figure 5 This is a graph showing the in-cylinder temperature variation as the crankshaft angle changes according to the present invention.

[0027] Figure 6 Design a standardized safety distribution histogram for the existing technology before improvement;

[0028] Figure 7 This is a standardized safety distribution histogram after the design improvement of this invention. Detailed Implementation

[0029] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0030] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0031] Please see Figure 1-4 The following describes an overall safety analysis method for aero-engine piston engines that considers multi-domain physical coupling, based on some embodiments of the present invention.

[0032] The first aspect of this invention proposes a holistic safety analysis method considering multi-domain physical coupling in aero-engine piston engines. In some embodiments of this invention, such as... Figure 1-4 As shown, a holistic safety analysis method considering multi-domain physical coupling of aero-piston engines is provided. This holistic safety analysis method considering multi-domain physical coupling of aero-piston engines includes:

[0033] S1, based on the physical properties of the engine's operating parameters, establish multiple physical domains for dividing and collecting operating data;

[0034] S2, start and acquire engine operating data, shut down the engine, and create an analysis model for each physical domain degree based on the parameter coupling of the operating parameters;

[0035] S3, acquire the data interaction control of the working parameters between the analysis models, and combine all the analysis models into a multi-domain physical model to characterize the engine working process;

[0036] S4 inputs the engine crankshaft angle data into the multi-domain physical model to obtain the variation law of all working parameters with crankshaft angle;

[0037] S5, determine whether the change pattern is qualified. If qualified, proceed to S6. If not qualified, delete the analysis model and multi-domain physical model, and then return to S2.

[0038] S6 obtains the random variables of the engine during operation through a multi-domain physical model. Based on the distribution of the random variables and the engine safety boundary corresponding to the operating parameters, sampling is used to obtain safety results for evaluating the overall safety of the engine.

[0039] The present invention provides an overall safety analysis method for aero-piston engines that considers multi-domain physical coupling. Starting from the safety requirements and physical domain connotations of aero-piston engines, it first establishes multiple physical domain models, then forms a whole-engine multi-domain physical model by mining the interaction and coupling between different domains, and obtains the overall engine safety probabilistically and quantitatively through Monte Carlo simulation, thereby avoiding the limitations of traditional safety analysis methods when facing complex coupled problems.

[0040] Based on the data interaction mechanism between physical models of different domains, parameters with transmission relationships will occur between different disciplines. The transmission relationship between them is the data interaction mechanism, which enables the joint rather than isolated safety analysis of physical models of different domains, thereby laying the foundation for considering the overall safety analysis of the entire aircraft piston engine.

[0041] By employing the Monte Carlo simulation method to characterize the safety impact from a quantitative probabilistic perspective, the subjectivity and ambiguity brought about by the qualitative description in traditional safety analysis can be avoided, thus making the safety analysis of aero-piston engines more objective and accurate, and reducing reliance on experience.

[0042] In any of the above embodiments, the physical domain includes: thermodynamic domain, fluid dynamics domain, and mechanodynamics domain;

[0043] The operating parameters of thermodynamic domain include: scavenging timing, scavenging quality, in-cylinder pressure, and in-cylinder temperature;

[0044] The working parameters of the fluid dynamics domain include: airflow velocity, airflow field, pressure fluctuation, mixing rate, and combustion heat release.

[0045] The operating parameters of the mechanical dynamics domain include: piston displacement, piston velocity, and piston acceleration.

[0046] In this embodiment, by considering the above-mentioned operating parameters, it is possible to analyze the overall security of the machine from different physical domain perspectives.

[0047] In any of the above embodiments, the parameter coupling includes: the changes in in-cylinder pressure, in-cylinder temperature and scavenging timing coupled to affect the changes in scavenging quality; the changes in pressure fluctuation and mixing rate coupled to affect the combustion heat release law, airflow field and airflow velocity; and the changes in piston acceleration coupled to affect piston velocity and piston displacement.

[0048] Data-driven interactive control includes: interactive control of combustion heat release law, intake air quality, piston displacement and scavenging timing to control in-cylinder pressure and in-cylinder temperature; interactive control of in-cylinder pressure and in-cylinder temperature to control scavenging quality and combustion heat release law; interactive control of piston movement speed to control airflow speed, combustion heat release law, in-cylinder pressure and in-cylinder temperature; and interactive control of airflow field to control piston acceleration, piston speed and airflow speed.

[0049] In this embodiment, by directly considering the coupling between parameters in the model, different physical domains can be integrated into the overall security analysis. This avoids the need for traditional security analysis methods to manually decompose the entire system into subsystems for analysis when performing overall security analysis, which makes it difficult to consider the interaction between different systems and different physical domains.

[0050] In any of the above embodiments, the analysis model includes: a thermodynamic analysis model, a fluid dynamics analysis model, and a mechanical dynamics analysis model;

[0051] The thermodynamic analysis model is as follows:

[0052] ;

[0053] In the formula, , , , T For temperature, For crankshaft rotation angle, For mechanical work, For heat exchanged through the system boundary, For quality Energy brought into or out of the system For the quality of the working fluid, u For the working fluid specific internal energy, p For working fluid pressure, For excess air coefficient, R For gas constant, For volume, j For the counting terms when summing, Enthalpy value;

[0054] Fluid dynamics analysis model:

[0055] ;

[0056] In the formula, For the pressure in the intake / exhaust system, For the volume of the intake / exhaust system, For the mass of the intake / exhaust system, For the temperature in the intake / exhaust system, For the specific internal energy in the intake / exhaust system, Energy brought into the fluid system For system wall heat dissipation, For the quality flowing out of the system, Energy carried by a unit mass flowing out For the quality of the incoming system, For crankshaft rotation angle, , Energy per unit mass working fluid quality N The number of cylinders connected to the system;

[0057] Mechanical dynamics analysis model:

[0058] ;

[0059] In the formula, For piston motion acceleration, crank radius, For crankshaft rotational angular velocity, For crank angle, , and These are the inertial force of the piston, the force exerted by the connecting rod on the piston, and the lateral force exerted by the piston on the cylinder. For engine torque, The force is the gas force, and α is the angle between the force and the perpendicular direction.

[0060] In this embodiment, the thermodynamic analysis model can be described from the perspective of engine thermodynamics, thereby simulating temperature changes as the crankshaft angle changes. The fluid dynamics analysis model can be described from the perspective of fluid dynamics, thereby simulating changes in pressure, mass flow rate, and energy of the engine's working gas as the crankshaft angle changes. The mechanical dynamics analysis model can be described from the perspective of mechanical dynamics, thereby simulating the operation and force characteristics of engine mechanical components as the crankshaft angle changes. Furthermore, by constructing a one-dimensional model of each physical domain as the crankshaft angle changes while meeting the requirements of safety analysis, the overly coarse nature of a zero-dimensional model of the entire engine in analyzing problems is avoided, as well as the complexity of a three-dimensional model in computational analysis.

[0061] In any of the above embodiments, the determination of the change pattern adopts the following rules:

[0062] ;

[0063] In the formula, For the characteristic function, when The value is 1 if it is true, and 0 otherwise. w The safety boundary corresponding to the operating parameters. g s The changes in the working parameters output by the multi-domain physical model.

[0064] In this embodiment, the impact of security is quantitatively evaluated through indicator functions, avoiding the ambiguity and vagueness of qualitative descriptions of security. Moreover, it can quantitatively analyze the impact of each random variable on security, i.e., sensitivity analysis.

[0065] In any of the above embodiments, the engine safety boundary is:

[0066] The operating parameters of the engine under normal conditions are used as the center line, and ±5% is extended as the safety boundary.

[0067] In this embodiment, by considering the overall operating parameters of the engine rather than the parameters of a specific subsystem as the safety boundary, a safety analysis can be performed from the perspective of the entire engine.

[0068] In any of the above embodiments, all the analysis models in step S3 constitute a multi-domain physical model for characterizing the engine's working process, specifically in the following steps:

[0069] Step 1: Input the geometric parameters, thermodynamic parameters, and flow parameters of the aircraft piston engine;

[0070] Step 2: Obtain the compressor and turbine characteristic curves, and the intake and exhaust valve cam lift curves, as essential conditions for model input;

[0071] Step 3, regarding the compressor operating parameters, including the compressor inlet pressure P... K and temperature T K And the compression start point parameters during engine operation, including pressure P. Z Mass at the starting point of compression m z Compression start point inlet pressure P B and temperature T B Given an initial value, it enters a loop iteration;

[0072] Step four: The starting point for the change of each working parameter over time is set as the compression start point. Based on the analysis model, the system of integral and differential equations is calculated over one working cycle of the engine, and the pressure P before the compression start point is calculated. B and temperature T B ;

[0073] Step 5, determine the inlet pressure PK and temperature T K Check if convergence has occurred. If yes, proceed to step six; otherwise, return to step four.

[0074] Step 6: Determine the compressor operating parameter P K T K If convergence has occurred, return to step four and correct P. K If so, proceed to step seven;

[0075] Step 7: Calculate the engine's comprehensive performance parameters, including the engine's effective power;

[0076] Step 8: Complete the calculations for the aero-piston engine in this cycle, and use the engine effective power variation curve as a multi-domain physical model to output the results.

[0077] Step 9: Determine if this is the final working condition. If yes, end the calculation; otherwise, return to Step 4.

[0078] In this embodiment, the calculation of some parameters is simplified to meet the requirements of overall system security analysis. Furthermore, the convergence of iterative parameters is judged item by item in the iteration method, which improves the convergence speed of the overall system model calculation compared to the method of judging the convergence of all iterative parameters at the same time.

[0079] Another embodiment of the first aspect of the present invention proposes a method for overall safety analysis considering multi-domain physical coupling of aero-engines, comprising the following steps:

[0080] Step 1: Based on the working principle of aero-piston engines, conduct a parameter and model decoupling theoretical analysis of the entire engine according to safety requirements and physical domain connotations, and determine the physical domain of the analysis as thermodynamics, fluid mechanics, and mechanical dynamics.

[0081] Step 2: Observe and collect data on the thermodynamic analysis domain of the aero-piston engine, simplify the actual complex system into a corresponding physical model, and then give a quantitative mathematical description to the simplified physical model.

[0082] Step 3: Observe and collect data on the hydrodynamic analysis domain of the aero-piston engine, simplify the actual complex system into a corresponding physical model, and then give a quantitative mathematical description to the simplified physical model.

[0083] Step 4: Observe and collect data on the mechanical dynamics analysis domain of the aircraft piston engine, simplify the actual complex system into the corresponding physical model, and then perform a quantitative mathematical description of the simplified physical model.

[0084] Step 5: Based on the established thermodynamic model, fluid dynamics model, and mechanical dynamics model, identify the coupling parameters and data interaction control mechanisms between the models to achieve collaborative interaction between physical models of different domains, and describe the actual working process of the system in the form of differential equations.

[0085] Step 6: Perform simulation calculations using the established preliminary multi-domain physical model to determine the variation law of each parameter of the model with the crankshaft angle, and determine whether it can be verified by experiment; if not, proceed to step 7, otherwise proceed to step 8.

[0086] Step 7: Based on the experimental verification results, correct the model's empirical parameters and return to Step 2.

[0087] Step 8: Based on the verified multi-domain physical model of the aero-piston engine, define the relevant parameters as random variables. Then, based on the defined factor distribution and safety boundary, use the Monte Carlo method to sample the engine model parameters, and finally generate the engine safety results.

[0088] Another embodiment of the first aspect of the present invention proposes a method for overall safety analysis considering multi-domain physical coupling of aero-engines, comprising the following steps:

[0089] Another embodiment of the first aspect of the present invention proposes a holistic safety analysis method considering multi-domain physical coupling of an aero-engine piston engine. For a simplified single-cylinder direct-injection four-stroke piston engine with parameters of bore = 100 mm, stroke = 100 mm, displacement VD = 0.785 L, compression ratio e = 16.50:1, and injection quantity me = 80 mg / cycle, the method includes the following steps:

[0090] The verification results of the whole machine multi-domain physical model established using MATLAB are as follows: Figure 5 As shown, taking the in-cylinder temperature varying with crankshaft angle as an example, a compression ratio failure mode is selected. The variables follow a normal distribution, µ=16.5, σ=1.8. Following the safety calculation method described above, the safety probability under these conditions is 0.9490, meaning that safety decreases by approximately 5.10% when a compression ratio failure occurs. The safety distribution histogram is shown below. Figure 6 As shown. Therefore, to improve the compression ratio failure simulation, σ is reduced to 1.5. A second simulation using the aforementioned safety calculation method yields a safety probability of 0.9778, representing an improvement of approximately 3.03%. The safety distribution histogram is shown below. Figure 7 As shown in the figure. Therefore, the effectiveness of this method is verified both from a data and intuitive perspective.

[0091] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0092] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for overall safety analysis considering multi-domain physical coupling in aero-engines, characterized in that, Includes the following steps: S1, based on the physical properties of the engine's operating parameters, establish multiple physical domains for dividing and collecting operating data; S2, start and acquire engine operating data, shut down the engine, and create an analysis model for each physical domain degree based on the parameter coupling of the operating parameters; S3, acquire the data interaction control of the working parameters between the analysis models, and combine all the analysis models into a multi-domain physical model to characterize the engine working process; S4. Input the engine crankshaft angle data into the multi-domain physical model to obtain the variation law of all working parameters with crankshaft angle; S5, determine whether the change pattern is qualified. If qualified, proceed to S6. If not qualified, delete the analysis model and the multi-domain physical model, and then return to S2. S6. Random variables of the engine during operation are obtained through a multi-domain physical model. Based on the distribution of random variables and the engine safety boundary corresponding to the operating parameters, sampling is used to obtain safety results for evaluating the overall safety of the engine. All the analytical models in step S3 constitute a multi-domain physical model for characterizing the engine's operating process, specifically as follows: Step 1: Input the geometric parameters, thermodynamic parameters, and flow parameters of the aircraft piston engine; Step 2: Obtain the compressor and turbine characteristic curves, and the intake and exhaust valve cam lift curves, as essential conditions for model input; Step 3, regarding the compressor operating parameters, including the compressor inlet pressure P... K and temperature T K And the compression start point parameters during engine operation, including pressure P. Z Mass at the starting point of compression m z Compression start point inlet pressure P B and temperature T B Given an initial value, it enters a loop iteration; Step four: The starting point for the change of each working parameter over time is set as the compression start point. Based on the analysis model, the system of integral and differential equations is calculated over one working cycle of the engine, and the pressure P before the compression start point is calculated. B and temperature T B ; Step 5, determine the inlet pressure P K and temperature T K Check if convergence has occurred. If yes, proceed to step six; otherwise, return to step four. Step 6: Determine the compressor operating parameter P K T K If convergence has occurred, return to step four and correct P. K If so, proceed to step seven; Step 7: Calculate the engine's comprehensive performance parameters, including the engine's effective power; Step 8: Complete the calculations for the aero-piston engine in this cycle, and use the engine effective power variation curve as a multi-domain physical model to output the results. Step 9: Determine if this is the final working condition. If yes, end the calculation; otherwise, return to Step 4.

2. The overall safety analysis method for considering multi-domain physical coupling of aero-piston engines according to claim 1, characterized in that, The physical domain includes: thermodynamic domain, fluid dynamics domain, and mechanodynamics domain; The operating parameters of the thermodynamic domain include: scavenging timing, scavenging quality, in-cylinder pressure, and in-cylinder temperature; The working parameters of the fluid dynamics domain include: airflow velocity, airflow field, pressure fluctuation, mixing rate, and combustion heat release characteristics; The operating parameters of the mechanical dynamics domain include: piston displacement, piston velocity, and piston acceleration.

3. The overall safety analysis method for considering multi-domain physical coupling of aero-piston engines according to claim 2, characterized in that, The parameter coupling includes: the changes in in-cylinder pressure, in-cylinder temperature and scavenging timing coupled to affect the changes in scavenging quality; the changes in pressure fluctuation and mixing rate coupled to affect the combustion heat release law, airflow field and airflow velocity; and the changes in piston acceleration coupled to affect piston velocity and piston displacement. The data interaction control includes: the combustion heat release law, intake air quality, piston displacement and scavenging timing interactively controlling the in-cylinder pressure and in-cylinder temperature; the in-cylinder pressure and in-cylinder temperature interactively controlling the scavenging quality and combustion heat release law; the piston movement speed interactively controlling the airflow movement speed, combustion heat release law, in-cylinder pressure and in-cylinder temperature; and the airflow field interactively controlling the piston movement acceleration, piston movement speed and airflow movement speed.

4. The overall safety analysis method for considering multi-domain physical coupling of aero-piston engines according to claim 2, characterized in that, The analysis models include: thermodynamic analysis model, fluid dynamics analysis model and mechanical dynamics analysis model; The thermodynamic analysis model is as follows: ； In the formula, , , , T For temperature, For crankshaft rotation angle, For mechanical work, For heat exchanged through the system boundary, For quality Energy brought into or out of the system For the quality of the working fluid, u For the working fluid specific internal energy, p For working fluid pressure, For excess air coefficient, R For gas constant, For volume, j For the counting terms when summing, Enthalpy value; The fluid dynamics analysis model: ； In the formula, For the pressure in the intake / exhaust system, For the volume of the intake / exhaust system, For the mass of the intake / exhaust system, For the temperature in the intake / exhaust system, For the specific internal energy in the intake / exhaust system, Energy brought into the fluid system For system wall heat dissipation, For the quality flowing out of the system, Energy carried by a unit mass flowing out For the quality of the water flowing into the system, , Energy per unit mass working fluid quality N The number of cylinders connected to the system; The mechanical dynamics analysis model: ； In the formula, For piston motion acceleration, crank radius, For crankshaft rotational angular velocity, For crank angle, , and These are the inertial force of the piston, the force exerted by the connecting rod on the piston, and the lateral force exerted by the piston on the cylinder. For engine torque, The force is the gas force, and α is the angle between the force and the perpendicular direction.

5. The overall safety analysis method for considering multi-domain physical coupling of aero-piston engines according to claim 1, characterized in that, The following rules are used to determine the pattern of change: ； In the formula, For the characteristic function, when The value is 1 if it is true, and 0 otherwise. w The safety boundary corresponding to the operating parameters. g s The changes in the working parameters output by the multi-domain physical model.

6. The overall safety analysis method for considering multi-domain physical coupling of aero-piston engines according to claim 1, characterized in that, The engine safety boundary is: The operating parameters of the engine under normal conditions are used as the center line, and ±5% is extended as the safety boundary.

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