Method for evaluating dynamic and steady state characteristics of main fuel system of aero-engine

Abstract

The invention discloses a dynamic and steady state characteristic evaluation method for a main fuel oil system of an aero-engine, which is used for carrying out systematic evaluation on dynamic and steady state performance of the main fuel oil system in different design stages. Respectively establishing differential evaluation mechanisms of three stages of design scheme demonstration, principle prototype development and product shaping and batch production; multi-dimensional evaluation of system response characteristics, control performance and robustness is realized by constructing a nonlinear system model and a linearized frequency domain model and combining typical working condition simulation and a principle prototype test; in the batch production stage, a standardized input working condition and a simplified index system are adopted, and batch production prototype performance consistency analysis and rapid quality judgment are achieved. According to the method, systematic evaluation of the aero-engine main fuel system in the full design stage can be achieved, a comprehensive evaluation system combining a model and a test is constructed, the design efficiency and reliability are improved, and the evaluation precision and credibility are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of aircraft engine fuel system design and control, and relates to the design and evaluation of fuel systems, in particular to a method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system. Background Art

[0002] The aircraft engine main fuel system is a core subsystem of the aircraft engine control system. Its dynamic and steady-state characteristics directly affect the engine's thrust response, combustion stability, and overall performance. It is a crucial component of the closed-loop control function within the engine control system. As advanced aircraft engines develop toward higher thrust-to-weight ratios, wider operating envelopes, and more complex control strategies, increasingly stringent requirements are placed on the main fuel system's dynamic response and steady-state accuracy.

[0003] The bandwidth of the main fuel control loop in most traditional engine control systems is 0 to 2 Hz (or approximately 10 rad / s). Traditional control here refers to all modern and historically established turbine engine control systems, while non-traditional control refers to control methods such as rapid response control, active stability control, and tip clearance control, which are still in the research or development stage. The engine's dynamic characteristics within the 0-2 Hz bandwidth are called dominant dynamics. For example, the American F100 engine has five dominant dynamics. The exact location of these extremes varies depending on the specific engine, as the size and construction of the engine's components determine the rates of change of pressure and temperature within each component and cavity. The number of dominant dynamics (or state variables) for various turbine engine models generally ranges from 3 to 5, reflecting the inter-coupling characteristics of multiple physical quantities within the system, such as pressure, flow, and temperature.

[0004] The key to control system design and evaluation is identifying the frequency spectrum of interest for a closed-loop system. The key to selecting the correct frequency spectrum during forward design and evaluation lies in understanding the system's dynamic characteristics. The frequency spectrum of interest is the range within which a closed-loop control system should exhibit satisfactory performance despite disturbances and uncertainties. This spectrum is a function of the actuators and control laws of the system's dynamic control system. The designed control law should ensure satisfactory system performance both in steady-state and dynamic conditions. For example, the frequency spectrum of the American F100 engine ranges from 0.5 to 500 rad / s (or 0.08 to 80 Hz). From a control system design perspective, this represents a wide frequency spectrum, encompassing multiple levels of requirements, from basic control bands to active control bands. Furthermore, the maximum frequency is 1000 times the minimum frequency, or three orders of magnitude higher. This wide frequency spectrum presents challenges for control system design, as different sensor and actuator technologies may be required to control different dynamic characteristics at different frequency levels.

[0005] The product design and evaluation system of aircraft engine fuel systems is one of the core technologies of forward design of aircraft engine fuel systems. Existing evaluation methods mainly use time domain and frequency domain methods. Although these two methods can reflect the performance of fuel systems to a certain extent, they still have many shortcomings in actual application: First, the evaluation process is not coherent, and there is a lack of a complete evaluation chain from the initial design to the final design; second, the evaluation content is single, and differentiated evaluation content is not set for different design stages; third, the evaluation indicators are not comprehensive, and it is difficult to fully reflect the dynamic and steady-state response capabilities of the system under complex working conditions; fourth, the evaluation method is simple and fails to effectively integrate multi-dimensional means such as theoretical modeling, frequency domain analysis and physical test verification.

[0006] In summary, the lack of a systematic dynamic and steady-state performance evaluation method for aircraft engine main fuel systems during the multi-stage design process makes it difficult to effectively map the system's dynamic characteristics to control objectives. Therefore, establishing a dynamic and steady-state performance evaluation mechanism for main fuel systems that targets the dominant dynamic spectrum, integrates frequency-domain and time-domain indicators, and covers the multi-stage design process of the fuel system has become a pressing technical challenge in the forward design and control matching of aircraft engine fuel systems. Summary of the Invention

[0007] (1) Purpose of the invention

[0008] In response to the problems of simple design processes and evaluation content, single methods and indicators for aircraft engine fuel system products, the present invention aims to propose a method for simply, comprehensively and effectively evaluating the design indicators and performance of aircraft engine fuel systems. This method clarifies the evaluation content, evaluation indicators and processes of fuel system products at different stages according to different product design stages and aircraft engine application scenarios, and uses this method to evaluate whether the system design is reasonable. This method has the advantages of more efficient and accurate evaluation of the dynamic and steady-state characteristics of the main fuel system of an aircraft engine, and plays a guiding role in the forward design, component selection and system evaluation of the main fuel system of the gear pump oil supply architecture.

[0009] (2) Technical solution

[0010] In order to achieve the purpose of the invention and solve the technical problems, the present invention adopts the following technical solutions:

[0011] A method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system is used to systematically evaluate the dynamic and steady-state performance of the main fuel system of an aircraft engine gear pump fuel supply architecture at different design stages to assist in system forward design, structure selection, and control matching. The method includes at least the following steps during implementation:

[0012] S100. Identify and determine evaluation objectives during the design phase:

[0013] According to the forward design process of the main fuel system, the system design stage is identified, including three stages: design scheme demonstration, prototype development, and product finalization and mass production. Corresponding dynamic and steady-state performance evaluation targets are determined for different stages, and differentiated evaluation processes are formulated. The design scheme demonstration stage focuses on the feasibility of the system architecture and the matching of basic dynamic and steady-state performance. The prototype development stage focuses on the consistency of system performance optimization and simulation verification. The product finalization and mass production stage focuses on the consistency verification and evaluation of system performance.

[0014] S200. Modeling and performance evaluation during the design scheme demonstration phase:

[0015] A nonlinear model is established based on the preselected main fuel system architecture. Simulation analysis is performed in conjunction with typical engine operating conditions to obtain the system's dynamic and steady-state performance parameters. The nonlinear model is then linearized based on the steady-state operating point, and a linear state-space or transfer function model is established. Time-domain and frequency-domain analysis is then performed based on this model. Finally, based on the obtained dynamic and steady-state performance parameters and time-frequency performance parameters, a determination is made as to whether the preselected system architecture meets the target control performance requirements. If not, adjustments are made to the system architecture until a fuel system architecture that meets the performance requirements is determined.

[0016] S300. Model optimization and verification in the prototype design phase:

[0017] Based on the determined fuel system architecture, the nonlinear model parameters and control laws are optimized, and simulation calculations are performed accordingly to obtain the optimized dynamic and steady-state performance parameters. Simultaneously, the linear model is optimized based on the nonlinear model, and the optimized time-frequency characteristics are obtained through time-domain and frequency-domain analysis. Simultaneously, prototype tests are conducted to verify and compare the simulation and time-frequency analysis results. If the deviation of key indicators exceeds the preset threshold, the model is modified until the model results meet the design indicator requirements.

[0018] S400. Dynamic and steady-state performance evaluation of products in the finalized batch production stage:

[0019] Based on the final design scheme formed in the principle prototype stage, standardized input conditions and modular test methods are used to test the system dynamic and steady-state performance of the mass-produced prototype. Representative time-frequency domain performance indicators are selected to construct a simplified evaluation system to evaluate the system batch consistency and performance stability. If systematic deviations are found in typical indicators, they need to be traced back to the design or manufacturing links for closed-loop correction to ensure that the system batch production has stable and reliable dynamic and steady-state control performance.

[0020] (3) Technical effects

[0021] Compared with the prior art, the method for evaluating the dynamic and steady-state characteristics of the main fuel system of an aircraft engine of the present invention has the following beneficial and significant technical effects:

[0022] (1) The present invention establishes a staged dynamic and steady-state performance evaluation framework for the main fuel system, covering the entire process of design scheme demonstration, prototype development and product finalization and mass production. According to the modeling accuracy requirements and control performance targets of different design stages, the evaluation strategy and indicator system are dynamically adjusted to achieve closed-loop iterative optimization from nonlinear modeling, linearization analysis, control law tuning to experimental verification, effectively improving the scientificity, systematicity and engineering practicality of the system forward design.

[0023] (2) The present invention combines nonlinear model simulation with linear model analysis, systematically integrating time-domain and frequency-domain evaluation indicators to construct a complete analysis framework for the dynamic and steady-state characteristics of the fuel system. Through closed-loop iterative optimization of model simulation and experimental verification, not only can the dynamic and steady-state characteristics of the system be accurately predicted and evaluated, but standardized test conditions and modular test methods are also formed, greatly improving the consistency evaluation efficiency of batch prototypes. In particular, within the system spectrum bandwidth range of 0 to 10 Hz, this method can effectively evaluate and optimize the frequency response characteristics of the system, ensuring that the fuel system has stable and reliable control performance within the full operating range of the engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Flowchart of the method for evaluating the dynamic and steady-state characteristics of the main fuel system;

[0025] Figure 2 This is a schematic diagram of step response index requirements;

[0026] Figure 3 This is a schematic diagram of the slope response index requirements;

[0027] Figure 4 This is the closed-loop control principle block diagram of a fuel control engine;

[0028] Figure 5 Provide a block diagram of the main fuel metering system for the gear pump fuel supply architecture;

[0029] Figure 6 Provide a flow chart for the evaluation of fuel system design solutions during the demonstration phase;

[0030] Figure 7 Design a time domain and frequency domain evaluation flow chart for the fuel system;

[0031] Figure 8 Evaluate the flow chart for the fuel system prototype design phase. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the implementation of the present invention clearer, the technical solutions in the embodiments of the present invention will be described in more detail below with reference to the drawings in the embodiments of the present invention. The described embodiments are part of the embodiments of the present invention, not all of the embodiments, and the described embodiments are exemplary and are intended to be used to explain the present invention, but should not be understood as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] As a specific embodiment, the method for evaluating the dynamic and steady-state characteristics of the main fuel system of an aircraft engine of the present invention can be a method for simply, comprehensively and effectively evaluating the design indicators and performance of the fuel system of an aircraft engine. The method clarifies the evaluation content, evaluation indicators and processes of the fuel system product at different stages according to the different design stages of the product and the application scenarios of the aircraft engine. The method is used to evaluate whether the system design is reasonable. The method has the advantages of more efficient and accurate evaluation of the dynamic and steady-state characteristics of the main fuel system of an aircraft engine, and plays a guiding role in the forward design, component selection and system evaluation of the main fuel metering system.

[0034] Specifically, if Figure 1 As shown, the method includes the following steps when implemented:

[0035] S100. Identify and determine evaluation objectives during the design phase:

[0036] According to the forward design process of the main fuel system, the design stage of the system is identified, including three stages: design scheme demonstration, prototype development and product finalization and mass production. Corresponding dynamic and steady-state performance evaluation targets are determined for different stages and differentiated evaluation processes are formulated. Among them, the design scheme demonstration stage focuses on the matching of system architecture feasibility and basic dynamic and steady-state performance; the prototype development stage focuses on the consistency of system performance optimization and simulation verification; the product finalization and mass production stage focuses on the consistency verification and evaluation of system performance.

[0037] Preferably, when identifying the design stage of the system, an initial review and classification of the system input and output structure, functional module integration method and / or control mode is conducted, and combined with the differences in system architecture openness, performance maturity and / or model completeness at different design stages, a mapping logical relationship between the design stage and the evaluation requirements is established to support subsequent differentiated model construction, indicator definition and verification method selection. In addition, when determining the corresponding dynamic and steady-state performance evaluation targets for different stages, the time domain indicator group and frequency domain indicator group that need to be evaluated first at each stage are determined based on the development tasks of the system stage, the complexity of the control requirements, the bandwidth range of the control law and / or the coverage of typical working conditions, and a phased target matrix is ​​constructed to guide the focus of subsequent model construction and test verification.

[0038] Furthermore, when designing the main fuel system, the embodiment of the present invention first determines the spectrum that deserves attention in the control system design. The dynamics of the system within this spectrum are the most important and are related to whether the closed-loop system performance requirements can be met. The dynamics within this spectrum are the dominant dynamics of the required control system. The engine dynamics are divided into three spectra that deserve attention: 1) basic control bandwidth 0-10Hz; 2) extreme protection control bandwidth, 10-200Hz; 3) active control bandwidth, above 200Hz or even more than 1000Hz. Therefore, the spectrum bandwidth of the aircraft engine fuel system design is generally within the range of 0-10Hz. The design of the aircraft engine fuel system is generally evaluated using time domain and frequency domain methods. The parameters involved in the step response index are defined according to Figure 2 As shown in the figure, the definition of tracking error in the slope response index is as follows: Figure 3 shown.

[0039] Figure 2 and Figure 3 In the delay time t d It is defined as the time required from the step response to the feedback reaching 10% of the final value, that is, t d =A+(BA)×10%; rise time t r : For a system with vibration, it is defined as the time required for the value to rise from zero (A) to the final value (B) for the first time; for a system without overshoot, it is defined as the time required for the value to rise from 10% (A+(B-A)×10%) to 90% (A+(B-A)×90%) of the final value; adjustment time t s It is defined as the time required for the step response to reach and remain within ±5% of the final value (B±(BA)×10%). The dynamic error ζ% is defined as the absolute value of the difference between the dynamic and fixed state feedback value and the given value. The overshoot σ% is defined as (CB) / (BA)×100%.

[0040] When designing the main fuel system, follow the design requirements and indicators. If no specific design technical requirements are put forward, the turbine engine can refer to the following indicators for preliminary design and evaluation: The time domain design of the main fuel metering system meets t d (delay time)+t r (Rise time) ≤ 0.2s; Adjustment time t s≤1.2s; overshoot σ% ≤2%; dynamic error ζ% ≤2%. The frequency domain design of the main fuel metering system meets the requirements of a magnitude margin (GM) greater than 10dB; a phase margin (PM) greater than 45°; and a bandwidth (BW) greater than 1.2rad / s. GM is defined as the difference between the phase and -180° when the system's open-loop transfer function amplitude is 1, reflecting the system's ability to withstand gain changes. Phase margin PM is defined as the difference between the amplitude and 1 when the system's open-loop transfer function phase is -180°, reflecting the system's ability to withstand phase changes. BW is defined as the frequency at which the system's frequency response drops to -3dB, reflecting the system's response speed.

[0041] More specifically, the dynamic and steady-state performance evaluation targets of each stage include at least the following three categories: (1) System steady-state performance targets, which are used to measure the regulation accuracy and energy efficiency performance of the fuel system during the steady-state control process, including at least the fuel flow control accuracy (steady-state error is not greater than the preset tolerance), fuel supply pressure stability (residual fluctuation amplitude after the disturbance is eliminated) and / or system static energy consumption (driving energy required per unit flow output); (2) System dynamic performance targets, which are used to evaluate the transient characteristics and dynamic quality of the fuel system when responding to control commands or external disturbances, including at least the delay time t d , rise time t r , adjustment time t s , overshoot σ%, dynamic error ζ%, amplitude margin GM, phase margin PM, and / or bandwidth BW. Each indicator can be extracted and evaluated jointly through nonlinear simulation results and linear model frequency response; (3) system robustness objectives, which at least include the ability of the fuel system to maintain stable performance under changes in component characteristics (such as actuator response time, valve opening-flow characteristic drift), external disturbances (such as load steps) and / or changes in environmental conditions (such as temperature, pressure).

[0042] The three types of indicator targets have different weight division principles in different design stages: the design scheme demonstration stage focuses on the system dynamic performance targets (verifying the system structure's rapid response capability to control inputs and the dominant dynamic matching), the prototype development stage balances the three types of targets (aims to verify the prediction consistency and comprehensive performance of the simulation model), and the product finalization and batch production stage focuses on the system steady-state performance and robustness targets (ensuring system quality stability and safety of use during mass production).

[0043] S200. Modeling and performance evaluation during the design scheme demonstration phase:

[0044] A nonlinear model is established based on the preliminarily selected main fuel system architecture, and simulation analysis is performed in combination with typical engine operating conditions to obtain the system's dynamic and steady-state performance parameters. The system's nonlinear model is then linearized based on the steady-state operating point, and a linear state space or transfer function linear model is established, upon which time and frequency domain analysis is performed. Finally, based on the obtained dynamic and steady-state performance parameters and time-frequency performance parameters, it is determined whether the preliminarily selected system architecture can meet the target control performance requirements. If not, the system architecture is adjusted until a fuel system architecture that meets the performance requirements is determined.

[0045] In the embodiment of the present invention, according to the application scenario of the aircraft engine and the working principle of the aircraft engine control system, the current aircraft engine main fuel control system mainly includes two closed-loop controls, namely a position feedback closed loop and a state feedback closed loop (such as Figure 4 As shown in the figure, the primary fuel system architecture is a gear pump fuel supply architecture, which is a closed-loop system consisting of a fuel metering system and an LVDT sensor (i.e., a position feedback sensor). It includes control laws, electro-hydraulic servo valves, main fuel metering valves, differential pressure valves, constant pressure valves, locking valves, return valves, boost valves, gear fuel pumps, and LVDT components. The architecture is shown in the figure. Figure 5 As shown, the position feedback closed loop is composed of the electro-hydraulic servo valve, the main fuel metering valve and the position feedback sensor, which is used to achieve precise control of the fuel flow rate. The state feedback closed loop is composed of the pressure differential valve, the constant pressure valve and related pipelines, which is used to maintain stable working conditions of the system.

[0046] Furthermore, in the design solution demonstration stage, the indicators to be evaluated in the time domain analysis include at least the delay time t d , rise time t r , adjustment time t s , overshoot σ% and / or dynamic error ζ%; the indicators to be evaluated in frequency domain analysis include at least amplitude margin GM, phase margin PM, and / or bandwidth BW; the target control performance requirements include: within the system spectrum bandwidth range (0-10Hz), the delay time t d With rise time t r The sum is no more than 0.2 seconds, and the adjustment time t s No more than 1.2 seconds, overshoot σ% no more than 2%, dynamic error ζ% no more than 2%, amplitude margin GM greater than 10dB, phase margin PM greater than 45°, bandwidth BW greater than 1.2rad / s.

[0047] More specifically, the embodiment of the present invention includes at least the following sub-steps when implementing the modeling and performance evaluation of the design solution demonstration stage in step S200: Figure 6 As shown:

[0048] S201. System Nonlinear Model Construction: Based on the preselected main fuel system architecture and combined with system principle decomposition, a multi-physics coupled nonlinear dynamic model of the fuel system is established through numerical simulation or mathematical derivation. Boundary conditions and interface variables of key system components are defined to ensure that the system model is physically interpretable and simulatable.

[0049] S202. System Dynamic Simulation and Parameter Acquisition: Based on the constructed system nonlinear model, simulation calculations are performed under typical engine operating conditions, including at least acceleration from ground slow to maximum state, acceleration from high-altitude slow to maximum state, and deceleration from maximum state to ground slow. The system dynamic response curve and steady-state error data are obtained.

[0050] S203. System Linearization: Linearize and simplify the nonlinear model near the system's typical steady-state operating point to obtain a linear state-space linear model or transfer function linear model that reflects the system's small-signal response characteristics. Use system identification to verify the accuracy of the resulting linear model.

[0051] S205. Time domain and frequency domain performance analysis: Perform time domain and frequency domain analysis based on the constructed linear model. Calculate various time domain indicators based on the response of the linear model under step input, including at least the delay time t d , rise time t r , adjustment time t s , overshoot σ% and dynamic error ζ%, and analyze and calculate the amplitude margin GM, phase margin PM and bandwidth BW of the system in the frequency domain through linear model;

[0052] S206. Comprehensive judgment of evaluation results: Based on the obtained dynamic and steady-state and time-frequency characteristic parameters, by comparing them with the preset evaluation criteria, a comprehensive judgment is made as to whether the preliminarily selected system architecture can meet the target control performance requirements. If so, the current system architecture is confirmed; if not, the system architecture is adjusted and optimized, and steps S201 to S205 are repeated until an overall design solution that meets the performance requirements is obtained.

[0053] Furthermore, the embodiment of the present invention includes at least the following sub-steps when performing time domain and frequency domain evaluation of fuel system design: Figure 7 As shown:

[0054] S211. Fuel System Nonlinear Modeling: Based on the preselected main fuel system architecture, a mathematical model of the fuel system is constructed using two parallel modeling methods. For situations requiring in-depth analysis of system mechanisms, nonlinear formula derivation based on the system dynamics equations is used to develop the model. For situations requiring rapid construction of complex system models, component-based modeling based on numerical simulation (e.g., AMESim commercial software) is employed to ensure the model accurately reflects the system's physical characteristics and dynamic behavior.

[0055] S212. System Linearization: For nonlinear formula models, linearization is performed near the selected system rated operating point using methods such as Taylor expansion to obtain a state-space model describing the system's small-signal characteristics. Based on the numerical simulation modeling results, linearization is performed at the same operating point and simplified and reduced using methods such as modal truncation to form a linear model.

[0056] S213. Linear Model Comparison and Verification: Compare and analyze the linear models obtained from the two approaches to verify the consistency of their frequency response characteristics. Quantify the model differences by calculating metrics such as root mean square error to ensure sufficient accuracy and reliability of the linear models.

[0057] S214. Control Structure and Parameter Selection: Based on the verified linear model, select an appropriate small closed-loop control structure and its key parameters. For example, for the position feedback closed-loop, use an LVDT sensor as the feedback element combined with a PID control law to adjust the main fuel metering valve opening. For the state feedback closed-loop, introduce the differential pressure valve pressure signal as feedforward compensation to improve oscillation suppression in the critical protection frequency band (10-200 Hz). Initial control parameter values ​​are adjusted based on the boundary conditions of an amplitude margin >10 dB and a phase margin >45°. This lays the foundation for subsequent open-loop and closed-loop system characteristic analysis.

[0058] S215. Open-Loop Transfer Function Analysis: Calculate the system's open-loop transfer function and analyze it in the frequency domain. Draw the Nyquist curve and Bode plot, focusing on evaluating the system's frequency-domain characteristics, including amplitude margin (≥10dB) and phase margin (≥45°), to ensure sufficient system stability margin.

[0059] S216. Closed-Loop Transfer Function Analysis: Calculate the system's closed-loop transfer function and perform dual verification in the frequency and time domains. In the frequency domain, focus on analyzing the system's bandwidth (BW ≥ 1.2 rad / s). In the time domain, focus on testing key indicators such as response time (the sum of delay time and rise time ≤ 0.2 seconds), overshoot (σ% ≤ 2%), and steady-state error (ζ% ≤ 2%).

[0060] S217. Record and analyze the evaluation results: Record and compare the time domain and frequency domain evaluation results to evaluate whether the system meets the preset performance index requirements. If not, adjust the control structure parameters or return to step S211 to re-model and optimize the system until the system performance meets the requirements;

[0061] S218. Sensitivity Analysis and Robustness Evaluation: Parameter sensitivity analysis is conducted to assess the system's sensitivity to changes in key parameters, while ensuring that performance requirements are met. Robustness evaluation is also conducted using Monte Carlo methods to ensure that the system maintains stable dynamic and steady-state performance despite parameter fluctuations.

[0062] S300. Model optimization and verification in the prototype design phase:

[0063] Based on the determined fuel system architecture, the nonlinear model parameters and control laws are optimized, and simulation calculations are performed accordingly to obtain the optimized dynamic and steady-state performance parameters. At the same time, the linear model is optimized based on the nonlinear model, and the optimized time-frequency characteristics are obtained through time domain and frequency domain analysis. Simultaneously, principle prototype tests are carried out to verify and compare the simulation and time-frequency analysis results. If the deviation of key indicators exceeds the preset threshold, the model is corrected until the model results meet the design indicator requirements.

[0064] More specifically, the embodiment of the present invention includes at least the following sub-steps when implementing the model optimization and verification in the prototype design stage of step S300: Figure 8 As shown:

[0065] S301. Nonlinear Model Parameter Optimization: Based on the fuel system architecture and control method determined during the design solution demonstration phase, parameter identification and structural optimization are performed on the existing nonlinear model. Incorporating the measured physical characteristics of the prototype, the nonlinear response characteristics and coupling relationships of each component are corrected. The control law is then tuned and optimized to improve the accuracy and stability of the model during dynamic response.

[0066] S302. Optimized nonlinear model simulation: Use the optimized nonlinear model to simulate the system's dynamic and steady-state performance, obtaining the system's dynamic and steady-state performance parameters under typical operating conditions, with a focus on the system's consistent performance across the entire operating range.

[0067] S303. System Linear Model Reconstruction and Time-Frequency Analysis: Based on the optimized nonlinear model, linearization is performed at multiple typical operating points. Time and frequency domain analysis is performed on each linear model to obtain the optimized fuel system's time and frequency domain performance parameters at different operating points.

[0068] S304. Principle prototype test verification: Organize and carry out principle prototype system-level tests, including at least typical step disturbance response tests, ramp input tests, and frequency sweep tests. Collect the system response data under different working conditions and compare them with the model simulation and time-frequency analysis results. Calculate the deviation values ​​of key indicators. If the deviation results exceed the preset threshold, perform parameter correction and structural optimization on the nonlinear model based on the test data until the deviation between the model prediction results and the test data meets the accuracy requirements.

[0069] S400. Dynamic and steady-state performance evaluation of products in the finalized batch production stage:

[0070] Based on the final design scheme formed in the principle prototype stage, standardized input conditions and modular test methods are used to test the system dynamic and steady-state performance of the mass-produced prototype. Representative time-frequency domain performance indicators are selected to construct a simplified evaluation system to evaluate the system batch consistency and performance stability. If systematic deviations are found in typical indicators, they need to be traced back to the design or manufacturing links for closed-loop correction to ensure that the system batch production has stable and reliable dynamic and steady-state control performance.

[0071] Preferably, the modular test method includes system-level test bench verification and component-level response comparison testing, and a comprehensive evaluation of system performance is achieved through a hierarchical testing strategy; standardized input conditions include step, ramp and disturbance inputs, etc. The step input condition is used to simulate the response of the fuel system when the engine accelerates or decelerates rapidly, the ramp input condition is used to simulate the situation where the fuel flow demand changes slowly and continuously, and the disturbance input condition is used to simulate the impact of external environmental disturbances or sudden changes in downstream oil load on the system.

[0072] Furthermore, the performance evaluation in the product finalization and batch production stage follows the principles of simplicity and practicality. Based on the complete dynamic and steady-state indicator system extracted in the early design scheme demonstration stage and the principle prototype development stage, through indicator sensitivity analysis and statistical correlation analysis methods, representative time-frequency domain performance indicators are selected to construct a simplified evaluation system while ensuring that the key performance of the system can be reflected.

[0073] In summary, the method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system provided by the embodiment of the present invention constructs a dynamic and steady-state evaluation system for the entire process, from scheme demonstration and prototype development to batch production verification. It achieves the goals of quantifiable performance, traceable structure, and closed-loop verification of the main fuel system during the design phase, and has significant engineering practical value and promotion prospects.

[0074] The above embodiments fully and effectively achieve the objectives of the present invention. Those skilled in the art will appreciate that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the above specific embodiments. Although the present invention has been described with reference to the embodiments currently considered to be the most practical and preferred, it should be understood that the present invention is not limited to the disclosed embodiments, and any modifications that do not deviate from the functional and structural principles of the present invention are intended to be included within the scope of the claims.

Claims

1. A method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system, characterized in that: The method comprises at least the following steps when implemented: S100. Design stage identification and evaluation target determination: Based on the main fuel system forward design process, identify the system's current design stage, including design solution demonstration, prototype development, and product finalization and mass production. Determine the corresponding dynamic and steady-state performance evaluation targets for each stage. S200. Modeling and performance evaluation during the design demonstration phase: Build a nonlinear model based on the preselected main fuel system architecture, conduct simulation analysis based on typical engine operating conditions, and obtain system dynamic and steady-state performance parameters. Based on the steady-state operating point, the nonlinear model is linearized, a linear model is established, and time-domain and frequency-domain analysis is performed accordingly. Based on the obtained dynamic and steady-state performance parameters, it is determined whether the preselected system architecture can meet the target control performance requirements, and the fuel system architecture is ultimately selected. S300. Model Optimization and Verification during the Prototype Design Phase: Based on the determined fuel system architecture, nonlinear model parameters and control laws are optimized. Simulations are then performed to obtain optimized dynamic and steady-state performance parameters. Linear model optimization is also performed, and optimized time-frequency characteristics are obtained through time-domain and frequency-domain analysis. Prototype tests are conducted, and simulation and time-frequency analysis results are verified and compared. If deviations from key indicators exceed preset thresholds, the model is revised until the results meet design requirements. S400. Dynamic and steady-state performance evaluation of product finalization and batch production: Standardized input conditions and modular test methods are used to test the system's dynamic and steady-state performance of batch production prototypes. Representative time-frequency domain performance indicators are selected to construct a simplified evaluation system to assess the system's batch production consistency and performance stability.

2. The method for evaluating the dynamic and steady-state characteristics of the main fuel system of an aircraft engine according to claim 1, characterized in that: In step S100, when identifying the design stage of the system, an initial review and classification of the system input and output structure, functional module integration method and / or control mode is performed, and combined with the differences in system architecture openness, performance maturity and / or model completeness of different design stages, a mapping logical relationship between the design stage and the evaluation requirements is established.

3. The method for evaluating the dynamic and steady-state characteristics of the main fuel system of an aircraft engine according to claim 1, characterized in that: In step S100, when determining the corresponding dynamic and steady-state performance evaluation targets for different stages, the time domain indicator group and frequency domain indicator group that need to be evaluated first in each stage are determined based on the development tasks, control requirement complexity, control law bandwidth range and / or typical operating condition coverage of the system stage, and a stage-by-stage target matrix is ​​constructed to guide the subsequent model construction and test verification focus.

4. The method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system according to any one of claims 1 to 3, characterized in that: In step S100, the dynamic and steady-state performance evaluation targets include at least: (1) system steady-state performance targets, including at least fuel flow control accuracy, fuel supply pressure stability and / or system static energy consumption; (2) system dynamic performance targets, including at least delay time t d , rise time t r , adjustment time t s , overshoot σ%, dynamic error ζ%, amplitude margin GM, phase margin PM, and / or bandwidth BW; (3) system robustness objectives, including at least the ability of the fuel system to maintain stable performance under changes in component characteristics, external disturbances and / or changes in environmental conditions.

5. The method for evaluating the dynamic and steady-state characteristics of the main fuel system of an aircraft engine according to claim 1, characterized in that: In step S200, during the design scheme demonstration stage, the primary fuel system architecture is preliminarily selected as a gear pump fuel supply architecture, which at least includes a control law, an electro-hydraulic servo valve, a main fuel metering valve, a pressure differential valve, a constant pressure valve, a locking valve, an oil return valve, a boost valve, a gear fuel pump, and a position feedback sensor; the gear pump fuel supply architecture includes at least two closed-loop control loops, namely, position feedback and state feedback, wherein the position feedback closed loop is composed of the electro-hydraulic servo valve, the main fuel metering valve, and the position feedback sensor, and the state feedback closed loop is composed of the pressure differential valve, the constant pressure valve, and related pipelines; the system's spectral bandwidth ranges from 0 to 10 Hz, covering the main frequency components that the system needs to respond to during engine acceleration and deceleration.

6. The method for evaluating the dynamic and steady-state characteristics of the main fuel system of an aircraft engine according to claim 5, characterized in that: In step S200, during the design solution demonstration phase, the indicators to be evaluated in the time domain analysis include at least the delay time t d , rise time t r , adjustment time t s , overshoot σ% and / or dynamic error ζ%; The indicators to be evaluated in frequency domain analysis include at least amplitude margin GM, phase margin PM, and / or bandwidth BW; The target control performance requirements include: within the system spectrum bandwidth, the delay time t d With rise time t r The sum is no more than 0.2 seconds, and the adjustment time t s No more than 1.2 seconds, overshoot σ% no more than 2%, dynamic error ζ% no more than 2%, amplitude margin GM greater than 10dB, phase margin PM greater than 45°, bandwidth BW greater than 1.2rad / s.

7. The method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system according to claim 1, 5 or 6, characterized in that: In step S200, when implementing the modeling and performance evaluation in the design solution demonstration phase, at least the following sub-steps are included: S201. System Nonlinear Model Construction: Based on the preselected main fuel system architecture and combined with system principle decomposition, a multi-physics coupled nonlinear dynamic model of the fuel system is established; S202. System Dynamic Simulation and Parameter Acquisition: Based on the constructed system nonlinear model, simulation calculations are performed under typical engine operating conditions to obtain the system dynamic response curve and steady-state error data; S203. System Linearization: Linearize the nonlinear model near a typical steady-state operating point to obtain a linear state space or transfer function linear model that reflects the system's small-signal response characteristics. S205. Time-Domain and Frequency-Domain Performance Analysis: Perform time-domain and frequency-domain analysis based on the system's linear model. Calculate the system's time-domain performance based on the linear model's response to a step input. Also, calculate the system's frequency-domain performance using the linear model in the frequency domain. S206. Comprehensive judgment of evaluation results: Based on the obtained dynamic and steady-state performance parameters and time-frequency characteristic parameters, by comparing them with the preset evaluation criteria, a comprehensive judgment is made as to whether the pre-selected system architecture can meet the target control performance requirements. If not, the system architecture is adjusted and optimized.

8. The method for evaluating the dynamic and steady-state characteristics of the main fuel system of an aircraft engine according to claim 7, characterized in that: In step S200, the time domain and frequency domain evaluation includes at least the following sub-steps: S211. Fuel System Nonlinear Modeling: Based on the preselected main fuel system architecture, a mathematical model of the fuel system is constructed using a parallel modeling approach consisting of nonlinear formula derivation and numerical simulation to ensure that the model accurately reflects the physical characteristics and dynamic behavior of the system. S212. System Linearization: For nonlinear formula models, perform linearization derivation near the selected system rated operating point to obtain a state-space model describing the system's small-signal characteristics. Based on the numerical simulation modeling results, perform linearization and simplification and order reduction at the same operating point to form a linear model. S213. Linear Model Comparison and Verification: Compare and analyze the linear models obtained from the two approaches to verify the consistency of their frequency response characteristics and ensure that the linear models have sufficient accuracy and reliability. S214. Control Structure and Parameter Selection: Based on the verified linear model, select an appropriate small closed-loop control structure and its key parameters, laying the foundation for subsequent open-loop and closed-loop characteristic analysis of the system. S215. Open-Loop Transfer Function Analysis: Calculate the system's open-loop transfer function and analyze it in the frequency domain, focusing on evaluating the system's frequency-domain characteristics to ensure adequate system stability margin. S216. Closed-Loop Transfer Function Analysis: Calculate the closed-loop transfer function of the system and verify it in both the frequency and time domains. Focus on analyzing the system bandwidth frequency in the frequency domain, and focus on testing the response time, overshoot and steady-state error indicators in the time domain; S217. Record and analyze the evaluation results: Record and analyze the time domain and frequency domain evaluation results to evaluate whether the system meets the preset performance index requirements. If not, adjust the control structure parameters or return to step S211 to re-model and optimize the system until the system performance meets the requirements; S218. Sensitivity Analysis and Robustness Evaluation: Conduct parameter sensitivity analysis based on performance requirements to assess the system's sensitivity to changes in key parameters. Perform robustness evaluation based on the Monte Carlo method to ensure that the system maintains stable dynamic and steady-state performance despite parameter fluctuations.

9. The method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system according to claim 1, characterized in that: In step S300, model optimization and verification in the prototype design phase at least includes: S301. Nonlinear Model Parameter Optimization: Based on the established fuel system architecture and control method, perform parameter identification and structural optimization on the existing nonlinear model. Combined with the measured physical characteristics of the prototype, the nonlinear response characteristics and coupling relationships of each component are corrected, and the control law is tuned and optimized. S302. Optimized nonlinear model simulation: Use the optimized nonlinear model to simulate the system's dynamic and steady-state performance, obtaining the system's dynamic and steady-state performance parameters under typical operating conditions, with a focus on the system's consistent performance across the entire operating range. S303. System Linear Model Reconstruction and Time-Frequency Analysis: Based on the optimized nonlinear model, linearization is performed at multiple typical operating points. Time and frequency domain analysis is performed on each linear model to obtain the optimized fuel system's time and frequency domain performance parameters at different operating points. S304. Principle prototype test verification: Organize and carry out principle prototype system-level tests, including at least step disturbance response, ramp input and frequency sweep tests, collect response data under different working conditions, and compare them with model simulation and time-frequency analysis results, calculate the deviation value of key indicators, and if the deviation result exceeds the preset threshold, perform parameter correction and structural optimization on the nonlinear model based on the test data.

10. The method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system according to claim 1, wherein: In step S400, the modular test method includes system-level test bench verification and component-level response comparison testing, and a comprehensive evaluation of system performance is achieved through a hierarchical testing strategy; the standardized input conditions include at least step, ramp and disturbance input conditions, among which the step input condition is used to simulate the response of the fuel system when the engine accelerates or decelerates rapidly, the ramp input condition is used to simulate the situation where the fuel flow demand changes slowly and continuously, and the disturbance input condition is used to simulate the impact of external environmental disturbances or sudden changes in downstream oil load on the system.

11. The method for evaluating the dynamic and steady-state characteristics of an aircraft engine main fuel system according to claim 1, characterized in that: In step S400, the performance evaluation of the product in the finalization and batch production stage follows the principles of simplicity and practicality. Based on the complete dynamic and steady-state indicator system extracted in the early design scheme demonstration stage and the principle prototype development stage, representative time-frequency domain performance indicators are selected through indicator sensitivity analysis and statistical correlation analysis methods to construct a simplified evaluation system.

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