A Dynamic Modeling Method for Overall Instability of Aero-engines

Abstract

This invention discloses a dynamic modeling method for overall instability of an aero-engine, comprising: (1) constructing a steady-state and transient simulation module for the aero-engine, and calculating the changes in engine performance parameters during the steady-state and transient processes; (2) constructing a dynamic instability simulation module, and calculating the outlet flow rate, outlet pressure, and tip static pressure during the compressor instability process; (3) constructing an actuator control module, and calculating the influence of the jet actuator on the dynamic instability simulation module; and (4) constructing the parameter transfer relationship between the modules. The aero-engine model constructed using this invention can achieve steady-state and dynamic simulation of the entire aero-engine envelope under all operating conditions, while also simulating the changes in various engine parameters during compressor rotational stall and surge states, and can be used for further active stability control simulation research.

Description

Technical Field

[0001] This invention relates to a dynamic modeling method for overall instability of aero-engines, belonging to the field of active stability control of aero-engines. Background Technology

[0002] The core idea of ​​active stability control for aero-engines is to identify any precursory signals indicating partial degradation but still within a safe operating state before instability occurs, using high-performance sensors and advanced signal processing methods. Simultaneously, control methods targeting these precursory signals are implemented to delay or eliminate potential instability disturbances, allowing the engine to operate continuously within its high pressure ratio and high efficiency range. This allows for a smaller margin during the design phase, maximizing blade performance and reducing the overall engine weight and size, while improving safety and fuel economy.

[0003] As extremely complex aero-thermodynamic systems, aero-engine control system design relies heavily on precise mathematical models. Aero-engine mathematical models play an indispensable role in analyzing and designing engine control algorithms, predicting unmeasurable physical quantities within the engine, and in fault diagnosis and fault-tolerant control. Currently, the widely used aero-engine performance simulation models are component-level models. However, due to the high cost and risk of full-engine surge testing, compressor characteristic data across the entire flow range is difficult to obtain. This means that conventional component-level models can only simulate steady-state and transient performance parameters within the surge boundary and cannot simulate unstable dynamic processes such as engine stall and surge. Furthermore, traditional component-level models do not model and study actuators used for stability control, such as the jet propulsion system. Therefore, conventional component-level models cannot be used in aero-engine active stability control research. Authorization number CN112594062B discloses a simulation method for surge detection and surge control verification. It simulates the engine surge ingress and surge regression processes by coupling the MG3 model with the compressor component parameters. However, this invention does not model based on real engine characteristics and can only simulate the pressure and flow changes at the compressor outlet section, and cannot simulate tip pulsation pressure. In addition, this invention does not involve the influence of actuators on engine stability, so it cannot be applied to the research of active stability control and has limitations.

[0004] To conduct model-based research on active stability control of aero-engines, it is necessary to explore the complex coupling mechanism when the compression component works together with the rest of the engine, while also considering the impact of the corresponding actuators on the entire engine. Based on this, a modeling method that can reflect the dynamic characteristics of the aero-engine instability process should be invented. Only then can it be used for further research on stability control strategies, control laws, actuators, and control system design. Summary of the Invention

[0005] The technical problem to be solved by this invention is to overcome the shortcomings of existing aero-engine modeling technology and provide a dynamic modeling method for the overall instability of aero-engines. This method can realize steady-state and dynamic simulation of aero-engines under all operating conditions and envelope, while also simulating the changes of various engine parameters when the compressor is in a rotating stall and surge state, thus providing a model basis for active stability control research.

[0006] The technical solution of this invention:

[0007] A dynamic modeling method for overall instability of an aero-engine, specifically including the following steps:

[0008] Step (1): Construct a steady-state and transient simulation module for aero-engines;

[0009] Step (2): Construct an instability dynamic simulation module;

[0010] Step (3): Construct the actuator control module;

[0011] Step (4) Establish the parameter transfer relationship between each module.

[0012] The step (1) of constructing the steady-state and transient simulation module of the aero-engine specifically involves establishing a component-level model of the aero-engine: first, establishing the aero-thermodynamic model of each sub-component of the engine, and then calculating the changes in performance parameters of the aero-engine during the steady-state and transient processes based on the flow balance equation, static pressure balance equation, power balance equation and rotor dynamics equation between each component.

[0013] Furthermore, the steady-state and transient performance parameters are typical engine performance parameters such as pressure, flow rate, temperature, surge margin, and rotor speed at the inlet / outlet sections of various sub-components of the aero-engine.

[0014] Step (2) of constructing the instability dynamic simulation module specifically includes:

[0015] Step (2.1) extends the compressor characteristic curve cluster of the aero-engine component-level model to the flow region outside the surge boundary;

[0016] Furthermore, the compressor characteristic curve cluster of the aero-engine component-level model is composed of multiple isochronous speed lines of the compressor at different relative speeds n, and each isochronous speed line represents the compressor pressure ratio π when the compressor flow rate is m;

[0017] Furthermore, the compressor characteristic curve extension method involves fitting a family of compressor characteristic curves from an engine component-level model using the following cubic surface equation:

[0018]

[0019]

[0020]

[0021] Where m is the compressor flow rate; π is the compressor pressure ratio; φ is the flow coefficient; ψ is the pressure coefficient; ρ is the gas density inside the compressor; A c ψ(φ, n) is the equivalent cross-sectional area of ​​the internal flow channel of the compressor; U is the linear velocity of the flange at the middle diameter of the compressor rotor; p0 is the ambient pressure; ψ(φ, n) is the compressor characteristic term; n is the compressor speed; a0, a1, b0, b1, c0, c1 are fitting coefficients.

[0022] Step (2.2), based on the extended compressor characteristic surface, establish the compressor instability dynamic model as follows:

[0023]

[0024] Where u is the actuator control quantity input to the model; φ is the flow coefficient output by the model; ψ is the pressure coefficient output by the model; B is the dimensionless B parameter; l c γ is the compressor length; T This refers to the throttle valve opening.

[0025] Step (2.3) uses a third-order Fourier series to fit the test data of the compressor tip static pressure under different surge margins, and establishes the tip static pressure model as follows:

[0026]

[0027] Among them, K i and S i The Fourier coefficients for the fit are derived from linear interpolation of the surge margin. For phase; N c σ is the compressor rotor speed; σ is the model correction coefficient, which is generally taken as 2 to 4.

[0028] Step (3) involves constructing the jet actuator control module, specifically calculating the influence of the jet actuator on the pressure coefficient ψ of the compressor instability dynamic model. j It can be expressed by the following formula:

[0029]

[0030] Among them, A j φ is the nozzle area of ​​the jet actuator. j is the flow coefficient of the jet device, and is the input to the actuator control module.

[0031] Step (4) describes the construction of parameter transfer relationships between modules, including the parameter transfer relationship between the steady-state and transient state simulation module of the aero-engine and the instability dynamic simulation module, and the parameter transfer relationship between the instability dynamic simulation module and the actuator control module;

[0032] Furthermore, the parameter transfer relationship between the aero-engine steady-state and transient state simulation module and the instability dynamic simulation module is as follows:

[0033] The component-level model of the aero-engine will have a rotor speed N c The dynamic model of compressor instability is passed to the compressor instability model. The engine rotor speed is the same as the compressor speed. The compressor instability dynamic model is calculated based on the compressor characteristic term ψ(φ, N) in the calculation model. c );

[0034] The component-level model of the aero-engine will have a rotor speed N c The surge margin SM and the compressor inlet section pressure P2 are transferred to the tip static pressure model to calculate the tip pressure P. tip =P2(C tip +1);

[0035] The compressor instability dynamic model normalizes the output pressure coefficient φ and flow coefficient ψ, and then obtains the pressure influence coefficient C after Savitzky-Golay filtering. ψ and flow influence coefficient C φ Then C ψ C φ Transferred to the engine component-level model;

[0036] After receiving the engine component-level model, the compressor outlet flow rate m3 and compressor outlet pressure P3 are multiplied by the pressure influence coefficient C, respectively. ψ and flow influence coefficient C φ .

[0037] Furthermore, the parameter transfer relationship between the instability dynamic simulation module and the actuator control module is as follows:

[0038] The actuator control module calculates the influence of the pressure coefficient ψ based on the flow coefficient φ from the received compressor instability dynamic model. j This is then passed to the compressor instability dynamic model, i.e., u = ψ j .

[0039] The beneficial effects of this invention are:

[0040] This invention proposes a dynamic modeling method for aero-engine instability, mapping the instability dynamic characteristics of compressor components to the entire aero-engine component-level model. It comprehensively considers the complex coupling relationship between the compressor and other sub-components during operation, solving the problem that traditional aero-engine mathematical models cannot simulate changes in performance parameters such as speed, pressure, and temperature during instability dynamic processes like stall and surge. Simultaneously, it models the influence of the jet actuator on compressor instability dynamics, making the model usable for designing active stability control algorithms. Adopting a modular modeling approach, this invention can extend dynamic instability characteristics based on component-level models of various aero-engines such as turboshaft, turbojet, or turbofan engines, making it suitable for establishing dynamic instability models for various types of aero-engines. Attached Figure Description

[0041] Appendix Figure 1 This is a schematic diagram illustrating the modeling principle of the overall instability dynamic model of a turboshaft engine.

[0042] Appendix Figure 2 It is a cluster of compressor characteristic curves for a component-level model of a turboshaft engine;

[0043] Appendix Figure 3 It is an extended compressor characteristic surface of a turboshaft engine component-level model; Detailed Implementation

[0044] To facilitate public understanding, the technical solution of this invention will be further explained below with reference to the accompanying drawings, using a turboshaft engine as an example.

[0045] Comparison Appendix Figure 1 A dynamic modeling method for instability of aero-engines includes the following steps:

[0046] Step (1) Construct a steady-state and transient simulation module for aero-engines, that is, establish a component-level model of the turboshaft engine to realize the calculation of performance parameters of the steady-state and transient processes of the aero-engine;

[0047] A component-level model of a turboshaft engine is established. Based on the engine's structure and function, aerodynamic and thermodynamic models of the inlet, compressor, combustion chamber, gas turbine, power turbine, exhaust nozzle, and rotor are sequentially established. By solving the common working equations—comprising the flow balance equations at the gas turbine inlet, power turbine inlet, exhaust nozzle throat, compressor and gas turbine power balance, power turbine and rotor power balance, and rotor dynamics—the pressure, flow rate, temperature, surge margin SM, and rotor speed N of each component at the inlet / outlet sections during the steady-state and transient processes of the aero-engine are calculated. c .

[0048] Step (2): Construct an instability dynamic simulation module to calculate the outlet flow coefficient and pressure coefficient during the compressor instability process;

[0049] Step (2.1) extends the compressor characteristic curve cluster of the aero-engine component-level model to the flow region outside the surge boundary; Figure 2 This is a set of compressor characteristic curves for a component-level model of a turboshaft engine, describing the compressor at rotor speed N. c The following describes the distribution of compressor pressure ratio π at a flow rate of m; the following is a set of compressor characteristic curves fitted to the engine component-level model using cubic surface equations:

[0050]

[0051]

[0052]

[0053] Where m is the compressor flow rate; π is the compressor pressure ratio; φ is the flow coefficient; ψ is the pressure coefficient; and ρ is the gas density inside the compressor, taken as 1.225 kg / m³. 3 A c The equivalent cross-sectional area of ​​the internal flow channel of the compressor is taken as 0.0291m. 2 U is the linear velocity of the compressor rotor flange at the mid-diameter, taken as 927.63 m / s; p0 is the ambient pressure, taken as 100 kPa; ψ(φ, n) is the compressor characteristic term; n is the compressor speed; a0, a1, b0, b1, c0, c1 are fitting coefficients.

[0054] The fitted cubic surface in this embodiment is as follows: Figure 3 As shown, specifically:

[0055]

[0056] Step (2.2), based on the extended compressor characteristic surface, establish the compressor instability dynamic model as follows:

[0057]

[0058] Where u is the actuator control input to the model; φ is the flow coefficient of the model output; ψ is the pressure coefficient of the model output; B is the dimensionless B parameter, taken as 1.8; l c Let γ be the equivalent length of the compressor; T The throttle valve opening is set to 0.6.

[0059] Step (2.3) uses a third-order Fourier series to fit the test data of the compressor tip static pressure under different surge margins, and establishes the tip static pressure model as follows:

[0060]

[0061] Among them, K i and S i The Fourier coefficients for the fit are derived from linear interpolation of the surge margin. For phase; N c σ is the compressor rotor speed; σ is the model correction coefficient, which is taken as 2.

[0062] The interpolation table of Fourier coefficients and surge margin for the tip static pressure model is shown in Table 1.

[0063] Table 1. Interpolation table of Fourier coefficients and surge margin

[0064]

[0065]

[0066] Step (3): Construct the actuator control module and calculate the influence of the jet actuator on the pressure coefficient ψ of the compressor instability dynamic model. j as follows:

[0067]

[0068] Among them, A in A represents the compressor inlet area. j Let φ be the nozzle area of ​​the jet actuator. j Here, represents the flow coefficient of the jet device, and represents the input to the actuator control module.

[0069] Step (4) Establish the parameter transfer relationship between each module; including the parameter transfer relationship between the steady-state and transient state simulation module of the aero-engine and the instability dynamic simulation module, and the parameter transfer relationship between the instability dynamic simulation module and the actuator control module.

[0070] Parameter transfer relationship between the steady-state and transient state simulation module and the instability dynamic simulation module of aero-engines:

[0071] The component-level model of the aero-engine will have a rotor speed N c The dynamic model of compressor instability is passed to the compressor instability model. The engine rotor speed is the same as the compressor speed. The compressor instability dynamic model is calculated based on the compressor characteristic term ψ(φ, N) in the calculation model. c );

[0072] The component-level model of the aero-engine will have a rotor speed N c The surge margin SM and the compressor inlet section pressure P2 are transferred to the tip static pressure model to calculate the tip pressure P. tip =P2(C tip +1);

[0073] The compressor instability dynamic model normalizes the output pressure coefficient φ and flow coefficient ψ, and then obtains the pressure influence coefficient C after Savitzky-Golay filtering. ψ and flow influence coefficient C φ Then C ψ C φ Transferred to the engine component-level model;

[0074] After receiving the engine component-level model, the compressor outlet flow rate m3 and compressor outlet pressure P3 are multiplied by the pressure influence coefficient C, respectively. ψ and flow influence coefficient C φ .

[0075] The parameter transfer relationship between the instability dynamic simulation module and the actuator control module is as follows:

[0076] The actuator control module calculates the influence of the pressure coefficient ψ based on the flow coefficient φ from the received compressor instability dynamic model. j This is then passed to the compressor instability dynamic model, i.e., u = ψ j .

[0077] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for dynamic modeling of overall instability of an aero-engine, characterized in that, Includes the following steps: Step (1) Construct a steady-state and transient simulation module for aero-engines, specifically by establishing a component-level model of the aero-engine. First, establish aero-thermodynamic models of each sub-component of the engine, and then calculate the changes in performance parameters of the aero-engine during steady-state and transient processes based on the flow balance equation, static pressure balance equation, power balance equation and rotor dynamics equation between each component. Step (2) involves constructing an instability dynamic simulation module to calculate the outlet flow rate, outlet pressure, and tip static pressure during the compressor instability process. Specifically, this includes: Step (2.1) extends the compressor characteristic curve cluster of the aero-engine component-level model to the flow region outside the surge boundary; specifically, it uses the following cubic surface equation to fit the compressor characteristic curve cluster of the engine component-level model: Where m is the compressor flow rate; π is the compressor pressure ratio; φ is the flow coefficient; ψ is the pressure coefficient; ρ is the gas density inside the compressor; A c ψ(φ, n) is the equivalent cross-sectional area of ​​the internal flow channel of the compressor; U is the linear velocity of the flange at the middle diameter of the compressor rotor; p0 is the ambient pressure; ψ(φ, n) is the compressor characteristic term; n is the compressor speed; a0, a1, b0, b1, c0, c1 are fitting coefficients; Step (2.2), based on the extended compressor characteristic surface, establish the compressor instability dynamic model as follows: Where u is the actuator control quantity input to the model; φ is the flow coefficient output by the model; ψ is the pressure coefficient output by the model; B is the dimensionless B parameter; l c γ is the compressor length; T This refers to the throttle valve opening. Step (2.3) uses a third-order Fourier series to fit the test data of the compressor tip static pressure under different surge margins, and establishes the tip static pressure model as follows: Among them, K i and S i The Fourier coefficients for the fit are derived from linear interpolation of the surge margin. For phase; N c σ is the compressor rotor speed; σ is the model correction coefficient, which is generally taken as 2 to 4. Step (3) constructs the actuator control module and calculates the impact of the jet actuator on the instability dynamic simulation module, that is, the impact of the jet actuator on the pressure coefficient ψ of the compressor instability dynamic model. j It can be expressed by the following formula: Among them, A j φ is the nozzle area of ​​the jet actuator. j Here, represents the flow coefficient of the jet device, and represents the input to the actuator control module. Step (4) Construct the parameter transfer relationship between each module, including the parameter transfer relationship between the steady-state and transient state simulation module of the aero-engine and the instability dynamic simulation module, and the parameter transfer relationship between the instability dynamic simulation module and the actuator control module.

2. The method for dynamic modeling of overall instability of an aero-engine according to claim 1, characterized in that... The steady-state and transient performance parameters are the pressure, flow rate, temperature, surge margin, and rotor speed at the inlet and outlet sections of each sub-component of the aero-engine.

3. The method for dynamic modeling of overall instability of an aero-engine according to claim 1, characterized in that... The parameter transfer relationship between the steady-state and transient state simulation module and the instability dynamic simulation module of the aero-engine is as follows: The component-level model of the aero-engine will have a rotor speed N c The dynamic model of compressor instability is passed to the compressor instability model. The engine rotor speed is the same as the compressor speed. The compressor instability dynamic model is calculated based on the compressor characteristic term ψ(φ, N) in the calculation model. c ); The component-level model of the aero-engine will have a rotor speed N c The surge margin SM and the compressor inlet section pressure P2 are transferred to the tip static pressure model to calculate the tip pressure P. tip =P2(C tip +1); The compressor instability dynamic model normalizes the output pressure coefficient φ and flow coefficient ψ, and then obtains the pressure influence coefficient C after Savitzky-Golay filtering. ψ and flow influence coefficient C φ Then C ψ C φ Transferred to the engine component-level model; After receiving the engine component-level model, the compressor outlet flow rate m3 and compressor outlet pressure P3 are multiplied by the pressure influence coefficient C, respectively. ψ and flow influence coefficient C φ .

4. The method for dynamic modeling of overall instability of an aero-engine according to claim 1, characterized in that... The parameter transfer relationship between the instability dynamic simulation module and the actuator control module is as follows: The actuator control module calculates the influence of the pressure coefficient ψ based on the flow coefficient φ from the received compressor instability dynamic model. j This is then passed to the compressor instability dynamic model, i.e., u = ψ j .

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