Simulink-based reciprocating compressor multi-physical field simulation method and system

Abstract

The invention discloses a multi-physical field simulation method and a multi-physical field simulation system for a reciprocating compressor based on simulink. Comprising the following steps: carrying out modular distinguishing on expansion, suction, compression and exhaust stages of the reciprocating compressor under normal working conditions by summarizing simulation parameters of the reciprocating compressor, carrying out physical modeling on different fault types, and according to a physical model of the reciprocating compressor after modular distinguishing, carrying out physical modeling on the reciprocating compressor; the method comprises the following steps of: writing and setting parameters through a simulink simulation language, verifying a simulink simulation calculation result, and optimizing and adjusting the parameters of the physical model of the reciprocating compressor through contrastive analysis, so that the physical model of the reciprocating compressor meets the actual working condition operation requirements. By integrating multiple physical field models such as dynamics, thermodynamics, fluid mechanics and air valve motion, complex dynamic behaviors of the compressor under various working conditions and fault states are comprehensively and truly simulated, and the limitation of traditional single physical field analysis is overcome.

Description

Technical Field

[0001] This invention relates to a dynamic simulation method for reciprocating compressors, specifically a multiphysics simulation method and system for reciprocating compressors based on Simulink, belonging to the field of dynamic simulation technology for reciprocating compressors. Background Technology

[0002] Reciprocating compressors are widely used in air conditioning, refrigeration, and gas transportation, and their operating status directly affects the performance and safety of the equipment. Current compressor monitoring and fault diagnosis largely rely on physical testing or large amounts of measured data, which is costly and difficult to comprehensively cover various operating conditions and fault types. With the development of simulation technology, using mathematical models to simulate the dynamic behavior of compressors has become an effective research method.

[0003] In the prior art, 1) an air conditioning compressor simulation method and system disclosed in CN107423477A, ​​the simulation method determines the air conditioning system simulation parameters by obtaining the system operating parameters and compressor operating parameters of the air conditioning system; and obtains simulation coefficients based on the air conditioning system simulation parameters and a simulation coefficient database, which is calculated by fitting based on the air conditioning operating parameters; and calculates the mass loss value and / or compressor power value of the air conditioning system based on the simulation coefficients, compression ratio, and dimensionless factor. The mass loss value and / or compressor power value of the air conditioning system calculated using this method have an error that can be controlled within 5% compared with the actual operating data of the air conditioning, thus improving the simulation of the air conditioning compressor. Accuracy, however, existing simulation methods only involve air conditioning operating parameters such as mass flow rate, suction pressure, exhaust enthalpy, suction enthalpy, speed, and displacement, which are limited to single physical field analysis. It is difficult to combine multiple physical field factors such as dynamics, thermodynamics, fluid mechanics and valve movement, and it is insufficient in fault simulation, and cannot fully reflect the actual fault characteristics; 2) For example, the natural gas engine-reciprocating compressor unit simulation system disclosed in CN101311988A has built an engine-compressor unit hardware simulation platform, but it relies on PLC logic control to realize start-stop operation training, does not involve multi-physical field coupling modeling, and fault simulation can only be triggered by preset scripts, lacking dynamic response at the mechanism level.

[0004] Therefore, there is an urgent need for an efficient simulation method that integrates multiphysics models and supports fault simulation, in order to assist in the design optimization, fault diagnosis and maintenance strategy formulation of compressors. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing compressor simulation technologies, such as insufficient single-physics analysis, lack of fault mechanism information, and complex model integration. It provides a Simulink-based multiphysics simulation method and system for reciprocating compressors, capable of simultaneously considering the interactions of multiple factors including dynamics, thermodynamics, fluid mechanics, and valve motion, thereby improving simulation accuracy and reliability. Furthermore, it overcomes the limitations of existing models in simulating multiple types of faults and lacking fault mechanism incorporation, providing a simulation system with fault simulation capabilities to support compressor design optimization, fault diagnosis, and maintenance strategy development, meeting the needs of modern intelligent manufacturing and predictive maintenance.

[0006] This invention achieves the above objective through the following technical solution: a multiphysics simulation method for reciprocating compressors based on Simulink, which includes the following steps:

[0007] S1. Summarize the simulation parameters of reciprocating compressors in specific application scenarios based on actual needs;

[0008] S2. Modularly distinguish the expansion stage, intake stage, compression stage and exhaust stage of the reciprocating compressor under normal operating conditions;

[0009] S3. Perform physical modeling for different fault types of reciprocating compressors;

[0010] S4. Based on the modularized reciprocating compressor physical model, the simulation is written and parameters are set using the Simulink simulation language to realize the simulation calculation of the reciprocating compressor in Simulink.

[0011] S5. Verify the Simulink simulation results. Through comparative analysis, optimize and adjust the parameters of the reciprocating compressor physical model so that the reciprocating compressor physical model meets the actual operating requirements.

[0012] S6. Introduce fault mechanism parameters into the physical model of the reciprocating compressor to simulate different types of fault states. Output key parameters and fault data through simulation to provide a simulation basis for fault diagnosis performance optimization.

[0013] As a further aspect of the present invention: when performing physical modeling, multiple fault models are preset, and multiple types of fault states are simulated by adjusting parameters or introducing fault mechanisms. The preset fault models include, but are not limited to, valve leakage, spring vibration, and gas leakage.

[0014] As a further aspect of the present invention: the effective flow area for valve leakage is bα sv A s Where b is the effective leakage flow area coefficient, and α svA is the valve gap flow coefficient. sv The valve seat channel area;

[0015] By rewriting the working model of the exhaust process, the working model of the expansion process under leakage conditions is obtained:

[0016] The working model of the expansion process under leakage conditions is as follows:

[0017]

[0018] In the formula, p cy p represents the cylinder pressure. s Indicates inhalation pressure, T represents the rate of change of cylinder pressure over time. s V represents the intake temperature. cy α represents the internal volume of the cylinder. sv A is the valve gap flow coefficient. sv Here, θ represents the valve seat passage area, k represents the adiabatic index of the ideal gas, θ represents the crank angle in degrees, ω represents the angular velocity of the crank rotation, and R represents the ideal gas constant.

[0019] The working model of the exhaust process under leakage conditions is as follows:

[0020]

[0021] In the formula, M v The valve plate's moving mass is represented by β, the spring thrust coefficient is represented by A. p The valve plate's surface area is represented by K, the valve plate spring stiffness by K, H0 by H0, the valve plate spring pre-compression by H, the piston displacement by h, and the valve plate's velocity by v. cy p represents the cylinder pressure. s Indicates inhalation pressure, T represents the rate of change of cylinder pressure over time. S V represents the intake temperature. cy Indicates the internal volume of the cylinder. α represents the rate of change of the cylinder's internal volume over time. Sv A is the valve gap flow coefficient. sv Here, θ represents the valve seat passage area, k represents the adiabatic index of the ideal gas, θ represents the crank angle in degrees, ω represents the angular velocity of the crank rotation, and R represents the ideal gas constant.

[0022] The mathematical formulas described above are converted into Simulink language to form a working state model of the reciprocating compressor under fault conditions.

[0023] A multiphysics simulation system for a reciprocating compressor based on Simulink includes a physical model of the reciprocating compressor, which is modularly divided into an expansion stage, an intake stage, a compression stage, and an exhaust stage.

[0024] The expansion and compression stages of the physical model of the reciprocating compressor include a crank angle calculation module, a cylinder control volume calculation module, a cylinder temperature calculation module, and a pressure / volume / heat exchange calculation module.

[0025] The intake and exhaust phases of the reciprocating compressor physical model include a crank angle calculation module, a cylinder control volume calculation module, a cylinder temperature calculation module, a volume / heat exchange / gas mass calculation module, and a valve plate motion calculation module.

[0026] The crank angle calculation module and the cylinder control volume calculation module are used to simulate the crank and piston movement process of a reciprocating compressor.

[0027] The in-cylinder temperature calculation module, pressure / volume / heat exchange calculation module, and volume / heat exchange / gas mass calculation module are used to simulate the thermodynamic cycle of a reciprocating compressor.

[0028] The valve plate motion calculation module is used to simulate the opening and closing motion of the valve during the intake and exhaust process of a reciprocating compressor.

[0029] As a further aspect of the present invention: the crank angle calculation module describes the motion process of the crank and piston of the reciprocating compressor using the following formula:

[0030]

[0031] In the formula, V is the control volume of the cylinder, D is the cylinder diameter, S is the piston stroke, λ is the crank radius connecting rod ratio, i.e., λ=r / L, V0 is the cylinder clearance volume, and θ is the crank angle.

[0032] The above mathematical formulas are converted into Simulink language to form a cylinder control volume calculation module, which is then connected to the cylinder temperature calculation module, pressure / volume / heat exchange calculation module, and valve plate motion calculation module.

[0033] As a further aspect of the present invention: the in-cylinder temperature calculation module describes the change law of in-cylinder temperature according to the following formula:

[0034]

[0035] In the formula, This represents the heat exchanged between the cylinder and the outside environment. This indicates the change in gas energy inside the cylinder. This indicates the energy released due to exhaust. This represents the energy that flows in due to inhalation. The expression represents the work done by the gas on its surroundings, where h represents the enthalpy of the gas and v represents the gas velocity.

[0036] The above mathematical formulas are translated into Simulink language to form an in-cylinder temperature calculation module, which is connected to the cylinder control volume calculation module and the pressure / volume / heat exchange calculation module to form expansion and compression stage models. The expansion and compression stage models are described by the following formulas:

[0037]

[0038] In the formula, p cy T represents the cylinder pressure. cy V represents the temperature of the gas inside the cylinder. cy T represents the cylinder's internal volume, and T represents the instantaneous temperature of the gas inside the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. This indicates the rate of change of the cylinder's internal volume over time.

[0039] γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface, while k represents the adiabatic index of an ideal gas.

[0040] As a further aspect of the present invention: the cylinder pressure / volume / heat exchange calculation module is used to describe the pressure change process inside the cylinder during the operation of the reciprocating compressor, and the following formula describes the gas pressure change law:

[0041] PV m =C

[0042] In the formula, C is a fixed quantity, m is the polytropic process index, and P and V are the pressure and volume of the gas in the cylinder at any given time.

[0043] The above mathematical formulas are converted into Simulink language to form a cylinder pressure / volume / heat exchange calculation module, which is connected with the cylinder temperature calculation module and the cylinder control volume calculation module to form an expansion stage and compression stage model.

[0044] The expansion and compression phases are described by the following equation:

[0045]

[0046] In the formula, p cy T represents the cylinder pressure. cyV represents the temperature of the gas inside the cylinder. cy T represents the cylinder's internal volume, and T represents the instantaneous temperature of the gas inside the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. This indicates the rate of change of the cylinder's internal volume over time.

[0047] γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface, while k represents the adiabatic index of an ideal gas.

[0048] As a further aspect of the present invention: the valve plate motion calculation module is used to describe the motion law of the gas valve and the change law of the cylinder pressure during the intake and exhaust phases of the reciprocating compressor during its operation.

[0049] According to Bernoulli's law, the outlet velocity of the gas after passing through the valve gap can be calculated and expressed by the following formula:

[0050]

[0051] In the formula, u svo The outlet velocity, h, represents the gas velocity after passing through the valve gap. s h represents the enthalpy of the gas before it flows through the valve gap. svo The value represents the enthalpy of the gas after it flows through the valve gap, k represents the adiabatic index of the ideal gas, R represents the gas constant, and T represents the enthalpy of the gas after it flows through the valve gap. s p represents the temperature of the gas before it flows through the valve gap. cy p represents the gas pressure inside the cylinder. s This indicates the pressure of the gas before it flows through the valve gap;

[0052] The above mathematical formulas are translated into Simulink language, and the valve plate motion calculation module is connected to the cylinder pressure / volume / heat transfer calculation module to form the intake and exhaust stage models. The intake and exhaust stage models are described by the following formulas:

[0053]

[0054] In the formula, M v The moving mass of the valve plate is represented by β, the spring thrust coefficient, and A. p The valve plate's surface area is represented by K, the valve plate spring stiffness by K, H0 by H0, the valve plate spring pre-compression by H, the piston displacement by h, and the valve plate's velocity by v. cy p represents the cylinder pressure. s T represents inspiratory pressure. cyT represents the cylinder gas temperature, and T represents the instantaneous cylinder gas temperature. s V represents the intake temperature. cy Indicates the internal volume of the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. α represents the rate of change of the cylinder's internal volume over time. sv A is the valve gap flow coefficient. sv The valve seat channel area;

[0055] γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface; k represents the adiabatic index of an ideal gas.

[0056] The above mathematical formulas are converted into Simulink language to form a model of the intake and exhaust stages of a reciprocating compressor under normal operating conditions.

[0057] The beneficial effects of this invention are:

[0058] 1. Significantly improve simulation accuracy and realism: By integrating multi-physics models such as dynamics, thermodynamics, fluid mechanics and valve motion, it comprehensively and realistically simulates the complex dynamic behavior of the compressor under various operating conditions and fault states, overcoming the limitations of traditional single-physics analysis;

[0059] 2. Simulation and analysis of multiple types of faults: By introducing fault mechanism parameters (such as valve leakage, vibration, etc.), multiple fault types can be accurately simulated in the simulation, providing rich simulation samples for fault diagnosis, prediction and maintenance, and improving the accuracy and efficiency of fault identification.

[0060] 3. Supports design optimization: The simulation model can run quickly under different parameter conditions, helping engineers optimize compressor design parameters, identify potential failure risks in advance, thereby reducing R&D costs and improving equipment safety and reliability;

[0061] 4. Facilitates system integration and automation: Based on the MATLAB / Simulink platform, the system has good scalability and automated simulation capabilities, making it easy to integrate with other simulation tools or control systems to meet the application needs of intelligent manufacturing and predictive maintenance. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the multiphysics simulation method for reciprocating compressors based on Simulink, as described in this invention.

[0063] Figure 2 This is a schematic diagram of the simulation method for the expansion and compression process of the reciprocating compressor of the present invention;

[0064] Figure 3 This is a schematic diagram of the simulation method for the intake and exhaust process of the reciprocating compressor of the present invention;

[0065] Figure 4 This is a simulation result diagram of the pressure change inside the cylinder of the reciprocating compressor of the present invention;

[0066] Figure 5 This is a simulation result diagram of the temperature change inside the cylinder of the reciprocating compressor of the present invention;

[0067] Figure 6 This is a simulation result diagram of the motion law of the intake and exhaust valves of the reciprocating compressor in this invention example;

[0068] Figure 7 This is a simulation result of the change in the discharge pressure inside the cylinder of a reciprocating compressor under the condition of a leakage fault in the intake valve of the present invention.

[0069] Figure 8 The figure shows the simulation results of the intake pressure change in the reciprocating compressor under the spring vibration fault condition of the present invention.

[0070] In the diagram: 1. Crank angle calculation module; 2. Cylinder control volume calculation module; 3. Cylinder temperature calculation module; 4. Pressure / volume / heat exchange calculation module; 5. Volume / heat exchange / gas mass calculation module; 6. Valve plate motion calculation module. Detailed Implementation

[0071] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0072] Example 1, as Figure 1 As shown, a multiphysics simulation method for a reciprocating compressor based on Simulink is presented. This multiphysics simulation method includes the following steps:

[0073] S1. Summarize the simulation parameters of reciprocating compressors in specific application scenarios based on actual needs;

[0074] S2. Modularly distinguish the expansion stage, intake stage, compression stage and exhaust stage of the reciprocating compressor under normal operating conditions;

[0075] S3. Perform physical modeling for different fault types of reciprocating compressors;

[0076] S4. Based on the modularized reciprocating compressor physical model, the simulation is written and parameters are set using the Simulink simulation language to realize the simulation calculation of the reciprocating compressor in Simulink.

[0077] S5. Verify the Simulink simulation results. Through comparative analysis, optimize and adjust the parameters of the reciprocating compressor physical model so that the reciprocating compressor physical model meets the actual operating requirements.

[0078] S6. Introduce fault mechanism parameters into the physical model of the reciprocating compressor to simulate different types of fault states. Output key parameters and fault data through simulation to provide a simulation basis for fault diagnosis performance optimization.

[0079] Example 2, in addition to all the technical features included in Example 1, also includes:

[0080] When performing physical modeling, multiple fault models are preset and introduced through parameter adjustment or fault mechanism to realize the simulation of multiple types of fault states, so as to enrich the fault dataset. The preset fault models include, but are not limited to, valve leakage, spring vibration and gas leakage.

[0081] The effective flow area for valve leakage is bα sv A Sv Where b is the effective leakage flow area coefficient, and α sv A is the valve gap flow coefficient. sv The valve seat channel area;

[0082] By rewriting the working model of the exhaust process, the working model of the expansion process under leakage conditions is obtained:

[0083] The working model of the expansion process under leakage conditions is as follows:

[0084]

[0085] In the formula, p cy p represents the cylinder pressure. s Indicates inhalation pressure, T represents the rate of change of cylinder pressure over time. s V represents the intake temperature. cy α represents the internal volume of the cylinder. sv A is the valve gap flow coefficient. sv Here, θ represents the valve seat passage area, k represents the adiabatic index of the ideal gas, θ represents the crank angle in degrees, ω represents the angular velocity of the crank rotation, and R represents the ideal gas constant.

[0086] The working model of the exhaust process under leakage conditions is as follows:

[0087]

[0088] In the formula, M v The valve plate's moving mass is represented by β, the spring thrust coefficient is represented by A. p The valve plate's surface area is represented by K, the valve plate spring stiffness by K, H0 by H0, the valve plate spring pre-compression by H, the piston displacement by h, and the valve plate's velocity by v. cy p represents the cylinder pressure. s Indicates inhalation pressure, T represents the rate of change of cylinder pressure over time. s V represents the intake temperature. cy Indicates the internal volume of the cylinder. α represents the rate of change of the cylinder's internal volume over time. sv A is the valve gap flow coefficient. sv Here, θ represents the valve seat passage area, k represents the adiabatic index of the ideal gas, θ represents the crank angle in degrees, ω represents the angular velocity of the crank rotation, and R represents the ideal gas constant.

[0089] The mathematical formulas described above are converted into Simulink language to form a working state model of the reciprocating compressor under fault conditions.

[0090] Due to the presence of the leakage hole, the cylinder is not in a closed state during the expansion and compression cycle. This process is similar to the intake and exhaust process. By adjusting the effective flow area coefficient b, different degrees of valve leakage failure can be simulated. By adjusting the valve spring stiffness parameter K during the intake and exhaust process, different degrees of spring vibration failure can be simulated.

[0091] Example 3, as Figures 2 to 8 As shown, a Simulink-based multiphysics simulation system for a reciprocating compressor includes a physical model of the reciprocating compressor. The physical model is modularly divided into an expansion stage, an intake stage, a compression stage, and an exhaust stage. The expansion and compression stages of the physical model include a crank angle calculation module 1, a cylinder control volume calculation module 2, a cylinder temperature calculation module 3, and a pressure / volume / heat transfer calculation module 4. The intake and exhaust stages of the physical model include a crank angle calculation module 1, a cylinder control volume calculation module 2, a cylinder temperature calculation module 3, a volume / heat transfer / gas mass calculation module 5, and a valve plate motion calculation module 6.

[0092] Crank angle calculation module 1 and cylinder control volume calculation module 2 are used to simulate the crank and piston movement process of a reciprocating compressor.

[0093] The cylinder temperature calculation module 3, pressure / volume / heat exchange calculation module 4, and volume / heat exchange / gas mass calculation module 5 are used to simulate the thermodynamic cycle process of a reciprocating compressor.

[0094] The valve plate motion calculation module 6 is used to simulate the opening and closing motion of the valve during the intake and exhaust process of a reciprocating compressor.

[0095] Example 4, in addition to all the technical features included in Example 3, also includes:

[0096] Crank angle calculation module 1 describes the motion process of the crank and piston in a reciprocating compressor using the following formula:

[0097]

[0098] In the formula, V is the control volume of the cylinder, D is the cylinder diameter, S is the piston stroke, λ is the crank radius connecting rod ratio, i.e., λ=r / L, V0 is the cylinder clearance volume, and θ is the crank angle.

[0099] The above mathematical formulas are converted into Simulink language to form cylinder control volume calculation module 1, which is then connected to cylinder temperature calculation module 2, pressure / volume / heat exchange calculation module 3, and valve plate motion calculation module 4.

[0100] The cylinder temperature calculation module 2 describes the variation law of cylinder temperature according to the following formula:

[0101]

[0102] In the formula, This represents the heat exchanged between the cylinder and the outside environment. This indicates the change in gas energy inside the cylinder. This indicates the energy released due to exhaust. This represents the energy that flows in due to inhalation. The expression represents the work done by the gas on its surroundings, where h represents the enthalpy of the gas and v represents the gas velocity.

[0103] The above mathematical formulas are converted into Simulink language to form the in-cylinder temperature calculation module 2, which is connected to the cylinder control volume calculation module 1 and the pressure / volume / heat exchange calculation module 3 to form the expansion and compression stage model. The expansion and compression stage model is described by the following formula:

[0104]

[0105] In the formula, p cy T represents the cylinder pressure. cy V represents the temperature of the gas inside the cylinder. cy T represents the cylinder's internal volume, and T represents the instantaneous temperature of the gas inside the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. This indicates the rate of change of the cylinder's internal volume over time.

[0106] γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface, while k represents the adiabatic index of an ideal gas.

[0107] The cylinder pressure / volume / heat transfer calculation module 3 is used to describe the pressure change process inside the cylinder during the operation of the reciprocating compressor. Since the gas mass does not change during the compression and expansion stages, it can be considered a closed system, which is a polytropic process. The following formula describes the gas pressure change pattern:

[0108] PV m =C

[0109] In the formula, C is a fixed quantity, m is the polytropic process index, and P and V are the pressure and volume of the gas in the cylinder at any given time.

[0110] The above mathematical formulas are converted into Simulink language to form cylinder pressure / volume / heat transfer calculation module 3, which is connected to cylinder temperature calculation module 2 and cylinder control volume calculation module 1 to form an expansion and compression stage model; the expansion and compression stage model is described by the following formula:

[0111]

[0112] In the formula, p cy T represents the cylinder pressure. cy V represents the temperature of the gas inside the cylinder. cy T represents the cylinder's internal volume, and T represents the instantaneous temperature of the gas inside the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. This indicates the rate of change of the cylinder's internal volume over time.

[0113] γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface, while k represents the adiabatic index of an ideal gas.

[0114] The valve plate motion calculation module 4 is used to describe the motion law of the gas valve and the change law of cylinder pressure during the intake and exhaust phases of the reciprocating compressor. The gas valve can be simplified as a throttling orifice. According to Bernoulli's law, the outlet velocity of the gas after flowing through the valve gap can be calculated and expressed by the following formula:

[0115]

[0116] In the formula, u svo The outlet velocity, h, represents the gas velocity after passing through the valve gap. s h represents the enthalpy of the gas before it flows through the valve gap. svo The value represents the enthalpy of the gas after it flows through the valve gap, k represents the adiabatic index of the ideal gas, R represents the gas constant, and T represents the enthalpy of the gas after it flows through the valve gap. s p represents the temperature of the gas before it flows through the valve gap. cy p represents the gas pressure inside the cylinder. s This indicates the pressure of the gas before it flows through the valve gap;

[0117] The above mathematical formulas are converted into Simulink language, and the valve plate motion calculation module 4 is connected to the cylinder pressure / volume / heat transfer calculation module 3 to form the intake and exhaust stage models. The intake and exhaust stage models are described by the following formula:

[0118]

[0119] In the formula, M v The moving mass of the valve plate is represented by β, the spring thrust coefficient, and A. p The valve plate's surface area is represented by K, the valve plate spring stiffness by K, H0 by H0, the valve plate spring pre-compression by H, the piston displacement by h, and the valve plate's velocity by v. cy p represents the cylinder pressure. s T represents inspiratory pressure. cy T represents the cylinder gas temperature, and T represents the instantaneous cylinder gas temperature. s V represents the intake temperature. cy Indicates the internal volume of the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. α represents the rate of change of the cylinder's internal volume over time. sv A is the valve gap flow coefficient. sv The valve seat channel area;

[0120] γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A kThis represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface; k represents the adiabatic index of an ideal gas.

[0121] The above mathematical formulas are converted into Simulink language to form a model of the intake and exhaust stages of a reciprocating compressor under normal operating conditions.

[0122] Working Principle: The working cycle begins with crank angle module 1, which calculates piston displacement and outputs the volume change rate to the thermodynamics module in real time. During the expansion / compression phase, cylinder control volume module 2 receives the crank angle signal and drives pressure / volume / heat transfer module 4 to solve the variable process of the closed system. Simultaneously, cylinder pressure / volume / heat transfer calculation module 3 solves the energy equation and state equation simultaneously, coupling the cylinder wall temperature field through the heat conduction term. During the intake / exhaust phase, volume / heat transfer / gas mass module 5 turns the system into an open system. Valve plate motion module 6 dynamically calculates the valve gap velocity based on the pressure difference and corrects the mass flow rate term. Cylinder pressure / volume / heat transfer calculation module 3 updates the equations synchronously, adding an energy term driven by gas inflow. Fault injection is achieved by modifying key parameters: when simulating valve leakage, a leakage term is superimposed on the pressure equation during the exhaust phase; for spring chatter faults, the stiffness coefficient of the valve plate motion equation is modified, causing the opening delay time to fluctuate randomly. Finally, all module output parameters (pressure / temperature curves, valve displacement) are imported into the Simulink solver to generate multiphysics time-series data with fault markers.

[0123] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0124] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multiphysics simulation method for a reciprocating compressor based on Simulink, characterized in that, The multiphysics simulation method includes the following steps: S1. Summarize the simulation parameters of reciprocating compressors in specific application scenarios based on actual needs; S2. Modularly distinguish the expansion stage, intake stage, compression stage and exhaust stage of the reciprocating compressor under normal operating conditions; S3. Perform physical modeling for different fault types of reciprocating compressors; S4. Based on the modularized reciprocating compressor physical model, the simulation is written and parameters are set using the Simulink simulation language to realize the simulation calculation of the reciprocating compressor in Simulink. S5. Verify the Simulink simulation results. Through comparative analysis, optimize and adjust the parameters of the reciprocating compressor physical model so that the reciprocating compressor physical model meets the actual operating requirements. S6. Introduce fault mechanism parameters into the physical model of the reciprocating compressor to simulate different types of fault states. Output key parameters and fault data through simulation to provide a simulation basis for fault diagnosis performance optimization.

2. The multiphysics simulation method for reciprocating compressors according to claim 1, characterized in that: In S3, when performing physical modeling, multiple fault models are preset, and multiple types of fault states are simulated by adjusting parameters or introducing fault mechanisms. The preset fault models include, but are not limited to, valve leakage, spring vibration, and gas leakage.

3. The multiphysics simulation method for reciprocating compressors according to claim 2, characterized in that: The effective flow area for leakage in the gas valve is bα sv A sv Where b is the effective leakage flow area coefficient, and α sv A is the valve gap flow coefficient. sv The valve seat channel area; By rewriting the working model of the exhaust process, the working model of the expansion process under leakage conditions is obtained: The working model of the expansion process under leakage conditions is as follows: In the formula, p cy p represents the cylinder pressure. s Indicates inhalation pressure, T represents the rate of change of cylinder pressure over time. s V represents the intake temperature. cy α represents the internal volume of the cylinder. sv A is the valve gap flow coefficient. sv Here, θ represents the valve seat passage area, k represents the adiabatic index of the ideal gas, θ represents the crank angle in degrees, ω represents the angular velocity of the crank rotation, and R represents the ideal gas constant. The working model of the exhaust process under leakage conditions is as follows: In the formula, M v The valve plate's moving mass is represented by β, the spring thrust coefficient is represented by A. p The valve plate's surface area is represented by K, the valve plate spring stiffness by K, H0 by H0, the valve plate spring pre-compression by H, the piston displacement by h, and the valve plate's velocity by v. cy p represents the cylinder pressure. s Indicates inhalation pressure, T represents the rate of change of cylinder pressure over time. s V represents the intake temperature. cy Indicates the internal volume of the cylinder. α represents the rate of change of the cylinder's internal volume over time. sv A is the valve gap flow coefficient. sv Here, θ represents the valve seat passage area, k represents the adiabatic index of the ideal gas, θ represents the crank angle in degrees, ω represents the angular velocity of the crank rotation, and R represents the ideal gas constant. The mathematical formulas described above are converted into Simulink language to form a working state model of the reciprocating compressor under fault conditions.

4. A Simulink-based multiphysics simulation system for a reciprocating compressor, comprising the physical model of the reciprocating compressor as described in claims 1 to 3, characterized in that: The reciprocating compressor physical model is modularly divided into an expansion stage, an intake stage, a compression stage, and an exhaust stage. The expansion and compression stages of the physical model of the reciprocating compressor include a crank angle calculation module (1), a cylinder control volume calculation module (2), a cylinder temperature calculation module (3), and a pressure / volume / heat exchange calculation module (4). The intake and exhaust phases of the physical model of the reciprocating compressor include a crank angle calculation module (1), a cylinder control volume calculation module (2), a cylinder temperature calculation module (3), a volume / heat exchange / gas mass calculation module (5), and a valve plate motion calculation module (6). The crank angle calculation module (1) and the cylinder control volume calculation module (2) are used to simulate the crank and piston movement process of a reciprocating compressor. The cylinder temperature calculation module (3), pressure / volume / heat exchange calculation module (4), and volume / heat exchange / gas mass calculation module (5) are used to simulate the thermodynamic cycle of a reciprocating compressor. The valve plate motion calculation module (6) is used to simulate the opening and closing motion process of the air valve during the intake and exhaust process of the reciprocating compressor.

5. The multiphysics simulation system for reciprocating compressors according to claim 4, characterized in that: The crank angle calculation module (1) describes the motion process of the crank and piston of the reciprocating compressor using the following formula: In the formula, V is the control volume of the cylinder, D is the cylinder diameter, S is the piston stroke, λ is the crank radius connecting rod ratio, i.e., λ=r / L, V0 is the cylinder clearance volume, and θ is the crank angle. The above mathematical formulas are converted into Simulink language to form a cylinder control volume calculation module (1), which is then connected to the cylinder temperature calculation module (2), pressure / volume / heat exchange calculation module (3), and valve plate motion calculation module (4).

6. The multiphysics simulation system for reciprocating compressors according to claim 4, characterized in that: The in-cylinder temperature calculation module (2) describes the change law of in-cylinder temperature according to the following formula: In the formula, This represents the heat exchanged between the cylinder and the outside environment. This indicates the change in gas energy inside the cylinder. This indicates the energy released due to exhaust. This represents the energy that flows in due to inhalation. The expression represents the work done by the gas on its surroundings, where h represents the enthalpy of the gas and v represents the gas velocity. The above mathematical formulas are converted into Simulink language to form an in-cylinder temperature calculation module (2), which is connected to the cylinder control volume calculation module (1) and the pressure / volume / heat exchange calculation module (3) to form an expansion stage and compression stage model. The expansion and compression phases are described by the following equation: In the formula, p cy T represents the cylinder pressure. cy V represents the temperature of the gas inside the cylinder. cy T represents the cylinder's internal volume, and T represents the instantaneous temperature of the gas inside the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. This indicates the rate of change of the cylinder's internal volume over time. γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface, while k represents the adiabatic index of an ideal gas.

7. The multiphysics simulation system for reciprocating compressors according to claim 4, characterized in that: The cylinder pressure / volume / heat exchange calculation module (3) is used to describe the pressure change process inside the cylinder during the operation of the reciprocating compressor. The following formula describes the change law of gas pressure: PV m =C In the formula, C is a fixed quantity, m is the polytropic process index, and P and V are the pressure and volume of the gas in the cylinder at any given time. The above mathematical formulas are converted into Simulink language to form a cylinder pressure / volume / heat exchange calculation module (3), which is connected to the cylinder temperature calculation module (2) and the cylinder control volume calculation module (1) to form an expansion stage and compression stage model. The expansion and compression phases are described by the following equation: In the formula, p cy T represents the cylinder pressure. cy V represents the temperature of the gas inside the cylinder. cy T represents the cylinder's internal volume, and T represents the instantaneous temperature of the gas inside the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. This indicates the rate of change of the cylinder's internal volume over time. γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface, while k represents the adiabatic index of an ideal gas.

8. The multiphysics simulation system for reciprocating compressors according to claim 4, characterized in that: The valve plate motion calculation module (4) is used to describe the motion law of the gas valve and the change law of the cylinder pressure during the intake and exhaust stages of the reciprocating compressor. According to Bernoulli's law, the outlet velocity of the gas after passing through the valve gap is obtained and expressed by the following formula: In the formula, u svo The outlet velocity, h, represents the gas velocity after passing through the valve gap. s h represents the enthalpy of the gas before it flows through the valve gap. svo The value represents the enthalpy of the gas after it flows through the valve gap, k represents the adiabatic index of the ideal gas, R represents the gas constant, and T represents the enthalpy of the gas after it flows through the valve gap. s p represents the temperature of the gas before it flows through the valve gap. cy p represents the gas pressure inside the cylinder. s This indicates the pressure of the gas before it flows through the valve gap; The above mathematical formulas are converted into Simulink language, and the valve plate motion calculation module (4) is connected to the cylinder pressure / volume / heat transfer calculation module (3) to form the intake and exhaust stage model. The intake and exhaust stage model is described by the following formula: In the formula, M v The moving mass of the valve plate is represented by β, the spring thrust coefficient, and A. p The valve plate's surface area is represented by K, the valve plate spring stiffness by K, H0 by H0, the valve plate spring pre-compression by H, the piston displacement by h, and the valve plate's velocity by v. cy p represents the cylinder pressure. s T represents inspiratory pressure. cy T represents the cylinder gas temperature, and T represents the instantaneous cylinder gas temperature. s V represents the intake temperature. cy Indicates the internal volume of the cylinder. This indicates the rate of change of cylinder pressure over time. This indicates the rate of change of cylinder temperature over time. α represents the rate of change of the cylinder's internal volume over time. sv A is the valve gap flow coefficient. sv The valve seat channel area; γ represents the heat transfer coefficient. A represents the average temperature of the cylinder mirror surface, piston surface, and cylinder head surface. r A n A k This represents the heat exchange area of ​​the cylinder mirror surface, piston surface, and cylinder head surface; k represents the adiabatic index of an ideal gas. The above mathematical formulas are converted into Simulink language to form a model of the intake and exhaust stages of a reciprocating compressor under normal operating conditions.

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