A simulation method and device for engine surge test

Abstract

A simulation method and device for engine surge test, the method comprising: establishing a model for a compressor, a combustion chamber, a turbine and a surge system of an engine respectively; performing a whole engine surge simulation, comprising: setting input parameters of the models, running the models to simulate the compressor, the combustion chamber, the turbine and the surge system, obtaining data of the engine changing with time; and determining whether the engine enters surge according to the data of the engine changing with time. The disclosure also provides a device capable of implementing the above method. The simulation method and device of the embodiments of the disclosure are effective means for actual whole engine surge test parameter design and evaluation.

Description

[0001] Cross-references to related applications This disclosure claims priority to Chinese patent application No. 202210524779.1, filed with the China National Intellectual Property Administration on May 13, 2022, entitled "A Simulation Method and Apparatus for Engine Breathing Test", the contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates to, but is not limited to, the field of engines; more specifically, it relates to a simulation method and apparatus for engine power surge testing. Background Technology

[0003] Engines (such as aero engines) may experience surge during actual operation. Surge not only leads to a severe deterioration in engine performance but also poses a significant threat to structural integrity. In engineering, to determine the surge boundary of an engine—that is, to clarify under what operating conditions an engine will experience surge—controlled surge reproduction is often achieved through bench testing, also known as forced surge testing.

[0004] On a complete engine test bench, obtaining the surge boundary through whole-engine surge testing is very difficult. This is mainly due to the limitations imposed by the matching operation of the compressor and turbine. The steady-state operating point of the engine can only move along a common operating line, unlike component testing where the operating point can be freely adjusted. Currently, there are four main methods for whole-engine surge testing: 1) High-pressure gas surge method: This method involves injecting high-pressure gas after the compressor to increase the actual back pressure of the compressor, thereby causing the operating point to move towards the surge boundary; 2) Fuel step surge method: This method increases the turbine inlet temperature by instantaneously increasing the fuel injection quantity, resulting in an instantaneous increase in the turbine equivalent flow rate (while the rotational speed remains essentially constant due to inertia), increasing the turbine inlet pressure, and thus increasing the actual back pressure of the compressor, thereby causing the transient operating point to move towards the surge boundary; 3) Variable geometry surge method: This method increases the turbine inlet pressure by reducing the turbine throat area, thereby increasing the actual back pressure of the compressor, and thus causing the operating point to move towards the surge boundary; 4) Water injection surge method: This method involves atomizing water after the compressor to form water vapor, thereby increasing the actual back pressure of the compressor. Regardless of the method, the goal is to create a high back pressure condition at the compressor outlet on the entire engine, causing the operating point to shift towards the surge boundary.

[0005] However, the aforementioned testing methods not only require dangerous forced-surge tests on a real engine, but also necessitate modifications to the engine to varying degrees. This is not only difficult and expensive, but also carries high risks. On the one hand, to control costs and reduce risks, the number of forced-surge tests must be minimized as much as possible; on the other hand, the numerous test parameters and engine operating conditions require extensive testing for optimization and iteration. Summary of the Invention

[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0007] This disclosure provides a simulation method for engine breathing test, including: Models were created for the engine's compressor, combustion chamber, turbine, and exhaust system. The process of performing a full-engine surge simulation includes: setting the input parameters of the model, running the model to simulate the compressor, combustion chamber, turbine and surge system, and obtaining data on the change of engine inlet flow rate over time. The engine is determined to have entered surge mode based on the data on the change of engine inlet flow over time.

[0008] This disclosure also provides a simulation device for an engine breathing test, including a processor and a memory storing a computer program, wherein the processor, when executing the computer program, can implement the simulation method for an engine breathing test as described in any embodiment of this disclosure.

[0009] The embodiments disclosed herein can simulate the process of whole-machine surge test and obtain the surge boundary of the whole machine, which is an effective means of designing and evaluating actual whole-machine surge test parameters.

[0010] After reading and understanding the accompanying diagrams and detailed descriptions, other aspects can be understood. Attached Figure Description

[0011] Figure 1 This is a flowchart of a simulation method for an engine surge test according to an embodiment of the present disclosure; Figure 2 This is a schematic diagram of a simulation method for an engine surge test according to an embodiment of the present disclosure; Figure 3 This is a block diagram of an engine over-breathing model according to an embodiment of the present disclosure; Figure 4 This is a partial schematic diagram of the computational domain of a compressor model according to an embodiment of this disclosure; Figure 5A and Figure 5B This is a schematic diagram illustrating the bidirectional information transfer between a compressor model (three-dimensional model) and a combustion chamber model (one-dimensional model) according to an embodiment of this disclosure; Figure 6 This is a schematic diagram illustrating an embodiment of the present disclosure using SMF parameters to determine engine surge. Figure 7 This is a schematic diagram of the engine surge boundary and surge dynamic characteristics under different inflation parameters according to an embodiment of this disclosure. Detailed Implementation

[0012] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this disclosure.

[0013] In the description of this disclosure, the words "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment described as "exemplary" or "for example" in this disclosure should not be construed as being more preferred or advantageous than other embodiments. The word "and / or" in this document describes an association relationship between related objects, indicating that three relationships may exist, for example, A and / or B, which can represent: A alone, A and B simultaneously, and B alone. In the description of this disclosure, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0014] The technical solutions of the various embodiments of this disclosure can be combined with each other, but are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this disclosure.

[0015] As mentioned earlier, obtaining surge boundaries by conducting whole-engine surge tests on an engine test bench is very difficult. There is an urgent need to realize the function of whole-engine surge testing through numerical simulation methods, but currently there is no solution that can realize whole-engine surge simulation, and other simulation methods for whole engines all suffer from high computational costs and extremely long computation times.

[0016] In view of this, one embodiment of this disclosure provides a simulation method for engine power surge testing, such as... Figure 1 As shown, it includes: Step 110: Establish models for the engine's compressor, combustion chamber, turbine, and exhaust system, respectively. Step 120, perform engine over-breathing simulation, including: setting the input parameters of the model, running the model to simulate the compressor, combustion chamber, turbine and over-breathing system, and obtaining data on the change of engine flow rate over time; Step 130: Determine whether the engine has entered surge based on the data of the engine flow rate changing over time.

[0017] In an exemplary embodiment of this disclosure, models are respectively established for the compressor, combustion chamber, turbine, and exhaust system of the engine, wherein, A three-dimensional volumetric force model capable of simulating surge is established for the compressor, and the three-dimensional volumetric force model has a three-dimensional computational domain; The compressor model established for the compressor is a three-dimensional volumetric force model capable of simulating surge. The combustion chamber model established for the combustion chamber is a one-dimensional model of coupled cavity exothermic effects; The turbine model established for the turbine is a zero-dimensional model coupled with the throat blockage effect; The breathing system model established for the breathing system simulates the high-pressure breathing system in the form of the inflation boundary conditions of the compressor model.

[0018] In an exemplary embodiment of this disclosure, the inlet boundary of the combustion chamber model is the outlet boundary of the compressor model, and the outlet boundary of the combustion chamber model is the inlet of the turbine model; The combustion chamber model includes the cavity equation of the combustion chamber with heat source, and the outlet boundary of the combustion chamber model contains the critical equation of turbine throat blockage in the turbine model. The turbine model is solved in conjunction with the outlet boundary conditions of the combustion chamber model. The breathing system model simulates the inflation port for high-pressure gas by setting one or more inflation boundaries on the computational domain of the compressor model corresponding to the compressor casing position. The inflation boundary conditions are set to use a constant total temperature and time-varying total pressure total temperature and total pressure condition.

[0019] In this embodiment, when iteratively calculating the nodes at the outlet boundary of the combustion chamber model, the flow control equations of the combustion chamber, the equations of the combustion chamber cavity with heat source, and the critical equations for turbine throat blockage are solved simultaneously. This is equivalent to establishing a zero-dimensional model for the combustion chamber cavity, represented by the cavity equations with heat source. Both this zero-dimensional combustion chamber cavity model and the zero-dimensional turbine model are coupled to the outlet boundary of the one-dimensional computational domain of the combustion chamber. From the perspective of boundary conditions, it can be said that the flow control equations of the combustion chamber and the equations of the combustion chamber cavity with heat source are used as the boundary conditions for the outlet boundary of the combustion chamber model.

[0020] The model established in this embodiment for the engine's compressor, combustion chamber, turbine, and surge system can be collectively referred to as the engine's overall surge model. Figure 3As shown, the overall engine surge model includes a compressor model based on the compressor itself and a combustion chamber model based on the combustion chamber downstream of the compressor. The compressor model employs a three-dimensional volumetric force model with a three-dimensional computational domain, which can be solved using the finite volume method. The combustion chamber model employs a one-dimensional model coupled with cavity exothermic effects, with a one-dimensional computational domain, which can be solved using the method of characteristics. The turbine model employs a zero-dimensional model coupled with throat blockage effects, solved by coupling it to the outlet boundary conditions of the combustion chamber model. The surge system model is a high-pressure charging system simulated using the charging boundary conditions of the compressor model.

[0021] Figure 3 A block diagram of the overall simulation model is provided, which can also be used to illustrate a simplified simulation calculation process. Parameters pointing from outside the dashed box to inside the dashed box are the model's input parameters, while the part inside the dashed box represents the part automatically calculated by the model based on the input parameters. Parameters pointing from inside the dashed box to outside the dashed box are the model's calculation outputs.

[0022] like Figure 3 As shown, the input parameters for solving the compressor model include engine speed; the input parameters for solving the combustion chamber model include combustion chamber parameters; and the input parameters for solving the turbine model include turbine throat area. When simulating a high-pressure charging system, the input parameters include charging parameters. The output data of the whole-engine surge model can include engine flow rates such as inlet flow rate. Based on the output data, the engine surge boundary and the dynamic characteristics of engine surge can be obtained. Combustion chamber parameters include combustion heat release, fuel flow rate, and may also include combustion chamber volume, combustion chamber cross-sectional area, combustion chamber length, etc. Charging parameters may include any one or more of the following: charging position, charging pressure, charging orifice diameter, number of charging orifices, and charging time. The above parameters are merely illustrative; the model's input parameters are not limited to these. For example, the input parameters for the compressor model also include the point cloud of each stage of the compressor blades, and the profiles of the compressor casing and hub surfaces.

[0023] This embodiment constructs a three-dimensional volumetric force model for the compressor, which has a three-dimensional computational domain (also known as a fluid computational domain or solution domain). Multiple grid points are set in both the blade region and the non-blade region within the computational domain. When simulating the compressor by solving the compressor model, the flow parameters of these grid points are iteratively calculated according to the set algorithm, initial field, and iteration step size. The flow parameters of the grid points can include any one or more of the following: airflow velocity, flow direction velocity, gas static density, gas static pressure, gas static temperature, total temperature, total pressure, pressure ratio, and airflow angle. Figure 4The figure shows a partial schematic diagram of the computational domain 21 of the compressor model in this embodiment. As shown, the boundaries of the computational domain 21 include the inlet boundary 11, the outlet boundary 21, the hub wall 13, the casing wall 15, etc., and also include the charging boundary 19 set by the gas-suction system. The outlet external environment of the compressor model computational domain (i.e., the outlet external environment of the compressor model) 21 is coupled with the inlet external environment of the combustion chamber model computational domain (i.e., the inlet boundary of the combustion chamber model). The combustion chamber model and the turbine model can be solved coupled in the outlet boundary conditions of the compressor model.

[0024] Figure 4 The compressor computational domain shown is a full three-dimensional computational domain, divided into inner nodes and outer nodes. Inner nodes are solved using a three-dimensional volumetric force model, while outer nodes are solved in conjunction with boundary conditions. Some outer nodes are solved using traditional boundary conditions. For example, the inlet boundary uses a recirculation boundary condition: when fluid flows in, the given ambient temperature and pressure are the total temperature and total pressure at the boundary; when fluid flows out, the given ambient pressure is the static pressure at the boundary. The hub surface and casing surface use adiabatic slip boundary conditions: the temperature gradient and tangential velocity gradient at the boundary are zero. The left and right boundaries use periodic boundary conditions: the parameter values ​​at corresponding points on the left and right boundaries are the same.

[0025] In this embodiment, the computational domain of the combustion chamber model is one-dimensional, consisting of multiple nodes lying on the same straight line, including one node at the inlet boundary and one node at the outlet boundary. When simulating the combustion chamber by solving the combustion chamber model, the flow parameters of these nodes are iteratively calculated according to the set algorithm, initial field, and iteration step size. In this embodiment, the iteration step size when solving the compressor model can be an integer multiple of the iteration step size when solving the combustion chamber model.

[0026] In this embodiment, the high-pressure gas-filled gas-filling system is simulated using inflation boundary conditions. The inflation port is simulated by defining a boundary surface (i.e., inflation boundary) in the compressor model computational domain at the casing position corresponding to the actual test. Considering that in the test, to ensure the stability of the inflation pressure (i.e., one control valve opening corresponds to one inflation pressure), this embodiment uses multiple high-pressure gas cylinders connected in parallel. Therefore, the gas source can be approximated as a constant total temperature and total pressure state, and the boundary condition corresponding to the grid block is defined as the total temperature and total pressure boundary condition. The change in valve opening is realized in the model through the time-varying total pressure. In the test, since the gas source temperature is close to the room temperature, the heat exchange of the gas in the inflation pipeline to the outside is basically negligible, that is, the wall of the inflation pipeline is approximately adiabatic. Therefore, the total temperature in the boundary condition is set as a constant, that is, the boundary condition with constant total pressure and constant total temperature is adopted. This disclosure discloses a high-pressure inhalation system for inhalation achieved through inflation boundary conditions. It can provide a variety of easily adjustable inhalation parameters, including inflation position, inflation pressure, inflation orifice diameter, number of inflation orifices, and inflation time, enabling comprehensive and systematic simulation evaluation.

[0027] This disclosure employs different dimensional models for different engine components: a three-dimensional volumetric force model is used for the compressor component; a one-dimensional model with coupled cavity exothermic effects is used for the combustion chamber component; a zero-dimensional model with coupled throat blockage effects is used for the turbine component, and the critical equation for turbine throat blockage is used for calculation, ignoring the changes in the actual characteristics of the turbine and its downstream components; the model of the surge system is implemented in the form of the charging boundary conditions of the compressor model. The simulation method of this disclosure can simulate the process of a whole-engine surge test using high-pressure gas charging, obtain the whole-engine surge boundary, and has high surge prediction accuracy and computational efficiency, making it an effective means for the design and evaluation of actual whole-engine surge test parameters.

[0028] In an exemplary embodiment of this disclosure, the simulation of the compressor, combustion chamber, turbine, and exhaust system includes: setting the charging boundary conditions of the compressor model, and iteratively calculating the computational domain of the compressor model and the computational domain of the combustion chamber model according to a set time step; wherein, one iteration includes: Based on the initial field or the result of the previous iteration, the computational domain of the compressor model is iterated once, and the first parameter of the outlet boundary of the compressor model is passed to the inlet boundary of the combustion chamber model. The flow parameters of the inlet boundary of the combustion chamber model are updated according to the first parameter, and the computational domain of the combustion chamber model is iterated k times. The second parameter of the inlet boundary of the combustion chamber model is then passed to the outlet boundary of the compressor model. The flow parameters at the outlet boundary of the compressor model are updated based on the second parameter for the next iteration calculation of the computational domain of the compressor model. The step size for iterative calculation of the computational domain of the compressor model is K times the step size for iterative calculation of the computational domain of the combustion chamber model, where K is a positive integer.

[0029] In one example of this embodiment, the first parameter includes total temperature, total pressure, static pressure, and flow rate; updating the flow parameters at the inlet boundary of the combustion chamber model based on the first parameter includes: When the current flow is in a co-current state, the flow parameters at the inlet boundary of the combustion chamber model are updated based on the total temperature, total pressure, and flow rate at the outlet boundary of the compressor model. When the current state is reflux, the flow parameters of the inlet boundary of the combustion chamber model are updated according to the static pressure at the outlet boundary of the compressor model.

[0030] In one example of this embodiment, the second parameter includes total temperature, total pressure, and static pressure; updating the flow parameters at the outlet boundary of the compressor model based on the second parameter includes: When the current flow is in a co-current state, the flow parameters at the outlet boundary of the compressor model are updated based on the static pressure at the inlet boundary of the combustion chamber model. When the current state is recirculation, the flow parameters at the outlet boundary of the compressor model are updated based on the total temperature and total pressure at the inlet boundary of the combustion chamber model.

[0031] In this embodiment, the outlet boundary of the compressor model is coupled with the inlet boundary of the combustion chamber model as the interface for data transmission between the compressor model and the combustion chamber model, and the charging boundary condition of the compressor model is used as the interface for data transmission between the compressor model and the gas-suction system model.

[0032] like Figure 5A and Figure 5B As shown in the figure, it is marked as 0 The line is used to represent the current time step. , Δt 3 It is the iteration step size when performing iterative calculations on the computational domain of the compressor model. Δt 1 It is the iteration step size when performing iterative calculations on the computational domain of the combustion chamber model. Δt 3 =k Δt 1 In the illustrated example, k ⩾2, and the specific value can be set as needed to meet the requirements of synchronous calculation of the two models. As shown in the figure, the first parameter of the compressor model's outlet boundary obtained at the current time step needs to be passed to the combustion chamber model's inlet boundary. The black dot marked 1 in the figure represents a node at the combustion chamber model's inlet boundary, and the black dot marked 2 represents a node adjacent to that node at the inlet boundary.

[0033] Figure 5A This indicates that when the airflow is in a co-current state (from the compressor to the combustion chamber), the combustion chamber model utilizes the transferred total temperature. T t Total pressure p t and traffic The flow parameters at the nodes of the combustion chamber model inlet boundary are updated, such as according to... T t , p t and The static pressure is obtained by conversion. , static temperature T and flow velocity v And it is used as the updated parameter for that node. Figure 5BThis indicates that when the airflow is in a recirculation state (flowing from the combustion chamber to the compressor), the transmitted static pressure is utilized. Update the static pressure of the nodes at the inlet boundary of the combustion chamber model.

[0034] In this embodiment, when transmitting the first parameter, parameters such as total temperature, total pressure, static pressure, and flow rate at the compressor model outlet boundary can be transmitted to the combustion chamber model inlet boundary. The combustion chamber model can determine whether the airflow is in a co-current or re-current state based on the transmitted flow rate (including information on the airflow direction), thereby extracting the corresponding parameters to update the flow parameters of the nodes at the combustion chamber model inlet boundary.

[0035] like Figure 5A and Figure 5B As shown, after updating the flow parameters of the nodes at the inlet boundary of the combustion chamber model according to the first parameter, the computational domain of the combustion chamber model is iterated for k time steps, with a total iteration time of k. Δt 1 Then, the second parameter of the combustion chamber model inlet boundary is passed to the compressor model outlet boundary. This second parameter includes the total temperature, total pressure, and static pressure of the combustion chamber model inlet boundary (i.e., the total temperature, total pressure, and static pressure of the nodes of the combustion chamber model inlet boundary obtained after k iterations). After receiving the second parameter, if the airflow is in a downstream state (still based on the airflow direction calculated in this iteration), the compressor model uses the static pressure... The static pressure of the grid points at the compressor model outlet boundary is updated. If the airflow is in a recirculation state, the corresponding parameters of the grid points at the compressor model outlet boundary are updated based on the static temperature and static pressure calculated from the total temperature and total pressure in the second parameter.

[0036] This embodiment uses bidirectional information transfer between the compressor model and the combustion chamber model to update the flow parameters of the grid points at the compressor model's outlet boundary, and then performs the next iteration calculation on the computational domain of the compressor model based on the updated flow parameters.

[0037] The compressor model is a three-dimensional model, and its outlet boundary in the three-dimensional computational domain can include multiple grid points. The combustion chamber model, on the other hand, is a one-dimensional model, and its inlet boundary in the one-dimensional computational domain has one node. When the first parameter of the compressor model's outlet boundary is passed to the combustion chamber model's inlet boundary, the corresponding parameter values ​​of all grid points on the compressor model's outlet boundary can be averaged and then used to update the parameters of the nodes on the combustion chamber model's inlet boundary. Conversely, when the second parameter of the combustion chamber model's inlet boundary is passed to the compressor model's outlet boundary, the corresponding parameter values ​​of the nodes on the combustion chamber model's inlet boundary can be assigned to each grid point on the compressor model's outlet boundary, thus achieving data conversion between the one-dimensional and three-dimensional computational domains.

[0038] This embodiment uses a method of coupling one-dimensional and three-dimensional models to parameterize the pipeline cavity system downstream of the compressor, which can accurately predict compressor surge.

[0039] In an exemplary embodiment of this disclosure, performing k iterative calculations on the computational domain of the combustion chamber model includes: each time the computational domain of the combustion chamber model is iteratively calculated, for each node in the computational domain of the combustion chamber model, solving the following flow control equations using the method of characteristics: in: It is static pressure; It is the static density; A This refers to the cross-sectional area of ​​the combustion chamber. v The flow velocity in the combustion chamber; x The coordinates represent the length of the combustion chamber; For time; G Friction; a The speed of sound.

[0040] In one example of this embodiment, each time the computational domain of the combustion chamber model is iteratively calculated, the nodes at the outlet boundary of the combustion chamber model (i.e., the nodes at the outlet boundary of the combustion chamber model) are simultaneously solved along with the cavity equation with the heat source, the critical equation for turbine throat blockage, and the flow control equation, wherein: The equation for the cavity with the heat source is as follows: (1) (2) in, The total density of the gas in the combustion chamber. This refers to the total temperature at the turbine inlet. This refers to the total temperature at the compressor outlet. This is the compressor outlet flow rate. This refers to the turbine inlet flow rate; The volume of the combustion chamber; γ represents the heat released during combustion in the combustion chamber; γ is the specific heat capacity of the gas. The critical equation for turbine throat blockage is as follows: (2) in, This refers to the turbine inlet flow rate. This refers to the total temperature at the turbine inlet. This refers to the total pressure at the turbine inlet. This is a constant determined based on the turbine throat area.

[0041] In the above equations, the turbine throat area can be determined by the turbine inlet guide throat area, and the heat release in the combustion chamber can be calculated based on the combustion chamber temperature rise and flow rate. and The represented flows are all quality flows. and The difference is a constant, combustion chamber volume It is known that the heat released during combustion in the combustion chamber Given that the specific heat capacity γ of the gas is known, and the turbine throat area constant is known. The other parameters are known. They are obtained by solving equations (1), (2), and (3) as boundary conditions in conjunction with the flow control equations of the combustion chamber model. In the solution process, other well-known equations, such as the ideal gas law, can also be used.

[0042] In an exemplary embodiment of this disclosure, the compressor model includes multiple grid points respectively set in the blade region and non-blade region of the computational domain; When performing an iterative calculation on the computational domain of the compressor model, the grid points in the blade region are calculated iteratively in the following manner: Based on the flow parameters at the grid point locations obtained in the initial field or the previous iteration, determine the flow conditions at the grid point locations; Based on the flow conditions, determine the ideal velocity field at the grid point location, and construct the volume force vector field at the grid point location based on the ideal velocity field; The flow control equations are solved based on the volume force vector field to obtain the flow parameters at the grid point locations in this iteration.

[0043] In an exemplary embodiment of this disclosure, determining whether the engine has entered surge based on the engine's time-varying data includes: Calculate the compressor surge margin (SMF) using the following formula: in, This represents the inlet flow rate of the compressor. and These are the reference pressure and the reference temperature, respectively; in one example, the reference pressure can be set to the ambient pressure, and the reference temperature can be set to the ambient temperature.

[0044] When the SMF is less than the set threshold, the engine is determined to have entered surge; when the SMF is greater than or equal to the threshold, the engine can be determined to be operating stably, i.e., in a stable operating condition.

[0045] In this embodiment, the surge boundary of the engine is determined based on the SMF parameter. Figure 6An example of using SMF (Self-Surge Flow Metric) to determine the surge boundary is shown. As the surge process progresses, the fluctuation of SMF tends to amplify and eventually drops sharply, falling below the set surge determination threshold. This point is determined to be the surge point, and the inlet flow rate and inlet / outlet pressure ratio corresponding to this point can be marked as the surge boundary point of the engine.

[0046] Surge detection can be performed in different ways. In another embodiment, a different method is used for surge detection. Determining whether the engine has entered surge based on the engine's time-varying data includes: if the curves of the compressor's inlet flow rate and inlet / outlet pressure ratio changing with time in the simulation results form a surge loop, then the engine is determined to have entered surge.

[0047] Figure 6 This paper presents an example of surge dynamic characteristics obtained through simulation based on an engine model. The figure shows the surge dynamic characteristics under different combinations of inflation parameters and the surge point determined by SMF. Each combination of inflation parameters corresponds to a curve in the figure.

[0048] In an exemplary embodiment of this disclosure, the compressor itself is modeled using a three-dimensional volumetric force model. This three-dimensional volumetric force model addresses compressor surge by employing a real-time partitioning approach based on local flow parameters, which can simulate the evolution of the surge recirculation region to the greatest extent possible, thereby completely simulating the entire process of the compressor from steady state to surge instability. This three-dimensional volumetric force model can use the three-dimensional volumetric force model and solution method disclosed in CN114662218A (titled: Turbine Simulation, Instability Prediction Method and Device Based on Volumetric Force Model). The turbine can be a compressor. When modeling the compressor based on the three-dimensional volumetric force model, multiple grid points are set in both the blade region and the non-blade region of the compressor's computational domain.

[0049] When simulating a three-dimensional volumetric force model of a compressor, the point cloud data of the compressor impeller and diffuser blades, the profile data of the compressor hub and casing surfaces, and the engine speed (also known as the compressor operating speed) are used as inputs for preprocessing, including mesh generation, calculation of mesh geometry, calculation of blade geometry, and calculation of the initial field (such as p, T, U). Then, calculation parameters, such as the Corange number, engine speed, and boundary conditions, are set. Before iterative calculations on the mesh points in the computational domain, the boundary conditions of the computational domain need to be set. After each iterative calculation, the relevant parameters of the set boundary conditions can be updated. The boundaries of the computational domain include the inlet boundary, outlet boundary, hub wall, and casing wall. Specifically, when simulating surge conditions, the inlet boundary conditions are selected as total temperature and total pressure conditions in the downstream flow and static pressure conditions in the reflow flow, while the outlet boundary conditions are determined through a coupled combustion chamber model.

[0050] After setting the calculation parameters, the finite volume method can be used to solve the three-dimensional volume force model. Specifically, based on the input and boundary conditions, the flow parameters at the grid points in the computational domain can be iteratively calculated step by step according to the set iteration step size (i.e., the time interval between the current iteration and the next iteration). The blade region is the domain of volume force action; during step-by-step iterative calculation, it is necessary to construct the volume force vector field at the grid point locations in the blade region to serve as the volume force source term in the flow control equations. The non-blade region uses the same control equations, but the volume force source term is 0, and no volume force solution is required.

[0051] Iterative calculations based on grid points in the blade region can include: Step 1: Determine the flow condition at the grid point location based on the flow parameters obtained in the initial field or the previous iteration. Step 2: Determine the ideal velocity field at the grid point location based on the flow conditions, and construct the volume force vector field at the grid point location based on the ideal velocity field; Step 3: Solve the flow control equations based on the volume force vector field to obtain the flow parameters at the grid point locations in this iteration, such as one or more of the following flow parameters: airflow velocity, flow direction velocity, gas static density, gas static pressure, gas static temperature, pressure ratio, airflow angle, etc.

[0052] In one example of this embodiment, before iteratively calculating the flow parameters in the computational domain according to a set time step, the method further includes: setting boundary conditions for grid points on the boundary of the computational domain, and updating the set boundary conditions after each iterative calculation step is completed; wherein, the boundary conditions include inlet boundary conditions and outlet boundary conditions, the inlet boundary conditions are selected as total temperature and total pressure conditions in the downstream flow and as static pressure conditions in the reflow flow, and for the outlet boundary, the boundary conditions of the grid points on the outlet boundary of the computational domain are updated by bidirectional information transfer between the compressor model and the combustion chamber model.

[0053] In one example of this embodiment, the flow control equations are solved based on the volume force vector field, and the flow parameters at the grid point locations in this iteration are obtained based on the solution results, including: The flow control equations are discretized based on grid points in the computational domain, and then numerically solved. The flow control equations include the following equations: in, For airflow velocity, The static density of the gas. For static gas pressure, h t The total enthalpy of the gas. For time, The entrainment speed generated by the rotation of the compressor. The volume force acting on a unit mass of fluid. It is a blocking factor.

[0054] The aforementioned flow control equations are unsteady Euler equations with source terms in an absolute coordinate system, including the mass conservation equation, momentum conservation equation, and energy conservation equation. The physical quantities (i.e., flow parameters) in the flow control equations for a grid point are represented by the physical quantities of the grid point and its surrounding grid points at the previous time step (previous iteration) and at the current time step (this iteration). Therefore, the original control equations can be expressed as the relationship between the physical quantities at each discrete point.

[0055] The above governing equations can be combined with the ideal gas law. p = ρRT The static temperature of the gas is obtained by solving the following formula for calculating the total enthalpy of the gas. T : in, R It is a constant. c p This is the specific heat capacity of the gas at constant pressure.

[0056] In this paper, the parameters and variables in the formulas used to calculate the flow parameters at the grid point location all refer to the parameters and variables at that grid point.

[0057] In another example of this embodiment, the third equation of the above flow control equation set can be replaced by the following equation: in, The total energy is represented by the parameter 't', and the meanings of the other parameters are the same as those in the flow control equations.

[0058] In this embodiment, the volume force experienced by a unit mass of fluid is... It consists of two parts: deflection force and loss of power The volume force vector field at the grid point location is constructed based on the ideal velocity field, including: calculating the deflection force component and loss force component of the volume force at the grid point location based on the ideal velocity direction at the grid point location, and obtaining the volume force at the grid point location based on the deflection force component and loss force component; wherein, when the grid point is located in the downstream region, the direction of the volume force at the grid point location is determined by the directions of the deflection force component and the loss force component; when the grid point is located in the recirculation region, the direction of the volume force at the grid point location is always the blade normal.

[0059] For example, the value of the deflection force component at this grid point location can be calculated using the following formula: in, The value of the deflection force component. This is the proportional gain coefficient. The static density of the airflow The relative velocity of the airflow. for The component along the direction of airflow. W n for The components of the intersection line between the plane perpendicular to the ideal velocity direction and the S1 flow surface. R , s and β These represent the radius of curvature, pitch, and blade angle of the grid points on the blade, respectively. When the grid point is located in the downstream region, the direction of the deflection force component is perpendicular to... .

[0060] For example, the value of the loss force component at this grid point location can be calculated using the following formula: in, For the value of the loss force component, and It is a coefficient (loss coefficient) calculated based on the angle of attack of the airflow. The static density of the airflow The entrainment speed generated by the rotation of the compressor. For airflow static pressure, For airflow velocity, The relative velocity of the airflow is given by m, where m is the direction of flow. When the grid point is located in the downstream region, the direction of the loss force component is... parallel.

[0061] One or more grid points (also called grid blocks) are selected from the grid points set in the computational domain of the above-mentioned volumetric force model as monitoring points. Based on the iteration results, the changes in flow parameters at these monitoring points over time can be determined, and surge prediction can be performed. In this embodiment, the grid points based on the compressor inlet boundary are used as monitoring points to monitor their flow rate, thereby determining the changes in compressor inlet flow rate over time, and using this information for surge prediction (i.e., surge determination).

[0062] One embodiment of this disclosure also provides a simulation device for engine surge testing, such as... Figure 2 As shown, it includes a processor 60 and a memory 50 storing a computer program, wherein the processor 60 executes the computer program to implement the method as described in any embodiment of this disclosure.

[0063] The processor in this disclosure can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), a microprocessor, etc., or other conventional processors. The processor can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an off-the-shelf programmable gate array (FPGA), discrete logic or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above devices. That is, the processor in the above embodiments can be any processing device or combination of devices that implements the methods, steps, and logic block diagrams disclosed in the embodiments of this invention. If this disclosure is implemented in part in software, instructions for software can be stored in a suitable non-volatile computer-readable storage medium, and one or more processors can be used to execute the instructions in hardware to implement the methods of this disclosure.

[0064] The simulation method for engine surge testing disclosed in this embodiment provides a numerical simulation method for high-pressure surge testing of aero-engines. It can reproduce the surge process on a real test bench through numerical simulation and obtain the surge boundary of the entire engine. Furthermore, the high-pressure charging system simulation method proposed in this embodiment can conveniently evaluate the impact of different charging parameters on the surge test results, providing guidance for the design of actual engine surge test parameters, and has the potential to eventually partially replace the engine surge test. The position, number, and size of the charging boundary can be freely adjusted according to the actual test requirements and the allowable range of variation. Figure 3 Examples of several different inflation positions and the number of inflation holes are given. For each inflation boundary, the total temperature and total pressure can be given separately. The total temperature is the gas source temperature, usually room temperature; the total pressure is a time-varying value, which varies with time according to the actual inflation rate and the magnitude of the gas source pressure.

[0065] The numerical simulation method for engine surge testing provided in this disclosure employs different dimensional models for different engine components and the charging surge system: a three-dimensional volumetric force model is used for the compressor component; a one-dimensional model with coupled cavity exothermic effects is used for the combustion chamber component; a zero-dimensional model with coupled throat blockage effects is used for the turbine component; and the charging system uses time-varying total pressure and constant total temperature charging boundary conditions. Using this disclosure, the process of conducting a whole-engine surge test using high-pressure charging can be simulated, and the whole-engine surge boundary can be obtained, making it an effective means for designing and evaluating parameters for actual whole-engine surge tests.

[0066] In one or more exemplary embodiments of this disclosure, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality may be stored as one or more instructions or code on or transmitted via a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may comprise a computer-readable storage medium corresponding to a tangible medium, such as a data storage medium, or a communication medium comprising any medium facilitating the transfer of a computer program from one place to another, such as according to a communication protocol. In this manner, a computer-readable medium may generally correspond to a non-transitory tangible computer-readable storage medium or a communication medium, such as a signal or carrier wave. A data storage medium may be any available medium accessible by one or more computers or one or more processors to retrieve instructions, code, and / or data structures for implementing the techniques described in this disclosure. A computer program product may comprise a computer-readable medium.

[0067] For example, and not as a limitation, such computer-readable storage media may include RAM, ROM, EEPROM, CD-ROM or other optical disc storage devices, magnetic disk storage devices or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and is accessible by a computer. Furthermore, any connection may also be referred to as a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. However, it should be understood that computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transient media, but rather refer to non-transient tangible storage media. As used herein, disks and optical discs include compact optical discs (CDs), laser discs, optical discs, digital versatile optical discs (DVDs), floppy disks, or Blu-ray discs, where disks typically reproduce data magnetically, while optical discs use lasers to reproduce data optically. The above combinations should also be included within the scope of computer-readable media.

[0068] Instructions can be executed by one or more processors, such as one or more digital signal processors (DSPs), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the term "processor" as used herein can refer to any of the above-described structures or any other structures suitable for implementing the techniques described herein. Additionally, in some aspects, the functionality described herein can be provided within dedicated hardware and / or software modules configured for encoding and decoding, or incorporated into combined codecs. Furthermore, the techniques can be fully implemented in one or more circuit or logic elements.

[0069] The technical solutions of the embodiments of this disclosure can be implemented in a wide variety of devices or equipment, including wireless mobile phones, integrated circuits (ICs), or a set of ICs (e.g., chipsets). Various components, modules, or units are described in the embodiments of this disclosure to emphasize functional aspects of a device configured to perform the described techniques, but they do not necessarily need to be implemented through different hardware units. Rather, as described above, various units can be combined in codec hardware units or provided by a collection of interoperable hardware units (including one or more processors as described above) combined with suitable software and / or firmware.

Claims

1. A simulation method for engine power surge test, comprising: Models were created for the engine's compressor, combustion chamber, turbine, and exhaust system. The compressor model established for the compressor is a three-dimensional volumetric force model capable of simulating surge. The combustion chamber model established for the combustion chamber is a one-dimensional model of coupled cavity exothermic effects; The turbine model established for the turbine is a zero-dimensional model coupled with the throat blockage effect; The breathing system model established for the breathing system simulates the high-pressure breathing system in the form of the inflation boundary conditions of the compressor model; The inlet boundary of the combustion chamber model is the outlet boundary of the compressor model, and the outlet boundary of the combustion chamber model is the inlet of the turbine model. The combustion chamber model includes the cavity equations of the combustion chamber with a heat source, and the outlet boundary of the combustion chamber model contains the critical equations for turbine throat blockage in the turbine model. The turbine model is solved in conjunction with the outlet boundary conditions of the combustion chamber model. The process of performing a full-engine surge simulation includes: setting the input parameters of the model, running the model to simulate the compressor, combustion chamber, turbine and surge system, and obtaining data on engine changes over time. The breathing system model simulates the inflation port for high-pressure gas by setting one or more inflation boundaries corresponding to the compressor casing position on the computational domain of the compressor model. The inflation boundary conditions are set to use constant total temperature and time-varying total pressure conditions. The engine is determined to have entered surge mode based on the engine's data over time.

2. The method as described in claim 1, characterized in that: The input parameters for the compressor model include engine speed; The input parameters of the combustion chamber model include the fuel flow rate and the heat released during combustion. The input parameters for the turbine model include the turbine throat area; The input parameters of the breathing system model include any one or more of the following parameters: inflation position, inflation pressure, inflation orifice diameter, number of inflation orifices, and inflation time.

3. The method as described in claim 1, characterized in that: The simulation of the compressor, combustion chamber, turbine, and exhaust system includes: setting the charging boundary conditions of the compressor model, and iteratively calculating the computational domain of the compressor model and the computational domain of the combustion chamber model according to a set time step; One iteration includes: Based on the initial field or the result of the previous iteration, the computational domain of the compressor model is iterated once, and the first parameter of the outlet boundary of the compressor model is passed to the inlet boundary of the combustion chamber model. The flow parameters of the inlet boundary of the combustion chamber model are updated according to the first parameter, and the computational domain of the combustion chamber model is iterated k times. The second parameter of the inlet boundary of the combustion chamber model is then passed to the outlet boundary of the compressor model. The flow parameters at the outlet boundary of the compressor model are updated based on the second parameter for the next iteration calculation of the computational domain of the compressor model. The step size for iterative calculation of the computational domain of the compressor model is K times the step size for iterative calculation of the computational domain of the combustion chamber model, where K is a positive integer.

4. The method as described in claim 3, characterized in that: The first parameter includes total temperature, total pressure, static pressure, and flow rate; updating the flow parameters at the inlet boundary of the combustion chamber model based on the first parameter includes: When the current flow is in a co-current state, the flow parameters at the inlet boundary of the combustion chamber model are updated based on the total temperature, total pressure, and flow rate at the outlet boundary of the compressor model. When the current state is reflux, the flow parameters of the inlet boundary of the combustion chamber model are updated according to the static pressure at the outlet boundary of the compressor model.

5. The method as described in claim 3, characterized in that: The second parameter includes total temperature, total pressure, and static pressure; updating the flow parameters at the outlet boundary of the compressor model based on the second parameter includes: When the current flow is in a co-current state, the flow parameters at the outlet boundary of the compressor model are updated based on the static pressure at the inlet boundary of the combustion chamber model. When the current state is recirculation, the flow parameters at the outlet boundary of the compressor model are updated based on the total temperature and total pressure at the inlet boundary of the combustion chamber model.

6. The method as described in claim 3, characterized in that: The computational domain of the combustion chamber model is subjected to k iterations, including: for each node in the computational domain of the combustion chamber model during each iteration, the following flow control equations are solved using the method of characteristics: in: It is static pressure; It is the static density; A This refers to the cross-sectional area of ​​the combustion chamber. v The flow velocity in the combustion chamber; x The coordinates represent the length of the combustion chamber; For time; G Friction; a The speed of sound.

7. The method as described in claim 6, characterized in that: Each time the computational domain of the combustion chamber model is iterated, the nodes at the outlet boundary of the computational domain of the combustion chamber model are also solved simultaneously with the equations for the heat source cavity, the critical equation for turbine throat blockage, and the flow control equations, where: The equation for the cavity with the heat source is as follows: in, The total density of the gas in the combustion chamber. This refers to the total temperature at the turbine inlet. This refers to the total temperature at the compressor outlet. This is the compressor outlet flow rate. This refers to the turbine inlet flow rate; The volume of the combustion chamber; γ represents the heat released during combustion in the combustion chamber; γ is the specific heat capacity of the gas. The critical equation for turbine throat blockage is as follows: in, This refers to the turbine inlet flow rate. This refers to the total temperature at the turbine inlet. This refers to the total pressure at the turbine inlet. This is a constant determined based on the turbine throat area.

8. The method as described in claim 3, characterized in that: The compressor model includes multiple grid points set in both the blade region and non-blade region of the computational domain; when performing an iterative calculation on the computational domain of the compressor model, the grid points in the blade region are iteratively calculated in the following manner: Based on the flow parameters at the grid point locations obtained in the initial field or the previous iteration, determine the flow conditions at the grid point locations; Based on the flow conditions, determine the ideal velocity field at the grid point location, and construct the volume force vector field at the grid point location based on the ideal velocity field; The flow control equations are solved based on the volume force vector field to obtain the flow parameters at the grid point locations in this iteration.

9. The method as described in claim 1, characterized in that: The step of determining whether the engine has entered surge based on the engine's time-varying data includes: Calculate the compressor surge margin (SMF) using the following formula: When the SMF is less than the set threshold, the engine is determined to have entered surge. in, This represents the inlet flow rate of the compressor. and These are the reference pressure and the reference temperature, respectively.

10. A simulation device for an engine breathing test, comprising a processor and a memory storing a computer program, wherein, When the processor executes the computer program, it implements the simulation method for engine breathing test as described in any one of claims 1 to 9.

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