An engine modeling method based on parallel compressor theory for inlet distortion

Abstract

The application relates to a modeling method of an engine with inlet distortion based on parallel compressor theory, comprising an air path model of the engine, a matching method of the air path model and application. On the basis of an original double-shaft split-fan engine model, three calling models of a distortion splitter model, a parallel fan model and a mixing chamber model are added, and then a new air path model matching of the engine is carried out. The application realizes accurate control of an airplane under special working conditions. The application is based on a parallel compressor model, takes a double-shaft split-fan engine with a large bypass ratio as a research object, and establishes an aero-engine simulation model considering inlet distortion.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of engine gas path model and matching method of gas path model, and relates to a modeling method of engine with inlet distortion based on parallel compressor theory, including engine gas path model, matching method of gas path model and application. BACKGROUND

[0002] The aerodynamic stability of an aero-engine is a key indicator for evaluating the performance of the engine. The engine must be able to resist the interference of the stability reduction factor and ensure sufficient available stability margin within the entire flight envelope, in addition to having superior performance in key design states. The core lies in the stability of the fan or compressor, and the inlet distortion is an important factor leading to the deterioration of the compressor stability and is also the main research content in the process of evaluating the compressor stability.

[0003] The inlet distortion is one of the external factors affecting the stability of the engine, which can cause a significant decline in the performance of the compressor. The pressure distortion, temperature distortion and rotational distortion all belong to the category of inlet distortion. From the perspective of flow mechanism, the non-uniformity of the inlet pressure, temperature and rotational flow actually changes the time and spatial distribution of the air density, thereby affecting the stability of the engine. The temperature distortion can sharply change the stable operating line of the engine, resulting in a reduction in the stable operating range. At the same time, the total pressure distortion and rotational distortion of the inlet can also cause a decline in the performance and stability margin of the compressor, and in severe cases, can even lead to rotational stall, surge and even shutdown, causing serious harm to the engine.

[0004] The numerical calculation model for the influence of the inlet distortion on the aerodynamic performance of the compressor includes the parallel compressor model, the half-disk model and the body force model. The disk model cannot analyze the influence of the inlet distortion on the detailed flow field inside the blade passage, and the aerodynamic instability of the compressor is usually caused by the tip leakage flow and the separation of the boundary layer, so there may be certain errors in predicting the stability boundary. The method for obtaining the body force in the three-dimensional body force model has a direct impact on the calculation accuracy, and the force is usually obtained by CFD calculation or experiment under uniform inlet conditions, so its accuracy has not been guaranteed.

[0005] The parallel compressor model adopted in the present application is relatively simple and fast in calculation, and has a high prediction accuracy with little error in the case of rich experience. In the parallel compressor model, it is generally believed that the radial distortion has little influence on the stability of the compressor, so the calculation model only considers the influence of the steady circumferential distortion, including the total pressure distortion and the total temperature distortion, that is, it is assumed that the airflow of the fan is uniformly distributed along the radial direction. The model only needs to divide the inlet of the annular passage of the compressor into multiple sectors along the circumference, and assumes that the airflow parameters are uniformly distributed along the circumference in each sector. However, the model still cannot correctly simulate the circumferential mixing of the flow in the compressor and predict the propagation of the distorted inlet in the passage of the compressor.

[0006] At present, the research on inlet distortion in China mainly focuses on experimental methods, but this method has high requirements for equipment and technology, long test cycle and high cost. On the other hand, numerical simulation is also an important research means. However, due to the complexity of the causes, propagation methods and influence mechanisms of engine inlet distortion, most of the current research on aero-engine inlet distortion still relies on experimental methods, and the potential of numerical simulation technology in this field has not been fully developed, so the simulation method combining research and computer simulation technology and the evaluation method have important significance.

[0007] In addition, the research on inlet distortion in China is still insufficient, and the flow mechanism research on such complex problems is still in the initial stage and needs to be further enriched and improved. By analyzing the transmission process of inlet distortion in the compressor, the stability of each stage of the compressor can be quantitatively evaluated, and only by deeply understanding the flow field structure and distortion transmission process of the multi-stage compressor under inlet distortion, the inlet distortion of the compressor can be controlled and utilized. SUMMARY

[0008] Technical problems to be solved

[0009] In order to avoid the shortcomings of the prior art, the present application provides a modeling method of an engine with inlet distortion based on parallel compressor theory, which includes an engine gas path model, a matching method of the gas path model and application. The present application realizes accurate control of an aircraft under special conditions, and establishes an aero-engine simulation model considering inlet distortion based on a parallel compressor model and taking a high-bypass-ratio dual-axial split-annular turbofan engine as the research object.

[0010] Technical scheme

[0011] A gas path model of an engine with inlet distortion based on parallel compressor theory, comprising an inlet duct model, a plurality of compressor models, a plurality of turbine models, a combustion chamber model, a nozzle model and channel losses between the models; characterized in that it further comprises a distortion splitter model, a parallel fan model and a mixing chamber model; the combination of the engine gas path model along the airflow path is: the inlet duct model, the distortion splitter model, the parallel fan model, the mixing chamber model, the inner-outer channel splitter model, the low-pressure compressor model and the high-pressure compressor model in series, the combustion chamber model, the high-pressure turbine model and the low-pressure turbine model in series, and the nozzle model; the front end of the high-pressure compressor model, the low-pressure compressor model, the high-pressure turbine model, the low-pressure turbine model and the nozzle model is a channel loss; the distortion splitter model divides the airflow at the fan inlet into two parallel airflows, and each airflow model combination is a distortion splitter model; the parallel fan model is two distortion-free sub-fans corresponding to the parallel airflows of the distortion splitter model and distortion sub-fan parallel fan model combination; the mixing chamber model is located at the parallel fan model outlet, combining two air flows into one, and then dividing into two, one into the outer duct, and the other into the low pressure compressor; the engine model with inlet distortion is recombined with the engine air path model, and the engine is matched with the air path model, when the inlet air flow is distorted, the distorted flow field is divided into zones in the circumferential direction by introducing the distortion distributor model, the parallel fan model and the mixing chamber model, the non-distorted sub-fan and the distorted sub-fan are calculated independently.

[0012] The parallel fan model is used to describe the non-distorted sub-fan and the distorted sub-fan , the inlet air flow channels of which are respectively matched with the outlet of the two fan-shaped areas of the distortion distributor model, and the inlet air flow parameters are respectively equal to the outlet air flow parameters of the two air flow channels of the distortion distributor model.

[0013] The total temperature distortion index of the distortion distributor model is TP = ， The total pressure distortion index is PP = ; the air flow parameters of the two fan-shaped areas in the model are distributed as the inlet air flow parameters of the two fan-shaped areas of the distortion distributor model being equal to the outlet air flow parameters of the inlet duct model, including: the flow rate , total temperature , total pressure , total enthalpy and oil-gas ratio of the inlet duct outlet; the two fan-shaped area outlets are divided into the outlet corresponding to the non-distorted sub-fan and the outlet corresponding to the distorted sub-fan , wherein: The air flow parameters of the outlet corresponding to the non-distorted sub-fan are: outlet flow rate , temperature , pressure , enthalpy , and oil-gas ratio equal to the inlet values of the model; The outlet flow rate of the outlet corresponding to the distorted sub-fan , the outlet total temperature · ( TP+ 1 ), the outlet total pressure · (PP+1 ), Total enthalpy , Total gas ratio Equal to the model inlet value.

[0014] The two inlet airflow parameters of the parallel fan model are equal to the corresponding outlet airflow parameters of the distortion splitter model.

[0015] The two airflows of the mixing chamber model flow in parallel and are uniformly distributed at the inlet cross section respectively; the static pressure of the two airflows is equal when entering the mixing chamber, that is, ; without considering the heat loss in mixing, the outlet airflow parameter is uniformly distributed; the two mixing chambers in the mixing chamber model are equal cross-section pipes.

[0016] The outlet airflow of the mixing chamber model is distributed according to the ratio of the inner and outer ducts, and then is divided into two, respectively entering the inner and outer ducts; the mixing chamber model includes the energy continuity equation, the momentum balance equation of the inlet and outlet airflows of the mixing chamber model, and the flow continuity equation of the inlet and outlet airflows of the mixing chamber model.

[0017] The energy continuity equation is: · + · = ·

[0018] The momentum balance equation of the inlet and outlet airflows of the mixing chamber model is:

[0019] + = ( + )

[0020] The flow continuity equation of the inlet and outlet airflows of the mixing chamber model is:

[0021] + = ( + )

[0022] Wherein, each parameter is: undistorted sub-fan Outlet cross-section flow , total temperature , total pressure , static pressure , specific enthalpy ,area speed coefficient Fan with aberration Flow rate at the outlet section Total temperature Total pressure static pressure enthalpy ,area speed coefficient Flow rate at the outlet section of the mixing chamber model Total temperature Total pressure enthalpy speed coefficient .

[0023] A matching method for the air path model of an engine with intake distortion based on parallel compressor theory, characterized in that: during matching, trial parameters are set according to the model settings. x Error test equations are set based on model combinations. y The common working equations that constitute the gas path model matching are:

[0024]

[0025] The test condition is: when x The value makes y All zeros indicate that the engine is operating within a balanced condition;

[0026] Since the number of components in x is greater than the number of components in y, it is necessary to give a certain physical quantity in parameter x and then use the multivariate Newton method to solve it, that is, the Newton-Raphson method to achieve gas path model matching.

[0027] The given parameter x consists of 12 independent variables in the engine model, including the physical speed of the low-pressure rotor. Physical speed of high-voltage rotor , distortion-free sub-fan Pressure ratio function value With a distorted fan Pressure ratio function value Low-pressure compressor pressure ratio function value High-pressure compressor pressure ratio function value High-pressure turbine flow ratio function value Low-pressure turbine flow ratio function value (Fan front) Distortion shunt bypass ratio (After the fan) Inner and outer bypass splitter bypass ratio Inlet airflow rate Main combustion chamber outlet total temperature The corresponding error verification equation y consists of 11 residual equations that satisfy the common working balance condition of the component models: including the low-pressure rotor power balance equation, the high-pressure rotor power balance equation, and the distortion-free sub-fan equation. Inlet flow balance equation, fan with distortion Inlet flow balance equation, low-pressure compressor inlet flow balance equation, high-pressure compressor inlet flow balance equation, high-pressure turbine inlet flow balance equation, low-pressure turbine inlet flow balance equation, inner duct nozzle flow balance equation, outer bypass duct nozzle flow balance equation, mixing chamber inlet static pressure balance equation.

[0028] An application of the air path model of an engine with intake distortion based on the parallel compressor theory is characterized in that: the air path model completed by the matching method is used to perform engine thermodynamic calculations to obtain the engine performance parameters such as thrust and fuel consumption rate, as well as the airflow, total temperature, total pressure, and total enthalpy cross-sectional parameters in the air system.

[0029] Beneficial effects

[0030] This invention proposes a modeling method for engines with inlet distortion based on parallel compressor theory, including an engine airflow model, an airflow model matching method, and its application. Based on the original twin-shaft split-flow turbofan engine model, three additional models are added: a distortion splitter model, a parallel fan model, and a mixing chamber model, thereby performing new airflow model matching for the engine. This invention achieves precise aircraft control under special operating conditions. Based on the parallel compressor model, and taking a high-bypass ratio twin-shaft split-flow turbofan engine as the research object, this invention establishes an aero-engine simulation model considering inlet distortion.

[0031] The aero-engine model based on a parallel compressor and considering intake distortion proposed in this invention has the following advantages:

[0032] 1. Using data from GasTurb reflecting the characteristics of each component, the basic model was extensively trained, enabling accurate simulation of the performance of each component and the entire engine, with reliable calculation accuracy.

[0033] 2. This invention performs numerical calculations on a twin-shaft split-flow turbofan engine under total temperature distortion and total pressure distortion intake conditions. It considers not only the impact of distorted airflow on the intake duct and fan, but also the impact of distorted airflow on the rear components of the entire engine, making the numerical simulation closer to the real operating conditions.

[0034] 3. This invention is beneficial for the research and analysis of the actual working state of a dual-shaft turbofan engine, especially for achieving more precise control of the engine under special conditions such as high angle of attack flight and weapon use, reducing margin waste, and fully tapping the working potential of the turbofan engine. Attached Figure Description

[0035] Figure 1 is the basic component diagram of dual-axial split-fan engine

[0036] Figure 2 is the mathematical model diagram considering inlet distortion

[0037] Figure 3 is the air system cross-section serial number identification diagram of dual-axial split-fan engine considering inlet distortion

[0038] Figure 4 is the engine common working point iteration program block diagram. DETAILED DESCRIPTION

[0039] The application will be further described in conjunction with the embodiments and drawings: the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0040] The application realizes the accurate control of the aircraft in special working conditions, and establishes an aero-engine simulation model considering inlet distortion based on a parallel compressor model and taking a dual-axial split-fan engine with a large bypass ratio as the research object.

[0041] Figure 1 is the basic component diagram of dual-axial split-fan engine, from which it can be seen that after the air flow is sucked into the engine, it first flows through the inlet passage and the fan, and then is discharged by the inner and outer canals, wherein the inner canal is composed of a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and a tail nozzle. The fan, the low-pressure compressor and the low-pressure turbine are connected by a low-pressure shaft; the high-pressure compressor and the high-pressure turbine are connected by a high-pressure shaft; and the high-pressure shaft and the low-pressure shaft are not mechanically connected, but are connected only through the air path.

[0042] Figure 2 is the mathematical model diagram considering inlet distortion: when the inlet air flow is distorted, the non-uniform flow field is circumferentially partitioned by introducing a distortion flow divider model, a parallel fan model and a mixing chamber model, and the distortion sub-fan and the non-distortion sub-fan are calculated independently. In the diagram, TP is the total temperature distortion index, PP is the total pressure distortion index, and the definition formula considers that the temperature and pressure of the distortion area are higher than those of the non-distortion area.

[0043] The invention adopts a component method to carry out numerical simulation, namely, on the basis of known characteristics of each component of the engine, the performance of the entire engine is simulated by accurately simulating the performance of each component of the engine. Compared with the component method simulation of the dual-shaft split-fan engine without considering the intake distortion, the invention has the following innovations: ① the engine air path model along the airflow path is recombined; and ② the selection of the test parameters and the test equation is different.

[0044] The principle of the invention is based on a parallel compressor model, and it is generally believed that the radial distortion has little effect on the stability of the compressor, so the invention only considers the effects of steady-state circumferential total pressure distortion and total temperature distortion, and the fan is divided into two fan-shaped regions according to the inlet circumferential distortion condition, which respectively correspond to the undistorted sub-fan with uniform inflow and the distorted sub-fan with high pressure or high temperature area.

[0045] The following assumptions are made for the above sub-fans: ① the inlet conditions of each sub-fan are different and work independently without exchange of momentum, mass and energy; ② each sub-fan works in parallel and is connected through the outlet boundary condition, i.e. the same outlet static pressure; ③ each sub-fan works according to the fan characteristic line with uniform undistorted inlet; and ④ when the sub-fan working flow reaches the surge flow of the undistorted fan, it is considered that the entire fan reaches the instability point.

[0046] The recombination of the engine air path model considering the intake distortion is described below. The dual-shaft split-fan engine is composed of an inlet duct, a fan, a low-pressure compressor, a high-pressure compressor, a combustion chamber, a high-pressure turbine, a low-pressure turbine and a tail nozzle, and the airflow is divided into two streams at the fan outlet, one of which flows to the core engine and the other of which flows into the outer duct and is finally discharged into the atmosphere. In order to introduce the factor of intake distortion, the fan model is divided into two parts working in parallel, which is equivalent to carrying out another air path splitting and merging before the splitting of the inner and outer ducts. It should be noted that the "air path splitting and merging" referred to here is a mathematical model setting and not a real air path structure.

[0047] Based on this, the modeling method adds three calling models, i.e. a distortion splitter model, a parallel fan model and a mixing chamber model, to the original dual-shaft split-fan engine model, and then matches the new air path model of the engine. After the inlet airflow flows through the inlet duct, the distortion splitter model is called at the fan inlet to form two parallel airflows which enter the corresponding fan sectors, i.e. the undistorted sub-fan and the distorted sub-fan Since there is no exchange of matter or energy between these two airflows, they can still be calculated using existing fan model numerical methods despite their different inlet conditions. In other words, the so-called parallel fan model involves setting different inlet parameters for the two parallel sectors and using the same fan model for each. At the fan outlet section, the mixing chamber model is used to merge the two airflows into one, which is then split into two streams: one enters the bypass duct, and the other enters the low-pressure compressor, each then entering its corresponding engine component.

[0048] It should be noted that the distortion shunt at the fan inlet utilizes the bypass ratio. BPR The concept is used to achieve flow distribution in two sector regions, and based on the total temperature distortion index... TP and total pressure distortion index PP The degree of distortion is defined by the definition.

[0049] To simulate the entire engine using the component method and obtain the engine's performance parameters and parameters of each section, trial parameters are provided for the gas path model matching of this method. If the following 12 parameters are given, the non-design point characteristic calculation of a twin-shaft split-row turbofan engine considering intake distortion can be completed. Therefore, these 12 parameters are called independent variables.

[0050] The parameters to be provided include: physical speed of the low-pressure rotor. Physical speed of high-voltage rotor , distortion-free sub-fan Pressure ratio function value With a distorted fan Pressure ratio function value Low-pressure compressor pressure ratio function value High-pressure compressor pressure ratio function value High-pressure turbine flow ratio function value Low-pressure turbine flow ratio function value (Fan front) Distortion shunt bypass ratio (After the fan) Inner and outer bypass splitter bypass ratio Inlet airflow rate Main combustion chamber outlet total temperature There are a total of 12 trial parameters.

[0051] So how do we correctly select these parameters? It's about ensuring the chosen independent variables meet the balance conditions for the components working together. Based on power balance, flow balance, and pressure balance, we can obtain the following 11 error equations (or verification equations). Therefore, verifying whether the above-mentioned trial parameters are the operating point parameters for the entire engine requires the following residual equations: low-pressure rotor power balance equation, high-pressure rotor power balance equation, and distortion-free sub-fan equation. Inlet flow balance equation, fan with distortion The 11 test equations are: inlet flow balance equation, low pressure compressor inlet flow balance equation, high pressure compressor inlet flow balance equation, high pressure turbine inlet flow balance equation, low pressure turbine inlet flow balance equation, inner bypass duct nozzle flow balance equation, outer bypass duct nozzle flow balance equation, mixed chamber inlet static pressure balance equation.

[0052] Therefore, the common working equation set of the two-axial split-flow turbofan engine considering the inlet distortion can be described as:

[0053]

[0054] wherein y is an 11-element equation set, x has 12 components, if the value of x makes y all zero, it means that the engine working satisfies the balance condition, that is, the value of x at this time is the solution of the common working equation set.

[0055] The common working equation set y has no specific expression, and is composed of all variable specific heat formulas calculated from the atmosphere, inlet duct to the afterburner, and is essentially a multi-element nonlinear equation set, so the multi-element Newton method is used for solving, that is, the Newton-Raphson method.

[0056] Moreover, the error equation has 11 elements, and the independent variable has 12 elements, the equation set is not "closed", that is, it cannot be solved, so an independent variable needs to be determined in advance to make the equation set "closed" and then solve the equation set. The common method is to give the physical speed n of the compressor or the total temperature Tt4 of the turbine inlet, and here I choose to give Tt4, as shown in the following figure.

[0057] The test equation is less than the given parameter, which will lead to infinite solutions of the nonlinear equation set, in order to ensure the stable working of the engine, a change rule of the given parameter needs to be given. In this model, the adjustment rule of const、 const is adopted, wherein is the fuel supply of the main combustion chamber, is the throat area of the afterburner, by giving the fuel supply of the main combustion chamber, the value of one of the given parameters can be obtained by bisection iteration.

[0058] The above steps are called the common working between the models of each component of the engine, also called the matching of the models of each component.

[0059] The above adjustment rule is used to make the test equation equal to the number of test parameters, and then the common working point of the engine can be found, and the steps include: ① give a set of initial values to the remaining 11 test parameters to perform engine thermal calculation, and obtain 11 residuals; ② if the norm of the residual is less than the set error limit, then the test parameters at this time are the common working point parameters of the engine, and then the engine performance parameters and the section parameters can be obtained; ③ if it is greater than the error limit, a small increment is given to the 11 test parameters while keeping the values of the other 10 test parameters unchanged, and 11 times of engine thermal calculation is performed to obtain 11 sets of residuals; ④ construct and solve a linear equation set to calculate a new set of test parameter values until the requirement of step ② is met.

[0060] The specific embodiment provides the following technical scheme, an aero-engine model considering inlet distortion based on a parallel compressor is established, and the model establishment method comprises the following steps:

[0061] Figure 3 is a section serial number identification diagram of a double-shaft split-fan engine air system considering inlet distortion, wherein, Figure 3 (a) is a section serial number identification based on real components, which is only used to provide position information of main air path sections, and cannot give accurate relationship of relative size and position of each component; Figure 3 (b) is a section serial number identification based on a mathematical model, which is used for subsequent detailed description of matching of the air path model considering inlet distortion.

[0062] The section serial numbers of the air system used in the model are as shown in (b), according to the initialization parameters required by each component of the engine given by GasTurb, the calculation of the design point is started after the input is completed. Figure 3

[0063] The inlet flow of the inlet section 1 is given under the given atmospheric conditions, and the air flow parameters of the outlet section 2 of the inlet duct are calculated through the called inlet duct model.

[0064] Because the inlet distortion is considered, the fan inlet two fan-shaped subareas and 1 of the section are obtained through the called distortion splitter model; The inlet flow of the fan section is calculated through the called compressor model to obtain the outlet flow parameters of the fan section; the inlet flow of the fan section is calculated through the called compressor model to obtain the outlet flow parameters of the fan 2 section; and the fan outlet ​2 Two air flows in cross section are calculated by the mixing chamber model with calling. The inlet air flow parameters of the inner and outer bypass splitter are given as follows:

[0065] As shown in Figure 2 , the present application assumes that the inlet air flow of the engine is divided into two parallel air flows at the fan inlet after passing through the inlet duct, and then enters the parallel fan model, i.e. the undistorted sub-fan and the distorted sub-fan . It is considered that there is no exchange of matter and energy between the two air flows, and the two air flows are mixed into one air flow at the fan outlet cross section, and then are divided into two air flows, which enter the outer bypass duct and the low-pressure compressor respectively, and then flow into the next corresponding engine components.

[0066] The following parameters are defined: the flow rate , total temperature , total pressure , total enthalpy and oil-gas ratio of the outlet of the inlet duct; the inlet flow rate , inlet total temperature , inlet total pressure , inlet total enthalpy and inlet oil-gas ratio of the undistorted sub-fan ; the inlet flow rate , inlet total temperature , inlet total pressure , inlet total enthalpy and inlet oil-gas ratio of the distorted sub-fan ; the area ratio of the fan-shaped region of the undistorted sub-fan to the distorted sub-fan , i.e. the bypass ratio of the distortion splitter model , total temperature distortion index TP = ， total pressure distortion index PP = 。

[0067] The inlet air flow parameters of the undistorted sub-fan are

[0068] ;

[0069] ;

[0070] ;

[0071] ;

[0072] ;

[0073] Distorted sub-fan The inlet flow parameters of

[0074] ;

[0075] · ( TP+1 );

[0076] · ( PP+1 );

[0077] ;

[0078] ;

[0079] After obtaining two sets of outlet flow parameters of the distorted splitter model, each sub-fan is assumed to work according to the compressor characteristic line of uniform and undistorted inlet air, and the fan model is independently calculated and then the mixing chamber model is called.

[0080] To express the calculation process of the mixing chamber model, the following parameters are defined: undistorted sub-fan outlet cross-section flow rate total temperature total pressure static pressure specific enthalpy area velocity coefficient distorted sub-fan outlet cross-section flow rate total temperature total pressure static pressure specific enthalpy area velocity coefficient mixing chamber model outlet cross-section flow rate total temperature total pressure specific enthalpy velocity coefficient .

[0081] The following assumptions are made for the calculation of the mixing chamber model: ① two air flows flow in parallel and are uniformly distributed in the inlet cross-section respectively; ② the static pressures of the two air flows are equal when entering the mixing chamber, i.e. ; ③ the heat loss in mixing is not considered, and the outlet air flow parameter distribution is uniform; ④ the mixing chamber is an equal cross-section pipe.

[0082] According to the sub-fan And the fan By writing a continuity equation using the outlet cross-section parameters, the outlet airflow rate of the mixing chamber model can be obtained.

[0083] ;

[0084] The specific enthalpy at the mixing chamber outlet can be obtained from the energy continuity equation.

[0085] · + · = · ;

[0086] Seeking Then, the total temperature of the gas flow at the outlet of the mixing chamber can be obtained iteratively using the bisection method. .

[0087] Next, the areas of the two inlet sectors of the mixing chamber model, i.e., the sub-fans, are calculated. Export area Kazuko Fan Export area The method is as follows:

[0088] (1) Predict a sub-fan Export area Solve for the sub-fan according to the flow continuity equation. velocity coefficient of the outlet airflow ;

[0089] (2) Then the fan outlet static pressure = · Π( );

[0090] (3) According to the definition of bypass ratio in the above distortion shunt model, the sub-fan Export area is / Similarly, we can find the sub-fan. outlet static pressure = · Π( );

[0091] (4) Iterative calculation using the bisection method Until the sub-fan outlet static pressure and sub-fan The outlet static pressure is equal, that is... At this time, the sub-fan Export area Sub-fan Export area = / .

[0092] Repeat the above steps to obtain the sub-fan. And the fan outlet static pressure and ;

[0093] Momentum balance equations of inlet and outlet airflow from the mixing chamber model

[0094] + = ( + )

[0095] Furthermore, the flow continuity equations of the inlet and outlet airflow in the mixing chamber model are derived.

[0096] + = ( + )

[0097] Solving the two equations simultaneously will yield the total outlet pressure of the mixing chamber model. and the outlet airflow velocity coefficient of the mixing chamber model The total temperature of the outlet airflow of the mixing chamber model is then determined through the above steps. Total pressure and traffic Both are available.

[0098] The airflow at the outlet of the mixing chamber model is split into two streams, which enter the inner duct and the outer duct respectively. The flow rate is determined based on the ratio of the inner and outer ducts. The airflow parameters of the inner bypass section 21 and the outer bypass section 13 were calculated using the inner and outer bypass splitter models.

[0099] The airflow parameters of the duct section 16 are calculated by calling the duct loss model for the inlet airflow of the duct section 13, and then the airflow parameters of the duct nozzle section 18 are calculated by calling the nozzle model. The static pressure of section 18 is equal to the static pressure of the inlet airflow.

[0100] The airflow parameters at the inlet section 22 of the low-pressure compressor are calculated by calling the duct loss model, and then the airflow parameters at the outlet section 24 of the low-pressure compressor are calculated by calling the compressor model.

[0101] The airflow parameters at the outlet section 25 of the high-pressure compressor are calculated by calling the duct loss model at the outlet of the low-pressure compressor, and then the airflow parameters at the outlet section 3 of the high-pressure compressor are calculated by calling the compressor model.

[0102] The airflow at the high-pressure compressor outlet is calculated using the combustion chamber model to obtain the airflow parameters at the combustion chamber outlet section 4. Due to the selection of the aforementioned adjustment law, the oil-air ratio (or fuel supply) is a given value.

[0103] The airflow parameters at the high-pressure turbine inlet section 41 are calculated by calling the bypass loss model at the combustion chamber outlet, and then the airflow parameters at the high-pressure turbine outlet section 44 are calculated by calling the turbine model.

[0104] The airflow parameters at the low-pressure turbine inlet section 45 are calculated by calling the bypass loss model at the outlet of the high-pressure turbine. Then, the airflow parameters at the outlet section 5 of the low-pressure turbine are calculated by calling the turbine model. The guide vanes and rotor blades at the inlet of the high-pressure turbine draw cooling airflow from the outlet section 3 of the high-pressure compressor.

[0105] The airflow parameters at section 6 of the low-pressure turbine outlet are calculated by calling the bypass loss model, and then the airflow parameters at section 8 of the inner nozzle are calculated by calling the nozzle model, where the static pressure at section 8 is equal to the static pressure of the inlet flow.

[0106] Establish equations for the torque of the high-pressure rotor compressor and the output torque of the high-pressure compressor, the torque of the high-pressure rotor turbine and the output torque of the high-pressure turbine, and the physical speed of the high-pressure shaft and the speed of the high-pressure compressor.

[0107] Establish equations for the torque of the low-pressure rotor compressor and the output torque of the low-pressure compressor and fan, the torque of the low-pressure rotor turbine and the output torque of the low-pressure turbine, and the physical speed of the low-pressure shaft and the speed of the low-pressure compressor.

[0108] In this way, all the components are connected from beginning to end. To ensure the smooth progress of the overall calculation, the following method is adopted: const, The adjustment mechanism of const is determined by iteratively calculating the test equations based on the given parameters until the common operating point of the engine, i.e., the steady-state operating point, is found. The specific steps for establishing the steady-state model are as follows:

[0109] Given the physical speed of the low-pressure rotor Physical speed of high-voltage rotor , distortion-free sub-fan Pressure ratio function value With a distorted fan Pressure ratio function value Low-pressure compressor pressure ratio function value High-pressure compressor pressure ratio function value High-pressure turbine flow ratio function value Low-pressure turbine flow ratio function value (Fan front) Distortion shunt bypass ratio (After the fan) Inner and outer bypass splitter bypass ratio Inlet airflow rate A set of initial values.

[0110] The engine component models are called to perform thermodynamic calculations, and the relative errors of 11 verification equations, i.e., a set of residuals, are output and stored in the BE_OD array. They are as follows:

[0111] (1) Low-voltage rotor power balance, i.e., fan power (including the non-distortion sub-fan) power and fans with aberrations power ) and the power of the low-pressure compressor The sum equals the power of the low-pressure turbine.

[0112] BE_OD[0] =

[0113] In the formula, This refers to the mechanical efficiency of the low-pressure rotor.

[0114] (2) High-pressure rotor power balance, i.e., the power of the high-pressure compressor With the power of the high-pressure turbine equal

[0115] BE_OD [1] =

[0116] In the formula, This represents the mechanical efficiency of the high-pressure rotor.

[0117] (3) No distortion sub-fan Inlet flow balance, i.e., no distortion sub-fan Airflow calculated from the inlet Should be with the non-distortion fan Airflow rate found on the characteristic graph equal

[0118] BE_OD [2] =

[0119] (4) Fan with distortion Inlet flow balance, i.e., with distorted sub-fan Airflow calculated from the inlet Should be equal to the air flow found on the low pressure spool fan characteristic map Should be equal to the air flow found on the low pressure spool fan characteristic map Should be equal to the air flow found on the low pressure spool fan characteristic map

[0120] BE_OD [3] =

[0121] (5) Low pressure spool compressor inlet flow balance, i.e. the air flow calculated at the low pressure spool compressor inlet Should be equal to the air flow found on the low pressure spool compressor characteristic map Should be equal to the air flow found on the low pressure spool compressor characteristic map

[0122] BE_OD [4] =

[0123] (6) High pressure spool compressor inlet flow balance, i.e. the air flow calculated at the high pressure spool compressor inlet Should be equal to the air flow found on the high pressure spool compressor characteristic map Should be equal to the air flow found on the high pressure spool compressor characteristic map

[0124] BE_OD [5] =

[0125] (7) High pressure spool turbine inlet flow balance, i.e. the gas flow calculated at the high pressure spool turbine inlet Should be equal to the gas flow found on the high pressure spool turbine characteristic map Should be equal to the gas flow found on the high pressure spool turbine characteristic map

[0126] BE_OD [6] =

[0127] (8) Low pressure spool turbine inlet flow balance, i.e. the gas flow calculated at the low pressure spool turbine inlet Should be equal to the gas flow found on the low pressure spool turbine characteristic map Should be equal to the gas flow found on the low pressure spool turbine characteristic map

[0128] BE_OD [7] =

[0129] (9) Bypass duct nozzle flow balance, i.e. the bypass duct nozzle inlet flow Should be equal to the bypass duct nozzle exit flow Should be equal to the bypass duct nozzle exit flow

[0130] BE_OD [8] =

[0131] (10) Fan nozzle flow balance, i.e. the fan nozzle inlet flow Should be equal to the fan nozzle exit flow Should be equal to the fan nozzle exit flow

[0132] BE_OD [9] =

[0133] (11) the mixed room entrance static pressure balance, namely the non-distortion sub-fan outlet static pressure with distortion sub-fan outlet static pressure equal

[0134] BE_OD

[10] =

[0135] The value of the error limit is given in advance, usually set to 1 , calculate the 2-norm of the 11 residuals, if the calculated value is less than the error limit, the engine realizes common work; if not satisfied, use the Newton-Raphson method for iterative calculation.

[0136] As Figure 4 shown, the low pressure rotor physical speed , high pressure rotor physical speed , non-distortion sub-fan pressure ratio function value , distortion sub-fan pressure ratio function value , low pressure compressor pressure ratio function value , high pressure compressor pressure ratio function value , high pressure turbine flow ratio function value , low pressure turbine flow ratio function value , (before the fan) distortion splitter duct ratio , (after the fan) internal and external splitter duct ratio , inlet air flow a small increment (generally make the original test given parameter increase 0.1% ~1%), while keeping the other test given parameter value unchanged, 11 times of engine thermal calculation, get 11 groups of residual; if the 2-norm of the 11 groups of residuals also does not meet the error limit, construct and solve the linear equation set, calculate a new set of test given parameter value, repeat the above steps until it converges to the error range.

[0137] After finding the common working point of the engine, the steady state point parameters can be used for engine thermal calculation to obtain the performance parameters of the engine such as thrust and specific fuel consumption, and the cross-section parameters in the air system such as air flow, total temperature, total pressure and total enthalpy.

[0138] The above is the specific modeling implementation method of the aircraft engine model considering inlet distortion based on parallel compressor, it should be noted that the above implementation method focuses on the improvement and innovation of the traditional model without considering inlet distortion, and the basic component model not expanded is known to those skilled in the art, which will not be described in detail here.

[0139] Moreover, the content is only the embodiment adopted for facilitating the understanding of the present application, and is not used to limit the present application. Any modification and change in the form and details can be made by any person skilled in the art without departing from the spirit and scope of the present application, but the patent protection scope of the present application shall be defined by the appended claims.

Claims

1. A method of modeling an engine's airpath model based on parallel compressor theory of inlet distortion, comprising inlet duct model, a plurality of compressor models, a plurality of turbine models, a combustion chamber model, a nozzle model, and duct loss between each model; characterized in that: Also include distortion splitter model, parallel fan model and mixing chamber model; along the flow path of the engine gas path model combination is: inlet model, distortion splitter model, parallel fan model, mixing chamber model, inner and outer bypass splitter model, low pressure compressor model and high pressure compressor model in series, combustion chamber model, high pressure turbine model and low pressure turbine model in series and nozzle model; the high pressure compressor model, low pressure compressor model, high pressure turbine model, low pressure turbine model and nozzle model front end for duct loss; the distortion splitter model is to divide the airflow at the fan inlet into two parallel airflow, respectively with two airflow model combination as a distortion splitter model; the parallel fan model is with distortion splitter model corresponding to two non-distortion sub fan And distortion sub fan Parallel fan model combination; the mixing chamber model is located at the outlet of the parallel fan model, two streams are combined into one, and then divided into two, one into the outer duct, the other into the low pressure compressor; the inlet distortion engine model recombination of engine gas path model, engine gas path model matching, when the inlet airflow distortion, then through the introduction of distortion splitter model, parallel fan model and mixing chamber model, the non-uniform flow field is divided into circumferential partition, the non-distortion sub fan And distortion sub fan Independent calculation is carried out; The two air flows of the mixing chamber model flow in parallel and are uniformly distributed in the inlet section respectively; the static pressure of the two air flows is equal when entering the mixing chamber, that is ; the heat loss in mixing is not considered, and the outlet air flow parameter is uniformly distributed; the two mixing chambers in the mixing chamber model are equal-section pipes; The outlet airflow of the mixing chamber model is distributed according to the ratio of the inner and outer ducts, and then is re-divided into two streams, which enter the inner and outer ducts respectively; the mixing chamber model comprises an energy continuity equation, a momentum balance equation of the inlet and outlet airflow of the mixing chamber model and a flow continuity equation of the inlet and outlet airflow of the mixing chamber model; The energy continuity equation: · + · = · The momentum balance equation of the inlet and outlet airflow of the mixing chamber model: + = ( + ) The flow continuity equation of the inlet and outlet airflow of the mixing chamber model: + = ( + ) where each parameter is: flow rate of the undistorted sub-fan flow rate of the outlet section total temperature total pressure static pressure specific enthalpy area velocity coefficient ; with a distorted sub-fan flow rate of the outlet section total temperature total pressure static pressure specific enthalpy area velocity coefficient ; at the outlet section of the mixing chamber model total temperature total pressure specific enthalpy velocity coefficient .

2. The method of claim 1, wherein: The distortion splitter model employs a BPR Flow distribution of two sector areas is described, i.e. undistorted sub-fan With distorted sub-fan Sector area ratio; and the degree of distortion is set according to the total temperature distortion index TP And the total pressure distortion index PP Definition.

3. The method of claim 1, wherein: The parallel fan model is described by two fan models for a non-distorted sub-fan and a distorted sub-fan whose inlet airflow passages respectively match the two fan-shaped region outlets of the distortion diverter model, and whose inlet airflow parameters respectively equal the outlet airflow parameters of the two airflow passages of the distortion diverter model.

4. The method of claim 1 or 2, wherein: The total temperature distortion index of the distortion splitter model TP = ， The total pressure distortion index PP = ; The flow parameter distribution in the two sector regions in the model is such that the inlet flow parameters in the two sector regions in the distorted splitter model are equal to the outlet flow parameters in the inlet duct model, including: the mass flow rate , total temperature , total pressure , total enthalpy , and fuel-air ratio at the outlet of the inlet duct ; the outlets of the two sector regions are divided into an outlet corresponding to the undistorted sub-fan and an outlet corresponding to the distorted sub-fan , wherein: the flow parameters at the outlet of the undistorted sub-fan are: the outlet mass flow rate , the outlet total temperature , the outlet total pressure , the outlet total enthalpy , and the outlet fuel-air ratio are equal to the inlet values of the model; the outlet mass flow rate , the outlet total temperature , · ( TP+1 ), the outlet total pressure · ( PP+1 ), the outlet total enthalpy , and the outlet fuel-air ratio of the distorted sub-fan are equal to the inlet values of the model.

5. The method of claim 1 or 3, wherein: The two inlet airflow parameters of the parallel fan model are equal to the corresponding outlet airflow parameters of the distortion splitter model.

6. A matching method of an engine air path model based on parallel compressor theory for inlet distortion, which is established by the method of any one of claims 1 to 5, characterized in that: Setting the test parameters according to the model when matching x Setting the error checking equation according to the model combination y Forming the common working equation group of the air path model matching: The test condition is that when x The values of the coefficients are such that y All are zero, indicating that the engine operation satisfies the balance condition; Since the number of components in x is greater than the number of components in y, a certain physical quantity in the parameter x is given, and the multi-element Newton method is used to solve, that is, the Newton-Raphson method is used to realize the matching of the gas path model.

7. The method of claim 6, wherein: The given parameter x consists of 12 independent variables in the engine model, including the physical speed of the low-pressure rotor. Physical speed of high-voltage rotor , distortion-free sub-fan Pressure ratio function value With a distorted fan Pressure ratio function value Low-pressure compressor pressure ratio function value High-pressure compressor pressure ratio function value High-pressure turbine flow ratio function value Low-pressure turbine flow ratio function value The distortion shunt bypass ratio in front of the fan The ratio of the inner and outer bypass ducts after the fan to the bypass ratio Inlet airflow rate Main combustion chamber outlet total temperature The corresponding error verification equation y consists of 11 residual equations that satisfy the common working balance condition of the component models: including the low-pressure rotor power balance equation, the high-pressure rotor power balance equation, and the distortion-free sub-fan equation. Inlet flow balance equation, fan with distortion Inlet flow balance equation, low-pressure compressor inlet flow balance equation, high-pressure compressor inlet flow balance equation, high-pressure turbine inlet flow balance equation, low-pressure turbine inlet flow balance equation, inner duct nozzle flow balance equation, outer bypass duct nozzle flow balance equation, mixing chamber inlet static pressure balance equation.

8. A method of using an engine gas path model based on parallel compressor theory for inlet distortion, the method being established by any one of claims 1 to 5, characterized in that: The gas path model completed by the matching method of claims 6-7 is used for engine thermodynamic calculation to obtain the performance parameters of the engine, such as thrust and specific fuel consumption, and the airflow flow, total temperature, total pressure and total enthalpy cross-section parameters in the air system.

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