An engine variable-dimension numerical simulation method and device

Abstract

This application belongs to the field of engine simulation technology, and relates to a variable-dimension numerical simulation method and device for an engine. The method includes: calculating the parameters of a contra-rotating propeller fan based on a three-dimensional lifting line model of the contra-rotating propeller fan; determining the axial average velocity of the inlet airflow at the inlet of the intake duct; determining the cross-sectional parameters at the inlet of the intake duct; calculating the cross-sectional parameters at the outlet of the intake duct; dividing the airflow at the outlet of the intake duct into two streams, one stream is distorted and the other stream is not distorted, and mixing them at the outlet to determine the cross-sectional parameters at the outlet of the low-pressure compressor; calculating the inlet and outlet cross-sectional parameters of each component according to the zero-dimensional model of each component of the engine; constructing a balance equation according to the flow of the airflow through each component of the engine; constructing a balance equation according to the balance relationship between the shaft power and torque output by the free turbine and the power and torque calculated by the three-dimensional lifting line model of the contra-rotating propeller fan; iteratively solving the balance equation to determine the initial guess value, and when the iteration converges, calculating the engine performance. This application has high simulation accuracy and fast speed.

Description

Technical Field

[0001] This application belongs to the technical field of engine simulation, and particularly relates to a variable-dimensional numerical simulation method and device for engines. Background Technique

[0002] The whole-engine simulation technology of aeroengines is an important means in the conceptual design, R & D, manufacturing, testing, and use processes of aeroengines. With the help of more accurate whole-engine simulation tools for aeroengines, the design and test cycles can be significantly reduced, and costs can be lowered. However, the traditional zero-dimensional whole-engine model of aeroengines established based on component characteristics is highly dependent on component characteristics, and as the engine configuration gradually becomes more complex, there are convergence problems in the application process of the zero-dimensional simulation model. The quasi-three-dimensional or three-dimensional whole-engine simulation of aeroengines requires a large amount of computing resources, has a slow computing speed, and it is difficult to ensure the convergence and stability of the large and complex regional flow field simulation with multi-field coupling. Therefore, it is necessary to develop a high-precision whole-engine simulation method that can achieve fast computing and has good model stability and convergence.

[0003] As a new generation of high-efficiency, energy-saving, and green power, the open-rotor engine has always been a research hotspot in recent years. Currently, the whole-engine simulation method for open-rotor engines is mainly based on component-level zero-dimensional models, and the simulation calculation accuracy is limited.

[0004] In terms of variable-dimensional simulation of engines, in the prior art, the Chinese invention patent with the publication number CN114781153A conducts three-dimensional simulation on the fan component and proposes a performance simulation process control method for whole-engine variable-dimensional simulation. The Chinese invention patent with the publication number CN118114595A conducts three-dimensional simulation on the compressor and turbine and gives a coupling calculation method for variable-dimensional simulation of gas turbines. However, there is currently no research on variable-dimensional simulation for open-rotor engines.

[0005] In addition, for the gear-driven open-rotor engine with a tractor structure, due to the interference of the wake vortices of the contra-rotating propfans, a certain degree of inlet distortion will occur at the engine inlet, affecting the stability of the compressor. However, in the prior art, there is no research on the inlet distortion of open-rotor engines. Summary of the Invention

[0006] To solve the above problems, this application provides a variable-dimensional numerical simulation method and device for engines.

[0007] The first aspect of this application provides a variable-dimensional numerical simulation method for engines, mainly including:

[0008] Step S1: Given the initial guess values of the front propeller speed, the initial guess value of the front propeller pitch angle, the initial guess value of the rear propeller speed, and the initial guess value of the rear propeller pitch angle of the contra-rotating propeller fan, calculate the total thrust, the front propeller power, the rear propeller power, the front propeller torque, and the rear propeller torque of the contra-rotating propeller fan based on the three-dimensional lifting line model of the contra-rotating propeller fan;

[0009] Step S2: Determine the axial average velocity of the inlet air flow at the inlet of the inlet duct behind the contra-rotating propeller fan according to the total thrust of the contra-rotating propeller fan;

[0010] Step S3: Determine the cross-sectional parameters at the inlet of the inlet duct according to the axial average velocity of the inlet air flow at the inlet of the inlet duct;

[0011] Step S4: Calculate the cross-sectional parameters at the outlet of the inlet duct according to the zero-dimensional model of the inlet duct;

[0012] Step S5: Divide the air flow at the outlet of the inlet duct into two streams. One stream flows to the distorted low-pressure compressor, and the other stream flows to the non-distorted low-pressure compressor. Determine the cross-sectional parameters at the inlet of the distorted low-pressure compressor according to the given pressure distortion index. Then, determine the cross-sectional parameters at the outlet of the distorted low-pressure compressor according to the given pressure ratio of the distorted low-pressure compressor and the initial guess value of the low-pressure compressor speed. At the same time, determine the cross-sectional parameters at the outlet of the non-distorted low-pressure compressor according to the given pressure ratio of the non-distorted low-pressure compressor and the initial guess value of the low-pressure compressor speed. Mix the air flow at the outlet of the distorted low-pressure compressor and the air flow at the outlet of the non-distorted low-pressure compressor, and calculate the cross-sectional parameters at the outlet of the low-pressure compressor through the mixing model. Construct the first balance equation according to the static pressure balance condition between the outlet of the distorted low-pressure compressor and the outlet of the non-distorted low-pressure compressor;

[0013] Step S6: Given the initial guess values of the pressure ratio of the high-pressure compressor, the initial guess value of the high-pressure compressor speed, the initial guess value of the fuel supply of the combustion chamber, the initial guess value of the pressure drop ratio of the high-pressure turbine, the initial guess value of the pressure drop ratio of the low-pressure turbine, the initial guess value of the pressure drop ratio of the free turbine, and the initial guess value of the free turbine speed, calculate the cross-sectional parameters at the inlet and outlet of each component based on the zero-dimensional models of the components connected in sequence behind the low-pressure compressor, including the high-pressure compressor, the combustion chamber, the high-pressure turbine, the low-pressure turbine, the free turbine, and the tail nozzle;

[0014] Step S7: Construct the second to eighth balance equations according to the seven balance conditions of the flow continuity between the high-pressure compressor and the low-pressure compressor, the flow continuity between the combustion chamber and the high-pressure turbine, the power balance on the high-pressure shaft, the flow continuity between the high-pressure turbine and the low-pressure turbine, the power balance on the low-pressure shaft, the flow continuity between the low-pressure turbine and the free turbine, and the flow continuity between the free turbine and the tail nozzle;

[0015] Step S8: Construct the ninth balance equation according to the power balance relationship that the shaft power output by the free turbine needs to satisfy the sum of the front propeller power and the rear propeller power calculated based on the three-dimensional lifting line model of the contra-rotating propeller fan;

[0016] Step S9: Calculate the torque of the sun shaft of the planetary gear reducer connected thereto according to the shaft power and rotational speed output by the free turbine. According to the connection relationship between the planetary gear reducer and the front row of propeller fans and the rear row of propeller fans, distribute the sun shaft torque to the front row of propeller fans and the rear row of propeller fans. Based on the relationship that the distributed torque is balanced with the front propeller torque and the rear propeller torque calculated based on the contra-rotating propeller fan three-dimensional lifting line model respectively, construct the tenth balance equation and the eleventh balance equation;

[0017] Step S10: Select three of the above fourteen independent variables that need to be given initial guess values as control parameters. By iterating the initial guess values of the remaining eleven independent variables, solve the common working equation set composed of the above eleven balance equations. When the iteration converges, calculate the engine performance;

[0018] Wherein, the cross-section parameters include one or more of flow rate, area, total temperature, total pressure and total enthalpy.

[0019] Preferably, step S2 further includes:

[0020] Step S21: Determine the axial average induced velocity at the contra-rotating propeller fan according to the total thrust of the contra-rotating propeller fan;

[0021] Step S22: Calculate the axial average velocity of the air flow at the inlet of the inlet duct according to the distance between the contra-rotating propeller fan and the inlet of the inlet duct and the axial average induced velocity.

[0022] Preferably, in step S5, the outlet static pressures of the distorted low-pressure compressor and the non-distorted low-pressure compressor are calculated based on the inlet cross-section parameters of each of them, assuming that the inlet and outlet areas of the low-pressure compressor remain unchanged, and the outlet static pressures of each of them are calculated by the inlet area in the inlet cross-section parameters of each of them.

[0023] Preferably, in step S10, the three selected control parameters include the front propeller pitch angle, the rear propeller pitch angle and the fuel supply amount of the combustion chamber.

[0024] Preferably, in step S10, the common working equation set composed of the above eleven balance equations is solved by the Newton iteration method, and the Jacobian matrix constructed by the Newton iteration method is calculated in parallel through multi-threading.

[0025] The second aspect of the present application provides an engine variable-dimension numerical simulation device, mainly including:

[0026] A contra-rotating propeller fan parameter calculation module, configured to give initial guess values of the rotational speed of the front propeller of the contra-rotating propeller fan, the initial guess value of the front propeller pitch angle, the initial guess value of the rotational speed of the rear propeller and the initial guess value of the rear propeller pitch angle, and calculate the total thrust, the front propeller power, the rear propeller power, the front propeller torque and the rear propeller torque of the contra-rotating propeller fan based on the contra-rotating propeller fan three-dimensional lifting line model;

[0027] The contra-rotating propeller fan and inlet duct aerodynamic coupling module is used to determine the axial average velocity of the inlet air flow at the inlet of the inlet duct behind the contra-rotating propeller fan according to the total thrust of the contra-rotating propeller fan, and then determine the cross-sectional parameters at the inlet of the inlet duct according to the axial average velocity of the inlet air flow at the inlet of the inlet duct;

[0028] The inlet duct parameter calculation module is used to calculate the cross-sectional parameters at the outlet of the inlet duct according to the zero-dimensional model of the inlet duct;

[0029] The low-pressure compressor parameter calculation module is used to divide the outlet air flow of the inlet duct into two streams. One stream flows to the distorted low-pressure compressor, and the other stream flows to the non-distorted low-pressure compressor. Determine the cross-sectional parameters at the inlet of the distorted low-pressure compressor according to the given pressure distortion index, and then determine the cross-sectional parameters at the outlet of the distorted low-pressure compressor according to the given pressure ratio of the distorted low-pressure compressor compared with the initial guess value and the initial guess value of the low-pressure compressor speed. At the same time, determine the cross-sectional parameters at the outlet of the non-distorted low-pressure compressor according to the given pressure ratio of the non-distorted low-pressure compressor compared with the initial guess value and the initial guess value of the low-pressure compressor speed. Mix the air flow at the outlet of the distorted low-pressure compressor with the air flow at the outlet of the non-distorted low-pressure compressor, and calculate the cross-sectional parameters at the outlet of the low-pressure compressor through the mixing model. Construct the first balance equation according to the static pressure balance condition between the outlet of the distorted low-pressure compressor and the outlet of the non-distorted low-pressure compressor;

[0030] The other component parameter calculation module is used to give the initial guess values of the pressure ratio of the high-pressure compressor, the initial guess value of the high-pressure compressor speed, the initial guess value of the fuel supply of the combustion chamber, the initial guess value of the pressure drop ratio of the high-pressure turbine, the initial guess value of the pressure drop ratio of the low-pressure turbine, the initial guess value of the pressure drop ratio of the free turbine, and the initial guess value of the free turbine speed, and calculate the inlet and outlet cross-sectional parameters of each component based on the zero-dimensional models of the components connected in sequence behind the low-pressure compressor, including the high-pressure compressor, the combustion chamber, the high-pressure turbine, the low-pressure turbine, the free turbine, and the tail nozzle;

[0031] The engine common working balance equation construction module is used to construct the second to eighth balance equations according to the seven balance conditions of the flow continuity between the high-pressure compressor and the low-pressure compressor, the flow continuity between the combustion chamber and the high-pressure turbine, the power balance on the high-pressure shaft, the flow continuity between the high-pressure turbine and the low-pressure turbine, the power balance on the low-pressure shaft, the flow continuity between the low-pressure turbine and the free turbine, and the flow continuity between the free turbine and the tail nozzle;

[0032] The gear reducer power transmission calculation module is used to construct the ninth balance equation according to the power balance relationship that the shaft power output by the free turbine needs to satisfy the sum of the front propeller power and the rear propeller power calculated based on the three-dimensional lift line model of the contra-rotating propeller fan;

[0033] The gear reducer torque transmission calculation module is used to calculate the sun shaft torque of the planetary gear reducer connected thereto according to the shaft power and rotational speed output by the free turbine, and distribute the sun shaft torque to the front row of propfans and the rear row of propfans according to the connection relationship between the planetary gear reducer and the front row of propfans and the rear row of propfans. According to the relationship that the distributed torques are respectively balanced with the front propeller torque and the rear propeller torque calculated based on the contra-rotating propfan three-dimensional lifting line model, the tenth balance equation and the eleventh balance equation are constructed;

[0034] The co-working equations solving module is used to select three of the above fourteen independent variables that need to be given initial guess values as control parameters, and solve the co-working equations composed of the above eleven balance equations by iterating the initial guess values of the remaining eleven independent variables. When the iteration converges, the engine performance is calculated;

[0035] Wherein, the cross-section parameters include one or more of flow rate, area, total temperature, total pressure and total enthalpy.

[0036] Preferably, the contra-rotating propfan and inlet duct aerodynamic coupling module includes:

[0037] The contra-rotating propfan axial average induced velocity calculation unit is used to determine the axial average induced velocity at the contra-rotating propfan according to the total thrust of the contra-rotating propfan;

[0038] The air flow axial average velocity calculation unit is used to calculate the axial average velocity of the air flow at the inlet of the inlet duct according to the distance between the contra-rotating propfan and the inlet of the inlet duct and the axial average induced velocity.

[0039] Preferably, in the low-pressure compressor parameter calculation module, the outlet static pressures of the distorted low-pressure compressor and the non-distorted low-pressure compressor are calculated from their respective inlet cross-section parameters based on the assumption that the inlet and outlet areas of the low-pressure compressor remain unchanged, and the outlet static pressures are calculated from the inlet areas in their respective inlet cross-section parameters.

[0040] Preferably, in the co-working equations solving module, the three control parameters selected include the front propeller pitch angle, the rear propeller pitch angle and the fuel supply amount of the combustion chamber.

[0041] Preferably, in the co-working equations solving module, the co-working equations composed of the above eleven balance equations are solved by the Newton iteration method, and the Jacobian matrix constructed by the Newton iteration method is calculated in parallel through multi-threading.

[0042] This application realizes the high-fidelity calculation of the overall performance of the open rotor engine, with high calculation accuracy and fast speed. Description of the Drawings

[0043] Figure 1This is a flowchart of a preferred embodiment of the engine variable-dimension numerical simulation method of the present application.

[0044] Figure 2 This is a schematic diagram of the positional relationship and cross-section numbers of the components of a tractor open-rotor engine. Specific embodiments

[0045] To make the purpose, technical solutions, and advantages of the implementation of the present application clearer, the technical solutions in the embodiments of the present application will be described in more detail below with reference to the accompanying drawings in the embodiments of the present application. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present application. The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0046] The present application provides an engine variable-dimension numerical simulation method and device. Considering the disadvantages of large computational volume in using a whole-engine three-dimensional model and inaccurate calculation in using a whole-engine zero-dimensional model in the prior art, the present application combines a three-dimensional model and a zero-dimensional model. In the following step S1, a three-dimensional or quasi-three-dimensional lift-line model is used for the contra-rotating propfans in the engine structure, and the true characteristics of the components can be directly obtained, avoiding the problem of dependence on characteristic maps, thereby avoiding the errors caused by characteristic scaling and improving the simulation accuracy of the components. Except for the contra-rotating propfans, other engine components, including the zero-dimensional model of the intake duct introduced in step S4, the zero-dimensional models of the distorted low-pressure compressor and the non-distorted low-pressure compressor introduced in step S5, and the zero-dimensional models of the high-pressure compressor, combustion chamber, high-pressure turbine, low-pressure turbine, free turbine, and nozzle components introduced in step S6, still use the zero-dimensional or quasi-one-dimensional models of the prior art. In the following steps S2-S3, aerodynamic coupling is performed between the three-dimensional lift-line model of the contra-rotating propfans and the zero-dimensional model of the engine intake duct. In the following steps S8-S9, structural coupling is performed between the zero-dimensional model of the engine free turbine and the three-dimensional lift-line model of the contra-rotating propfans. Through these two coupling methods, variable-dimension numerical simulation of the whole open-rotor engine is achieved. The following is a detailed description.

[0047] The first aspect of the present application provides an engine variable-dimension numerical simulation method, as Figure 1 shown, mainly including:

[0048] Step S1: Given the initial guess values of the front propeller rotational speed, front propeller pitch angle, rear propeller rotational speed, and rear propeller pitch angle of the contra-rotating propeller fan, calculate the total thrust, front propeller power, rear propeller power, front propeller torque, and rear propeller torque of the contra-rotating propeller fan based on the three-dimensional lifting line model of the contra-rotating propeller fan;

[0049] Step S2: Determine the axial average velocity of the inlet air flow at the inlet of the inlet duct behind the contra-rotating propeller fan according to the total thrust of the contra-rotating propeller fan;

[0050] Step S3: Determine the cross-sectional parameters at the inlet of the inlet duct according to the axial average velocity of the inlet air flow at the inlet of the inlet duct;

[0051] Step S4: Calculate the cross-sectional parameters at the outlet of the inlet duct according to the zero-dimensional model of the inlet duct;

[0052] Step S5: Divide the air flow at the outlet of the inlet duct into two streams. One stream flows to the distorted low-pressure compressor, and the other stream flows to the non-distorted low-pressure compressor. Determine the cross-sectional parameters at the inlet of the distorted low-pressure compressor according to the given pressure distortion index, and then determine the cross-sectional parameters at the outlet of the distorted low-pressure compressor according to the given pressure ratio of the distorted low-pressure compressor and the initial guess value of the rotational speed of the low-pressure compressor. At the same time, determine the cross-sectional parameters at the outlet of the non-distorted low-pressure compressor according to the given pressure ratio of the non-distorted low-pressure compressor and the initial guess value of the rotational speed of the low-pressure compressor. Mix the air flow at the outlet of the distorted low-pressure compressor and the air flow at the outlet of the non-distorted low-pressure compressor, and calculate the cross-sectional parameters at the outlet of the low-pressure compressor through the mixing model. Construct the first balance equation according to the static pressure balance condition between the outlet of the distorted low-pressure compressor and the outlet of the non-distorted low-pressure compressor;

[0053] Step S6: Given the initial guess values of the pressure ratio of the high-pressure compressor, the rotational speed of the high-pressure compressor, the fuel supply of the combustion chamber, the pressure ratio drop of the high-pressure turbine, the pressure ratio drop of the low-pressure turbine, the pressure ratio drop of the free turbine, and the rotational speed of the free turbine, calculate the cross-sectional parameters at the inlet and outlet of each component based on the zero-dimensional models of the components including the high-pressure compressor, combustion chamber, high-pressure turbine, low-pressure turbine, free turbine, and nozzle connected in sequence behind the low-pressure compressor;

[0054] Step S7: Construct the second to eighth balance equations according to the seven balance conditions of the flow continuity between the high-pressure compressor and the low-pressure compressor, the flow continuity between the combustion chamber and the high-pressure turbine, the power balance on the high-pressure shaft, the flow continuity between the high-pressure turbine and the low-pressure turbine, the power balance on the low-pressure shaft, the flow continuity between the low-pressure turbine and the free turbine, and the flow continuity between the free turbine and the nozzle;

[0055] Step S8: Construct the ninth balance equation according to the power balance relationship that the shaft power output by the free turbine needs to satisfy the sum of the front propeller power and the rear propeller power calculated based on the three-dimensional lifting line model of the contra-rotating propeller fan;

[0056] Step S9: Calculate the sun shaft torque of the planetary gear reducer connected thereto based on the shaft power and rotational speed output by the free turbine. According to the connection relationship between the planetary gear reducer, the front row of paddle fans, and the rear row of paddle fans, distribute the sun shaft torque to the front row of paddle fans and the rear row of paddle fans. Based on the relationship of the distributed torque being balanced with the front paddle torque and the rear paddle torque calculated based on the contra-rotating paddle fan three-dimensional lifting line model respectively, construct the tenth balance equation and the eleventh balance equation;

[0057] Step S10: Select three of the above fourteen independent variables that need to be given initial guess values as control parameters, and solve the common working equation set composed of the above eleven balance equations by iterating the initial guess values of the remaining eleven independent variables. When the iteration converges, calculate the engine performance;

[0058] Wherein, the cross-section parameters include one or more of flow rate, area, total temperature, total pressure, and total enthalpy.

[0059] First, before step S1, calculate the air flow velocity , temperature , pressure and other parameters at the inlet of the contra-rotating paddle fan according to the given atmospheric conditions (altitude, flight Mach number, temperature, etc.). Then, in step S1, give the initial guess values of the front paddle rotational speed n1, the front paddle pitch angle β1, the rear paddle rotational speed n2, and the rear paddle pitch angle β2, and calculate the total thrust F CRP , total power P CRP , efficiency η CRP , front paddle power P1, rear paddle power P2, front paddle torque Q1, and rear paddle torque Q2 through the established contra-rotating paddle fan three-dimensional lifting line model.

[0060] After that, in step S2, calculate the axial average air flow velocity at the inlet of the inlet duct.

[0061] In some alternative embodiments, step S2 further includes:

[0062] Step S21: Determine the axial average induced velocity at the position of the contra-rotating paddle fan according to the total thrust of the contra-rotating paddle fan;

[0063] Step S22: Calculate the axial average air flow velocity at the inlet of the inlet duct according to the distance between the contra-rotating paddle fan and the inlet of the inlet duct, and the axial average induced velocity.

[0064] In step S21, calculate the axial average induced velocity at the position of the contra-rotating paddle fan according to the momentum theorem :

[0065] .

[0066] Where ρ is the atmospheric density, Adisk is the fan area of the contra-rotating propeller fan.

[0067] After that, in step S22, according to the principle of flow channel contraction, the axial average velocity of the air flow at the inlet position of the engine inlet duct under the interference of the contra-rotating propeller fan is calculated :

[0068] ;

[0069] where z is the distance between the downstream of the contra-rotating propeller fan and the inlet of the inlet duct, and R is the fan radius of the contra-rotating propeller fan.

[0070] At the same time, the three-dimensional velocity distribution of the air flow at the inlet cross-section of the inlet duct can also be obtained according to the three-dimensional lift line model of the contra-rotating propeller fan.

[0071] After that, in step S3, through the average velocity at the inlet of the inlet duct , the parameters of the inlet cross-section of the inlet duct after considering the interference of the contra-rotating propeller fan can be obtained. The cross-section parameters include one or more of flow rate, area, total temperature, total pressure and total enthalpy. Here, it mainly includes the total temperature T t1 , total pressure p t1 , total enthalpy h t1 at the inlet of the inlet duct. Referring to Figure 2 , the cross-section number of the front side of the inlet duct is 1. Therefore, the subscript t1 is usually used to represent the inlet cross-section parameters. For another example, the cross-section number of the outlet of the low-pressure compressor is 25, then the total enthalpy at the outlet of the low-pressure compressor is h t25 , and the total temperature at the outlet is T t25 .

[0072] With the above cross-section parameters at the inlet of the inlet duct, referring to Figure 2 , subsequent simulation calculations can be carried out using the existing zero-dimensional models of various components of the engine. Among them, in step S4, the average total temperature , average total pressure , and average total enthalpy of the outlet parameters of the inlet duct are calculated by the zero-dimensional model of the inlet duct.

[0073] After that, in step S5, due to the wake effect of the contra-rotating propeller fan, the actual air flow at the inlet of the inlet duct is uneven, and there is an inlet distortion problem. Therefore, in this application, a parallel compressor model is established for the low-pressure compressor to consider the inlet distortion problem.

[0074] In some alternative embodiments, in step S5, the outlet static pressures of the distorted low-pressure compressor and the non-distorted low-pressure compressor are calculated based on the inlet cross-section parameters of each of them, assuming that the inlet and outlet areas of the low-pressure compressor remain unchanged, and the outlet static pressures of each of them are calculated from the inlet areas in the inlet cross-section parameters of each of them. The parallel compressor model is described in detail below.

[0075] (1) The airflow at the exit of the inlet duct is divided into two streams. One stream flows to the distorted low-pressure compressor a, and the other stream flows to the undistorted low-pressure compressor b. The distorted low-pressure compressor a and the undistorted low-pressure compressor b only have different inlet conditions but the same rotational speed. The two compressors operate in parallel and then mix at the exit. Given the pressure distortion index and the temperature distortion index , the total inlet temperature and total pressure of the distorted low-pressure compressor a can be calculated.

[0076] (2) For the low-pressure compressor a, based on the initial guess value of the pressure ratio Z LCa of the given distorted low pressure (here, the "pressure ratio" is a variable z, and its expression is z = (π - π min ) / (π max - π min ), where π is the pressure ratio, π max is the maximum pressure ratio on the constant rotational speed characteristic line of the characteristic diagram, and π min is the minimum pressure ratio on the constant rotational speed characteristic line of the characteristic diagram) and the initial guess value of the rotational speed n LC of the low-pressure compressor, the flow rate W 2a,cor and efficiency η LCa of the low-pressure compressor are obtained by interpolation through the characteristic diagram. Using the zero-dimensional model of the distorted low-pressure compressor, the outlet flow rate W 2a , total temperature , total pressure , total enthalpy and power P LCa of the distorted low-pressure compressor a can be further calculated. From W 2a and , the inlet and outlet cross-sectional areas A 2a of the distorted low-pressure compressor a can be calculated. Assuming that the areas at the inlet and outlet of the low-pressure compressor remain unchanged, based on the area A 2a and the outlet total parameters of the distorted low-pressure compressor a, the outlet static pressure of the distorted low-pressure compressor a can be iteratively calculated.

[0077] (3) For the undistorted low-pressure compressor b, based on the initial guess value of the pressure ratio Z LCb of the given undistorted low pressure and the initial guess value of the rotational speed n LC of the low-pressure compressor given in the previous step, the corrected flow rate W 2b,cor and efficiency η LCb of the low-pressure compressor are obtained by interpolation through the characteristic diagram. Using the zero-dimensional model of the undistorted low-pressure compressor, the outlet flow rate W 2b , total temperature , total pressure , total enthalpy and power P LCb . From W 2b and the inlet and outlet cross-sectional areas A of the non-distorted low-pressure compressor b can be calculated 2b . Assuming that the areas at the inlet and outlet of the non-distorted low-pressure compressor b remain unchanged, based on the area A 2b and the total parameters at the outlet of the non-distorted low-pressure compressor b, the outlet static pressure of the non-distorted low-pressure compressor b can be iteratively calculated .

[0078] (4) Assume that the two airflows are mixed after coming out, and the outlet flow rate of the low-pressure compressor after mixing is W 25 = W 2a + W 2b , the outlet total enthalpy is h t25 = (W 2a h t25,a + W 2b h t25,b ) / W 25 , and the outlet total temperature T of the low-pressure compressor is iteratively calculated from h t25 . The total power P of the low-pressure compressor is calculated from P t25 = P LC + P LCa + P LCb LC .

[0079] The static pressure balance condition that needs to be satisfied in the mixing process of the two airflows at the outlet cross-section of the low-pressure compressor is: , so the balance equation that needs to be satisfied is obtained:

[0080] y1 = (p s25,a - p s25,b ) / p s25,b .

[0081] After that, in step S6, referring to Figure 1 and Figure 2 , the mixed airflow enters the high-pressure compressor, combustion chamber, high-pressure turbine, low-pressure turbine, free turbine, and tail nozzle in sequence. These components all adopt the traditional zero-dimensional model, and by transferring the inlet and outlet parameters of each component between different components, a quasi-one-dimensional simulation model of the engine can be obtained.

[0082] In the quasi-one-dimensional engine model from the inlet duct to the tail nozzle, in addition to the 3 initial guess values (the pressure ratio Z LCb of the non-distorted low pressure, the pressure ratio Z LCa of the distorted low pressure, and the rotational speed n LC of the low-pressure compressor) required for the parallel low-pressure compressor model in step S5, the remaining components also need to be given the following 7 initial guess values: the pressure ratio Z of the high-pressure compressorHC 、 High-pressure compressor speed n HC 、 Combustor fuel supply W fb 、 High-pressure turbine pressure ratio drop π HT 、 Low-pressure turbine pressure ratio drop π LT 、 Free turbine pressure ratio drop π FT 、 Free turbine speed n FT 。

[0083] In step S7, according to the balance conditions of the engine (continuous flow, equal power, equal speed, pressure balance), the following balance equations need to be satisfied for the quasi-one-dimensional engine model from the intake duct to the tailpipe:

[0084] 。

[0085] In the formula, is the outlet static pressure balance parameter of the two parallel low-pressure compressors a and b in the parallel compressor model of the low-pressure compressor. When it is 0, it indicates balance. is the flow continuity parameter between the high-pressure compressor and the low-pressure compressor. When it is 0, it indicates continuous flow. The same applies hereinafter and will not be elaborated. is the outlet flow of the low-pressure compressor. is the inlet flow of the high-pressure compressor. is the flow continuity parameter between the combustor and the high-pressure turbine. is the outlet flow of the combustor. is the inlet flow of the high-pressure turbine. is the power balance parameter on the high-pressure shaft. is the output power of the high-pressure turbine. is the power of the high-pressure compressor. High-pressure power transfer efficiency. is the flow continuity parameter between the high-pressure turbine and the low-pressure turbine. is the outlet flow of the high-pressure turbine. is the inlet flow of the low-pressure turbine. is the power balance parameter on the low-pressure shaft. is the output power of the low-pressure turbine. is the low-pressure power transfer efficiency. is the total power of the low-pressure compressor. is the flow continuity parameter between the low-pressure turbine and the free turbine. is the outlet flow of the low-pressure turbine. is the inlet flow of the free turbine. is the flow continuity parameter between the free turbine and the tailpipe. is the outlet flow of the free turbine. Tailpipe inlet flow.

[0086] After that, in step S9, referring to Figure 2 , the shaft power P FT and rotational speed n FT output from the free turbine are transmitted through the mechanical shaft to the sun shaft of the planetary gear reducer. At this time, the torque of the sun shaft is Q sun . The shaft power P FT is power-distributed by the planetary gear reducer, and the front row of paddle fans is driven by the planet carrier of the reducer, and the outer gear ring of the reducer drives the rear row of paddle fans.

[0087] Through the given radius ratio R p / R s of the planet gears and the sun gear of the planetary gear reducer, the torque Q star of the planet carrier and the torque of the outer gear ring as Q ring can be calculated according to the following formula:

[0088] .

[0089] Among them, is the transmission efficiency. Through the planetary gear reducer, the power transmitted to the front row of paddle fans is P1, and the power transmitted to the rear row of paddle fans is P2. The shaft power P FT output from the free turbine needs to be equal to the total power P CRP calculated in step S1. The torque Q star of the planet carrier of the planetary gear reducer needs to be equal to the front paddle torque Q1 of the front row of paddle fans, and the torque Q ring of the outer gear ring of the planetary gear reducer needs to be equal to the rear paddle torque Q2 of the rear row of paddle fans. Therefore, among the three components of the free turbine, the planetary gear reducer and the contra-rotating paddle fans, the following 3 balance conditions need to be satisfied:

[0090] .

[0091] In the formula, ΔP CRP is the balance parameter of the output power of the contra-rotating paddle fans and the free turbine, ΔQ1 is the torque balance parameter of the front paddle and the planet carrier; ΔQ2 is the torque balance parameter of the rear paddle and the ring gear.

[0092] Finally, in step S10, according to the previous steps, it can be known that the open rotor engine has 14 independent variables that need to be given initial guess values, which are: β1, n1, β2, n2, Z LCa , Z LCb , n LC , Z HC , n HC , W fb , π HT , π LT , π FT , n FTHowever, there are 11 balance equations for the engine. To close the equations, 3 variables need to be selected from the above independent variables as control parameters through a control strategy, and the remaining 11 independent variables serve as the free variables x required for the co - working equations y of the engine.

[0093] In some alternative embodiments, in step S10, the three selected control parameters include the pitch angle β1 of the front propeller, the pitch angle β2 of the rear propeller, and the fuel supply W to the combustion chamber. fb 。

[0094] Accordingly, the co - working equations of the open - rotor engine considering inlet distortion can be expressed as:

[0095] 。

[0096] In some alternative embodiments, in step S10, the co - working equations composed of the above - constructed eleven balance equations are solved by the Newton - Raphson method, and the Jacobian matrix constructed by the Newton - Raphson method is calculated in parallel through multi - threading.

[0097] The Newton - Raphson method is used to solve the 11 - dimensional co - working non - linear equations of the open - rotor engine variable - dimension simulation process in step 10, so that y = y(x)=0. Arbitrarily take the initial value x0 of x, and construct the following iterative format for iterative calculation:

[0098] ;

[0099] where k is the number of iterations, J -1 is the inverse matrix of the Jacobian matrix J, and its specific expression is as follows:

[0100] 。

[0101] When the residual vector ||y|| of the co - working equations < 10 -4 , it is considered that the calculation converges, and the working state of the engine can be obtained. Otherwise, the value of the independent variable x is updated through the Jacobian matrix J. After the program converges, calculate the performance of the engine, including performance parameters such as thrust, specific fuel consumption, power, and propulsion efficiency.

[0102] In the open - rotor engine variable - dimension numerical simulation program, since an 11 - dimensional Jacobian matrix needs to be calculated, at each iteration step, the quasi - three - dimensional lifting - line model of the contra - rotating propeller fan needs to be called 12 times, where 11 times are for calculating the 11 - dimensional Jacobian matrix and 1 time is for judging the convergence state. Since it takes about 20 s for the contra - rotating propeller fan module to calculate a working point, if single - thread calculation is used, each iterative calculation takes 4 min. If it converges after 5 iterations, at least 20 min are required to obtain the performance at a non - design point, which cannot meet the purpose of rapid design and calculation.

[0103] Therefore, when calculating the Jacobian matrix in this application, a multi-threaded parallel computing method is adopted. Since the partial derivatives of the Jacobian matrix are independent of each other, by using 11 threads to simultaneously carry out parallel computing of small perturbations of 11 independent variables, only 40 s is required for one iteration, and only 3.3 min is required for 5 times of convergence to obtain the performance at a non-design point, greatly saving the computing time.

[0104] This application can achieve rapid calculation of engine performance. The calculation time at the design point is about 20 s. For the calculation process at the non-design point, the number of convergence steps of Newton iteration is 4 - 6 steps, and the calculation time is about 2.5 min - 4 min. The convergence and stability of the program are good.

[0105] The second aspect of this application provides an engine variable-dimension numerical simulation device corresponding to the above method, which mainly includes:

[0106] A contra-rotating propeller fan parameter calculation module, which is used to give the initial guess values of the front propeller speed, the front propeller pitch angle, the rear propeller speed, and the rear propeller pitch angle of the contra-rotating propeller fan, and calculate the total thrust, the front propeller power, the rear propeller power, the front propeller torque, and the rear propeller torque of the contra-rotating propeller fan based on the three-dimensional lifting line model of the contra-rotating propeller fan;

[0107] A contra-rotating propeller fan and inlet duct aerodynamic coupling module, which is used to determine the axial average velocity of the inlet air flow at the inlet of the inlet duct behind the contra-rotating propeller fan according to the total thrust of the contra-rotating propeller fan, and then determine the cross-sectional parameters at the inlet of the inlet duct according to the axial average velocity of the inlet air flow at the inlet of the inlet duct;

[0108] An inlet duct parameter calculation module, which is used to calculate the cross-sectional parameters at the outlet of the inlet duct according to the zero-dimensional model of the inlet duct;

[0109] A low-pressure compressor parameter calculation module, which is used to divide the outlet air flow of the inlet duct into two streams, one stream flows to the distorted low-pressure compressor, and the other stream flows to the non-distorted low-pressure compressor. Determine the cross-sectional parameters at the inlet of the distorted low-pressure compressor according to the given pressure distortion index, and then determine the cross-sectional parameters at the outlet of the distorted low-pressure compressor according to the given pressure ratio initial guess value and the low-pressure compressor speed initial guess value of the distorted low-pressure compressor. At the same time, determine the cross-sectional parameters at the outlet of the non-distorted low-pressure compressor according to the given pressure ratio initial guess value and the low-pressure compressor speed initial guess value of the non-distorted low-pressure compressor. Mix the air flow at the outlet of the distorted low-pressure compressor and the air flow at the outlet of the non-distorted low-pressure compressor, and calculate the cross-sectional parameters at the outlet of the low-pressure compressor through the mixing model. Construct the first balance equation according to the static pressure balance condition between the outlet of the distorted low-pressure compressor and the outlet of the non-distorted low-pressure compressor;

[0110] Other component parameter calculation module, which is used to give the initial guess values of the pressure ratio of the high-pressure compressor, the initial guess value of the high-pressure compressor speed, the initial guess value of the fuel supply of the combustion chamber, the initial guess value of the pressure ratio drop of the high-pressure turbine, the initial guess value of the pressure ratio drop of the low-pressure turbine, the initial guess value of the pressure ratio drop of the free turbine, and the initial guess value of the free turbine speed. Based on the zero-dimensional models of the components of the high-pressure compressor, combustion chamber, high-pressure turbine, low-pressure turbine, free turbine, and nozzle connected in sequence behind the low-pressure compressor, calculate the inlet and outlet section parameters of each component;

[0111] Engine common working balance equation construction module, which is used to construct the second to eighth balance equations according to the seven balance conditions of the flow continuity between the high-pressure compressor and the low-pressure compressor, the flow continuity between the combustion chamber and the high-pressure turbine, the power balance on the high-pressure shaft, the flow continuity between the high-pressure turbine and the low-pressure turbine, the power balance on the low-pressure shaft, the flow continuity between the low-pressure turbine and the free turbine, and the flow continuity between the free turbine and the nozzle;

[0112] Gear reducer power transfer calculation module, which is used to construct the ninth balance equation according to the power balance relationship that the shaft power output by the free turbine needs to satisfy the sum of the front propeller power and the rear propeller power calculated based on the three-dimensional lifting line model of the contra-rotating propeller fan;

[0113] Gear reducer torque transfer calculation module, which is used to calculate the sun shaft torque of the planetary gear reducer connected to it according to the shaft power and speed output by the free turbine, distribute the sun shaft torque to the front row propeller fan and the rear row propeller fan according to the connection relationship between the planetary gear reducer and the front row propeller fan and the rear row propeller fan, and construct the tenth and eleventh balance equations according to the balanced relationship between the distributed torque and the front propeller torque and the rear propeller torque calculated based on the three-dimensional lifting line model of the contra-rotating propeller fan;

[0114] Common working equation set solving module, which is used to select three of the above fourteen independent variables that need to be given initial guess values as control parameters, and solve the common working equation set composed of the above eleven balance equations by iterating the initial guess values of the remaining eleven independent variables. When the iteration converges, calculate the engine performance;

[0115] Wherein, the section parameters include one or more of flow rate, area, total temperature, total pressure, and total enthalpy.

[0116] In some alternative embodiments, the contra-rotating propeller fan and inlet duct aerodynamic coupling module includes:

[0117] Contra-rotating propeller fan axial average induced velocity calculation unit, which is used to determine the axial average induced velocity at the contra-rotating propeller fan according to the total thrust of the contra-rotating propeller fan;

[0118] An axial average velocity calculation unit of the air flow, which is used to calculate the axial average velocity of the air flow at the inlet of the inlet duct according to the distance between the contra-rotating propeller fan and the inlet of the inlet duct and the axial average induced velocity.

[0119] In some alternative embodiments, in the low-pressure compressor parameter calculation module, the outlet static pressures of the distorted low-pressure compressor and the non-distorted low-pressure compressor are calculated based on the inlet cross-section parameters of each of them, assuming that the inlet and outlet areas of the low-pressure compressor remain unchanged, and the outlet static pressures of each of them are calculated by the inlet areas in the inlet cross-section parameters of each of them.

[0120] In some alternative embodiments, in the common working equation set solving module, the three control parameters selected include the pitch angle of the front propeller, the pitch angle of the rear propeller, and the fuel supply amount of the combustion chamber.

[0121] In some alternative embodiments, in the common working equation set solving module, the common working equation set composed of the above eleven balance equations is solved by the Newton iteration method, and the Jacobian matrix constructed by the Newton iteration method is calculated in parallel through multi-threading.

[0122] As described above, the above are only the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A variable dimension numerical simulation method for an engine, characterized in that: include: Step S1, given an initial guess value of the front propeller speed, the front propeller pitch angle, the rear propeller speed, and the rear propeller pitch angle of the counter-rotating propeller fan, the total thrust, the front propeller power, the rear propeller power, the front propeller torque, and the rear propeller torque of the counter-rotating propeller fan are calculated based on a three-dimensional lift line model of the counter-rotating propeller fan; Step S2, determining the average axial velocity of the airflow at the inlet of the air inlet behind the counter-rotating propeller fan according to the total thrust of the counter-rotating propeller fan; Step S3, determining the cross-sectional parameters at the inlet of the air intake duct according to the average axial velocity of the airflow at the inlet of the air intake duct; Step S4, calculating the cross-sectional parameters at the inlet duct outlet according to the zero-dimensional model of the inlet duct; Step S5, dividing the airflow at the outlet of the inlet duct into two streams, one stream flows to the distorted low-pressure compressor, and the other stream flows to the undistorted low-pressure compressor, determining the cross-sectional parameters at the inlet of the distorted low-pressure compressor according to the given pressure distortion index, and then determining the cross-sectional parameters at the outlet of the distorted low-pressure compressor according to the given initial guess value of the pressure ratio of the distorted low-pressure compressor and the initial guess value of the low-pressure compressor speed, and at the same time, determining the cross-sectional parameters at the outlet of the undistorted low-pressure compressor according to the given initial guess value of the pressure ratio of the undistorted low-pressure compressor and the initial guess value of the low-pressure compressor speed, mixing the airflow at the outlet of the distorted low-pressure compressor with the airflow at the outlet of the undistorted low-pressure compressor, calculating the cross-sectional parameters at the outlet of the low-pressure compressor through a mixing model, and constructing a first equilibrium equation according to the static pressure equilibrium conditions of the outlet of the distorted low-pressure compressor and the outlet of the undistorted low-pressure compressor; Step S6, given the initial guess value of the high-pressure compressor pressure ratio, the initial guess value of the high-pressure compressor speed, the initial guess value of the combustion chamber fuel supply, the initial guess value of the high-pressure turbine pressure ratio, the initial guess value of the low-pressure turbine pressure ratio, the initial guess value of the free turbine pressure ratio and the initial guess value of the free turbine speed, based on the zero-dimensional model of the high-pressure compressor, the combustion chamber, the high-pressure turbine, the low-pressure turbine, the free turbine, and the tail nozzle components connected in sequence behind the low-pressure compressor, calculate the inlet and outlet cross-sectional parameters of each component; Step S7, constructing the second to eighth balance equations according to the seven balance conditions of flow continuity between the high-pressure compressor and the low-pressure compressor, flow continuity between the combustion chamber and the high-pressure turbine, power balance on the high-pressure shaft, flow continuity between the high-pressure turbine and the low-pressure turbine, power balance on the low-pressure shaft, flow continuity between the low-pressure turbine and the free turbine, and flow continuity between the free turbine and the tail nozzle; Step S8, constructing a ninth balance equation according to the power balance relationship that needs to be satisfied between the shaft power output by the free turbine and the sum of the front propeller power and the rear propeller power calculated based on the three-dimensional lift line model of the counter-rotating propeller fan; Step S9, calculating the sun shaft torque of the planetary gear reducer connected to the free turbine according to the shaft power and speed outputted by the free turbine, distributing the sun shaft torque to the front propeller fan and the rear propeller fan according to the connection relationship between the planetary gear reducer and the front propeller fan and the rear propeller fan, and constructing the tenth balance equation and the eleventh balance equation according to the relationship between the distributed torque and the front propeller torque and the rear propeller torque calculated based on the three-dimensional lift line model of the counter-rotating propeller fan; Step S10, selecting three as control parameters from the fourteen independent variables that need to be given initial guess values, solving the common working equation group consisting of the eleven equilibrium equations constructed above by iterating the initial guess values ​​of the remaining eleven independent variables, and calculating the engine performance when the iteration converges; The cross-sectional parameters include one or more of flow rate, area, total temperature, total pressure and total enthalpy.

2. The engine variable dimension numerical simulation method according to claim 1, characterized in that: Step S2 further comprises: Step S21, determining the average induced axial velocity at the counter-rotating propeller according to the total thrust of the counter-rotating propeller; Step S22, calculating the average axial velocity of the airflow at the inlet of the air inlet according to the distance between the counter-rotating propeller fan and the inlet of the air inlet and the average axial induced velocity.

3. The engine variable dimension numerical simulation method according to claim 1, characterized in that: In step S5, the outlet static pressures of the distorted low-pressure compressor and the non-distorted low-pressure compressor are calculated according to their respective inlet cross-sectional parameters and based on the assumption that the inlet and outlet areas of the low-pressure compressors remain unchanged, and according to the inlet areas in their respective inlet cross-sectional parameters.

4. The engine variable dimension numerical simulation method according to claim 1, characterized in that: In step S10, the three control parameters selected include the front propeller pitch angle, the rear propeller pitch angle and the fuel supply to the combustion chamber.

5. The engine variable dimension numerical simulation method according to claim 1, characterized in that: In step S10, the common working equation group consisting of the eleven equilibrium equations constructed above is solved by Newton's iteration method, and the Jacobian matrix constructed by the Newton's iteration method is calculated in parallel by multi-threading.

6. An engine variable dimension numerical simulation device, characterized in that: include: A contra-rotating propeller fan parameter calculation module is used to calculate the total thrust, front propeller power, rear propeller power, front propeller torque and rear propeller torque of the contra-rotating propeller fan based on a three-dimensional lift line model of the contra-rotating propeller fan given an initial guess of the front propeller speed, the front propeller pitch angle, the rear propeller speed and the rear propeller pitch angle; The contra-rotating propeller fan and the air inlet aerodynamic coupling module is used to determine the axial average velocity of the airflow at the inlet inlet behind the contra-rotating propeller fan according to the total thrust of the contra-rotating propeller fan, and then determine the cross-sectional parameters at the inlet inlet according to the axial average velocity of the airflow at the inlet inlet; An intake duct parameter calculation module, used to calculate the cross-sectional parameters at the intake duct outlet according to the intake duct zero-dimensional model; A low-pressure compressor parameter calculation module is used to divide the airflow at the inlet outlet into two streams, one stream flows to the distorted low-pressure compressor, and the other stream flows to the undistorted low-pressure compressor, determine the cross-sectional parameters at the inlet of the distorted low-pressure compressor according to a given pressure distortion index, and then determine the cross-sectional parameters at the outlet of the distorted low-pressure compressor according to a given initial guess value of the pressure ratio of the distorted low-pressure compressor and an initial guess value of the low-pressure compressor speed, and at the same time, determine the cross-sectional parameters at the outlet of the undistorted low-pressure compressor according to a given initial guess value of the pressure ratio of the undistorted low-pressure compressor and an initial guess value of the low-pressure compressor speed, mix the airflow at the outlet of the distorted low-pressure compressor with the airflow at the outlet of the undistorted low-pressure compressor, calculate the cross-sectional parameters at the outlet of the low-pressure compressor through a mixing model, and construct a first balance equation according to the static pressure balance conditions of the outlet of the distorted low-pressure compressor and the outlet of the undistorted low-pressure compressor; The module for calculating parameters of other components is used to calculate the inlet and outlet cross-sectional parameters of each component based on the zero-dimensional model of the high-pressure compressor, combustion chamber, high-pressure turbine, free turbine, and tail nozzle components connected in sequence behind the low-pressure compressor, given the initial guess values ​​of the high-pressure compressor pressure ratio, the initial guess value of the high-pressure compressor speed, the initial guess value of the combustion chamber fuel supply, the initial guess value of the high-pressure turbine pressure ratio, the initial guess value of the low-pressure turbine pressure ratio, and the initial guess value of the free turbine speed; The engine working together balance equation construction module is used to construct the second to eighth balance equations according to the seven balance conditions of flow continuity between the high-pressure compressor and the low-pressure compressor, flow continuity between the combustion chamber and the high-pressure turbine, power balance on the high-pressure shaft, flow continuity between the high-pressure turbine and the low-pressure turbine, power balance on the low-pressure shaft, flow continuity between the low-pressure turbine and the free turbine, and flow continuity between the free turbine and the tail nozzle; The gear reducer power transfer calculation module is used to construct the ninth balance equation according to the power balance relationship that needs to be satisfied between the shaft power output by the free turbine and the sum of the front propeller power and the rear propeller power calculated based on the three-dimensional lift line model of the counter-rotating propeller fan; a gear reducer torque transmission calculation module, for calculating the sun shaft torque of the planetary gear reducer connected thereto according to the shaft power and speed output by the free turbine, distributing the sun shaft torque to the front propellers and the rear propellers according to the connection relationship between the planetary gear reducer and the front propellers and the rear propellers, and constructing the tenth balance equation and the eleventh balance equation according to the relationship between the distributed torque and the front propeller torque and the rear propeller torque calculated based on the three-dimensional lift line model of the counter-rotating propellers; A common working equation group solving module is used to select three as control parameters from the above fourteen independent variables that need to be given initial guess values, solve the common working equation group consisting of the above eleven equilibrium equations by iterating the initial guess values ​​of the remaining eleven independent variables, and calculate the engine performance when the iteration converges; The cross-sectional parameters include one or more of flow rate, area, total temperature, total pressure and total enthalpy.

7. The engine variable dimension numerical simulation device according to claim 6, characterized in that: The counter-rotating propeller fan and the air inlet aerodynamic coupling module comprises: A counter-rotating propeller axial average induced speed calculation unit, used to determine the counter-rotating propeller axial average induced speed at the counter-rotating propeller according to the total thrust of the counter-rotating propeller; The airflow axial average velocity calculation unit is used to calculate the axial average velocity of the airflow at the inlet of the air inlet according to the distance between the counter-rotating propeller fan and the inlet of the air inlet and the axial average induced velocity.

8. The engine variable dimension numerical simulation device according to claim 6, characterized in that: In the low-pressure compressor parameter calculation module, the outlet static pressure of the distorted low-pressure compressor and the non-distorted low-pressure compressor is calculated based on their respective inlet cross-sectional parameters and the assumption that the inlet and outlet areas of the low-pressure compressor are constant, and the respective outlet static pressures are calculated based on the inlet areas in their respective inlet cross-sectional parameters.

9. The engine variable dimension numerical simulation device according to claim 6, characterized in that: In the joint working equation group solving module, the three selected control parameters include the front propeller pitch angle, the rear propeller pitch angle and the combustion chamber fuel supply.

10. The engine variable dimension numerical simulation device according to claim 6, characterized in that: In the common working equation group solving module, the common working equation group consisting of the eleven equilibrium equations constructed above is solved by Newton iteration method, and the Jacobian matrix constructed by Newton iteration method is calculated in parallel by multi-threading.

Images