Method, device, equipment and medium for determining boundary conditions of aircraft engine inlet

Abstract

The present application discloses a method, apparatus, device, and medium for determining boundary conditions at an aircraft engine inlet, relating to the field of fluid mechanics. The method comprises: during computational fluid dynamics numerical simulation of an aircraft, collecting air flow rates from each grid surface at the engine inlet boundary to determine the current actual flow rate at the engine inlet; determining a critical specific flow density based on stagnation point information in the current flow field, and determining a target velocity for the grid surface based on the critical specific flow density, target flow rate, and current actual flow rate; determining the local static pressure of the grid surface based on the critical velocity and target velocity, determining whether the gas flow corresponding to each grid surface is supersonic, and determining a target pressure value for the grid surface based on the judgment result and the local static pressure; and determining target density and target velocity component information for the grid surface based on the body center value of the flow field unit to determine the target boundary conditions. The present application can efficiently and accurately determine the boundary conditions of an aircraft engine inlet and improve robustness.

Description

Technical Field

[0001] The present invention relates to the field of fluid mechanics, and in particular to a method, device, equipment and medium for determining boundary conditions of an aircraft engine inlet. Background Art

[0002] The engine inlet boundary condition is a type of boundary condition in CFD (Computational Fluid Dynamics) numerical simulations. It is usually used for flow field calculations at the inlet of an aircraft engine (such as the integrated flow field simulation of the internal and external flows of the entire aircraft with power) to avoid the difficulties brought by directly simulating the engine itself.

[0003] Figure 1 This is a schematic diagram of the calculated flow field. The right portion of the figure represents the engine's intake duct, and the grid line on the far right represents the engine inlet boundary surface. Engine inlet boundary conditions are typically determined and set using methods such as fixed backpressure, fixed velocity, or fixed flow. However, existing methods for determining engine inlet boundary conditions lack accuracy and fail to account for abnormal conditions such as supersonic flow patterns that may arise during the calculation process. This results in poor robustness and negatively impacts the stability and convergence of the flow field solution. Summary of the Invention

[0004] In view of this, the present invention aims to provide a method, apparatus, device, and medium for determining boundary conditions at an aircraft engine inlet. These methods can efficiently and accurately determine the boundary conditions at an aircraft engine inlet, while also taking into account possible abnormal conditions such as supersonic flow patterns. This improves robustness, thereby ensuring accurate simulation of the real physical domain through CFD numerical simulation and ensuring stability and convergence when solving the flow field in the real physical domain. The specific scheme is as follows:

[0005] In a first aspect, the present application provides a method for determining boundary conditions of an aircraft engine inlet, comprising:

[0006] During a computational fluid dynamics numerical simulation of an aircraft, collecting air flow rates on each grid surface of an engine inlet boundary of the aircraft to determine a current actual flow rate of the engine inlet;

[0007] Determining a critical specific flow density based on a stagnation point density and a stagnation point sound velocity in a current flow field, and determining a target velocity corresponding to each of the grid surfaces based on the critical specific flow density, a target flow corresponding to the engine inlet, and a current actual flow;

[0008] Determining a local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds, and determining whether the gas flow corresponding to each of the grid surfaces is supersonic, so as to determine a target pressure value corresponding to each of the grid surfaces based on the corresponding determination result and the local static pressure;

[0009] Extrapolation is performed based on the center-of-body value of the flow field unit to determine the target density and target velocity component information corresponding to each of the mesh surfaces, so as to determine the target boundary conditions corresponding to the engine inlet boundary; the target boundary conditions include the target pressure value, the target density and the target velocity component information of each of the mesh surfaces.

[0010] Optionally, collecting air flow on each grid surface at the boundary of the engine inlet of the aircraft to determine the current actual flow at the engine inlet includes:

[0011] After any computational fluid dynamics numerical iteration is completed, the body center value of the flow field unit in the current flow field is obtained; the body center value includes the flow field density value, pressure value and velocity components in the x, y and z directions in the spatial coordinate system at the body center;

[0012] For each mesh surface at the engine inlet boundary of the aircraft, the density and velocity of the corresponding mesh surface are determined based on the body center value of the corresponding flow field unit, and the area of ​​each mesh surface is obtained; the velocity is the velocity perpendicular to the mesh surface;

[0013] The current actual flow rate of the engine inlet is determined based on the density, the velocity, the area corresponding to each mesh surface and the total number of mesh surfaces.

[0014] Optionally, determining the critical specific flow density based on the stagnation point density and the stagnation point sound speed in the current flow field includes:

[0015] According to the definition of stagnation point, the stagnation point density is determined by combining the isentropic relation of calorimetric perfect gas and specific heat capacity;

[0016] The critical specific flow density is determined based on the critical velocity, the specific heat capacity, the stagnation point density, and the stagnation point sound velocity; the critical velocity is the velocity at which the gas flow on the grid surface becomes congested.

[0017] Optionally, determining the target speed corresponding to each grid surface based on the critical specific flow density, the target flow corresponding to the engine inlet, and the current actual flow includes:

[0018] determining a target flow ratio based on a target flow corresponding to the engine inlet and a current actual flow;

[0019] determining a current specific flow density of each of the grid surfaces based on the density and the velocity of each of the grid surfaces;

[0020] Adjusting the current specific flow density of each of the grid surfaces based on the target flow ratio to determine an adjusted specific flow density corresponding to each of the grid surfaces;

[0021] By comparing the magnitudes of the adjusted specific flow density and the critical specific flow density respectively, a comparison result corresponding to each of the grid surfaces is obtained;

[0022] If any of the comparison results indicates that the adjusted specific flow density is not less than the critical specific flow density, the critical specific flow density is used as the target specific flow density of the corresponding grid surface, and the critical speed is used as the target speed of the corresponding grid surface;

[0023] If any of the comparison results indicates that the adjusted specific flow density is less than the critical specific flow density, the preset formula is iteratively solved based on the Newton iteration method until the preset iterative solution condition is met, and the target speed of the corresponding grid surface is determined.

[0024] Optionally, determining the local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds includes:

[0025] Determine the ratio between the target speed and the critical speed corresponding to each of the grid surfaces by comparison, so as to determine the target Laval number corresponding to each of the grid surfaces;

[0026] The local static pressure corresponding to each of the grid surfaces is determined based on the target Laval number, the specific heat capacity, and the isentropic relationship.

[0027] Optionally, judging whether the gas flow corresponding to each of the grid surfaces is supersonic, and determining the target pressure value corresponding to each of the grid surfaces based on the corresponding judgment result and the local static pressure, includes:

[0028] determining an average pressure value based on the local static pressure and the area corresponding to each of the grid surfaces;

[0029] For any of the grid surfaces, determining whether the corresponding target Laval number is greater than a preset threshold to obtain a Laval number determination result;

[0030] If the Laval number determination result indicates that the gas flow on the current grid surface is greater than the preset threshold, the gas flow on the current grid surface is determined to be supersonic, and the pressure value of the corresponding flow field unit is extrapolated to the current grid surface to determine the corresponding target pressure value;

[0031] If the Laval number determination result indicates that the Laval number is not greater than the preset threshold, it is determined that the gas flow on the current grid surface is subsonic, and the average pressure value is used as the target pressure value on the current grid surface.

[0032] Optionally, the extrapolation based on the body center value of the flow field unit to determine the target density and target velocity component information corresponding to each of the grid surfaces to determine the target boundary condition corresponding to the engine inlet boundary includes:

[0033] Obtaining the body center value of the flow field unit corresponding to each of the grid surfaces in the current flow field;

[0034] For any of the mesh surfaces, the flow field density value in the corresponding body center value and the velocity components in the x, y, and z directions in the spatial coordinate system are extrapolated onto the corresponding current mesh surface to determine the corresponding target density and target velocity component information;

[0035] The target density, the target velocity component information, and the target pressure value of each of the grid surfaces are used as target boundary conditions corresponding to the engine inlet boundary, so as to complete a corresponding engine inlet boundary condition setting operation based on the target boundary conditions.

[0036] In a second aspect, the present application provides a device for determining boundary conditions of an aircraft engine inlet, comprising:

[0037] a flow acquisition module, configured to collect air flow on each grid surface at the boundary of the engine inlet of the aircraft during a computational fluid dynamics numerical simulation of the aircraft, so as to determine a current actual flow at the engine inlet;

[0038] a speed determination module, configured to determine a critical specific flow density based on a stagnation point density and a stagnation point sound speed in a current flow field, and determine a target speed corresponding to each of the grid surfaces based on the critical specific flow density, a target flow corresponding to the engine inlet, and a current actual flow;

[0039] a target pressure value determination module, configured to determine a local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds, and determine a target pressure value corresponding to each of the grid surfaces based on the corresponding determination result and the local static pressure by judging whether the gas flow corresponding to each of the grid surfaces is supersonic;

[0040] A boundary condition determination module is used to perform extrapolation based on the center-of-body value of the flow field unit to determine the target density and target velocity component information corresponding to each of the mesh surfaces, so as to determine the target boundary condition corresponding to the engine inlet boundary; the target boundary condition includes the target pressure value, the target density and the target velocity component information of each of the mesh surfaces.

[0041] In a third aspect, the present application provides an electronic device, comprising:

[0042] Memory, used to store computer programs;

[0043] The processor is configured to execute the computer program to implement the steps of the aforementioned method for determining the boundary conditions of an aircraft engine inlet.

[0044] In a fourth aspect, the present application provides a computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the steps of the aforementioned method for determining the boundary conditions of an aircraft engine inlet.

[0045] It can be seen that in the present application, in the process of performing computational fluid dynamics numerical simulation on the aircraft, the air flow rate of each grid surface of the engine inlet boundary of the aircraft is collected to determine the current actual flow rate of the engine inlet; the critical specific flow density is determined based on the stagnation point density and the stagnation point sound speed in the current flow field, and the target speed corresponding to each grid surface is determined based on the critical specific flow density, the target flow corresponding to the engine inlet and the current actual flow rate; the local static pressure corresponding to each grid surface is determined based on the critical speed and each target speed, and by judging whether the gas flow corresponding to each grid surface is supersonic, the target pressure value corresponding to each grid surface is determined based on the corresponding judgment result and the local static pressure; extrapolation is performed based on the body center value of the flow field unit to determine the target density and target velocity component information corresponding to each grid surface to determine the target boundary condition corresponding to the engine inlet boundary; the target boundary condition includes the target pressure value, the target density and the target velocity component information of each grid surface. Specifically, during the computational fluid dynamics (CFD) numerical simulation of an aircraft, the present application first collects the air flow rate for each mesh surface at the aircraft's engine inlet boundary. The target velocity for each mesh surface is then determined based on the current actual flow rate, critical specific flow density, and target flow rate at the engine inlet. The corresponding local static pressure is then determined based on the target velocity. The target pressure for each mesh surface is determined by determining whether the gas flow at the mesh surface is supersonic, combined with the local static pressure. The target density and target velocity component information for each mesh surface are then extrapolated based on the body center values ​​of the flow field cells. In other words, the static pressure for each mesh surface at the engine inlet boundary is adjusted based on the set fixed flow rate and the target flow rate so that the flow rate at the mesh surface meets the target flow rate. This allows for efficient and accurate determination of the aircraft's engine inlet boundary conditions while also accounting for possible anomalies such as supersonic flow regimes. This improves robustness, ensures accurate simulation of the real physical domain through CFD numerical simulation, and ensures stability and convergence when solving the flow field in the real physical domain. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0047] Figure 1 A schematic diagram of a computational flow field including an aircraft engine inlet boundary provided in this application;

[0048] Figure 2 A flow chart of a method for determining boundary conditions of an aircraft engine inlet provided in this application;

[0049] Figure 3 A schematic cross-sectional view of an aircraft engine inlet boundary unit provided in this application;

[0050] Figure 4 A schematic diagram of the structure of a device for determining boundary conditions at an aircraft engine inlet provided in this application;

[0051] Figure 5 This is a structural diagram of an electronic device provided in this application. DETAILED DESCRIPTION

[0052] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0053] Engine inlet boundary conditions are typically determined and set using methods such as fixed backpressure, fixed velocity, or fixed flow. However, existing methods for determining engine inlet boundary conditions have low accuracy and fail to account for abnormal conditions such as supersonic flow regimes that may arise during the calculation process. This results in poor robustness and negatively impacts the stability and convergence of the flow field solution.

[0054] To this end, the present application provides a solution for determining the boundary conditions of an aircraft engine inlet, which can efficiently and accurately determine the boundary conditions of the aircraft engine inlet, while taking into account abnormal conditions such as supersonic flow states that may occur, thereby improving robustness.

[0055] See also Figure 2As shown, an embodiment of the present invention discloses a method for determining boundary conditions of an aircraft engine inlet, comprising:

[0056] Step S11 : During computational fluid dynamics numerical simulation of an aircraft, air flow rates are collected on each grid surface at the boundary of an engine inlet of the aircraft to determine a current actual flow rate at the engine inlet.

[0057] Specifically, in this embodiment, in the process of numerical simulation of computational fluid dynamics of the aircraft, in order to accurately set the boundary conditions, the current actual flow rate of the aircraft engine inlet is first obtained (available Represented), that is, after any computational fluid dynamics numerical iteration is completed, the body center value of the flow field unit in the current flow field is obtained; the body center value includes the flow field density value, pressure value and velocity components in the x, y and z directions in the spatial coordinate system at the body center; for each grid surface at the engine inlet boundary of the aircraft, the density and velocity of the corresponding grid surface are determined based on the body center value of the corresponding flow field unit, and the area of ​​each grid surface is obtained; the velocity is the velocity perpendicular to the grid surface; the current actual flow rate at the engine inlet is determined based on the density, velocity and area corresponding to each grid surface and the total number of grid surfaces. In other words, this embodiment can obtain the body center value of the flow field unit after each numerical iteration step of CFD is completed, combined with Figure 3 As shown, B represents the boundary surface, x represents a center point, and the body center is the body center of the flow field unit c to which the i-th grid surface (i.e., boundary surface) belongs. The body center value includes the flow field density value , the velocity component in the x direction , the velocity component in the y direction , the velocity component in the z direction And pressure values. It is understandable that the center of mass value of each flow field unit may be different. For each grid surface of the engine inlet boundary, the air flow is collected to obtain the current actual flow rate, as shown in the following formula:

[0058] .

[0059] Where i represents the i-th boundary surface; The number of all boundary surfaces representing the engine inlet boundary, that is, the total number of mesh faces; is the density of the i-th boundary surface; is the velocity perpendicular to the i-th boundary surface; is the area of ​​the i-th boundary surface. and Specifically, it is calculated by taking the center value of the flow field unit c to which the i-th boundary surface belongs.

[0060] Step S12: determining a critical specific flow density based on the stagnation point density and the stagnation point sound speed in the current flow field, and determining a target velocity corresponding to each of the grid surfaces based on the critical specific flow density, the target flow corresponding to the engine inlet, and the current actual flow.

[0061] In this embodiment, after determining the current actual flow rate at the engine inlet, the target velocity for each grid surface is determined based on the target flow rate. To determine the target velocity, the critical specific flow density is first determined. That is, the stagnation density is first determined based on the stagnation point definition and in combination with the isentropic relationship of the calorimetric complete gas and the specific heat capacity. The critical specific flow density is then determined based on the critical velocity, the specific heat capacity, the stagnation point density, and the stagnation point sound velocity. The critical velocity is the velocity at which the gas flow on the grid surface becomes congested. It is understood that for any grid surface, the specific flow density q is calculated based on the isentropic relationship of the calorimetric complete gas as shown below:

[0062] .

[0063] Where, is the stagnation point density, is the stagnation speed of sound, is the specific heat capacity, is the velocity perpendicular to the boundary surface, When the velocity is the critical velocity, the specific flow density reaches its maximum value. The flow at this time is called "congestion". The specific flow density at this time is called the critical specific flow density (available ), as shown below:

[0064] .

[0065] Where, is the critical density, is the critical speed, and the values ​​of these two can be obtained from known quantities through the isentropic relationship.

[0066] At the same time, it is also necessary to determine the specific flow density of each grid surface at the target flow rate, and then determine the target speed of each grid surface in combination with the critical specific flow density, that is, determine the target flow ratio based on the target flow rate corresponding to the engine inlet and the current actual flow rate; determine the current specific flow density of each grid surface based on the density and the speed of each grid surface; adjust the current specific flow density of each grid surface based on the target flow ratio to determine the adjusted specific flow density corresponding to each grid surface; by comparing the size of each adjusted specific flow density with the critical specific flow density, a comparison result corresponding to each grid surface is obtained; if any of the comparison results shows that the adjusted specific flow density is not less than the critical specific flow density, then the critical specific flow density is used as the target specific flow density of the corresponding grid surface, and the critical speed is used as the target speed of the corresponding grid surface; if any of the comparison results shows that the adjusted specific flow density is less than the critical specific flow density, then iteratively solve the preset formula based on the Newton iteration method until the preset iterative solution condition is met and the target speed of the corresponding grid surface is determined. It is understood that there is no particular order in which to determine the critical specific flow density and the adjusted specific flow density. Specific flow density, also known as density flow, represents the mass flow rate passing through a unit area per unit time.

[0067] It is important to understand that the target flow rate is The calculation formula is as follows:

[0068] .

[0069] Where, is the target traffic. Then, use The current specific flow density for each boundary surface Adjust the specific flow density after adjustment. As shown in the following formula:

[0070] .

[0071] Afterwards, the adjusted specific flow density To restrict, if Not less than (represents the critical specific flow density corresponding to each grid surface i), then the specific flow density of the grid surface is limited to , and let the target speed of the grid surface be the critical speed On the contrary, if Less than , then use the Newton iteration method to solve the following formula to obtain the target velocity of the grid surface, and select any grid surface angle to describe it:

[0072] .

[0073] The specific iterative process is as follows: The initial value can be assigned to 0.0, k represents the kth iteration, represents the speed value obtained in the kth round of iteration, Indicates the speed value obtained in the k+1th round of iteration:

[0074] .

[0075] and its derivatives As shown in the following formula:

[0076] .

[0077] In the formula represents the adjusted specific flow density of the boundary surface. To prevent division by zero, Restricted to more than a small amount, e.g. . Regarding the termination of iteration, when When the absolute value of is less than 1.0e-8 or the number of iterations k reaches 200, the iteration is stopped and the target speed is obtained. The speed obtained by the iteration is limited to no more than the critical speed. .

[0078] Step S13: determining the local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds, and determining whether the gas flow corresponding to each of the grid surfaces is supersonic, so as to determine the target pressure value corresponding to each of the grid surfaces based on the corresponding judgment result and the local static pressure.

[0079] In this embodiment, after determining the target velocity of each mesh surface, the target velocity will be used to determine the target pressure value. To determine the target pressure value, it is necessary to first determine the local static pressure, that is, by comparing and determining the ratio between the target velocity and the critical velocity corresponding to each mesh surface, to determine the target Laval number corresponding to each mesh surface; based on the target Laval number, the specific heat capacity, and the isentropic relationship, the local static pressure corresponding to each mesh surface is determined. Specifically, according to the target velocity of the boundary surface (available Expressed) and critical speed calculation Laval number , as shown below:

[0080] .

[0081] Then, according to the isentropic relationship, the local static pressure on the boundary surface can be obtained , as shown below:

[0082] .

[0083] Where, is the stagnation pressure on the boundary surface, generally called the total pressure.

[0084] Furthermore, after obtaining the local static pressure, the target pressure value can be determined by judgment. That is, the average pressure value is determined based on the local static pressure and the area corresponding to each grid surface; for any grid surface, it is determined whether the corresponding target Laval number is greater than the preset threshold value to obtain the Laval number judgment result; if the Laval number judgment result shows that it is greater than the preset threshold value, it is determined that the gas flow of the current grid surface is supersonic, and the pressure value of the corresponding flow field unit is extrapolated to the current grid surface to determine the corresponding target pressure value; if the Laval number judgment result shows that it is not greater than the preset threshold value, it is determined that the gas flow of the current grid surface is subsonic, and the average pressure value is used as the target pressure value of the current grid surface. Specifically, the average value of the boundary surface pressure is calculated. , as shown below:

[0085] .

[0086] Where, is the local static pressure of the i-th boundary surface determined by the above steps. Then, the pressure value of the boundary surface is calculated according to the target Laval number. >1, then the flow on the boundary surface is considered to be supersonic, and the pressure value of the flow field unit to which the boundary surface belongs is The target pressure value of the boundary surface is obtained by extrapolating the unit center to the boundary surface. ,Right now Otherwise, the flow on the boundary surface is considered to be subsonic, and the target pressure value of the boundary surface is specified as the calculated pressure average value, that is, Among them, it can be understood that the pressure value of each flow field unit Maybe it's different.

[0087] Step S14: extrapolate based on the center-of-body value of the flow field unit to determine the target density and target velocity component information corresponding to each of the mesh surfaces, so as to determine the target boundary conditions corresponding to the engine inlet boundary; the target boundary conditions include the target pressure value, the target density and the target velocity component information of each of the mesh surfaces.

[0088] In this embodiment, to determine the density and velocity components of each mesh surface at the target flow rate, the body center values ​​of the flow field units corresponding to each mesh surface in the current flow field are first obtained. Then, for each mesh surface, the flow field density value and the velocity components in the x, y, and z directions of the spatial coordinate system from the corresponding body center values ​​are extrapolated onto the corresponding current mesh surface to determine the corresponding target density and target velocity component information. The target density, target velocity component information, and target pressure value of each mesh surface are used as the target boundary conditions corresponding to the engine inlet boundary, and the corresponding engine inlet boundary condition setting operation is completed based on the target boundary conditions. The relevant expressions are shown below.

[0089] .

[0090] Where, represents the target density of the boundary surface, Indicates the velocity component in the x direction of the target velocity component information of the boundary surface, Indicates the velocity component in the y direction of the target velocity component information of the boundary surface, Indicates the velocity component in the z direction of the target velocity component information of the boundary surface, Represents the unit body center flow field density value of the flow field unit, represents the velocity component of the unit body center in the x direction, It represents the velocity component of the unit body center in the y direction of the flow field unit, In other words, the density and velocity components of each boundary surface are obtained by extrapolating the density and velocity components of the flow field unit to which it belongs.

[0091] In summary, this embodiment describes an aerodynamic analysis method for determining the engine inlet boundary conditions, based on a given target flow rate. , convert the average back pressure of the boundary surface , and extrapolating other flow field variables (density and velocity components) to obtain a complete boundary condition. This approach adjusts the static pressure at the boundary surface to ensure that the flow rate at the boundary surface meets the given target value. It also takes into account abnormal conditions such as local congestion and supersonic flow patterns that may arise during the calculation process, achieving the advantages of both accuracy and robustness.

[0092] As can be seen, during the computational fluid dynamics (CFD) numerical simulation of an aircraft, the present application first collects the air flow rate for each mesh surface at the aircraft's engine inlet boundary. The target velocity for each mesh surface is then determined based on the current actual flow rate, critical specific flow density, and target flow rate at the engine inlet. The corresponding local static pressure is then determined based on the target velocity. The target pressure for each mesh surface is determined by determining whether the gas flow at the mesh surface is supersonic, combined with the local static pressure. The target density and target velocity component information for each mesh surface is then extrapolated based on the body center values ​​of the flow field cells. In other words, the static pressure for each mesh surface at the engine inlet boundary is adjusted based on the set fixed flow rate and the target flow rate so that the flow rate at the mesh surface meets the target flow rate. This allows for efficient and accurate determination of the aircraft's engine inlet boundary conditions while also accounting for possible abnormalities such as supersonic flow regimes. This improves robustness, ensures accurate simulation of the real physical domain through CFD numerical simulation, and ensures stability and convergence when solving the flow field in the real physical domain.

[0093] See also Figure 4 As shown, the embodiment of the present application also discloses a device for determining boundary conditions of an aircraft engine inlet, including:

[0094] The flow collection module 11 is used to collect air flow on each grid surface of the engine inlet boundary of the aircraft during the computational fluid dynamics numerical simulation of the aircraft to determine the current actual flow rate of the engine inlet;

[0095] a speed determination module 12, configured to determine a critical specific flow density based on a stagnation point density and a stagnation point sound speed in a current flow field, and to determine a target speed corresponding to each of the grid surfaces based on the critical specific flow density, a target flow corresponding to the engine inlet, and a current actual flow;

[0096] a target pressure value determining module 13, configured to determine a local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds, and to determine a target pressure value corresponding to each of the grid surfaces based on the corresponding determination result and the local static pressure by judging whether the gas flow corresponding to each of the grid surfaces is supersonic;

[0097] The boundary condition determination module 14 is used to perform extrapolation based on the center-of-body value of the flow field unit to determine the target density and target velocity component information corresponding to each of the mesh surfaces, so as to determine the target boundary conditions corresponding to the engine inlet boundary; the target boundary conditions include the target pressure value, the target density and the target velocity component information of each of the mesh surfaces.

[0098] As can be seen, during the computational fluid dynamics (CFD) numerical simulation of an aircraft, the present application first collects the air flow rate for each mesh surface at the aircraft's engine inlet boundary. The target velocity for each mesh surface is then determined based on the current actual flow rate, critical specific flow density, and target flow rate at the engine inlet. The corresponding local static pressure is then determined based on the target velocity. The target pressure for each mesh surface is determined by determining whether the gas flow at the mesh surface is supersonic, combined with the local static pressure. The target density and target velocity component information for each mesh surface is then extrapolated based on the body center values ​​of the flow field cells. In other words, the static pressure for each mesh surface at the engine inlet boundary is adjusted based on the set fixed flow rate and the target flow rate so that the flow rate at the mesh surface meets the target flow rate. This allows for efficient and accurate determination of the aircraft's engine inlet boundary conditions while also accounting for possible abnormalities such as supersonic flow regimes. This improves robustness, ensures accurate simulation of the real physical domain through CFD numerical simulation, and ensures stability and convergence when solving the flow field in the real physical domain.

[0099] In some specific embodiments, the traffic collection module 11 may specifically include:

[0100] A body center value acquisition unit is used to obtain the body center value of the flow field unit in the current flow field after any computational fluid dynamics numerical iteration is completed; the body center value includes the flow field density value, pressure value and velocity components in the x, y and z directions in the spatial coordinate system at the body center;

[0101] a mesh surface information acquisition unit, configured to determine, for each mesh surface at the engine inlet boundary of the aircraft, a density and a velocity of the corresponding mesh surface based on the body center value of the corresponding flow field unit, and to acquire an area of ​​each mesh surface; the velocity being a velocity perpendicular to the mesh surface;

[0102] The actual flow determination unit is used for determining the current actual flow of the engine inlet based on the density, the speed, the area corresponding to each grid surface and the total number of grid surfaces.

[0103] In some specific embodiments, the speed determination module 12 may specifically include:

[0104] A stagnation point density determination unit is used to determine the stagnation point density according to the stagnation point definition and in combination with the isentropic relationship and specific heat capacity of the calorimetric perfect gas;

[0105] The critical specific flow density determining unit is used to determine the critical specific flow density based on the critical velocity, the specific heat capacity, the stagnation point density and the stagnation point sound speed; the critical velocity is the velocity at which the gas flow on the grid surface becomes congested.

[0106] In some specific embodiments, the speed determination module 12 may specifically include:

[0107] a flow ratio determining unit, configured to determine a target flow ratio based on a target flow corresponding to the engine inlet and a current actual flow;

[0108] determining a current specific flow density of each of the grid surfaces based on the density and the velocity of each of the grid surfaces;

[0109] a specific flow density adjustment unit, configured to adjust a current specific flow density of each of the grid surfaces based on the target flow ratio to determine an adjusted specific flow density corresponding to each of the grid surfaces;

[0110] a flow density comparison unit, configured to compare the adjusted flow density with the critical flow density to obtain a comparison result corresponding to each grid surface;

[0111] a first speed determining unit configured to, if any of the comparison results indicates that the adjusted specific flow density is not less than the critical specific flow density, use the critical specific flow density as the target specific flow density of the corresponding grid surface, and use the critical speed as the target speed of the corresponding grid surface;

[0112] The second speed determination unit is used to iteratively solve the preset formula based on the Newton iteration method if any of the comparison results shows that the adjusted specific flow density is less than the critical specific flow density, and determine the target speed of the corresponding grid surface when the preset iterative solution condition is met.

[0113] In some specific embodiments, the target pressure value determination module 13 may specifically include:

[0114] a Laval number determining unit, configured to determine the ratio between the target speed and the critical speed corresponding to each of the grid surfaces by comparison, so as to determine the target Laval number corresponding to each of the grid surfaces;

[0115] A local static pressure determining unit is configured to determine the local static pressure corresponding to each of the grid surfaces based on the target Laval number, the specific heat capacity, and the isentropic relationship.

[0116] In some specific embodiments, the target pressure value determination module 13 may specifically include:

[0117] an average pressure value determining unit, configured to determine an average pressure value based on the local static pressure and the area corresponding to each of the grid surfaces;

[0118] a Laval number determination unit, configured to determine, for any of the grid surfaces, whether the corresponding target Laval number is greater than a preset threshold, so as to obtain a Laval number determination result;

[0119] a first pressure value determining unit, configured to, if the Laval number determination result indicates that the gas flow on the current grid surface is supersonic, extrapolate the pressure value of the corresponding flow field unit onto the current grid surface to determine a corresponding target pressure value;

[0120] The second pressure value determining unit is configured to determine that the gas flow on the current grid surface is subsonic if the Laval number judgment result indicates that the gas flow is not greater than the preset threshold, and use the average pressure value as the target pressure value on the current grid surface.

[0121] In some specific embodiments, the boundary condition determination module 14 may specifically include:

[0122] a body center value determination unit, configured to obtain the body center values ​​of the flow field units corresponding to the respective grid surfaces in the current flow field;

[0123] an extrapolation unit for determining corresponding target density and target velocity component information by extrapolating the flow field density value in the corresponding body center value and the velocity components in the x, y, and z directions in the spatial coordinate system onto the corresponding current grid surface for any of the grid surfaces;

[0124] The target boundary condition determination unit is used to use the target density, the target velocity component information and the target pressure value of each grid surface as the target boundary condition corresponding to the engine inlet boundary, so as to complete the corresponding engine inlet boundary condition setting operation based on the target boundary condition.

[0125] Furthermore, the embodiment of the present application also discloses an electronic device, Figure 5 This is a structural diagram of an electronic device 20 according to an exemplary embodiment. The content in the diagram should not be considered as any limitation to the scope of application of the present application.

[0126] Figure 5 This is a schematic diagram of the structure of an electronic device 20 provided in an embodiment of the present application. The electronic device 20 may specifically include: at least one processor 21, at least one memory 22, a power supply 23, a communication interface 24, an input / output interface 25, and a communication bus 26. The memory 22 is used to store a computer program, which is loaded and executed by the processor 21 to implement the relevant steps of the method for determining boundary conditions at an aircraft engine inlet disclosed in any of the aforementioned embodiments. Furthermore, the electronic device 20 in this embodiment may specifically be an electronic computer.

[0127] In this embodiment, the power supply 23 is used to provide operating voltage for each hardware device on the electronic device 20; the communication interface 24 can create a data transmission channel between the electronic device 20 and the external device. The communication protocol it follows is any communication protocol that can be applied to the technical solution of this application and is not specifically limited here; the input and output interface 25 is used to obtain external input data or output data to the outside world. Its specific interface type can be selected according to specific application needs and is not specifically limited here.

[0128] In addition, the memory 22, as a carrier for resource storage, can be a read-only memory, random access memory, disk or CD, etc. The resources stored thereon can include an operating system 221, a computer program 222, etc., and the storage method can be temporary storage or permanent storage.

[0129] The operating system 221 is used to manage and control the hardware devices and computer program 222 on the electronic device 20, and can be Windows Server, NetWare, Unix, Linux, etc. In addition to including a computer program capable of implementing the method for determining the boundary conditions of an aircraft engine inlet as disclosed in any of the aforementioned embodiments and executed by the electronic device 20, the computer program 222 may further include computer programs capable of performing other specific tasks.

[0130] Furthermore, this application discloses a computer-readable storage medium for storing a computer program. When executed by a processor, the computer program implements the aforementioned method for determining boundary conditions at an aircraft engine inlet. The specific steps of this method can be found in the corresponding sections disclosed in the aforementioned embodiments and will not be further elaborated here.

[0131] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from the other embodiments. Reference can be made to the descriptions of the identical or similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and the relevant parts can be referred to the descriptions of the methods.

[0132] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the above description has generally described the components and steps of each example according to their functions. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0133] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0134] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0135] The above is a detailed introduction to the technical solution provided by the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for determining boundary conditions of an aircraft engine inlet, characterized in that: include: During a computational fluid dynamics numerical simulation of an aircraft, collecting air flow rates on each grid surface of an engine inlet boundary of the aircraft to determine a current actual flow rate of the engine inlet; Determining a critical specific flow density based on a stagnation point density and a stagnation point sound velocity in a current flow field, and determining a target velocity corresponding to each of the grid surfaces based on the critical specific flow density, a target flow corresponding to the engine inlet, and a current actual flow; Determining a local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds, and determining whether the gas flow corresponding to each of the grid surfaces is supersonic, so as to determine a target pressure value corresponding to each of the grid surfaces based on the corresponding determination result and the local static pressure; Extrapolating based on the center-of-body value of the flow field unit to determine target density and target velocity component information corresponding to each of the mesh surfaces, so as to determine target boundary conditions corresponding to the engine inlet boundary; The target boundary conditions include the target pressure value, the target density, and the target velocity component information of each of the grid surfaces.

2. The method for determining the boundary conditions of an aircraft engine inlet according to claim 1, characterized in that: The collecting of air flow rates on each grid surface of the boundary of the engine inlet of the aircraft to determine the current actual flow rate of the engine inlet includes: After any computational fluid dynamics numerical iteration is completed, the body center value of the flow field unit in the current flow field is obtained; the body center value includes the flow field density value, pressure value and velocity components in the x, y and z directions in the spatial coordinate system at the body center; For each mesh surface at the engine inlet boundary of the aircraft, the density and velocity of the corresponding mesh surface are determined based on the body center value of the corresponding flow field unit, and the area of ​​each mesh surface is obtained; the velocity is the velocity perpendicular to the mesh surface; The current actual flow rate of the engine inlet is determined based on the density, the velocity, the area corresponding to each mesh surface and the total number of mesh surfaces.

3. The method for determining the boundary conditions of an aircraft engine inlet according to claim 2, characterized in that: The determining of the critical specific flow density based on the stagnation point density and the stagnation point sound velocity in the current flow field includes: According to the definition of stagnation point, the stagnation point density is determined by combining the isentropic relation of calorimetric perfect gas and specific heat capacity; The critical specific flow density is determined based on the critical velocity, the specific heat capacity, the stagnation point density, and the stagnation point sound speed; the critical velocity is the velocity at which the gas flow on the grid surface becomes congested.

4. The method for determining boundary conditions of an aircraft engine inlet according to claim 3, characterized in that: The determining of the target speed corresponding to each of the grid surfaces based on the critical specific flow density, the target flow corresponding to the engine inlet, and the current actual flow includes: determining a target flow ratio based on a target flow corresponding to the engine inlet and a current actual flow; determining a current specific flow density of each of the grid surfaces based on the density and the velocity of each of the grid surfaces; Adjusting the current specific flow density of each of the grid surfaces based on the target flow ratio to determine an adjusted specific flow density corresponding to each of the grid surfaces; By comparing the magnitudes of the adjusted specific flow density and the critical specific flow density respectively, a comparison result corresponding to each of the grid surfaces is obtained; If any of the comparison results indicates that the adjusted specific flow density is not less than the critical specific flow density, the critical specific flow density is used as the target specific flow density of the corresponding grid surface, and the critical speed is used as the target speed of the corresponding grid surface; If any of the comparison results indicates that the adjusted specific flow density is less than the critical specific flow density, the preset formula is iteratively solved based on the Newton iteration method until the preset iterative solution condition is met, and the target speed of the corresponding grid surface is determined.

5. The method for determining boundary conditions of an aircraft engine inlet according to claim 3, characterized in that: The determining of the local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds includes: Determine the ratio between the target speed and the critical speed corresponding to each of the grid surfaces by comparison, so as to determine the target Laval number corresponding to each of the grid surfaces; The local static pressure corresponding to each of the grid surfaces is determined based on the target Laval number, the specific heat capacity, and the isentropic relationship.

6. The method for determining boundary conditions of an aircraft engine inlet according to claim 5, characterized in that: The determining of whether the gas flow corresponding to each of the grid surfaces is supersonic, and determining the target pressure value corresponding to each of the grid surfaces based on the corresponding determination result and the local static pressure, includes: determining an average pressure value based on the local static pressure and the area corresponding to each of the grid surfaces; For any of the grid surfaces, determining whether the corresponding target Laval number is greater than a preset threshold to obtain a Laval number determination result; If the Laval number determination result indicates that the gas flow on the current grid surface is greater than the preset threshold, the gas flow on the current grid surface is determined to be supersonic, and the pressure value of the corresponding flow field unit is extrapolated to the current grid surface to determine the corresponding target pressure value; If the Laval number determination result indicates that the Laval number is not greater than the preset threshold, it is determined that the gas flow on the current grid surface is subsonic, and the average pressure value is used as the target pressure value on the current grid surface.

7. The method for determining boundary conditions of an aircraft engine inlet according to claim 1, wherein: The extrapolation based on the center-of-body value of the flow field unit is performed to determine the target density and target velocity component information corresponding to each of the mesh surfaces, so as to determine the target boundary condition corresponding to the engine inlet boundary, including: Obtaining the body center value of the flow field unit corresponding to each of the grid surfaces in the current flow field; For any of the mesh surfaces, the flow field density value in the corresponding body center value and the velocity components in the x, y, and z directions in the spatial coordinate system are extrapolated onto the corresponding current mesh surface to determine the corresponding target density and target velocity component information; The target density, the target velocity component information, and the target pressure value of each of the grid surfaces are used as target boundary conditions corresponding to the engine inlet boundary, so as to complete a corresponding engine inlet boundary condition setting operation based on the target boundary conditions.

8. A device for determining boundary conditions of an aircraft engine inlet, characterized in that: include: a flow acquisition module, configured to collect air flow on each grid surface at the boundary of the engine inlet of the aircraft during a computational fluid dynamics numerical simulation of the aircraft, so as to determine a current actual flow at the engine inlet; a speed determination module, configured to determine a critical specific flow density based on a stagnation point density and a stagnation point sound speed in a current flow field, and determine a target speed corresponding to each of the grid surfaces based on the critical specific flow density, a target flow corresponding to the engine inlet, and a current actual flow; a target pressure value determination module, configured to determine a local static pressure corresponding to each of the grid surfaces based on the critical speed and each of the target speeds, and determine a target pressure value corresponding to each of the grid surfaces based on the corresponding determination result and the local static pressure by judging whether the gas flow corresponding to each of the grid surfaces is supersonic; a boundary condition determination module, configured to perform extrapolation based on the center-of-body values ​​of the flow field units to determine target density and target velocity component information corresponding to each of the mesh surfaces, so as to determine target boundary conditions corresponding to the engine inlet boundary; The target boundary conditions include the target pressure value, the target density, and the target velocity component information of each of the grid surfaces.

9. An electronic device, characterized in that: include: Memory, used to store computer programs; A processor, configured to execute the computer program to implement the method for determining boundary conditions of an aircraft engine inlet according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that Used to store a computer program, which, when executed by a processor, implements the method for determining the boundary conditions of an aircraft engine inlet according to any one of claims 1 to 7.

Images