Method for calculating area of pneumatic throat of special-shaped spray pipe

Abstract

The invention belongs to the technical field of aircraft engine nozzle performance calculation, and particularly relates to a special-shaped nozzle pneumatic throat area calculation method. The method includes the steps that firstly, nozzle jet flow numerical calculation is conducted, and a nozzle jet flow field is obtained; 2, selecting a plurality of pneumatic area calculation sections from the special-shaped spray pipe; 3, extracting flow field parameters of each pneumatic area calculation section from the jet flow field of the jet pipe; 4, calculating the pneumatic area of each pneumatic area calculation section according to the flow field parameters; and 5, calculating the pneumatic area of the section according to each pneumatic area, and determining the pneumatic throat area. According to the method for calculating the pneumatic throat area of the special-shaped nozzle, the pneumatic throat area of the complex special-shaped nozzle can be obtained, and reliable basic data are provided for analysis of the influence of the pneumatic throat area on an engine working line and evaluation of the pneumatic performance of the nozzle.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft engine nozzle performance calculation, and in particular relates to a method for calculating the aerodynamic throat area of ​​a special-shaped nozzle. Background Art

[0002] As an important component of aviation turbojet or turbofan engine, the main function of the nozzle is to discharge the gas and make it continue to expand, convert the available work of the gas into kinetic energy, and eject it backward at high speed, so that the engine generates reaction thrust. The aerodynamic throat area of ​​the nozzle is a key parameter of concern in nozzle design and nozzle performance evaluation. The aerodynamic throat area of ​​the nozzle has the function of controlling the expansion ratio distribution of the airflow in the turbine and the tail nozzle, affecting the common working line of the compressor and the turbine. Improper design of the aerodynamic throat area is likely to worsen the engine-exhaust matching relationship.

[0003] For traditional axisymmetric nozzles, on the one hand, due to the small flow loss in the nozzle, the difference between its geometric throat area and aerodynamic throat area is small; on the other hand, due to the simple geometric features of the nozzle, such as the circular cross-section and axisymmetric geometric features, the position of its aerodynamic throat basically coincides with the position of the geometric throat. However, for complex special-shaped nozzles, there are relatively many difficulties in determining the position and size of the aerodynamic throat. The reason is that the special-shaped nozzle has complex surface changes, may have large spanwise eccentricity, large longitudinal eccentricity, large aspect ratio, multiple S-bends in space, special-shaped outlet shape and other geometric features. These geometric features ensure the radar / infrared stealth performance of the nozzle and are conducive to the integrated design of the fuselage and the nozzle, but at the same time bring many risks of adverse flow phenomena, such as separation, swirl, vortex, secondary flow, etc. These factors cause the aerodynamic throat of the special-shaped nozzle to deviate significantly from the geometric throat, making it difficult to accurately calculate the aerodynamic throat area of ​​the special-shaped nozzle.

[0004] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned defects of the prior art. Summary of the invention

[0005] The purpose of the present application is to provide a method for calculating the aerodynamic throat area of ​​a special-shaped nozzle to solve at least one problem existing in the prior art.

[0006] The technical solution of this application is:

[0007] A method for calculating the aerodynamic throat area of ​​a special-shaped nozzle includes:

[0008] Step 1: perform numerical calculation of the nozzle jet to obtain the nozzle jet flow field;

[0009] Step 2: Select multiple aerodynamic area calculation sections from the special-shaped nozzle;

[0010] Step 3, extracting the flow field parameters of each aerodynamic area calculation section from the nozzle jet flow field;

[0011] Step 4: calculating the aerodynamic area of ​​each aerodynamic area calculation section according to the flow field parameters;

[0012] Step 5: Calculate the aerodynamic area of ​​each cross section according to the aerodynamic area to determine the aerodynamic throat area.

[0013] In at least one embodiment of the present application, in step 1, performing numerical calculation of the nozzle jet to obtain the nozzle jet flow field includes:

[0014] Obtaining a special-shaped nozzle model, and performing nozzle internal flow meshing and nozzle external flow meshing on the special-shaped nozzle model respectively, to obtain a nozzle internal flow calculation domain and a nozzle external flow calculation domain;

[0015] Given the input data, the nozzle jet numerical calculation is performed to obtain the nozzle jet flow field.

[0016] In at least one embodiment of the present application, the nozzle internal flow calculation domain and the nozzle external flow calculation domain use the nozzle outlet cross section as the interface.

[0017] In at least one embodiment of the present application, the input data includes: boundary conditions, time step, flight altitude, Mach number, nozzle inlet total pressure, and nozzle inlet total temperature.

[0018] In at least one embodiment of the present application, when performing numerical calculations of nozzle jets, the finite volume method is used to discretize the NS equations, the inviscid term adopts the Roe format of flux difference splitting, the interpolation template is the third-order MUSCL format, the viscous term adopts the central difference format with second-order accuracy, the time advancement adopts the implicit LU-SGS pseudo-time sub-iteration format, and the turbulence model adopts the two-equation k-ω-SST model.

[0019] In at least one embodiment of the present application, in step 2, the aerodynamic throat position of the special-shaped nozzle is used as a reference, and multiple aerodynamic area calculation sections are selected within a range of 0.2L before and after the reference position, where L is the nozzle length.

[0020] In at least one embodiment of the present application, no less than 8 aerodynamic area calculation sections are selected.

[0021] In at least one embodiment of the present application, the intersection line between the aerodynamic area calculation section and the nozzle wall is a closed curve.

[0022] In at least one embodiment of the present application, the aerodynamic area calculation cross section is parallel to the nozzle inlet cross section.

[0023] In at least one embodiment of the present application, in step three, the flow field parameters of the aerodynamic area calculation section include: flow rate, total pressure, total temperature, and Mach number.

[0024] In at least one embodiment of the present application, a flow-weighted average value of the aerodynamic area calculation cross section is calculated.

[0025] In at least one embodiment of the present application, in step 4, calculating the aerodynamic area of ​​each aerodynamic area calculation section according to the flow field parameters includes:

[0026] The aerodynamic area of ​​each aerodynamic area calculation section is calculated using the isentropic relationship between flow rate and area:

[0027]

[0028] Among them, A i is the aerodynamic area of ​​the i-th aerodynamic area calculation section, R is the gas constant, γ is the specific heat ratio, m i is the flow rate of the i-th aerodynamic area calculation section, P oi is the total pressure of the i-th aerodynamic area calculation section, T oi is the total temperature of the i-th aerodynamic area calculation section, M i is the Mach number of the i-th aerodynamic area calculation section, and N is the number of aerodynamic area calculation sections.

[0029] In at least one embodiment of the present application, in step 5, the minimum aerodynamic area of ​​each aerodynamic area calculation section is used as the aerodynamic throat area:

[0030] A T h=min{A i}(i=1,2,……,N)

[0031] Among them, A Th is the aerodynamic throat area.

[0032] The invention has at least the following beneficial technical effects:

[0033] The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle in the present application can obtain the aerodynamic throat area of ​​a complex special-shaped nozzle, and provide reliable basic data for analyzing the influence of the aerodynamic throat area on the engine working line and evaluating the aerodynamic performance of the nozzle. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a flow chart of a method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to one embodiment of the present application;

[0035] Figure 2 is a schematic diagram of a numerical calculation domain of a nozzle jet flow field according to an embodiment of the present application;

[0036] Figure 3 is a nozzle internal flow calculation domain of one embodiment of the present application;

[0037] Figure 4 It is a schematic diagram of the cross section selection for aerodynamic area calculation according to one embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the embodiment of this application will be described in more detail below in conjunction with the drawings in the embodiment of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of them. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be construed as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.

[0039] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present application.

[0040] The following is combined with Figures 1 to 4 This application is described in further detail.

[0041] The present application provides a method for calculating the aerodynamic throat area of ​​a special-shaped nozzle, including five steps: numerical calculation of nozzle jet, selection of aerodynamic area calculation section, extraction of cross-sectional flow field parameters, calculation of cross-sectional aerodynamic area, and determination of aerodynamic throat area. Figure 1 As shown, specifically:

[0042] Step 1: perform numerical calculation of the nozzle jet to obtain the nozzle jet flow field;

[0043] Step 2: Select multiple aerodynamic area calculation sections from the special-shaped nozzle;

[0044] Step 3, extracting the flow field parameters of each aerodynamic area calculation section from the nozzle jet flow field;

[0045] Step 4: Calculate the aerodynamic area of ​​each aerodynamic area calculation section according to the flow field parameters;

[0046] Step 5. Calculate the aerodynamic area of ​​the cross section based on each aerodynamic area and determine the aerodynamic throat area.

[0047] The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle of the present application firstly, in step 1, performs numerical calculation of the nozzle jet to obtain the nozzle jet flow field, including:

[0048] Obtain the special-shaped nozzle model, and perform nozzle internal flow meshing and nozzle external flow meshing on the special-shaped nozzle model respectively, and obtain the nozzle internal flow calculation domain and the nozzle external flow calculation domain;

[0049] Given the input data, the nozzle jet numerical calculation is performed to obtain the nozzle jet flow field.

[0050] In the preferred embodiment of the present application, for the special-shaped nozzle configuration, the nozzle internal flow grid division and the external flow grid division are performed respectively to obtain independent nozzle internal flow calculation domain and nozzle external flow calculation domain. The two calculation domains use the nozzle outlet section as their flow field parameter information interface. This feature facilitates the subsequent selection of the aerodynamic area calculation section, such as Figure 2 and Figure 3 ; The numerical solution uses the finite volume method to discretize the NS equations, the inviscid term uses the Roe format of flux difference splitting, the interpolation template is the third-order MUSCL format, the viscous term uses the central difference format with second-order accuracy, the time advancement uses the implicit LU-SGS pseudo-time sub-iteration format, and the turbulence model uses the two-equation k-ω-SST model. The data required for the numerical solution include the nozzle numerical model file data, the nozzle working state data, and the nozzle working environment data. Specifically, the nozzle flow field is solved by given parameters such as the boundary conditions, time step, flight altitude, Mach number, nozzle inlet total pressure, and nozzle inlet total temperature.

[0051] The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle of the present application, in step two, when selecting the aerodynamic area calculation section, the position of the aerodynamic throat of the special-shaped nozzle is used as a reference, and multiple aerodynamic area calculation sections are selected within a range of 0.2L before and after the reference position, where L is the nozzle length. No less than 8 aerodynamic area calculation sections are selected, and the intersection line of the aerodynamic area calculation section and the nozzle wall must be a closed curve. There are no special requirements for the orientation of the selected aerodynamic area calculation section, but it is usually most convenient for the aerodynamic area calculation section to be parallel to the nozzle inlet section. The selection of the aerodynamic area calculation section can refer to the method for selecting the position of the calculation section of the special-shaped nozzle, see Figure 4 .

[0052] In the method for calculating the aerodynamic throat area of ​​a special-shaped nozzle of the present application, in step 3, the flow field parameters of the aerodynamic area calculation section include: flow rate, total pressure, total temperature, and Mach number. The flow weighted average value of the aerodynamic area calculation section is calculated and numbered in sequence as 1, 2, ..., N. Based on the numerical solution of the nozzle jet flow field, the specific calculation formula of the required flow field parameters is as follows:

[0053] m i =massFlow()@SP i (i=1,2,……,N)

[0054] P0i=massFlowAve(Total Pressure)@SP i +P Ref (i=1,2,……,N)

[0055] T 0i =massFlowAve(Total Temperature)@SP i (i=1,2,……,N)

[0056] M i =massFlowAve(Mach Number)@SP i (i=1,2,……,N)

[0057] Among them, m i is the flow rate of the i-th aerodynamic area calculation section, P oi is the total pressure of the i-th aerodynamic area calculation section, T oi is the total temperature of the i-th aerodynamic area calculation section, M i is the Mach number of the i-th aerodynamic area calculation section, SP i is the calculation section of the i-th aerodynamic area, P Ref To calculate the reference pressure.

[0058] The method for calculating the aerodynamic throat area of ​​the special-shaped nozzle of the present application, in step 4, calculates the aerodynamic area of ​​each aerodynamic area calculation section according to the flow field parameters, including:

[0059] The aerodynamic area of ​​the calculation section 1 to N is calculated using the isentropic relationship between flow and area:

[0060]

[0061] Among them, A i is the aerodynamic area of ​​the i-th aerodynamic area calculation section, R is the gas constant, γ is the specific heat ratio, m i is the flow rate of the i-th aerodynamic area calculation section, P oi is the total pressure of the i-th aerodynamic area calculation section, Toi is the total temperature of the i-th aerodynamic area calculation section, M i is the Mach number of the i-th aerodynamic area calculation section, and N is the number of aerodynamic area calculation sections.

[0062] In this embodiment, in step 5, the minimum aerodynamic area of ​​each aerodynamic area calculation section is used as the aerodynamic throat area:

[0063] A T h=min{A i}(i=1,2,……,N)

[0064] Among them, A Th is the aerodynamic throat area.

[0065] The calculation method of the aerodynamic throat area of ​​the special-shaped nozzle of the present application ensures the calculation accuracy of the aerodynamic throat area of ​​the nozzle through the high-precision numerical solution of the nozzle jet flow field. The special calculation domain division characteristics of the nozzle internal flow and the external flow ensure the efficiency of the calculation section selection. The calculation of the aerodynamic area of ​​the pipe cross section uses the isentropic relationship between the flow rate of the pipe internal flow and the cross-sectional area to calculate the aerodynamic throat area of ​​the special-shaped nozzle, providing reliable basic data for the analysis of the influence of the aerodynamic throat area on the engine working line and the evaluation of the aerodynamic performance of the nozzle. The present application has the advantages of high precision and high calculation efficiency.

[0066] The above is only a specific implementation 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 a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for calculating the aerodynamic throat area of ​​a special-shaped nozzle, characterized in that: include: Step 1: perform numerical calculation of the nozzle jet to obtain the nozzle jet flow field; Step 2: Select multiple aerodynamic area calculation sections from the special-shaped nozzle; Step 3, extracting the flow field parameters of each aerodynamic area calculation section from the nozzle jet flow field; Step 4: calculating the aerodynamic area of ​​each aerodynamic area calculation section according to the flow field parameters; Step 5: Calculate the aerodynamic area of ​​each cross section according to the aerodynamic area to determine the aerodynamic throat area.

2. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 1, characterized in that: In step 1, the nozzle jet numerical calculation is performed to obtain the nozzle jet flow field, including: Obtaining a special-shaped nozzle model, and performing nozzle internal flow meshing and nozzle external flow meshing on the special-shaped nozzle model respectively, to obtain a nozzle internal flow calculation domain and a nozzle external flow calculation domain; Given the input data, the nozzle jet numerical calculation is performed to obtain the nozzle jet flow field.

3. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 2, characterized in that: The nozzle inner flow calculation domain and the nozzle outer flow calculation domain have the nozzle outlet cross section as the interface.

4. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 3, characterized in that: The input data include: boundary conditions, time step, flight altitude, Mach number, nozzle inlet total pressure, and nozzle inlet total temperature.

5. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 4, characterized in that: When performing numerical calculations of nozzle jets, the finite volume method is used to discretize the NS equations, the inviscid term adopts the Roe format of flux difference splitting, the interpolation template is the third-order MUSCL format, the viscous term adopts the central difference format with second-order accuracy, the time advancement adopts the implicit LU-SGS pseudo-time sub-iteration format, and the turbulence model adopts the two-equation k-ω-SST model.

6. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 1, characterized in that: In step 2, the aerodynamic throat position of the special-shaped nozzle is used as a reference, and multiple aerodynamic area calculation sections are selected within a range of 0.2L before and after the reference position, where L is the nozzle length.

7. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 6, characterized in that: The number of selected aerodynamic area calculation sections shall be no less than 8.

8. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 7, characterized in that: The intersection line between the aerodynamic area calculation section and the nozzle wall is a closed curve.

9. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 8, characterized in that: The aerodynamic area calculation section is parallel to the nozzle inlet section.

10. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 1, characterized in that: In step three, the flow field parameters of the aerodynamic area calculation section include: flow rate, total pressure, total temperature, and Mach number.

11. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 10, characterized in that: Calculate the flow-weighted average of the aerodynamic area calculation section.

12. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 1, characterized in that: In step 4, the aerodynamic area of ​​each aerodynamic area calculation section is calculated according to the flow field parameters, including: The aerodynamic area of ​​each aerodynamic area calculation section is calculated using the isentropic relationship between flow rate and area: Among them, A i is the aerodynamic area of ​​the i-th aerodynamic area calculation section, R is the gas constant, γ is the specific heat ratio, m i is the flow rate of the i-th aerodynamic area calculation section, P oi is the total pressure of the i-th aerodynamic area calculation section, T oi is the total temperature of the i-th aerodynamic area calculation section, M i is the Mach number of the i-th aerodynamic area calculation section, and N is the number of aerodynamic area calculation sections.

13. The method for calculating the aerodynamic throat area of ​​a special-shaped nozzle according to claim 1, characterized in that: In step 5, the minimum aerodynamic area of ​​each aerodynamic area calculation section is used as the aerodynamic throat area: A Th =min{A i }(i=1,2,……,N) Among them, A Th is the aerodynamic throat area.

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