A method for calculating the aerodynamic throat area of a profiled nozzle

Abstract

The application belongs to the technical field of aircraft engine nozzle performance calculation, and particularly relates to a special-shaped nozzle aerodynamic throat area calculation method. The method comprises the following steps: step one, performing nozzle jet numerical calculation to obtain a nozzle jet flow field; step two, selecting a plurality of aerodynamic area calculation sections from the special-shaped nozzle; step three, extracting flow field parameters of each aerodynamic area calculation section from the nozzle jet flow field; step four, calculating the aerodynamic area of each aerodynamic area calculation section according to the flow field parameters; and step five, determining the aerodynamic throat area according to the aerodynamic area of each aerodynamic area calculation section. The special-shaped nozzle aerodynamic throat area calculation method can obtain the aerodynamic throat area of a complex special-shaped nozzle, and provides reliable basic data for the influence analysis of the aerodynamic throat area on the engine working line and the evaluation of the nozzle aerodynamic performance.

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] The nozzle, a crucial component of an aviation turbojet or turbofan engine, primarily discharges and expands the gases, converting their available work into kinetic energy before ejecting them backward at high speed, generating thrust. The nozzle's aerodynamic throat area is a key parameter of interest in nozzle design and performance evaluation. This area controls the distribution of the airflow expansion ratio between the turbine and tailpipe, affecting the common operating line of the compressor and turbine. Improper aerodynamic throat area design can significantly degrade engine-to-exhaust matching.

[0003] For traditional axisymmetric nozzles, on the one hand, the difference between the geometric throat area and the aerodynamic throat area is small due to the low internal flow losses. On the other hand, due to the simple geometric features of the nozzle, such as the circular cross-section and axisymmetric geometry, the aerodynamic throat position generally coincides with the geometric throat position. However, for complex, irregular nozzles, determining the aerodynamic throat position and size presents relatively more difficulties. This is because irregular nozzles have complex surface variations and may have large spanwise and longitudinal eccentricities, large aspect ratios, multiple spatial S-bends, and irregular outlet shapes. These geometric features ensure the nozzle's radar / infrared stealth performance and facilitate the integrated design of the airframe and nozzle, but they also bring the risk of numerous adverse flow phenomena, such as separation, swirl, vortex, and secondary flow. These factors cause the aerodynamic throat of irregular nozzles to deviate significantly from the geometric throat, making accurate calculation of the aerodynamic throat area of ​​irregular nozzles more difficult.

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

[0005] The purpose of this 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 based on 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 to obtain a nozzle internal flow calculation domain and a nozzle external flow calculation domain;

[0015] Given 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 calculation section of the i-th aerodynamic area, 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 five, 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 this application can obtain the aerodynamic throat area of ​​a complex special-shaped nozzle, providing reliable basic data for analyzing the impact 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 This 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 Schematic diagram of the numerical calculation domain of the nozzle jet flow field according to one embodiment of the present application;

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

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

[0038] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments 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 the embodiments. 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 understood 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 this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this 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. Therefore, it should not be understood as limiting the scope of protection of this application.

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

[0041] This 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: extract 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 first performs a numerical calculation of the nozzle jet in step 1 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 to obtain the nozzle internal flow calculation domain and nozzle external flow calculation domain;

[0049] Given 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 separately to obtain independent nozzle internal flow calculation domain and nozzle external flow calculation domain. The two calculation domains use the nozzle outlet cross section as the interface of their flow field parameter information. This feature facilitates the subsequent selection of the aerodynamic area calculation cross section, such as Figure 2 and Figure 3 The numerical solution uses the finite volume method to discretize the NS equations. The inviscid terms use the Roe scheme with flux difference splitting, the interpolation template uses the third-order MUSCL scheme, the viscous terms use the central difference scheme with second-order accuracy, the time marching uses the implicit LU-SGS pseudo-time sub-iteration scheme, and the turbulence model uses the two-equation k-ω-SST model. The numerical solution requires data including the nozzle numerical model file data, nozzle operating status data, and nozzle operating environment data. Specifically, the nozzle flow field is solved by given parameters such as the numerical solution 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 2, 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 selection method of 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 shaped nozzle disclosed herein, 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 of the aerodynamic area calculation sections is calculated and sequentially numbered 1, 2, ..., N. Based on the numerical solution of the nozzle jet flow field, the specific calculation formula for 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 calculation section of the i-th aerodynamic area, M i is the Mach number of the calculation section of the i-th aerodynamic area, SP i is the calculation section of the i-th aerodynamic area, P Ref For calculating the reference pressure.

[0058] The method for calculating the aerodynamic throat area of ​​a 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 calculation section of the i-th aerodynamic area, 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 proposed method for calculating the aerodynamic throat area of ​​a profiled nozzle ensures accurate calculation of the nozzle's aerodynamic throat area through a high-precision numerical solution of the nozzle's jet flow field. Its unique computational domain partitioning for internal and external nozzle flows ensures efficient cross-section selection. The calculation of the aerodynamic area of ​​a pipe cross section utilizes the isentropic relationship between internal flow and cross-sectional area to calculate the aerodynamic throat area of ​​the profiled nozzle. This provides reliable basic data for analyzing the impact of the aerodynamic throat area on the engine operating line and evaluating nozzle aerodynamic performance. This application offers advantages such as high accuracy and computational efficiency.

[0066] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection 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 based on 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 to obtain a nozzle internal flow calculation domain and a nozzle external flow calculation domain; Given 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 internal flow calculation domain and the nozzle external 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 with 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 aerodynamic area calculation sections selected 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 value 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 calculation section of the i-th aerodynamic area, 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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