Method for determining thrust coefficient of double-duct spray pipe of aero-engine

Abstract

The invention belongs to the technical field of aero-engine double-duct nozzle thrust coefficient determination, and particularly relates to an aero-engine double-duct nozzle thrust coefficient determination method which comprises the following steps: step 1, constructing a double-duct nozzle calculation model; 2, setting an air inlet condition and outlet back pressure of the double-duct spray pipe, and calculating to obtain flow field distribution and inlet and outlet parameters of the double-duct spray pipe according to a calculation model of the double-duct spray pipe; 3, based on the inlet and outlet parameters of the double-duct spray pipe, the theoretical thrust of the inner duct spray pipe and the theoretical thrust of the outer duct spray pipe are obtained through calculation; step 4, based on the theoretical thrust of the inner duct spray pipe, the theoretical thrust of the outer duct spray pipe and the real thrust of the double-duct spray pipe; 5, on the basis of the inlet and outlet parameters of the double-duct spray pipe, the one-dimensional isentropic complete expansion thrust of the double-duct spray pipe is calculated; and 6, calculating the thrust coefficient of the double-duct nozzle based on the real thrust and the one-dimensional isentropic complete expansion thrust of the double-duct nozzle.

Description

Technical Field

[0001] This application belongs to the technical field of determining the thrust coefficient of a dual-duct nozzle for aero-engines, and specifically relates to a method for determining the thrust coefficient of a dual-duct nozzle for aero-engines. Background Technology

[0002] Aero engines, especially those with variable thermocycle capabilities, often have multiple geometric adjustment variables, such as compression components like guide vanes, stator vanes, turbine guide vanes, and nozzles. Compared to conventional cycle turbofan aero engines, variable thermocycle aero engines have more than one main exhaust nozzle. As the number of bypass ducts increases, they often have multiple exhaust nozzles. Currently, the most common type is the dual bypass nozzle, which consists of an inner bypass nozzle and an outer bypass nozzle.

[0003] In aero-engines with dual bypass nozzles, the inner bypass nozzle typically has an axisymmetric convergent-divergent configuration, while the outer bypass nozzle has a convergent configuration, such as... Figure 2 As shown, the definition of the section designation is as follows:

[0004] 7-Inner channel nozzle inlet section;

[0005] 8-Internal duct nozzle throat section;

[0006] 9-Internal duct nozzle exit section;

[0007] 37 - External bypass nozzle inlet section;

[0008] 39 - External bypass nozzle outlet section;

[0009] β-Inner duct nozzle expansion section expansion angle.

[0010] The nozzle thrust coefficient is defined as the ratio of the actual total thrust of the nozzle to the total thrust under one-dimensional isentropic full expansion. In aero-engine performance calculations, the demand for the nozzle thrust coefficient is significant, and accurate calculation of the nozzle thrust coefficient is crucial for the overall performance calculation and prediction of aero-engines.

[0011] Currently, no research on the calculation of thrust coefficient of dual-duct nozzles for aero-engines has been found in publicly available technical documents. There are only methods for calculating the thrust coefficient of a single nozzle of conventional turbofan engines. These methods mainly involve simulating the flow field of a single nozzle to calculate the flow field, obtain the theoretical thrust and isentropic expansion thrust, and then calculate the thrust coefficient of the nozzle.

[0012] Since the total thrust generated by the dual-duct nozzle of an aero-engine is not equal to the arithmetic sum of the thrust generated by the two single nozzles, and is often less than the arithmetic sum of the thrust generated by the dual-duct nozzle alone, and since the nozzle design is relatively novel and there are complex interferences between the flow fields, the conventional method for calculating the thrust coefficient of a single nozzle of a turbofan engine is not well applicable to the calculation of the thrust coefficient of a dual-duct nozzle.

[0013] This application is made in view of the aforementioned technical deficiencies. Summary of the Invention

[0014] The purpose of this application is to provide a method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, so as to quickly and accurately determine the thrust coefficient of the dual-duct nozzle.

[0015] The technical solution of this application is:

[0016] A method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, comprising:

[0017] Step 1: Construct a calculation model for a dual-duct nozzle;

[0018] Step 2: Set the inlet conditions and outlet back pressure of the dual-duct nozzle, and use the dual-duct nozzle calculation model to calculate the flow field distribution and inlet and outlet parameters of the dual-duct nozzle.

[0019] Step 3: Based on the inlet and outlet parameters of the dual-duct nozzle, calculate the theoretical thrust of the inner duct nozzle and the theoretical thrust of the outer duct nozzle.

[0020] Step 4: Theoretical thrust of inner-duct nozzle, theoretical thrust of outer-duct nozzle, and actual thrust of dual-duct nozzle;

[0021] Step 5: Based on the inlet and outlet parameters of the dual-duct nozzle, calculate the one-dimensional isentropic fully expanded thrust of the dual-duct nozzle;

[0022] Step 6: Calculate the thrust coefficient of the dual-duct nozzle based on the actual thrust and the one-dimensional isentropic fully expanded thrust.

[0023] According to at least one embodiment of this application, in the above-described method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, in step one, the parameters required for constructing the dual-duct nozzle calculation model include the throat area A8 of the inner duct nozzle, the exit area A9 of the inner duct nozzle, the spread angle β of the inner duct nozzle, and the throat area A39 of the outer duct nozzle, which are obtained by measurement.

[0024] A two-dimensional planar model of the dual-duct nozzle was constructed, and the far-field boundary was determined.

[0025] For the dual-duct nozzle calculation model, CFD calculation software was used to divide the model mesh, set boundary conditions, select a turbulence model, and set the calculation residuals.

[0026] According to at least one embodiment of this application, in the above-described method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, step two involves setting the dual-duct nozzle inlet conditions, including the total temperature at the inlet of the inner duct nozzle. Total pressure ,flow Total temperature at the inlet of the bypass nozzle Total pressure ,flow ;

[0027] Setting the outlet back pressure of the dual-duct nozzle This is due to environmental pressures;

[0028] Given the inlet conditions and outlet back pressure of the dual-duct nozzle, and a given number of iterations, the calculation is started using the dual-duct nozzle calculation model. After the calculation converges, the flow field distribution of the dual-duct nozzle is obtained, and the parameter distribution of the flow field of the dual-duct nozzle, as well as the inlet and outlet parameters, including temperature, pressure, and flow rate parameters, can be viewed.

[0029] According to at least one embodiment of this application, in the above-described method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, step four specifically comprises:

[0030] ;

[0031] in,

[0032] This represents the actual thrust of a dual-duct nozzle.

[0033] The thrust loss coefficient for a dual-duct nozzle;

[0034] The theoretical thrust of the internal duct nozzle;

[0035] This represents the theoretical thrust of the bypass nozzle.

[0036] According to at least one embodiment of this application, in the above-described method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, step four involves determining the thrust loss coefficient of the dual-duct nozzle. Specifically:

[0037] On the test bench, aero-engine tests are conducted to record the performance of the aero-engine under different conditions, including the total thrust of the dual-bypass nozzle under different intake conditions and exit back pressure. Calculate the thrust loss coefficient of a dual-duct nozzle. :

[0038] ;

[0039] Statistical analysis of thrust loss coefficients of dual-duct nozzles under different inlet conditions and outlet back pressures The thrust loss coefficient is obtained. Pressure ratio with dual-duct nozzle Change relationship curve ,in, .

[0040] Based on the set inlet conditions and outlet back pressure of the dual-duct nozzle, the pressure drop ratio of the dual-duct nozzle was calculated. Therefore, based on the thrust loss coefficient Pressure ratio with dual-duct nozzle Change relationship curve The thrust loss coefficient of the dual-duct nozzle was obtained. .

[0041] According to at least one embodiment of this application, in the above-described method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, step five specifically comprises:

[0042] ;

[0043] ;

[0044] ;

[0045] ;

[0046] ;

[0047] in,

[0048] The velocity of the fully expanded airflow in the inner duct nozzle;

[0049] The velocity of the fully expanded airflow in the outer bypass nozzle;

[0050] The total pressure at the nozzle outlet of the inner duct;

[0051] This refers to the total pressure at the outlet of the outer bypass nozzle.

[0052] The airflow adiabatic index;

[0053] It is the gas constant;

[0054] The thrust of the one-dimensional isentropic fully expanded nozzle within the confined space;

[0055] The thrust of the one-dimensional isentropic fully expanded outer bypass nozzle;

[0056] The outlet flow rate of the inner duct nozzle;

[0057] This refers to the outlet flow rate of the outer bypass nozzle.

[0058] It is the one-dimensional isentropic fully expanded thrust of a dual-duct nozzle.

[0059] According to at least one embodiment of this application, in the above-described method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, step six specifically comprises:

[0060] . Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the dual-duct nozzle configuration of an aero-engine provided in an embodiment of this application;

[0062] Figure 2 This is a schematic diagram of the method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine provided in an embodiment of this application.

[0063] To better illustrate this embodiment, some content in the accompanying drawings may be omitted, enlarged, or reduced. They are for illustrative purposes only and should not be construed as limiting the scope of this application. Detailed Implementation

[0064] To make the technical solution and advantages of this application clearer, the technical solution of this application will be described in a clearer and more complete manner below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only some embodiments of this application, and are only used to explain this application, not to limit this application. It should be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, and other related parts can be referred to the general design.

[0065] Furthermore, unless otherwise defined, the technical or scientific terms used in this application description shall have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The word "comprising" as used in this application description indicates that the concept preceding the word encompasses the concepts listed following the word and their equivalents, without excluding other related concepts.

[0066] A method for determining the thrust coefficient of a dual-duct nozzle in an aero-engine, such as Figure 1As shown, the thrust loss coefficient caused by flow field interference in the inner and outer double-duct nozzles was calculated by means of numerical simulation and experimental measurement. This solves the problem of deviation between the calculated thrust coefficient and the true value caused by flow field interference in the double-duct nozzles, which can improve the calculation accuracy of the true thrust of aero-engines and increase the accuracy of the thrust coefficient calculation results.

[0067] Step 1: Construct a calculation model for a dual-duct nozzle.

[0068] The parameters required to construct the calculation model of the dual-duct nozzle include the throat area A8 of the inner duct nozzle, the exit area A9 of the inner duct nozzle, the spread angle β of the inner duct nozzle, and the throat area A39 of the outer duct nozzle, which can be obtained through measurement.

[0069] Since the dual-duct nozzle of an aero-engine is an axisymmetric structure, a two-dimensional planar model can be established, and the far-field boundary can be determined.

[0070] The setup and preparation work before the calculation is completed by using CFD calculation software to divide the model mesh, set boundary conditions, select the turbulence model, and set the calculation residuals.

[0071] Step 2: Set the inlet conditions and outlet back pressure of the dual-duct nozzle, and use the dual-duct nozzle calculation model to calculate the flow field distribution and inlet / outlet parameters of the dual-duct nozzle.

[0072] Dual-duct nozzle inlet conditions include the total temperature at the inlet of the inner duct nozzle. Total pressure ,flow Total temperature at the inlet of the bypass nozzle Total pressure ,flow .

[0073] Exit back pressure of a dual-duct nozzle This refers to environmental pressure.

[0074] Under the given inlet conditions and outlet back pressure of the dual-duct nozzle, and with a specified number of iterations, the calculation begins using the dual-duct nozzle calculation model. Once the calculation converges, the flow field distribution of the dual-duct nozzle is obtained. The parameter distribution of the flow field of the dual-duct nozzle, as well as inlet and outlet parameters such as temperature, pressure, and flow rate, can be viewed.

[0075] Step 3: Based on the inlet and outlet parameters of the dual-duct nozzle, calculate the theoretical thrust of the inner duct nozzle and the theoretical thrust of the outer duct nozzle.

[0076] Step 4: Theoretical thrust of the inner bypass nozzle, theoretical thrust of the outer bypass nozzle, and actual thrust of the dual bypass nozzle.

[0077] ;

[0078] in,

[0079] This represents the actual thrust of a dual-duct nozzle.

[0080] The thrust loss coefficient for a dual-duct nozzle;

[0081] The theoretical thrust of the internal duct nozzle;

[0082] This represents the theoretical thrust of the bypass nozzle.

[0083] Dual-duct nozzle thrust loss coefficient This reflects the degree of thrust loss caused by flow field interference. The larger the value, the smaller the thrust loss. It can be determined using the following method:

[0084] On the test bench, aero-engine tests are conducted to record the performance of the aero-engine under different conditions, including the total thrust of the dual-bypass nozzle under different intake conditions and exit back pressure. The thrust is generated jointly by the inner duct nozzle and the outer bypass nozzle. Considering the losses caused by flow field interference, the sum of the theoretical thrust of the inner duct nozzle and the theoretical thrust of the outer bypass nozzle is... This does not equal the total thrust of a dual-duct nozzle. Calculate the thrust loss coefficient of a dual-duct nozzle. :

[0085] .

[0086] Statistical analysis of thrust loss coefficients of dual-duct nozzles under different inlet conditions and outlet back pressures The thrust loss coefficient is obtained. Pressure ratio with dual-duct nozzle Change relationship curve ,in, .

[0087] Based on the set inlet conditions and outlet back pressure of the dual-duct nozzle, the pressure drop ratio of the dual-duct nozzle was calculated. Therefore, based on the thrust loss coefficient Pressure ratio with dual-duct nozzle Change relationship curve The thrust loss coefficient of the dual-duct nozzle was obtained. .

[0088] Step 5: Based on the inlet and outlet parameters of the dual-duct nozzle, calculate the one-dimensional isentropic fully expanded thrust of the dual-duct nozzle.

[0089] Based on the inlet and outlet parameters of the dual-duct nozzle, the one-dimensional ideal fully expanded airflow velocity of the inner duct nozzle and the outer duct nozzle can be calculated, and then the one-dimensional ideal isentropic fully expanded thrust of the inner duct nozzle and the outer duct nozzle can be calculated. The sum of these values ​​gives the one-dimensional ideal isentropic fully expanded thrust of the dual-duct nozzle. In the calculation of the ideal thrust, it is assumed that there is no interference between the inner duct nozzle and the outer duct nozzle.

[0090] ;

[0091] ;

[0092] ;

[0093] ;

[0094] ;

[0095] in,

[0096] The velocity of the fully expanded airflow in the inner duct nozzle;

[0097] The velocity of the fully expanded airflow in the outer bypass nozzle;

[0098] The total pressure at the nozzle outlet of the inner duct;

[0099] This refers to the total pressure at the outlet of the outer bypass nozzle.

[0100] This is the airflow adiabatic index, which is usually taken as 1.4;

[0101] This is the gas constant, which is typically taken as 8.314 J / (mol·K);

[0102] The thrust of the one-dimensional isentropic fully expanded nozzle within the confined space;

[0103] The thrust of the one-dimensional isentropic fully expanded outer bypass nozzle;

[0104] The outlet flow rate of the inner duct nozzle;

[0105] This refers to the outlet flow rate of the outer bypass nozzle.

[0106] It is the one-dimensional isentropic fully expanded thrust of a dual-duct nozzle.

[0107] Step 6: Calculate the thrust coefficient of the dual-duct nozzle based on the actual thrust and the one-dimensional isentropic fully expanded thrust.

[0108] .

[0109] The method for determining the thrust coefficient of a dual-duct nozzle for aero-engines disclosed in the above embodiments considers the influence of the dual-duct nozzle structure on the nozzle flow field and thrust. It uses numerical simulation and experimental measurement to calculate the theoretical total thrust generated by the inner and outer dual-duct nozzles, and obtains the thrust loss coefficient of the dual-duct nozzle with the help of thrust test results. Considering the thrust loss caused by flow field interference, the theoretical thrust is corrected for loss. Based on the basic principles of aero-engines, the one-dimensional isentropic fully expanded thrust of the inner and outer dual-duct nozzles is calculated separately. According to the thrust coefficient calculation principle, the thrust coefficient of the dual-duct nozzle is calculated, which fills the gap in the determination of the thrust coefficient of dual-duct nozzles, solves the problem of thrust coefficient calculation deviation caused by flow field interference of dual-duct nozzles, and increases the accuracy of the thrust coefficient calculation results.

[0110] The technical solution of this application has been described in conjunction with the preferred embodiments shown in the accompanying drawings. Those skilled in the art should understand that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine, characterized in that, include: Step 1: Construct a calculation model for a dual-duct nozzle; Step 2: Set the inlet conditions and outlet back pressure of the dual-duct nozzle, and use the dual-duct nozzle calculation model to calculate the flow field distribution and inlet and outlet parameters of the dual-duct nozzle. Step 3: Based on the inlet and outlet parameters of the dual-duct nozzle, calculate the theoretical thrust of the inner duct nozzle and the theoretical thrust of the outer duct nozzle. Step 4: Theoretical thrust of inner-duct nozzle, theoretical thrust of outer-duct nozzle, and actual thrust of dual-duct nozzle; Step 5: Based on the inlet and outlet parameters of the dual-duct nozzle, calculate the one-dimensional isentropic fully expanded thrust of the dual-duct nozzle; Step 6: Calculate the thrust coefficient of the dual-duct nozzle based on the actual thrust and one-dimensional isentropic fully expanded thrust of the dual-duct nozzle.

2. The method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine according to claim 1, characterized in that, In step one, the parameters required to construct the dual-duct nozzle calculation model include the throat area A8 of the inner duct nozzle, the exit area A9 of the inner duct nozzle, the spread angle β of the inner duct nozzle, and the throat area A39 of the outer duct nozzle, which are obtained through measurement. A two-dimensional planar model of the dual-duct nozzle was constructed, and the far-field boundary was determined. For the dual-duct nozzle calculation model, CFD calculation software was used to divide the model mesh, set boundary conditions, select a turbulence model, and set the calculation residuals.

3. The method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine according to claim 2, characterized in that, In step two, the intake conditions for the dual-duct nozzle are set, including the total temperature at the inlet of the inner duct nozzle. Total pressure ,flow Total temperature at the inlet of the bypass nozzle Total pressure ,flow ; Setting the outlet back pressure of the dual-duct nozzle This is due to environmental pressures; Given the inlet conditions and outlet back pressure of the dual-duct nozzle, and a given number of iterations, the calculation is started using the dual-duct nozzle calculation model. After the calculation converges, the flow field distribution of the dual-duct nozzle is obtained, and the parameter distribution of the flow field of the dual-duct nozzle, as well as the inlet and outlet parameters, including temperature, pressure, and flow rate parameters, can be viewed.

4. The method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine according to claim 3, characterized in that, Step four, specifically: ； in, This represents the actual thrust of a dual-duct nozzle. The thrust loss coefficient for a dual-duct nozzle; The theoretical thrust of the internal duct nozzle; This represents the theoretical thrust of the bypass nozzle.

5. The method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine according to claim 4, characterized in that, In step four, the thrust loss coefficient of the dual-duct nozzle is determined. Specifically: On the test bench, aero-engine tests are conducted to record the performance of the aero-engine under different conditions, including the total thrust of the dual-bypass nozzle under different intake conditions and exit back pressure. Calculate the thrust loss coefficient of the dual-duct nozzle. : ； Statistical analysis of thrust loss coefficients of dual-duct nozzles under different inlet conditions and outlet back pressures The thrust loss coefficient is obtained. Pressure ratio with dual-duct nozzle Change relationship curve ,in, ; Based on the set inlet conditions and outlet back pressure of the dual-duct nozzle, the pressure drop ratio of the dual-duct nozzle was calculated. Therefore, based on the thrust loss coefficient Pressure ratio with dual-duct nozzle Change relationship curve The thrust loss coefficient of the dual-duct nozzle was obtained. .

6. The method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine according to claim 5, characterized in that, Step five, specifically: ； ； ； ； ； in, The velocity of the fully expanded airflow in the inner duct nozzle; The velocity of the fully expanded airflow in the outer bypass nozzle; The total pressure at the nozzle outlet of the inner duct; This refers to the total pressure at the outlet of the outer bypass nozzle. The airflow adiabatic index; It is the gas constant; The thrust of the one-dimensional isentropic fully expanded nozzle within the confined space; The thrust of the one-dimensional isentropic fully expanded outer bypass nozzle; The outlet flow rate of the inner duct nozzle; This refers to the outlet flow rate of the outer bypass nozzle. It is the one-dimensional isentropic fully expanded thrust of a dual-duct nozzle.

7. The method for determining the thrust coefficient of a dual-duct nozzle for an aero-engine according to claim 6, characterized in that, Step six, specifically: 。

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