A method for layout of aircraft engine accessories based on vibration environment

Abstract

This invention discloses a method for the placement of aero-engine accessories based on vibration environment, belonging to the field of aero-engine structural design technology. The method includes the following main steps: Step 1, establishing a simplified three-dimensional model of the engine load-bearing frame; Step 2, performing mass correction on the engine load-bearing frame; Step 3, determining the radial stiffness variation law of different components of the engine external casing; Step 4, calculating the mode shape data of the engine external casing under each vibration mode; Step 5, obtaining the dataset Ai(x,y,z); Step 6, obtaining the dataset Bi(x,θ); Step 7, defining the maximum vibration displacement as 1, and normalizing the remaining vibration displacements proportionally; Step 8, superimposing the normalized dataset Bi(x,θ,Ci) from Step 7 to obtain the vibration response distribution law of the engine external casing in a two-dimensional plane coordinate system. This method can be used to determine the optimal installation position of engine accessories on the outer surface of the engine casing.

Description

Technical Field

[0001] This invention relates to a method for the location layout of aero-engine accessories based on vibration environment, belonging to the field of aero-engine structural design technology, and is specifically applied to the location layout design of accessories on the outer casing of the engine. Background Technology

[0002] Aircraft engines require numerous external accessories to maintain their normal operation. These accessories typically include fuel controllers, lubricating oil tanks, lubricating oil coolers, igniters, and accumulators. For ease of maintenance, these accessories are usually designed on the outer surface of the engine casing. The engine casing is typically a thin-walled rotating body with low radial stiffness. Accessories mounted on the outer surface of the engine casing bear the vibration load transmitted from the casing's vibration. Installing accessories in locations with less casing vibration is an important means of reducing accessory vibration fatigue failure.

[0003] However, how to determine and arrange the installation positions of accessories on the outer surface of the engine casing based on the radial stiffness and vibration response of various parts of the engine casing is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for the layout of aero-engine accessory positions based on vibration environment.

[0005] This invention is achieved through the following technical solution:

[0006] A method for the layout of aero-engine accessory positions based on vibration environment includes the following main steps:

[0007] Step 1: Create a simplified 3D model of the engine's load-bearing frame and import it into the finite element analysis tool;

[0008] Step 2: Correct the mass of the engine load-bearing frame to make its finite element model mass equal to the actual mass;

[0009] Step 3: Apply uniform pressure to the inner surface of the engine outer casing, calculate the radial deformation of the engine outer casing, and use this to determine the radial stiffness variation law of different components of the engine outer casing.

[0010] Step 4: Calculate the vibration modes of the finite element model of the engine external casing within the frequency range of interest, and obtain the mode shape data of the engine external casing under each vibration mode.

[0011] Step 5: Based on the mode shape data of the engine's external casing under each vibration mode, establish a three-dimensional Cartesian coordinate system to obtain the dataset Ai(x,y,z);

[0012] Step 6: Transform the three-dimensional Cartesian coordinate system from Step 5 into a two-dimensional planar coordinate system to obtain the dataset Bi(x,θ);

[0013] Step 7: Define the maximum vibration displacement as 1, and normalize the remaining vibration displacements proportionally to obtain a dataset Bi(x,θ,Ci) containing the node coordinates and the normalized vibration displacement C.

[0014] Step 8: Superimpose the normalized dataset Bi(x,θ,Ci) from Step 7 to obtain the vibration response distribution law of the engine external casing in the two-dimensional plane coordinate system;

[0015] Step 9: Based on the radial stiffness variation law in Step 3 and the vibration response distribution law in Step 8, select the area on the external casing of the engine where the attachment has small radial deformation and low vibration response.

[0016] The method for mass correction of the engine load-bearing frame in step two includes one or both of the additional mass point method and the density correction method.

[0017] In step three, the uniform pressure applied to the inner surface of the engine's external casing is 0.1 MPa.

[0018] In step three, a radial stiffness variation diagram can be drawn based on the radial stiffness variation law, with the engine axial dimension as the abscissa and the radial deformation as the ordinate.

[0019] The frequency range of interest in step four is 70Hz to 300Hz.

[0020] When establishing the three-dimensional Cartesian coordinate system in step five, the engine's heading is taken as +X, the direction to the right of the heading is taken as +Y, and +Z is determined by the right-hand rule.

[0021] The two-dimensional plane coordinate system in step six is ​​a two-dimensional plane coordinate system that includes the axial dimension and angle of the engine. θ is defined as 0 degrees at the 12 o'clock position directly above the engine in the heading direction, 0 to +180 degrees clockwise in the heading direction, and 0 to -180 degrees counterclockwise.

[0022] In step six If both y and z are positive, then θ = θ + 90°; if both y and z are negative, then θ = -θ; if y is positive and z is negative, then θ = θ; if y is negative and z is positive, then θ = -θ - 90°.

[0023] In step eight, a vibration response distribution diagram can be drawn based on the vibration response distribution law, with the engine axial dimension as the abscissa and the angle θ as the ordinate.

[0024] The i = 1 to 13.

[0025] The beneficial effects of this invention are as follows: It provides a method for calculating the vibration response distribution law of the engine external casing, which can significantly shorten the engine manufacturing cycle and reduce costs. Especially during the engine development stage, this method can determine the optimal installation position of engine accessories on the outer surface of the engine casing. On the other hand, the calculated vibration response distribution law of the engine external casing provides a basis for further verification of sensor measurement point positions in whole-engine testing. Attached Figure Description

[0026] Figure 1 This is a simplified model diagram of the engine casing of the present invention;

[0027] Figure 2 This is a flowchart illustrating the calculation of the vibration response distribution law of the engine external casing according to the present invention;

[0028] Figure 3 This is a schematic diagram illustrating the radial stiffness distribution of the engine's external casing according to the present invention.

[0029] Figure 4 This is a schematic diagram of coordinate system transformation according to the present invention;

[0030] Figure 5 This is a schematic diagram illustrating the vibration response distribution of the engine's external casing according to the present invention. Detailed Implementation

[0031] The technical solution of the present invention is further described below, but the scope of protection is not limited to what is described.

[0032] Example 1:

[0033] like Figures 1 to 5 As shown, the present invention provides a method for the layout of aero-engine accessory positions based on vibration environment, comprising the following main steps:

[0034] Step 1: Create a simplified 3D model of the engine's load-bearing frame and import it into a finite element analysis tool. When using this tool, create a simplified 3D model of the engine's load-bearing frame using common 3D modeling tools such as UG, SolidWorks, and CATIA, and then import it into a common finite element analysis tool (such as ANSYS or ABAQUS) using a common data format (e.g., parasolid, stp).

[0035] Step 2: Correct the mass of the engine load-bearing frame to make its finite element model mass equal to the actual mass. The simplified engine load-bearing frame has a stiffness similar to that of a real engine, but its mass is lower than the actual total mass of the engine. Therefore, it is necessary to correct the mass of the engine load-bearing frame to make the mass of the finite element model the same as the actual mass of the engine.

[0036] Step 3: Apply uniformly distributed pressure to the inner surface of the engine outer casing, calculate the radial deformation of the engine outer casing, and use this to determine the radial stiffness variation of different components of the engine outer casing. The engine outer casing refers to the engine casing where accessories are to be installed. It is not recommended to place external accessories in locations with large radial deformation on the engine outer casing, such as... Figure 3 It is not recommended to place accessories on the outer surface of the two-dimensional nozzle.

[0037] Step 4: Calculate the vibration modes of the finite element model of the engine external casing within the frequency range of interest, and obtain the mode shape data of the engine external casing under each vibration mode.

[0038] Step 5: Based on the mode shape data of the engine's external casing under each vibration mode, establish a three-dimensional Cartesian coordinate system to obtain the dataset Ai(x,y,z).

[0039] Step 6: Transform the three-dimensional Cartesian coordinate system from Step 5 into a two-dimensional planar coordinate system to obtain the dataset Bi(x,θ).

[0040] Step 7: Define the maximum vibration displacement as 1, and normalize the remaining vibration displacements proportionally to obtain a dataset Bi(x,θ,Ci) containing the node coordinates and the normalized vibration displacement C.

[0041] Step 8: Superimpose the normalized dataset Bi(x,θ,Ci) from Step 7 to obtain the vibration response distribution of the engine's external casing in a two-dimensional plane coordinate system. It is not recommended to place external accessories in locations with high vibration response, such as... Figure 5 It is not recommended to place accessories on the outer surface of the fan casing.

[0042] Step 9: Based on the radial stiffness variation law in Step 3 and the vibration response distribution law in Step 8, select the area on the external casing of the engine where the attachment has small radial deformation and low vibration response.

[0043] The method for mass correction of the engine load-bearing frame in step two includes one or both of the additional mass point method and the density correction method.

[0044] In step three, the uniform pressure applied to the inner surface of the engine's external casing is 0.1 MPa.

[0045] In step three, a radial stiffness variation diagram can be drawn based on the radial stiffness variation law, with the engine axial dimension as the abscissa and the radial deformation as the ordinate.

[0046] The frequency range of interest in step four is 70Hz to 300Hz.

[0047] When establishing the three-dimensional Cartesian coordinate system in step five, the engine's heading is taken as +X, the direction to the right of the heading is taken as +Y, and +Z is determined by the right-hand rule.

[0048] The two-dimensional plane coordinate system in step six is ​​a two-dimensional plane coordinate system that includes the axial dimension and angle of the engine. θ is defined as 0 degrees at the 12 o'clock position directly above the engine in the heading direction, 0 to +180 degrees clockwise in the heading direction, and 0 to -180 degrees counterclockwise.

[0049] In step six If both y and z are positive, then θ = θ + 90°; if both y and z are negative, then θ = -θ; if y is positive and z is negative, then θ = θ; if y is negative and z is positive, then θ = -θ - 90°.

[0050] In step eight, a vibration response distribution diagram can be drawn based on the vibration response distribution law, with the engine axial dimension as the abscissa and the angle θ as the ordinate.

[0051] The value of i is 1 to 13. That is, it includes 13 data points. Too few data points will reduce accuracy; too many data points will increase the amount of computation.

[0052] Specifically, such as Figure 3 As shown, the radial deformation of the two-dimensional nozzle section in the engine's external casing is significant; therefore, it is not recommended to place accessories on the outer surface of the two-dimensional nozzle. Figure 5 As shown, the fan casing section of the engine's external casing exhibits a high vibration response, making it unsuitable to place accessories on its outer surface. Therefore, placing accessories on the outer surfaces of the support casing and the outer bypass casing is the optimal design. This application establishes a vibration response analysis method for the entire engine's external casing to reduce vibration of the engine accessory mounting foundation, obtaining the vibration response distribution law of the external casing, and providing a design basis for the installation position of engine accessories.

[0053] The method for the layout of aero-engine accessory positions based on vibration environment provided by this invention has the following advantages:

[0054] This paper presents a method for calculating the vibration response distribution of an engine's external casing, which can significantly shorten the engine manufacturing cycle and reduce costs. Particularly during the engine development stage, this method can determine the optimal installation positions for engine accessories. Furthermore, the calculated vibration response distribution of the engine's external casing provides a basis for determining the locations of sensor measuring points in further engine testing and verification.

[0055] Example 2:

[0056] Based on the vibration environment, this invention designs the accessory locations of aero-engines by utilizing the radial stiffness distribution of the overall load-bearing frame and the vibration response distribution of the external casing. The specific operation steps are as follows:

[0057] 1) The relationship between frequency, stiffness, and mass It is known that the stiffness and mass of the entire engine finite element model must be guaranteed to remain true. Engine stiffness is determined by the load-bearing frame. A certain type of engine is a three-main-load-bearing frame engine, with the load-bearing frames being the fan inlet casing, intermediate casing, and turbine support. Through whole-engine force transmission path analysis, the components included in the entire engine load-bearing frame are determined to be the fan outer casing, intermediate casing, high-pressure compressor casing, combustion chamber casing, turbine outer casing, turbine support, outer bypass casing, and exhaust system. A three-dimensional model of the entire engine, including the aforementioned casings, is established, removing structural features with minimal impact on casing stiffness, such as small holes and bosses. The coordinate system is defined as +X in the engine's heading direction, +Y to the right in the heading direction, and +Z determined by the right-hand rule.

[0058] 2) The mass of the engine 3D model established in step 1) is 194 kg, which is much lower than the actual mass of the engine (1030 kg, of which the rotor mass is 277 kg). Density correction is used to adjust the mass of the 3D model to 753 kg. For example, the actual mass of the intermediate casing is 50.4 kg, the material is TA15, and the density is 4450 kg / m³. The simplified mass of the intermediate casing in the 3D model is only 28.4 kg, and the volume is 6367570 mm³. Therefore, the density of the TA15 material used in the intermediate casing needs to be adjusted from 4450 kg / m³ to 7915 kg / m³.

[0059] 3) Import the engine model established in step 2) using the Workbench general finite element analysis tool. Apply a uniformly distributed pressure of 0.1 MPa to the inner surfaces of the fan casing, outer bypass casing, high-pressure compressor casing, combustion chamber casing, turbine outer casing, and exhaust system to calculate the radial deformation of all casings and obtain the distribution pattern. The calculation results show that the radial stiffness of the exhaust system is low and the casing vibration environment is complex. It is not recommended to place accessories on the exhaust system.

[0060] 4) Using the whole machine finite element model established in step 3), calculate all vibration modes in the range of 70Hz to 300Hz to obtain 13 whole machine vibration modes. Output the mode shape data for all modes on the surface of the engine outer casing;

[0061] 5) Normalize the mode shape data output in step 4). Define the maximum vibration displacement as 1, and normalize the vibration displacements at other positions proportionally to obtain an array Ai(x,y,z,Ci) containing nodal coordinates and normalized vibration displacements (C), where i = 1 to 13. Superimpose the 13th-order normalized vibration mode array.

[0062] 6) Perform coordinate transformation on the modal superposition array A(x,y,z,C) obtained in step 5), converting the three-dimensional Cartesian coordinate system into a two-dimensional planar coordinate system B(x,θ,C) that includes the engine's axial dimensions and angles. The angle θ is calculated using the three-dimensional Cartesian coordinates y and z, and the formula for its value is as follows: If both y and z are positive, θ = θ + 90°; if both y and z are negative, θ = -θ; if y is positive and z is negative, θ = θ; if y is negative and z is positive, θ = -θ - 90°. Angle θ can also be calculated using the Excel formula =ROUND(DEGREES(ATAN2(Z,Y)),1). Steps 5) and 6) are not sequential; coordinate system transformation can be performed first, followed by modal superposition.

[0063] 7) Using the ORIGIN plotting tool, draw a cloud map of the vibration response distribution of the engine's external casing, with the engine axis x as the abscissa and angle θ as the ordinate, based on the array B(x, θ, C) calculated in step 6). The areas with lower vibration response are the intermediate casing and the outer bypass casing cone section; it is recommended to place most accessories in these areas. Accessories are not recommended to be placed on the fan inlet casing, the straight section of the outer bypass casing, or the entire outer surface of the exhaust system.

Claims

1. A method for the layout of aero-engine accessory positions based on vibration environment, characterized in that: The main steps include: Step 1: Create a simplified 3D model of the engine's load-bearing frame and import it into the finite element analysis tool; Step 2: Correct the mass of the engine load-bearing frame to make its finite element model mass equal to the actual mass; Step 3: Apply uniform pressure to the inner surface of the engine outer casing, calculate the radial deformation of the engine outer casing, and use this to determine the radial stiffness variation law of different components of the engine outer casing. Step 4: Calculate the vibration modes of the finite element model of the engine external casing within the frequency range of interest, and obtain the mode shape data of the engine external casing under each vibration mode. Step 5: Based on the mode shape data of the engine's external casing under each vibration mode, establish a three-dimensional Cartesian coordinate system to obtain the dataset Ai(x,y,z); Step 6: Transform the three-dimensional Cartesian coordinate system from Step 5 into a two-dimensional planar coordinate system to obtain the dataset Bi(x,θ); Step 7: Define the maximum vibration displacement as 1, and normalize the remaining vibration displacements proportionally to obtain a dataset Bi(x,θ,Ci) containing the node coordinates and the normalized vibration displacement C. Step 8: Superimpose the normalized dataset Bi(x,θ,Ci) from Step 7 to obtain the vibration response distribution law of the engine external casing in the two-dimensional plane coordinate system; Step 9: Based on the radial stiffness variation law in Step 3 and the vibration response distribution law in Step 8, select the area on the external casing of the engine where the attachment has small radial deformation and low vibration response.

2. The method for the layout of aero-engine accessories based on vibration environment as described in claim 1, characterized in that: The method for mass correction of the engine load-bearing frame in step two includes one or both of the additional mass point method and the density correction method.

3. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: In step three, the uniform pressure applied to the inner surface of the engine's external casing is 0.1 MPa.

4. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: In step three, a radial stiffness variation diagram can be drawn based on the radial stiffness variation law, with the engine axial dimension as the abscissa and the radial deformation as the ordinate.

5. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: The frequency range of interest in step four is 70Hz to 300Hz.

6. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: When establishing the three-dimensional Cartesian coordinate system in step five, the engine's heading is taken as +X, the direction to the right of the heading is taken as +Y, and +Z is determined by the right-hand rule.

7. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: The two-dimensional plane coordinate system in step six is ​​a two-dimensional plane coordinate system that includes the axial dimension and angle of the engine. θ is defined as 0 degrees at the 12 o'clock position directly above the engine in the heading direction, 0 to +180 degrees clockwise in the heading direction, and 0 to -180 degrees counterclockwise.

8. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: In step six If both y and z are positive, then θ = θ + 90°; if both y and z are negative, then θ = -θ; if y is positive and z is negative, then θ = θ; if y is negative and z is positive, then θ = -θ - 90°.

9. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: In step eight, a vibration response distribution diagram can be drawn based on the vibration response distribution law, with the engine axial dimension as the abscissa and the angle θ as the ordinate.

10. The method for the layout of aero-engine accessory positions based on vibration environment as described in claim 1, characterized in that: The i = 1 to 13.

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