A fuel nozzle low cycle fatigue test piece and a design method of the test piece

Abstract

This invention provides a low-cycle fatigue test specimen for fuel nozzles and a design method for the specimen. The fuel nozzle low-cycle fatigue test specimen includes: a load-bearing structure with a through hole and an annular adjustment cavity, wherein the inner shell wall of the load-bearing structure is located between the through hole and the annular adjustment cavity, and the annular adjustment cavity is located between the outer shell wall of the load-bearing structure and the inner shell wall; a first force-applying arm connected to the inner shell wall; and a second force-applying arm connected to the outer shell wall. In summary, the test specimen of this application fully considers the problem of numerous high-stress areas in fuel nozzles. By simulating the structural characteristics of fuel nozzles, it effectively tests the low-cycle fatigue of fuel nozzles during operation, thereby effectively identifying failure sites and ensuring the normal operation of the engine.

Description

Technical Field

[0001] This invention relates to the field of materials testing technology, specifically to a low-cycle fatigue test specimen for a fuel nozzle and a design method for the specimen. Background Technology

[0002] The fuel nozzle of an aero-engine is located in the combustion chamber casing. Its main functions are to deliver and atomize fuel, accelerate the formation of the air-fuel mixture, and ensure stable combustion. During operation, the fuel nozzle is subjected to high temperature and high pressure static loads. Combined with its complex internal structure, these factors lead to localized high-stress areas within the fuel nozzle. Therefore, there is a risk of low-cycle fatigue crack initiation and propagation within the fuel nozzle, ultimately resulting in low-cycle fatigue failure. Considering that fuel nozzles are typically installed inside the combustion chamber casing and have numerous high-stress areas, conducting component-level testing presents technical challenges, including difficulties in testing, identifying failure sites, and quantitative analysis. Summary of the Invention

[0003] The present invention is made to solve the above-mentioned technical problems, and its purpose is to provide a fuel nozzle low-cycle fatigue test specimen and a design method for the specimen, which can facilitate the low-cycle fatigue test of fuel nozzle.

[0004] In a first aspect, this application discloses a fuel nozzle low-cycle fatigue test piece, comprising: a force-bearing structure having a through hole and an annular adjustment cavity, wherein the through hole and the annular adjustment cavity are located between the inner shell wall of the force-bearing structure, and the annular adjustment cavity is located between the outer shell wall of the force-bearing structure and the inner shell wall; a first force-applying arm connected to the inner shell wall; and a second force-applying arm connected to the outer shell wall.

[0005] Optionally, the first force-applying arm is provided with a first cavity communicating with the through hole; and / or, the second force-applying arm is provided with a second cavity communicating with the annular adjustment cavity.

[0006] Optionally, the first cavity has a first cross section parallel to the extension direction of the first force-applying arm, and the second cavity has a second cross section parallel to the extension direction of the second force-applying arm, wherein both the first cross section and the second cross section are triangular.

[0007] Optionally, the test piece is a 3D printed part, and the printing direction of the test piece is from the bottom to the top of the stress-bearing structure. The inner shell wall and the outer shell wall are connected to the top of the stress-bearing structure. The bottom of the stress-bearing structure is provided with a cavity that communicates with the annular adjustment cavity. The side of the first cavity away from the bottom of the stress-bearing structure is a first suspended side, and the side of the second cavity away from the bottom of the stress-bearing structure is a second suspended side. The angle between the first suspended side and the printing direction of the stress-bearing structure, and the angle between the second suspended side and the printing direction of the stress-bearing structure are both less than 45°.

[0008] Optionally, the outer shell wall is provided with a clearance notch, and the first force-applying arm extends outward from the inner shell wall and passes through the clearance notch.

[0009] Optionally, the first force-applying arm is located on the first side of the force-bearing structure, and the second force-applying arm is located on the second side of the force-bearing structure, wherein the first side and the second side are two opposite sides of the force-bearing structure in the radial direction.

[0010] Optionally, the first force-applying arm and the second force-applying arm are arranged flush.

[0011] Optionally, the cross-sections of the first and second lever arms are rectangular.

[0012] Optionally, the junction of the inner shell wall and the first force-applying arm, and / or the junction of the outer shell wall and the second force-applying arm, is provided with a rounded structure.

[0013] Optionally, the first force-applying arm is provided with a first mounting hole, the first mounting hole and the first cavity are arranged opposite to each other along the extension direction of the first force-applying arm and are located on two opposite sides of the first force-applying arm; the second force-applying arm is provided with a second mounting hole, the second mounting hole and the second cavity are arranged opposite to each other along the extension direction of the second force-applying arm and are located on two opposite sides of the second force-applying arm.

[0014] Secondly, this application discloses a design method for a low-cycle fatigue test specimen, the method comprising:

[0015] Based on the static stress analysis results of the fuel nozzle, the static stress concentration structure of the fuel nozzle is obtained;

[0016] Extract the static stress concentration structure of the fuel nozzle to obtain the structural characteristics of the low-cycle fatigue test specimen;

[0017] Local stress analysis was performed on the structural features of the low-cycle fatigue test specimen to determine the stress state of the structural features.

[0018] Based on the stress state of the structural characteristics, add stress application points to the low-cycle fatigue test specimen;

[0019] Static stress analysis is performed on the low-cycle fatigue test specimen. If the stress state of the structural features of the low-cycle fatigue test specimen is consistent with the stress state of the static stress concentration structure of the fuel nozzle, the design of the low-cycle fatigue test specimen is terminated. If they are inconsistent, the stress application points of the low-cycle fatigue test specimen are adjusted and static stress analysis is performed again until the stress state of the structural features of the low-cycle fatigue test specimen is consistent with the stress state of the static stress concentration structure of the fuel nozzle.

[0020] The beneficial effects of this invention are as follows:

[0021] This application discloses a low-cycle fatigue test specimen for a fuel injector, comprising: a force-bearing structure having a through hole and an annular adjustment cavity, wherein the inner shell wall of the force-bearing structure is between the through hole and the annular adjustment cavity, and the annular adjustment cavity is between the outer shell wall of the force-bearing structure and the inner shell wall; a first force-applying arm connected to the inner shell wall; and a second force-applying arm connected to the outer shell wall.

[0022] During the experiment, the first and second force-applying arms are mounted on the testing equipment, which transmits the load to the load-bearing structure, which simulates the S-shaped structural features of the fuel nozzle assembly. Specifically, the load transmitted from the first force-applying arm to the inner shell wall simulates the force on the cold side structure; the load transmitted from the second force-applying arm to the outer shell wall simulates the force on the hot side structure; and the deformation of the annular adjustment cavity caused by the loads on the inner and outer shell walls simulates the deformation caused by the temperature difference between the cold and hot side structures, thereby simulating the stress distribution of the S-shaped structural features of the fuel nozzle assembly under working conditions, achieving the experimental objective.

[0023] In summary, the test specimens in this application fully consider the problem of numerous high-stress areas in the fuel nozzle. By simulating the structural characteristics of the fuel nozzle, the low-cycle fatigue during the operation of the fuel nozzle can be effectively tested, thereby effectively identifying the failure points and ensuring the normal operation of the engine. Attached Figure Description

[0024] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0025] Figure 1 This is a diagram of the fuel injector structure;

[0026] Figure 2 yes Figure 1 Enlarged view of point I;

[0027] Figure 3 This is a structural diagram of the test specimen of the present invention;

[0028] Figure 4 This is a diagram of the internal structure of the test piece of this invention;

[0029] Figure 5 This is a stress analysis diagram of the test piece without a cavity in this invention;

[0030] Figure 6 yes Figure 5 A magnified view of a portion of the image;

[0031] Figure 7 This is a stress analysis diagram of the test piece with the cavity provided in this invention;

[0032] Figure 8 yes Figure 7 A magnified view of a portion of the image.

[0033] Explanation of reference numerals in the attached figures:

[0034] 100 - Load-bearing structure, 101 - Through hole, 102 - Annular adjustment cavity, 110 - Inner shell wall, 120 - Outer shell wall, 121 - Clearance notch

[0035] 200 - First lever arm, 210 - First cavity, 211 - First suspended side, 201 - First mounting hole

[0036] 300 - Second lever arm, 310 - Second cavity, 311 - Second suspended side, 301 - Second mounting hole

[0037] 20-Fuel nozzle assembly, 21-Nozzle housing, 22-Injector rod core, 23-Fuel collector ring housing, 24-Interstage section, 221-S-shaped structural feature, 222-Cold side structure, 223-Hot side structure.

[0038] 10 - Combustion outdoor unit casing. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0040] First, combine Figure 1 and Figure 2 Introduction to the structure of fuel nozzles:

[0041] like Figure 1As shown, the fuel nozzle assembly 20 is installed in the outer casing 10 of the combustion chamber. The fuel nozzle assembly 20 consists of a nozzle housing 21, an injection rod core 22, a fuel collector ring housing 23, and an interstage section 24, among other structures. These components are connected as a single unit by high-temperature brazing. The fuel nozzle assembly 20 is located inside the combustion chamber, where the nozzle housing 21 has a relatively high temperature, while the internal fuel passages of the injection rod core 22 are relatively cooler due to fuel cooling. The injection rod core 22 incorporates multiple flexible structures to absorb the deformation caused by the temperature difference between the inside and outside. Figure 2 A typical S-shaped structural feature 221 inside the fuel injector core 22 is shown. This S-shaped structural feature 221 is designed as a flexible structure to absorb the deformation difference between the cold side structure 222 and the hot side structure 223 of the fuel injector core caused by temperature differences.

[0042] To avoid the risk of low-cycle fatigue crack initiation and propagation within the fuel nozzle assembly 20, leading to low-cycle fatigue failure, a low-cycle fatigue test is necessary. However, fuel nozzles are typically installed inside the combustion chamber casing, which contains numerous high-stress areas. Conducting component-level testing presents technical challenges, including difficulty in testing, identifying failure sites, and quantitative analysis. Therefore, to address these challenges, this application designs a test piece simulating the S-shaped structural feature 221 of the fuel nozzle assembly 20. The following section discusses... Figure 3 and Figure 8 This application describes the test specimens of this application:

[0043] This application discloses a low-cycle fatigue test specimen for a fuel nozzle. The test specimen can be a 3D printed part and includes a force-bearing structure 100, a first force-applying arm 200, and a second force-applying arm 300.

[0044] The load-bearing structure 100 is provided with a through hole 101 and an annular adjustment cavity 102. The through hole 101 is oriented along the axial direction of the load-bearing structure 100, which is also the printing direction X of the test piece. The inner shell wall 110 of the load-bearing structure 100 is located between the through hole 101 and the annular adjustment cavity 102. The annular adjustment cavity 102 is located between the outer shell wall 120 of the load-bearing structure 100 and the inner shell wall 110. The structural features formed by the outer shell wall 120, the inner shell wall 110, and the annular adjustment cavity 102 are used to simulate the S-shaped structural feature 221 of the fuel nozzle assembly 20. The first force-applying arm 200 is connected to the inner shell wall 110; the second force-applying arm 300 is connected to the outer shell wall 120.

[0045] During the test, the first force-applying arm 200 and the second force-applying arm 300 are mounted on the test equipment, and the test equipment transmits the load to the load-bearing structure 100, which simulates the S-shaped structural feature 221 of the fuel nozzle assembly 20. Specifically, the load transmitted by the first force-applying arm 200 to the inner shell wall 110 is used to simulate the force on the cold side structure 222; the load transmitted by the second force-applying arm 300 to the outer shell wall 120 is used to simulate the force on the hot side structure 223; the deformation of the annular adjustment cavity 102 caused by the load on the inner shell wall 110 and the outer shell wall 120 is used to simulate the deformation caused by the temperature difference between the cold side structure 222 and the hot side structure 223, thereby simulating the stress distribution of the S-shaped structural feature 221 of the fuel nozzle assembly 20 under working conditions, and achieving the test objective.

[0046] In summary, the test specimens in this application fully consider the problem of numerous high-stress areas in the fuel nozzle. By simulating the structural characteristics of the fuel nozzle, the low-cycle fatigue during the operation of the fuel nozzle can be effectively tested, thereby effectively identifying the failure points and ensuring the normal operation of the engine.

[0047] Optionally, the first force-applying arm 200 is provided with a first cavity 210 communicating with the through hole 101, and the second force-applying arm 300 is provided with a second cavity 310 communicating with the annular adjustment cavity 102. In this way, on the first aspect, the provision of the first cavity 210 and the second cavity 310 can save printing material and printing time, and can make the test piece lighter and easier to clamp; on the other hand, test pieces without the first cavity 210 and the second cavity 310, such as... Figure 5 and Figure 6 As shown, the test piece with the first cavity 210 and the second cavity 310 is as follows: Figure 7 and Figure 8 As shown, Figures 5-8 It can be seen that whether the first cavity 210 and the second cavity 310 are provided or not does not affect the stress distribution at the intersection of the inner shell wall 110, the outer shell wall 120 and the clearance notch 121, thus ensuring the accuracy of the test.

[0048] Optionally, the first cavity 210 has a first cross section parallel to the extension direction of the first force-applying arm 200, and the second cavity 310 has a second cross section parallel to the extension direction of the second force-applying arm 300. Both the first and second cross sections are triangular, and triangles are simple geometric shapes that are relatively easy to form using additive manufacturing processes.

[0049] Optionally, as described above, the test piece is a 3D printed part, and the printing direction X of the test piece extends from the bottom to the top of the load-bearing structure 100. The inner shell wall 110 and the outer shell wall 120 are connected at the top of the load-bearing structure 100, and the bottom of the load-bearing structure 100 is provided with a cavity opening that connects to the annular adjustment cavity 102. The side of the first cavity 210 away from the bottom of the load-bearing structure 100 is the first suspended side 211, and the side of the second cavity 310 away from the bottom of the load-bearing structure 100 is the second suspended side 311. The angle between the first suspended side 211 and the printing direction X of the load-bearing structure 100, and the angle between the second suspended side 311 and the printing direction X of the load-bearing structure 100 are both less than 45°, which facilitates printing and ensures printing feasibility.

[0050] Optionally, the outer shell wall 120 is provided with a clearance notch 121, and the first force arm 200 extends outward from the inner shell wall 110 and passes through the clearance notch 121, which can improve the compactness of the structure.

[0051] Optionally, the first force-applying arm 200 is located on the first side of the force-bearing structure 100, and the second force-applying arm 300 is located on the second side of the force-bearing structure 100. The first side and the second side are two opposite sides of the force-bearing structure 100 in the radial direction Y. This facilitates the installation of the test piece and allows the loads applied to the inner shell wall 110 and the outer shell wall 120 to be transmitted from the two opposite sides respectively. The transmission path can ensure the accuracy of the test results.

[0052] Optionally, the first force-applying arm 200 and the second force-applying arm 300 are flush. Here, "flush" means that the two end faces of the first force-applying arm 200 along its thickness direction are coplanar with the two end faces of the second force-applying arm 300 along its thickness direction; the two side faces of the first force-applying arm 200 along its width direction are coplanar with the two side faces of the second force-applying arm 300 along its width direction (where the width direction is the printing direction X); one side face of the first force-applying arm 200 and one side face of the second force-applying arm 300 are coplanar with the bottom surface of the test piece; and the lengths of the first force-applying arm 200 and the second force-applying arm 300 are the same. This facilitates the control of the matching degree between the load transmitted from the first force-applying arm 200 to the inner shell wall 110 and the load transmitted from the second force-applying arm 300 to the outer shell wall 120.

[0053] Optionally, the cross-section of the first lever arm 200 and the second lever arm 300 is rectangular, and the cross-section is perpendicular to the thickness direction. Such a rectangular plate structure is easy to install.

[0054] Optionally, a rounded structure is provided at the junction of the inner shell wall 110 and the first force-applying arm 200, and / or at the junction of the outer shell wall 120 and the second force-applying arm 300. The rounded structure can prevent cracks from appearing at the connection position due to stress concentration, thereby ensuring the effective conduct of the test and the service life of the test piece.

[0055] Optionally, the first lever arm 200 is provided with a first mounting hole 201, and the second lever arm 300 is provided with a second mounting hole 301. Both the first mounting hole 201 and the second mounting hole 301 are used to insert pins and to transfer loads using pins.

[0056] Optionally, the first mounting hole 201 and the first cavity 210 are arranged opposite to each other along the extension direction of the first force-applying arm 200 and are located on two opposite sides of the first force-applying arm 200; the extension direction is the direction of load transmission on the first force-applying arm 200, the first mounting hole 201 is the initial position of load transmission, and setting the first cavity 210 away from the first mounting hole 201 can further reduce the influence of the first cavity 210 on load transmission and ensure the accuracy of the test.

[0057] Similarly, the second mounting hole 301 and the second cavity 310 are arranged opposite each other along the extension direction of the second force-applying arm 300 and are located on two opposite sides of the second force-applying arm 300. The extension direction is the direction of load transmission on the second force-applying arm 300, and the second mounting hole 301 is the initial position for load transmission. Setting the second cavity 310 away from the second mounting hole 301 can further reduce the influence of the second cavity 310 on load transmission and ensure the accuracy of the test.

[0058] This application also discloses a design method for a low-cycle fatigue test specimen, used for the aforementioned test specimen, the method comprising:

[0059] Based on the static stress analysis results of the fuel nozzle, the static stress concentration structure of the fuel nozzle is obtained. The static stress concentration structure is... Figure 2 The S-shaped structural feature 221;

[0060] Extract the static stress concentration structure of the fuel nozzle to obtain the structural features of the low-cycle fatigue test piece, namely the structural features formed by the annular adjustment cavity 102, the inner shell wall 110, and the outer shell wall 120 in the stress-bearing structure 100.

[0061] Local stress analysis is performed on the structural features of low-cycle fatigue test specimens to determine the stress state of the structural features; the stress state includes any one or more of elastic stress, elastic strain, plastic stress, plastic strain, and stress-strain distribution;

[0062] Based on the stress state of the structural characteristics, the stress application points of the low-cycle fatigue test specimen are added; the stress application points are the first stress arm 200 and the second stress arm 300.

[0063] Static stress analysis is performed on the low-cycle fatigue test specimen. If the stress state of the structural features of the low-cycle fatigue test specimen is consistent with the stress state of the static stress concentration structure of the fuel nozzle, the design of the low-cycle fatigue test specimen is terminated. If they are inconsistent, the stress application points of the low-cycle fatigue test specimen are adjusted and static stress analysis is performed again until the stress state of the structural features of the low-cycle fatigue test specimen is consistent with the stress state of the static stress concentration structure of the fuel nozzle.

[0064] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A fuel nozzle low-cycle fatigue test specimen, characterized in that, include: A load-bearing structure (100) is provided with a through hole (101) and an annular adjustment cavity (102). The space between the through hole (101) and the annular adjustment cavity (102) is the inner shell wall (110) of the load-bearing structure (100), and the space between the outer shell wall (120) and the inner shell wall (110) is the annular adjustment cavity (102). The first force-applying arm (200) is connected to the inner shell wall (110); The second force arm (300) is connected to the outer casing wall (120).

2. The low-cycle fatigue test specimen according to claim 1, characterized in that, The first force-applying arm (200) is provided with a first cavity (210) communicating with the through hole (101); And / or, The second force-applying arm (300) is provided with a second cavity (310) that communicates with the annular adjustment cavity (102).

3. The low-cycle fatigue test specimen according to claim 2, characterized in that, The first cavity (210) has a first cross section parallel to the extension direction of the first force-applying arm (200), and the second cavity (310) has a second cross section parallel to the extension direction of the second force-applying arm (300). Both the first cross section and the second cross section are triangular.

4. The low-cycle fatigue test specimen according to claim 3, characterized in that, The test piece is a 3D printed part, and the printing direction (X) of the test piece is from the bottom to the top of the stress-bearing structure (100). The inner shell wall (110) and the outer shell wall (120) are connected at the top of the stress-bearing structure (100). The bottom of the stress-bearing structure (100) is provided with a cavity opening that communicates with the annular adjustment cavity (102). The side of the first cavity (210) away from the bottom of the force-bearing structure (100) is the first suspended side (211), and the side of the second cavity (310) away from the bottom of the force-bearing structure (100) is the second suspended side (311). The angle between the first suspended side (211) and the printing direction (X) of the force-bearing structure (100) and the angle between the second suspended side (311) and the printing direction (X) of the force-bearing structure (100) are both less than 45°.

5. The low-cycle fatigue test specimen according to claim 1, characterized in that, The outer shell wall (120) is provided with a clearance notch (121), and the first force arm (200) extends outward from the inner shell wall (110) and passes through the clearance notch (121).

6. The low-cycle fatigue test specimen according to claim 5, characterized in that, The first force-applying arm (200) is located on the first side of the force-receiving structure (100), and the second force-applying arm (300) is located on the second side of the force-receiving structure (100). The first side and the second side are two opposite sides of the radial (Y) direction of the force-receiving structure (100).

7. The low-cycle fatigue test specimen according to claim 6, characterized in that, The first force-applying arm (200) and the second force-applying arm (300) are arranged flush with each other.

8. The low-cycle fatigue test specimen according to claim 1, characterized in that, The junction of the inner shell wall (110) and the first force-applying arm (200), and / or the junction of the outer shell wall (120) and the second force-applying arm (300) are provided with a rounded structure.

9. The low-cycle fatigue test specimen according to claim 2, characterized in that, The first force-applying arm (200) is provided with a first mounting hole (201). The first mounting hole (201) and the first cavity (210) are arranged opposite to each other along the extension direction of the first force-applying arm (200) and are located on two opposite sides of the first force-applying arm (200). The second force-applying arm (300) is provided with a second mounting hole (301). The second mounting hole (301) and the second cavity (310) are arranged opposite to each other along the extension direction of the second force-applying arm (300) and are located on two opposite sides of the second force-applying arm (300).

10. A method for designing a low-cycle fatigue test specimen, used for the low-cycle fatigue test specimen of any one of claims 1 to 9, characterized in that, The method includes: Based on the static stress analysis results of the fuel nozzle, the static stress concentration structure of the fuel nozzle is obtained; Extract the static stress concentration structure of the fuel nozzle to obtain the structural characteristics of the low-cycle fatigue test specimen; Local stress analysis was performed on the structural features of the low-cycle fatigue test specimen to determine the stress state of the structural features. Based on the stress state of the structural characteristics, add stress application points to the low-cycle fatigue test specimen; Static stress analysis is performed on the low-cycle fatigue test specimen. If the stress state of the structural features of the low-cycle fatigue test specimen is consistent with the stress state of the static stress concentration structure of the fuel nozzle, the design of the low-cycle fatigue test specimen is terminated. If they are inconsistent, the stress application points of the low-cycle fatigue test specimen are adjusted and static stress analysis is performed again until the stress state of the structural features of the low-cycle fatigue test specimen is consistent with the stress state of the static stress concentration structure of the fuel nozzle.

Images