A Method for Environmental Vibration Test of Civil Turboshaft Engine Accessories

Abstract

The present application discloses a method for environmental vibration test of accessories of a civil turboshaft engine, including the steps of: S1. Conduct the maximum imbalance test of the whole engine. During the test, compile the vibration spectrum for the accessory environmental test according to the vibration data in three different directions obtained by three vibration sensors; S2. Conduct the finite element calculation and analysis of the accessory, and correct the connection stiffness of the accessory through the accessory knock frequency test and then substitute it to make the calculated resonance frequency consistent with the knock frequency resonance frequency. Then, initially judge the vibration safety of the accessory through the calculation and analysis results of the finite element vibration response; S3. Conduct the initial accessory environmental vibration test in three vibration directions, and correct the stiffness design of the adapter section according to the maximum imbalance test data; S4. Conduct the final accessory environmental vibration test after completing the stiffness correction of the accessory and the adapter section. The present application comprehensively considers the vibration environment in all directions of the engine, and considering a certain margin, precisely defines the accessory environmental test spectrum, providing technical support for the engine vibration airworthiness compliance.

Description

Technical Field

[0001] This application relates to the technical field of turboshaft engines, and in particular, to a method for environmental vibration testing of civil turboshaft engine accessories. Background Art

[0002] According to the requirements of the airworthiness clause CCAR.63, the design and construction of each type of engine must enable the engine to operate normally throughout its declared flight envelope and the entire operating range of speed and power or thrust, and should not cause excessive stress on any engine components due to vibration, nor should it transmit excessive vibration forces to the aircraft structure.

[0003] Engine accessories belong to the external components of the engine. According to the specific requirements of the Airworthiness Authority Advisory Circular AC33.63, "Vibration tests can be carried out on the engine, or on a vibration table in the laboratory, or both. To determine whether to conduct a full engine test, a laboratory test, or both, at least the vibration environment of the external components should be clear, and whether the laboratory test equipment is suitable for that component and can accurately reflect its vibration environment should be considered."

[0004] For engine accessories, generally, the accessory environmental test is carried out on a vibration table in the laboratory to demonstrate vibration compliance. The determination of the vibration spectrum is the key technology. An overly small vibration spectrum cannot cover the usage requirements of the engine vibration environment, and an overly large vibration spectrum is likely to cause excessive vibration stress on the accessories and lead to failure, resulting in the inability to pass the test.

[0005] The existing method mainly compiles the accessory vibration spectrum based on Chapter 8 "Vibration Test" of "RTCA / DO-160G Environmental Conditions and Test Procedures for Airborne Equipment". According to the compilation method of the "Vibration Test", following the vibration test procedure for airborne equipment on a helicopter, the test frequency and magnitude of sine superposition random are used, and the specified sine frequency is .

[0006] The existing technology has the following technical problems:

[0007] 1) The sine test magnitudes in each direction are fixed, such as 20g for all, without considering the actual vibration level of the engine. The assessment is too severe, resulting in many accessory assessment tests failing to pass.

[0008] 2) The existing technology only requires that "the installation of the equipment under test should make the input vibration motion parallel to one of the three main orthogonal axes of the equipment" according to "RTCA / DO-160G Environmental Conditions and Test Procedures for Airborne Equipment", without considering the installation direction of the equipment under test on the engine.

[0009] 3) The design confirmation of the adapter section has not been carried out, affecting the correctness of the test. Summary of the Invention

[0010] In view of the above technical problems, the present application provides a method for environmental vibration test of accessories of a civil turboshaft engine.

[0011] The present application is implemented through the following solutions:

[0012] A method for environmental vibration test of accessories of a civil turboshaft engine, comprising the steps of:

[0013] S1. Analyze the maximum unbalance of the engine and conduct the maximum unbalance test of the whole engine. During the test, install three vibration sensors for detecting vibrations in the X, Y, and Z directions respectively near the accessories, and compile the vibration spectrum for the accessory environmental test according to the vibration data in three different directions obtained by the three vibration sensors. Among them, when compiling the vibration spectrum for the accessory environmental test, design a single-segment vibration spectrum for the amplitude of the excitation R4 of the power turbine according to a single vibration value, and design a segmented vibration spectrum for the amplitude of the excitation R5 of the gas generator in segments according to different vibration values;

[0014] S2. Conduct finite element calculation and analysis of the accessories. Modify the connection stiffness of the accessories through the accessory knocking frequency test and then substitute it to make the calculated resonance frequency consistent with the knocking frequency resonance frequency, and the error meets the engineering design requirements. Then, preliminarily judge the vibration safety of the accessories through the finite element vibration response calculation and analysis results;

[0015] S3. Design the adapter section and conduct the initial accessory environmental vibration test in three vibration directions. Among them, the three vibration directions during the accessory environmental vibration test are the same as the vibration directions during the maximum unbalance test of the whole engine, and modify the adapter section stiffness design according to the maximum unbalance test data;

[0016] S4. After completing the stiffness modification of the accessories and the adapter section, conduct the final accessory environmental vibration test.

[0017] Further, the X direction is consistent with the engine axis direction, and the Y direction is orthogonal to the X direction and the Z direction.

[0018] Further, in step S1, when designing a single-segment vibration spectrum for the amplitude of the excitation R4 of the power turbine according to a single vibration value, conduct single-segment vibration spectrum design respectively according to the vibration data in three different directions obtained by the three vibration sensors, and the selected single-segment vibration spectrum amplitude meets the following conditions: the vibration spectrum amplitude at each frequency / the test amplitude at each frequency > 1.1.

[0019] Further, in step S1, when designing a segmented vibration spectrum for the amplitude of the excitation R5 of the gas generator in segments according to different vibration values, it specifically includes the steps of:

[0020] Analyze the vibration response of the accessory at different frequencies, and determine in advance the maximum vibration excitation that the accessory can withstand at different frequencies through tests;

[0021] After segmenting the amplitude of the excitation R5 of the gas generator according to the maximum vibration excitation that the accessory can withstand at different frequencies, perform segmented vibration spectrum design according to different vibration magnitudes. Among them, the amplitude of each segmented vibration spectrum satisfies the following conditions: the vibration spectrum amplitude at each frequency / the test amplitude at each frequency > 1.1.

[0022] Furthermore, when performing segmented vibration spectrum design on the amplitude of the excitation R5 of the gas generator according to different vibration magnitudes after segmentation, only perform segmented vibration spectrum design based on the vibration data obtained from the X-direction vibration sensor. Among them, the amplitude of each segmented vibration spectrum satisfies the following conditions: the vibration spectrum amplitude at each frequency / the test amplitude at each frequency > 1.1;

[0023] For the vibration data obtained from the Y-direction vibration sensor and the vibration data obtained from the Z-direction vibration sensor, perform single-segment vibration spectrum design on the amplitude of the excitation R5 of the power turbine according to a single vibration magnitude respectively. The selected single-segment vibration spectrum amplitude satisfies the following conditions: the vibration spectrum amplitude at each frequency / the test amplitude at each frequency > 1.1.

[0024] Furthermore, in step S2, when initially judging the vibration safety of the accessory through the finite element vibration response calculation and analysis results, it specifically includes the steps:

[0025] Establish a finite element model of the accessory, input the vibration spectrum as the excitation condition, and calculate the vibration response of the accessory under random excitation;

[0026] In the calculated vibration response, take the vibration response stress value at a 3σ confidence level, and find the maximum vibration response stress in the entire accessory;

[0027] When the maximum vibration response stress at a 3σ confidence level × 1.2 < the allowable stress value of the material, it is judged that the accessory structure design is safe; otherwise, it is judged that the accessory structure design is unsafe and the accessory structure design needs to be modified.

[0028] Furthermore, establish a finite element model of the accessory through the commercial software ansys.

[0029] Furthermore, in step S3, when modifying the stiffness design of the adapter section according to the maximum unbalance test data, when the error between all the resonance frequencies within the operating speed range in the initial accessory environmental vibration test in each direction of the component and the resonance frequencies in the engine's maximum unbalance test is less than or equal to 5%, the stiffness design of the adapter section is completed.

[0030] Further, all the resonance frequencies are specifically the ones with the largest amplitudes within the operating speed range in the initial accessory environmental vibration test in all directions of the component, and there are no more than four resonance frequencies.

[0031] Further, step S4 specifically includes the following steps:

[0032] Based on the modified adapter section and the accessory, connect the accessory to the vibration table through the adapter section. The excitation direction of the vibration table is the same as the direction in the maximum unbalance test of the whole engine. Carry out the final accessory environmental vibration test according to the specified test procedure.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] 1) In the present application, the vibration values of R4 and R5 are based on the test values of the maximum unbalance test (with a certain margin considered), which is more in line with the actual situation.

[0035] 2) The present application requires the engine placement direction to be the test direction, which is more representative. Only in this way can the test values of the component test correspond to the test values of the whole engine test (maximum unbalance test).

[0036] 3) The present application requires the adapter section design confirmation work to be carried out before the accessory environmental test, so that the installation environment of the accessory can be simulated more accurately.

[0037] 4) The segmented design of the accessory environmental vibration spectrum in the present application is more in line with the actual situation, which is convenient for accurately grasping the excitation magnitude of the engine on the accessory.

[0038] 5) The present application comprehensively considers the vibration environments in all directions of the engine, and with a certain margin considered, precisely defines the accessory environmental test spectrum, providing technical support for the engine vibration airworthiness compliance.

[0039] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The following will refer to the drawings to further elaborate on the present application in detail. Description of the Drawings

[0040] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The schematic embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application:

[0041] Figure 1 is a schematic flow chart of the method for the accessory environmental vibration test of a civil turboshaft engine in a preferred embodiment of the present application;

[0042] Figure 2 is a schematic diagram of the engine installation direction in the present application;

[0043] Figure 3It is a schematic diagram of the vibration test amplitude of the accessory vibration R4 test spectrum and the measured vibration in the X direction;

[0044] Figure 4 It is a schematic diagram of the vibration test amplitude of the accessory vibration R5 test spectrum and the measured vibration in the X direction;

[0045] Figure 5 It is a schematic diagram of the installation position of the accessory on the engine;

[0046] Figure 6 It is a schematic diagram of the installation position of the accessory on the vibration table.

[0047] In the figure: 1. Main mounting node; 2. Aeroengine; 3. Engine axis; 4. Auxiliary mounting node; 5. Accessory; 6. Adapter section; 7. Vibration table. Specific implementation manners

[0048] The following will detail the embodiments of the present application with reference to the accompanying drawings. However, the present application can be implemented in many different ways defined and covered by the following.

[0049] As Figure 1 shown, a preferred embodiment of the present application provides a method for the environmental vibration test of a civil turboshaft engine accessory, including the steps:

[0050] S1. Analyze the maximum unbalance of the engine and conduct the maximum unbalance test of the whole engine. During the test, install three vibration sensors near the accessory to detect the vibration in the X, Y, and Z directions respectively. Compile the vibration spectrum for the accessory environmental test according to the vibration data in three different directions obtained by the three vibration sensors. Among them, when compiling the vibration spectrum for the accessory environmental test, design a single-segment vibration spectrum for the amplitude of the excitation R4 of the power turbine according to a single vibration value, and design a segmented vibration spectrum for the amplitude of the excitation R5 of the gas generator according to different vibration values after segmentation;

[0051] S2. Conduct a finite element calculation and analysis of the accessory. Modify the connection stiffness of the accessory through the accessory frequency knocking test and then substitute it to make the calculated resonance frequency consistent with the frequency knocking resonance frequency, and the error meets the engineering design requirements. Then, preliminarily judge the vibration safety of the accessory through the finite element vibration response calculation and analysis results;

[0052] S3. Design the adapter section and conduct the initial accessory environmental vibration test in three vibration directions. Among them, the three vibration directions during the accessory environmental vibration test are the same as the vibration directions during the maximum unbalance test of the whole engine, and modify the stiffness design of the adapter section according to the maximum unbalance test data;

[0053] S4. After completing the stiffness modification of the accessory and the adapter section, conduct the final accessory environmental vibration test.

[0054] Compared with the prior art, the present embodiment has the following beneficial effects:

[0055] 1) In this embodiment, the vibration values of R4 and R5 are based on the maximum unbalance test value of the entire engine (with a certain margin considered), which is more in line with the actual situation.

[0056] 2) This embodiment requires that the placement direction of the engine be the test direction, which is more representative. Only in this way can the test values of component tests correspond to the test values of the entire engine test (maximum unbalance test).

[0057] 3) This embodiment requires that the design confirmation of the adapter section be carried out before the accessory environmental test, so that the installation environment of the accessory can be simulated more accurately.

[0058] 4) The segmented design of the accessory environmental vibration spectrum in this application is more in line with the actual situation, which is convenient for accurately grasping the excitation magnitude of the engine on the accessory.

[0059] 5) This embodiment comprehensively considers the vibration environments in all directions of the engine, with a certain margin considered, and precisely defines the accessory environmental test spectrum, providing technical support for the airworthiness compliance of engine vibration.

[0060] Specifically, the X direction is consistent with the direction of the engine axis 3, and the Y direction is orthogonal to the X direction and the Z direction. Analyze the maximum unbalance of the aeroengine 2 and conduct the maximum unbalance test of the entire engine. The aeroengine 2 is installed on the test bench through the main mounting node 1 and the auxiliary mounting node 4. Three vibration sensors in different directions are installed near the accessory 5 to obtain vibration data in three different directions. The three vibration sensors must be axial and radial (for example: horizontal, vertical), defined as the X direction, the Y direction, and the Z direction. The Y direction is the horizontal direction and is orthogonal to the X direction and the Z direction. As Figure 2 shown. Then, use the vibration data obtained by the three vibration sensors in the X direction, Y direction, and Z direction to compile the accessory environmental test vibration spectrum.

[0061] The prior art only requires according to the "RTCA / DO-160G Environmental Conditions and Test Procedures for Airborne Equipment" that "the installation of the equipment under test should make the input vibration motion parallel to one of the three main orthogonal axes of the equipment". The installation direction of the equipment under test on the engine is not considered. This embodiment requires that the placement direction of the aeroengine be the test direction, which is more representative. Only in this way can the test values of component tests correspond to the test values of the entire engine test (maximum unbalance test).

[0062] The existing methods mainly compile the vibration spectrum of the annex based on Chapter 8, "Vibration Test", of "RTCA / DO-160G Environmental Conditions and Test Methods for Airborne Equipment". According to the compilation method of the "Vibration Test", following the vibration test procedure for airborne equipment on a helicopter, a test frequency and magnitude of sine superposed on random are adopted. The method for determining the vibration test spectrum frequency is shown in Table 1, and the method for determining the vibration test magnitude is shown in Table 2. The specified sine frequency is within fn from 0.90 to fn within the range of 1.10.

[0063] Table 1 Helicopter Random and Sine Vibration Test Frequencies

[0064]

[0065] Table 2 Helicopter Random and Sine Vibration Test Magnitudes

[0066]

[0067] The prior art refers to the vibration test requirements of "RTCA / DO-160G Environmental Conditions and Test Procedures for Airborne Equipment", and combines the maximum unbalance test of the entire engine to compile the vibration test spectrum of the engine annex (see Table 3). The vibration test spectrum is applicable to the annex installed on the engine body and undergoing environmental tests in accordance with RTCA / DO-160G.

[0068] Table 3 Some Frequencies and Test Magnitudes of the Sine Spectrum of the Engine Durability Vibration Test (Existing Solution)

[0069]

[0070] During the test, following the vibration test procedure for airborne equipment on a helicopter, a test frequency and magnitude of sine superposed on random are adopted. The specified sine frequency is within the range.

[0071] R1 represents the excitation of 1 times the main rotor, R2 represents the excitation of 2 times the main rotor, R3 represents the excitation of the main reduction gear, R4 represents the excitation of the power turbine, and R5 represents the excitation of the gas generator.

[0072] It can be seen that the sine test magnitudes in all directions in the prior art are fixed, such as all being 20g, without considering the actual vibration level of the engine. The assessment is too severe, resulting in many annex assessment tests failing to pass, and it may also be too lenient in assessment, affecting the safety of the engine.

[0073] Therefore, in the preferred embodiment of the present application, in step S1, when designing the single-segment vibration spectrum for the amplitude of the excitation R4 of the power turbine according to a single vibration quantity value, the single-segment vibration spectrum design is respectively performed based on the vibration data in three different directions obtained by three vibration sensors, and the selected single-segment vibration spectrum amplitude satisfies the following condition: the vibration spectrum amplitude at each frequency / the test amplitude at each frequency > 1.1.

[0074] In this embodiment, the vibration spectra of the first-order excitation R1 of the main rotor, the second-order excitation R2 of the main rotor, and the excitation R3 of the main reduction gear are similar to those of the prior art, and the details are shown in Table 4.

[0075] Table 4 Sinusoidal Spectrum Part Frequencies and Test Quantities (R1 - R3) of the Durability Vibration Test of a Certain Engine (This Application)

[0076]

[0077] As Figure 3 As shown in and Table 5, when designing the single-segment vibration spectrum for the amplitude of the excitation R4 of the power turbine according to a single vibration quantity value, the single-segment vibration spectrum design is respectively performed based on the vibration data in three different directions obtained by three vibration sensors, and the selected single-segment vibration spectrum amplitude satisfies the following condition: the vibration spectrum amplitude at each frequency / the test amplitude at each frequency > 1.1. Instead of being fixed at 20g, it is 5g, taking into account the vibration level of the actual engine and avoiding the problem that many accessory assessment tests cannot pass due to overly severe assessment.

[0078] Table 5 Sinusoidal Spectrum Part Frequencies and Test Quantities (R4) of the Durability Vibration Test of a Certain Engine (This Application)

[0079]

[0080] Specifically, in step S1, when performing segmented design of the amplitude of the excitation R5 of the gas generator according to different vibration quantity values after segmentation, it specifically includes the steps:

[0081] S11. Analyze the vibration response of the accessory at different frequencies, and experimentally determine the maximum vibration excitation that the accessory can withstand at different frequencies in advance;

[0082] S12. Perform segmented design of the amplitude of the excitation R5 of the gas generator according to different vibration quantity values after segmentation based on the maximum vibration excitation that the accessory can withstand at different frequencies, where the vibration spectrum amplitude of each segment after segmentation satisfies the following condition: the vibration spectrum amplitude at each frequency / the test amplitude at each frequency > 1.1.

[0083] Table 6 Sinusoidal Spectrum Part Frequencies and Test Quantities (R5) of the Durability Vibration Test of a Certain Engine (This Invention)

[0084]

[0085] Tables 4 - 6 are the environmental vibration test spectra of a certain engine accessory compiled according to the method of the present invention. Compared with the existing solution, the present invention uses the vibration data of the maximum unbalance test to carry out refined design on the vibration magnitudes of R4 and R5. The maximum unbalance test takes into account the most severe vibration state that the engine may endure. Only by using the vibration data of the maximum unbalance test can it be shown that the vibration safety has been fully considered. Considering the actual situation of the accessory test, a single - segment vibration spectrum design is carried out for the amplitude of R4, and a segmented vibration spectrum design is carried out for the amplitude of R5, as Figure 3 、 Figure 4 shown.

[0086] See Figure 4 、Table 6. The logic for the segmented vibration spectrum design of the amplitude of R5 in this application is as follows:

[0087] The natural frequency of a certain accessory is 480 Hz, and the vibration response at 480 Hz in the environmental vibration test is very large, resulting in the accessory failing to pass the environmental test. The preliminary exploratory test found that the accessory can only withstand a vibration excitation of 7 - 8 g at 480 Hz, and exceeding 8 g will cause vibration damage to the accessory and lead to the failure of the test. If a single - segment spectrum of 8 g is used, it cannot meet the condition of "vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.1". If a single - segment vibration spectrum of 10 g is used, the test cannot pass, and it is necessary to modify the accessory structure additionally, resulting in delays in the schedule and unnecessary structural improvements. Therefore, in this embodiment, the above - mentioned problems can be solved through the segmented design of the vibration spectrum. Each segment is designed according to the vibration excitation that can be withstood, instead of a one - size - fits - all approach, thereby reducing the vibration excitation at 480 Hz, while meeting the condition of "vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.1", avoiding unnecessary structural improvement designs, improving the design efficiency, and reducing the design cost.

[0088] Specifically, when carrying out segmented vibration spectrum design on the amplitude of the excitation R5 of the gas generator according to different vibration magnitudes after segmentation, only the vibration data obtained from the X - direction vibration sensor is used for the segmented vibration spectrum design. Among them, the vibration spectrum amplitude of each segment after segmentation satisfies the following condition: vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.1;

[0089] For the vibration data obtained from the Y - direction vibration sensor and the vibration data obtained from the Z - direction vibration sensor, a single - segment vibration spectrum design is carried out on the amplitude of the excitation R5 of the power turbine according to a single vibration magnitude respectively. The selected single - segment vibration spectrum amplitude satisfies the following condition: vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.1.

[0090] Compared with the foregoing embodiments, in this embodiment, when the amplitude of the excitation R5 of the gas generator is segmented and the segmented vibration spectrum is designed according to different vibration magnitudes, the segmented vibration spectrum is designed only based on the vibration data obtained by the vibration sensor in the X direction. The single-segment vibration spectrum design is still used for the Y direction and the Z direction. This is because: according to the results of the preliminary investigation test, the vibration tolerance in the X direction is relatively low, while the vibration tolerances in the Y direction and the Z direction are relatively high. Thus, the vibration spectrum design process can be simplified, the design efficiency can be improved, and the design cost can be reduced.

[0091] Specifically, in step S2, the vibration safety of the accessory is preliminarily judged through the finite element vibration response calculation and analysis results, which specifically includes the following steps:

[0092] S21. Establish a finite element model of the accessory through the commercial software ansys, input the vibration spectrum as the excitation condition, and calculate the vibration response of the accessory under random excitation;

[0093] S22. Take the vibration response stress value at the 3σ confidence level in the calculated vibration response, and find the maximum vibration response stress in the entire accessory;

[0094] S23. When the maximum vibration response stress at the 3σ confidence level × 1.2 < the allowable stress value of the material, it is judged that the accessory structure design is safe; otherwise, it is judged that the accessory structure design is unsafe and the accessory structure design needs to be modified.

[0095] In this embodiment, the vibration safety of the accessory is preliminarily judged through S21 - S23. The benefits include: predicting the vibration tolerance of the accessory and ensuring the success rate of the environmental test.

[0096] Specifically, in step S3, when the stiffness design of the adapter section is corrected according to the maximum unbalance test data, when the error between all the resonance frequencies within the operating speed range in the initial accessory environmental vibration test in each direction of the component and the resonance frequencies in the engine's maximum unbalance test is less than or equal to 5%, the stiffness design of the adapter section is completed.

[0097] In this embodiment, the initial accessory environmental vibration test is carried out in three vibration directions. Among them, the three vibration directions during the accessory environmental vibration test are the same as the vibration directions during the engine's maximum unbalance test. When the stiffness design of the adapter section is corrected according to the maximum unbalance test data, it is judged whether the stiffness design of the adapter section meets the requirements based on whether the error between all the resonance frequencies within the operating speed range in the initial accessory environmental vibration test in each direction of the component and the resonance frequencies in the engine's maximum unbalance test is less than or equal to 5%. The purposes and benefits include: more accurately simulating the actual installation environment of the engine.

[0098] Specifically, all the resonance frequencies are specifically the ones with the largest amplitudes within the operating speed range in the initial accessory environmental vibration test in all directions of the component, and there are no more than four resonance frequencies. The purposes and benefits of such a selection include: being more in line with the requirements of the environmental test (the environmental test requires dwelling at no more than four resonance frequencies).

[0099] Specifically, step S4 specifically includes the steps of:

[0100] Based on the modified adapter section and the accessory, as Figure 5 , Figure 6 shown, connect the accessory to the vibration table through the adapter section. The excitation direction of the vibration table is the same as the direction during the maximum unbalance test of the entire engine. Carry out the final accessory environmental vibration test according to the specified test procedure.

[0101] In this embodiment, when carrying out the final accessory environmental vibration test according to the specified test procedure, connect the accessory to the vibration table through the adapter section, and the excitation direction of the vibration table is the same as the direction during the maximum unbalance test of the entire engine. The purposes and benefits are: ensuring that the vibration excitation direction of the accessory is the same as the actual vibration excitation direction of the engine.

[0102] In summary, compared with the prior art, the civil turboshaft engine accessory environmental vibration test method provided by the above embodiment has the following advantages:

[0103] 1) This application uses the maximum unbalance test measured value (considering a certain margin) as the vibration quantity values of R4 and R5 in Table 1, which is more in line with the actual situation. The fixed value of 20g in the prior art may be too strict in assessment, affecting the passability of the accessory test; or it may be too loose in assessment, affecting the safety of the engine.

[0104] 2) The prior art only requires according to "RTCA / DO-160G Environmental Conditions and Test Procedures for Airborne Equipment" that "the installation of the equipment under test should make the input vibration motion parallel to one of the three main orthogonal axes of the equipment". The installation direction of the equipment under test on the engine is not considered. This application requires using the placement direction of the engine as the test direction, which is more representative. The measured values of the component test can correspond to the measured values of the entire engine test (maximum unbalance test).

[0105] 3) Before the start of the accessory environmental test required by the present invention, it is necessary to carry out the design confirmation work of the transition section. There are no relevant requirements in the prior art. The benefits of carrying out the design confirmation work of the transition section are as follows: more accurately simulate the installation environment of the accessory. The inconsistency of the installation environment may lead to different vibration responses of the "accessory-transition stage system" and the "accessory-engine installation flange system" under the excitation of the same accessory spectrum, thus affecting the effectiveness of the test. The design requirements of the transition section are that the error between the natural frequencies of the "accessory-transition stage system" and the "accessory-engine installation flange system" does not exceed 5%. Only when the natural frequencies are the same can the consistency of the installation environment be ensured.

[0106] Although the preferred embodiments of the present application have been described, those skilled in the art can make additional changes and modifications to these embodiments once they learn the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0107] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A method for environmental vibration test of civil turboshaft engine accessories, characterized in that Including the steps: S1. Analyze the maximum unbalance of the engine and conduct the maximum unbalance test of the whole engine. During the test, install three vibration sensors for detecting vibrations in the X, Y, and Z directions respectively near the accessories, and compile the vibration spectrum for the accessory environmental test based on the vibration data in three different directions obtained by the three vibration sensors. Among them, when compiling the vibration spectrum for the accessory environmental test, design a single-segment vibration spectrum for the amplitude of the excitation R4 of the power turbine according to a single vibration value, and design a segmented vibration spectrum for the amplitude of the excitation R5 of the gas generator according to different vibration values after segmentation; S2. Conduct finite element calculation and analysis of the accessories. Modify the connection stiffness of the accessories through the accessory frequency knocking test and then substitute it to make the calculated resonance frequency consistent with the frequency knocking resonance frequency, and the error meets the engineering design requirements. Then, preliminarily judge the vibration safety of the accessories through the finite element vibration response calculation and analysis results; S3. Design the adapter section and conduct the initial accessory environmental vibration test in three vibration directions. Among them, the three vibration directions during the accessory environmental vibration test are the same as those during the maximum unbalance test of the whole engine, and modify the stiffness design of the adapter section according to the maximum unbalance test data; S4. After completing the stiffness modification of the accessories and the adapter section, conduct the final accessory environmental vibration test.

2. The civil turboshaft engine accessory environmental vibration test method according to claim 1, characterized in that, The X direction is consistent with the engine axis direction, and the Y direction is orthogonal to the X and Z directions.

3. The civil turboshaft engine accessory environmental vibration test method according to claim 1, characterized in that In step S1, when designing a single-segment vibration spectrum for the amplitude of the excitation R4 of the power turbine according to a single vibration value, design a single-segment vibration spectrum respectively based on the vibration data in three different directions obtained by the three vibration sensors. The selected single-segment vibration spectrum amplitude meets the following condition: vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.

1.

4. The civil turboshaft engine accessory environmental vibration test method according to claim 1, characterized in that In step S1, when designing a segmented vibration spectrum for the amplitude of the excitation R5 of the gas generator according to different vibration values after segmentation, it specifically includes the steps: Analyze the vibration response of the accessories at different frequencies and determine in advance the maximum vibration excitation that the accessories can withstand at different frequencies through tests; Design a segmented vibration spectrum for the amplitude of the excitation R5 of the gas generator according to different vibration values after segmentation based on the maximum vibration excitation that the accessories can withstand at different frequencies. Among them, the amplitude of each segment of the vibration spectrum after segmentation meets the following condition: vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.

1.

5. The method for the environmental vibration test of civil turboshaft engine accessories according to claim 1, wherein When designing a segmented vibration spectrum for the amplitude of the excitation R5 of the gas generator according to different vibration values after segmentation, design the segmented vibration spectrum only based on the vibration data obtained by the X-direction vibration sensor. Among them, the amplitude of each segment of the vibration spectrum after segmentation meets the following condition: vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.1; For the vibration data obtained by the Y-direction vibration sensor and the vibration data obtained by the Z-direction vibration sensor, design a single-segment vibration spectrum for the amplitude of the excitation R5 of the power turbine according to a single vibration value respectively. The selected single-segment vibration spectrum amplitude meets the following condition: vibration spectrum amplitude at each frequency / test amplitude at each frequency > 1.

1.

6. The method for the environmental vibration test of civil turboshaft engine accessories according to claim 1, characterized in that In step S2, the vibration safety of the accessory is preliminarily judged by the finite element vibration response calculation and analysis results, which specifically includes the steps: Establish a finite element model of the accessory, input the vibration spectrum as the excitation condition, and calculate the vibration response of the accessory under random excitation; Take the vibration response stress value at 3σ confidence level in the calculated vibration response, and find the maximum vibration response stress in the whole accessory; When the maximum vibration response stress value at 3σ confidence level × 1.2 < the allowable stress value of the material, it is judged that the accessory structure design is safe; otherwise, it is judged that the accessory structure design is unsafe and the accessory structure design needs to be modified.

7. The method for the environmental vibration test of the civil turboprop engine accessory according to claim 6, characterized in that, Establish a finite element model of the accessory through the commercial software ansys.

8. The method for the environmental vibration test of civil turboprop engine accessories according to claim 1, wherein In step S3, when modifying the stiffness design of the transition section according to the maximum unbalance test data, when the error between all the resonance frequencies within the working speed range in the initial accessory environmental vibration test in each direction of the component and the resonance frequencies in the engine maximum unbalance test is less than or equal to 5%, the stiffness design of the transition section is completed.

9. The method for the environmental vibration test of a civil turboshaft engine accessory according to claim 8, wherein All the resonance frequencies are specifically the ones with the largest amplitude within the working speed range in the initial accessory environmental vibration test in each direction of the component, and there are no more than four resonance frequencies.

10. The method for the environmental vibration test of civil turboshaft engine accessories according to claim 1, wherein, Step S4 specifically includes the steps: Based on the modified transition section and accessory, connect the accessory to the vibration table through the transition section. The excitation direction of the vibration table is the same as that in the engine maximum unbalance test, and carry out the final accessory environmental vibration test according to the specified test procedure.

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