A method for verifying the airworthiness compliance of an aviation turbofan engine swallowing a bird

Abstract

The present application provides a method for verifying the airworthiness compliance of an aviation turbofan engine for swallowing a bird. The method determines the type of test required according to different engines, and then conducts bird-swallowing airworthiness compliance verification in different ways for birds of different weights. When conducting any single test, only targeted tests need to be carried out, and there is no need for the coordinated cooperation of multiple engine resources, test bench resources, debugging and test projection bird resources, human resources, etc. The method is comprehensive and systematic, ensuring that the verification is reasonable and effective, while shortening the working cycle, saving test resources, and reducing development costs. The entire method has been successfully applied in the airworthiness compliance verification of the turbofan engine's bird-swallowing capability.

Description

Technical Field

[0001] The present application belongs to the field of aviation engine bird swallowing test, and in particular relates to a method for verifying the airworthiness compliance of aviation turbofan engines swallowing birds. Background Art

[0002] With the rapid development of aviation, the impact of birds on flight safety has become increasingly prominent. Verification of bird swallowing capability has become a crucial component of civil turbofan engine development. Regarding bird swallowing capability verification, the bird swallowing clauses of the airworthiness regulations specify the safety impacts and operational requirements for engines under bird swallowing conditions of different weight classes. While whole-machine testing provides a relatively direct and accurate assessment of an engine's bird swallowing capability based on test results, completing all of these verifications through whole-machine testing requires excessive resources and a lengthy timeframe, given the airworthiness regulations' requirements for single large birds, medium birds, additional medium birds, small birds, and large birds with multiple feathers. This makes it difficult to implement in practical aeroengine engineering applications. Therefore, it is crucial to design a bird swallowing capability verification method that accurately verifies compliance with airworthiness regulations while meeting the resource and time constraints of actual aeroengine development. Summary of the Invention

[0003] The purpose of this application is to provide a method for verifying the airworthiness compliance of an aviation turbofan engine for swallowing a bird, so as to solve the problem in the prior art that the bird swallowing test requires a lot of resources and a long period of time.

[0004] The technical solution of this application is: a method for verifying the airworthiness compliance of an aviation turbofan engine swallowing a bird, comprising:

[0005] Obtain engine data and determine the type of test to be conducted, including improved / derivative engine verification tests and newly developed engine verification tests. The newly developed engine verification tests include single large bird verification tests, medium bird verification tests, small bird verification tests, and multi-feather large bird verification tests;

[0006] To determine whether to conduct an improved / derivative engine verification test, first determine whether the corresponding prototype engine before the improvement / derivation has passed the bird swallowing airworthiness compliance verification; if so, conduct a comparative analysis between the improved / derivative engine and the prototype engine; if not, conduct the bird swallowing capability airworthiness compliance verification according to the newly developed engine verification test;

[0007] Determine whether to conduct verification tests on newly developed engines and determine the specific test types;

[0008] If it is determined that a single large bird verification test is to be conducted, then 1) the test parameter requirements shall be determined in accordance with the airworthiness regulations and a single large bird whole aircraft test verification shall be conducted; or 2) the verification shall be conducted using an equivalent method of containment test;

[0009] If it is determined that a mid-bird verification test is to be conducted, 1) the test parameter requirements shall be determined in accordance with the airworthiness regulations and a mid-bird whole-machine test verification shall be conducted; 2) additional integrity assessment verification shall be conducted;

[0010] If it is decided to conduct a small bird test verification, first determine whether it has passed the mid-bird swallowing capability verification. If so, the mid-bird verification result is equivalent to verifying the small bird capability; if not, determine the test parameter requirements according to the airworthiness regulations and conduct a small bird full-machine test verification;

[0011] If it is determined that a multi-feather large bird verification test is to be conducted, then 1) a multi-feather large bird whole machine test verification is to be conducted in accordance with the test parameter requirements; or 2) a bird strike component string installation whole machine verification is to be conducted.

[0012] Preferably, in the improved / derivative engine verification test, after conducting a comparative analysis between the improved / derivative engine and the prototype engine, it is again determined whether the relevant design features are the same as or better than those of the prototype engine. If not, the bird-swallowing capability airworthiness compliance verification is carried out in accordance with the engine verification test; if so, the user is consulted whether he agrees to be exempted from the test. If so, the test is waived.

[0013] Preferably, the contents of the comparative analysis between the improved / derivative engine and the prototype engine include: changes in fan blade configuration; changes in the tangential speed of the fan blade tip; changes in the swing ability of the fan blade root in the mortise and tenon; changes in the axial distance between the fan blade and the boost stage inlet guide vane; changes in the inclination angle of the leading edge of the boost stage inlet guide vane; changes in the form of the conical surface of the fan cap; changes in the shape of the flow path of the boost stage outlet neck; changes in the VBV bleed valve; changes in the fan casing containment ring; changes in the core engine design; and changes in the materials of fan-related components.

[0014] Preferably, the inclusion test equivalence verification method includes:

[0015] Determine test parameters in accordance with airworthiness regulations, conduct bird strike tests on fan components, and measure the axial load caused by bird strikes during component tests;

[0016] Regarding the influence of axial load, based on the axial load measurement results in the bird strike component test, the analysis proves that it does not exceed the bearing load capacity. If successful, the axial load influence analysis is completed;

[0017] To determine the effects of blade containment and rotor imbalance, the weight of fallen / broken blades from the bird strike component test, blade containment, and rotor imbalance tests was compared to determine the differences in their impact on casing containment. Based on the weight, center of gravity, and test speed of the fallen / broken blades, the centrifugal loads on the debris under the two test conditions were calculated and compared to determine the differences in the impact of the unbalanced loads.

[0018] To address the impact of mounting section loads, dynamic simulation analysis based on the finite element model of the entire aircraft and mounting section safety strength tests were conducted to compare and analyze the differences in mounting section loads under bird strike / blade loss conditions.

[0019] To address the impact of surge loads, consider fan blade damage and the impact of bird bodies on airflow channel obstruction, and compare and analyze surge energy under conditions of large bird strikes or blade loss.

[0020] To address the impact of torque load, consider rotor seizure under bird strike / blade loss conditions. Based on parameters such as rotor speed, rotor moment of inertia, and time, compare and analyze the maximum torque under the two conditions. Alternatively, analyze and verify whether the torque load under the bird strike condition is within the engine's tolerable range.

[0021] In terms of fire prevention, methods such as fragment trajectory and energy analysis under bird strike / blade loss conditions can be used to compare and analyze the differences in fuel tank damage and fuel pipe rupture under the two conditions;

[0022] Conduct a comprehensive comparative analysis of the load effects under the above two test conditions to prove that the bird strike load is less severe than the blade containment and rotor imbalance tests. If successful, the comprehensive comparative analysis will be completed;

[0023] Based on the results of the verification of the containment capability, it is indirectly verified whether the engine's ability to swallow a single large bird meets the airworthiness requirements.

[0024] Preferably, the multi-feather large bird whole machine test verification method includes:

[0025] Determine the test parameters in accordance with the requirements for large birds with multiple feathers as specified in the airworthiness regulations, and verify the bird swallowing capability in the form of a complete aircraft test;

[0026] The test is carried out in conjunction with the single large bird test. The bird's weight, speed and impact position are tested and verified in accordance with airworthiness regulations. The test procedures and passing standards after swallowing the bird are also tested and verified in accordance with airworthiness regulations.

[0027] Preferably, the bird strike component serial installation whole machine verification method includes:

[0028] Determine test parameters in accordance with airworthiness regulations and conduct bird strike tests on fan components. The test pieces shall at least include components that have a critical impact on the swallowing ability of large, feathered birds.

[0029] Conduct impact analysis on overall machine dynamics and performance direction;

[0030] The fan component that has completed the bird strike test is installed in series on the engine, and the whole engine is operated to verify whether it meets the airworthiness requirements.

[0031] The present application provides a method for verifying the airworthiness of an aviation turbofan engine swallowing a bird. The method determines the type of test required according to different engines, and then conducts bird-swallowing airworthiness verification in different ways for birds of different weights. When conducting any single test, only targeted tests need to be carried out, and there is no need for the coordinated cooperation of multiple engine resources, test bench resources, debugging and test projection bird resources, human resources, etc. The method is comprehensive and systematic, ensuring that the verification is reasonable and effective, while shortening the working cycle, saving test resources, and reducing development costs. The entire method has been successfully applied in the airworthiness verification of the turbofan engine's bird-swallowing capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions provided by this application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of this application.

[0033] Figure 1 This is a schematic diagram of the rectification process for this application. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0035] A method for verifying the airworthiness compliance of an aviation turbofan engine swallowing a bird, such as Figure 1 As shown, the following steps are included:

[0036] Step S100: Acquire engine data and determine the type of test to be performed, that is, determine whether the engine type is an improved / derivative engine or a newly developed engine. Different engines are subjected to different tests, including improved / derivative engine verification tests and newly developed engine verification tests. Newly developed engine verification tests include single large bird verification tests, medium bird verification tests, small bird verification tests, and multi-feather large bird verification tests.

[0037] Step S200: Determine whether to conduct an improved / derivative engine verification test. First, determine whether the prototype engine corresponding to the engine before improvement / derivation has passed the bird swallowing airworthiness compliance verification. If so, conduct a comparative analysis between the improved / derivative engine and the prototype engine. If not, conduct a bird swallowing capability airworthiness compliance verification according to the newly developed engine verification test.

[0038] During the verification test of the improved / derivative engine, a comparative analysis between the improved / derivative engine and the prototype engine shall be conducted. Preferably, the comparative analysis between the improved / derivative engine and the prototype engine shall include:

[0039] 1) Changes in fan blade configuration, such as whether the fan blade has a vibration-damping shoulder, fan blade geometry, fan blade chord length, fan blade thickness, fan blade material, etc.;

[0040] 2) Changes in fan blade tip tangential speed;

[0041] 3) Changes in the fan blade root's ability to deflect in the groove;

[0042] 4) Change in the axial distance between the fan blades and the boost stage inlet guide vanes;

[0043] 5) Change in the inclination angle of the leading edge of the boost stage inlet guide vane;

[0044] 6) Changes in the cone shape of the fan cap;

[0045] 7) Changes in the shape of the flow path at the outlet neck of the booster stage;

[0046] 8) Changes in VBV bleed valve;

[0047] 9) Changes in the fan casing containment ring, such as: containment ring structure, containment ring material, containment ring thickness, etc.;

[0048] 10) Core engine design changes;

[0049] 11) Changes in materials of fans and other related components;

[0050] 12) Analyze other design changes related to bird-swallowing capability based on the specific actual situation of the improvement.

[0051] After the above analysis is completed, it is determined again whether the relevant design features are the same, similar or better than the prototype engine. If not, the bird swallowing capability airworthiness compliance verification is carried out according to the engine verification test; if so, the user is consulted whether he agrees to be exempted from the test. If so, the test is waived.

[0052] Step S300: determining whether to conduct a new engine verification test and determining the specific test type;

[0053] If a single large bird verification test is conducted, there are two verification methods, including:

[0054] 1) Determine the test parameter requirements in accordance with airworthiness regulations and conduct bird swallowing capability verification of a single large bird whole-aircraft test;

[0055] 2) Conduct equivalence verification of containment testing;

[0056] According to different engine models, one of the appropriate verification methods is selected. When conducting inclusive test equivalent verification, the resources required for the test are greatly reduced, the development cost is significantly reduced, the verification cycle is significantly shortened, and the development efficiency is significantly improved.

[0057] The verification steps are as follows:

[0058] ① Determine the test parameters in accordance with airworthiness regulations, conduct bird strike tests on fan components, and measure the axial load caused by the bird strike during the component test;

[0059] ② Regarding the influence of axial load, based on the axial load measurement results in the bird strike component test, analyze and prove that it does not exceed the bearing load capacity. If successful, the axial load influence analysis is completed;

[0060] ③ Regarding the effects of blade containment and rotor imbalance, the weight of the fallen / broken blades from the bird strike component test, blade containment, and rotor imbalance tests was compared to determine the differences in the blade's impact on casing containment. Based on the weight, center of gravity, and test speed of the fallen / broken blades, the centrifugal loads on the debris under the two test conditions were calculated and compared to determine the differences in the impact of the unbalanced loads.

[0061] ④ To address the impact of mounting section loads, dynamic simulation analysis based on the finite element model of the entire aircraft and mounting section safety strength tests were conducted to compare and analyze the differences in mounting section loads under bird strike / blade loss conditions.

[0062] ⑤ In view of the impact of surge loads, considering fan blade damage and the impact of bird bodies on the airflow channel, a comparative analysis of surge energy under conditions of large bird strikes / blade loss is conducted;

[0063] ⑥ Regarding the influence of torque load, consider the rotor seizure under bird strike / blade loss conditions. Based on parameters such as rotor speed, rotor moment of inertia, and time, compare and analyze the maximum torque under the two conditions, or analyze and verify whether the torque load under bird strike conditions is within the engine's tolerable range;

[0064] ⑦ In terms of fire prevention, methods such as fragment trajectory and energy analysis under bird strike / blade loss conditions can be used to compare and analyze the differences in fuel tank damage and fuel pipe rupture under the two conditions;

[0065] ⑧ Conduct a comprehensive comparative analysis of the load effects under the above two test conditions to prove that the severity of the bird strike load is less severe than the blade containment and rotor imbalance tests. If successful, the comprehensive comparative analysis is completed;

[0066] ⑨ Based on the results of the containment capability verification, indirectly verify whether the engine's ability to swallow a single large bird meets the airworthiness requirements.

[0067] If the bird verification test is conducted, it includes two verification contents, including:

[0068] 1) Determine the test parameter requirements in accordance with airworthiness regulations and conduct bird swallowing capability verification of the mid-bird whole-aircraft test;

[0069] 2) perform additional integrity assessment verification;

[0070] If it is decided to conduct a small bird test verification, for engines that have not undergone the medium bird test or have failed the verification, the test parameter requirements will be determined in accordance with the airworthiness regulations, and a small bird whole-machine test verification will be conducted. The small bird whole-machine test verification method is the same as the verification method for the bird swallowing capability verification of the medium bird whole-machine test.

[0071] If it is decided to conduct a multi-feather large bird verification test, there are two verification methods, including:

[0072] 1) Conduct full-machine multi-feather bird testing and verification according to test parameter requirements, including:

[0073] ① Determine the test parameter requirements in accordance with the requirements for large birds with multiple feathers in FAR 33.76(d) of the airworthiness regulations, and conduct bird swallowing capability verification in the form of a whole-machine test.

[0074] ② Combined with the single large bird test. That is, the bird's weight, speed, and impact position shall be carried out in accordance with Article (1) of the Airworthiness Regulations FAR 33.76(b) for single large birds, and the test procedures and passing standards after swallowing the bird shall be carried out in accordance with Articles (4) and (5) of the Airworthiness Regulations FAR 33.76(d) for large birds with multiple feathers.

[0075] 2) Verify the whole machine with bird strike components, including:

[0076] ① Determine the test parameters in accordance with the requirements of FAR 33.76(d) for large feathered birds and conduct bird strike tests on fan components. The test pieces shall at least include components that have a critical impact on the swallowing ability of large feathered birds, such as fan blades and their connectors, fan inlet and outlet guide vanes, fan cap, fan disk and shaft, fan case, bearings and bearing seats, etc.;

[0077] ② Analyze the impact on the dynamics and performance of the entire aircraft, including but not limited to surge, flameout, and overrun, and prove that its impact on the requirements of clauses (4) and (5) of FAR 33.76(d) can be ignored;

[0078] ③ Install the components that have completed test ① into the engine and operate the engine to verify that they comply with the requirements of clauses (4) and (5) of FAR33.76(d).

[0079] According to different engine models, one of the appropriate verification methods is selected. When combined with a single large bird test, or a whole-machine verification of bird strike components is carried out, the resources required for the test are greatly reduced, the development cost is significantly reduced, the verification cycle is significantly shortened, and the development efficiency is significantly improved.

[0080] By adopting the above method, bird-swallowing airworthiness compliance verification can be carried out in different ways for birds of different weights. When conducting any single test, only targeted tests need to be carried out, and there is no need for the coordinated cooperation of multiple engine resources, test bench resources, debugging and test projection bird resources, human resources, etc. The method is comprehensive and systematic, which ensures that the verification is reasonable and effective, shortens the work cycle, saves test resources, and reduces development costs. The whole set of methods has been successfully applied in the airworthiness compliance verification of the bird-swallowing capability of turbofan engines.

[0081] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for verifying the airworthiness compliance of an aviation turbofan engine swallowing a bird, characterized in that: include: Obtain engine data and determine the type of test to be conducted, including improved / derivative engine verification tests and newly developed engine verification tests. The newly developed engine verification tests include single large bird verification tests, medium bird verification tests, small bird verification tests, and multi-feather large bird verification tests; To determine whether to conduct an improved / derivative engine verification test, first determine whether the corresponding prototype engine before the improvement / derivation has passed the bird swallowing airworthiness compliance verification; if so, conduct a comparative analysis between the improved / derivative engine and the prototype engine; if not, conduct the bird swallowing capability airworthiness compliance verification according to the newly developed engine verification test; Determine whether to conduct verification tests on newly developed engines and determine the specific test types; If it is determined that a single large bird verification test is to be conducted, then 1) the test parameters are determined in accordance with the airworthiness regulations and a single large bird whole aircraft test verification is conducted; or 2) a containment test equivalent method is used for verification; If it is determined that a mid-bird verification test is to be conducted, 1) the test parameters are determined in accordance with the airworthiness regulations and a mid-bird whole-machine test verification is conducted; 2) additional integrity assessment verification is conducted; If it is decided to conduct a small bird test verification, first determine whether it has passed the mid-bird swallowing capability verification; if so, then use the mid-bird verification results to verify the small bird capability; if not, determine the test parameter requirements in accordance with airworthiness regulations and conduct a small bird full-aircraft test verification; If it is determined that a multi-feather large bird verification test is to be conducted, then 1) a multi-feather large bird whole machine test verification is to be conducted in accordance with the test parameter requirements; or 2) a bird strike component string installation whole machine verification is to be conducted; During the improved / derivative engine verification test, after conducting a comparative analysis between the improved / derivative engine and the prototype engine, it is again determined whether the relevant design features are the same as or better than those of the prototype engine. If not, the bird-engagement capability airworthiness compliance verification is conducted in accordance with the engine verification test; If yes, then ask the user whether he agrees to be exempted from the test. If yes, then exempt him from the test. The comparative analysis between the improved / derivative engine and the prototype engine includes: Changes in fan blade configuration; Changes in the tangential speed of the fan blade tip; changes in the ability of the fan blade root to deflect in the mortise and tenon groove; changes in the axial distance between the fan blade and the boost stage inlet guide vane; changes in the inclination angle of the leading edge of the boost stage inlet guide vane; changes in the conical surface form of the fan cap; changes in the shape of the flow path at the boost stage outlet neck; changes in the VBV bleed valve; changes in the fan casing containment ring; and changes in the core engine design.

2. The method for verifying the airworthiness compliance of a turbofan engine when swallowing a bird according to claim 1, wherein: The containment test equivalent method includes: Determine test parameters in accordance with airworthiness regulations, conduct bird strike tests on fan components, and measure the axial load caused by bird strikes during component tests; Regarding the influence of axial load, based on the axial load measurement results in the bird strike component test, the analysis proves that it does not exceed the bearing load capacity. If successful, the axial load influence analysis is completed; To determine the effects of blade containment and rotor imbalance, the weight of fallen / broken blades from the bird strike component test, blade containment, and rotor imbalance tests was compared to determine the differences in their impact on casing containment. Based on the weight, center of gravity, and test speed of the fallen / broken blades, the centrifugal loads on the debris under the two test conditions were calculated and compared to determine the differences in the impact of the unbalanced loads. To address the impact of mounting section loads, dynamic simulation analysis based on the finite element model of the entire aircraft and mounting section safety strength tests were conducted to compare and analyze the differences in mounting section loads under bird strike / blade loss conditions. In view of the impact of surge loads, considering the impact of fan blade damage and bird body blocking the airflow channel, a comparative analysis of surge energy under the conditions of large bird strike / blade loss is conducted; To address the impact of torque load, consider rotor seizure under bird strike / blade loss conditions. Based on rotor speed, rotor moment of inertia, and time parameters, compare and analyze the maximum torque under the two conditions. Alternatively, analyze and verify whether the torque load under bird strike conditions is within the engine's tolerable range. In terms of fire prevention, the fragment trajectory and energy analysis methods under bird strike / blade loss conditions can be used to compare and analyze the differences in fuel tank damage and fuel pipe rupture under the two conditions; Conduct a comprehensive comparative analysis of load effects to demonstrate that bird strike loads are less severe than blade containment and rotor imbalance tests. If successful, the comprehensive comparative analysis is complete. Based on the results of the verification of the containment capability, it is indirectly verified whether the engine's ability to swallow a single large bird meets the airworthiness requirements.

3. The method for verifying the airworthiness compliance of an aviation turbofan engine when swallowing a bird according to claim 1, wherein: The multi-feather large bird complete machine test verification method includes: Determine the test parameters in accordance with the requirements for large birds with multiple feathers as specified in the airworthiness regulations, and verify the bird swallowing capability in the form of a complete aircraft test; The test is carried out in conjunction with the single large bird test. The bird's weight, speed and impact position are tested and verified in accordance with airworthiness regulations. The test procedures and passing standards after swallowing the bird are also tested and verified in accordance with airworthiness regulations.

4. The method for verifying the airworthiness compliance of a turbofan engine when swallowing a bird according to claim 1, wherein: The bird strike component serial installation whole machine verification method includes: Determine test parameters in accordance with airworthiness regulations and conduct bird strike tests on fan components. The test pieces shall at least include components that have a critical impact on the swallowing ability of large, feathered birds. Conduct impact analysis on overall machine dynamics and performance direction; The fan component that has completed the bird strike test is installed in series on the engine, and the whole engine is operated to verify whether it meets the airworthiness requirements.

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