Vibration coupling suppression method for aeroengine common load-bearing frame - dual-rotor system

Abstract

The present invention belongs to the technical field of the overall vibration of aero-engines, and particularly relates to a method for suppressing the vibration coupling of a common load-bearing frame - dual-rotor system of an aero-engine, including: inputting the structural parameters of the common load-bearing frame - dual-rotor system of the aero-engine; establishing a finite element model and calculating to obtain a Campbell diagram; selecting critical speed points within the operating speed range, calculating the transient dynamic response of the common load-bearing frame - dual-rotor system, and determining whether the transient dynamic response meets the requirements; performing an optimization design on the critical speed points that do not meet the requirements, and repeating the above steps until the transient dynamic responses of the critical speed points of the common load-bearing frame - dual-rotor system within the operating speed range all meet the requirements. The present invention realizes the effective suppression of the vibration coupling of the common load-bearing frame - dual-rotor system of a high-thrust-to-weight turbofan engine under complex working conditions, so that the aero-engine has a relatively stable working state within the operating speed range.

Description

Technical Field

[0001] The present invention belongs to the technical field of the overall vibration of aero-engines, and particularly relates to a method for suppressing the vibration coupling of a common load-bearing frame - dual-rotor system of an aero-engine. Background Technique

[0002] In the overall structure of a high-thrust-to-weight ratio turbofan engine, the adoption of a common load-bearing frame, especially the common load-bearing frame between turbine stages, can reduce the total number of load-bearing frames, effectively shorten the axial dimension of the engine, and reduce the mass of the engine. Therefore, the adoption of a common load-bearing frame between turbine stages has become a relatively common structural layout design scheme for aero-engines. However, due to the large change in the radial dimension of the common load-bearing frame between turbine stages, limited axial space, and being in a complex load environment of multiple rotors and multiple supports, there are serious vibration coupling problems in the dynamic response. The structural and dynamic design of the common load-bearing frame - dual-rotor system faces severe challenges.

[0003] The problem of suppressing the vibration coupling of the common load-bearing frame - dual-rotor system is a key technical difficulty in the structural layout design of a high-thrust-to-weight ratio turbofan engine using a common load-bearing frame between turbine stages. However, there is still a blank in the research on the independent design of the dynamic characteristics of the common load-bearing frame in China, and there is a lack of relevant basic theoretical methods. In engineering practice, there is a lack of experience in the structural layout and dynamic design of high-thrust-to-weight ratio turbofan engines. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a method for suppressing the vibration coupling of a common load-bearing frame - dual-rotor system of an aero-engine, so as to effectively suppress the vibration coupling of the common load-bearing frame - dual-rotor system of a high-thrust turbofan engine under complex working conditions, so that the aero-engine has a relatively stable working state within the working speed range.

[0005] The present invention is implemented as follows. A method for suppressing the vibration coupling of a common load-bearing frame - dual-rotor system of an aero-engine is provided. The common load-bearing frame is the common load-bearing frame between turbine stages of a high-thrust turbofan engine. The method includes the following steps:

[0006] Step S1: Input the structural parameters of the common load-bearing frame - dual-rotor system of the analyzed aero-engine;

[0007] Step S2: Establish a finite element model and calculate the Campbell diagram of the common load-bearing frame - dual-rotor system;

[0008] Step S3: Select dangerous speed points within the working speed range, calculate the transient dynamic response of the common load-bearing frame - dual-rotor system, and determine whether the transient dynamic response meets the requirements;

[0009] Step S4: When the requirements are not met, optimize the design of the common load-bearing frame, and repeat Step S2 and Step S3 until the transient dynamic responses of the common load-bearing frame-double rotor system within the operating speed range all meet the requirements.

[0010] Preferably, the structural parameters in Step S1 include material parameters, structural geometric parameters, and loads received during operation, etc.

[0011] Preferably, Step S2 is specifically as follows:

[0012] Based on the structural parameters extracted in Step S1, establish a finite element model, conduct a calculation and analysis of the resonance speed distribution characteristics of the common load-bearing frame-double rotor system, and obtain the Campbell diagram of the common load-bearing frame-double rotor system within the operating speed range.

[0013] Preferably, Step S3 is specifically as follows:

[0014] Based on the resonance speed distribution characteristics obtained in Step S2, select the intersection point of the speed line and the modal frequency line as the potential dangerous speed point. Considering that the rotational speeds of the two rotors are generally different, when determining the dangerous speed point, it is necessary to proceed according to the modal vibration mode. Specifically, if the vibration of a certain order of modal vibration mode is mainly that of the high-pressure rotor, then select the intersection point of the high-pressure rotor speed line and the positive precession frequency line of this order of mode as the dangerous point, which is consistent with the concept of the conventional critical speed point. In addition, since the common load-bearing frame can transmit the interaction excitation between the rotors, at the same time, select the intersection point of the low-pressure rotor speed line and the reverse precession frequency line of this order of mode as the dangerous point; calculate the transient dynamic response of the common load-bearing frame-double rotor system at the dangerous speed point, and judge whether the transient dynamic response meets the requirements for the long-term stable operation of the aeroengine according to the calculation results.

[0015] Preferably, Step S4 is specifically as follows:

[0016] Based on the judgment result of Step S3, if the transient dynamic response of a certain dangerous speed point does not meet the requirements, it is considered that there is a vibration coupling problem in the common load-bearing frame-double rotor system, and it is necessary to optimize the design of the common load-bearing frame. The optimization design includes improving the geometric configuration of the common load-bearing frame and designing vibration absorption and energy dissipation structures in the common load-bearing frame. After completing the optimization design, repeat Step S2 and Step S3 until the transient dynamic responses of the common load-bearing frame-double rotor system within the operating speed range meet the requirements for the long-term stable operation of the aeroengine.

[0017] Further preferably, the improvement of the geometric configuration of the common load-bearing frame is specifically as follows:

[0018] Change the common bearing housing for the two bearings in the common load-bearing frame to install the two bearings on the inner ring of the load-bearing frame through their respective bearing housings, conical shells, and flange edges respectively.

[0019] The above-mentioned improved design is to optimize the force transmission route in the shared load-bearing frame, reduce the intersection of the force transmission routes of the dynamic responses of the high-pressure rotor and the low-pressure rotor in the structure of the shared load-bearing frame, so as to reduce the interactive excitation of the dynamic responses between the high-pressure rotor and the low-pressure rotor, reduce the dynamic response of the dual-rotor - shared load-bearing frame system within the operating speed range, and effectively suppress the vibration coupling.

[0020] Further preferably, the vibration absorption - energy dissipation structure is designed in the shared load-bearing frame by designing the vibration absorption - energy dissipation structure of the shared load-bearing frame according to the frequency range corresponding to the critical speed point.

[0021] The design of the above-mentioned vibration absorption - energy dissipation structure absorbs and dissipates the vibration energy transmitted to the shared load-bearing frame by the high-pressure rotor and the low-pressure rotor respectively, so as to reduce the dynamic response near the critical speed point and effectively suppress the vibration coupling of the dual-rotor - shared load-bearing frame system.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] Based on the analysis of the vibration coupling phenomenon and mechanism, the present invention modifies the geometric configuration of the shared load-bearing frame and designs a vibration absorption - energy dissipation structure. Through these two aspects, the vibration coupling of the shared load-bearing frame - dual-rotor system is suppressed. The method flow is simple and clear, the operation process is clear and convenient, and a better optimized design result can be quickly obtained on the basis of relevant engineering experience. Using the optimized design method proposed by the present invention, during the development and design stage of the aero-engine model, by effectively suppressing the vibration coupling of the shared load-bearing frame - dual-rotor system, the dynamic response within the operating speed range is greatly reduced, and the structural and dynamic design of the shared load-bearing frame - dual-rotor system meeting the design requirements is realized, which has important engineering significance for promoting the overall structural design and model development progress of aero-engines. Description of the Drawings

[0024] Figure 1 It is the flow chart of the present invention;

[0025] Figure 2 It is the structural schematic diagram of the shared load-bearing frame - dual-rotor system;

[0026] Figure 3 It is the vibration coupling situation of the shared load-bearing frame - dual-rotor system;

[0027] Figure 4 It is the Campbell diagram of the shared load-bearing frame - dual-rotor system;

[0028] Figure 5 It is the original design scheme (1) and the geometric configuration improvement scheme (2) of the shared load-bearing frame;

[0029] Figure 6 Schematic diagram of the vibration absorption - energy dissipation structure in the shared load - bearing frame

[0030] Figure 7 Diagram showing the variation of the dynamic response of the shared load - bearing frame - dual - rotor system with rotational speed in different design schemes Specific implementation manners

[0031] To make the technical solutions of the present invention and their advantages clearer, the technical solutions of this application will be further described clearly and completely below in conjunction with the accompanying drawings. It can be understood that the specific embodiments described herein are only partial embodiments of this application, which are only used to explain this application and not to limit this application. It should be noted that for the sake of description, only the parts related to this application are shown in the drawings, and other related parts can refer to the general design. Without conflict, the embodiments in this application and the technical features in the embodiments can be combined with each other to obtain new embodiments.

[0032] Figure 1 The flowchart of the method for suppressing vibration coupling of the shared load - bearing frame - dual - rotor system of an aero - engine provided by the present invention is as follows. Below, reference is made to Figures 2 to 7 to further elaborate on this application in detail.

[0033] Adopting a shared load - bearing frame is a common overall structural layout scheme for high - thrust - to - weight - ratio turbofan engines. Figure 2 shows a schematic diagram of the structure of the shared load - bearing frame - dual - rotor system in a typical high - thrust - to - weight - ratio turbofan engine. In the figure, a is the low - pressure rotor, b is the high - pressure rotor, and c is the shared load - bearing frame.

[0034] Figure 3 is the deformation nephogram of the shared load - bearing frame - dual - rotor system at a certain operating rotational speed point, used to reflect the vibration coupling situation. There are often obvious vibration coupling problems between the high - pressure rotor, the low - pressure rotor and the shared load - bearing frame, which is the most severe dynamic problem faced by the overall structural layout scheme of adopting a shared load - bearing frame.

[0035] Figure 4It is the Campbell diagram of the shared load-bearing frame - dual-rotor system. Since the high-pressure rotor and the low-pressure rotor rotate in opposite directions, the intersection of the high-pressure speed line and the forward precession mode line, and the intersection of the low-pressure speed line and the backward precession mode line correspond to the resonance speed points that may be excited during the engine operation. Within the operating speed range, there are two intersections, indicating the potential for resonance to occur in the shared load-bearing frame - dual-rotor system near these two speeds. It should be specifically noted that not every intersection in the Campbell diagram will cause resonance, and further transient calculations are needed to obtain the dynamic response of the system at the corresponding speed for further confirmation. For the shared load-bearing frame - dual-rotor system of this embodiment, near the intersection of the high-pressure speed line and the forward precession mode line of the second mode, it is a critical speed point. Through calculation, it is found that near this speed point, the dynamic response at the bearing position exceeds the maximum value of the dynamic response required by the design, that is, it does not meet the requirements for the long-term stable operation of the aeroengine.

[0036] As Figure 5 shown, the geometric configuration of the shared load-bearing frame is optimized. Compared with Figure 5 the original design scheme in (1), Figure 5 in (2), the improvement of the geometric configuration is mainly to modify the shared bearing housing into individual bearing housings, and the two bearings are respectively installed on the inner ring of the load-bearing frame through the bearing housings, conical shells, and flange edges. Through the above modification, the dynamic responses transmitted from the two rotors to the load-bearing frame will be transmitted along their respective force transmission routes respectively, and will only intersect at the overlapping position between the conical shells. Compared with the shared bearing housing of the original scheme, the improved design scheme optimizes the force transmission route, delays and reduces the spatial range of the interaction between the dynamic responses of the high- and low-pressure rotors, thus achieving the effect of suppressing vibration coupling.

[0037] The method of optimizing the geometric configuration can appropriately adjust the modal frequencies of relevant modes, so as to achieve the effect of "avoiding resonance". However, the adjustment range of its modal frequencies is generally small, and in engineering, it often occurs that the adjusted modal frequencies are still close to the operating speed, making it difficult to achieve the ideal effect of "avoiding resonance". In this case, an absorption - energy dissipation structure can be designed and added to the shared load-bearing frame. As Figure 6 shown, in the figure, d represents the schematic diagram of the absorption - energy dissipation structure. It should be noted that the absorption - energy dissipation structure in the figure is only for illustration, and its specific structure and specific installation position need to be set according to specific situations. For example, a metal rubber absorption - energy dissipation structure and its design method are introduced in Patent CN118364588A, and relevant applications have been obtained in the relevant shared load-bearing frame structures.

[0038] By adjusting the parameters of the vibration absorption - energy dissipation structure, the dynamic response of the common load - bearing frame - dual - rotor system within a specific speed range can be reduced. By absorbing and dissipating the vibration energy at the dangerous operating speed in the common load - bearing frame structure, the vibration coupling of the high - and low - pressure rotors in the common load - bearing frame can be effectively reduced, thereby significantly decreasing the dynamic response, which meets the requirements for the long - term stable operation of aero - engines.

[0039] Figure 7 It shows the diagram of the variation of the dynamic response of the common load - bearing frame - dual - rotor system with the rotational speed in different design schemes. In the original design scheme, within the operating speed range, there is a resonance point that can be excited by the rotor rotation effect, resulting in the dynamic response not meeting the requirements. By improving the geometric configuration of the common load - bearing frame, the operating speed corresponding to the resonance phenomenon shifts, and the dynamic response within the operating speed range decreases significantly, but still does not fully meet the requirements. On the basis of the improved geometric configuration, after adding the vibration absorption - energy dissipation structure, the peak value of the resonance response decreases significantly, the dynamic response within the operating speed range decreases significantly and meets the requirements for the long - term stable operation of aero - engines. The vibration coupling suppression design method proposed by the present invention has achieved ideal results.

[0040] So far, the technical solution of this application has been described in combination with the preferred embodiments shown in the drawings. Those skilled in the art should understand that the protection scope of this application is obviously not limited to these specific embodiments. Without departing from the principle of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this application.

Claims

1. A method for suppressing vibration coupling of a common bearing frame-dual rotor system of an aircraft engine, characterized in that: The common load-bearing frame is a common load-bearing frame between turbine stages of a high-thrust turbofan engine, and the method comprises the following steps: Step S1: inputting structural parameters of the common load-bearing frame-dual rotor system of the aircraft engine to be analyzed; Step S2: Establish a finite element model and calculate the Campbell diagram of the common load-bearing frame-dual rotor system; Step S3: selecting a dangerous speed point within the working speed range, calculating the transient dynamic response of the common load-bearing frame-dual rotor system, and determining whether the transient dynamic response meets the requirements; Step S4: When the requirements are not met, the common load-bearing frame is optimized and steps S2 and S3 are repeated until the transient dynamic response of the common load-bearing frame-dual rotor system within the working speed range meets the requirements; the step S4 is specifically as follows: Based on the judgment result of step S3, if there is a transient dynamic response at a certain dangerous speed point that does not meet the requirements, it is considered that there is a vibration coupling problem in the common load-bearing frame-dual rotor system, and the common load-bearing frame needs to be optimized. The optimization design includes improving the geometric configuration of the common load-bearing frame and designing a vibration absorption-energy dissipation structure in the common load-bearing frame. After the optimization design is completed, steps S2 and S3 are repeated until the transient dynamic response of the common load-bearing frame-dual rotor system within the working speed range meets the requirements for long-term stable operation of the aircraft engine; The geometric configuration of the common load-bearing frame is specifically improved as follows: The common bearing seat of two bearings in the common load-bearing frame is changed into two bearings which are respectively installed on the inner ring of the load-bearing frame through their own bearing seats, cone shells and flange edges; The vibration absorption and energy dissipation structure is designed in the common load-bearing frame according to the frequency range corresponding to the dangerous rotation speed point.

2. The method for suppressing vibration coupling of a common bearing frame-dual rotor system of an aircraft engine according to claim 1, characterized in that: The structural parameters in step S1 include material parameters, structural geometric parameters and loads received during the working process.

3. The method for suppressing vibration coupling of a common bearing frame-dual rotor system of an aircraft engine according to claim 1, characterized in that: The step S2 is specifically as follows: Based on the structural parameters extracted in step S1, a finite element model is established, and the resonant speed distribution characteristics of the common load-bearing frame-dual rotor system are calculated and analyzed to obtain the Campbell diagram of the common load-bearing frame-dual rotor system within the operating speed range.

4. The method for suppressing vibration coupling of a common bearing frame-dual rotor system of an aircraft engine according to claim 3, characterized in that: The step S3 is specifically as follows: Based on the resonant speed distribution characteristics obtained in step S2, the intersection of the speed line and the modal frequency line is selected as a potential dangerous speed point, and the transient dynamic response of the shared load-bearing frame-dual rotor system at the dangerous speed point is calculated. According to the calculation results, it is judged whether the transient dynamic response meets the requirements for long-term stable operation of the aircraft engine.

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