Aero-engine rotor bending critical rotating speed adjusting method based on modal shape

Abstract

The embodiment of the invention provides an aero-engine rotor bending critical rotating speed adjusting method based on a modal shape, and relates to the field of aero-engine high-pressure rotors. The objective of the invention is to improve the problems of complex process and high cost of engine rotor bending critical speed adjustment by changing elastic support rigidity and rotor structure parameters. Comprising the steps that the bending critical rotating speed of the engine rotor is adjusted by adjusting the local mass of a deformation sensitive area of the engine rotor; wherein the deformation sensitive area refers to an area with the maximum bending mode deformation. The bending critical rotation speed of the engine rotor is controllably adjusted by adjusting the mass in a deformation sensitive area of the engine rotor, the bending critical rotation speed can be simply and efficiently adjusted and subjected to test verification through the adjusting mode, and the bending critical rotation speed design margin of the engine can be conveniently obtained.

Description

Technical Field

[0001] This invention relates to the field of high-pressure rotors for aero-engines, and more specifically, to a method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes. Background Technology

[0002] Rotor dynamics design for aero-engines is one of the core technologies in aero-engine design. Properly configuring the critical speed of the rotor support system is a crucial prerequisite for ensuring the safe and reliable operation of the engine. For high-pressure rotors in aero-engines, certain design principles must be followed when designing critical speeds. One very important principle is that the rotor's bending critical speed should be adjusted above the engine's maximum operating speed, with a certain safety margin. The bending critical speed means that the rotor exhibits a large bending vibration mode. At this speed, the rotor's bending strain energy is usually relatively high. On the one hand, this type of vibration mode is highly sensitive to unbalanced excitation; on the other hand, a large portion of the engine's strain energy is concentrated on the rotor, while the deformation of stator components is small, resulting in less participation in vibration and less absorption of vibration energy. Therefore, it is essential to avoid the bending critical speed range within the operating speed range.

[0003] As the thrust-to-weight ratio of aero engines continues to increase, there is a growing demand for engines to meet safe operation requirements while maintaining a lighter structural weight. The static strength of the rotor limits the maximum operating speed of the engine rotor, and the improved maturity of rotor dynamics analysis methods has resulted in a smaller discrepancy between the analytical and experimental results for critical speeds. Therefore, whether the safety margin for the bending critical speed design can be reduced, and to what extent, needs to be verified through experiments. Conventional methods for adjusting the critical speed of the engine rotor-support system include adjusting the stiffness of the elastic support and changing rotor structural parameters to adjust rotor stiffness. However, the adjustable range of the elastic support stiffness is limited, and replacing the elastic support is a complex and time-consuming process; changing rotor structural parameters requires reprocessing and replacing the rotor, which is costly. Summary of the Invention

[0004] The following provides a brief overview of one or more aspects to offer a basic understanding of them. This overview is not an exhaustive summary of all conceived aspects, nor is it intended to identify key or decisive elements of all aspects, nor to define the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form to prepare for the more detailed descriptions that follow.

[0005] The objectives of this invention include, for example, providing a method for adjusting the bending critical speed of an aero-engine rotor based on mode shape, which can improve the problems of complex procedures and high costs associated with adjusting the bending critical speed of an engine rotor by changing the elastic support stiffness and rotor structural parameters.

[0006] The embodiments of the present invention can be implemented as follows:

[0007] An embodiment of the present invention provides a method for adjusting the bending critical speed of an aero-engine rotor based on mode shape, comprising: adjusting the bending critical speed of the engine rotor by adjusting the local mass of the deformation-sensitive region of the engine rotor; wherein, the deformation-sensitive region refers to the region of maximum bending mode deformation.

[0008] In addition, the method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes provided in the embodiments of the present invention may also have the following additional technical features:

[0009] Optionally, the step of adjusting the critical bending speed of the engine rotor by adjusting the local mass of the deformation-sensitive region of the engine rotor includes:

[0010] By performing bending modal analysis on the engine rotor, the deformation-sensitive region of the engine rotor was obtained. A simulation analysis model of the engine rotor's critical speed was established. By adding adjustment components of different masses to the deformation-sensitive region of the engine rotor, bending critical speed analysis was performed to obtain the bending critical speed and design margin corresponding to different masses. Based on the simulation analysis results of the engine rotor's critical speed, engine rotor dynamic characteristic tests were conducted to verify the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and the sensitivity curve of the rotor's bending critical speed and the local mass of the deformation-sensitive region was obtained.

[0011] Optionally, the step of obtaining the deformation-sensitive region of the engine rotor through engine rotor bending modal analysis includes:

[0012] Through bending modal analysis of the high-pressure rotor of an aero-engine, the deformation-sensitive region of the high-pressure rotor is found to be the front end of the front shaft diameter.

[0013] Optionally, the adjusting component is fixed to the front end of the front axle diameter via an adapter shaft, and the front end of the front axle diameter is provided with multiple locating pin holes along the circumferential direction; the outer ring of the adapter shaft is provided with multiple locating holes along the circumferential direction, and the inner ring of the adapter shaft is provided with multiple threaded holes along the circumferential direction. The locating holes correspond to the locating pin holes and are fixed by locking nuts after being positioned by locating pins. The locking nuts are threadedly connected to the front end of the front axle diameter; the adjusting component is provided with multiple bolt mounting holes along the circumferential direction, and the bolt mounting holes correspond to the threaded holes and are fixed by screws.

[0014] Optionally, the adjusting component is an adjusting shaft; the adjusting shaft includes a first shaft segment, one end of which is circumferentially provided with a connecting flange, and the connecting flange is provided with a plurality of bolt mounting holes along the circumferential direction; the axial length of the first shaft segment is a variable for different mass adjustments.

[0015] Optionally, the adjusting shaft includes a second shaft segment, the diameter of which is greater than that of the first shaft segment. The second shaft segment is coaxially fixed with the first shaft segment, and the second shaft segment is located at the end of the first shaft segment away from the connecting flange. The diameter and axial length of the second shaft segment are both variables for different mass adjustments.

[0016] Optionally, the step of establishing a simulation analysis model for the critical speed of the engine rotor, by adding adjustment components of different masses to the deformation-sensitive area of ​​the engine rotor, and performing bending critical speed analysis to obtain the bending critical speed and design margin corresponding to different masses, includes:

[0017] Establish a critical speed analysis model for the engine rotor; calculate the bending critical speed Nc0 and the design margin M0 from the maximum operating speed Nwmax under the initial operating condition 0, where M0 = (Nc0 - Nwmax) / Nwmax; calculate the bending critical speed Ncmin and the minimum design margin Mmin from the maximum operating speed Nwmax under the condition of adding the maximum mass adjustment component, where Mmin = (Ncmin - Nwmax) / Nwmax, and the minimum design margin Mmin ≤ -10%; calculate the bending critical speed Nci and the design margin Mi from the maximum operating speed Nwmax obtained by adding different mass adjustment components under different operating conditions, Mi = (Nci - Nwmax) / Nwmax; based on Mmin ≤ Mi < M0, obtain the bending critical speed and design margin corresponding to different masses.

[0018] Optionally, the step of conducting engine rotor dynamic characteristic tests based on the simulation analysis results of the engine rotor critical speed, verifying the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and obtaining the sensitivity curve of the rotor bending critical speed and the local mass of the deformation-sensitive region includes:

[0019] The simulation analysis results of the critical speed of the engine rotor were verified by physical verification. A frequency sweep test was carried out under the initial working condition 0 state, and frequency sweep tests were carried out on the engine rotor with adjustment parts of different masses in ascending order to obtain the bending critical speed within the maximum working speed range. The sensitivity curve was plotted based on the relationship between the obtained bending critical speed and the local mass of the deformation sensitive area.

[0020] Optionally, the step of conducting engine rotor dynamic characteristic tests based on the simulation analysis results of the engine rotor critical speed, verifying the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and obtaining the sensitivity curve of the rotor bending critical speed and the local mass of the deformation-sensitive region further includes:

[0021] The deviation value is calculated between the bending critical speed obtained from the actual test of the engine rotor dynamic characteristics and the bending critical speed obtained from the simulation analysis of the engine rotor critical speed; the design margin is adjusted according to the deviation value.

[0022] Optionally, the initial operating condition 0 state is the state in which the engine rotor does not have any adjustment components added.

[0023] The beneficial effects of the modal vibration mode-based method for adjusting the critical bending speed of an aero-engine rotor according to embodiments of the present invention include, for example:

[0024] The method for adjusting the bending critical speed of an aero-engine rotor based on mode shape includes: adjusting the bending critical speed of the engine rotor by adjusting the local mass of the deformation-sensitive region of the engine rotor; wherein, the deformation-sensitive region refers to the region with the maximum bending mode deformation.

[0025] In the deformation-sensitive region of the engine rotor, the bending critical speed of the engine rotor can be controlled by adjusting the mass. This adjustment method can simply and efficiently adjust and test the bending critical speed, making it easy to obtain the design margin of the engine's bending critical speed. Attached Figure Description

[0026] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0027] Figure 1 This is a schematic diagram of a high-voltage rotor structure provided in an embodiment of the present invention;

[0028] Figure 2 This is an example of the bending mode vibration shape of the high-pressure rotor of an engine provided in an embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the assembly of the adjustment shaft, the adapter shaft, and the front end of the front axle diameter provided in an embodiment of the present invention;

[0030] Figure 4 A schematic diagram of the front axle mounting interface structure provided in an embodiment of the present invention;

[0031] Figure 5 This is a schematic diagram of the structure of the adapter shaft provided in an embodiment of the present invention;

[0032] Figure 6 This is a schematic diagram of the structure of the first type of adjusting shaft provided in an embodiment of the present invention;

[0033] Figure 7 This is a schematic diagram of the structure of the second type of adjustment shaft provided in an embodiment of the present invention;

[0034] Figure 8 This is a schematic diagram of the amplitude change when the rotor passes the critical point, provided in an embodiment of the present invention.

[0035] Figure 9 This is a schematic diagram of the phase change when the rotor is over the critical point, provided in an embodiment of the present invention.

[0036] Figure 10 The rotor bending criticality and lumped mass sensitivity curves provided for embodiments of the present invention;

[0037] Figure 11 A flowchart of a method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes, provided in an embodiment of the present invention;

[0038] Figure 12 The flowchart is a method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes, provided in an embodiment of the present invention.

[0039] Icons: 1-High-pressure rotor; 2-Front pivot bearing; 3-Rear pivot bearing; 4-Front shaft diameter; 41-Internal thread; 42-Mounting edge; 43-Locking pin hole; 51-Adapter shaft; 511-First mounting edge; 512-Second mounting edge; 513-Threaded hole; 514-Locking hole; 52-Adjusting shaft; 521-Connecting flange; 522-Bolt mounting hole; 53-Locking pin; 54-Locking nut; 523-End face threaded hole; 55-Fixing screw. Detailed Implementation

[0040] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. It should be noted that the aspects described below with reference to the accompanying drawings and specific embodiments are merely exemplary and should not be construed as limiting the scope of protection of the present invention in any way.

[0041] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," "outer," or "vertical" appear, the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use, and does not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0042] At the same time, it should be noted that the terms "first" and "second" are used only for distinguishing descriptions and should not be interpreted as indicating or implying relative importance.

[0043] In the description of this invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an integral connection, or a detachable connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or a connection within two components, etc. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0044] The following is combined with Figures 1 to 12 The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes provided in this embodiment is described in detail.

[0045] Please refer to Figure 1 and Figure 2 The present invention provides a method for adjusting the bending critical speed of an aero-engine rotor based on mode shape, comprising: adjusting the bending critical speed of the engine rotor by adjusting the local mass of the deformation-sensitive region of the engine rotor; wherein, the deformation-sensitive region refers to the region with the maximum bending mode deformation.

[0046] Reference Figure 1 The high-pressure rotor 1 of the engine is usually a disc-shaft structure with front and rear double support points. The front support bearing 2 is a ball bearing, the rear support bearing 3 is usually a roller bearing, and the front shaft diameter 4 is the shaft at the front end of the rotor where the front support bearing is installed and connected to the rotor stage 1 disc.

[0047] It should be noted that "critical speed" is the rotational speed at which the lateral vibration of the rotor caused by unbalanced excitation reaches its maximum value; it is called the critical speed of the rotor-support system. The critical speed is an inherent property of the rotor-support system, determined by its mass, stiffness, and damping. In a rotating system, the centers of mass of each segment of the rotor cannot be perfectly aligned with the axis of rotation; therefore, lateral disturbances occur when the rotor rotates. At certain speeds, these lateral disturbances can cause strong vibrations in the system; these speeds are the critical speeds. "Bending mode" refers to the relative vibration displacement between different positions of a structure at a modal frequency. It characterizes the vibration mode of the structure at a specific frequency. Modal modes correspond one-to-one with modal frequencies and are inherent characteristics of the structure. The bending mode is one such mode, characterized by rotor bending, a single crest, and two intersections with the rotor axis.

[0048] In the deformation-sensitive region of the engine rotor, the bending critical speed of the engine rotor can be controlled by adjusting the mass. This adjustment method can simply and efficiently adjust and test the bending critical speed, making it easy to obtain the design margin of the engine's bending critical speed.

[0049] Among them, the "deformation-sensitive area" is obtained by analyzing the bending mode of the engine rotor, examining the modal analysis results, especially the mode shape diagram of the bending mode, and identifying the area with large deformation.

[0050] Reference Figure 2 and 11 In this embodiment, the step of adjusting the critical bending speed of the engine rotor by adjusting the local mass of the deformation-sensitive area of ​​the engine rotor includes:

[0051] Step a: Obtain the deformation-sensitive region of the engine rotor through bending mode analysis;

[0052] Step b: Establish a simulation analysis model of the critical speed of the engine rotor. By adding adjustment parts of different masses to the deformation-sensitive area of ​​the engine rotor, bending critical speed analysis is performed to obtain the bending critical speed and design margin corresponding to different masses.

[0053] Step c: Based on the simulation analysis results of the engine rotor critical speed, conduct engine rotor dynamic characteristic tests to verify the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and obtain the sensitivity curve of the rotor bending critical speed and the local mass of the deformation sensitive area.

[0054] By establishing a finite element model of the engine rotor, rotor modal or critical speed analysis is performed. Based on the bending mode shape, a region with large rotor deformation is identified. The mass change in this region will have a significant impact on the bending critical speed. This region is the deformation-sensitive region.

[0055] In the engine rotor critical speed simulation analysis, the bending critical speed and design margin under different adjustment shafts 52 are obtained by adjusting the structure and weight of the adjustment shaft 52 in the analysis model. In the rotor dynamic characteristic test, since the rotor structural strength limits the maximum speed that the rotor can actually operate at, the bending critical speed of the rotor can be controlled and adjusted by installing adjustment shafts 52 of different weights at the front end of the rotor. When the installed adjustment shaft 52 has a sufficiently large mass, the rotor bending critical speed can be adjusted to the maximum speed range, and the rotor bending critical speed can be identified by vibration response. By comparing the experimentally measured bending critical speed with the model analysis bending critical speed, the design margin that the rotor bending critical speed must meet can be obtained, thereby optimizing the design margin requirements in the design criteria. At the same time, based on the verification results, a relationship curve between the local concentrated mass of the deformation-sensitive area and the bending critical speed can be established. According to this curve, the rotor mass can be accurately controlled and designed according to the bending critical speed design requirements.

[0056] In essence, this involves building a model and assembling adjustment components of varying masses in the deformation-sensitive region. Bending critical speed analyses are then performed to obtain the bending critical speeds and design margins corresponding to different masses. The model is then manufactured, and the engine rotor is mounted on a test bench with adjustment components of varying masses. Rotor dynamic characteristic tests are conducted to obtain the bending critical speeds corresponding to different masses. These speeds are then compared with the bending critical speeds obtained from the model analysis to determine the deviation. The design margins are adjusted based on this deviation, and a sensitivity curve can be plotted using the rotor bending critical speeds obtained from the tests and the local mass of the deformation-sensitive region.

[0057] Reference Figure 1 and Figure 3 In this embodiment, step a, the step of obtaining the deformation-sensitive region of the engine rotor through engine rotor bending mode analysis, includes: obtaining the deformation-sensitive region of the high-pressure rotor of the aero-engine as the front end of the front shaft diameter 4 through bending mode analysis of the aero-engine high-pressure rotor.

[0058] Taking a high-pressure rotor of an aero-engine as an example, the location of the largest bending modal deformation is at the front end of the front shaft diameter 4. For a high-pressure rotor of an aero-engine, the mode shape corresponding to the bending critical speed is a two-node overall rotor bending. Based on the bending mode shape, the area of ​​largest rotor deformation is usually located at the front end of the rotor, and the rotor bending critical speed is most sensitive to the mass of the front end. While keeping the main rotor structure unchanged, an installation interface structure is designed only at the front end of the rotor's front shaft diameter 4, and adjustment shafts 52 of different weights are designed.

[0059] Reference Figure 3 , Figure 4 , Figure 5 and Figure 6 In this embodiment, the adjusting component is fixed to the front end of the front axle diameter 4 via the adapter shaft 51. The front end of the front axle diameter 4 is provided with multiple positioning pin holes 43 along the circumferential direction. The outer ring of the adapter shaft 51 is provided with multiple positioning holes 514, and the inner ring of the adapter shaft 51 is provided with multiple threaded holes 513. The positioning holes 514 correspond to the positioning pin holes 43 and are positioned by positioning pins 53, and are then abutted and fixed by locking nuts 54. The locking nuts 54 are threadedly connected to the front end of the front axle diameter 4. The adjusting component is provided with multiple bolt mounting holes 522 along the circumferential direction. The bolt mounting holes 522 correspond to the threaded holes 513 and are fixed by screws.

[0060] The front axle diameter 4 is modified by adding a mounting edge 42, an internal thread 41, and a positioning pin hole 43 at the front end. The adapter shaft 51 is designed so that it can be connected to the front axle diameter 4 through the "first mounting edge 511 + positioning hole 514" and connected to the adjustment shaft 52 through the "second mounting edge 512 + threaded hole 513" structure.

[0061] The outer ring of the adapter shaft 51 is fixed to the locating pin hole 43 at the front end of the front shaft diameter 4 through multiple locating holes 514, and the inner ring of the adapter shaft 51 is fixed to the bolt mounting hole 522 of the adjusting component through multiple threaded holes 513. The locking nut 54 is threaded to the inner side of the front end of the front shaft diameter 4, and one end of the locking nut 54 abuts against the locating pin 53 inserted into the locating hole 514 and the locating pin hole 43. The locking nut 54 is located between the front end of the front shaft diameter 4 and the adjusting component.

[0062] Specifically, the front end structure of the front axle diameter 4 includes an internal thread 41, a mounting edge 42, and a locating pin hole 43. The structure of the adapter shaft 51 includes a first mounting edge 511, a second mounting edge 512, a threaded hole 513, and a locating hole 514. The structure of the adjusting shaft 52 includes a connecting flange 521, a bolt mounting hole 522, and a threaded hole 513. The adapter shaft 51 is mounted on the front axle diameter 4, and radially fitted with its respective mounting edge 42 and the first mounting edge 511, typically using a small clearance fit or transition fit. The two parts are circumferentially positioned by two locating pins 53. The adapter shaft 51 is axially compressed and fixed by a lock nut 54. The adjusting shaft 52 has multiple bolt mounting holes 522 circumferentially designed, allowing adjusting shafts 52 of different weights to be mounted on the adapter shaft 51 and fixed by a "stop fit + multiple fixing screws 55". The structural form of the adjusting shaft 52 is not unique; various structural designs can be made according to weight requirements, but the ease of installation of the parts must be considered. In addition to bolt mounting holes 522, the connecting flange 521 of the adjusting shaft 52 can also have set screw holes. By rotating the screw into the set screw hole until it abuts the adapter shaft 51, and continuing to rotate, the adjusting shaft 52 and the adapter shaft 51 can be separated axially, which facilitates the replacement of the adjusting shaft 52. A threaded hole 523 can also be designed at the front end of the adjusting shaft 52 to facilitate the installation of a puller to remove the adjusting shaft 52 from the adapter shaft 51.

[0063] It should also be noted that the initial working condition 0 mentioned in the text refers to the state in which only the adapter shaft 51 is installed, and no adjustment parts are installed.

[0064] Reference Figure 6 In this embodiment, the adjusting component is an adjusting shaft 52; the adjusting shaft 52 includes a first shaft section, one end of which is provided with a connecting flange 521 in the circumferential direction, and the connecting flange 521 is provided with a plurality of bolt mounting holes 522 in the circumferential direction; the axial length of the first shaft section is a variable for different mass adjustments.

[0065] One end of the adjusting shaft 52 is connected to the adapter shaft 51 via a connecting flange 521. Considering the installation space limitations of the fixing screw 55, the diameter D of the first shaft segment cannot exceed the maximum size of the installation space limit, but the diameter D can be reduced. After the size D is determined, the weight can also be adjusted by controlling the axial length L of the first shaft segment; the adjustment method is simple and stable.

[0066] Reference Figure 7 In this embodiment, the adjusting shaft 52 includes a second shaft segment with a diameter greater than that of the first shaft segment. The second shaft segment is coaxially fixed with the first shaft segment and is located at the end of the first shaft segment away from the connecting flange 521. The diameter and axial length of the second shaft segment are variables that are adjusted by different masses.

[0067] To allow sufficient space for the installation of the fixing screw 55, the diameter of the first shaft segment is smaller than that of the second shaft segment. When the weight adjustment of the first shaft segment cannot meet the critical bending speed analysis, the weight can be adjusted by setting the second shaft segment and adjusting its diameter and axial length.

[0068] Reference Figure 6 and Figure 7 Given a fixed diameter D, a simpler method of adjusting weight by controlling the axial length L of the first shaft is preferred. If installation space is limited, the adjusting shaft 52 can also be designed with a variable diameter. While ensuring convenient assembly of parts, the different weights of the adjusting shaft 52 can be controlled by adjusting the dimensions D1, D2, L1, and L2.

[0069] In this embodiment, step b, establishing a simulation analysis model for the critical speed of the engine rotor, involves adding adjustment components of different masses to the deformation-sensitive area of ​​the engine rotor and performing bending critical speed analysis to obtain the bending critical speed and design margin corresponding to different masses.

[0070] Step b1: Establish a critical speed analysis model for the engine rotor;

[0071] Step b2, calculate the critical bending speed Nc0 under the initial working condition 0 and the design margin M0 of the distance from the maximum working speed Nwmax, where M0 = (Nc0 - Nwmax) / Nwmax;

[0072] Step b3: Calculate the critical bending speed Ncmin and the distance to the maximum working speed Nwmax under the condition of increasing the maximum mass adjustment component, and obtain the minimum design margin Mmin, where Mmin=(Ncmin-Nwmax) / Nwmax, and the minimum design margin Mmin≤-10%.

[0073] Step b4: Calculate the critical bending speed Nci and the design margin Mi of the distance to the maximum working speed Nwmax obtained from the analysis of adding different mass adjustment parts under different working conditions, Mi = (Nci - Nwmax) / Nwmax;

[0074] Step b5: Based on Mmin≤Mi<M0, obtain the bending critical speed and design margin corresponding to different masses.

[0075] It should be noted that the operating speed Nw is a known operating speed range, from the minimum value to the maximum value.

[0076] Calculate the bending critical speed Nc0 and the design margin M0 under the initial operating condition 0. The bending critical speed Nc0 needs to be obtained through rotor dynamics analysis or tests. The range of the operating speed Nw is known, and the maximum operating speed Nwmax can be obtained. Calculate the design margin M0 = (Nc0 - Nwmax) / Nwmax.

[0077] Calculate the bending critical speed Nci and the design margin Mi under different operating conditions i. For each operating condition i (i.e., different structures of the adjusting shaft 52), the bending critical speed Nci needs to be recalculated. The design margin Mi = (Nci - Nwmax) / Nwmax, and Mi < M0.

[0078] Carry out the design of multiple groups of different adjusting shaft 52 groups and the analysis of the bending critical speed. In order to ensure the feasibility of experimental verification, it is necessary to design multiple groups of different structures of the adjusting shaft 52. Under the maximum weight group of the adjusting shaft 52, it is required that the minimum design margin Mmin ≤ -10% (i.e., Mmin ≤ -0.1). The magnitude of the minimum design margin Mmin depends on the accuracy of the analysis method, and the specific value of Mmin can be adjusted according to the accuracy of the analysis method and actual requirements.

[0079] The relationship satisfied by the design margins is Mmin ≤ Mi < M0, and Mi is distributed as evenly as possible at equal intervals. This means that when designing the structure of the adjusting shaft 52, an attempt should be made to make the design margins under each operating condition evenly distributed.

[0080] In this embodiment, in step c, according to the simulation analysis results of the engine rotor critical speed, an engine rotor dynamic characteristic test is carried out, and the bending critical speed and design margin corresponding to different masses obtained from the model analysis are verified. The steps for obtaining the sensitivity curve of the bending critical speed of the rotor and the local mass in the deformation sensitive area include:

[0081] Step c1, physically verify the simulation analysis results of the engine rotor critical speed, carry out a sweep frequency test under the initial operating condition 0, and for the engine rotor assembled with different masses in ascending order, carry out sweep frequency tests respectively to obtain the bending critical speed within the maximum operating speed range;

[0082] Step c2, draw a sensitivity curve according to the relationship between the obtained bending critical speed and the local mass in the deformation sensitive area.

[0083] Rotor dynamic characteristic tests are conducted by manufacturing the engine rotor, adapter shaft 51, and multiple groups of adjusting shafts 52 based on the critical speed simulation analysis results. Through actual simulation model analysis on a test bench, rotor dynamic characteristic tests are performed on adjusting shafts 52 of different masses under different operating conditions to determine whether a trend of gradually increasing vibration and phase change occurs near the maximum operating speed. Specific details are provided in [reference needed]. Figure 8 and Figure 9 Near the critical bending speed, the vibration amplitude gradually increases. At the same time, the phase flips by 180° near the critical speed. The critical bending speed appears within the maximum working speed range, and the critical bending speed under this mass condition is obtained. If the critical bending speed does not fall within the maximum working speed range, the critical bending speed cannot be obtained. Adjusting the adjustment shaft with different masses in sequence and performing frequency sweep tests, the critical bending speeds corresponding to different masses are obtained.

[0084] Specifically, determining whether the rotor's bending critical speed falls within its maximum operating speed range involves analyzing the vibration of the engine's high-pressure rotor. Particular attention should be paid to the vibration behavior near the bending critical speed. Near the bending critical speed, the vibration amplitude typically increases gradually, and the phase will flip by 180° near the critical speed. This is a crucial indicator of whether the rotor is approaching or has reached its bending critical speed. By analyzing the vibration data, it can be determined whether the rotor's bending critical speed has fallen within its maximum operating speed range.

[0085] Conduct a frequency sweep test under operating condition 0: Under operating condition 0 (usually the initial or standard operating condition), perform a frequency sweep test on the rotor. The frequency sweep test involves gradually changing the rotor speed and observing and recording its vibration at different speeds. Pay particular attention to whether there is a trend of gradually increasing vibration and phase changes near the maximum operating speed. These changes may indicate that the rotor is approaching or reaching its bending critical speed.

[0086] The rotor state was changed by adjusting the weight of shaft 52, and a frequency sweep test was conducted: different groups of adjusting shaft 52 structures were installed in order of increasing weight. A frequency sweep test was performed on the rotor under each adjusting shaft 52 structure, and the vibration was observed and recorded. This continued until a trend of gradually increasing vibration and phase change appeared within the maximum operating speed range of operating condition j (a specific operating condition).

[0087] Reference Figure 10 Based on the analysis and experimental verification results, a sensitivity curve between the rotor's bending critical speed and concentrated mass can be plotted. According to this curve, the rotor mass can be accurately controlled and designed according to the design requirements of the bending critical speed.

[0088] In this embodiment, step c1, which involves conducting engine rotor dynamic characteristic tests based on the simulation analysis results of the engine rotor critical speed, verifying the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and obtaining the sensitivity curve of the rotor bending critical speed and the local mass of the deformation-sensitive region, further includes:

[0089] Step c11: Calculate the deviation between the bending critical speed obtained from the actual test of the engine rotor dynamic characteristics and the bending critical speed obtained from the simulation analysis of the engine rotor critical speed.

[0090] Step c12: Adjust the design margin based on the deviation value.

[0091] The deviation between the calculated value (Ncj) and the measured value (Ntj) of the bending critical speed under operating condition j is calculated. Ncj is the model analysis value, and Ntj is the measured value of the rotor dynamic characteristic analysis. The formula for calculating the deviation value Δ is (Ncj-Ntj) / Ntj×100%. The design margin can be corrected according to the magnitude of the deviation value Δ.

[0092] Further validation of the analysis method and plotting of sensitivity curves: If necessary, a heavier adjusting shaft 52 can be used to obtain rotor bending critical speed data under more operating conditions. Based on these multi-condition measured data, the analysis method is validated. This helps ensure the accuracy and reliability of the analysis method. Based on the analysis and experimental validation results, a sensitivity curve of rotor bending critical speed versus concentrated mass is plotted. This curve can visually show the trend of rotor bending critical speed with the change of concentrated mass (such as the weight of adjusting shaft 52).

[0093] This sensitivity curve allows for precise control and design of rotor mass according to the bending critical speed design requirements. This helps optimize rotor performance and ensure its stability and safety under various operating conditions.

[0094] In this embodiment, the initial operating condition 0 is the state where the engine rotor has no additional adjusting components. Whether in simulation model analysis or physical rotor dynamic characteristic test, the initial operating condition 0 refers to the state where only the adapter shaft 51 is installed at the front end of the front shaft diameter 4, and the adjusting shaft 52 is not installed.

[0095] Reference Figure 11 and Figure 12 According to the method for adjusting the critical bending speed of an aero-engine rotor based on mode shape provided in this embodiment, the working principle of the method for adjusting the critical bending speed of an aero-engine rotor based on mode shape includes:

[0096] Rotor bending modal analysis: A finite element model of the engine rotor is established, and rotor modal or critical speed analysis is performed. Based on the bending mode shape, regions with large rotor deformation are identified. The mass change in these regions has a significant impact on the bending critical speed. Taking the high-pressure rotor of an aero-engine as an example, the location of large bending modal deformation is at the front end of the front shaft diameter 4.

[0097] Rotor modification design: Modify the front shaft diameter 4 by adding a mounting edge 42, internal thread 41 and locating pin hole 43 at the front end;

[0098] Adjustment shaft 52 design: Design multiple groups of adjustment shaft 52 structures, with different groups corresponding to different adjustment shaft 52 weights.

[0099] A finite element model was established, and a bending critical speed analysis was conducted. First, the bending critical speed Nc0 and the design margin M0 from the maximum operating speed Nwmax were calculated under initial operating condition 0. Operating condition 0 refers to the rotor state with only the adapter shaft 51 installed at the front shaft diameter 4, without the adjustment shaft 52 structure installed in the initial operating condition. M0 = (Nc0 - Nwmax) / Nwmax. Different groups of adjustment shaft 52 structures were added to the finite element model, denoted as group i. The bending critical speed Nci and the design margin Mi from the maximum operating speed Nwmax were calculated under different operating conditions i. The design margin Mi after adding the adjustment shaft 52 is < M0. Considering the potential deviation between the analysis results and experimental measurements, to ensure experimental verification of the bending critical speed, several different adjustment shaft 52 groups should be designed and analyzed for bending critical speeds. It is recommended that, under the largest adjustment shaft 52 weight group, the minimum design margin Mmin from the maximum operating speed Nwmax should be ≤ -10%. The minimum design margin Mmin depends on the accuracy of the engine rotor critical speed analysis method and can be adjusted as needed. The design margin conforms to the following relationship: Mmin ≤ Mi < M0, and Mi is distributed as evenly as possible.

[0100] To verify whether the adjustment shaft group and weight meet the verification requirements, adjustment shafts of different masses are assembled sequentially and bending modal analysis is performed. If the critical bending speed falls within the maximum speed range, the verification requirements are met, and the next step is to proceed to the prototype manufacturing of the part. If not, the next adjustment shaft of different masses is replaced and bending modal analysis is performed. The adjustment shafts corresponding to the critical bending speeds falling within the maximum operating speed range are sequentially selected for prototype manufacturing of the part and subsequent rotor dynamic characteristic tests.

[0101] Engine high-pressure rotor assembly: The initial assembly state of the engine high-pressure rotor is consistent with analysis condition 0. Only the adapter shaft 51 is installed at the front shaft diameter 4, and the adjustment shaft 52 structure is not installed. The engine high-pressure rotor is installed on the test bench.

[0102] Test preparation: Measuring points should be arranged on the high-pressure rotor of the engine, typically including the vibration velocities of the front and rear supports. If conditions permit, additional vibration displacement measurements can be taken at multiple points on the outer circumference of the rotor disc. If an elastic support structure is available, strain gauges can also be placed on the elastic supports for strain measurement.

[0103] Experimental Verification: Based on the vibration of the engine's high-pressure rotor, determine whether the rotor's bending critical speed has fallen within the rotor's maximum operating speed range. Near the bending critical speed, the vibration amplitude gradually increases, and the phase undergoes a 180° phase reversal. If it falls within this range, the bending critical speed verification for that adjustment shaft ends; otherwise, proceed to the next adjustment shaft's bending critical speed test. Conduct a frequency sweep test under operating condition 0 to determine if there is a trend of gradually increasing vibration and phase change near the maximum operating speed. Based on the weight of the adjustment shaft 52, install different groups of adjustment shaft 52 structures in ascending order of weight, and conduct frequency sweep tests until the rotor shows a trend of gradually increasing vibration and phase change within the maximum operating speed range under operating condition j. The calculated bending critical speed for operating condition j is Ncj, and the measured bending critical speed is Ntj. The deviation between the calculated and measured critical speed values ​​is Δ = (Ncj - Ntj) / Ntj × 100%. As needed, a heavier adjustment shaft 52 can be replaced to obtain the rotor's critical bending speed under more operating conditions, and the analysis method can be verified based on the measured data under multiple operating conditions. In addition, based on the analysis and experimental verification results, a sensitivity curve between the rotor's critical bending speed and the concentrated mass can be plotted. According to this curve, the rotor mass can be accurately controlled and designed according to the design requirements of the critical bending speed.

[0104] The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes provided in this embodiment has at least the following advantages:

[0105] Based on the bending mode vibration of the engine rotor, an installation interface is designed at the front end of the rotor front shaft diameter 4, where deformation is most sensitive. The critical bending speed of the engine rotor is controlled and adjusted by adjusting the mass of the installed adjustment shaft 52.

[0106] This method allows for the adjustment and experimental verification of the bending critical speed, facilitating the acquisition of the engine's bending critical speed and design margin within a predetermined rotor maximum operating speed range. It also provides a precise shaft quality control scheme tailored to margin requirements. This adjustment method does not require altering the main structure of the engine rotor; only minor design modifications to the rotor's front shaft diameter 4 and the addition of an installation interface are needed, making the structural implementation very simple. Furthermore, during rotor dynamic characteristic verification tests, there is no need for repeated loading, unloading, disassembly, and reassembly. The adjustment shaft 52 can be replaced directly on the test bench, enabling highly efficient verification testing. This method has significant engineering application value, greatly saving design, processing, and labor costs, resulting in excellent experimental economics.

[0107] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes, characterized in that, include: The critical bending speed of the engine rotor is adjusted by regulating the local mass of the deformation-sensitive region of the engine rotor; wherein, the deformation-sensitive region refers to the region with the maximum bending modal deformation.

2. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to claim 1, characterized in that, The step of adjusting the critical bending speed of the engine rotor by adjusting the local mass of the deformation-sensitive area of ​​the engine rotor includes: By analyzing the bending mode of the engine rotor, the deformation-sensitive region of the engine rotor is obtained; A simulation analysis model of the critical speed of the engine rotor was established. By adding adjustment components of different masses to the deformation-sensitive area of ​​the engine rotor, bending critical speed analysis was performed to obtain the bending critical speed and design margin corresponding to different masses. Based on the simulation analysis results of the engine rotor critical speed, engine rotor dynamic characteristic test was conducted to verify the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and to obtain the sensitivity curve of the rotor bending critical speed and the local mass of the deformation sensitive area.

3. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to claim 2, characterized in that, The step of obtaining the deformation-sensitive region of the engine rotor through bending mode analysis includes: Through bending modal analysis of the high-pressure rotor of an aero-engine, the deformation-sensitive region of the high-pressure rotor is found to be the front end of the front shaft diameter.

4. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to claim 3, characterized in that, The adjusting component is fixed to the front end of the front axle diameter via an adapter shaft. The front end of the front axle diameter has multiple locating pin holes along its circumference. The outer circumference of the adapter shaft has multiple locating holes, and the inner circumference of the adapter shaft has multiple threaded holes. The locating holes correspond to the locating pin holes and are fixed by locating pins and then abutted by locking nuts. The locking nuts are threadedly connected to the front end of the front axle diameter. The adjusting component has multiple bolt mounting holes along its circumference. The bolt mounting holes correspond to the threaded holes and are fixed by screws.

5. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to claim 4, characterized in that, The adjusting component is an adjusting shaft; the adjusting shaft includes a first shaft section, one end of which is provided with a connecting flange in the circumferential direction, and the connecting flange is provided with a plurality of bolt mounting holes in the circumferential direction; the axial length of the first shaft section is a variable for different mass adjustments.

6. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to claim 5, characterized in that, The adjustment shaft includes a second shaft segment, the diameter of which is greater than that of the first shaft segment. The second shaft segment is coaxially fixed with the first shaft segment and is located at the end of the first shaft segment away from the connecting flange. The diameter and axial length of the second shaft segment are both variables for different mass adjustments.

7. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to any one of claims 2-6, characterized in that, The steps for establishing a simulation analysis model of the critical speed of the engine rotor, which involves adding adjustment components of different masses to the deformation-sensitive area of ​​the engine rotor and performing bending critical speed analysis to obtain the bending critical speed and design margin corresponding to different masses, include: Establish a critical speed analysis model for the engine rotor; Calculate the critical bending speed Nc0 under the initial working condition 0 and the design margin M0 for the distance from the maximum working speed Nwmax, where M0 = (Nc0 - Nwmax) / Nwmax; Calculate the critical bending speed Ncmin and the minimum design margin Mmin from the maximum working speed Nwmax under the condition of increasing the maximum mass adjustment component, where Mmin=(Ncmin-Nwmax) / Nwmax, and the minimum design margin Mmin≤-10%. Calculate the critical bending speed Nci and the design margin Mi of the distance to the maximum working speed Nwmax under different working conditions by adding different mass adjustment components. Mi = (Nci-Nwmax) / Nwmax; Based on Mmin≤Mi<M0, the critical bending speed and design margin corresponding to different masses are obtained.

8. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to any one of claims 2-6, characterized in that, The steps of conducting engine rotor dynamic characteristic tests based on the simulation analysis results of the engine rotor critical speed, verifying the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and obtaining the sensitivity curve of the rotor bending critical speed and the local mass of the deformation-sensitive region include: The simulation analysis results of the critical speed of the engine rotor were verified by physical verification. A sweep frequency test was carried out under the initial working condition 0 state, and the engine rotor was assembled with adjustment parts of different masses in ascending order, and a sweep frequency test was carried out to obtain the bending critical speed within the maximum working speed range. A sensitivity curve is plotted based on the relationship between the obtained critical bending speed and the local mass of the deformation-sensitive region.

9. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to claim 8, characterized in that, The step of conducting engine rotor dynamic characteristic tests based on the simulation analysis results of the engine rotor critical speed, verifying the bending critical speed and design margin corresponding to different masses obtained from the model analysis, and obtaining the sensitivity curve of the rotor bending critical speed and the local mass of the deformation-sensitive region further includes: The deviation value of the bending critical speed obtained by the actual test of the engine rotor dynamic characteristics is calculated between the bending critical speed obtained by the simulation analysis of the engine rotor critical speed. The design margin is adjusted based on the deviation value.

10. The method for adjusting the critical bending speed of an aero-engine rotor based on modal vibration modes according to claim 9, characterized in that, The initial operating condition 0 state is the state in which no adjustment parts are added to the engine rotor.

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