Method, system and equipment for improving stability of bearing cavity cantilever pipeline of aero-engine and computer readable storage medium

Abstract

The invention relates to an aero-engine bearing cavity cantilever pipeline stability improving method, system and equipment and a computer readable storage medium. The lifting method comprises the steps that S1, the flow and the working rotating speed range of an aero-engine bearing cavity pipeline are obtained, and a pipeline model containing an additional unit is established; s2, obtaining a change curve of the inherent frequency of the pipeline model along with the position of the additional unit, a bifurcation diagram of pipeline vibration and a displacement time history curve; s3, based on the position change curve and the actual state point of the engine, adjusting the position of the additional unit to avoid resonance of the pipeline and the engine; and S4, under external vibration excitation, the position of the additional unit is adjusted to restrain pipeline vibration. The invention provides a method, a system and equipment for improving the stability of an aero-engine bearing cavity cantilever pipeline and a computer readable storage medium. The purposes of adjusting the inherent frequency of the pipeline and suppressing vibration are achieved by changing the position of an additional unit of the pipeline.

Description

Technical Field

[0001] The present invention relates to the technical field of aviation engine bearing cavity pipeline vibration, and in particular to a method, a system, a device and a computer-readable storage medium for improving the stability of a cantilever pipeline in an aviation engine bearing cavity. Background Art

[0002] There are various configurations of pipeline structures in the bearing cavity of aircraft engines. Some of the oil supply pipelines constitute a non-conservative system due to the boundary conditions of a cantilever at one end and a nozzle at the other end. Under the influence of internal flow, the stability of the pipeline will change, and flutter may occur when the internal flow rate is high. At the same time, during the operation of the aircraft engine, the cantilever oil supply pipeline in the bearing cavity may be stimulated by nearby gear shafts, accessories, local resonance, etc., resulting in large vibrations, which may lead to catastrophic consequences in severe cases. For example, in 2010, the explosion of the Qantas A380 engine was caused by a defect in the lubricating oil pipe.

[0003] Although during the design phase of aircraft engines, designers will evaluate the natural frequency of the bearing cavity pipeline and try to avoid nearby known excitation frequencies to avoid resonance. However, the operation of aircraft engines is a dynamic process, and there are many factors affecting vibration that cannot be considered during the design phase. When the aircraft engine is in operation, it is very likely that an unknown excitation source will cause pipeline resonance. And when evaluating the natural frequency of the pipeline during the design phase, usually only the dry mode is considered, which will also bring errors to the stability analysis.

[0004] Therefore, if the cantilever pipeline of the aero-engine bearing cavity can be damped in real time and the stability of the pipeline can be improved to a safe range, it will play an important role in the reliability and safety of the aero-engine. At present, in the field of aero-engines, the vibration reduction measures for pipelines are generally to add clamps to clamp the pipelines. The clamps need to be fixed on the casing, which increases the workload and affects the engine configuration.

[0005] There are many operating states of aircraft engines, including slow-running, standard takeoff, high-temperature takeoff, economic cruise, three red lines, etc. At each state point, the rotor frequency of the aircraft engine varies greatly, and the difference in flow rate in the pipeline will cause the change of the natural frequency of the pipeline. The above-mentioned clamp vibration reduction cannot cope with the changes in the rotor frequency and the natural frequency of the pipeline. The clamp may bring a better vibration reduction effect to the pipeline in a certain state, but it cannot be guaranteed at other state points. Summary of the invention

[0006] In view of the above problems in the prior art, the present invention proposes a method, a system, a device and a computer-readable storage medium for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine, which achieves the purpose of adjusting the natural frequency of the pipeline and suppressing vibration by changing the position of the additional unit of the pipeline.

[0007] Specifically, the present invention proposes a method for improving the stability of a cantilever pipeline in an aircraft engine bearing cavity, comprising the steps of:

[0008] S1, obtaining the flow rate and operating speed range of the bearing cavity pipeline of the aircraft engine, and establishing a pipeline model containing an additional unit, wherein the additional unit is arranged on the pipeline and can move along the length direction of the pipeline to change the mass distribution of the pipeline;

[0009] S2, obtaining a curve of the natural frequency of the pipeline model changing with the position of the additional unit, and a bifurcation diagram and a displacement time history curve of pipeline vibration;

[0010] S3, based on the position change curve and the actual state point of the engine, adjusting the position of the additional unit so that the natural frequency of the pipeline is adjusted to outside the operating speed range to avoid resonance between the pipeline and the engine;

[0011] S4, under external vibration excitation, if the pipeline vibration amplitude is greater than a set amplitude, and the natural frequency of the pipeline cannot be adjusted outside the operating speed range, then based on the bifurcation diagram and the displacement time history curve and the actual state point of the engine, the position of the additional unit is adjusted to suppress the pipeline vibration.

[0012] According to an embodiment of the present invention, in step S3, the natural frequency of the pipeline is adjusted to outside the operating speed range, which means that based on the current pipeline flow and operating speed, the position of the additional unit is moved so that the resonance margin is greater than 15%.

[0013] According to one embodiment of the present invention, the aircraft engine is generally a dual-rotor engine, including high-pressure and low-pressure rotors, and the operating speed ranges of the two are different. The aircraft engine is supported by a rotor formed by five fulcrums, wherein the 1st, 2nd, and 5th fulcrums support the low-pressure rotor, and the 3rd and 4th fulcrums support the high-pressure rotor; if the pipeline is located in the bearing cavity of the 1st, 2nd, and 5th fulcrums, it is easy to be excited by the low-pressure rotor, and if it is located in the bearing cavity of the 3rd and 4th fulcrums, the pipeline is easy to be excited by the high-pressure rotor;

[0014] According to the operating range within the typical flight envelope of the aircraft engine, under the slow-takeoff condition, the corresponding operating speed range of the low-pressure rotor is 800-3500RPM, and the corresponding rotor frequency is 13-58Hz; the corresponding operating speed range of the high-pressure rotor is 12000-18000RPM, and the corresponding rotor frequency is 200-300Hz; within the operating speed range and within plus or minus 15% of the rotor frequency under specific conditions, a pipeline model is established based on the pipeline flow.

[0015] According to one embodiment of the present invention, in step S2, the process of obtaining the curve of the natural frequency of the pipeline model changing with the position of the additional unit comprises the steps of:

[0016] S21, degenerating the dynamic control equation of the pipeline into a linear equation:

[0017]

[0018] Where q = [q1; q2q N ], and are the amplitude, velocity and acceleration corresponding to each modal vibration of the pipeline, M L ,C L ,K L They represent the mass matrix, damping matrix, and stiffness matrix respectively, and the subscript L represents that it is a linear term;

[0019] S22, using the Galerkin method for modal truncation, the partial differential equation is converted into an ordinary differential equation for numerical solution;

[0020] S23, transform the linear control equation into an eigenvalue problem;

[0021] S24, changing the parameters of the additional unit position, reflecting the additional unit position change into the control equation by changing the Dirac delta function, and calculating the natural frequency of the pipeline at different positions of the additional unit.

[0022] According to one embodiment of the present invention, in step S22, the vibration amplitude η(ξ,τ) is expressed as:

[0023]

[0024] Where φj(ξ) is the classical cantilever beam modal function, and qj(τ) is the generalized coordinate corresponding to the discrete system;

[0025] The modal function of the cantilever beam can be expressed as:

[0026]

[0027] σ=(cos(λ i ξ)+cos(λ i ξ)) / (sin(λ i ξ)-sh(λ i ξ));

[0028] M L ,C L ,K L Through Galerkin mode truncation, its dimensionless form can be expressed as:

[0029]

[0030]

[0031]

[0032] Among them, the dimensionless parameter

[0033] According to one embodiment of the present invention, in step S23, the following matrices and vectors are defined:

[0034]

[0035] Then the linear equation can be transformed into:

[0036]

[0037] make λ i =iω i ;

[0038] Then the linear control equation is transformed into the following eigenvalue λ problem:

[0039] (λI-Y)A=0;

[0040] in,

[0041] From the relationship λi=iωi, we can see that the imaginary part of the eigenvalue λ is the vibration frequency, and the real part is the damping.

[0042] According to one embodiment of the present invention, in step S2, the process of obtaining the bifurcation diagram and the displacement time history curve of pipeline vibration includes:

[0043] The nonlinear control equation of the dynamic control equation of the pipeline is obtained:

[0044]

[0045] Based on the dimensionless parameters, the nonlinear control equation is dimensionlessly expressed as:

[0046]

[0047] The nonlinear equation is solved by the Runge-Kutta numerical method.

[0048] The present invention also provides a system for improving the stability of the cantilever pipeline of the bearing cavity of an aircraft engine, which is applicable to the aforementioned improving method, and the improving system comprises:

[0049] An acquisition unit, used to obtain the flow rate and operating speed range of the pipeline of the aircraft engine bearing cavity;

[0050] Establishing units, used to establish pipeline models with additional units based on flow and operating speed range;

[0051] A calculation unit, used to obtain a curve of the natural frequency of the pipeline model changing with the position of the additional unit, and a bifurcation diagram and a displacement time history curve of pipeline vibration;

[0052] The regulating device is used to adjust the position of the additional unit based on the position change curve and the actual state point of the engine so that the natural frequency of the pipeline is adjusted to outside the operating speed range; the regulating device is also used to adjust the position of the additional unit to suppress the pipeline vibration based on the bifurcation diagram, the displacement time history curve and the actual state point of the engine if the pipeline vibration amplitude is greater than a set amplitude and the natural frequency of the pipeline cannot be adjusted to outside the operating speed range under external vibration excitation.

[0053] The present invention also provides a device for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the computer program, the steps of any of the aforementioned methods for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine are implemented.

[0054] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of the method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity as described in any of the above items are implemented.

[0055] The present invention provides a method, system, device and computer-readable storage medium for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine, which achieves the purpose of adjusting the natural frequency of the pipeline and suppressing vibration by changing the position of an additional unit of the pipeline.

[0056] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The accompanying drawings are included to provide further explanation of the present invention, and are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present invention and together with the description serve to explain the principle of the present invention.

[0058] In the attached figure:

[0059] Figure 1 A flowchart of a method for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine according to an embodiment of the present invention is shown.

[0060] Figure 2 A schematic diagram of a pipeline model according to an embodiment of the present invention is shown.

[0061] Figure 3 A schematic diagram showing a curve of the natural frequency of a pipeline model changing with the position of an additional unit according to an embodiment of the present invention.

[0062] Figure 4 A bifurcation diagram of pipeline vibration according to an embodiment of the present invention is shown.

[0063] Figure 5 A schematic diagram showing a displacement time history curve of pipeline vibration according to an embodiment of the present invention is shown.

[0064] Figure 6 A schematic structural diagram of a system for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0065] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0066] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0067] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0068] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0069] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0070] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0071] Figure 1 A flowchart of a method for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine according to an embodiment of the present invention is shown. Figure 2 FIG. 1 is a schematic diagram of a pipeline model according to an embodiment of the present invention. Figure 1 As shown, the present invention provides a method for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine, comprising the steps of:

[0072] S1, obtain the flow rate and operating speed range of the aircraft engine bearing cavity pipeline, and establish a pipeline model with additional units. Figure 2, X represents the axial direction of the cantilever pipe 201, Y represents the lateral direction of the cantilever pipe 201, U represents the flow velocity in the pipe, and the additional unit 202 can be moved along the axial direction of the pipe to change the mass distribution of the pipeline. In the figure, the additional unit 202 is located at the axial position ξj of the pipe.

[0073] The dynamic control equations of the cantilever pipeline with additional units are established based on the extended Hamilton principle. Specifically, the following assumptions need to be made before establishing the theoretical model: (1) the fluid is a steady flow and is incompressible; (2) the cantilever pipeline with slender characteristics is regarded as an Euler-Bernoulli beam model on a two-dimensional plane; (3) the viscoelastic damping of the pipe is ignored; (4) the pipeline axis cannot be extended. Based on the above assumptions, the control equations of the cantilever pipeline can be established by the Hamilton principle:

[0074]

[0075] Among them, T tot is the total kinetic energy of the system, V tot is the total potential energy of the system. The right side of the formula is the virtual work done when the fluid flows out of the free end of the pipe. The total kinetic energy of the system is composed of the kinetic energy of the pipe and the fluid, and the total potential energy is composed of the pipe strain energy and the gravitational potential energy. The additional unit is attached to the mass matrix through the Dirac delta function. Finally, the dynamic control equation is obtained:

[0076]

[0077] Where q = [q1; q2q N …qN], and They are the amplitude, velocity and acceleration corresponding to each modal vibration of the pipeline. L ,M N ,C L ,C N ,K L ,K N Represents mass matrix, damping matrix, and stiffness matrix; the subscript L represents a linear term, and the subscript N represents a nonlinear term.

[0078] S2, obtain the curve of the natural frequency of the pipeline model changing with the position of the additional unit, and the bifurcation diagram and displacement time history curve of the pipeline vibration;

[0079] S3, based on the position change curve and the actual state point of the engine, adjust the position of the additional unit so that the natural frequency of the pipeline is adjusted to outside the operating speed range to avoid resonance between the pipeline and the engine;

[0080] S4, under external vibration excitation, if the pipeline vibration amplitude is greater than a set amplitude, and the natural frequency of the pipeline cannot be adjusted outside the operating speed range, then based on the bifurcation diagram, the displacement time history curve and the actual state point of the engine, the position of the additional unit is adjusted to suppress the pipeline vibration.

[0081] Preferably, in step S3, the natural frequency of the pipeline is adjusted to outside the operating speed range, which means that based on the current pipeline flow and the operating speed, the position of the additional unit is moved so that the resonance margin is greater than 15%.

[0082] Preferably, in this embodiment, the applicable aircraft engine is usually a twin-rotor engine, including high-pressure and low-pressure rotors, and the operating speed ranges of the two are different. The twin-rotor engine is supported by five fulcrums, wherein the 1st, 2nd, and 5th fulcrums support the low-pressure rotor, and the 3rd and 4th fulcrums support the high-pressure rotor; if the pipeline is located in the bearing cavity of the 1st, 2nd, and 5th fulcrums, it is easy to be excited by the low-pressure rotor, and if it is located in the bearing cavity of the 3rd and 4th fulcrums, it is easy to be excited by the high-pressure rotor;

[0083] According to the operating range within the typical flight envelope of the aircraft engine, under the slow-takeoff condition, the corresponding operating speed range of the low-pressure rotor is 800-3500RPM, and the corresponding rotor frequency is 13-58Hz; the corresponding operating speed range of the high-pressure rotor is 12000-18000RPM, and the corresponding rotor frequency is 200-300Hz; within the operating speed range and within plus or minus 15% of the rotor frequency under specific conditions, a pipeline model is established based on the pipeline flow.

[0084] Preferably, in step S2, the process of obtaining the curve of the natural frequency of the pipeline model changing with the position of the additional unit comprises the steps of:

[0085] S21, degenerate the pipeline dynamic control equation into a linear equation. That is, remove the nonlinear term in the dynamic control equation and obtain the linear equation:

[0086]

[0087] Where q=[q1;q2…q N ], and are the amplitude, velocity and acceleration corresponding to each modal vibration of the pipeline, M L ,C L ,K L They represent the mass matrix, damping matrix, and stiffness matrix respectively, and the subscript L represents that it is a linear term.

[0088] S22, using the Galerkin method for modal truncation, the partial differential equation is converted into an ordinary differential equation for numerical solution;

[0089] S23, transform the linear control equation into an eigenvalue problem;

[0090] S24, changing the parameters of the additional unit position, reflecting the additional unit position change into the control equation by changing the Dirac delta function, and calculating the natural frequency of the pipeline at different positions of the additional unit.

[0091] Preferably, in step S22, the vibration amplitude η(ξ,τ) is expressed as:

[0092]

[0093] in is the classic cantilever beam mode function, q j (τ) is the generalized coordinate corresponding to the discrete system;

[0094] The modal function of the cantilever beam can be expressed as:

[0095]

[0096]

[0097] M L ,C L ,K L Through Galerkin mode truncation, its dimensionless form can be expressed as:

[0098]

[0099]

[0100]

[0101] Among them, the dimensionless parameter

[0102] Preferably, in step S23, the following matrices and vectors are defined:

[0103]

[0104] Then the linear equation can be transformed into:

[0105]

[0106] make λ i =iω i ;

[0107] Then the linear control equation is transformed into the following eigenvalue λ problem:

[0108] (λI-Y)A=0;

[0109] in,

[0110] By λ i =iω i From the relationship, we can see that the imaginary part of the eigenvalue λ is the vibration frequency, and the real part of the eigenvalue λ is the damping.

[0111] Preferably, in step S2, the process of obtaining the bifurcation diagram and the displacement time history curve of pipeline vibration includes:

[0112] Obtain the nonlinear control equations of the pipeline's dynamic control equations:

[0113]

[0114] Based on the dimensionless parameters, the nonlinear control equation is expressed dimensionlessly as:

[0115]

[0116] By solving the nonlinear equation using a high-order Runge-Kutta numerical method, we can obtain the displacement time history curve of the pipeline and the bifurcation diagram of the pipeline vibration.

[0117] In step S3, according to the rotor frequency at different state points of the engine, the position of the additional unit on the pipeline is adjusted so that the natural frequency of the pipeline is adjusted to outside the operating speed range. Figure 3 A schematic diagram of the change curve of the natural frequency of the pipeline model of an embodiment of the present invention with the position of the additional unit is shown. As shown in the figure, the horizontal axis represents the relative position of the additional unit on the pipeline, the horizontal axis of 0 represents the additional unit is located at the fixed end of the cantilever pipeline, and the horizontal axis of 1 represents the additional unit is located at the free end of the cantilever pipeline; the vertical axis represents the natural frequency. The figure shows the change curve of the dimensionless internal flow velocity 0-10, and the internal flow velocity is converted to the internal flow velocity of the bearing cavity oil supply pipe flow at each state point of the aircraft engine (covering the engine working condition), and then calibrated with the curve in the figure, and the natural frequency of the pipeline at each state point of the aircraft engine is obtained. The change curve of the position of the additional unit. It is easy to understand that at each internal flow velocity, the change trend of the natural frequency with the position of the additional unit is consistent, and the natural frequency increases with the distance between the additional unit and the fixed end, showing a trend of first decreasing, then increasing, and then decreasing. During the process of the aircraft engine rising, the rotor frequency gradually increases. In order to avoid the resonance caused by the closeness of the natural frequency of the pipeline and the rotor frequency, the additional unit can be transferred to the middle position of the pipeline to reduce the natural frequency of the pipeline. During the downshifting of the aircraft engine, the rotor frequency gradually decreases. The additional unit can be moved to a position close to the free end of the pipeline to increase the natural frequency of the pipeline, thereby effectively avoiding the rotor frequency, thereby achieving real-time frequency modulation of the pipeline and avoiding resonance.

[0118] In step S4, under external vibration excitation, if the pipeline vibration amplitude is greater than a set amplitude and the natural frequency of the pipeline cannot be adjusted outside the operating speed range, the position of the additional unit is adjusted to suppress the pipeline vibration based on the bifurcation diagram, the displacement time history curve and the actual state point of the engine. Figure 4 The bifurcation diagram of pipeline vibration of an embodiment of the present invention is shown. As shown in the figure, the additional unit position is represented by ksy, and when ksy is 0.25, 0.3, 0.5, 0.7 and 0.75, the dimensionless internal flow velocity is from 8 to 15, and the vibration amplitude of the corresponding pipeline. The horizontal axis is the internal flow velocity, and the vertical axis is the vibration amplitude. Figure 5 A schematic diagram of the displacement time history curve of pipeline vibration of an embodiment of the present invention is shown, and the displacement time history curves are given when the internal flow velocity is 15 and ksy is 0.25, 0.3, 0.5, 0.7 and 0.75. Figure 4 , the pipeline vibration mainly exhibits second-order modal flutter behavior. When the additional unit is located at 0.5 of the cantilever pipeline, the critical value of the internal flow velocity is about 12. When the internal flow velocity exceeds 12, the pipeline vibration amplitude gradually increases with the increase of flow velocity. When the additional unit is located at 0.75 of the cantilever pipeline, the critical value of the internal flow velocity is about 11. When the internal flow velocity exceeds 11, the pipeline vibration amplitude gradually increases with the increase of flow velocity. Based on Figure 4 and Figure 5 For example, when an aircraft engine is in a certain state, when the flow rate in its cantilever pipeline reaches a certain critical value, it will cause pipeline flutter with a large amplitude. At this time, by changing the position of the additional unit, the critical flow rate can be increased or the vibration amplitude can be reduced, thereby effectively suppressing the flutter.

[0119] Figure 6 The structural schematic diagram of a system for improving the stability of a cantilever pipeline in an aircraft engine bearing cavity according to an embodiment of the present invention is shown. As shown in the figure, the present invention also provides a system 600 for improving the stability of a cantilever pipeline in an aircraft engine bearing cavity, which is applicable to the aforementioned improving method. The improving system 600 includes:

[0120] An acquisition unit 601 is used to obtain the flow rate and operating speed range of the pipeline of the aircraft engine bearing cavity;

[0121] Establishing unit 602, for establishing a pipeline model including additional units based on flow rate and operating speed range;

[0122] The calculation unit 603 is used to obtain the curve of the natural frequency of the pipeline model changing with the position of the additional unit, and the bifurcation diagram and displacement time history curve of the pipeline vibration;

[0123] The adjusting device 604 is used to adjust the position of the additional unit based on the position change curve and the actual state point of the engine so that the natural frequency of the pipeline is adjusted to outside the operating speed range; the adjusting device is also used to adjust the position of the additional unit to suppress the pipeline vibration based on the bifurcation diagram, the displacement time history curve and the actual state point of the engine if the pipeline vibration amplitude is greater than a set amplitude and the natural frequency of the pipeline cannot be adjusted to outside the operating speed range under external vibration excitation.

[0124] The present invention also provides a device for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of any of the aforementioned methods for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine are implemented.

[0125] The present invention also provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the steps of any of the aforementioned methods for improving the stability of a cantilever pipeline in a bearing cavity of an aircraft engine are implemented.

[0126] Among them, the specific implementation methods and technical effects of the lifting system, lifting equipment, and computer-readable storage medium can all be referred to the embodiments of the method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity provided by the present invention, and will not be repeated here.

[0127] The invention provides a method, system, device and computer-readable storage medium for improving the stability of a cantilever pipeline in an aero-engine bearing cavity, which have the following advantages:

[0128] 1. The cantilever pipeline with additional units is theoretically modeled, the theoretical model is improved, and the Dirac delta function is used to represent the additional units;

[0129] 2. It has good adaptability to various state points of aircraft engines, and can adjust the position of additional units for frequency modulation and vibration reduction according to changes in pipeline flow and rotor frequency at various state points;

[0130] 3. Only the mass matrix of the pipeline is changed, while the damping and stiffness of the pipeline are not affected, and the boundary conditions of the pipeline are not changed, so the evaluation is more convenient.

[0131] Those skilled in the art will further appreciate that the various illustrative logic blocks, modules, circuits, and algorithm steps described in conjunction with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or a combination of the two. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps are generally described above in terms of their functionality. Whether such functionality is implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system. The technician may implement the described functionality in different ways for each specific application, but such implementation decisions should not be interpreted as resulting in a departure from the scope of the present invention.

[0132] The various illustrative logic modules and circuits described in conjunction with the embodiments disclosed herein may be implemented or executed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in cooperation with a DSP core, or any other such configuration.

[0133] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software module may reside in a RAM memory, a flash memory, a ROM memory, an EPROM memory, an EEPROM memory, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative, a storage medium may be integrated into a processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0134] In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented as a computer program product in software, each function may be stored on or transmitted by a computer-readable medium as one or more instructions or codes. Computer-readable media include both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. Storage media may be any available medium that can be accessed by a computer. As an example and not limitation, such a computer-readable medium may include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, disk storage or other magnetic storage device, or any other medium that can be used to carry or store the desired program code in the form of an instruction or data structure and can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwaves, the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwaves are included in the definition of the medium. Disk and disc as used herein include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and Blu-ray disc, wherein disk often reproduces data magnetically, while disc reproduces data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

[0135] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A method for improving the stability of a cantilever pipeline in an aircraft engine bearing cavity, comprising the steps of: S1, obtaining the flow rate and operating speed range of the bearing cavity pipeline of the aircraft engine, and establishing a pipeline model containing an additional unit, wherein the additional unit is arranged on the pipeline and can move along the length direction of the pipeline to change the mass distribution of the pipeline; S2, obtaining a curve of the natural frequency of the pipeline model changing with the position of the additional unit, and a bifurcation diagram and a displacement time history curve of pipeline vibration; S3, based on the position change curve and the actual state point of the engine, adjusting the position of the additional unit so that the natural frequency of the pipeline is adjusted to outside the operating speed range to avoid resonance between the pipeline and the engine; S4, under external vibration excitation, if the pipeline vibration amplitude is greater than a set amplitude, and the natural frequency of the pipeline cannot be adjusted outside the operating speed range, then based on the bifurcation diagram and the displacement time history curve and the actual state point of the engine, the position of the additional unit is adjusted to suppress the pipeline vibration.

2. The method for improving the stability of the pipeline in the bearing cavity of an aircraft engine according to claim 1, characterized in that: In step S3, adjusting the natural frequency of the pipeline to outside the operating speed range means moving the additional unit position to make the resonance margin greater than 15% based on the current pipeline flow and operating speed.

3. The method for improving the stability of the pipeline in the bearing cavity of an aircraft engine according to claim 1, characterized in that: The aircraft engine is usually a dual-rotor engine, including high-pressure and low-pressure rotors, and the operating speed ranges of the two are different. The aircraft engine is supported by a rotor with five fulcrums, wherein the 1st, 2nd, and 5th fulcrums support the low-pressure rotor, and the 3rd and 4th fulcrums support the high-pressure rotor; if the pipeline is located in the bearing cavity of the 1st, 2nd, and 5th fulcrums, it is easy to be excited by the low-pressure rotor, and if it is located in the bearing cavity of the 3rd and 4th fulcrums, it is easy to be excited by the high-pressure rotor; According to the operating range within the typical flight envelope of the aircraft engine, under the slow-takeoff condition, the corresponding operating speed range of the low-pressure rotor is 800-3500RPM, and the corresponding rotor frequency is 13-58Hz; the corresponding operating speed range of the high-pressure rotor is 12000-18000RPM, and the corresponding rotor frequency is 200-300Hz; within the operating speed range and within plus or minus 15% of the rotor frequency under specific conditions, a pipeline model is established based on the pipeline flow.

4. The method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity as claimed in claim 1, characterized in that: In step S2, the process of obtaining the curve of the natural frequency of the pipeline model changing with the position of the additional unit includes the steps of: S21, degenerating the dynamic control equation of the pipeline into a linear equation: Where q=[q1;q2…q N ], and are the amplitude, velocity and acceleration corresponding to each modal vibration of the pipeline, M L ,C L ,K L They represent the mass matrix, damping matrix, and stiffness matrix respectively, and the subscript L represents that it is a linear term; S22, using the Galerkin method for modal truncation, the partial differential equation is converted into an ordinary differential equation for numerical solution; S23, transform the linear control equation into an eigenvalue problem; S24, changing the parameters of the additional unit position, reflecting the additional unit position change into the control equation by changing the Dirac delta function, and calculating the natural frequency of the pipeline at different positions of the additional unit.

5. The method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity as claimed in claim 4, characterized in that: In step S22, the vibration amplitude η(ξ,τ) is expressed as: Where φj(ξ) is the classical cantilever beam modal function, and qj(τ) is the generalized coordinate corresponding to the discrete system; The modal function of the cantilever beam can be expressed as: σ=(cos(λ i ξ)+cos(λ i ξ)) / (sin(λ i ξ)-sh(λ i ξ)); M L ,C L ,K L Through Galerkin mode truncation, its dimensionless form can be expressed as: Among them, the dimensionless parameter 6. The method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity as claimed in claim 4, characterized in that: In step S23, the following matrices and vectors are defined: Then the linear equation can be transformed into: make Then the linear control equation is transformed into the following eigenvalue λ problem: (λI-Y)A=0; in, From the relationship λi=iωi, we can see that the imaginary part of the eigenvalue λ is the vibration frequency, and the real part is the damping.

7. The method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity as claimed in claim 5, characterized in that: In step S2, the process of obtaining the bifurcation diagram and displacement time history curve of pipeline vibration includes: The nonlinear control equation of the dynamic control equation of the pipeline is obtained: Based on the dimensionless parameters, the nonlinear control equation is dimensionlessly expressed as: The nonlinear equation is solved by the Runge-Kutta numerical method.

8. A system for improving the stability of a cantilever pipeline in an aircraft engine bearing cavity, applicable to the method for improving the stability of a cantilever pipeline in an aircraft engine bearing cavity according to claim 1, characterized in that: The lifting system includes: An acquisition unit, used to obtain the flow rate and operating speed range of the pipeline of the aircraft engine bearing cavity; Establishing units, used to establish pipeline models with additional units based on flow and operating speed range; A calculation unit, used to obtain a curve of the natural frequency of the pipeline model changing with the position of the additional unit, and a bifurcation diagram and a displacement time history curve of pipeline vibration; The regulating device is used to adjust the position of the additional unit based on the position change curve and the actual state point of the engine so that the natural frequency of the pipeline is adjusted to outside the operating speed range; the regulating device is also used to adjust the position of the additional unit to suppress the pipeline vibration based on the bifurcation diagram, the displacement time history curve and the actual state point of the engine if the pipeline vibration amplitude is greater than a set amplitude and the natural frequency of the pipeline cannot be adjusted to outside the operating speed range under external vibration excitation.

9. A device for improving the stability of a cantilever pipeline of an aircraft engine bearing cavity, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity as described in any one of claims 1-7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method for improving the stability of the cantilever pipeline of the aircraft engine bearing cavity as described in any one of claims 1 to 7 are implemented.

Images