CN113804425B - Early friction instability fault identification method for sleeve gear connection structure - Google Patents
Early friction instability fault identification method for sleeve gear connection structure Download PDFInfo
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Abstract
The invention provides a method for identifying early friction instability faults of a sleeve gear connecting structure. The critical rotating speed of a rotor system with a sleeved tooth connecting structure is determined, the critical rotating speed of the rotor system can be calculated by using a finite element method, and a characteristic frequency band of early destabilization faults of friction of sleeved teeth is determined. In practice, the first order critical speed of the rotor system can be obtained by experimental methods or calculation methods of commercial software. Collecting vibration signals of a rotor system and collecting rotating speed, further judging whether the rotating speed is slightly higher than first-order critical rotating speed, collecting vibration signals in a characteristic frequency band, calculating a characteristic value of the early instability fault of the sleeve gear friction, and judging whether the early instability fault of the sleeve gear friction occurs according to the characteristic value. The method can effectively avoid the occurrence of major loss caused by instability faults, has simple identification process and small operand, has millisecond-level response time under a mainstream computing platform, is quick in response, can be completely applied to airborne equipment in an expanded way, and has higher engineering application value.
Description
Technical Field
The invention relates to the field of aircraft engine fault diagnosis, in particular to a method for identifying an early-stage instability fault of a sleeve gear connecting Structure (Spline Joint Structure) due to tooth surface friction.
Background
At present, a rotor system of an aero-engine adopts a double-rotor structure, and the span of a low-pressure rotor is long, so that a sleeve tooth connecting structure is adopted for connection. The sleeve gear connecting structure is one of the most common coupling structures in an aircraft engine. The low-pressure rotor is mainly used on a low-pressure rotor of an aircraft engine and used for connecting a turbine shaft and a fan shaft, so that the two shafts synchronously rotate and play roles in transmitting torque and axial force. The structure has the advantages of strong bearing capacity, high centering precision, compact structure, simple structure, convenience in installation, capability of transferring larger torque and axial load and the like. Unlike the splined connections used with ground rotating machines, aircraft engine rotor systems with a splined connection typically operate above a critical rotational speed and therefore risk frictional instability. When the tooth surface of the sleeve tooth connection structure slides, the stability of the rotor system is affected by the friction force of the tooth surface, and once the rotor system is unstable, the result is very serious. In engineering practice, the vibration problem of an aircraft engine caused by instability of a sleeve tooth connecting structure often causes serious consequences. In the test run process of a certain type of engine, due to the friction force generated by the tooth surface friction of the sleeve tooth connecting structure, the cantilever type low-pressure turbine rotor in the supercritical working state generates self-excitation, so that the engine has larger vibration. When the rotor system enters the instability region, the vibration state is difficult to control, and the risk is very high, so that a method needs to be found for identifying the friction early-stage instability fault of the sleeve tooth connecting structure when the rotor system does not enter the complete instability state, and the safety and the reliability of the operation of the aircraft engine are improved.
Most of the existing researches are focused on the research on the design of a sleeve tooth connecting structure, the strength of the sleeve tooth and the rotor dynamic characteristics of the sleeve tooth connecting structure: shichen et al studied the motion characteristics and the fit relationship OF an aeroengine sleeve tooth connection Structure under the condition OF non-centering inclination angle in the context OF 'aeroengine sleeve tooth Structure fit Robustness Optimization design' (Shichen Ying, Liu hong Mi, Zhou Ping. aeroengine sleeve tooth Structure Dynamic Assembly relationship Robustness Optimization design [ J ]. PROPULSION TECHNOLOGY, 2018,39(01):160-168.Robustness Optimization OF Dynamic Assembly Parameters for an Aero-Engine Spline Structure [ J ]. JOURNAL OF PROPULSION TECHNOLOGY), and deducing a calculation formula of the tooth side clearance of the sleeve tooth structure with the misaligned inclination angle and the sleeve tooth connecting structure characteristic quantity related to the tooth side clearance, the shaft diameter sleeve tooth structure of the compressor of a certain type of aeroengine is calculated and analyzed, and on the basis, the randomness of parameters is considered, and the stability optimization design is carried out on the tooth side clearance of the sleeve tooth connecting structure by applying a fruit fly optimization algorithm. Li Jun Hui et al established a computational analysis model OF a Rotor System set tooth Structure by using a contact finite element Method in the 'study OF Rotor System set tooth Structure dynamics Design Method' (Li Jun Hui, Ma Yan hong, Hongjie. Rotor System set tooth Structure dynamics Design Method [ J ]. aircraft engine, 2009,35(04):36-39.Dynamic Design Method OF space Joint Structure for Rotor System [ J ]. JOURNAL OF AEROENGINE), researched the spacing OF positioning surfaces, structural parameters such as the matching tightness and the contact area OF the positioning surfaces and the influence rule OF load on the connection rigidity and the contact state OF the set tooth connection Structure, and proposed a dynamics Design Method OF the set tooth connection Structure on the basis OF the model, which comprises a connection rigidity Design Method and a contact state Design Method. The connection rigidity OF the aeroengine sleeve Gear Coupling is researched in the ' influence OF the sleeve Gear Coupling on the Vibration characteristic OF the aeroengine ' (Liao Zhongkun, Chen, Wanghai fly ' sleeve Gear Coupling on the Vibration characteristic OF the aeroengine [ J ]. Chinese Mechanical Engineering 2015,26(10):1312-1319.Effects OF Gear Coupling on air-engine Vibration on charateristics [ J ]. JOURNAL OF China Mechanical Engineering), a sleeve Gear dynamic meshing force calculation model is deduced, the sleeve Gear meshing force and the meshing rigidity which change along with torque, sleeve Gear misalignment and dynamic relative displacement are analyzed, a three-pivot rotor dynamic model with the sleeve Gear connection structure is established according to the aeroengine sleeve Gear connection structure, the influence OF the sleeve Gear connection structure rigidity on the frequency response characteristic OF a system is analyzed, under the condition that the angle between rotating shafts is not centered, and the influence rule of the connection rigidity of the sleeve teeth on the misalignment response of the system is analyzed. Roger Ku et al, "Dynamic Coefficients of Axial Coefficients in High-Speed Rotating Machinery" (Ku C.P.Roger, Walton J.F., Lund J.W. Dynamic Coefficients of Axial Coefficients coupling in High-Speed Rotating Machinery [ J ]. Journal of Vibration and Acoustics,1994,116 (3)) demonstrated that internal friction between the sets of teeth is the primary cause of rotor uncoordinated precessional destabilization, with destabilization speeds above 1 order threshold but destabilization frequencies approximately equal to 1 order frequency.
The invention with publication number CN110630646A provides a novel sleeve gear connecting structure, which connects two shafts through an elastic die coupling and a torque transmission sleeve gear to realize high-speed torque transmission between the two shafts, the sleeve gear joint adopts an involute tooth form, the inner sleeve gear joint and the outer sleeve gear joint are easy to assemble through reasonable design of a space between the two gears, and the sleeve gear joint is uniform in stress, stable in transmission and small in vibration through requirements of high gear precision and installation precision. The invention with publication number CN204716783U provides a thought for reducing the easy wear of the side face of the sleeve gear, only the sleeve gear device needs to be replaced when the sleeve gear in the sleeve gear shaft is worn, and the whole sleeve gear shaft does not need to be replaced, thus prolonging the service life of the sleeve gear shaft, and reducing the maintenance cost of the sleeve gear shaft.
Wangtong introduces the failure mechanism OF the instability OF the sleeved tooth connection structure in the 'Stability Analysis OF the sleeved tooth Coupling Rotor' (Wangtong, Wangliang, Liang Ming, Ling. sleeved tooth Coupling Rotor Stability Analysis [ J ]. AEROENGINE, 2021,47(03):66-71.Stability Analysis OF Rotor with spring Coupling [ J ] JOURNAL OF AEROENGINE) and explains the vibration response OF the sleeved tooth Rotor under the action OF internal damping c, it is theorized that the friction force of the tooth surfaces of the sleeve teeth can bring anti-symmetric cross rigidity to the rotor, the anti-symmetric cross rigidity can cause the rotor to be unstable, and proposes that the rotor with the sleeved tooth connecting structure has an intermediate state of transition from a stable state to a serious instability state due to instability caused by sleeved tooth friction, which is called as an early friction instability state, however, no further research has been conducted on how to monitor the early friction instability of a splined rotor. As shown in fig. 1, when the rotor is in an early friction instability state, the sleeve tooth structure has failed, but the vibration amplitude of the rotor does not generate a sudden increase like a serious instability state, and is easily confused with a stable state. If the early friction instability is not cleared in time, serious instability can develop along with the increase of the rotating speed, and the safety of the operation of the engine is seriously damaged. Therefore, the rotor with the sleeved tooth connecting structure is monitored for early friction instability faults, and the rotor is stopped in time in the early friction instability state, so that the condition of the engine is prevented from further developing into serious instability, the damage of the instability faults to the engine can be effectively reduced, the fault condition is timely checked and timely replaced and maintained, and the safe and reliable operation of equipment can be further ensured. How to identify early-stage instability faults needs to specially provide a corresponding method and a corresponding flow, but related patent researches are not developed to deeply analyze the early-stage instability faults.
Disclosure of Invention
In order to overcome the defect that a simple and effective sleeve gear connecting structure is lacked in the prior art, the invention provides a method for identifying an early friction instability fault of a rotor with sleeve gears of an aeroengine.
The specific process of the method for identifying the early instability fault of the sleeve gear connecting structure provided by the invention is as follows:
step 1: determining the critical rotating speed of a rotor system with a sleeve gear connecting structure:
it can be seen from the previous study that the rotating speed of the early destabilizing fault of the sleeve tooth connecting structure is above the first-order critical rotating speed, and the frequency of the destabilizing vibration is equal to the frequency of the first-order critical rotating speed. It is therefore desirable to determine a first order critical speed of the rotor system with a cogged connection.
There are many methods for determining the critical rotational speed of the rotor with the cogged connection, such as experimentally, by finite element method calculations or by commercial software. In the present application, a finite element method is taken as an example for calculation.
The process of simplifying the determined rotor system structure with the sleeved tooth connecting structure into a finite element model comprises the following steps: the low-pressure shaft is simplified into the combination of a plurality of low-pressure shaft beam units, the high-pressure shaft is simplified into the combination of a plurality of high-pressure shaft beam units, the low-pressure fan is simplified into a flexible low-pressure fan disc unit, the low-pressure turbine is simplified into a rigid low-pressure turbine disc unit, the front roller bearing of the fan is simplified into a front roller bearing unit of the fan, and the rear roller bearing of the low-pressure turbine is simplified into a rear bearing unit of the low-pressure turbine. The high-pressure compressor is simplified into a rigid high-pressure compressor disc unit, the high-pressure turbine is simplified into a rigid high-pressure turbine disc unit, the high-pressure compressor front roller bearing is simplified into a high-pressure compressor front roller bearing unit, and the intermediate rolling bearing is simplified into an intermediate rolling bearing unit. The sleeve tooth connecting structure is simplified into a sleeve tooth connecting unit. The casing is simplified into a no-mass casing unit.
The finite element model parameters include: elastic modulus, shear modulus, material density, high-pressure shaft beam unit diameter, low-pressure shaft beam unit inner diameter, low-pressure shaft beam unit outer diameter, damping, flexible low-pressure fan disk unit mass, rigid high-pressure compressor disk unit mass, rigid high-pressure turbine disk unit mass, rigid low-pressure turbine disk unit mass, flexible low-pressure fan disk unit moment of inertia, rigid high-pressure compressor disk unit moment of inertia, rigid high-pressure turbine disk unit moment of inertia, rigid low-pressure turbine disk unit moment of inertia, sleeve tooth connection structure unit stiffness, sleeve tooth connection structure unit damping, clearance minimum, intermediate rolling bearing unit position, flexible fan low-pressure disk unit position, low-pressure turbine disk unit position, fan front roller bearing unit position, low-pressure turbine rear bearing unit position, high-pressure compressor front roller bearing unit position, high-pressure turbine rear roller bearing unit position, and gap minimum, The disc unit position of the rigid high-pressure compressor, the disc unit position of the rigid high-pressure turbine and the sleeve tooth connecting structure unit position.
After the finite element model and the parameters of each finite element model are determined, a finite element calculation program is compiled by utilizing a rotor dynamics finite element method to calculate the model, and the critical rotating speed n of the rotor system with the sleeved tooth connecting structure is obtainedcr。
when instability occurs, the sleeve gear connecting structure is abraded to a certain extent, so that the first-order critical rotating speed is reduced compared with the design value, and the characteristic frequency band of the early friction instability fault of the sleeve gear connecting structure is defined to be slightly lower than the first-order critical rotating speed ncrAnd the reduction amplitude of the first-order critical rotating speed of the abraded rotor is within 5 percent, so the instability fault characteristic is as follows:
[0.95ncr,ncr] (1)
step 3, acquiring vibration data of the rotor system with the sleeved tooth connecting structure:
and acquiring vibration data in the acceleration process for the determined rotor system with the sleeved tooth connecting structure. The vibration data and the rotation speed of each moment are recorded.
Because the geared rotor system is unstableThe instability threshold speed is above a first order critical speed, and early instability is taken as an early phenomenon of failure and needs to be detected in advance. If the measurement is carried out in the whole process, the calculated amount is large, so 0.9n is selectedcrThis can reduce the amount of calculation as an index. If the current rotating speed is more than or equal to 0.9ncrThen the subsequent flow steps are carried out, if the current rotating speed is less than 0.9ncrAnd continuing to pull up the rotating speed and continuously acquiring the vibration data of the rotor system.
Step 4, collecting a characteristic frequency band vibration signal of the sleeve gear friction early instability fault:
in step 3, it is determined that the current rotational speed is greater than 0.9ncrAnd then, acquiring and recording the data obtained in the step 3, dividing the acquired data per second, selecting vibration signals of a plurality of periods (such as 16 periods) before each second to perform fast Fourier transform to obtain frequency domain components of the vibration signals, and identifying signals of the characteristic frequency band of the early instability fault of the friction of the set teeth for subsequent judgment processes.
defining the characteristic value S of the sleeve gear friction early instability faultc：
In the above equation omega is the rotation speed at the present moment,
representing the root mean square value of the amplitude of all frequency component vibration signals in the characteristic frequency band of the sleeve tooth friction early instability fault, E[0.95Ω,1.05Ω]Represents [ 0.95. omega., 1.05. omega. ]]The rms amplitude of the vibration signal of all frequency components in this frequency band.
Step 6, judging whether a sleeve gear friction early-stage instability fault occurs according to the characteristic value:
by counting the experimental result of the early-stage instability fault of the friction of the sleeve gear, and according to the experimental result and engineering experience, the critical thrust of the characteristic value of the early-stage instability fault of the friction of the sleeve gear is definedAnd 5, taking 0.25, and comparing the fault characteristic value obtained by calculation in the step 5 with the value of 0.25 to judge whether the early-stage instability fault of the sleeve gear friction occurs. If calculated ScAnd if the value is less than 0.25, the early instability fault of the sleeve gear friction does not occur at the moment, the step 3 is returned, and the rotating speed can be continuously increased and the vibration data of the rotor system can be continuously acquired at the moment. If calculated ScIf the friction coefficient is more than or equal to 0.25, the early instability fault of the sleeve gear friction occurs at the moment, an alarm needs to be sent out, the rotating subsystem needs to be pulled down, and the abrasion conditions of the tooth surface and the positioning surface of the sleeve gear need to be checked.
Thus, the identification of the early destabilization fault of the sleeve tooth friction is completed.
Fig. 3 shows a schematic flow chart of the present invention.
The method can simply and effectively identify the early-stage instability fault of the friction of the sleeve gear. The method makes up the deficiency of the existing research on the identification of the early-stage instability fault of the sleeve gear friction, provides the characteristic energy frequency band of the early-stage instability fault of the sleeve gear friction, provides the identification characteristic quantity and the identification criterion of the early-stage instability fault, and provides the identification process of the early-stage instability fault of the sleeve gear friction.
The method firstly determines the critical rotating speed of the rotor system with the sleeve tooth connecting structure, can calculate the critical rotating speed of the rotor system by utilizing a finite element method, and determines the characteristic frequency band of the sleeve tooth friction early-stage instability fault. In practice, the first order critical speed of the rotor system can be obtained by experimental methods or calculation methods of commercial software. Collecting vibration signals of a rotor system and collecting rotating speed, further judging whether the rotating speed is slightly higher than first-order critical rotating speed, collecting vibration signals in a characteristic frequency band, calculating a characteristic value of the early instability fault of the sleeve gear friction, and judging whether the early instability fault of the sleeve gear friction occurs according to the characteristic value.
Advantageous effects
The invention focuses on early failure before serious instability failure occurs and early warning is carried out, and the device is alarmed and pulled down before the early instability is converted into serious instability, so that the occurrence of serious loss caused by instability failure can be effectively avoided. Meanwhile, the early-stage instability fault identification process provided by the invention is simple, the operand is small, the response time is in millisecond level under the current mainstream computing platform, the response is rapid, the application to airborne equipment can be completely expanded, and the engineering application value is higher.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a vibration frequency spectrum diagram of an early friction instability fault of a rotor with a sleeved tooth connecting structure;
FIG. 2 is a data processing result of an early buckling test of a sleeve gear friction;
FIG. 3 is a schematic flow chart of the present invention;
FIG. 4 is a schematic diagram of a finite element node partition of the experimental design in the embodiment.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.
The embodiment is a fault identification method for identifying early instability of friction of a rotor sleeve gear with a sleeve gear of a certain type of aeroengine, and the specific process is as follows:
the method comprises the following steps: determining the initial structural characteristics of the rotor system with the sleeve gear connecting structure:
in this embodiment, for a small single-disk cantilever rotor tester with a sleeved tooth connection structure, which is designed to have geometric similarity and dynamics similarity to a power turbine shaft of a certain turboshaft engine, the initial structural characteristics of the rotor system with the sleeved tooth connection structure to be determined mainly refer to rotor structural parameters, sleeved tooth connection structural parameters and other parameters.
The rotor structure parameters comprise the length, the radius, the density, the elastic modulus and the Poisson ratio of each shaft section, and the mass, the axis rotary inertia and the diameter rotary inertia of the cantilever disc; the determination processes are respectively as follows:
the length and the radius of each shaft section are determined by an engineering drawing of a small single-disk cantilever rotor experimental device with a sleeved tooth connecting structure, and the density, the elastic modulus and the Poisson ratio of each shaft section are determined by referring to a metal material handbook.
In this embodiment, the initial design parameters of the small single-disk cantilever rotor tester with the set tooth connection structure are shown in table 1. FIG. 4 is a schematic diagram of node division of the experimental device of the present design.
TABLE 1 shaft section design parameters of small single-disk cantilever rotor experimental device with set tooth connection structure
The mass, the axis rotary inertia and the diameter rotary inertia of the cantilever disc are determined by calculation, and the method comprises the following specific steps of:
according to the design drawing of the cantilever disc, the geometrical dimensions of the disc are determined, including the radius R of the disc, the thickness h of the disc and the material of the cantilever disc.
The density ρ of the cantilever disk is determined by referring to the handbook of metallic materials.
The mass m of the cantilever disk is obtained by equation (3). Obtaining the axis rotary inertia I of the cantilever disc by the formula (4)p. Obtaining the diameter moment of inertia I of the cantilever disc by the formula (5)d。
m＝ρπR2h (3)
Wherein R is the radius of the cantilever disk and h is the thickness of the cantilever disk.
The mass, axial moment of inertia, and diametric moment of inertia of the cantilever disk obtained in this example are shown in table 2.
TABLE 2 cantilever disk parameters of small single-disk cantilever rotor tester with set tooth connection structure
Design parameters of the set tooth structure used in the embodiment are determined by engineering drawings of a small single-disk cantilever rotor experimental device with a set tooth connecting structure and set tooth parameters. Other parameters of the rotor system with the sleeve gear connecting structure refer to the working rotating speed range of the rotor system. And selecting the working rotating speed range of the engine rotor system by consulting the aviation engine design manual.
The working rotating speed range of the rotor system determined in the embodiment is omega epsilon (0r/min, 5500 r/min).
Step 1, calculating the critical rotating speed of a rotor system with a sleeve gear connecting structure:
according to the determined rotor structure parameters of the rotor system with the sleeved tooth connecting structure, the system structure is simplified into a finite element model.
In this embodiment, the process of simplifying the determined rotor system structure with the set tooth connection structure into a finite element model is as follows: the rotor shaft is simplified into a rotor shaft beam unit, the cantilever disc is simplified into a rigid cantilever disc unit, the power turbine rear roller bearing is simplified into a power turbine rear roller bearing unit, and the sleeve tooth connecting structure is simplified into a sleeve tooth unit. The finite element model parameters are given by the structural parameters determined in step 1.
After the finite element model and the parameters of each finite element model are determined, a finite element calculation program is programmed by using a rotor dynamics finite element method to calculate the model, and the critical rotating speeds of each order of the rotor system with the sleeved tooth connecting structure in the embodiment are obtained and are shown in table 3.
TABLE 3 Critical speed distribution
the characteristic frequency band of the sleeve tooth friction early instability fault defined by the formula (1) is [0.95ncr,ncr]In the formula ncrIs the first order critical speed of the rotor system. According to the critical rotating speed determined in the step 2, the characteristic frequency band of the early instability fault of the friction of the sleeve gear in the embodiment can be determined to be [1886.7r/min,1986r/min ]]I.e., [31.4Hz, 33.1Hz]。
Step 3, collecting a rotor system vibration data sample with the sleeve tooth connecting structure:
in this embodiment, the rotor system is flexibly connected with the motor through the flange plate, and the frequency converter controls the rotation speed of the motor to drive the rotor system. In the experimental process, two vibration displacement sensors are used for acquiring vibration signals of the horizontal direction and the vertical direction of the cantilever disc, and one photoelectric sensor is used for acquiring the real-time rotating speed of the rotor system. And controlling the frequency converter to accelerate the rotor system from 300Rpm continuously, acquiring vibration data in the acceleration process, and recording a vibration signal and a rotating speed signal at each moment.
The existing research shows that the instability threshold rotating speed of the instability of the rotor system with the sleeved teeth is at the first-order critical rotating speed ncrIn order to monitor early buckling failure, 0.9n is definedcrIs a judgment index. In the experimental process of the embodiment, the collected rotating speed signal of the rotor system is judged in real time, and if the current rotating speed is greater than 0.9ncrThen the subsequent flow steps are carried out, if the current rotating speed is less than 0.9ncrAnd continuing to pull up the rotating speed and continuously acquiring the vibration data of the rotor system.
Step 4, collecting a characteristic frequency band vibration signal of the sleeve gear friction early instability fault:
in the present embodiment, the current rotation speed reaches a defined 0.9ncrThen, acquiring and recording signals [31.4Hz, 33.1Hz ] in the characteristic frequency band of the sleeve tooth friction early instability fault determined in the step 2]Used in the subsequent judgment process.
defining the characteristic value S of the sleeve gear friction early instability faultcAnd is and
where omega is the rotational speed at the present moment,
representing the root mean square value of the amplitude of all frequency component vibration signals in the characteristic frequency band of the sleeve tooth friction early instability fault, E[0.95Ω,1.05Ω]Represents [ 0.95. omega., 1.05. omega. ]]The rms amplitude of the vibration signal of all frequency components in this frequency band.
Step 6, judging whether a sleeve gear friction early-stage instability fault occurs according to the characteristic value:
and (5) defining the critical value of the characteristic value of the early-stage instability fault of the sleeve gear friction to be 0.25, and comparing the value of the characteristic value of the fault calculated in the step (5) with the value of 0.25 to judge whether the early-stage instability fault of the sleeve gear friction occurs. If calculated ScAnd if the value is less than 0.25, the early instability fault of the sleeve gear friction does not occur at the moment, the step 4 is returned, and the rotating speed can be continuously increased and the vibration data of the rotor system can be continuously acquired at the moment. If calculated ScIf the friction coefficient is more than 0.25, the early instability fault of the sleeve gear friction occurs at the moment, an alarm needs to be sent out, the rotating subsystem needs to be pulled down, and the abrasion conditions of the tooth surface and the positioning surface of the sleeve gear need to be checked.
According to the statistical experiment result, the unstable frequency band range is determined to be [0.95n ]cr,ncr]And determining that the instability fault characteristic value critical is 0.25. The statistics of the experimental results are as follows:
| numbering | Frequency of instability | Ratio of destabilization frequency to critical rotation speed | Characteristic value of instability fault |
| 1 | 32.8Hz | 98.8％ | 2.06 |
| 2 | 31.6Hz | 95.2％ | 0.46 |
| 3 | 32.2Hz | 97.6％ | 1.88 |
| 4 | 31.9Hz | 96.1％ | 0.36 |
The data processing results of the early instability test of the sleeve gear friction are shown in the attached figure 2.
In this embodiment, the rotor system continuously increases the rotation speed, and calculates the fault characteristic value at the current moment in real time. When the rotating speed of the rotor system is pulled up to 4043r/min, the calculated fault characteristic S is foundc0.46 or more and 0.25 or less, and early stage of gear tooth friction is judged to have occurredAnd (4) giving an alarm and timely pulling and stopping the rotor system when the instability fault occurs, and checking the abrasion condition of the sleeve gear connecting structure after pulling and stopping. After the detection, the fault characteristics which accord with the early-stage instability are found, which shows that the method can effectively detect and judge the early-stage instability fault of the friction of the sleeve gear and can avoid the harm caused by the transformation from the early-stage instability to the serious instability.
Therefore, the whole process of the method for identifying the early instability fault of the sleeve gear friction is completed.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.
Claims (7)
1. A method for identifying early friction instability faults of a sleeve gear connecting structure is characterized by comprising the following steps: the method comprises the following steps:
step 1: determining the critical speed n of a rotor system having a toothed connectioncr；
Step 2: determining a characteristic frequency band [0.95n ] of early friction instability fault of a sleeve gear connecting structurecr,ncr]；
And step 3: collecting vibration data of the rotor system with the sleeve gear connecting structure, performing subsequent flow steps when the rotating speed of the rotor system is greater than or equal to a set rotating speed, and otherwise, continuously collecting the vibration data of the rotor system;
and 4, step 4: processing the rotor system vibration data acquired in the step 3 after the rotating speed of the rotor system is greater than or equal to the set rotating speed to obtain frequency domain components of the vibration data;
and 5: according to the frequency domain components of the vibration data obtained in the step 4, using a formula
Calculating the early destabilization of the friction of the gear sleeveBarrier characteristic value ScWhere Ω is the rotor system speed at that moment,
representing the root mean square value E of the amplitude values of all vibration data in the characteristic frequency band of the sleeve tooth friction early-stage instability fault in the frequency domain components of the vibration data obtained in the step 4[0.95Ω,1.05Ω]The frequency domain components representing the vibration data obtained in step 4 are [0.95 Ω,1.05 Ω ]]The magnitude rms values of all vibration data in the frequency band;
step 6, judging whether sleeve gear friction early-stage instability fault occurs according to the characteristic value obtained in the step 5: if calculated ScIf the value is less than 0.25, judging that no sleeve gear friction early-stage instability fault occurs at the moment, returning to the step 3, and continuously acquiring the vibration data of the rotor system; if calculated ScAnd if the value is more than or equal to 0.25, judging that the early-stage instability fault of the sleeve tooth friction occurs at the moment.
2. The method for identifying the early friction instability fault of the sleeve gear connecting structure according to the claim 1, is characterized in that: in the step 1, a finite element method is adopted to calculate the critical rotating speed of the rotor system with the sleeve tooth connecting structure.
3. The method for identifying the early friction instability fault of the sleeve gear connecting structure according to the claim 2, is characterized in that: when the finite element method is adopted for calculation in the step 1, the process of simplifying the rotor system with the sleeved tooth connecting structure into a finite element model is as follows: the low-pressure shaft is simplified into the combination of a plurality of low-pressure shaft beam units, the high-pressure shaft is simplified into the combination of a plurality of high-pressure shaft beam units, the low-pressure fan is simplified into a flexible low-pressure fan disc unit, the low-pressure turbine is simplified into a rigid low-pressure turbine disc unit, the front roller bearing of the fan is simplified into a front roller bearing unit of the fan, the rear roller bearing of the low-pressure turbine is simplified into a rear bearing unit of the low-pressure turbine, the high-pressure compressor is simplified into a rigid high-pressure compressor disc unit, the high-pressure turbine is simplified into a rigid high-pressure turbine disc unit, the front roller bearing of the high-pressure compressor is simplified into a front roller bearing unit of the high-pressure compressor, the intermediate rolling bearing is simplified into an intermediate rolling bearing unit, the sleeve tooth connecting structure is simplified into a sleeve tooth connecting unit, and the casing is simplified into a no-mass casing unit.
4. The method for identifying the early friction instability fault of the sleeve gear connecting structure according to the claim 2, is characterized in that: in step 1, when the finite element method is adopted for calculation, parameters of the finite element model comprise: elastic modulus, shear modulus, material density, high-pressure shaft beam unit diameter, low-pressure shaft beam unit inner diameter, low-pressure shaft beam unit outer diameter, damping, flexible low-pressure fan disk unit mass, rigid high-pressure compressor disk unit mass, rigid high-pressure turbine disk unit mass, rigid low-pressure turbine disk unit mass, flexible low-pressure fan disk unit moment of inertia, rigid high-pressure compressor disk unit moment of inertia, rigid high-pressure turbine disk unit moment of inertia, rigid low-pressure turbine disk unit moment of inertia, sleeve tooth connection structure unit stiffness, sleeve tooth connection structure unit damping, clearance minimum, intermediate rolling bearing unit position, flexible fan low-pressure disk unit position, low-pressure turbine disk unit position, fan front roller bearing unit position, low-pressure turbine rear bearing unit position, high-pressure compressor front roller bearing unit position, high-pressure turbine rear roller bearing unit position, and gap minimum, The disc unit position of the rigid high-pressure compressor, the disc unit position of the rigid high-pressure turbine and the sleeve tooth connecting structure unit position.
5. The method for identifying the early friction instability fault of the sleeve gear connecting structure according to the claim 1, is characterized in that: in step 3, the set rotation speed is 0.9ncr。
6. The method for identifying the early friction instability fault of the sleeve gear connecting structure according to the claim 1, is characterized in that: and 4, dividing the vibration data of the rotor system acquired in the step 3 after the rotating speed of the rotor system is greater than or equal to the set rotating speed according to each second, and selecting the vibration data of a plurality of periods before each second to perform fast Fourier transform to obtain frequency domain components of the vibration data.
7. The method for identifying the early friction instability fault of the sleeve gear connecting structure according to the claim 6, is characterized in that: and 4, selecting vibration data of 16 periods before each second to perform fast Fourier change.
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| CN107036816A (en) * | 2016-11-17 | 2017-08-11 | 重庆工商大学 | A kind of Aero-engine Bearing method for diagnosing faults |
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| CN109934206A (en) * | 2019-04-08 | 2019-06-25 | 中国矿业大学(北京) | A kind of rotary machinery fault diagnosis method under non-stationary operating condition |
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