Method for identifying vibration steady-state working condition of aero-engine

Abstract

The invention relates to the technical field of aero-engines, and discloses an aero-engine vibration steady-state working condition identification method, which is used for judging whether the state of an engine is a steady state or not based on the change rule of the rotating speed, and dividing the working conditions according to the average rotating speed of the steady state and the rotating speed change rule between the working conditions. According to the method, the problems of misjudgment, repeated transverse jumping of the state and the like in the prior art are solved.

Description

Technical Field

[0001] The invention relates to the technical field of aeroengines, and in particular to a method for identifying a vibration steady-state condition of an aeroengine. Background Art

[0002] As the structure of aircraft engines becomes increasingly complex and their performance continues to improve, their vibration faults are becoming more diverse and more serious, which directly leads to reduced engine reliability. Therefore, carrying out aircraft engine fault diagnosis is one of the important measures to ensure the normal operation of aircraft engines and improve the equipment availability rate. The study of data information mining methods is an important direction of current engine fault diagnosis and prediction research. The historical engine test vibration data contains a lot of useful information. In-depth mining of this data information will help to understand the status of the engine. Studying the differences between historical data and current test data will help improve the accuracy of fault diagnosis and prediction.

[0003] The study found that the engine vibration state has obvious differences in the steady-state and transitional states, and the vibration state does not belong to the same distribution under different speed conditions. Moreover, for the same speed, the vibration conditions under the operating condition will also be different when increasing from a low speed to the speed condition and when decreasing from a high speed to the speed condition. Figure 1 Indicates these two speed-up and speed-down states. Figure 1 The + and - are marked in the figure, which are referred to as the speed increase condition and the speed decrease condition respectively. Therefore, after the massive data is identified and the stable conditions are divided, data information can be effectively extracted and mined.

[0004] Since the vibration of rotating machinery is closely related to the speed of the rotor, the speed value and its stability should be used as the basis for the division of working conditions. However, the engine operating conditions are complex and changeable, and the speed changes are less regular. It is very time-consuming to manually divide the working conditions and judge the status based on massive data. At present, thresholds are often set for the speed difference, speed mean, variance, etc. within the sliding window time period as conditions for determining steady state. However, in some more extreme cases, misjudgment and repeated state jumps may still occur, and the speed working conditions are not divided into speed increase and decrease states.

[0005] The speed change curves of some difficult to judge situations are as follows: Figures 2 to 4 shown.

[0006] like Figure 2 , Figure 3 As shown, it is easy to judge stable at the speed fluctuation point, but it is judged as unstable immediately afterwards, and it is not easy to distinguish between rising and falling conditions.

[0007] like Figure 4As shown in the figure, sometimes there is a small range of speed jump, near the threshold, it only affects a moment, there is a larger and more continuous speed change and variance value. When the threshold is set to a small value, the state is prone to repeated jumps, and when the threshold is set to a large value, it is difficult to identify other types of transition states. Summary of the invention

[0008] In order to overcome the deficiencies of the prior art, the present invention provides a method for identifying the steady-state vibration condition of an aircraft engine, which solves the problems of misjudgment, repeated state jumps, etc. in the prior art.

[0009] The technical solution adopted by the present invention to solve the above problems is:

[0010] A method for identifying steady-state vibration conditions of an aircraft engine determines whether the engine state is steady based on the law of speed change, and divides the working conditions according to the average speed of the steady state and the law of speed change between working conditions.

[0011] As a preferred technical solution, the following steps are included:

[0012] A1, defines the starting speed value and speed increase and decrease status of a flight;

[0013] A2, reads the speed data and stores it in a sliding window with a length of Δt;

[0014] A3, calculate dn and n in the sliding window pp The value of; where dn represents the speed change value, n pp Indicates the speed change amplitude;

[0015] A4, perform steady-state judgment on the data in the sliding window, and use the steady-state judgment result as the current state; if the steady-state judgment result is steady-state, enter step A51X, and then enter step A5; if the steady-state judgment result is transitional state, enter step A51Y, and then enter step A5; wherein A51X is: update the stable segment information, and A51Y is: record the average speed of the stable segment as the reference speed of the transition segment;

[0016] A5, determine whether the flight is ended: if so, end the flight; if not, return to step A2.

[0017] As a preferred technical solution, in step A4, if the previous moment is a transition state, the condition for judging stability is:

[0018] If dn<δn, and n pp <δn / 2, and the speed remains steady for a set period of time T, it is considered that the speed has entered the steady state stage;

[0019] Among them, δn represents the stability threshold, and T represents the time interval of vibration analysis.

[0020] As a preferred technical solution, in step A4, if the previous moment is a steady state, the condition for judging stability is:

[0021] If dn<δn*c, and within a set period of time T, it continues to enter the transition state for T / 4 time, it is considered to have entered the transition state;

[0022] Among them, δn represents the stability threshold, c represents the amplification factor, and T represents the time interval of vibration analysis.

[0023] As a preferred technical solution, in step A4, when making a steady-state judgment, all steady-state conditions in which the high-pressure rotor speed is lower than a set threshold or the stable duration is less than a set time are eliminated.

[0024] As a preferred technical solution, step A51X includes the following steps:

[0025] A51X1, calculate the speed characteristics of the stable stage: take the speed average n of the current steady-state condition as the speed average within T time;

[0026] A51X2, determine whether the current stable segment is in an ascending or descending state;

[0027] A51X3, updates the start and end time, speed average, rising state or falling state information of the stable segment.

[0028] As a preferred technical solution, in step A51X3, the calculation formula for updating the speed mean is:

[0029]

[0030] in, is the average speed, n is the speed value of the last point in the sliding window, and N is the accumulated speed points of the current working condition.

[0031] As a preferred technical solution, in A51X2, the rule for judging whether the current stable segment is in an ascending state or a descending state is as follows: compare the average speed of the current steady-state condition with the reference speed of the transition state. If |current average speed - reference speed|>set threshold, the difference is positive, then it is in an ascending state, and the difference is negative, then it is in a descending state; otherwise, it is considered to be the same state, which is consistent with the state of the previous condition; wherein, || represents absolute value operation.

[0032] As a preferred technical solution, the value of Δt is 1s.

[0033] As a preferred technical solution, the value of T is 0.3-0.5s.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) The present invention is compatible with burrs, steps, and situations where the speed increases first and then decreases;

[0036] (2) The present invention determines stability in a timely manner, avoids repeated jumps between the steady state and the transition state, and distinguishes between the rising and falling states, thereby meeting the statistical requirements for engine vibration data. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the speed increase and decrease state;

[0038] Figure 2 It is one of the speed change curves;

[0039] Figure 3 This is the second speed change curve diagram;

[0040] Figure 4 This is the third speed change curve diagram;

[0041] Figure 5 A schematic diagram of the working condition identification using the present invention;

[0042] Figure 6 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0044] Example 1

[0045] like Figures 1 to 6 As shown in FIG. 1 , in view of the problems of the prior art, a steady-state judgment and working condition division method is proposed based on the speed automatic division of the rising state steady-state working condition and the falling state steady-state working condition. The main process is as follows Figure 6 shown.

[0046] The sliding window method is used to slide the high-pressure rotor relative physical speed data and the low-pressure rotor relative physical speed data from the first point to the last point, and the length of the sliding window is Δt. This method calculates the difference dn between the first and last speed points in the sliding window, the difference n between the maximum and minimum speed values ​​in the sliding window, and the difference dn between the first and last speed points in the sliding window. pp A threshold is set to determine whether the speed is stable. The average value of the high-pressure rotor relative to the physical speed in the steady-state speed section is used as the basis for the working condition division. The method first determines whether the engine state is steady according to the stability judgment rule, and then divides the working condition and the speed increase and decrease state according to the average speed of the steady state and the speed change law between working conditions.

[0047] To judge whether the speed is stable, the threshold is set according to whether it is in a steady state at the previous moment. The initial state is set by the user, usually in a transition state.

[0048] ① If the previous moment is a transition state, the condition for judging stability is:

[0049] dn<δn, and n pp <δn / 2, where δn is the stability threshold;

[0050] And if the steady state is maintained continuously for a period of time T (the time interval of vibration analysis), it is considered that the speed enters the steady-state stage.

[0051] ② The previous moment is a steady state, and the conditions for judging stability are:

[0052] dn<δn*c, where c is the amplification factor.

[0053] And if it continues to enter the transition state for T / 4 time within a period of time T, it is considered to have entered the transition state.

[0054] In this way, the requirements are appropriately relaxed in steady state, making it difficult to judge it as a transition state, and accommodating the occasional speed step situation; in transition state, a threshold for the speed difference in the sliding window is added, and the speed fluctuation before entering the steady state is strictly judged to be stable to prevent misjudgment, and the standards are appropriately tightened to make it difficult to enter the steady state condition, and to prevent repeated fluctuations before entering the steady state. Finally, if there is a steady state condition with a steady state duration of less than 5s, the data of this section will be eliminated.

[0055] The division of stable operating conditions is based on the average speed within the operating condition section, and one operating condition is the 1% range of high pressure relative to the physical speed.

[0056] The speed increase or decrease state of the working condition is judged based on the speed difference between two adjacent steady-state working conditions:

[0057] In the transition state, record the average speed of the previous steady state as the reference speed n of the speed change ref When it enters the steady state again, it is considered to have entered a new vibration stable working condition, and the sliding average of the speed is calculated. Compare the current speed with the reference speed of the transition state at the previous moment. If the difference in speed change is >2%, the current working condition is > the previous steady state working condition, which is an upward state, otherwise it is a downward state; if the difference in speed change is less than 2%, it is considered that the speed increase and decrease states of the two working conditions are consistent.

[0058] In addition, for aircraft engines, generally only the operating conditions at slow speed and above are studied, and the conditions where the high-pressure rotor speed is <65% are eliminated.

[0059] like Figure 5 As shown, the present invention can effectively identify the stable section and the transition section for the actual test speed, and correctly identify the speed increase and decrease state.

[0060] Example 2

[0061] like Figures 1 to 6 As shown, as a further optimization of Example 1, based on Example 1, this embodiment also includes the following technical features:

[0062] Step 1: Define the starting speed value and speed increase / deceleration state of a flight. When the data starts from startup, the speed value is set to 0, otherwise it is set to the starting value as the speed value of the previous stable working condition to fill the sliding window; the speed state is generally defined as a transition state, and the user can set it to a steady state; set the current working condition to be an ascending or descending state according to the actual situation. If it starts from startup, it is set to an ascending state.

[0063] Step 2: Read the speed data and store it in the sliding window. The sliding window is t long. The speed in the sliding window is that each time a new point is added, it is added to the end of the array and the first point in the array is removed.

[0064] Step 3: Calculate dn and n in the sliding window pp The value of , and the data in the sliding window is judged to be stable, and the result of the judgment is stored as the current state. The rule of judging stability is shown in Example 1.

[0065] The parameters have the following meanings:

[0066] dn: speed change value, the difference between the speed value at the last point of the sliding window and the speed value at the first point;

[0067] n pp : Speed ​​change amplitude: the difference between the maximum and minimum values ​​in the sliding window;

[0068] n: speed value;

[0069] The average speed in the stable section.

[0070] If the previous moment was a steady state, and data of T / 4 continuously appears in the T time period, it is considered to have entered the transition state. If the previous moment was a transition state, and the T time period is all steady state, it is considered to have entered the steady state. Otherwise, the state does not change.

[0071] Step 4: Store the result of steady-state judgment in the stable flag array stableflag within the T time period in a sliding window manner.

[0072] Step 5: If the state changes from steady state to transition state, the average speed and start and end time of the previous steady state are recorded and updated to the previous steady state. The current state is updated to transition state, and the reference speed is the average speed of the previous steady state.

[0073] Step 6: From the transition state to the steady state, update the current state to the steady state and start calculating the average speed of the current steady state condition. is the average speed within T time. According to the reference speed recorded in the transition state, the speed increase or decrease state of the current steady-state working condition is determined.

[0074] The speed increase and decrease state judgment rule is: compare the average speed of the current steady-state working condition with the average reference speed of the transition state. If |current average speed - reference speed|>2%, if the difference is positive, it is an increasing state, and if the difference is negative, it is a decreasing state; otherwise, it is considered to be the same state, which is consistent with the state of the previous working condition.

[0075] Step 7: If it is determined to be steady state and no state change occurs, update the steady state speed average. The speed average calculation formula is: in is the average speed, n is the speed value of the last point in the sliding window, and N is the accumulated speed points of the current working condition.

[0076] Step 8: If it is judged as a transition state and no state change occurs, no processing is performed.

[0077] Step 9: When the sliding window has experienced all the time points of a flight, the judgment is terminated. Eliminate all steady-state conditions that are less than the slow-speed state or the steady-state conditions with a stable duration of less than 5s. Extract all steady-state conditions and divide them into different conditions according to the high-pressure relative physical speed.

[0078] Parameter selection:

[0079] The sliding window Δt is set to 1s for reference control stability judgment; the δn in the stability judgment rule is set to 0.3% for the low-pressure rotor speed and 0.2% for the high-pressure rotor speed based on reference engine speed control rate. The amplification factor is set to 2 based on experience. The time resolution of general vibration analysis is lower than the sampling rate of speed acquisition. The time T for stability judgment observation is based on the time interval of vibration analysis, which is generally about 0.3-0.5s.

[0080] Threshold for whether the speed is consistent under working conditions: Summarize the characteristics of engine vibration data, take the speed difference of 100z as a significant difference, and set the threshold to 1% of the maximum speed. Whether there is an obvious speed change trend, the threshold for dividing the rising or falling state is set to 2%.

[0081] As described above, the present invention can be preferably implemented.

[0082] All features disclosed in all embodiments in this specification, or steps in all methods or processes implicitly disclosed, except for mutually exclusive features and / or steps, can be combined and / or expanded or replaced in any manner.

[0083] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. According to the technical essence of the present invention, within the spirit and principles of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for identifying steady-state vibration conditions of an aircraft engine, characterized in that: Whether the engine state is steady is determined based on the speed change law, and the operating conditions are divided according to the steady-state average speed and the speed change law between operating conditions.

2. The method for identifying the steady-state vibration condition of an aircraft engine according to claim 1, characterized in that: The following steps are involved: A1, defines the starting speed value and speed increase and decrease status of a flight; A2, reads the speed data and stores it in a sliding window with a length of Δt; A3, calculate dn and n in the sliding window pp The value of; where dn represents the speed change value, n pp Indicates the speed change amplitude; A4, perform steady-state judgment on the data in the sliding window, and use the steady-state judgment result as the current state; if the steady-state judgment result is steady-state, enter step A51X, and then enter step A5; if the steady-state judgment result is transitional state, enter step A51Y, and then enter step A5; wherein A51X is: update the stable segment information, and A51Y is: record the average speed of the stable segment as the reference speed of the transition segment; A5, determine whether the flight is ended: if so, end the flight; if not, return to step A2.

3. The method for identifying the steady-state vibration condition of an aircraft engine according to claim 2, characterized in that: In step A4, if the previous moment is a transition state, the condition for judging stability is: If dn<δn, and n pp <δn / 2, and the speed remains steady for a set period of time T, it is considered that the speed has entered the steady state stage; Among them, δn represents the stability threshold, and T represents the time interval of vibration analysis.

4. The method for identifying the steady-state vibration condition of an aircraft engine according to claim 2, characterized in that: In step A4, if the previous moment is a steady state, the condition for judging stability is: If dn<δn*c, and within a set period of time T, it continues to enter the transition state for T / 4 time, it is considered to have entered the transition state; Among them, δn represents the stability threshold, c represents the amplification factor, and T represents the time interval of vibration analysis.

5. The method for identifying the steady-state vibration condition of an aircraft engine according to claim 2, characterized in that: In step A4, when making a steady-state judgment, among all steady-state conditions, those in which the high-pressure rotor speed is lower than a set threshold or those in which the stable duration is shorter than a set time are eliminated.

6. The method for identifying the steady-state vibration condition of an aircraft engine according to claim 2, characterized in that: Step A51X includes the following steps: A51X1, calculate the speed characteristics of the stable stage: take the speed average n of the current steady-state condition as the speed average within T time; A51X2, determine whether the current stable segment is in an ascending or descending state; A51X3, updates the start and end time, speed average, rising state or falling state information of the stable segment.

7. The method for identifying the steady-state vibration condition of an aircraft engine according to claim 6, characterized in that: In step A51X3, the calculation formula for updating the average speed is: in, is the average speed, n is the speed value of the last point in the sliding window, and N is the accumulated speed points of the current working condition.

8. The method for identifying the steady-state vibration condition of an aircraft engine according to claim 6, characterized in that: In A51X2, the rule for judging whether the current stable segment is in an ascending state or a descending state is as follows: compare the average speed of the current steady-state condition with the reference speed of the transition state. If |current average speed - reference speed|> the set threshold, the difference is positive if it is an ascending state, and negative if it is a descending state; otherwise, it is considered to be the same state, which is consistent with the state of the previous condition; where || represents absolute value operation.

9. The method for identifying steady-state vibration conditions of an aircraft engine according to claim 1, characterized in that: The value of Δt is 1s.

10. A method for identifying steady-state vibration conditions of an aircraft engine according to any one of claims 3 to 9, characterized in that: The value of T is 0.3-0.5s.

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