Method for predicting theoretical moment of blade reaching blade tip timing probe without rotating speed signal

Abstract

The invention relates to a method for predicting a theoretical moment when a blade without a rotating speed signal reaches a blade tip timing probe. The method comprises the steps of obtaining the actual arrival time of N blades reaching m blade tip timing probes in the circumferential direction of the blades, obtaining the rotating shaft rotating speed value in a vibration-free state through reconstruction based on the actual arrival time of the N blades, and reconstructing the theoretical time value of the N blades reaching the m blade tip timing probes according to the rotating shaft rotating speed value. According to the method, the stability of data measurement in the aero-engine vibration experiment can be improved, the requirement for the experiment environment is reduced, a vibration measurement system can be simplified, and the method has important practical application value in the development process of aero-engines.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of impeller design, and particularly relates to a theoretical time prediction method of a blade tip timing probe without a rotating speed signal BACKGROUND

[0002] In modernized aero-engine compression systems, the compression system is required to have the characteristics of high pressure ratio, high efficiency, high reliability, long service life and light weight, which makes the aerodynamic load of the compressor blade continuously increase, the blade thickness continuously decrease, and the stiffness decrease. Current fan / compressor rotor design increasingly tends to adopt the blisk scheme, which reduces the structural damping while reducing the weight of the compressor. These aspects will increase the possibility of blade vibration problems in complex and severe flow environment.

[0003] Early blade vibration measurement in aero-engines mainly uses strain gauges. In recent years, with the gradual popularization of non-contact measurement, vibration measurement technology based on the blade tip timing principle has been widely used in research institutes. Currently, commercialized blade tip timing systems usually have a rotating speed probe (OPR probe, Once-per-revolution), which can measure the rotating speed of each rotating shaft cycle in real time, and is used to analyze the theoretical arrival time of the blade in the non-vibration state.

[0004] The rotating speed probe has two components: a stationary component and a rotating component. The stationary component is a sensor fixed in the mounting hole of the casing; the rotating component is usually fixed on the engine shaft and rotates with the shaft. However, in engineering practice, the rotating component of the rotating speed probe may be limited by insufficient installation space, complex installation conditions, or engine internal environment pollution, and cannot be used normally.

[0005] Taking the products of the American HOOD company and the British EMTD company commonly used in aero-engine main machines as examples, the rotating speed probe must be installed to perform accurate vibration measurement experiments. Once the rotating speed probe is contaminated, it will seriously affect the accuracy of vibration measurement, and even lead to the failure of measurement, thereby increasing the uncertainty of aero-engine vibration experiments. And the small-sized aero-engine and the high-pressure stage (blade stage with smaller blade size) in the larger-sized aero-engine are facing increasingly serious vibration problems, which makes it difficult for the rotating component of the rotating speed probe to be effectively installed in the narrow internal space of the aero-engine.

[0006] Therefore, it is necessary to develop a blade tip timing data analysis method without a rotating speed signal, so as to realize real-time monitoring of all blade vibration characteristics under the condition of only having a blade tip timing probe without a rotating speed probe. SUMMARY

[0007] The present application aims at avoiding the defects of the prior art to provide a theoretical time prediction method for a blade-to-tips timing probe without a rotating speed signal, which can solve the problem that the existing blade-to-tips timing system cannot be normally used due to the insufficient installation space, complex installation conditions or internal environmental pollution of the engine.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a theoretical time prediction method for a blade-to-tips timing probe without a rotating speed signal, comprising the following steps:

[0009] Step one: collecting the actual arrival time of N blades to m blade-to-tips timing probes in i rotating shaft rotation periods, and naming the m blade-to-tips timing probes in the order of installation angle from small to large as the 1st, 2nd, …, mth blade-to-tips timing probes, taking any blade in the N blades as the 1st blade, and then naming the 2nd, 3rd, …, Nth blades;

[0010] Step two: reconstructing the rotating shaft rotating speed value in the non-vibration state based on the actual arrival time of the N blades;

[0011] Step three: reconstructing the theoretical time value of the N blades to the m blade-to-tips timing probes according to the rotating shaft rotating speed value.

[0012] Further, the step one is specifically:

[0013] According to the installation angle of the m blade-to-tips timing probes in the blade circumferential direction, the actual arrival time data of the N blades measured by each blade-to-tips timing probe is extracted, and the time data is separated to obtain the actual arrival time of the N blades to the m blade-to-tips timing probes in the i rotating shaft rotation period, at this time, each blade corresponds to m actual arrival times;

[0014] Wherein, one rotating shaft rotation period is the difference between the first time data and the N+1th time data collected by any blade-to-tips timing probe, which is 360 degrees of rotating shaft rotation.

[0015] Further, the step two is specifically:

[0016] In i rotating shaft rotation periods, the rotating shaft rotating speed value recovered through any blade is represented as:

[0017]

[0018] In the formula, i is the number of rotating shaft rotation periods, j is the blade number, k is the circumferential blade-to-tips timing probe number, m is the total number of circumferential blade-to-tips timing probes, r i,j is the rotating speed value reconstructed by the actual arrival time of the jth blade in the ith rotating shaft rotation period, the unit is revolution per second, Ti,j,k the actual arrival time of the jth blade measured by the kth tip timing probe in the ith rotation period of the rotor shaft;

[0019] Then, the same calculation method is taken for all the blades, and the rotor shaft speed value in each rotation period of the rotor shaft is reconstructed by the actual arrival time of all the blades, and the expression is:

[0020]

[0021] In the formula, RPS i is the rotor shaft speed value reconstructed by the actual arrival time of all the blades in the ith rotation period of the rotor shaft, and the unit is revolutions per second.

[0022] Further, the third step is specifically:

[0023] The theoretical arrival time of any blade to the tip timing probe is expressed as:

[0024]

[0025] In the formula, Tideal i,1,1 is the theoretical arrival time of the first blade to the first tip timing probe in the ith rotation period of the rotor shaft, theta 1,k is the difference between the circumferential installation angle of the kth tip timing probe and the first tip timing probe;

[0026] Then, the theoretical arrival time of any blade to each tip timing probe in the non-vibration state is expressed as:

[0027]

[0028] In the formula, Tideal i,1,k is the theoretical arrival time of the first blade to the kth tip timing probe in the ith rotation period of the rotor shaft;

[0029] The same calculation method is taken for all the blades, and the theoretical arrival time Tideal i,j,k of each blade to each tip timing probe in each rotation period of the rotor shaft is obtained. i is the rotor shaft speed value reconstructed by the actual arrival time of all the blades in the ith rotation period of the rotor shaft, and the unit is revolutions per second.

[0030] Further, the tip timing probe is arranged on the casing at any circumferential angle, and when the blade arrives at the tip timing probe, a tip pulse signal is triggered, which is recorded as the actual arrival time of any blade to the m tip timing probes on the circumferential direction of the casing.

[0031] The tip timing probe and the signal collection instrument for receiving the tip pulse signal constitute a tip timing system.

[0032] The method has the advantages that: the method only needs to set a sensor mounting hole on the casing, does not need to install a rotating part of a rotating speed probe on a rotating shaft, can realize real-time monitoring of vibration characteristics of all blades, and has the specific implementation effects that:

[0033] 1) the method can analyze vibration frequency, vibration amplitude, circumferential pitch diameter number and maximum stress and corresponding positions of the blade by collected data in only 1s time span, and provides a reference for troubleshooting of non-synchronous vibration faults of the engine blade.

[0034] 2) the method can greatly simplify an aero-engine vibration experiment process, only needs to open a hole on the casing to install a tip timing sensor, and can complete blade vibration measurement, thereby effectively reducing experiment difficulty and cost, and improving stability and reliability of vibration experiment data measurement.

[0035] That is, the method can not only improve stability of data measurement in the aero-engine vibration experiment, reduce requirements on an experiment environment, but also simplify a vibration measurement system, and has important practical application value in the development process of the aero-engine. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a schematic diagram of the tip timing principle described in the application;

[0037] Figure 2 is a schematic diagram of the tip timing data analysis principle described in the application;

[0038] Figure 3 is a reconstructed rotating speed value RPS of the i-th circle of all blades actually arriving at the moment; i and a comparison with a measurement result of the rotating speed probe;

[0039] Figure 4 is a theoretical moment of the blade arriving at the first tip timing probe, and a comparison with a result of conventional rotating speed probe calculation;

[0040] Figure 5 is a displacement diagram of all blades measured at each tip timing probe;

[0041] Figure 6 is a frequency spectrum diagram obtained by performing fast Fourier transform on the blade vibration displacement data;

[0042] Figure 7 is a vibration phase diagram of different blades in the circumferential direction. DETAILED DESCRIPTION

[0043] The principles and features of the present application are described below in conjunction with the accompanying drawings, in which the examples are used to explain the present application and are not intended to limit the scope of the present application.

[0044] To achieve the above-mentioned purpose, the present application provides the following specific embodiments:

[0045] Embodiment 1: A theoretical time prediction method of a blade arrival tip timing probe without a speed signal, comprising the following steps:

[0046] S01, according to the installation angle of the m tip timing probes in the circumferential direction of the blade, extracting the actual arrival time data of N blades measured by each tip timing probe, and separating the time data to obtain the actual arrival time of N blades to the m tip timing probes in the i th rotation period of the shaft, at this time, each blade corresponds to m actual arrival times;

[0047] Wherein, one rotation period of the shaft is the difference between the first time data and the N+1 time data collected by any tip timing probe, which is 360 degrees of rotation of the shaft.

[0048] S02, the m tip timing probes are sequentially named as the 1st, 2nd, …, mth tip timing probes according to the installation angle from small to large in the circumferential direction; any blade in the N blades is taken as the 1st blade, and then sequentially named as the 2nd, 3rd, …, Nth blade;

[0049] S03, in the i th rotation period of the shaft, the shaft speed value recovered through any blade is represented as:

[0050]

[0051] In the formula, i is the number of rotation periods of the shaft, j is the blade number, k is the circumferential tip timing probe number, m is the total number of circumferential tip timing probes, r i,j is the speed value reconstructed by the actual arrival time of the j th blade through the i th rotation period of the shaft, unit: revolution per second, T i,j,k is the actual arrival time of the j th blade measured by the k th tip timing probe in the i th rotation;

[0052] S04, the same calculation method is adopted for all blades, and the speed value of the shaft in each rotation period of the shaft is reconstructed by the actual arrival time of all blades, and the expression is:

[0053]

[0054] In the formula, RPS iThe theoretical arrival time of any blade to the blade tip timing probe is represented as:

[0055] S05、The theoretical arrival time of any blade to the blade tip timing probe is represented as:

[0056]

[0057] In the formula, Tideal i,1,1 The theoretical arrival time of the first blade to the first blade tip timing probe in the i-th rotation period of the rotating shaft is represented as theta 1,k The difference between the circumferential installation angle of the k-th blade tip timing probe and the first blade tip timing probe is represented as delta

[0058] The theoretical arrival time of any blade to each blade tip timing probe in the non-vibration state is represented as:

[0059]

[0060] In the formula, Tideal i,1,k The theoretical arrival time of the first blade to the k-th blade tip timing probe in the i-th rotation period of the rotating shaft is represented as theta

[0061] S06、The same calculation method is adopted for all blades, that is, the theoretical arrival time Tideal i,j,k of each blade to each blade tip timing probe in each rotation period of the rotating shaft is obtained. i The rotating speed value of the rotating shaft reconstructed by the actual arrival time of all blades in the i-th rotation period of the rotating shaft is represented as RPS

[0062] In the embodiment 2, the blade tip timing probe is arranged on the casing at an arbitrary circumferential angle, and when the blade arrives at the blade tip timing probe, a blade tip pulse signal is triggered, which is represented as the actual arrival time of any blade to the m blade tip timing probes on the circumferential direction of the casing.

[0063] The blade tip timing probe and the signal acquisition instrument for receiving the blade tip pulse signal form a blade tip timing system, and the method is completed by using the system.

[0064] As Figures 1-7 shown, in order to further illustrate the technical scheme and technical effect of the present application, the following specific examples are provided:

[0065] The blade vibration signal acquisition scheme based on the non-rotating speed blade tip timing principle is as Figure 1 shown. Figure 2As shown, the blade tip timing signal is measured by a fiber sensor, i.e. a blade-tip-timing (BTT) probe, and in this scheme, a rotational speed probe for measuring the rotational speed is no longer needed.

[0066] The blade tip timing probe is installed at different positions in the circumference of the casing, and is usually arranged in a non-uniform layout, and the specific circumferential installation angle is usually a specified angle. When the blade passes through the blade tip timing probe, a pulse signal is triggered to record the arrival time value of the current blade.

[0067] Figure 1 And Figure 2 The hardware of the acquisition system shown in the figure is composed of a conventional probe (sensor) and a signal acquisition instrument, which has been disclosed in the invention patent with the publication number CN119203694A. The present application is based on the core difficulty of blade tip timing technology for analyzing blade vibration characteristics according to the time value signals collected by the device shown or other devices used in other fields, and provides the following specific examples:

[0068] Under a certain experimental condition, blade tip timing measurement was taken on a 1.5-stage fan containing an inlet adjustable guide vane, a rotor and a stator. Five blade tip timing probes and a rotational speed probe were arranged on the casing to obtain the vibration characteristics of the rotor blades. At the same time, in order to verify the blade tip timing analysis results, strain gauges at the blade tip and dynamic fluctuating pressure measurement of the casing were also taken, and finally it was confirmed that the blade occurred non-synchronous vibration under this condition. According to the measured blade tip timing data, the method for analyzing the theoretical arrival time of the blade based on the blade tip timing principle includes the following steps:

[0069] (1) Extract all the actual arrival times of the blades measured by the blade tip timing probe during the experiment. At the same time, process the data of the rotational speed probe to verify the blade theoretical arrival time prediction method based on the blade tip timing principle developed in this application.

[0070] (2) Since each blade tip timing probe measures the arrival time of all blades in turn, according to the circumferential installation angle and the number of blades, etc., the data collected at the five blade tip timing probes are separated into 19 groups of data (the number of rotor blades is 19) in the order of blades. Each group of data corresponds to the measurement results of a blade at the five probes.

[0071] (3) According to the measurement data in (2), use the method described in step four to analyze and obtain the rotational speed value RPS of the i-th turn reconstructed by all the actual arrival times of the blades i , and compare it with the result measured by the rotational speed probe Figure 3 as shown;

[0072] FromFigure 3 It can be seen from the figure that the shaft speed value reconstructed by the method described in the present application is completely consistent with the result measured by the shaft speed probe. The unit of the ordinate in the figure is only 0.1 Hz, which indicates that the error between the present method and the direct measurement result of the shaft speed probe is far less than 0.1 Hz, further illustrating the accuracy of the present method.

[0073] (4) Using the method described in step five, the theoretical time when the blade 1 reaches the first blade tip timing probe can be calculated based on the shaft speed value of the shaft in each shaft rotation period calculated in (3), and compared with the result calculated by the conventional shaft speed probe, and the result is shown in Figure 4

[0074] It can be seen from Figure 4 that even without using the data of the shaft speed probe, the theoretical time accuracy consistent with the shaft speed probe can still be obtained. Combined with the shaft speed value calculated in step four, the theoretical arrival time when the blade 1 reaches each blade tip timing probe in a non-vibration state can be calculated using the method described in step five.

[0075] The same calculation is performed for all blades to obtain the theoretical arrival time Tideal of each blade at each blade tip timing probe in each shaft rotation period. i,j,k Combined with the actual arrival time Treal of all blades measured at the blade tip timing probe, i,j,k the displacement of all blades measured at each blade tip timing probe can be calculated, and the result is shown in Figure 5

[0076] Figure 5 In the figure, the left graph is the vibration displacement of all blades calculated by the method described in the present application, and the right graph is the vibration displacement of all blades calculated based on the conventional shaft speed probe experimental scheme. It can be seen that the amplitude of the blade vibration measured by the two experimental schemes is basically consistent.

[0077] Meanwhile, the blade vibration displacement data measured by the two experimental schemes is subjected to fast Fourier transform, and the frequency spectrum diagram obtained is shown in Figure 6

[0078] It can be seen from Figure 6 that the blade vibration frequency in the analysis result of the shaft speed probe-free scheme developed in the present application is completely consistent with that of the shaft speed probe scheme, and the Fourier coefficient amplitude is also very close, and the overall frequency spectrum diagram is also very close.

[0079] Based on the above analysis, the displacement of the blade can be least square fitted to obtain the vibration phase of different circumferential blades, and the result is shown in Figure 7 ​​​​

[0080] From Figure 7 It can be seen from the above that the blade theory arrival time prediction method based on the blade tip timing principle described in the present application can accurately capture the blade vibration pitch diameter consistent with the conventional rotational speed tip timing data analysis method.

[0081] The characteristic parameters of the blade asynchronous vibration can be quickly and accurately analyzed under the condition of no rotational speed probe by the above steps, real-time vibration early warning is realized, and reference is provided for the fluid-structure coupling mechanism and vibration reduction design of the blade asynchronous vibration.

[0082] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for predicting the theoretical time when a blade reaches a blade tip timing probe without a speed signal, characterized in that: The following steps are involved: Step 1: Collect the actual arrival times of N blades at m blade tip timing probes on the blade circumference within i rotation cycles of the shaft, and name the m blade tip timing probes as the 1st, 2nd, ..., mth blade tip timing probes in ascending order of their circumferential installation angles. Take any blade among the N blades as the first blade, and then name them as the 2nd, 3rd, ..., Nth blades in sequence. Step 2: reconstruct the shaft speed value in a vibration-free state based on the actual arrival time of the N blades; Step 3: Reconstruct the theoretical time values ​​of the N blades reaching the m blade tip timing probes based on the shaft speed value.

2. The method for predicting the theoretical time when a blade reaches a blade tip timing probe without a rotation speed signal according to claim 1, characterized in that: The step 1 is specifically as follows: Based on the installation angles of the m blade tip timing probes on the blade circumference, the actual arrival time data of the N blades measured by each blade tip timing probe are extracted and separated to obtain the actual arrival time of the N blades reaching the m blade tip timing probes during the i-th rotation period of the shaft. In this case, each blade corresponds to m actual arrival times. Among them, one shaft rotation cycle is the difference between the first moment data and the N+1th moment data collected by any blade tip timing probe, which is 360 degrees of shaft rotation.

3. The method for predicting the theoretical time when a blade reaches a blade tip timing probe without a rotation speed signal according to claim 1, characterized in that: The step 2 is specifically as follows: During i rotation cycles of the shaft, the shaft speed value recovered by any blade is expressed as: Where i is the number of rotation cycles of the shaft, j is the blade number, k is the number of the circumferential blade tip timing probe, m is the total number of circumferential blade tip timing probes, and r is the number of the blade tip timing probes. i,j T is the speed value reconstructed from the actual arrival time of the jth blade during the i-th shaft rotation cycle, in revolutions per second. i,j,k is the actual arrival time of the jth blade measured by the kth blade tip timing probe during the i-th shaft rotation period; Then, the same calculation method is adopted for all blades, and the actual arrival time of all blades is reconstructed to obtain the rotation speed value of the shaft in each rotation cycle of the shaft: Among them, RPS i is the shaft speed value reconstructed from the actual arrival time of all blades within i shaft rotation cycles, in revolutions per second.

4. The method for predicting the theoretical time when a blade reaches a blade tip timing probe without a rotation speed signal according to claim 1, characterized in that: The step three is specifically as follows: The theoretical arrival time of any blade at the blade tip timing probe is expressed as: Where, Tideal i,1,1 Theta is the theoretical arrival time of the first blade at the first blade tip in the i-th rotation cycle. 1,k is the difference in circumferential installation angle between the kth blade tip timing probe and the first blade tip timing probe; Then, in the non-vibration state, the theoretical arrival time of any blade at each blade tip timing probe is expressed as: Among them, Tideal i,1,k is the theoretical arrival time of the first blade at the k-th blade tip timing probe within the i-th shaft rotation period; The same calculation method is used for all blades, that is, the theoretical arrival time Tideal of each blade at each blade tip timing probe in each shaft rotation cycle is obtained. i,j,k , RPS i is the shaft speed value reconstructed from the actual arrival time of all blades within i shaft rotation cycles, in revolutions per second.

5. The method for predicting the theoretical time when a blade reaches a blade tip timing probe without a rotation speed signal according to any one of claims 1 to 4, characterized in that: The blade tip timing probe is set on the casing at any circumferential angle. When the blade reaches the blade tip timing probe, a blade tip pulse signal is triggered, which is recorded as the actual arrival time of any blade at the m blade tip timing probes on the circumference of the casing. The blade tip timing probe and the signal acquisition instrument for receiving the blade tip pulse signal constitute the blade tip timing system.

Images