CN212007508U - A device for measuring blade torsional vibration displacement - Google Patents

Abstract

The utility model relates to a device for measuring blade torsional vibration displacement, comprising a blade tip timing sensor, a photoelectric receiving device, a data acquisition and processing module and a signal processing system. The photoelectric receiving device outputs a photocurrent signal, and the photocurrent signal is amplified, After filtering, an analog signal is generated and transmitted to the data acquisition and processing module. The sensors are used to measure the time when the air inlet and outlet edges of a certain blade end reach the tip timing sensor in the same circle; the two blade tip timing sensors are set at the maximum displacement position of the torsional resonance blade end on the horizontal line of the stationary position of the blade end projection point. The utility model can be used to realize the measurement of the blade torsional vibration displacement.

Description

A device for measuring blade torsional vibration displacement

technical field

The utility model belongs to the field of rotating machinery state monitoring, in particular to a blade torsional vibration displacement measuring device based on the blade tip timing principle.

Background technique

Important rotating machinery such as aero-engines and steam turbines are the core components of key equipment such as military aircraft, commercial aircraft, generator sets and steam turbines in the aerospace and industrial fields. In particular, the moving blades are the core components of rotating machinery, and their working states directly affect the work efficiency and safety, stability, and long-term operation of these major key equipment. At present, the rotating blade vibration measurement technology based on the blade tip timing principle is a typical non-contact measurement method. The identification algorithm realizes the measurement of blade vibration parameters such as vibration amplitude, vibration frequency and vibration phase. Compared with the traditional offline blade condition detection method and online detection methods such as strain gauge method, frequency modulation method and acoustic method, the blade tip timing technology has the advantages of non-contact measurement, real-time online monitoring and measurement of all blades, so it has the advantages of relatively Good engineering practicality.

On the one hand, blades are one of the core components of large rotating machinery. Taking an aero-engine as an example, the working environment of the blade is relatively harsh under the working conditions. In addition to the centrifugal force, it is also continuously affected by the airflow excitation force, atmospheric temperature difference and high temperature. These external conditions produce relatively complex periodic stress on the rotating blades of the engine. When the frequency of the external excitation force is equal to or close to a certain order natural frequency of the blade, the blade may have blade cracks or blade fractures caused by resonance. Fault. According to statistics, failures caused by mechanical vibration account for more than 60% of the total number of aero-engine failures, and blade vibration failures account for more than 70% of the total number of mechanical vibration failures. It can be seen that blade vibration failure is an important cause of aero-engine failures. Therefore, research on blade It has important practical significance for the research and development testing, condition monitoring and fault diagnosis of important rotating machinery such as aero-engines and steam turbines.

On the other hand, when the blade is working, it is mainly subjected to the external periodically changing exciting force to generate forced vibration. According to the different forms of vibration, the blade vibration can be divided into three modes: bending vibration, torsional vibration and bending-torsional composite vibration. The same blade has multiple different resonance frequencies, which are divided into first-order resonance and second-order resonance according to the resonance frequency from small to large. When the external excitation force frequency is consistent with a certain-order resonance frequency of the blade, the blade will be excited to resonate. The mode shapes corresponding to different orders of resonance are not necessarily the same. In this utility model, the vibration of the blade vibration frequency not greater than its first-order resonance frequency is called low-order vibration, and the vibration of the blade vibration frequency greater than its first-order resonance frequency is called high-order vibration. Usually the mode shape of the first-order resonance of the blade is bending vibration, also called first-order bending vibration. The first-order bending vibration is the main cause of cracks and root fractures at the root of the blade. It is more harmful and the measurement method is relatively easy to implement. Therefore, the research on the first-order bending vibration at home and abroad is also more in-depth. Existing blade tip timing measurement methods, including the velocity vector end trace method ^[1] , the two-parameter method ^[2] , the autoregressive method ^[3] and the sensor-based arbitrary angle distribution method ^[4] , etc. Only one blade tip timing sensor is set in the direction of the position, so only the measurement of the blade bending vibration displacement can be realized, and the blade torsional vibration displacement measurement cannot be realized.

On the other hand, the modes of high-order vibration of the blade include three modes: bending vibration, torsional vibration and bending-torsional composite vibration. Blade cracks or angle drop faults caused by torsional vibration often occur, but because the high-order vibration of the blade has an amplitude of Due to the measurement problems such as small size, complex mode shape, and difficult sensor layout, there are few researches on the measurement methods of high-order blade vibration parameters at home and abroad, especially the measurement methods for parameters such as blade torsional vibration displacement have not been reported.

[1]I.Y.Zablotsky and Yu.A.Korostelev.Measurement of resonancevibrations of turbine blades with the ELURA device[J].Energomashinostroneniye,1970,Vol.2:36-39.

[2]S Heath.A New Technique for Identifying Synchronous ResonancesUsing Tip-Timing[J].Journal of Engineering for Gas Turbines and Power,2000,122(2):219-225.

[3] J. Gallego-Garrido, G. Dimitriadis, and J. R. Wright, A Class of Methods for the Analysis of Blade Tip Timing Data from Bladed Assemblies Undergoing Simultaneous Resonances—Part I: Theoretical Development [J]. International Journal of Rotating Machinery, 2007, Vol.2007:1-11.

[4] Ouyang Tao. Rotating blade vibration detection and parameter identification technology based on blade tip timing [D]. Doctoral dissertation, Tianjin University, 2011.

Utility model content

The purpose of the utility model is to provide a device for measuring the torsional vibration displacement of the blade, so as to overcome the disadvantage that the existing blade tip timing measuring device cannot measure the torsional vibration displacement of the blade. The technical scheme of the present utility model is as follows:

A device for measuring blade torsional vibration and displacement, including a blade tip timing sensor, a photoelectric receiving device, a data acquisition and processing module and a signal processing system, the photoelectric receiving device outputs a photocurrent signal, and the photocurrent signal is amplified and filtered to generate an analog signal The signal is transmitted to the data acquisition and processing module. There are two blade tip timing sensors. Two sets of blade tip timing sensors are arranged at the same circumferential position on the rotating machinery casing along the rotor axis, respectively for measuring a certain blade tip timing sensor. The time at which the air inlet and outlet edges of the blade tip reach the blade tip timing sensor in the same circle; the two blade tip timing sensors are set at the projection point of the maximum displacement position of the torsional resonance blade tip on the horizontal line of the stationary position of the blade tip.

The utility model overcomes the defect that the existing blade tip timing measurement method cannot measure the blade torsional vibration displacement, and proposes a blade torsional vibration displacement measurement device based on the blade tip timing principle. Two blade tip timing sensors are set in the direction to measure the time when the air inlet and outlet edges of a blade end reach the two blade tip timing sensors in the same circle. If supplemented by the software of the signal processing system, the blade twist can be realized. Accurate measurement of vibration displacement.

Description of drawings

Figure 1 shows the measurement structure of the tip timing principle

Figure 2 shows the structural diagram of the blade torsional vibration displacement measurement

Figure 3 shows the first-order torsional vibration mode diagram of the blade

Figure 4 shows a top view of the positioning of the blade torsional vibration displacement measurement sensor

Figure 5 shows a top view of the blade torsional vibration displacement measurement

Description of the labels in the figure:

In Figure 1, 1 is the blade tip timing sensor; 2 is the rotating mechanical casing; 3 is the blade;

In Fig. 2, 4 is the timing sensor of the inlet edge tip; 5 is the tip timing sensor of the outlet side; 6 is the air inlet edge of the blade end, 7 is the air outlet edge of the blade end, and 8 is the signal processing system;

In Fig. 3, 9 is the blade tip; 10 is the vibration node line; 11 is the vibration node;

In Fig. 4, 4 is the timing sensor of the blade tip of the intake side; 5 is the timing sensor of the blade tip of the outlet side; 11 is the vibration node; 12 is the maximum displacement position of the torsional resonance blade tip; 13 is the maximum deviation angle of the torsional resonance blade tip; 14 is the Displacement of the inlet side of the torsional resonance blade end; 15 is the displacement of the outlet side of the torsional resonance blade end; 16 is the static position of the blade end;

In Fig. 5, 2 is the rotating mechanical casing; 4 is the blade tip timing sensor of the intake side; 5 is the blade tip timing sensor of the outlet side; 12 is the maximum displacement position of the torsional resonance blade end; 16 is the stationary position of the blade end; 17 is the torsion 18 is the axial horizontal line of the rotor; 19 is the deflection angle of the blade end of torsional vibration; 20 is the displacement of the air inlet edge of the blade end measured by the sensor during torsional vibration; 21 is the displacement of the air outlet edge of the blade end measured by the sensor during torsional vibration ; 22 is the displacement of the real inlet edge of the blade end during torsional vibration; 23 is the displacement of the real outlet edge of the blade end during torsional vibration.

Detailed ways

The steps of manufacturing and operating the present utility model are described in detail below, and are intended to be described as embodiments of the present utility model, and are not the only form that can be manufactured or utilized. Other embodiments that can achieve the same function should also be included in the present utility model. In the range.

In this utility model, the tip of the blade is called the blade end, the circumferential direction of the rotating machine casing is called the circumferential direction, the side of the blade facing the airflow direction is called the intake side, and the side of the blade facing away from the airflow direction is called the outlet side. When the torsional vibration occurs, the circumferential distance difference generated by the blade tip edge passing through the two blade tip timing sensors on the inlet side and the outlet side in the same circle is called the blade torsional vibration displacement. example.

The principle structure measurement of blade tip timing is shown in Figure 1. The existing blade tip timing measurement method ^[1-4] is to set only one blade tip timing sensor 1 at the same circumferential position of the rotating machine casing 2. 3 When passing through the blade tip timing sensor 1, an arrival pulse signal will be generated, and the signal processing system uses the pulse time when the blade 3 reaches the blade tip timing sensor 1 to measure the blade bending vibration displacement;

The blade torsional vibration displacement measurement structure is shown in Figure 2. The method proposed by the present utility model installs two sets of blade tip timing sensors along the rotor axial direction at the same circumferential position of the rotating machinery casing. Vibration and torsional vibration of high-speed blades, measure the time when the air inlet edge 6 at the blade end reaches the blade tip timing sensor 4 at the inlet edge and the air outlet edge 7 at the blade end reaches the blade tip timing sensor 5 at the outlet edge; the blade tip timing sensor adopts a It is a fiber-optic bundle sensor composed of one transmitting fiber and multiple receiving fibers. The laser emits laser light through the transmitting fiber. When the air inlet edge 6 at the blade end and the air outlet edge 7 at the blade end reach the air inlet edge tip timing sensor 4 and the air outlet edge blade tip successively When the timing sensor 5 is used, multiple receiving optical fibers can receive the reflected light signal from the blade end, and transmit the signal to the photoelectric receiving device, and the photoelectric receiving device outputs the photocurrent signal. The photocurrent signal is amplified and filtered to generate a standard analog signal. It is transmitted to the data acquisition and processing module, and the signal processing system 8 realizes the measurement of the arrival time of the blade by collecting the time when the photocurrent signal occurs.

The first-order torsional vibration mode of the blade is shown in Figure 3. When the blade vibrates, the connection line formed by the points where the vibration displacement is zero on the blade body is called the vibration node line, and the intersection of the vibration node line and the blade tip is called the vibration node. When the first-order torsional vibration of the blade occurs, the air inlet and outlet edges of the blade end perform relative torsional motion around the blade vibration pitch line 10. The parameters such as the vibration pitch line 10, vibration node 11, resonance frequency and resonance amplitude can pass the blade natural frequency test. It is obtained that the vibration node line when the blade is subject to torsional vibration is not necessarily at the middle position of the blade body, so the vibration node 11 is not necessarily at the midpoint position of the blade end 9;

The positioning of the blade torsional vibration displacement measurement sensor is shown in Figure 4. When torsional vibration occurs on the blade, there are two situations: torsional non-resonance and torsional resonance. Choose a certain blade to be measured. When torsional vibration occurs, the blade end of the blade will be stationary at the blade end. Position 16 is the central position, and periodic torsional motion is performed between the two maximum displacement positions 12 of the torsional resonance blade tip. In order to ensure that the blade tip timing sensor can accurately measure the blade tip in the case of torsional non-resonance and torsional resonance of the blade The time signal of the air inlet and air outlet reaching the blade tip timing sensor, the positioning of the two blade tip timing sensors should be determined in combination with the blade torsional resonance parameters. The maximum displacement position of the torsional resonance blade tip 12 and the maximum deviation angle of the torsional resonance blade tip 13 can be Obtained through the natural frequency test of the blade, and the length of the blade tip can be obtained from the design drawings. Let α be the maximum deviation angle of the torsional resonance blade tip 13, O is the vibration node 11, line segment AB is the blade tip length, and E is the intake edge tip timing sensor 4 The installation position of , F is the installation position of the timing sensor 5 of the outlet edge tip, _h1 is the displacement ₁₄ of the intake side of the torsional resonance blade end, and h2 is the displacement 15 of the outlet edge of the torsional resonance blade end;

When the blade is in torsional resonance, the real-time position of the blade tip will periodically change between the two maximum displacement positions 12 of the torsional resonance blade tip. At this time, the maximum displacement position 12 of the torsional resonance blade tip is on the horizontal line where the stationary position 16 of the blade end is located. The projection of EF is the line segment EF, and the length of EF is the minimum value of the projected line segment of all the real-time positions of the blade tips on the horizontal line where the blade tip rest position 16 is located during the blade torsional vibration process. The maximum value of the angle, the displacement of the intake side of the torsional resonance blade end 14 and the displacement of the outlet side of the torsional resonance blade end 15 are the maximum values of the torsional displacement of all blades during the torsional vibration process. At point E, the tip timing sensor 5 of the outlet edge is installed at point F, which can ensure that in the case of torsional resonance of the blade, the two blade tip timing sensors can sample all the arrival time signals of the blade tip. The utility model calls this positioning The method is torsional resonance projection method;

When the blade is in a torsional non-resonance condition, the real-time position of the blade tip will perform periodic torsional motion between the two maximum displacement positions 12 of the torsional resonance blade tip (excluding the maximum displacement position 12 of the torsional resonance blade tip). The projection of the real-time position on the horizontal line where the stationary position 16 of the blade end is located will periodically change between the line segment EF (excluding points E and F) and the line segment AB. At this time, the two blade tip timing sensors located at points E and F are still It can sample all the time signals from the blade tip to the two blade tip timing sensors;

Since it cannot be confirmed that the blade is in torsional non-resonance or torsional resonance when it passes the blade tip timing sensor, if the installation position of the two blade tip timing sensors is moved from point E and point F to point O, although the torsional vibration blade can still be sampled However, when the blade is in torsional non-resonance and the vibration displacement of the blade is small, the time difference signal of the blade end passing through the two blade tip timing sensors is also small. At this time, if the signal processing system The accuracy of the blade is not high enough, and it may happen that the signal cannot be sampled; if the installation position of the two blade tip timing sensors is moved from point E and point F to point A and B, respectively, there will be torsional resonance or torsional non-resonance in the blade. When the vibration displacement is large, signal leakage sampling may occur. The sensor positioning method of the present invention can ensure that the maximum time difference signal or Because of the large time difference signal, the E and F points determined by the torsional resonance projection method can be used as the optimal positioning points of the sensor based on the blade torsional vibration measurement based on the blade tip timing principle;

(5) The displacement measurement of blade torsional vibration is shown in Figure 5. Let Ω _n1 be the low-speed rotation angular velocity of the rotor when the blade does not vibrate, Ω _n2 is the high-speed rotation angular velocity of the rotor when the blade has torsional vibration, and n is the number of rotations of the rotor , usually the blade end rest position 16 is not parallel to the rotor axial horizontal line 18,;

1. When the rotor rotates at a low speed with angular velocity Ω _n1 and the blade does not vibrate, the blade tip of the blade rotates through the inlet edge tip timing sensor 4 and the outlet edge tip timing sensor 5 and is always at the stationary position 16 of the blade tip. The time difference Δt _n1 = 0 when the circle reaches the blade tip timing sensor 4 on the intake side and the timing sensor 5 on the outlet side, and the torsional vibration displacement is 0;

2. When the rotor rotates at high speed with angular velocity Ω _n2 torsional vibration occurs, the real-time position of the blade tip when it rotates through the inlet edge tip timing sensor 4 and the outlet edge tip timing sensor 5 will be in the two torsion of the blade. Periodic changes between the maximum displacement positions 12 of the resonant blade tip, without loss of generality, select any real-time position 17 of the blade tip with torsional vibration when the blade rotates through the two blade tip timing sensors, and use the actual measurement of the blade tip to reach the nth circle. The time difference Δt _n2 between the inlet edge tip timing sensor 4 and the outlet edge tip timing sensor 5 can be calculated. When the blade rotates at a high speed of Ω _n2 and generates torsional vibration and passes through the two blade tip timing sensors, the blade tip rotates with the rotor. The circumferential arc length is:

L _n2 =Ω _n2 RΔt _n2 , n=1.2.3... (1)

In the formula, R is the radius of rotation of the blade tip. Since Δt _n2 is usually small, the circumferential arc length of the blade tip with the rotor rotating within the time difference of Δt _n2 is approximately equal to the inlet edge of the blade tip measured by the sensor during torsional vibration. The sum of the displacement 20 and the displacement 21 of the outlet edge of the blade end measured by the sensor during torsional vibration is:

L _n2 =Ω _n2 RΔt _n2 =h ₃ +h ₄ , n=1.2.3...(2)

In the formula, h ₃ is the displacement of the air inlet edge of the blade tip measured by the sensor during torsional vibration 20, h ₄ is the displacement of the air inlet edge of the blade end measured by the sensor during torsional vibration 21, combined with the torsional vibration blade tip deviation angle 19, the sensor during torsional vibration The displacement of the air inlet edge of the blade tip 20 is measured, the displacement of the outlet edge of the blade end 21 is measured by the sensor during torsional vibration, and the distance EF between the two blade tip timing sensors can be calculated. The value of the torsional vibration blade tip deviation angle 19:

In the formula, d is the distance between the two blade tip timing sensors, that is, the length of the line segment EF;

3. Since the positioning of the two blade tip timing sensors is based on the torsional resonance projection method, the intake edge tip timing sensor 4 and the outlet edge tip timing sensor 5 do not measure the arrival time of the blade tip edge, so by formula (2 ) The calculated L _n2 is not the real torsional vibration displacement of the blade; the torsional vibration blade tip deviation angle is 19, the sensor measures the blade tip air intake edge displacement during torsional vibration 20, and the sensor measures the blade tip outlet edge displacement 21 during torsional vibration, torsional vibration There is the following trigonometric function relationship between the real blade tip intake edge displacement 22 during vibration, the real blade tip outlet edge displacement 23 during torsional vibration, the distance between the two blade tip timing sensors and the blade tip length:

In the formula, h ₅ is the displacement of the actual air inlet edge of the blade end during torsional vibration 22, h ₆ is the actual displacement of the air outlet edge of the blade end during torsional vibration 23, p is the length of the blade end, that is, the line segment AB, combined with the trigonometric function in Eq. (4) relationship, the torsional vibration displacement generated by the blade rotating at high speed with angular velocity Ω _n2 through two blade tip timing sensors is:

The maximum deflection angle α of the blade tip of the torsional resonance can be obtained by the natural frequency test of the blade, the rotor rotation angular velocity Ω _n1 and Ω _n2 can be obtained by the actual measurement of the rotor tachometer system, the blade tip rotation radius R, the blade tip length p and the timing of the two blade tips The distance d between the sensors can be obtained from the design drawings, and the time differences Δt _n1 and Δt _n2 between the blade tip and the two blades reaching the blade tip timing sensors can be obtained from the actual measurement of the blade tip timing sensors.

Claims (1)

1. A device for measuring blade torsional vibration and displacement, including a blade tip timing sensor, a photoelectric receiving device, a data acquisition and processing module and a signal processing system. The photoelectric receiving device outputs a photocurrent signal, and the photocurrent signal is amplified and filtered. An analog signal is generated and transmitted to the data acquisition and processing module, characterized in that there are two blade tip timing sensors, and two groups of blade tip timing sensors are arranged at the same circumferential position on the rotating machinery casing along the rotor axis, They are used to measure the time when the air inlet and outlet edges of a blade end reach the blade tip timing sensor in the same circle; the two blade tip timing sensors are set at the projection of the maximum displacement position of the torsional resonance blade end on the horizontal line of the stationary position of the blade end. point.

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