RU2324161C2 - Device for diagnostics of self-vibrations of turbo machine engine disk - Google Patents

Abstract

FIELD: engineering industry; power-plant enginnering.

SUBSTANCE: there is signal-conditioner box, first and second amplitude detector, threshold device and comparator, which lead to the device of diagnostics of self-vibrations of turbo machine engine disk containing two active tunable band pass filters, AND circuit with the outlet connected to the indicator through a matching amplifier. The first device inlet is the first tunable active bandpass filter information inlet, and the second one is the signal-conditioner box inlet, and the third device inlet is the second tunable active bandpass filter information inlet, the driving points of the first and second tunable bandpass filters being connected to each other and to the first signal-conditioner box outlet, which has its second outlet connected to the threshold device driving point; the first tunable active bandpass filter outlet is connected through the first amplitude detector to the threshold device information outlet, which in turn is connected with its outlet to one of the AND circuit outlets; the second active tunable bandpass filter is connected to another AND circuit inlet through the cascade connection of the second amplitude detector and the comparator circuit; the second comparator circuit is connected to the reference-voltage source, and the device outlet is connected to the matching amplifier outlet.

EFFECT: effectiveness and reliability increase of diagnostics of self-vibrations of turbo machine engine disk vanes in real time mode.

3 cl, 3 dwg

Description

The present invention relates to aircraft engine building and power machine building and can be used for strength tuning of gas turbine engine compressors, as well as for the diagnosis of self-oscillations in the process of bench testing and operation.

A device is known for diagnosing auto-oscillations of the impeller of a turbomachine, comprising a coincidence circuit, the output of which is connected to an indicator through an amplifier. (Zabolotsky N.E. Non-contact measurements of vibrations of turbomachine blades - M .: Mashinostroenie, 1977, S.91-92).

This device does not allow with high reliability to detect the diagnostic frequency of self-oscillations, because the diagnostic result depends on the gap between the sensor and the blades, which in turn depends on many uncontrollable factors and, as a result, is not reliable enough. In this case, a capacitive or inductive sensor is used, placed in the housing in the area of the periphery of the impeller blades.

Closest to the proposed device is a device for diagnosing auto-oscillations of the impeller of a turbomachine, containing two tunable active bandpass filters, a coincidence circuit, the output of which is connected through an amplifier to an indicator (patent RU 2094618, IPC 6 F01D 25/04, publication date 1997.10.27).

This device also does not allow with high reliability to detect the diagnostic frequency of auto-oscillations due to the need to diagnose auto-oscillations in a wide frequency band of the pulsation signal, the upper boundary of which exceeds the value of the repetition rate of the blades, equal to the product of the rotational speed of the impeller by the number of blades mounted on it. In addition, since the values of the useful components in the pulsating signal, the difference of which judges the presence of self-oscillations, are commensurate with the level of acoustic noise, it is difficult to diagnose self-oscillations in real time due to the difficulty of isolating diagnostic frequencies from a noisy broadband signal.

All this reduces the efficiency and reliability of the device and increases the cost of its implementation.

The technical result to which the invention is directed is to increase the efficiency and reliability of the diagnosis of auto-oscillations of the blades of the impeller blades of a turbomachine in real time.

The technical result is achieved by the fact that in the device for diagnosing auto-oscillations of the impeller of a turbomachine, containing two tunable active bandpass filters, a coincidence circuit whose output is connected to an indicator through a matching amplifier, in contrast to the known signal shaper, first and second amplitude detectors, a threshold device and a comparator, wherein the first input of the device is the information input of the first tunable active bandpass filter, the second input of the device is the signal former is input, the third input of the device is the information input of the second tunable active band-pass filter, the control inputs of the first and second tunable active band-pass filters are connected to each other and to the first output of the signal shaper, the second output of which is connected to the control input of the threshold device; the output of the first tunable active bandpass filter through the first amplitude detector is connected to the information input of the threshold device, the output of which is connected to one of the inputs of the coincidence circuit; the output of the second tunable active band-pass filter through a second amplitude detector and a comparator connected in series to another input of the coincidence circuit; the second input of the comparator is connected to a reference voltage source, and the output of the device is connected to the output of the matching amplifier.

The signal conditioner may comprise a pulse shaper, a pulse counter, a read-only memory, and a digital-to-analog converter, the output of which is the first output of the signal conditioner, the second output of which is connected to the output of the pulse counter, and the input of the signal conditioner is connected to the input of the pulse conditioner.

The threshold device may include first and second sampling-storage devices, the outputs of which are connected to the inputs of a differential amplifier, the output of which through the first comparator is connected to one of the key inputs, the output of the second comparator is connected to the other input, the key output is the output of the threshold device; the information inputs of the sampling-storage devices and the input of the second comparator are interconnected with the information input of the threshold device, the control inputs of the sampling-storage devices are interconnected with the control input of the threshold device, the second inputs of the comparators are connected to voltage reference sources.

The technical result is achieved through the use as the main dynamic parameter - housing vibration and an additional dynamic parameter - pulsation of the flow pressure. Moreover, both parameters - case vibration and pulsation of flow pressures - are recorded in a limited frequency band in order to eliminate redundant information that impedes diagnosis. In this case, the signal from the ripple sensor does not contain a component with the repetition frequency of the impeller blades, which complicates the diagnosis, since it may exceed the useful signal in level. The appearance of a diagnostic frequency in the spectrum of pulsations of flow pressures is an additional diagnostic feature that confirms the occurrence of self-oscillations in order to timely detect and prevent dangerous stresses in the blades. All this makes it possible to determine the diagnostic frequency in the spectra of vibration and pulsation signals in a narrower frequency range with an amplitude exceeding the noise level characteristic of real turbomachines.

The invention is illustrated by drawings:

figure 1 is a functional block diagram of a device for diagnosing auto-oscillations of the impeller of a turbomachine;

figure 2 is a functional block diagram of a signal conditioner;

figure 3 is a functional block diagram of a threshold device.

A device for diagnosing auto-oscillations of the impeller of a turbomachine (Fig. 1) contains the first and second tunable active band-pass filters 1 and 2 and a signal shaper 3. The information input of the first tunable active band-pass filter 1 is the first input of the device, the second input of which is connected to the input of the signal shaper 3 and the third input with the information input of the second tunable active bandpass filter 2.

The control inputs of the first and second tunable active bandpass filters 1 and 2 are interconnected and with the first outputs of the signal conditioner 3.

The output of the first tunable active band-pass filter 1 through the first amplitude detector 4 is connected to the information input of the threshold device 5, the control input of which is connected to the second output of the signal conditioner 3, and the output of the threshold device 5 is connected to one of the inputs of the matching circuit 6.

The output of the second tunable active band-pass filter 2 through a second amplitude detector 7 and a comparator 8 connected in series is connected to another input of the matching circuit 6. The second input of the comparator 8 is connected to a reference voltage source.

The output of the matching circuit 6 through the matching amplifier 9 is connected to the indicator 10. The output of the device is connected to the output of the matching amplifier 9.

Signal conditioner 3 (Fig. 2) contains a pulse shaper 11 connected in series, pulse counter 12, read-only memory 13 and digital-to-analog converter 14, the output of which is the first output of signal shaper 3. The second output of signal shaper 3 is connected to the output of pulse counter 12. Input pulse shaper 11 is the input of the signal shaper 3.

The threshold device 5 (Fig. 3) contains the first and second sampling and storage devices 15 and 16, the outputs of which are connected to the inputs of the differential amplifier 17, the output of which through the first comparator 18 is connected to one of the inputs of the key 19, to the other input of which the output of the second comparator 20. The second inputs of the comparators 18 and 20 are connected to voltage reference sources. The output of the key 19 is the output of the threshold device 5. The information inputs of the sample-storage devices 15 and 16 and the input of the second comparator 20 are connected to each other and to the information input of the threshold device 5. The control inputs of the sample-storage devices 15 and 16 are connected to each other and to the control input threshold device 5.

The device operates as follows.

The signal from the standard vibration sensor located near the blades of the impeller of the turbomachine, measuring the body vibration, is fed to the first input of the device for diagnosing auto-oscillations of the impeller of the turbomachine (Fig. 1), connected to the information input of the active band-pass filter 1, which is tunable in frequency by the signal generated by the signal conditioner 3.

The signal from the ripple sensor, located near the blades of the impeller of the turbomachine, which measures the flow pulsation, is fed to the third input of the device for diagnosing auto-oscillations of the impeller of the turbomachine (Fig. 1), connected to the information input of the active band-pass filter 2, tunable in frequency with the same signal, generated by the signal shaper 3.

At the input of the signal shaper 3 receives a periodic signal from the speed sensor. The signal generator 3 generates from a periodic input signal with a rotational speed of the impeller f _p at its outputs signals with frequencies f _v and f _m , which are related by the ratio:

f _v = f _m + zf _p ,

where f _v is the diagnostic frequency of the oscillations of the blades observed during self-oscillations;

f _m is the natural frequency of oscillation of the blades;

z = 1 ÷ 4 - number of the natural form of vibration with the number of nodal diameters of the oscillations of the impeller;

f _p - frequency of rotation of the impeller of the turbomachine.

A signal with a diagnostic frequency f _{v is} supplied to the combined control inputs of tunable active bandpass filters 1 and 2 and tunes them to a frequency f _v . In addition, the signal shaper 3 generates pulses with a repetition rate equal to the set value of the change in the frequency of rotation of the impeller, arriving at the control input of the threshold device 5.

From the outputs of tunable active bandpass filters 1 and 2, the signals are fed to amplitude detectors 4 and 7, which emit envelopes of the signals received at the information input of the threshold device 5 and the first input of the comparator 8.

When self-oscillations occur, the threshold device 5 generates at its output a signal supplied to one of the inputs of the coincidence circuit 6. The comparator 8 compares the signal from the output of the amplitude detector 7 with the reference voltage supplied to its second input and generates an output signal to another input of coincidence circuit 6 in the presence of a component with a diagnostic frequency f _v in the pulse signal, which confirms the occurrence of self-oscillations of the impeller of the turbomachine.

Matching circuit 6, executed on a logic element, if there are two signals at the same time, generates a signal indicating the occurrence of self-oscillations, fed to the matching amplifier 9, indicator 10 and to the output of the device, which is connected, for example, to a fuel dispenser that generates self-oscillations command to the actuator to reduce the operation of the turbomachine.

Signal conditioner 3 operates as follows.

A periodic signal from the speed sensor is fed to the input of the signal shaper 3 (Fig. 2) and the input of the pulse shaper 11. The pulse shaper 11 generates a digital signal from the periodic signal that goes to the input of the pulse counter 12, which generates a series of pulses from this signal at intervals equal to the set value of the change in the frequency of rotation of the impeller of the turbomachine, controlling the threshold device 5, and the address code of the permanent storage device 13. In the permanent memory 13 the dependences of the diagnostic frequency on the impeller rotation frequency are obtained, with the number of nodal diameters z = 1-4, established by calculation or experimentally, generated by pulses coming from the output of the pulse counter 12. The signal from the output of the permanent storage device 13 is converted by a digital-to-analog converter 14 from a digital code into an analog signal with a diagnostic frequency, i.e. A signal with a diagnostic frequency f _v , which is necessary to control tunable active bandpass filters 1 and 2, is modeled.

The threshold device 5 operates as follows. The signal received at the information input of the threshold device 5 (Fig. 3), then goes to the combined information inputs of the first and second sampling and storage devices 15 and 16 and the input of the comparator 20. The pulses arriving at the control input of the threshold device are then sent to the combined control the inputs of the sampling and storage devices 15 and 16. At the moments of their arrival with an interval equal to the set value of the change in the frequency of rotation of the impeller of the turbomachine, the sampling and storage devices 15 and 16 are stored and stored in the memory the previous value of the signal with the diagnostic frequency until the difference amplifier 17 calculates their difference. When self-oscillations occur, this difference reaches the value of the reference voltage of the comparator 18, which generates a signal when the specified value of the ratio of the signal change with the diagnostic frequency to the change in the impeller rotation frequency is reached. The comparator 20 generates an output signal when the signal with the diagnostic frequency reaches the limit value corresponding to the limit value of the voltage in the blade. The key 19 commutes to the output of the threshold device 5 one of the signals generated by the comparators 18 and 20.

Since the second inputs of the comparators 8, 18 and 20, to which the reference voltages are supplied, are inverting, then at their outputs when the input signals reach the reference voltages, high level signals are generated.

The invention allows to diagnose self-oscillation of the blades of a turbomachine in real time with the aim of timely detection and prevention of dangerous stresses in the blades of a turbomachine and can be used both during its experimental refinement and in operation.

Claims (3)

1. A device for diagnosing auto-oscillations of the impeller of a turbomachine, containing two tunable active band-pass filters, a coincidence circuit, the output of which through a matching amplifier is connected to an indicator, characterized in that a signal driver, first and second amplitude detectors, a threshold device and a comparator are inserted into it, the first input of the device is the information input of the first tunable active bandpass filter, the second input of the device is the input of the signal shaper, t they input device is an information input of the second tunable bandpass filter is active, the control inputs of the first and second active tunable bandpass filters are connected together and to a first output of the signal, the second output of which is connected to a control input of the threshold device; the output of the first tunable active bandpass filter through the first amplitude detector is connected to the information input of the threshold device, the output of which is connected to one of the inputs of the coincidence circuit; the output of the second tunable active band-pass filter through a second amplitude detector and a comparator connected in series to another input of the coincidence circuit; the second input of the comparator is connected to a reference voltage source, and the output of the device is connected to the output of the matching amplifier. 2. The device according to claim 1, characterized in that the signal shaper comprises a pulse shaper, a pulse counter, a read-only memory and a digital-to-analog converter, the output of which is the first output of the signal shaper, the second output of which is connected to the pulse counter output, and the shaper input signal is connected to the input of the pulse shaper. 3. The device according to claim 1, characterized in that the threshold device contains the first and second sampling-storage devices, the outputs of which are connected to the inputs of a difference amplifier, the output of which through the first comparator is connected to one of the key inputs, the output of the second is connected to the other input comparator, the key output is the output of the threshold device; the information inputs of the sampling-storage devices and the input of the second comparator are interconnected with the information input of the threshold device, the control inputs of the sampling-storage devices are interconnected with the control input of the threshold device, the second inputs of the comparators are connected to voltage reference sources.

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