CN112462358B - Method and device for improving rotor and stator axial clearance measurement precision - Google Patents
Method and device for improving rotor and stator axial clearance measurement precision Download PDFInfo
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Abstract
The invention belongs to the field of non-contact distance measurement, and aims to improve the measurement precision of the rotor-stator axial gap when the length of a radio frequency transmission cable changes and the ambient temperature rises. The invention adopts the technical scheme that the device and the method for improving the rotor and stator axial clearance measurement precision comprise a microwave signal generating module, a signal power amplifying module, a signal receiving and mixing module, a signal conditioning and collecting module, a computer, a carrier circuit circulator, a reference circuit circulator, a carrier circuit radio frequency cable, a reference circuit radio frequency cable, a microwave carrier sensor and a microwave reference sensor, and the axial clearance measurement is realized by utilizing a same-frequency interference signal suppression model based on an amplitude-phase imbalance correction factor and a determination method of phase delay on the radio frequency cable by means of the device. The invention is mainly applied to non-contact distance measurement occasions.
Description
Technical Field
The invention belongs to the field of non-contact distance measurement. Specifically, the invention relates to an on-line measuring method and device for rotor and stator axial clearance, in particular to a method and device for improving rotor and stator axial clearance measuring accuracy by adopting a microwave double-path reference structure.
Background
Modern aircraft engines are developing towards high thrust-weight ratio, high supercharging ratio and high pre-vortex temperature, on one hand, the aircraft engines are influenced by rotation speed change, temperature load and pneumatic load, a rotating shaft deforms under load, a casing deforms, the rotating shaft and the casing are inconsistent in thermal expansion, an excessively small axial gap can increase shaft work, the efficiency is reduced, the through-flow capacity is reduced, the pneumatic performance is deteriorated, and even a rotor and a stator are subjected to collision and abrasion, so that the safety and the reliability of the engines are influenced; on the other hand, the design of reducing the axial clearance is beneficial to shortening the size of the engine, enables the engine stages to be more compact, reduces the weight of the engine and effectively improves the thrust-weight ratio. At present, the active clearance control technology of the aircraft engine becomes one of the marking technologies of the modern engine, the acquisition and analysis of the running state parameters of the aircraft engine are the basis for realizing the active clearance control, and the non-contact on-line monitoring of the rotor and stator clearances of the aircraft engine has very important significance.
At present, the relatively mature non-contact rotor and stator clearance measuring method mainly aims at blade tip clearance, a bench test is completed, related research results at home and abroad of axial clearance are few, a calculated value of an engine prototype is generally used as a standard during actual assembly, installation clearance errors and clearance errors exist, and a mature rotor and stator axial clearance online measuring system does not exist.
The rotor and stator axial clearance monitoring position of the aircraft engine is usually positioned in an outer bypass air cooling environment, the temperature of the rotor and stator axial clearance measuring position of a fan and an air compressor reaches 300 ℃, and the temperature of the rotor and stator axial clearance measuring position of a turbine reaches 450 ℃. In the traditional method for measuring the tiny clearance of the aero-engine, the optical method is easily influenced by environmental oil contamination, the measuring life is shortened, and the processing cost when the method is applied to a high-temperature (450 ℃) testing environment is very high; when the measuring range is 10mm, the diameter of the end surface of the probe reaches 60mm by a capacitance method, and the size of the sensor is too large, so that the method is not suitable for a measuring environment with very limited internal space of an aircraft engine; the eddy current method is only suitable for the working environment of the engine at normal temperature and low speed, and is not suitable for clearance measurement at high temperature; compared with other methods, the microwave method is not easily influenced by the internal working environment of the engine and is more suitable for measuring the tiny gap in the engine, but the strength and the phase of microwave transmitting and receiving signals are influenced by the high-temperature working environment, so that the measurement accuracy of the rotor-stator axial gap is reduced.
The microwave method can be divided into a reflection intensity method, a linear frequency modulation method and a phase difference method, the reflection intensity method is easily influenced by a stator shelter around a rotor piece and the temperature of a working environment, and the measurement precision cannot meet the measurement requirement; the linear frequency modulation method needs very high signal bandwidth to achieve higher measurement accuracy, but the structure is too complex; the phase difference method adopts orthogonal demodulation and low-pass filtering methods to realize rotor and stator axial gap measurement, but the measurement accuracy of the rotor and stator axial gap can be directly reduced by the length change of the radio frequency transmission cable and the drift of the phase delay amount of the radio frequency transmission cable when the environmental temperature rises.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method and a device for improving the measurement precision of the rotor-stator axial clearance, so that the measurement precision of the rotor-stator axial clearance is improved when the length of a radio frequency transmission cable is changed and the environmental temperature is increased. Therefore, the technical scheme adopted by the invention is that the device for improving the rotor-stator axial clearance measurement precision comprises a microwave signal generation module, a signal power amplification module, a signal receiving and mixing module, a signal conditioning and collecting module, a computer, a carrier circuit circulator, a reference circuit circulator, a carrier circuit radio frequency cable, a reference circuit radio frequency cable, a microwave carrier sensor and a microwave reference sensor;
the signal receiving and frequency mixing module consists of a carrier wave way frequency mixer and a first reference way frequency mixer and a second reference way frequency mixer;
the microwave signal generating module generates a carrier signal and a reference signal, the carrier signal is transmitted to a microwave carrier sensor through a signal power amplifying module, a carrier circuit circulator and a carrier circuit radio frequency cable in sequence, the microwave carrier sensor transmits the carrier signal to the axial end face of the measured rotor and receives a carrier reflection signal of the axial end face of the rotor, and the received carrier reflection signal is used as a radio frequency input signal of the carrier circuit mixer after passing through the carrier circuit radio frequency cable for receiving and the carrier circuit circulator; the reference signal is amplified by the signal power amplification module and then is used as a local oscillation input signal of the carrier wave circuit frequency mixer; the carrier way mixer outputs two paths of orthogonal demodulation signals, and the two paths of orthogonal demodulation signals are transmitted to a computer after being preprocessed by a signal conditioning and collecting module;
the reference signal generated by the microwave signal generation module is transmitted to the end face of the microwave reference sensor through the signal power amplification module, the reference circuit circulator and the reference circuit radio frequency cable in sequence to be reflected and returned, and the returned signal is transmitted to the reference circuit circulator through the reference circuit radio frequency cable for receiving and then is output and used as a local oscillation input signal of the first reference circuit frequency mixer; a carrier signal generated by the microwave signal generation module is amplified and then is used as a radio frequency input signal of the first reference path mixer; the first reference path mixer outputs two paths of orthogonal demodulation signals, and the two paths of orthogonal demodulation signals are transmitted to a computer after being preprocessed by a signal conditioning and collecting module;
a carrier signal generated by the microwave signal generation module passes through the signal power amplification module to be used as a radio frequency input signal of a second reference path mixer; amplifying the reference signal generated by the microwave signal generation module to be used as a local oscillator input signal of the second path of reference path frequency mixer; the second reference path mixer outputs one path of orthogonal demodulation signal, and the orthogonal demodulation signal is transmitted to the computer after being preprocessed by the signal conditioning acquisition module;
and the computer processes the input signal to obtain the rotor and stator axial clearance.
The microwave signal generating module includes: the system comprises a clock reference, a controller, a carrier circuit phase-locked loop, a carrier circuit voltage-controlled oscillator, a carrier circuit loop filter, a reference circuit phase-locked loop, a reference circuit voltage-controlled oscillator and a reference circuit loop filter;
the signal power amplification module includes: a carrier wave way power amplifier, a carrier wave way medium power amplifier, a reference way medium power amplifier and a reference way power amplifier;
the signal receiving and mixing module comprises: a reference path mixer, a reference path radio frequency low noise amplifier, a first low pass filter (17), a second low pass filter (18), a reference path mixer, a third low pass filter (20), a fourth low pass filter (21), a fifth low pass filter (22), a carrier path mixer and a carrier path radio frequency low noise amplifier;
the clock reference provides a stable frequency reference for the system;
the controller sets the carrier wave path phase-locked loop to work at carrier frequency omegarIn the mode; the carrier wave path phase-locked loop outputs pulse current signal through internal charge pumpAfter the carrier circuit loop filter is subjected to band-pass filtering, the carrier circuit voltage-controlled oscillator outputs carrier frequency omegarSimultaneously, the phase difference between a frequency multiplication signal of the clock reference and a carrier feedback signal of the carrier circuit voltage-controlled oscillator is monitored in real time through an internal phase discriminator, and the phase difference between the two signals is zero;
after the power of a carrier circuit power amplifier is amplified, a carrier signal output by the carrier circuit voltage-controlled oscillator enters a first port of the carrier circuit circulator and is output from a second port of the carrier circuit circulator; the second port of the carrier wave circulator is connected with a carrier wave radio frequency cable, the carrier wave radio frequency cable is connected with a microwave carrier sensor, the microwave carrier sensor transmits a carrier signal to the axial end face of the measured rotor, receives a carrier reflection signal of the axial end face of the rotor at the same time, and the carrier reflection signal is transmitted back to the second port of the carrier wave circulator through the carrier wave radio frequency cable and is output from the third port of the carrier wave circulator;
the controller sets the phase-locked loop of the reference path to work at the reference frequency omegasIn the mode; the reference circuit phase-locked loop outputs a pulse current signal through an internal charge pump, and after the pulse current signal is subjected to band-pass filtering through a reference circuit loop filter, the reference circuit voltage-controlled oscillator outputs a reference frequency omegasSimultaneously, the phase difference between a frequency multiplication signal of a clock reference and a reference feedback signal of a reference circuit voltage-controlled oscillator is monitored in real time through an internal phase discriminator, and the phase difference between the two signals is zero;
a reference signal output by the reference circuit voltage-controlled oscillator enters a first port of the reference circuit circulator after being amplified by the power of the reference circuit power amplifier and is output from a second port of the reference circuit circulator; and a second port of the reference path circulator is connected with a reference path radio frequency line, a reference path radio frequency cable is connected with a reference path microwave reference sensor, and a reference signal transmitted by the reference path microwave reference sensor is totally reflected on the end surface of the sensor, passes through the reference path radio frequency cable, is input back to the second port of the reference path circulator and is output from a third port of the reference path circulator.
The reference path microwave reference sensor structure includes: the microwave antenna, the metal hollow sleeve and the metal reference reflecting end surface are arranged on the base; the metal reference reflecting end face is used as the end face of the reference path microwave reference sensor, and all reference signals transmitted by the reference path microwave reference sensor can be reflected back to the reference path radio frequency cable;
the gap value s between the microwave antenna and the metal reference reflecting end surface is millimeter-sized and is not zero;
the reference signal output by the third port of the reference path circulator is amplified by the reference path radio frequency low noise amplifier and then is used as the local oscillator input signal Y of the reference path frequency mixer2(ii) a Meanwhile, a carrier signal output by the carrier circuit voltage-controlled oscillator is amplified by the medium gain of the medium power amplifier in the carrier circuit and then is used as a radio frequency input signal X of the reference circuit frequency mixer1(ii) a The reference path mixer outputs two paths of orthogonal demodulation signals which are respectively subjected to a first low-pass filter (17) and a second low-pass filter (18) to form ZI1And ZQ1The two paths of signals are pre-processed by a signal conditioning and collecting module and then transmitted to a computer;
the carrier signal output by the third port of the carrier circuit circulator is amplified by the carrier circuit radio frequency low noise amplifier and then is used as the radio frequency input signal Y of the carrier circuit mixer1(ii) a Meanwhile, a reference signal output by the reference circuit voltage-controlled oscillator is amplified by the medium gain of the medium power amplifier in the reference circuit and then is used as a local oscillator input signal X of the carrier circuit frequency mixer2(ii) a The carrier way mixer outputs two paths of orthogonal demodulation signals which are respectively processed by a fourth low-pass filter (21) and a fifth low-pass filter (22) to be ZI2And ZQ2The two paths of signals are also transmitted to the computer after being preprocessed by the signal conditioning and collecting module;
the carrier signal output by the carrier circuit voltage-controlled oscillator is amplified by the medium gain of the medium power amplifier in the carrier circuit and then is used as the radio frequency input signal Y of the reference circuit frequency mixer3(ii) a Meanwhile, a reference signal output by the voltage-controlled oscillator of the reference path is amplified by the medium gain of the medium power amplifier of the reference path and then is used as a local oscillator input signal X of the frequency mixer of the reference path3(ii) a The reference path mixer outputs a path of orthogonal demodulation signal which is Z after passing through a third low-pass filter (20)I3And the signal is preprocessed by the signal conditioning and collecting module and then transmitted to the computer.
The signal conditioning and collecting module can be composed of a signal amplifying circuit, a signal filtering circuit and an analog-digital conversion circuit.
The method for improving the measurement accuracy of the rotor-stator axial clearance utilizes the realization of improving the measurement accuracy of the rotor-stator axial clearance, wherein, a microwave double-path reference structure and a carrier frequency omega of carrier path phase-locked loop work are adoptedrReference frequency omega for operating with reference path phase-locked loopsThe carrier wave path radio frequency cable and the reference path radio frequency cable are close to each other as much as possible, and the carrier wave path radio frequency cable and the reference path radio frequency cable are arranged side by side and tightly, so that radio frequency signal phase delay amount drifting values on the carrier wave path radio frequency cable and the reference path radio frequency cable caused by length change of the radio frequency cables or environmental temperature change in the working process of an aircraft engine are equal;
local oscillator input signal Y of input reference path frequency mixer2And a radio frequency input signal X1Can be represented by formula (1) and formula (2), respectively:
wherein A is1For the radio-frequency input signal X1Amplitude of (A)5For local oscillator input signal Y2Amplitude of the reflected portion of the end face of the medium microwave reference sensor, A6For local oscillator input signal Y2Amplitude, omega, of RF co-frequency crosstalk part caused by low isolation of RF chip or circulatorsAs reference frequency, ωrIs the carrier frequency and is,for the radio-frequency input signal X1The phase of (a) is determined,for local oscillator input signal Y2The end face reflection part of the medium microwave reference sensor delays the phase on the radio frequency cable of the reference path,for local oscillator input signal Y2The phase of the radio frequency co-frequency crosstalk part delayed on a transmission path due to low isolation of a radio frequency chip or a circulator;
two paths of orthogonal demodulation signals output by the reference path frequency mixer are respectively filtered by a first low-pass filter (17) and a second low-pass filter (18) to remove omega frequencyr+ωsAfter the frequency component of (2), the signal Z is obtainedI1And ZQ1Expressed by formulas (3) and (4), respectively:
wherein k' is a reference road amplitude imbalance factor,as a reference path phase imbalance factor, ωIF=ωs-ωrIs an intermediate frequency;
radio frequency input signal Y of input carrier circuit mixer1And local oscillator input signal X2Expressed by formula (5) and formula (6), respectively:
wherein A is2For local oscillator input signal X2Amplitude of (A)3For the radio-frequency input signal Y1Amplitude of the reflected signal portion of the intermediate carrier, A4For the radio-frequency input signal Y1Amplitude, omega, of RF co-frequency crosstalk part caused by low isolation of RF chip or circulatorsAs reference frequency, ωrIs the carrier frequency and is,for local oscillator input signal X2The phase of (a) is determined,for the radio-frequency input signal Y1The phase of the intermediate carrier reflected signal portion delayed on the carrier path radio frequency cable 29,for the radio-frequency input signal Y1Wherein the radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator delays the phase on the transmission path,for the radio-frequency input signal Y1The middle carrier reflected signal part is subjected to the phase to be detected generated by the change of the rotor stator axial gap;
two paths of orthogonal demodulation signals output by the carrier path mixer are respectively filtered by a fourth low-pass filter (21) and a fifth low-pass filter (22) to remove omega frequencyr+ωsAfter the frequency component of (2), the signal Z is obtainedI2And ZQ2And are represented by formula (7) and formula (8), respectively:
ZI2=SI_IF(t)+SI_le(t) (7)
ZQ2=SQ_IF(t)+SQ_le(t) (8)
is ZI2The radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator in the radio frequency co-frequency crosstalk part;
is ZQ2The radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator in the radio frequency co-frequency crosstalk part;
wherein k is the carrier path amplitude imbalance factor,is the carrier wave path phase unbalance factor;
further, the RF input signal Y is input to the reference mixer 193And local oscillator input signal X3Can be represented by formula (9) and formula 10, respectively:
wherein A is7For local oscillator input signal X3The amplitude of (a) of (b) is,for local oscillator input signal X3Phase of (A)8For the radio-frequency input signal Y3The amplitude of (a) of (b) is,for the radio-frequency input signal Y3The phase of (d);
one path of demodulated signal output by the reference path mixer 19 is filtered by a third low-pass filter (20) to remove the frequency omegar+ωsAfter the frequency component of (2), the signal Z is obtainedI3Represented by formula (11):
in the computer, for the reference path, the Z from the transmissionI1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'I(d) Is a reaction of ZQ1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'Q(d) (ii) a For carrier paths, Z from the transmissionI2And ZI3Performing mixing operation and low-pass filtering to obtain signal VI(d) Is a reaction of ZQ2And ZI3Performing mixing operation and low-pass filtering to obtain signal VQ(d);V'I(d)、V'Q(d)、VI(d) And VQ(d) Expressed by formulas (12), (13), (14) and (15), respectively:
in formulae (12), (13), (14) and (15), k'; and,Ale、A'leAre constant and do not vary with rotor-stator axial clearance, and AIFOnly the rotor and stator axial clearance is related, and the inverse proportion relation is formed by the second power of the rotor and stator axial clearance d; a'tip、The axial clearance of the rotor and the stator does not change along with the change of the axial clearance of the rotor and the stator, but drifts along with the change of the temperature of the working environment;
based on the microwave phase ranging principle:
wherein ω is1Is the spatial angular frequency of the transmitted microwave radio frequency signal;
from formulae (14), (15) and (16):
using the frequency spectrum of V (d) signal mainly at main frequency omega1Image frequency-omega1And the DC frequency, the amplitude values at the three frequencies are respectively A (omega) through space distance scanning, namely, rotor and stator axial gap sampling at equal intervals1)、A(-ω1) A (0); the amplitude-phase imbalance correction factor is expressed by equation (18), equation (19), equation (20), and equation (21):
the method adopts an improved co-channel interference signal suppression step based on spatial distance scanning, and a model for suppressing the co-channel interference signals of the carrier channel is shown as a formula (22):
therefore, the rotor-stator axial gap d after suppressing the carrier channel co-channel interference signal is expressed by equation (23):
wherein,the axial clearance of the rotor to be measured does not change, but drifts along with the temperature change of the working environment;
the determination method comprises the following steps: when the system is calibrated, the reference path radio frequency cable is not connected with the microwave reference sensor and is directly connected with the dummy load, so that the complete absorption of the reference signal is realized, and the formula (3) and the formula (4) are adopted) Formula (12) and formula (13) are represented by formula (24), formula (25), formula (26), and formula (27), respectively:
the following equations 24 and 25 can be obtained:
Z'1(t) signal at main frequency ωIFImage frequency-omegaIFThe amplitudes at these two frequencies are A (ω)IF)、A(-ωIF) (ii) a The amplitude-phase imbalance correction factor is expressed by equations (29) and (30):
the model for suppressing the co-channel interference signal of the reference channel is shown as formula (31):
thus, shootFrequency input signal Y2Phase of medium microwave reference sensor end face reflection part delayed on reference path radio frequency cableRepresented by formula (32):
radio frequency signal phase delay amount on carrier wave path radio frequency cable caused by environment temperature change in working process of aircraft engineAnd the phase delay of the RF signal on the RF cable 30 of the reference pathEqually, by equations (23) and (32), the real-time online high-precision measurement method of the rotor-stator axial gap d is represented by equation (33):
wherein c, f,The value is constant and does not change with the axial clearance of the rotor and the stator to be measured and the temperature change of the working environment, and the value is obtained by calibration.
The invention has the characteristics and beneficial effects that:
the method solves the problem that when the phase difference-based microwave type micro-gap measuring method is used for measuring the rotor-stator axial gap of an aircraft engine, the measurement accuracy of the rotor-stator axial gap can be directly reduced due to the length change of a radio frequency transmission cable and the drift of the phase delay of the radio frequency transmission cable when the ambient temperature rises. A method and a device for improving the measurement precision of the rotor and stator axial clearance are designed, a microwave double-channel reference structure is utilized, two carrier paths and a reference path transmission cable which are completely consistent in length and working performance are adopted, a carrier path probe and a reference path probe are close to each other as much as possible and are placed in the same working environment, an improved same-frequency interference signal suppression method based on spatial distance scanning is provided, and the measurement precision of the rotor and stator axial clearance of an aero-engine is improved under the condition that the phase delay of a radio frequency transmission cable is shifted due to the change of the length of the radio frequency transmission cable and the rise of the ambient temperature.
Description of the drawings:
fig. 1 is a schematic diagram of the method and apparatus for improving the measurement accuracy of rotor-stator axial clearance according to the present invention.
Fig. 2 shows a schematic diagram of the construction of the microwave reference sensor 32 of the present invention.
FIG. 3 is a schematic diagram showing the variation of the phase of the RF signal with the cable length or the variation of the environmental temperature when the axial gap of the stator to be tested is constant
In fig. 1: 1 is a clock reference, 2 is a controller, 3 is a carrier circuit phase-locked loop, 4 is a carrier circuit voltage-controlled oscillator, 5 is a carrier circuit loop filter, 6 is a reference circuit phase-locked loop, 7 is a reference circuit voltage-controlled oscillator, 8 is a reference circuit loop filter, 9 is a carrier circuit power amplifier, 10 is a carrier circuit medium power amplifier, 11 is a carrier circuit medium power amplifier, 12 is a reference circuit medium power amplifier, 13 is a reference circuit medium power amplifier, 14 is a reference circuit power amplifier, 15 is a reference circuit mixer, 16 is a reference circuit radio frequency low noise amplifier, 17 is a low pass filter, 18 is a low pass filter, 19 is a reference circuit mixer, 20 is a low pass filter, 21 is a low pass filter, 22 is a low pass filter, 23 is a carrier circuit mixer, 24 is a carrier circuit radio frequency low noise amplifier, 25 is a signal conditioning and collecting module, 26 is an upper computer, the device comprises a carrier circuit circulator 27, a reference circuit circulator 28, a carrier circuit radio-frequency cable 29, a reference circuit radio-frequency cable 30, a microwave carrier sensor 31, a microwave reference sensor 32, a rotor axial end face 33, a microwave signal generating module 34, a signal power amplifying module 35 and a signal receiving and mixing module 36.
In fig. 2: 234 is a microwave antenna, 235 is a metal hollow sleeve, 236 is a metal reference reflecting end face.
In fig. 3: 37 phase position after same frequency interference suppression of carrier path signalThe curve changing along with the length of the cable or the change of the environmental temperature and the phase of the reference path signal 38 after the same frequency interference is inhibitedThe curve 39, which varies with the cable length or with the ambient temperature, is the difference curve between the curves 37 and 38.
Detailed Description
In order to overcome the defects in the prior art, the invention designs a method and a device for improving the measurement precision of the axial clearance of a rotor and a stator, and mainly solves the technical problems that:
the method solves the problem that when the phase difference-based microwave type micro-gap measuring method is used for measuring the rotor-stator axial gap of an aircraft engine, the phase delay amount drift of a radio frequency transmission cable caused by the length change of the radio frequency transmission cable and the rise of the ambient temperature can directly reduce the rotor-stator axial gap measuring precision. A method and a device for improving the measurement precision of the rotor and stator axial clearance are designed, a microwave double-channel reference structure is utilized, two carrier paths and a reference path transmission cable which are completely consistent in length and working performance are adopted, a carrier path probe and a reference path probe are close to each other as much as possible and are placed in the same working environment, an improved same-frequency interference signal suppression method based on spatial distance scanning is provided, and the measurement precision of the rotor and stator axial clearance of an aero-engine is improved under the condition that the phase delay of a radio frequency transmission cable is shifted due to the change of the length of the radio frequency transmission cable and the rise of the ambient temperature.
In order to achieve the above objective, the present invention adopts a technical solution that a method and a device for improving the measurement accuracy of the rotor and stator axial clearance are designed, as shown in fig. 1, and mainly include: a microwave signal generating module 34, a signal power amplifying module 35, a signal receiving and mixing module 36, a signal conditioning and collecting module 25, an upper computer 26, a carrier circuit circulator 27, a reference circuit circulator 28, a carrier circuit radio frequency cable 29, a reference circuit radio frequency cable 30, a microwave carrier sensor 31 and a microwave reference sensor 32;
the microwave signal generating module 34 mainly includes: the system comprises a clock reference 1, a controller 2, a carrier circuit phase-locked loop 3, a carrier circuit voltage-controlled oscillator 4, a carrier circuit loop filter 5, a reference circuit phase-locked loop 6, a reference circuit voltage-controlled oscillator 7 and a reference circuit loop filter 8;
the signal power amplifying module 35 mainly includes: a carrier wave way power amplifier 9, a carrier wave way medium power amplifier 10, a carrier wave way medium power amplifier 11, a reference way medium power amplifier 12, a reference way medium power amplifier 13 and a reference way power amplifier 14;
the signal receiving and mixing module 36 mainly includes: a reference path mixer 15, a reference path radio frequency low noise amplifier 16, a low pass filter 17, a low pass filter 18, a reference path mixer 19, a low pass filter 20, a low pass filter 21, a low pass filter 22, a carrier path mixer 23, and a carrier path radio frequency low noise amplifier 24;
further, a device for improving the measurement precision of the rotor and stator axial clearance is a coherent measurement system, and a clock reference 1 provides stable frequency reference for the system;
further, the controller 2 sets the carrier phase-locked loop 3 to operate at the carrier frequency ωrIn the mode; the carrier wave circuit phase-locked loop 3 outputs a pulse current signal through an internal charge pump, and after the pulse current signal is subjected to band-pass filtering through the carrier wave circuit loop filter 5, the carrier wave circuit voltage-controlled oscillator 4 outputs carrier frequency omegarSimultaneously, the phase difference between the frequency multiplication signal of the clock reference 1 and the carrier feedback signal of the carrier circuit voltage-controlled oscillator 4 is monitored in real time through an internal phase discriminator, and the phase difference between the two signals is zero;
further, the carrier signal output by the carrier circuit voltage-controlled oscillator 4 enters the first port of the carrier circuit circulator 27 after being power-amplified by the carrier circuit power amplifier 9, and is output from the second port of the carrier circuit circulator 27 with a smaller insertion loss; the second port of the carrier wave loop 27 is connected with the carrier wave radio frequency cable 29, the carrier wave radio frequency cable 29 is connected with the microwave carrier sensor 31, the microwave carrier sensor 31 transmits a carrier signal to the axial end face 33 of the measured rotor, receives a carrier reflection signal of the axial end face 33 of the rotor, outputs the carrier wave signal to the second port of the carrier wave loop 27 through the carrier wave radio frequency cable 29, and outputs the carrier wave signal from the third port of the carrier wave loop 27 with smaller insertion loss;
further, the controller 2 sets the reference phase-locked loop 6 to operate at the reference frequency ωsIn the mode; the reference circuit phase-locked loop 6 outputs a pulse current signal through an internal charge pump, and after the pulse current signal is subjected to band-pass filtering through a reference circuit loop filter 8, the reference circuit voltage-controlled oscillator 7 outputs a reference frequency omegasSimultaneously, the phase difference between the frequency multiplication signal of the clock reference 1 and the reference feedback signal of the reference circuit voltage-controlled oscillator 7 is monitored in real time through an internal phase discriminator, and the phase difference between the two signals is zero;
further, the reference signal output by the reference path voltage-controlled oscillator 7 enters a first port of the reference path circulator 28 after being power-amplified by the reference path power amplifier 14, and is output from a second port of the reference path circulator 28 with a smaller insertion loss; the second port of the reference path circulator 28 is connected with a reference path radio frequency cable 30, the reference path radio frequency cable 30 is connected with a microwave reference sensor 32, a reference signal emitted by the microwave reference sensor 32 is totally reflected on the end face of the sensor, passes through the reference path radio frequency cable 30, is input back to the second port of the reference path circulator 28, and is output from the third port of the reference path circulator 28 with smaller insertion loss;
further, the structure of the microwave reference sensor 32 is shown in fig. 2, and mainly includes: a microwave antenna 34, a metal hollow sleeve 35, a metal reference reflecting end face 36; the metal reference reflecting end face 36 serves as an end face of the microwave reference sensor 32, and can reflect all reference signals emitted by the microwave reference sensor 32 back to the reference circuit radio frequency cable 30;
further, the gap s between the microwave antenna 34 and the metal reference reflecting end face 36 is in millimeter level and is not zero;
further, the reference signal outputted from the third port of the reference loop circulator 28 is amplified by the reference loop rf low noise amplifier 16Local oscillator input signal Y of frequency mixer 15 as reference path2(ii) a Meanwhile, the carrier signal output by the carrier circuit voltage-controlled oscillator 4 is amplified by the medium gain of the carrier circuit medium power amplifier 10 and then used as the radio frequency input signal X of the reference circuit mixer 151(ii) a The reference path mixer 15 outputs two paths of orthogonal demodulation signals which are respectively processed by low pass filters 17 and 18 to be ZI1And ZQ1The two paths of signals are preprocessed by the signal conditioning and collecting module 25 and then transmitted to the upper computer 26;
further, the carrier signal output from the third port of the carrier loop 27 is amplified by the carrier rf low-noise amplifier 24 and then used as the rf input signal Y of the carrier mixer 231(ii) a Meanwhile, the reference signal output by the reference circuit voltage-controlled oscillator 7 is amplified by the medium gain of the medium power amplifier 13 in the reference circuit and then is used as the local oscillator input signal X of the carrier circuit mixer 232(ii) a The carrier mixer 23 outputs two orthogonal demodulation signals, which are respectively passed through low-pass filters 21 and 22 and are ZI2And ZQ2The two paths of signals are also preprocessed by the signal conditioning and collecting module 25 and then transmitted to the upper computer 26;
furthermore, the carrier signal output by the carrier circuit voltage-controlled oscillator 4 is amplified by the medium gain of the carrier circuit medium power amplifier 11 and then used as the radio frequency input signal Y of the reference circuit mixer 193(ii) a Meanwhile, a reference signal output by the reference circuit voltage-controlled oscillator 7 is amplified by the medium gain of the reference circuit medium power amplifier 12 and then is used as a local oscillator input signal X of the reference circuit mixer 193(ii) a The reference channel mixer 19 outputs a quadrature demodulation signal, which is Z after passing through the low pass filter 20I3The signal is preprocessed by the signal conditioning and collecting module 25 and then transmitted to the upper computer 26;
further, in the present invention, the signal conditioning and collecting module 25 may be composed of a signal amplifying circuit, a signal filtering circuit and an analog-digital converting circuit;
furthermore, the invention adopts a microwave double-path reference structure, and the carrier frequency omega of the carrier path phase-locked loop 3 workrAnd a reference frequency omega at which the reference phase-locked loop 6 operatessNeed to be connected as much as possibleIn the near, the carrier way radio frequency cable 29 and the reference way radio frequency cable 30 use radio frequency cables with the same length and model and are closely arranged side by side, so that the radio frequency signal phase delay amount drift values on the carrier way radio frequency cable 29 and the reference way radio frequency cable 30 caused by the length change of the radio frequency cables or the change of the environmental temperature in the working process of an aircraft engine are equal, when the phase difference between the carrier way and the reference way is calculated, the phase measurement error caused by the change of the environmental temperature can be inhibited, and the measurement precision of the rotor stator axial gap is improved;
further, the local oscillation input signal Y of the reference path mixer 15 is inputted2And a radio frequency input signal X1May be represented by formula 1 and formula 2, respectively:
wherein A is1For the radio-frequency input signal X1Amplitude of (A)5For local oscillator input signal Y2Amplitude, A, of the end-face reflection of the medium microwave reference sensor 326For local oscillator input signal Y2Amplitude, omega, of RF co-frequency crosstalk part caused by low isolation of RF chip or circulatorsAs reference frequency, ωrIs the carrier frequency and is,for the radio-frequency input signal X1The phase of (a) is determined,for local oscillator input signal Y2The reflected part of the end face of the middle microwave reference sensor 32 has delayed phase on the reference path radio frequency cable 30,for local oscillator input signal Y2The phase of the radio frequency co-frequency crosstalk part delayed on a transmission path due to low isolation of a radio frequency chip or a circulator;
two paths of orthogonal demodulation signals output by the reference path mixer 15 are respectively filtered by a low pass filter 17 and a low pass filter 18 to remove the frequency omegar+ωsAfter the frequency component of (2), the signal Z is obtainedI1And ZQ1And can be represented by formula 3 and formula 4, respectively:
wherein k' is a reference road amplitude imbalance factor,as a reference path phase imbalance factor, ωIF=ωs-ωrIs an intermediate frequency;
further, a radio frequency input signal Y is input to the carrier circuit mixer 231And local oscillator input signal X2May be represented by formulas 5 and 6, respectively:
wherein A is2For local oscillator input signal X2Amplitude of (A)3For the radio-frequency input signal Y1Amplitude of the reflected signal portion of the intermediate carrier, A4For the radio-frequency input signal Y1Amplitude, omega, of RF co-frequency crosstalk part caused by low isolation of RF chip or circulatorsAs reference frequency, ωrIs the carrier frequency and is,for local oscillator input signal X2The phase of (a) is determined,for the radio-frequency input signal Y1The phase of the intermediate carrier reflected signal portion delayed on the carrier path radio frequency cable 29,for the radio-frequency input signal Y1Wherein the radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator delays the phase on the transmission path,for the radio-frequency input signal Y1The middle carrier reflected signal part is subjected to the phase to be detected generated by the change of the rotor stator axial gap;
two paths of orthogonal demodulation signals output by the carrier path mixer 23 are respectively filtered by the low-pass filter 21 and the low-pass filter 22 to remove the frequency omegar+ωsAfter the frequency component of (2), the signal Z is obtainedI2And ZQ2And can be represented by formula 7 and formula 8, respectively:
ZI2=SI_IF(t)+SI_le(t) (7)
ZQ2=SQ_IF(t)+SQ_le(t) (8)
is ZI2The radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator in the radio frequency co-frequency crosstalk part;
is ZQ2The radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator in the radio frequency co-frequency crosstalk part;
wherein k is the carrier path amplitude imbalance factor,is the carrier wave path phase unbalance factor;
further, the RF input signal Y is input to the reference mixer 193And local oscillator input signal X3May be represented by formulas 9 and 10, respectively:
wherein A is7For local oscillator input signal X3The amplitude of (a) of (b) is,for local oscillator input signal X3Phase of (A)8For the radio-frequency input signal Y3The amplitude of (a) of (b) is,for the radio-frequency input signal Y3The phase of (d);
one path of demodulated signal output by the reference path mixer 19 is filtered by the low pass filter 20 to remove the frequency omegar+ωsAfter the frequency component of (2), the signal Z is obtainedI3And can be represented by formula 11:
further, in the upper computer 26, for the reference path, the Z coming from the transmission will be transmittedI1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'I(d) Is a reaction of ZQ1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'Q(d) (ii) a For carrier paths, Z from the transmissionI2And ZI3Performing mixing operation and low-pass filtering to obtain signal VI(d) Is a reaction of ZQ2And ZI3Performing mixing operation and low-pass filtering to obtain signal VQ(d);V'I(d)、V'Q(d)、VI(d) And VQ(d) Can be represented by formulas 12, 13, 14 and 15, respectively:
in formulae 12, 13, 14 and 15, k'),Ale、A'leAre constant and do not vary with rotor-stator axial clearance, and AIFOnly the rotor and stator axial clearance is related, and the inverse proportion relation is formed by the second power of the rotor and stator axial clearance d; a'tip、The axial clearance of the rotor and the stator does not change along with the change of the axial clearance of the rotor and the stator, but drifts along with the change of the temperature of the working environment;
further, based on the principle of microwave phase distance measurement, the method comprises
Wherein ω is1Is the spatial angular frequency of the transmitted microwave radio frequency signal;
the following equations 14, 15 and 16 can be obtained:
furthermore, the invention utilizes the V (d) signal frequency spectrum to be mainly at the main frequency omega1Image frequency-omega1And the DC frequency, the amplitude values at the three frequencies are respectively A (omega) through space distance scanning, namely, rotor and stator axial gap sampling at equal intervals1)、A(-ω1) A (0); the amplitude-phase imbalance correction factor can be expressed by equation 18, equation 19, equation 20, and equation 21:
further, the invention provides an improved co-frequency interference signal suppression method based on spatial distance scanning, which utilizes a co-frequency interference signal suppression model based on an amplitude-phase imbalance correction factor and a determination method of phase delay amount on a radio frequency cable to suppress co-frequency interference from crosstalk of a transmitting end to a receiving end caused by low isolation of a radio frequency chip or a circulator under the condition that the length of the radio frequency transmission cable changes and the environmental temperature rises to cause phase delay amount drift of the radio frequency transmission cable;
the model for suppressing the co-channel interference signals of the carrier channel is shown as formula 22:
therefore, the rotor-stator axial gap d after suppressing the co-channel interference signal on the carrier path can be represented by equation 23:
wherein,the axial clearance of the rotor to be measured does not change, but drifts along with the temperature change of the working environment;
further, in the present invention,the determination method comprises the following steps: during system calibration, the reference path RF cable 30 is not connected to the microwave reference sensor 32, but is directly connected to the dummy loadAnd complete absorption of the reference signal is achieved, when equations 3, 4, 12, and 13 can be expressed as equations 24, 25, 26, and 27, respectively:
the following equations 24 and 25 can be obtained:
Z'1(t) signal at main frequency ωIFImage frequency-omegaIFThe amplitudes at these two frequencies are A (ω)IF)、A(-ωIF) (ii) a The correction factor for the amplitude-phase imbalance can be expressed by equations 29 and 30:
the model for suppressing the co-channel interference signal of the reference channel is shown as formula 31:
thus, the radio frequency input signal Y2The phase of the end face reflection part of the medium microwave reference sensor 32 delayed on the reference path radio frequency cable 30Can be represented by equation 32:
furthermore, in the invention, the phase delay of the radio frequency signal on the carrier wave path radio frequency cable 29 caused by the change of the environmental temperature in the working process of the aircraft engineAnd the phase delay of the RF signal on the RF cable 30 of the reference pathEqually, from equations 23 and 32, the real-time online high-precision measurement method of the rotor-stator axial gap d can be represented by equation 33:
wherein c, f,The value is constant, and the value does not change along with the axial clearance of the rotor and the stator to be measured and the temperature change of the working environment, and can be obtained by calibration.
Further, fig. 3 is a schematic diagram of the phase of the radio frequency signal changing with the length of the cable or the environmental temperature when the axial gap value of the rotor and stator to be measured is constant, where 37 is the phase of the carrier path signal after the same frequency interference is suppressedAccording to the curve of the change of the length of the cable or the change of the environmental temperature, 38 is used as a reference path signal for inhibiting same frequency interferencePhase after disturbanceThe curve along with the change of the cable length or the change of the environmental temperature 39 is the difference curve of the curve 37 and the curve 38, which shows that the method and the device for improving the axial clearance measurement accuracy of the rotor and the stator provided by the invention utilize the phase delay of the radio frequency signal on the carrier wave path radio frequency cable 29And the phase delay of the RF signal on the RF cable 30 of the reference pathUnder the same condition, the problem of the phase delay amount drift of the measurement signal caused by the change of the length of the cable or the change of the environmental temperature is solved, so that the rotor-stator axial gap d with high precision can be obtained by the formula 33.
In order to overcome the defects in the prior art, the invention designs a method and a device for improving the measurement precision of the axial clearance of a rotor and a stator, and mainly solves the technical problems that:
the method solves the problem that when the phase difference-based microwave type micro-gap measurement method is used for measuring the rotor-stator axial gap of an aircraft engine, the measurement accuracy of the rotor-stator axial gap can be directly reduced due to the drift of the phase delay amount of the radio frequency transmission cable caused by the length change of the radio frequency transmission cable and the rise of the ambient temperature. A method and a device for improving the measurement precision of the rotor and stator axial clearance are designed, a microwave double-channel reference structure is utilized, two carrier paths and a reference path transmission cable which are completely consistent in length and working performance are adopted, a carrier path probe and a reference path probe are close to each other as much as possible and are placed in the same working environment, an improved same-frequency interference signal suppression method based on spatial distance scanning is provided, and the measurement precision of the rotor and stator axial clearance of an aero-engine is improved under the condition that the phase delay of a radio frequency transmission cable is shifted due to the change of the length of the radio frequency transmission cable and the change of the environmental temperature.
The invention is realized by the following steps:
the invention designs a method and a device for improving the measurement precision of the rotor and stator axial clearance, as shown in figure 1, the method mainly comprises the following steps: clock reference 1, controller 2, carrier circuit phase-locked loop 3, carrier circuit voltage-controlled oscillator 4, carrier circuit loop filter 5, reference circuit phase-locked loop 6, reference circuit voltage-controlled oscillator 7, reference circuit loop filter 8, carrier circuit power amplifier 9, carrier circuit medium power amplifier 10, carrier circuit medium power amplifier 11, reference circuit medium power amplifier 12, reference circuit medium power amplifier 13, reference circuit power amplifier 14, reference circuit mixer 15, reference circuit radio frequency low noise amplifier 16, low pass filter 17, low pass filter 18, reference circuit mixer 19, low pass filter 20, low pass filter 21, low pass filter 22, carrier circuit mixer 23, carrier circuit radio frequency low noise amplifier 24, signal conditioning acquisition module 25, upper computer 26, carrier circuit circulator 27, reference circuit circulator 28, carrier circuit radio frequency cable 29, A reference path radio frequency cable 30, a microwave carrier sensor 31 and a microwave reference sensor 32; by adopting a microwave double-path reference structure and an improved co-channel interference signal suppression method based on spatial distance scanning, the non-contact real-time online high-precision measurement of the axial gap of the rotor and the stator of the aircraft engine is realized under the condition that the length of a radio frequency transmission cable changes and the phase delay amount of the radio frequency transmission cable is deviated due to the change of the environmental temperature.
The invention is further described with reference to the following figures and examples.
Further, in the invention, a device for improving the rotor and stator axial clearance measurement precision is a coherent measurement system, the clock reference 1 provides a stable frequency reference for the system, and an analog temperature compensation crystal oscillator, a digital temperature compensation crystal oscillator and the like with high frequency stability can be selected;
further, in the invention, the controller 2 sets the carrier wave path phase-locked loop 3 to work under the carrier frequency; the carrier circuit phase-locked loop 3 outputs a pulse current signal through an internal charge pump, the pulse current signal is subjected to band-pass filtering through a carrier circuit loop filter 5, a carrier circuit voltage-controlled oscillator 4 outputs a carrier signal, and meanwhile, the phase difference between a frequency multiplication signal of a clock reference 1 and a carrier feedback signal of the carrier circuit voltage-controlled oscillator 4 is monitored in real time through an internal phase discriminator and is enabled to be zero;
further, in the invention, the controller 2 can be a single chip microcomputer, an advanced reduced instruction set machine (ARM) and the like;
further, in the invention, the carrier wave path phase-locked loop 3 can be selected from an analog phase-locked loop, a digital phase-locked loop and the like;
further, in the present invention, the carrier circuit loop filter 5 may be a passive filter, an active filter, or the like;
further, in the present invention, the carrier signal output by the carrier circuit voltage-controlled oscillator 4 enters the first port of the carrier circuit circulator 27 after being power-amplified by the carrier circuit power amplifier 9, and is output from the second port of the carrier circuit circulator 27 with a smaller insertion loss; the second port of the carrier wave loop 27 is connected with the carrier wave radio frequency cable 29, the carrier wave radio frequency cable 29 is connected with the microwave carrier sensor 31, the microwave sensor 31 transmits a carrier signal to the axial end face 33 of the measured rotor, receives a carrier reflection signal of the axial end face 33 of the rotor, outputs the carrier wave signal to the second port of the carrier wave loop 27 through the carrier wave radio frequency cable 29, and outputs the carrier wave signal from the third port of the carrier wave loop 27 with smaller insertion loss;
further, in the present invention, the carrier path circulator 27 may be selected from a surface mount circulator, a wired circulator, a coaxial circulator, and the like;
further, in the present invention, the microwave carrier sensor 31 can be selected from a microwave resonant cavity structure, a microstrip antenna structure, a planar inverted F structure, etc.;
further, in the invention, the controller 2 sets the reference path phase-locked loop 6 to work under the reference frequency; the reference path phase-locked loop 6 outputs a pulse current signal through an internal charge pump, after the pulse current signal is subjected to band-pass filtering through a reference path loop filter 8, the reference path voltage-controlled oscillator 7 outputs a reference signal, and simultaneously, through an internal phase discriminator, the phase difference between a frequency multiplication signal of the clock reference 1 and a reference feedback signal of the reference path voltage-controlled oscillator 7 is monitored in real time and is enabled to be zero;
further, in the invention, the reference phase-locked loop 6 can be selected from an analog phase-locked loop, a digital phase-locked loop and the like;
further, in the present invention, the reference loop filter 8 may be a passive filter, an active filter, or the like;
further, in the present invention, the reference signal output by the reference path voltage-controlled oscillator 7 enters the first port of the reference path circulator 28 after being power-amplified by the reference path power amplifier 14, and is output from the second port of the reference path circulator 28 with a smaller insertion loss; the second port of the reference path circulator 28 is connected with a reference path radio frequency cable 30, the reference path radio frequency cable 30 is connected with a microwave reference sensor 32, a reference signal emitted by the microwave reference sensor 32 is totally reflected on the end face of the sensor, passes through the reference path radio frequency cable 30, is input back to the second port of the reference path circulator 28, and is output from the third port of the reference path circulator 28 with smaller insertion loss;
further, in the present invention, the reference road circulator 28 may be selected from a surface mount circulator, a wired circulator, a coaxial circulator, and the like;
further, in the present invention, the structure of the microwave reference sensor 32 is shown in fig. 2, and mainly includes: a microwave antenna 34, a metal hollow sleeve 35, a metal reference reflecting end face 36; the microwave antenna 34 may be a microwave resonant cavity structure, a microstrip antenna structure, a planar inverted-F structure, or the like; the metal reference reflecting end surface 36 is used as the end surface of the sensor, and can reflect all the reference signals emitted by the microwave sensor 32 back to the reference circuit radio frequency cable 30;
further, the gap s between the microwave antenna 34 and the metal reference reflecting end face 36 is in millimeter level and is not zero, such as 0.5 mm;
further, in the present invention, the carrier signal output from the third port of the reference loop circulator 28 is amplified by the reference loop radio frequency low noise amplifier 16 and then used as the local oscillator input signal of the reference loop mixer 15; meanwhile, a reference signal output by the carrier circuit voltage-controlled oscillator 4 is amplified by the medium gain of the carrier circuit medium power amplifier 10 and then is used as a radio frequency input signal of the reference circuit mixer 15; the reference path mixer 15 outputs two paths of orthogonal demodulation signals which are respectively processed by low pass filters 17 and 18 to be ZI1And ZQ1The two paths of signals are acquired by signal conditioningAfter being preprocessed by the module 25, the data is transmitted to an upper computer 26;
further, the carrier signal output from the third port of the carrier loop circulator 27 is amplified by the carrier loop radio frequency low noise amplifier 24 and then used as the radio frequency input signal of the carrier loop mixer 23; meanwhile, a reference signal output by the reference path voltage-controlled oscillator 7 is amplified by the medium gain of the medium power amplifier 13 in the reference path and then is used as a local oscillator input signal of the carrier path mixer 23; the carrier mixer 23 outputs two orthogonal demodulation signals, which are respectively passed through low-pass filters 21 and 22 and are ZI2And ZQ2The two paths of signals are also preprocessed by the signal conditioning and collecting module 25 and then transmitted to the upper computer 26;
further, a carrier signal output by the carrier circuit voltage-controlled oscillator 4 is amplified by the medium gain of the medium power amplifier 11 in the carrier circuit and then is used as a radio frequency input signal of the reference circuit mixer 19; meanwhile, a reference signal output by the reference path voltage-controlled oscillator 7 is amplified by the medium gain of the reference path medium power amplifier 13 and then is used as a local oscillator input signal of the reference path frequency mixer 19; the reference channel mixer 19 outputs a quadrature demodulation signal, which is Z after passing through the low pass filter 20I3The signal is preprocessed by the signal conditioning and collecting module 25 and then transmitted to the upper computer 26;
further, in the present invention, the signal conditioning and collecting module 25 may be composed of a signal amplifying circuit, a signal filtering circuit and an analog-digital converting circuit;
further, in the present invention, the upper computer 20 may adopt an industrial control computer, a general personal computer, or the like;
further, in the present invention, in the upper computer 20, for the reference path, the Z coming from the upper computer will be transmittedI1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'I(d) Is a reaction of ZQ1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'Q(d) (ii) a For carrier paths, Z from the transmissionI2And ZI3Performing mixing operation and low-pass filtering to obtain signal VI(d) Is a reaction of ZQ2And ZI3Performing mixing operation and low-pass filtering to obtainTo signal VQ(d);
Further, the invention provides an improved co-frequency interference signal suppression method based on spatial distance scanning, which utilizes a co-frequency interference signal suppression model based on an amplitude-phase imbalance correction factor and a determination method of phase delay amount on a radio frequency cable to suppress co-frequency interference from crosstalk of a transmitting end to a receiving end caused by low isolation of a radio frequency chip or a circulator under the condition that the phase delay amount of the radio frequency transmission cable drifts due to the length change of the radio frequency transmission cable and the change of environmental temperature; the model for suppressing the co-channel interference signals of the carrier channels is shown in the foregoing formula 22; the model for suppressing the co-channel interference signals of the reference channel is shown as the formula 31; the method for determining the phase delay on the rf cable is shown in equation 32;
further, fig. 3 is a schematic diagram of the phase of the radio frequency signal changing with the length of the cable or the environmental temperature when the axial gap value of the rotor and stator to be measured is constant, where 37 is the phase of the carrier path signal after the same frequency interference is suppressedThe curve changed along with the length of the cable or the change of the environmental temperature 38 is the phase of the reference path signal after the same frequency interference is inhibitedThe curve along with the change of the cable length or the change of the environmental temperature 39 is the difference curve of the curve 37 and the curve 38, which shows that the method and the device for improving the axial clearance measurement accuracy of the rotor and the stator provided by the invention utilize the phase delay of the radio frequency signal on the carrier wave path radio frequency cable 29And the phase delay of the RF signal on the RF cable 30 of the reference pathThe equal conditions solve the problem of phase delay amount drift of the measurement signal caused by cable length change or environmental temperature change;
further, in the present invention, a real-time on-line high-precision measurement method of the rotor-stator axial gap d can be represented by the foregoing formula 33.
Claims (1)
1. A device for improving the rotor and stator axial clearance measurement precision is characterized by comprising a microwave signal generating module, a signal power amplifying module, a signal receiving and mixing module, a signal conditioning and collecting module, a computer, a carrier circuit circulator, a reference circuit circulator, a carrier circuit radio frequency cable, a reference circuit radio frequency cable, a microwave carrier sensor and a microwave reference sensor;
the signal receiving and mixing module consists of a carrier path mixer and two reference path mixers;
the microwave signal generating module generates a carrier signal and a reference signal, the carrier signal is transmitted to a microwave carrier sensor through a signal power amplifying module, a carrier circuit circulator and a carrier circuit radio frequency cable in sequence, the microwave carrier sensor transmits the carrier signal to the axial end face of the measured rotor and receives a carrier reflection signal of the axial end face of the rotor, and the received carrier reflection signal is used as a radio frequency input signal of the carrier circuit mixer after passing through the carrier circuit radio frequency cable for receiving and the carrier circuit circulator; the reference signal is amplified by the signal power amplification module and then is used as a local oscillation input signal of the carrier wave circuit frequency mixer; the carrier way mixer outputs two paths of orthogonal demodulation signals, and the two paths of orthogonal demodulation signals are transmitted to a computer after being preprocessed by a signal conditioning and collecting module;
the reference signal generated by the microwave signal generation module is transmitted to the end face of the microwave reference sensor through the signal power amplification module, the reference circuit circulator and the reference circuit radio frequency cable in sequence to be reflected and returned, and the returned signal is transmitted to the reference circuit circulator through the reference circuit radio frequency cable for receiving and then is output and used as a local oscillation input signal of the first reference circuit frequency mixer; a carrier signal generated by the microwave signal generation module is amplified and then is used as a radio frequency input signal of the first reference path mixer; the first reference path mixer outputs two paths of orthogonal demodulation signals, and the two paths of orthogonal demodulation signals are transmitted to a computer after being preprocessed by a signal conditioning and collecting module;
a carrier signal generated by the microwave signal generation module passes through the signal power amplification module to be used as a radio frequency input signal of a second reference path mixer; amplifying the reference signal generated by the microwave signal generation module to be used as a local oscillator input signal of the second path of reference path frequency mixer; the second reference path mixer outputs one path of orthogonal demodulation signal, and the orthogonal demodulation signal is transmitted to the computer after being preprocessed by the signal conditioning acquisition module;
the computer processes the input signal to obtain the rotor and stator axial clearance;
the microwave signal generating module includes: the system comprises a clock reference, a controller, a carrier circuit phase-locked loop, a carrier circuit voltage-controlled oscillator, a carrier circuit loop filter, a reference circuit phase-locked loop, a reference circuit voltage-controlled oscillator and a reference circuit loop filter;
the signal power amplification module includes: a carrier wave path power amplifier, a first carrier wave path medium power amplifier, a second carrier wave path medium power amplifier, a first reference path medium power amplifier, a second reference path medium power amplifier and a reference path power amplifier;
the signal receiving and mixing module comprises: a reference path mixer, a reference path radio frequency low noise amplifier, a first low pass filter (17), a second low pass filter (18), a reference path mixer, a third low pass filter (20), a fourth low pass filter (21), a fifth low pass filter (22), a carrier path mixer and a carrier path radio frequency low noise amplifier;
the clock reference provides a stable frequency reference for the system;
the controller sets the carrier wave path phase-locked loop to work at carrier frequency omegarIn the mode; the carrier wave circuit phase-locked loop outputs a pulse current signal through an internal charge pump, and the pulse current signal is subjected to band-pass filtering through a carrier wave circuit loop filter, so that the carrier wave circuit voltage-controlled oscillator outputs carrier frequency omegarSimultaneously, the phase difference between a frequency multiplication signal of the clock reference and a carrier feedback signal of the carrier circuit voltage-controlled oscillator is monitored in real time through an internal phase discriminator, and the phase difference between the two signals is zero;
after the power of a carrier circuit power amplifier is amplified, a carrier signal output by the carrier circuit voltage-controlled oscillator enters a first port of the carrier circuit circulator and is output from a second port of the carrier circuit circulator; the second port of the carrier wave circulator is connected with a carrier wave radio frequency cable, the carrier wave radio frequency cable is connected with a microwave carrier sensor, the microwave carrier sensor transmits a carrier signal to the axial end face of the measured rotor, receives a carrier reflection signal of the axial end face of the rotor at the same time, and the carrier reflection signal is transmitted back to the second port of the carrier wave circulator through the carrier wave radio frequency cable and is output from the third port of the carrier wave circulator;
the controller sets the phase-locked loop of the reference path to work at the reference frequency omegasIn the mode; the reference circuit phase-locked loop outputs a pulse current signal through an internal charge pump, and after the pulse current signal is subjected to band-pass filtering through a reference circuit loop filter, the reference circuit voltage-controlled oscillator outputs a reference frequency omegasSimultaneously, the phase difference between a frequency multiplication signal of a clock reference and a reference feedback signal of a reference circuit voltage-controlled oscillator is monitored in real time through an internal phase discriminator, and the phase difference between the two signals is zero;
a reference signal output by the reference circuit voltage-controlled oscillator enters a first port of the reference circuit circulator after being amplified by the power of the reference circuit power amplifier and is output from a second port of the reference circuit circulator; a second port of the reference path circulator is connected with a reference path radio frequency cable, the reference path radio frequency cable is connected with a reference path microwave reference sensor, and reference signals transmitted by the reference path microwave reference sensor are totally reflected on the end face of the sensor, pass through the reference path radio frequency cable, are input back to the second port of the reference path circulator and are output from a third port of the reference path circulator;
the reference path microwave reference sensor structure includes: the microwave antenna, the metal hollow sleeve and the metal reference reflecting end surface are arranged on the base; the metal reference reflecting end face is used as the end face of the reference path microwave reference sensor, and all reference signals transmitted by the reference path microwave reference sensor are reflected back to the reference path radio frequency cable;
the gap value s between the microwave antenna and the metal reference reflecting end surface is millimeter-sized and is not zero;
the reference signal output by the third port of the reference path circulator is amplified by the reference path radio frequency low noise amplifier and then is used as the local oscillator of the reference path frequency mixerInput signal Y2(ii) a Meanwhile, a carrier signal output by the carrier circuit voltage-controlled oscillator is amplified by the medium gain of the medium power amplifier in the carrier circuit and then is used as a radio frequency input signal X of the reference circuit frequency mixer1(ii) a The reference path mixer outputs two paths of orthogonal demodulation signals which are respectively subjected to a first low-pass filter (17) and a second low-pass filter (18) to form ZI1And ZQ1The two paths of signals are pre-processed by a signal conditioning and collecting module and then transmitted to a computer;
the carrier signal output by the third port of the carrier circuit circulator is amplified by the carrier circuit radio frequency low noise amplifier and then is used as the radio frequency input signal Y of the carrier circuit mixer1(ii) a Meanwhile, a reference signal output by the reference circuit voltage-controlled oscillator is amplified by the medium gain of the medium power amplifier in the reference circuit and then is used as a local oscillator input signal X of the carrier circuit frequency mixer2(ii) a The carrier way mixer outputs two paths of orthogonal demodulation signals which are respectively processed by a fourth low-pass filter (21) and a fifth low-pass filter (22) to be ZI2And ZQ2The two paths of signals are also transmitted to the computer after being preprocessed by the signal conditioning and collecting module;
the carrier signal output by the carrier circuit voltage-controlled oscillator is amplified by the medium gain of the medium power amplifier in the carrier circuit and then is used as the radio frequency input signal Y of the reference circuit frequency mixer3(ii) a Meanwhile, a reference signal output by the voltage-controlled oscillator of the reference path is amplified by the medium gain of the medium power amplifier of the reference path and then is used as a local oscillator input signal X of the frequency mixer of the reference path3(ii) a The reference path mixer outputs a path of orthogonal demodulation signal which is Z after passing through a third low-pass filter (20)I3The signal is pre-processed by the signal conditioning and collecting module and then transmitted to the computer;
the signal conditioning and collecting module consists of a signal amplifying circuit, a signal filtering circuit and an analog-digital conversion circuit;
wherein, a microwave double-path reference structure and a carrier frequency omega of carrier path phase-locked loop work are adoptedrReference frequency omega for operating with reference path phase-locked loopsThe carrier wave path radio frequency cable and the reference path radio frequency cable need to be as close as possible, and the same length and type of radio frequency wire is used as the carrier wave path radio frequency cable and the reference path radio frequency cableThe cables are closely arranged side by side, so that the radio frequency signal phase delay amount drift values on the carrier wave path radio frequency cable and the reference path radio frequency cable caused by the length change of the radio frequency cable or the change of the environmental temperature in the working process of an aircraft engine are equal;
local oscillator input signal Y of input reference path frequency mixer2And a radio frequency input signal X1Represented by formula (1) and formula (2), respectively:
wherein A is1For the radio-frequency input signal X1Amplitude of (A)5For local oscillator input signal Y2Amplitude of the reflected portion of the end face of the medium microwave reference sensor, A6For local oscillator input signal Y2Amplitude, omega, of RF co-frequency crosstalk part caused by low isolation of RF chip or circulatorsAs reference frequency, ωrIs the carrier frequency and is,for the radio-frequency input signal X1The phase of (a) is determined,for local oscillator input signal Y2The end face reflection part of the medium microwave reference sensor delays the phase on the radio frequency cable of the reference path,for local oscillator input signal Y2The phase of the radio frequency co-frequency crosstalk part delayed on a transmission path due to low isolation of a radio frequency chip or a circulator;
two-path orthogonal demodulation signal division output by reference path mixerThe frequency omega is filtered by a first low-pass filter (17) and a second low-pass filter (18) respectivelyr+ωsAfter the frequency component of (2), the signal Z is obtainedI1And ZQ1Expressed by formulas (3) and (4), respectively:
wherein k' is a reference road amplitude imbalance factor,as a reference path phase imbalance factor, ωIF=ωs-ωrIs an intermediate frequency;
radio frequency input signal Y of input carrier circuit mixer1And local oscillator input signal X2Expressed by formula (5) and formula (6), respectively:
wherein A is2For local oscillator input signal X2Amplitude of (A)3For the radio-frequency input signal Y1Amplitude of the reflected signal portion of the intermediate carrier, A4For the radio-frequency input signal Y1Amplitude, omega, of RF co-frequency crosstalk part caused by low isolation of RF chip or circulatorsAs reference frequency, ωrIs the carrier frequency and is,for local oscillator input signal X2The phase of (a) is determined,for the radio-frequency input signal Y1The phase of the intermediate carrier reflected signal portion delayed on the carrier path radio frequency cable (29),for the radio-frequency input signal Y1Wherein the radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator delays the phase on the transmission path,for the radio-frequency input signal Y1The middle carrier reflected signal part is subjected to the phase to be detected generated by the change of the rotor stator axial gap;
two paths of orthogonal demodulation signals output by the carrier path mixer are respectively filtered by a fourth low-pass filter (21) and a fifth low-pass filter (22) to remove omega frequencyr+ωsAfter the frequency component of (2), the signal Z is obtainedI2And ZQ2And are represented by formula (7) and formula (8), respectively:
ZI2=SI_IF(t)+SI_le(t) (7)
ZQ2=SQ_IF(t)+SQ_le(t) (8)
is ZI2The radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator in the radio frequency co-frequency crosstalk part;
is ZQ2The radio frequency co-frequency crosstalk part caused by low isolation of the radio frequency chip or the circulator in the radio frequency co-frequency crosstalk part;
wherein k is the carrier path amplitude imbalance factor,is the carrier wave path phase unbalance factor;
further, a radio frequency input signal Y is input to a reference path mixer (19)3And local oscillator input signal X3Expressed by formula (9) and formula (10), respectively:
wherein A is7For local oscillator input signal X3The amplitude of (a) of (b) is,for local oscillator input signal X3Phase of (A)8For the radio-frequency input signal Y3The amplitude of (a) of (b) is,for the radio-frequency input signal Y3The phase of (d);
one path of demodulation signal output by the reference path mixer (19) is filtered by a third low-pass filter (20) to remove omegar+ωsAfter the frequency component of (2), the signal Z is obtainedI3Represented by formula (11):
in the computer, for the reference path, the Z from the transmissionI1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'I(d) Is a reaction of ZQ1And ZI3Performing mixing operation and low-pass filtering to obtain signal V'Q(d) (ii) a For carrier paths, Z from the transmissionI2And ZI3Performing mixing operation and low-pass filtering to obtain signal VI(d) Is a reaction of ZQ2And ZI3Performing mixing operation and low-pass filtering to obtain signal VQ(d);V'I(d)、V'Q(d)、VI(d) And VQ(d) Expressed by formulas (12), (13), (14) and (15), respectively:
in the formulas (12), (13)In (14) and (15), k'),Ale、A'leAre constant and do not vary with rotor-stator axial clearance, and AIFOnly the rotor and stator axial clearance is related, and the inverse proportion relation is formed by the second power of the rotor and stator axial clearance d; a'tip、The axial clearance of the rotor and the stator does not change along with the change of the axial clearance of the rotor and the stator, but drifts along with the change of the temperature of the working environment;
based on the microwave phase ranging principle:
wherein ω is1Is the spatial angular frequency of the transmitted microwave radio frequency signal;
from formulae (14), (15) and (16):
using the frequency spectrum of V (d) signal mainly at main frequency omega1Image frequency-omega1And the DC frequency, the amplitude values at the three frequencies are respectively A (omega) through space distance scanning, namely, rotor and stator axial gap sampling at equal intervals1)、A(-ω1) A (0); the amplitude-phase imbalance correction factor is expressed by equation (18), equation (19), equation (20), and equation (21):
the method adopts an improved co-channel interference signal suppression step based on spatial distance scanning, and a model for suppressing the co-channel interference signals of the carrier channel is shown as a formula (22):
therefore, the rotor-stator axial gap d after suppressing the carrier channel co-channel interference signal is expressed by equation (23):
wherein,the axial clearance of the rotor to be measured does not change, but drifts along with the temperature change of the working environment;
the determination method comprises the following steps: when the system is calibrated, the reference path radio frequency cable is not connected with the microwave reference sensor and is directly connected with the dummy load to realize the complete absorption of the reference signal, and the formula (3), the formula (4), the formula (12) and the formula (13) are respectively expressed as a formula (24) and a formula (25)) Formula (26) and formula (27):
obtained from formulae (24), (25):
Z'1(t) signal at main frequency ωIFImage frequency-omegaIFThe amplitudes at these two frequencies are A (ω)IF)、A(-ωIF) (ii) a The amplitude-phase imbalance correction factor is expressed by equations (29) and (30):
the model for suppressing the co-channel interference signal of the reference channel is shown as formula (31):
thus, the radio frequency input signal Y2Phase of medium microwave reference sensor end face reflection part delayed on reference path radio frequency cableRepresented by formula (32):
radio frequency signal phase delay amount on carrier wave path radio frequency cable caused by environment temperature change in working process of aircraft engineAnd the phase delay amount of the radio frequency signal on the reference path radio frequency cable (30)Equally, by equations (23) and (32), the real-time online high-precision measurement method of the rotor-stator axial gap d is represented by equation (33):
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Effective date of registration: 20240115 Address after: Office Building 451-04, Xuefu Industrial Zone Management Committee, Xiqing District, Tianjin, 300000 Patentee after: SMARTMENS (TIANJIN) TECHNOLOGY CO.,LTD. Address before: 300072 Tianjin City, Nankai District Wei Jin Road No. 92 Patentee before: Tianjin University |