CN112462358A - 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 PDF

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CN112462358A
CN112462358A CN202011071825.4A CN202011071825A CN112462358A CN 112462358 A CN112462358 A CN 112462358A CN 202011071825 A CN202011071825 A CN 202011071825A CN 112462358 A CN112462358 A CN 112462358A
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carrier
frequency
radio frequency
path
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CN112462358B (en
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段发阶
牛广越
傅骁
蒋佳佳
程仲海
刘志博
陈越
郑好
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Smartmens Tianjin Technology Co ltd
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Tianjin University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/06—Systems determining position data of a target
    • G01S13/08—Systems for measuring distance only
    • G01S13/32—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
    • G01S13/36—Systems for measuring distance only using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated with phase comparison between the received signal and the contemporaneously transmitted signal
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/023—Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B15/00—Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/021—Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/35—Details of non-pulse systems
    • G01S7/352—Receivers
    • G01S7/354—Extracting wanted echo-signals

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

Method and device for improving rotor and stator axial clearance measurement precision
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 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;
controller setting reference pathThe phase-locked loop operates at a 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:
Figure BDA0002715293270000041
Figure BDA0002715293270000042
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,
Figure BDA0002715293270000043
for the radio-frequency input signal X1The phase of (a) is determined,
Figure BDA0002715293270000044
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,
Figure BDA0002715293270000045
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:
Figure BDA0002715293270000046
Figure BDA0002715293270000047
wherein k' is a reference road amplitude imbalance factor,
Figure BDA0002715293270000048
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:
Figure BDA0002715293270000049
Figure BDA00027152932700000410
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,
Figure BDA00027152932700000411
for local oscillator input signal X2The phase of (a) is determined,
Figure BDA00027152932700000412
for the radio-frequency input signal Y1The phase of the intermediate carrier reflected signal portion delayed on the carrier path radio frequency cable 29,
Figure BDA00027152932700000413
for the radio-frequency input signal Y1Due to radio frequency coreThe radio frequency co-frequency crosstalk part caused by low isolation of the sheet or the circulator delays the phase on the transmission path,
Figure BDA00027152932700000414
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)
wherein the content of the first and second substances,
Figure BDA0002715293270000051
is ZI2The carrier reflection signal portion of (1);
Figure BDA0002715293270000052
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;
Figure BDA0002715293270000053
is ZQ2The carrier reflection signal portion of (1);
Figure BDA0002715293270000054
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,
Figure BDA0002715293270000055
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:
Figure BDA0002715293270000056
Figure BDA0002715293270000057
wherein A is7For local oscillator input signal X3The amplitude of (a) of (b) is,
Figure BDA0002715293270000058
for local oscillator input signal X3Phase of (A)8For the radio-frequency input signal Y3The amplitude of (a) of (b) is,
Figure BDA0002715293270000059
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):
Figure BDA00027152932700000510
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 passFiltering 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:
Figure BDA00027152932700000511
Figure BDA00027152932700000512
Figure BDA00027152932700000513
Figure BDA00027152932700000514
wherein the content of the first and second substances,
Figure BDA0002715293270000061
Figure BDA0002715293270000062
in formulae (12), (13), (14) and (15), k'; and,
Figure BDA0002715293270000063
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、
Figure BDA0002715293270000064
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:
Figure BDA0002715293270000065
wherein ω is1Is the spatial angular frequency of the transmitted microwave radio frequency signal;
from formulae (14), (15) and (16):
Figure BDA0002715293270000066
wherein the content of the first and second substances,
Figure BDA0002715293270000067
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):
Figure BDA0002715293270000068
Figure BDA0002715293270000069
Figure BDA00027152932700000610
Figure BDA00027152932700000611
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):
Figure BDA00027152932700000612
therefore, the rotor-stator axial gap d after suppressing the carrier channel co-channel interference signal is expressed by equation (23):
Figure BDA00027152932700000613
wherein the content of the first and second substances,
Figure BDA0002715293270000071
the axial clearance of the rotor to be measured does not change, but drifts along with the temperature change of the working environment;
Figure BDA0002715293270000072
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, but is directly connected with the dummy load, so that the complete absorption of the reference signal is realized, and the formula (3), the formula (4), the formula (12) and the formula (13) are respectively expressed as a formula (24), a formula (25), a formula (26) and a formula (27):
Figure BDA0002715293270000073
Figure BDA0002715293270000074
Figure BDA0002715293270000075
Figure BDA0002715293270000076
the following equations 24 and 25 can be obtained:
Figure BDA0002715293270000077
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):
Figure BDA0002715293270000078
Figure BDA0002715293270000079
the model for suppressing the co-channel interference signal of the reference channel is shown as formula (31):
Figure BDA00027152932700000710
thus, the radio frequency input signal Y2Phase of medium microwave reference sensor end face reflection part delayed on reference path radio frequency cable
Figure BDA00027152932700000711
Represented by formula (32):
Figure BDA00027152932700000712
radio frequency signal phase delay amount on carrier wave path radio frequency cable caused by environment temperature change in working process of aircraft engine
Figure BDA00027152932700000713
And the phase delay of the RF signal on the RF cable 30 of the reference path
Figure BDA00027152932700000714
Equal, real-time on-line high-precision measurement method for rotor and stator axial clearance d by formula (23) and formula (32)Represented by formula (33):
Figure BDA00027152932700000715
wherein c, f,
Figure BDA00027152932700000716
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 signal
Figure BDA0002715293270000081
The 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 inhibited
Figure BDA0002715293270000082
The 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 output from the third port of the reference loop circulator 28 is amplified by the reference loop rf low noise amplifier 16 and then used as the local oscillator input signal Y of the reference loop mixer 152(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 channels of informationThe 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 operatessThe carrier way radio frequency cable 29 and the reference way radio frequency cable 30 are close to each other as much as possible, and radio frequency cables with the same length and the same type are used and are arranged side by side in a close mounting manner, so that radio frequency signal phase delay amount drifting 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 accuracy 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:
Figure BDA0002715293270000101
Figure BDA0002715293270000111
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,
Figure BDA0002715293270000112
for the radio-frequency input signal X1The phase of (a) is determined,
Figure BDA0002715293270000113
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,
Figure BDA0002715293270000114
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:
Figure BDA0002715293270000115
Figure BDA0002715293270000116
wherein k' is a reference road amplitude imbalance factor,
Figure BDA0002715293270000117
phase of reference pathImbalance 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:
Figure BDA0002715293270000118
Figure BDA0002715293270000119
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,
Figure BDA00027152932700001110
for local oscillator input signal X2The phase of (a) is determined,
Figure BDA00027152932700001111
for the radio-frequency input signal Y1The phase of the intermediate carrier reflected signal portion delayed on the carrier path radio frequency cable 29,
Figure BDA00027152932700001112
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,
Figure BDA00027152932700001113
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 positive lines output by the carrier mixer 23The AC demodulation signal is filtered by a low pass filter 21 and a 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)
wherein the content of the first and second substances,
Figure BDA00027152932700001114
is ZI2The carrier reflection signal portion of (1);
Figure BDA0002715293270000121
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;
Figure BDA0002715293270000122
is ZQ2The carrier reflection signal portion of (1);
Figure BDA0002715293270000123
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,
Figure BDA0002715293270000124
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:
Figure BDA0002715293270000125
Figure BDA0002715293270000126
wherein A is7For local oscillator input signal X3The amplitude of (a) of (b) is,
Figure BDA0002715293270000127
for local oscillator input signal X3Phase of (A)8For the radio-frequency input signal Y3The amplitude of (a) of (b) is,
Figure BDA0002715293270000128
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:
Figure BDA0002715293270000129
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:
Figure BDA00027152932700001210
Figure BDA00027152932700001211
Figure BDA00027152932700001212
Figure BDA00027152932700001213
wherein the content of the first and second substances,
Figure BDA00027152932700001214
Figure BDA00027152932700001215
in formulae 12, 13, 14 and 15, k'),
Figure BDA0002715293270000131
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、
Figure BDA0002715293270000132
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
Figure BDA0002715293270000133
Wherein ω is1Is the spatial angular frequency of the transmitted microwave radio frequency signal;
the following equations 14, 15 and 16 can be obtained:
Figure BDA0002715293270000134
wherein the content of the first and second substances,
Figure BDA0002715293270000135
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:
Figure BDA0002715293270000136
Figure BDA0002715293270000137
Figure BDA0002715293270000138
Figure BDA0002715293270000139
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:
Figure BDA00027152932700001310
therefore, the rotor-stator axial gap d after suppressing the co-channel interference signal on the carrier path can be represented by equation 23:
Figure BDA00027152932700001311
wherein the content of the first and second substances,
Figure BDA00027152932700001312
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,
Figure BDA0002715293270000141
the determination method comprises the following steps: when the system is calibrated, the reference path rf cable 30 is not connected to the microwave reference sensor 32, but directly connected to the dummy load, so as to achieve complete absorption of the reference signal, where equations 3, 4, 12, and 13 can be expressed as equations 24, 25, 26, and 27, respectively:
Figure BDA0002715293270000142
Figure BDA0002715293270000143
Figure BDA0002715293270000144
Figure BDA0002715293270000145
the following equations 24 and 25 can be obtained:
Figure BDA0002715293270000146
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:
Figure BDA0002715293270000147
Figure BDA0002715293270000148
the model for suppressing the co-channel interference signal of the reference channel is shown as formula 31:
Figure BDA0002715293270000149
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 30
Figure BDA00027152932700001410
Can be represented by equation 32:
Figure BDA00027152932700001411
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 engine
Figure BDA00027152932700001412
And the phase delay of the RF signal on the RF cable 30 of the reference path
Figure BDA00027152932700001413
Equality, from equation 23 and equation 32, real time of rotor-stator axial clearance dThe on-line high-precision measurement method can be represented by equation 33:
Figure BDA00027152932700001414
wherein c, f,
Figure BDA00027152932700001415
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 suppressed
Figure BDA0002715293270000151
The 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 inhibited
Figure BDA0002715293270000152
The 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 29
Figure BDA0002715293270000153
And the phase delay of the RF signal on the RF cable 30 of the reference path
Figure BDA0002715293270000154
Under 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 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 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 lowAfter passing through the filter 20, is ZI3The 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 obtain 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 suppressed
Figure BDA0002715293270000171
The 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 inhibited
Figure BDA0002715293270000172
The 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 29
Figure BDA0002715293270000173
And the phase delay of the RF signal on the RF cable 30 of the reference path
Figure BDA0002715293270000174
The 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 (3)

1. The utility model provides an improve device of rotor stator axial clearance measurement accuracy, characterized by includes: the system comprises 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 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.
2. The apparatus for improving the accuracy of rotor-stator axial gap measurement according to claim 1, wherein the microwave signal generating module comprises: 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 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; 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 respectively pass through a fourth low-pass filter (21) and a fifth low-pass filter (22)After is 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.
3. A method for improving the measurement accuracy of rotor-stator axial clearance, which is characterized by being realized by the device for improving the measurement accuracy of rotor-stator axial clearance in claim 2, wherein a microwave two-way reference structure is adopted, and the carrier frequency ω of carrier-wave phase-locked loop operation is 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:
Figure FDA0002715293260000031
Figure FDA0002715293260000032
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,
Figure FDA0002715293260000033
for the radio-frequency input signal X1The phase of (a) is determined,
Figure FDA0002715293260000034
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,
Figure FDA0002715293260000035
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:
Figure FDA0002715293260000036
Figure FDA0002715293260000037
wherein k' is a reference road amplitude imbalance factor,
Figure FDA0002715293260000038
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:
Figure FDA0002715293260000039
Figure FDA00027152932600000310
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,
Figure FDA00027152932600000311
for local oscillator input signal X2The phase of (a) is determined,
Figure FDA00027152932600000312
for the radio-frequency input signal Y1The phase of the intermediate carrier reflected signal portion delayed on the carrier path radio frequency cable 29,
Figure FDA00027152932600000313
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,
Figure FDA00027152932600000314
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)
wherein the content of the first and second substances,
Figure FDA0002715293260000041
is ZI2The carrier reflection signal portion of (1);
Figure FDA0002715293260000042
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;
Figure FDA0002715293260000043
is ZQ2The carrier reflection signal portion of (1);
Figure FDA0002715293260000044
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,
Figure FDA0002715293260000045
is the carrier wave path phase unbalance factor;
further, the RF input is input to a reference mixer 19Signal Y3And local oscillator input signal X3Can be represented by formula (9) and formula 10, respectively:
Figure FDA0002715293260000046
Figure FDA0002715293260000047
wherein A is7For local oscillator input signal X3The amplitude of (a) of (b) is,
Figure FDA0002715293260000048
for local oscillator input signal X3Phase of (A)8For the radio-frequency input signal Y3The amplitude of (a) of (b) is,
Figure FDA0002715293260000049
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):
Figure FDA00027152932600000410
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:
Figure FDA0002715293260000051
Figure FDA0002715293260000052
Figure FDA0002715293260000053
Figure FDA0002715293260000054
wherein the content of the first and second substances,
Figure FDA0002715293260000055
Figure FDA0002715293260000056
in formulae (12), (13), (14) and (15), k'; and,
Figure FDA0002715293260000057
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、
Figure FDA0002715293260000058
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:
Figure FDA0002715293260000059
wherein ω is1Is the spatial angular frequency of the transmitted microwave radio frequency signal;
from formulae (14), (15) and (16):
Figure FDA00027152932600000510
wherein the content of the first and second substances,
Figure FDA00027152932600000511
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):
Figure FDA00027152932600000512
Figure FDA00027152932600000513
Figure FDA00027152932600000514
Figure FDA00027152932600000515
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):
Figure FDA0002715293260000061
therefore, the rotor-stator axial gap d after suppressing the carrier channel co-channel interference signal is expressed by equation (23):
Figure FDA0002715293260000062
wherein the content of the first and second substances,
Figure FDA00027152932600000615
the axial clearance of the rotor to be measured does not change, but drifts along with the temperature change of the working environment;
Figure FDA00027152932600000616
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, but is directly connected with the dummy load, so that the complete absorption of the reference signal is realized, and the formula (3), the formula (4), the formula (12) and the formula (13) are respectively expressed as a formula (24), a formula (25), a formula (26) and a formula (27):
Figure FDA0002715293260000063
Figure FDA0002715293260000064
Figure FDA0002715293260000065
Figure FDA0002715293260000066
the following equations 24 and 25 can be obtained:
Figure FDA0002715293260000067
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):
Figure FDA0002715293260000068
Figure FDA0002715293260000069
the model for suppressing the co-channel interference signal of the reference channel is shown as formula (31):
Figure FDA00027152932600000610
thus, the radio frequency input signal Y2Phase of medium microwave reference sensor end face reflection part delayed on reference path radio frequency cable
Figure FDA00027152932600000611
Represented by formula (32):
Figure FDA00027152932600000612
radio frequency signal phase delay amount on carrier wave path radio frequency cable caused by environment temperature change in working process of aircraft engine
Figure FDA00027152932600000613
And the phase delay of the RF signal on the RF cable 30 of the reference path
Figure FDA00027152932600000614
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):
Figure FDA0002715293260000071
wherein c, f,
Figure FDA0002715293260000072
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.
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