CN211060879U - Rotating blade tip clearance measurement system based on RMS - Google Patents
Rotating blade tip clearance measurement system based on RMS Download PDFInfo
- Publication number
- CN211060879U CN211060879U CN201921277682.5U CN201921277682U CN211060879U CN 211060879 U CN211060879 U CN 211060879U CN 201921277682 U CN201921277682 U CN 201921277682U CN 211060879 U CN211060879 U CN 211060879U
- Authority
- CN
- China
- Prior art keywords
- sensor
- simulation
- module
- rotor
- rms
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn - After Issue
Links
- 238000005259 measurement Methods 0.000 title claims abstract description 23
- 238000004088 simulation Methods 0.000 claims abstract description 39
- 238000006243 chemical reaction Methods 0.000 claims abstract description 22
- 238000006073 displacement reaction Methods 0.000 claims abstract description 18
- 238000007781 pre-processing Methods 0.000 claims abstract description 17
- 238000012360 testing method Methods 0.000 claims abstract description 12
- 230000008054 signal transmission Effects 0.000 claims abstract description 8
- 239000000523 sample Substances 0.000 description 12
- 238000013461 design Methods 0.000 description 7
- 238000012545 processing Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 238000005070 sampling Methods 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 3
- 238000011088 calibration curve Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 238000000691 measurement method Methods 0.000 description 2
- 230000000737 periodic effect Effects 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000002307 isotope ratio mass spectrometry Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
Images
Landscapes
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
The utility model discloses a rotating blade apex clearance measurement system based on RMS, including sensor and rotor and rotating blade that are located the engine machine casket, still include dynamic calibration test bench and signal preprocessing module, RMS conversion module, signal acquisition module and the host computer that links to each other in proper order; the sensor is connected with the signal preprocessing module through a signal transmission cable; the dynamic calibration test bed comprises a driving motor, a simulation rotor, a simulation blade, a supporting platform, a sensor bracket and a high-precision displacement platform; the simulation rotor and the high-precision displacement platform are both arranged on the upper surface of the supporting platform; a sensor bracket is arranged on the high-precision displacement platform, the simulation rotor is driven by a driving motor, clamping grooves for clamping the simulation blades are arranged on the circumference of the simulation rotor at equal intervals, and the simulation blades are additionally arranged on the clamping grooves; when the calibration is carried out in advance, the sensor is fixed on the sensor bracket; during actual measurement, the sensor is fixed on the engine casing.
Description
Technical Field
The utility model belongs to apex clearance measurement field especially utilizes sensor signal processing field, specifically is a rotating vane apex clearance measurement system based on RMS.
Background
The blade tip clearance refers to the radial distance between the top end (blade tip) of a rotor blade in the aircraft engine and the inner wall of a casing. The blade tip clearance of the rotor blade of the aircraft engine is an important parameter for performance analysis and evaluation, and has important influence on the working efficiency, safety, reliability and the like of the engine.
The principle of the capacitance type blade tip clearance measurement system is based on the capacitance of a sensor probe and the top end of a blade, and the relation between the capacitance and the clearance is established. The measuring probe is fixed in a casing at the top end of the blade and forms one pole of the capacitor, and the blade tip of the engine rotor sweeps across the front of the probe during operation so as to form the other pole of the capacitor. The measured capacitance is a function of the electrode geometry, the distance between the electrodes and the inter-electrode medium. In general, the working medium of the engine is not changed, and for the blade with the unchanged geometric shape of the blade tip, the area of the blade tip opposite to the probe is a fixed value, so that the relation between the capacitance and the distance is established only by calibration, and the distance between the blade tip and the probe, namely the blade tip gap can be directly measured through the capacitance.
The typical military engine has a blade thickness of 1-2 mm, a rotation speed of a blade rotor of about 0-20000 r/min, and the number of blades is usually 8-100. Assuming that the rotation speed is 18000r/min and the number of blades is 60, signals of tens of thousands of blades are acquired and processed every second, and the dynamic response time of the sensor is only about 5us, which requires the sampling frequency of data to be at least 5 MHz. At such a high sampling frequency, the blade information is usually collected by using multiple sensors and multiple channels to measure and collect the blade information at the same time, which results in a larger data volume. The requirement for subsequent data acquisition and processing is high. Meanwhile, in order to realize online analysis of the blade tip clearance data and guarantee real-time display of waveforms, a large number of complex blade tip clearance acquisition signals need to be uploaded in real time, the requirement on the real-time performance of upper computer software is high, and the hardware cost and the burden are increased.
SUMMERY OF THE UTILITY MODEL
The utility model discloses an overcome among the prior art data acquisition circuit design requirement sampling frequency height, data transmission volume big, thereby lead to follow-up system real-time nature to require higher and design more complicated scheduling problem, provide a rotating vane apex clearance measurement system based on RMS to design rotating vane developments and mark the test bench, confirm the corresponding relation between apex clearance signal's RMS value and apex clearance value and mark the relational expression. And according to the obtained calibration relation between the blade tip clearance signal RMS value and the blade tip clearance value, building a rotating blade tip clearance measuring system based on the RMS, and realizing the real-time measurement of the blade tip clearance of the engine blade. The difficulty of subsequent signal acquisition and processing can be reduced; converting the high-frequency tip clearance signal into a direct current level for output; the efficiency of the measuring system is improved.
The utility model aims at realizing through the following technical scheme:
a rotating blade tip clearance measuring system based on RMS comprises a sensor, a rotor and a rotating blade, a dynamic calibration test bed, a signal preprocessing module, an RMS conversion module, a signal acquisition module and an upper computer, wherein the rotor and the rotating blade are positioned in an engine casing; the sensor is connected with the signal preprocessing module through a signal transmission cable; the dynamic calibration test bed comprises a driving motor, a simulation rotor, a simulation blade, a supporting platform, a sensor bracket and a high-precision displacement platform; the simulation rotor and the high-precision displacement platform are both arranged on the upper surface of the supporting platform; the high-precision displacement platform is provided with a sensor support, a sensor can be fixed on the sensor support, and the sensor support and the sensor are driven to be close to or far away from the simulation rotor through the movement of the high-precision displacement platform; the simulation rotor is driven by a driving motor, and the driving motor is connected with the simulation rotor through a coupler; clamping grooves for clamping the simulation blades are formed in the circumference of the simulation rotor at equal intervals, and the simulation blades are additionally arranged on the clamping grooves; when in pre-calibration, a sensor is fixed on a sensor bracket of a dynamic calibration test bed to form a dynamic calibration system; during actual measurement, the sensor is fixed on the engine casing.
Furthermore, the RMS conversion module comprises a full-wave rectification module, a square/divider functional module, a low-pass filter module, a mirror current source module and a buffer amplifier module which are connected in sequence; the mirror current source module is connected with the square/divider functional module.
Compared with the prior art, the utility model discloses a beneficial effect that technical scheme brought is:
1. the utility model discloses to engine rotating vane apex clearance signal data volume big and complicated, problem such as signal frequency height utilizes apex clearance signal RMS value to characterize apex clearance value, converts high frequency signal into direct current output, solves the complicated problem of follow-up signal processing.
2. The utility model discloses a dynamic calibration is in order to obtain apex clearance value d and apex clearance signal RMS value's demarcation relational expression, effectively improves rotating vane apex clearance measurement system's based on RMS accuracy.
3. Based on the utility model discloses a rotating vane apex clearance measurement system can realize effectively guaranteeing the safety of engine operation in-process to the real-time high accuracy measurement in high-speed rotating vane apex clearance in the engine.
Drawings
Fig. 1 shows the characteristics and form of the blade tip clearance signal according to the present invention.
Fig. 2 is the front view structure diagram of the middle dynamic calibration system of the present invention.
Fig. 3 is a schematic view of the top view structure of the dynamic calibration system of the present invention.
Fig. 4 is the utility model discloses well calibration curve sketch map and calibration relational expression.
Fig. 5 is a schematic structural diagram of the middle measuring system of the present invention.
Fig. 6 is a schematic diagram of the structure of the RMS conversion module according to the present invention.
Reference numerals: 1-rotor and rotating blade, 2-engine casing, 3-sensor, 4-signal transmission cable, 5-signal preprocessing module, 6-RMS conversion module, 7-signal acquisition module, 8-upper computer, 9-driving motor, 10-analog rotor, 11-analog blade, 12-supporting platform, 13-sensor bracket, 14-high precision displacement platform, 15-full wave rectification module, 16-square/divider function module, 17-low pass filter module, 18-mirror current source module, 19-buffer amplifier module
Detailed Description
The utility model discloses a concrete embodiment is, provides a rotating vane apex clearance measurement system based on RMS, adopts the RMS value of apex clearance signal to characterize apex clearance value to design an RMS conversion circuit, in order to realize the RMS value conversion to the signal, and propose a blade dynamic calibration method to this signal processing scheme.
The utility model designs a rotating blade apex clearance measurement system based on RMS, including rotor and rotating blade 1, engine machine casket 2, sensor 3, signal transmission cable 4, signal preprocessing module 5, RMS conversion module 6, signal acquisition module 7 and host computer 8; wherein the RMS conversion module 6 comprises a full wave rectification module 15, a squaring/divider function module 16, a low pass filter module 17, a mirror current source module 18 and a buffer amplifier module 19; the dynamic calibration test bed comprises a driving motor 9, a simulation rotor 10, a simulation blade 11, a supporting platform 12, a sensor support 13 and a high-precision displacement platform 14.
In the dynamic calibration system, a sensor 3 is fixed on a sensor support 13 of a dynamic calibration test bed, a simulation rotor 10 and a high-precision displacement platform 14 are arranged on the upper surface of a supporting platform 12, the sensor support 13 is arranged on the high-precision displacement platform 14, a driving motor 9 is connected with the simulation rotor 10 through a coupler, clamping grooves for clamping the simulation blades are arranged on the circumference of the simulation rotor 10 at equal intervals, the simulation blades 11 are additionally arranged on the clamping grooves, the sensor 3 is connected with a signal preprocessing module 5 through a signal transmission cable 4, the signal preprocessing module 5 is connected with an RMS conversion module 6 through a circuit connecting wire, the RMS conversion module 6 is connected with a signal acquisition module 7 through a connecting wire, and the signal acquisition module 7 is connected with an upper computer 8 through a connecting wire.
In an actual measurement system, a sensor 3 is installed on an engine casing 2, the end face of a probe of the sensor 3 is over against the axes of a rotor and a rotating blade 1, the sensor 3 is connected with a signal preprocessing module 5 through a signal transmission cable 4, the signal preprocessing module 5 is connected with an RMS (root mean square) conversion module 6 through a circuit connecting line, the RMS conversion module 6 is connected with a signal acquisition module 7 through a connecting line, and the signal acquisition module 7 is connected with an upper computer 8 through a connecting line.
Referring to fig. 6, in the RMS conversion module 6, a full-wave rectification module 15, a squaring/dividing function module 16, a low-pass filter module 17, a mirror current source module 18, and a buffer amplifier module 19 are connected in sequence by circuit connection lines; the mirror current source module 18 is wired to the squaring/divider function module 19.
For overcoming among the current apex clearance measurement technique data acquisition circuit design requirement sampling frequency height, data transmission volume big, thereby lead to follow-up system real-time nature requirement higher and design more complicated scheduling problem, the utility model provides a rotating vane apex clearance measurement method based on RMS specifically as follows:
in the process of measuring the blade tip clearance, a sensor 3 arranged on an engine casing 2 senses the distance d from the probe end face of the sensor to the blade tip of the rotating blade 1 and converts the distance d into a weak electric signal, a signal preprocessing module 5 preprocesses the collected weak electric signal to output a blade tip clearance signal, other factors are considered to be fixed or influence factors are small, and the blade tip clearance signal is regarded as a single-value function related to the distance d and expressed as a single-value function related to the distance d
U＝f1(d)
When the rotor and the rotating blade 1 move to the position opposite to the sensor 3, the distance d between the rotor and the rotating blade is the minimum, namely the blade tip clearance value d0The voltage value of the tip clearance signal being at a maximum, i.e. corresponding to the amplitude A of the tip clearance signal, e.g.As shown in fig. 1, the tip clearance value can be calculated from the amplitude of the signal:
d0＝f2(A)
RMS (root Mean Square), called root Mean Square, has an amplitude A for a signal with a fixed periodxThe ratio to its RMS value is a fixed value, called the crest factor, denoted CF, and the relationship between them is
AxIs the amplitude of the periodic signal, xRMSIs the RMS value of the periodic signal.
The tip clearance signal may also be considered as a spike having a fixed period, the period being the time interval from the arrival of the previous blade at the sensor probe location to the departure of the next blade from the sensor probe location. Therefore, the RMS value of the tip clearance signal is proportional to the amplitude A according to the relationship, so that the RMS value of the tip clearance signal and the tip clearance value d can be established0The corresponding relationship between:
d0＝f3(URMS)
URMSthe RMS value of the tip clearance signal.
That is, the RMS value of the sensor output signal can be used to characterize the tip clearance value d0Using the RMS value and d value of the tip clearance signal0The calibration relation is used for calculating to obtain the tip clearance value of the rotating blade, so that the real-time high-precision measurement of the tip clearance of the high-speed rotating blade in the engine is realized, and the specific implementation steps are as follows:
(1) using a dynamic calibration test bed to build a dynamic calibration system to complete early-stage dynamic calibration
①, the sensor 3 is fixed on a sensor support of a dynamic calibration test bed, the sensor 3 is ensured to be over against the axle center of a simulation rotor, the end face of a sensor probe is parallel to the blade tip of the simulation blade, a high-precision displacement platform 14 is arranged on the upper surface of a supporting platform 12, a sensor support 13 is arranged on the high-precision displacement platform 14, a driving motor 9 is connected with the simulation rotor 10 through a coupler, the simulation blade 11 is additionally arranged on a clamping groove on the circumference of the simulation rotor 10 according to the real situation, the sensor 3 is connected with a signal preprocessing module 5 through a signal transmission cable 4, the signal preprocessing module 5 is connected with an RMS conversion module 6 through a circuit connecting wire, the RMS conversion module 6 is connected with a signal acquisition module 7 through a connecting wire, the signal acquisition module 7 is connected with an upper computer 8 through a connecting wire, and the construction of a blade tip gap dynamic calibration system;
② starting the driving motor 9 to drive the simulation rotor 10 and the simulation blade 11 to rotate and stabilize at a certain rotation speed, operating the dynamic calibration system for the blade tip clearance, and monitoring and recording the RMS value of the blade tip clearance signal obtained by the RMS conversion module in real time by using the upper computer 8;
③ moving the high-precision displacement platform 14 to drive the sensor bracket 13 to move back and forth, changing the tip clearance value, repeating the operations ② to obtain tip clearance signal RMS values under different tip clearance values;
④, making a dynamic calibration curve chart by the upper computer 8, determining the corresponding relation between the RMS value of the tip clearance signal and the tip clearance value, and further deducing a calibration relation d of the RMS value of the tip clearance signal and the tip clearance value0＝f3(URMS) As shown in fig. 4, it can be seen that the correlation coefficient of the equation reaches above 0.9, which indicates that the calibration curve truly reflects the corresponding relationship between the tip clearance value and the tip clearance signal RMS value, and effectively improves the accuracy of the rotating blade tip clearance measurement system based on RMS.
(2) Build blade tip clearance measurement system
As shown in fig. 5, the sensor 3 is mounted on the engine case 2, the probe end surface of the sensor 3 faces the axis of the rotor and the rotating blade 1, the sensor 3 is connected with the signal preprocessing module 5 through the signal transmission cable 4, the signal preprocessing module 5 is connected with the RMS conversion module 6 through a circuit connecting wire, the RMS conversion module 6 is connected with the signal acquisition module 7 through a connecting wire, and the signal acquisition module 7 is connected with the upper computer 8 through a connecting wire.
(3) Performing real-time measurement of rotating blade tip clearance
Starting the engine, the rotor drives the blade 1 to rotate and sweep a probe of the sensor 3, the blade tip clearance signal output by the signal preprocessing module 5 obtains an RMS value of the blade tip clearance signal through an RMS conversion module 6, the value is collected by a signal collecting module 7 as a result and uploaded to an upper computer 8 for calculation, and the value is substituted into the previously obtained calibration relation d0＝f3(URMS) And calculating to obtain a blade tip clearance value, and finishing the real-time measurement of the blade tip clearance of the rotating blade of the engine.
Further, the specific process of RMS value conversion in step (3) is as follows:
① the tip clearance signal is firstly input to the full-wave rectification module for processing 15, the input voltage signal is converted into a current signal for output, and the voltage input to the full-wave rectification module is set as VINThe current output by the full-wave rectification module 15 is converted into IIN；
② Current IINIs input to a squaring/divider functional block 16 in which the square of the input current, i.e. I, is first obtained by a squaring operationIN 2Then dividing the result by the final result I fed back by the mirror current source module 18OUTObtaining:
output ItThe averaging is achieved by the low pass filter module 17, resulting in the final output:
the transformed output signal has the following relationship:
the output result is the RMS value of the input signal:
IOUT＝IRMS；
③ will be filtered by low pass filteringThe final result output by the wave filter module 17 is input into the mirror current source module 18, and the mirror current source module 18 provides two paths of signal output; one of the outputs is used as feedback current to participate in the operation of the square/divider functional module, and the output signal of the mirror current source is equal to the input of the mirror current source module 18, i.e. IOUT(ii) a The other output of the mirror current source module 18 is also IOUTInput to the buffer amplifier module 19 to provide a low impedance voltage output, corresponding to the initial reverse operation of the full-wave rectifier module 15, passing the input current through the unity gain resistor R inside the buffer amplifier module 19LIs converted into an output voltage VRMS；
VOUT＝RL×IOUT＝VRMS
And finally obtaining the RMS value of the blade tip gap signal through the process.
The present invention is not limited to the above-described embodiments. The above description of the embodiments is intended to describe and illustrate the technical solutions of the present invention, and the above embodiments are merely illustrative and not restrictive. Without departing from the spirit of the invention and the scope of the appended claims, the person skilled in the art can make many changes in form and detail within the teaching of the invention.
Claims (2)
1. A rotating blade tip clearance measuring system based on RMS comprises a sensor, a rotor and a rotating blade, wherein the rotor and the rotating blade are positioned in an engine casing; the sensor is connected with the signal preprocessing module through a signal transmission cable; the dynamic calibration test bed comprises a driving motor, a simulation rotor, a simulation blade, a supporting platform, a sensor bracket and a high-precision displacement platform; the simulation rotor and the high-precision displacement platform are both arranged on the upper surface of the supporting platform; the high-precision displacement platform is provided with a sensor support, a sensor can be fixed on the sensor support, and the sensor support and the sensor are driven to be close to or far away from the simulation rotor through the movement of the high-precision displacement platform; the simulation rotor is driven by a driving motor, and the driving motor is connected with the simulation rotor through a coupler; clamping grooves for clamping the simulation blades are formed in the circumference of the simulation rotor at equal intervals, and the simulation blades are additionally arranged on the clamping grooves; when in pre-calibration, a sensor is fixed on a sensor bracket of a dynamic calibration test bed to form a dynamic calibration system; during actual measurement, the sensor is fixed on the engine casing.
2. An RMS-based rotating blade tip clearance measurement system as claimed in claim 1, wherein said RMS conversion module includes a full wave rectifier module, a squarer/divider function module, a low pass filter module, a mirror current source module and a buffer amplifier module connected in series; the mirror current source module is connected with the square/divider functional module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921277682.5U CN211060879U (en) | 2019-08-08 | 2019-08-08 | Rotating blade tip clearance measurement system based on RMS |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921277682.5U CN211060879U (en) | 2019-08-08 | 2019-08-08 | Rotating blade tip clearance measurement system based on RMS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN211060879U true CN211060879U (en) | 2020-07-21 |
Family
ID=71586584
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921277682.5U Withdrawn - After Issue CN211060879U (en) | 2019-08-08 | 2019-08-08 | Rotating blade tip clearance measurement system based on RMS |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN211060879U (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110455243A (en) * | 2019-08-08 | 2019-11-15 | 天津大学 | A kind of rotating vane tip clearance measuring system and method based on RMS |
| CN113671518A (en) * | 2021-08-27 | 2021-11-19 | 沈阳透平机械股份有限公司 | Wind tunnel compressor moving blade clearance measuring method |
| CN115306495A (en) * | 2022-08-26 | 2022-11-08 | 天津大学 | System and method for measuring blade top circle profile of rotating machinery rotor blade disc in real time |
| CN115324662A (en) * | 2022-05-30 | 2022-11-11 | 天津大学 | Fault diagnosis method based on blade tip clearance signal rotor dynamic characteristic analysis |
-
2019
- 2019-08-08 CN CN201921277682.5U patent/CN211060879U/en not_active Withdrawn - After Issue
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110455243A (en) * | 2019-08-08 | 2019-11-15 | 天津大学 | A kind of rotating vane tip clearance measuring system and method based on RMS |
| CN110455243B (en) * | 2019-08-08 | 2024-04-19 | 天津大学 | RMS-based rotary blade tip clearance measurement system and method |
| CN113671518A (en) * | 2021-08-27 | 2021-11-19 | 沈阳透平机械股份有限公司 | Wind tunnel compressor moving blade clearance measuring method |
| CN115324662A (en) * | 2022-05-30 | 2022-11-11 | 天津大学 | Fault diagnosis method based on blade tip clearance signal rotor dynamic characteristic analysis |
| CN115306495A (en) * | 2022-08-26 | 2022-11-08 | 天津大学 | System and method for measuring blade top circle profile of rotating machinery rotor blade disc in real time |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN211060879U (en) | Rotating blade tip clearance measurement system based on RMS | |
| CN110455243B (en) | RMS-based rotary blade tip clearance measurement system and method | |
| CN1129782C (en) | Method and device for automatic detection and control of wind tunnel speed | |
| CN110108794A (en) | A kind of adjustable contact force type supersonic guide-wave damage detection system | |
| CN106324538B (en) | A kind of shelf depreciation automated calibration system | |
| CN1696686A (en) | System for testing quality of cast in place concrete pile | |
| CN106767499A (en) | A kind of preform flexibility measuring method | |
| CN105758602A (en) | Truss girder bridge section buffeting force synchronous measurement method | |
| CN101718582A (en) | Tone testing method of wind power generator set | |
| CN103245291A (en) | Assembly accuracy detecting method for blade parts | |
| CN210666065U (en) | Calibration device of seismic intensity instrument | |
| CN2474570Y (en) | Device for automatic detecting flatness of road surface | |
| CN106940169A (en) | A kind of shafting jacking data acquisition and processing unit | |
| CN108896666A (en) | Bolt cylinder Guided waves system and its detection method | |
| CN104614106B (en) | High-speed railway rail stress detection device | |
| CN105547130A (en) | Method and device for detecting pitch error of ABS ring gear | |
| CN207227503U (en) | A kind of effect of vibration stress relief online rating system based on multiple acceleration transducers information fusion | |
| CN102944255B (en) | Digital optical fiber grating demodulation instrument and method | |
| CN2754052Y (en) | Steel raid straight ness measuring instrument | |
| CN205178985U (en) | Photovoltaic module angle of incidence factor of influence testing arrangement | |
| CN114137470A (en) | Bandwidth testing device and measuring method thereof | |
| CN112078827A (en) | Multifunctional propeller measuring instrument and measuring method | |
| CN112504137B (en) | Multi-target digital image detection method based on cloud computing | |
| CN221649666U (en) | Rapid measuring system for ground water level of homogeneous stratum | |
| CN204649825U (en) | Based on the high speed true effective value rectifying system of FPGA |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20200721 Effective date of abandoning: 20240419 |
|
| AV01 | Patent right actively abandoned |
Granted publication date: 20200721 Effective date of abandoning: 20240419 |