CN114659750A - Multi-physical-field synchronous trigger device measuring system for low-temperature cavitation - Google Patents
Multi-physical-field synchronous trigger device measuring system for low-temperature cavitation Download PDFInfo
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- 239000007788 liquid Substances 0.000 claims abstract description 17
- 238000002474 experimental method Methods 0.000 claims abstract description 14
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Abstract
The invention belongs to the field of fluid machinery. The purpose is to provide a multi-physical field synchronous trigger device measuring system for low-temperature cavitation; the system can acquire a pressure field, a temperature field and a flow field at the same time, and can trigger measurement of the flow field at the same time through the pressure value at the moment when the pressure reaches a certain value; and has the characteristic of high signal quality. The technical scheme is as follows: a multi-physical-field synchronous trigger device measuring system for low-temperature cavitation is characterized in that: the system comprises a synchronous trigger system, a visualization system and a temperature and pressure measuring system which are arranged on an experiment table, wherein a trigger signal of the synchronous trigger system is simultaneously sent to the visualization system and the temperature and pressure measuring system, so that the measurement work is started, and the measurement of triggering the visualization system by a pressure value measured by the pressure measuring system is carried out; the visualization system comprises a cold light lamp for irradiating light rays to a test section in the experiment table and a high-speed camera for shooting a low-temperature liquid flow image to the test section.
Description
Technical Field
The invention belongs to the field of fluid machinery, and particularly relates to a multi-physical-field synchronous trigger device measuring system for low-temperature cavitation.
Background
The cavitation phenomenon is a basic problem causing the failure of the cryogenic pump, and the simultaneous measurement and visualization research of multiple physical fields at the same time is helpful for the deep research of the unsteady cavitation characteristic of the cryogenic fluid. The synchronization method can be divided into software synchronization or hardware synchronization, wherein the software synchronization mode has high requirement on real-time performance, the requirement instruction can be accepted by a plurality of acquisition cards and immediately responds, in reality, the synchronization can only achieve subtle synchronization, the time precision is not high, and the hardware synchronization is to output a synchronization trigger pulse to each acquisition card through a circuit and start the acquisition when the rising edge of a synchronization pulse signal reaches, so the hardware synchronization mode has high precision.
Disclosure of Invention
The invention aims to overcome the defects of the background technology and provide a measuring system of a multi-physical-field synchronous trigger device for low-temperature cavitation; the system can acquire a pressure field, a temperature field and a flow field at the same time, and can trigger measurement of the flow field at the same time through the pressure value at the moment when the pressure reaches a certain value; and has the characteristic of high signal quality.
The technical scheme provided by the invention is as follows: a multi-physical-field synchronous trigger device measuring system for low-temperature cavitation is characterized in that: the system comprises a synchronous trigger system, a visualization system and a temperature and pressure measuring system which are arranged on an experiment table, wherein a trigger signal of the synchronous trigger system is simultaneously sent to the visualization system and the temperature and pressure measuring system, so that the measurement work is started, and the pressure value measured by the pressure measuring system triggers the visualization system to measure;
the visualization system comprises a cold light lamp for irradiating light rays to a test section in the experiment table and a high-speed camera for shooting a low-temperature liquid flow image to the test section;
the temperature and pressure measuring system comprises a low-temperature pressure sensor and a temperature sensor which are respectively arranged on a test section in the experiment table, a signal processor for processing signals acquired by the low-temperature pressure sensor and the temperature sensor, a data acquisition card for acquiring the signals, a signal generator and a computer.
The synchronous triggering system comprises a signal generating circuit for triggering signals, a signal conditioning circuit and a signal verification circuit which are used for receiving and processing output signals of the signal generating circuit at the same time, and a signal driving circuit which is used for receiving and processing the output signals of the signal conditioning circuit and then transmitting the output signals to the high-speed camera, wherein the signal verification circuit is used for verifying whether the output signals of the signal generating circuit are correct.
The experiment table comprises a test section provided with a low-temperature driving machine, a liquid supply tank communicated with the test section through a double-layer pipeline, and a vertical liquid collecting tank communicated with the low-temperature driving machine through a pipeline with a switch valve; the liquid supply tank is provided with a first vacuum pump interface and valve, a compressor interface and valve, and the double-layer pipeline is provided with a horizontal liquid supply tank valve, an isothermal gas inlet, a flowmeter, an isothermal gas outlet, a second vacuum pump interface and valve.
The invention has the beneficial effects that: the synchronous triggering subsystem of the invention is applied to a hardware circuit, and the response time can reach nanosecond. The photoelectric coupler in the signal generating circuit 24 transmits an electric signal by taking light as a medium, the input electric signal drives the light emitting diode to emit light with a certain wavelength, the light emitting diode is received by the optical detector to generate a photocurrent, the photocurrent is further amplified and then output, the input and output electric signals are well isolated, and the electric insulation and anti-interference capability are greatly enhanced. In the signal conditioning circuit 25, the output pulse width (T-C1R 9) is set to be larger than the noise width and smaller than the input signal pulse width, so that the purpose of noise removal is achieved, and the signal quality is high. The signal driving circuit 26 adopts an OCL complementary power amplifying circuit (fully symmetric circuit), a power supply VCC is added, the maximum amplifying power can reach Pom ═ VCC ^2/2RL, and the power of the required driving device can be met according to the values of VCC and RL. The signal verification circuit can verify whether the output signal of the signal generation circuit is correct.
Drawings
FIG. 1 is a schematic diagram of a multiphysics field-synchronous measurement system for cryogenic cavitation in example 1.
Fig. 2 is a circuit diagram of the synchronous measurement system in embodiment 1.
Fig. 3 is a wiring diagram of the device and the synchronous measurement subsystem circuit in the first measurement mode in embodiment 1.
Fig. 4 is a wiring diagram of the device and the synchronous measurement subsystem circuit of the second measurement mode in embodiment 1.
FIG. 5 is a flowchart of the operation of example 1.
Detailed Description
The invention will be described in further detail with reference to embodiments shown in the drawings, in which:
the multi-physical-field synchronous triggering device measuring system for low-temperature cavitation shown in the drawing comprises a synchronous triggering system (namely, a synchronous triggering subsystem in fig. 5) 13, a visualization system (namely, a visualization subsystem in fig. 5) and a pressure and temperature measuring system (namely, a pressure and temperature measuring subsystem in fig. 5) which are arranged on a laboratory bench; the signal triggered by the synchronous triggering system is simultaneously sent to the visualization system and the temperature and pressure measuring system, so that the measurement work is started, and the pressure value measured by the pressure measuring system triggers the measurement of the visualization system.
In the laboratory bench (prior art): a low-temperature driving machine 18 is arranged below the test section 9, the liquid supply tank 1 is communicated with the test section 9 (provided with a transparent shell to facilitate observation and shooting outside the equipment) through a double-layer pipeline 16, and the vertical liquid collection tank 22 is communicated with the low-temperature driving machine through a pipeline with a switch valve 23; the liquid supply tank is provided with a first vacuum pump interface and valve 2, a compressor interface and valve 3, and the double-layer pipeline 16 is provided with a horizontal liquid supply tank valve 4, an isothermal gas inlet 5, a flowmeter 6, an isothermal gas outlet 7 and a second vacuum pump interface and valve 8.
The shooting system comprises a cold light lamp 17 and a high-speed camera 11; the cold light lamp irradiates light to the test section in the experiment table, provides an environment with clear illumination, and is favorable for the high-speed camera to shoot high-quality low-temperature liquid flowing images to the test section.
In the temperature and pressure measuring system, a low-temperature pressure sensor 10 and a temperature sensor 19 are respectively installed on a test section in a test bench, a signal processor 20 is sequentially connected in series with a data acquisition card 14, a signal generator 12 and a computer 15, and signals acquired by the low-temperature pressure sensor 10 and the temperature sensor 1 are sequentially transmitted to the data acquisition card, the signal generator and the computer.
The synchronous trigger system (see fig. 2) includes a signal generating circuit 24 for generating a trigger signal, a signal conditioning circuit (i.e., the conditioning circuit in fig. 2) for simultaneously receiving and processing an output signal of the signal generating circuit, and a signal verifying circuit (i.e., the verifying circuit in fig. 2), and a signal driving circuit (i.e., the driving circuit in fig. 2) for receiving and processing an output signal of the conditioning circuit and then transmitting the output signal to the high-speed camera, where the verifying circuit is used to verify whether the output signal of the signal generating circuit is correct.
The signal generating circuit comprises a resistor R1, a single-pole double-set switch S, a switch button T, a resistor R2, a resistor R3, a first field effect transistor Q1, a photoelectric coupler, a resistor R4, a resistor R5 and two NOT gates; the left end of the resistor R1 is grounded, the right end of the resistor R1 is connected with a first input end IN1 of a single-pole double-position switch S, a switch button T and a resistor R2 IN sequence and then is connected with an A port of a photoelectric coupler, the output end of the single-pole double-position switch S is connected with a resistor R3 and a first field effect transistor Q1 IN sequence and then is connected with a K port of the photoelectric coupler, and a C port of the photoelectric coupler is connected with one end of a resistor R5 and two NOT gates IN sequence and then serves as the output end of a signal generating circuit; the E port of the photoelectric coupler is grounded through a resistor R4; the third port of the first field effect transistor Q1 is vacant, and the second input end IN2 of the single-pole double-position switch S is also vacant; the common terminal (VCC) of the signal generating circuit is connected between the switch button T and the resistor R2 and the other terminal of R5.
The signal conditioning circuit 25 includes a resistor R9, a resistor R10, a capacitor C1, and a first stable flip-flop 1 (i.e., stable flip-flop 1 in fig. 2). One end of the resistor R9 is connected with the capacitor C1 in series and then connected with the CX port of the first steady-state trigger, one end of the resistor R9 is also connected with the RX/CX port of the first steady-state trigger, and the other end of the resistor R9 is connected with the common terminal VCC. The port A of the first steady state trigger is grounded, and the port B of the first steady state trigger is connected with the output end of the signal generating circuit; the resistor R10 is connected in series between the common terminal VCC and the MR port of the first steady state flip-flop, and the Q terminal (output terminal) of the first steady state flip-flop is connected with the input terminal of the signal driving circuit.
The signal driving circuit 26 comprises two triodes Q2 and Q3 and a load resistor RL. The two triodes Q2 and Q3 are symmetrically arranged, and the base electrodes of the two triodes are connected with the output end of the signal conditioning circuit; the collector electrodes of the two triodes are connected with a common terminal VCC, and the other collector electrode is connected with a common terminal VCC; and the emitting electrodes of the two triodes are connected and then used as the output end OUT of the synchronous triggering system. One end of the load resistor RL is connected to the output terminal OUT, and the other end is grounded.
The signal verification circuit 27 includes a resistor R6, a resistor R7, a capacitor C2, a second stable flip-flop 2 (i.e., the stable flip-flop 2 in fig. 2), a resistor R8, a second field effect transistor Q2, and a light emitting diode D. One end of a resistor R6 is connected with a CX port of the second stable trigger 2 through a capacitor C2, one end of a resistor R6 is also connected with an RX/CX port of the second stable trigger, the other end of the resistor R6 is connected with an MR port of the second stable trigger through a resistor R7, and a connecting line between the resistor R6 and the resistor R7 is also connected with a common terminal VCC; the A port of the second steady state trigger is grounded, and the B port of the second steady state trigger is also connected with the output end of the signal generating circuit. The Q end (output end) of the second steady-state trigger 1 is connected with the input port of a second field effect transistor Q2; the second port of the second field effect transistor Q2 is connected with the common terminal VCC through a resistor R8; the third port of the second field effect transistor Q2 is connected to ground through the light emitting diode D.
The working process is shown in fig. 3, 4 and 5.
1. When the flow field, the pressure field and the temperature field are measured simultaneously, as shown in fig. 3:
after vacuumizing and precooling, when the pipeline is filled with low-temperature liquid, a low-temperature driving motor is started to generate low-temperature cavitation flow in the flow channel. The shooting system and the temperature and pressure measuring system are in a waiting triggering state, and the acquisition frequency and the acquisition time length of the temperature and pressure measuring and visualization system are set. At this time, the single-pole double-set switch S IN the synchronous trigger system signal generating circuit 24 is connected with the port IN1, and the acquisition card 14 IN the temperature and pressure measuring system and the high-speed camera 11 IN the shooting subsystem are connected with the out end of the signal driving circuit 26 IN the synchronous trigger system. When the measured working condition is stable, a button T of a signal generating circuit 24 in the synchronous trigger system is pressed to generate a high-level pulse signal, the signal passes through a photoelectric coupler and simultaneously reaches a port B of a first stable trigger 1 and a port B of a second stable trigger 2, the signal passing through the first stable trigger 1 is amplified in power by a signal driving circuit 26, and a synchronous trigger pulse is output at an OUT port of the driving circuit and is transmitted to temperature measurement and pressure measurement to be synchronously measured; when the second stable trigger 2 receives the pulse, the diode will flash to prove that the signal is transmitted without errors. The data acquisition card (acquiring temperature and pressure signals) and the high-speed camera start to work, and image information and pressure and temperature pulsation signals are stored in a connected computer, so that multi-field synchronous acquisition and analysis are completed, and the test is finished.
2. When the pressure reaches a certain value, a measurement experiment of the flow field at the same moment is triggered, as shown in fig. 4:
the earlier operation is the same as the earlier operation IN fig. 1, and if the pressure is required to reach a certain value to trigger the measurement of the flow field, at this time, the single-pole double-position switch of the signal generating circuit 24 IN the synchronous triggering system is connected to the IN2 port, and the signal generator 12 adopts a voltage output type DA converter (the model can be selected as TLC5620), so that the digital value can be converted into a pulse signal. When the pressure reaches a certain value, the internal circuit of the signal generator 12 will generate a high level signal and convert it into a pulse signal to be transmitted to the IN2 port; and the trigger value of the pressure can be set by changing a slide rheostat inside the signal generator. The OUT port of the signal driving circuit 26 is connected with the high-speed camera 11 in the synchronous triggering system, shooting is carried OUT after the driving signal is received, and when the steady-state trigger 2 in the verification circuit 27 receives the pulse, the diode flickers to prove that the signal is transmitted without errors. This measurement can measure cavitation collapse occurring in the flow field. The measuring device starts to measure and stores the image information to a connected computer, so that the measurement experiment of the high-speed camera triggered by pressure is completed, and the experiment is finished.
The time precision of the synchronous measurement technology used by the invention is higher than that of a software control technology, different experimental measurement requirements can be met by changing a wiring mode, a detection circuit is arranged for synchronous trigger signals to verify the transmission efficiency of the signals, phenomena such as cavitation rupture and the like can be observed, and the influence of temperature and pressure on low-temperature cavitation at the same moment can be known more comprehensively.
The synchronous triggering system of the invention is applied to a hardware circuit, and the response time can reach nanosecond. The photoelectric coupler in the signal generating circuit transmits an electric signal by taking light as a medium, the input electric signal drives the light emitting diode to emit light with a certain wavelength, the light emitting diode is received by the optical detector to generate a photocurrent, the photocurrent is further amplified and then output, the photoelectric coupler has a good isolation effect on the input and output electric signals, and the electric insulation and anti-interference capability is greatly enhanced. The signal conditioning circuit achieves the aim of removing noise by setting the output pulse width (T-C1R 9) to be more than the noise width and less than the input signal pulse width, and the signal quality is high. The driving circuit adopts an OCL complementary power amplifying circuit (a full-symmetrical circuit), a power supply VCC is additionally arranged, the maximum amplifying power can reach Pom ═ Vcc ^2/2RL, and the power of the required driving equipment can be met according to the values of VCC and RL.
Claims (5)
1. A multi-physical-field synchronous trigger device measuring system for low-temperature cavitation is characterized in that: the system comprises a synchronous trigger system (13), a visualization system and a temperature and pressure measuring system which are installed on an experiment table, wherein a trigger signal of the synchronous trigger system is simultaneously sent to the visualization system and the temperature and pressure measuring system, so that the measurement work is started, and the pressure value measured by the pressure measuring system triggers the visualization system to measure.
2. The multi-physical-field synchronized trigger device measurement system for cryogenic cavitation of claim 1, wherein: the visualization system comprises a cold light lamp (17) for irradiating light rays to a test section in the experiment table and a high-speed camera (11) for shooting a low-temperature liquid flow image to the test section.
3. The multi-physics field synchronized trigger device measurement system for cryogenic cavitation of claim 2 wherein: the temperature and pressure measuring system comprises a low-temperature pressure sensor (10), a temperature sensor (19), a signal processor (20), a data acquisition card (14), a signal generator (12) and a computer (15), wherein the low-temperature pressure sensor and the temperature sensor are respectively arranged on a test section in the experiment table, and the signal processor (20) is used for processing signals acquired by the low-temperature pressure sensor and the temperature sensor and is used for acquiring signals.
4. The multi-physical-field synchronized trigger device measurement system for cryogenic cavitation of claim 3, wherein: the synchronous trigger system comprises a signal generating circuit (24) for triggering signals, a signal conditioning circuit (25) for simultaneously receiving and processing output signals of the signal generating circuit, a signal verification circuit and a signal driving circuit (26) for receiving and processing the output signals of the conditioning circuit and then transmitting the output signals to the high-speed camera, wherein the signal verification circuit is used for verifying whether the output signals of the signal generating circuit are correct.
5. The multi-physical-field synchronized trigger device measurement system for cryogenic cavitation of claim 4, wherein: the experiment table comprises a test section (9) provided with a low-temperature driving machine (18), a liquid supply tank (1) communicated with the test section through a double-layer pipeline (16), and a vertical liquid collection tank (22) communicated with the low-temperature driving machine through a pipeline with a switch valve (23); the liquid supply tank is provided with a first vacuum pump interface and valve (2), a compressor interface and valve (3), and the double-layer pipeline is provided with a horizontal liquid supply tank valve (4), an isothermal gas inlet (5), a flowmeter (6), an isothermal gas outlet (7), a second vacuum pump interface and valve (8).
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115898854A (en) * | 2023-01-06 | 2023-04-04 | 山东省科学院能源研究所 | Visual experimental system of ocean LNG cold energy recovery pump cavitation |
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