A test device and a multi-physical field measurement method for in-pipe gas-liquid two-phase jet condensation

Abstract

The application provides a kind of in-pipe gas-liquid two-phase jet condensation test device and multi-physical field measurement method, in the test device, water storage tank, frequency conversion pump, solenoid valve, mass flowmeter, heater, visual test section are sequentially connected along the medium flow direction;The outlet of visual test section is sequentially connected condenser, solenoid valve and water storage tank, the outlet of heater, the outlet of visual test section and the outlet of solenoid valve are all provided with pressure sensor and thermocouple;Deionized water tank, electric heating boiler, regulating valve, vortex flowmeter and visual test section are sequentially connected along the medium flow direction, pressure sensor and thermocouple are provided at the outlet of vortex flowmeter, steam nozzle, pressure sensor, thermocouple, multiple hydrophones, accelerometer and sound wave generator are provided on visual test section;It can realize the wide range regulation and control of supercooled working medium flow rate and pressure, solve the difficulty of flow rate and pressure regulation and control of static working medium experimental device, and the laboratory reproduction problem of condensation instability mechanism under dynamic working condition.

Description

Technical Field

[0001] This invention belongs to the field of jet heat transfer and heat storage, specifically relating to a test device and a multi-physics field measurement method for gas-liquid two-phase jet condensation inside a pipe. Background Technology

[0002] Direct contact condensation of steam jets in subcooled fluid within a pipe is a highly efficient heat and mass transfer process with near 100% energy utilization. It is considered a core heat and mass transfer solution in energy and nuclear engineering fields such as nuclear reactor thermal-hydraulic systems, high-thrust liquid rocket engine systems, and underwater propulsion systems. This process achieves near-instantaneous energy exchange through the dynamic interaction of the gas-liquid two-phase interface. The rapid release of latent heat of steam and the turbulent mixing of the subcooled liquid jointly drive the intense reorganization of the thermal boundary layer, while the formation and propagation of condensation shock waves further enhance momentum transfer efficiency. Especially in liquid oxygen-kerosene rocket engine systems, the direct contact condensation process of gaseous and liquid oxygen in the liquid oxygen pump pipeline directly affects the efficiency of the high-pressure staged combustion cycle: the condensation rate of gaseous oxygen directly affects the fluid density and pressure pulsation characteristics at the liquid oxygen pump inlet. The sensible and latent heat released during its phase change not only maintains the supercritical thermodynamic state of the turbine working fluid but also ensures the timing matching accuracy of the propellant supply to the combustion chamber by suppressing two-phase flow instability. This complex coupling mechanism, involving multi-scale vortex structures, non-equilibrium thermodynamic responses, and transient interface dynamics, makes this process a key link in ensuring the thrust and reliability of liquid oxygen-kerosene engines. Suppressing condensation oscillation modes and raising the flow instability threshold have become core challenges in the design of advanced propulsion systems.

[0003] However, the intense interphase interaction between the steam jet and the cross-flow subcooled water can induce strong coupling effects of multiple physical fields: 1) The collapse of steam bubbles caused by the instability of the condensation interface will generate transient pressure peaks with amplitudes in the kilopascal range, causing high-frequency mechanical fatigue of the pipeline system; 2) The radiated noise caused by the instability of the gas-liquid interface covers the frequency band of 1-5000Hz, which is prone to resonance with the natural frequency of the pipeline system; 3) The thermal shock load generated by the transient condensation process can cause hydrogen embrittlement failure of the structural materials.

[0004] Current research largely focuses on the condensation characteristics of steam jets in large-space static water environments. However, in actual industrial systems, the subcooled working fluid is generally under forced convection, making it impossible for traditional large-space pool-based research systems to reproduce the shear effect of cross-flow subcooled water on the steam jet, as well as the combined influence of factors such as the Reynolds number of subcooled water and the pressure at the steam injection point on gas-liquid condensation behavior. This leads to increased prediction errors in jet length, condensation noise oscillation frequency, and heat transfer coefficient. Furthermore, existing experimental systems mostly focus on the pressure fluctuation characteristics of the condensation flow field, lacking quantitative characterization methods for condensation-induced noise radiation and structural vibration characteristics.

[0005] Chinese Patent CN114754965A discloses an experimental device for immersing a steam jet containing non-condensable gases and its usage method. This addresses the problems of existing technologies, such as the inability to provide non-condensable gases, the inability to conduct experiments involving direct contact with condensation phenomena, the inability to provide a stable steam jet with a certain flow rate and air content under both high and low flow conditions, and the inability to guarantee sufficient mixing of the two gases and accurate acquisition of flow data. The device designs an experimental apparatus for immersing a steam jet containing non-condensable gases, including an electrically heated boiler, an air compressor, a steam storage tank, an air supply branch, a main transport pipeline, and a visual water tank. Stable mixing and flow control of steam and air are achieved through devices such as vortex flow meters, regulating valves, and thermocouples, ensuring a stable jet under different operating conditions. The focus is on studying the condensation morphology and heat transfer characteristics of the steam jet containing non-condensable gases in an open water tank, solving the problem of uniform gas-steam mixing in static mixers.

[0006] Therefore, there is an urgent need to develop high-parameter experimental devices and multi-physics measurement methods that can accurately simulate the dynamic interaction between cross-flow subcooled water and steam jets. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides an experimental apparatus and multi-physics field measurement method for direct contact condensation of a steam jet in a cross-flow subcooled water stream within a pipe. This method enables wide-range control of the flow rate and pressure of the subcooled working fluid and simultaneously acquires multi-physics field data such as cross-scale gas-liquid interface dynamics, broadband pressure spectrum, acoustic radiation energy field, and structural vibration modes. This solves the difficulties in controlling the flow rate and pressure of static working fluid experimental apparatuses, as well as the challenges of accurate laboratory reproduction and cross-scale synchronous measurement of condensation instability mechanisms under dynamic conditions.

[0008] To achieve the above objectives, in a first aspect, the present invention provides a testing device for condensation of a gas-liquid two-phase jet in a pipe. A water storage tank, a variable frequency pump, a solenoid valve, a mass flow meter, a heater, and a visualization test section are connected sequentially along the medium flow direction. Pressure sensors and thermocouples are installed on the pipeline from the solenoid valve to the mass flow meter and on the pipeline from the heater to the visualization test section. The outlet of the visualization test section is connected sequentially to a condenser, a solenoid valve, and a water storage tank. Pressure sensors and thermocouples are installed on the pipeline from the outlet of the visualization test section to the condenser and on the pipeline from the solenoid valve to the water storage tank. A deionized water tank, an electric heating boiler, a regulating valve, a vortex flow meter, and the visualization test section are connected sequentially along the medium flow direction. Pressure sensors and thermocouples are installed on the pipeline from the vortex flow meter to the visualization test section. The visualization test section is equipped with a steam nozzle, a pressure sensor, a thermocouple, multiple hydrophones, an accelerometer, and a sound wave generator.

[0009] Furthermore, the outlet of the vortex flow meter is connected to the nozzle inlet of the visualization test section; the heater is connected to the subcooled medium flow channel inlet of the visualization test section.

[0010] Furthermore, pressure sensors, thermocouples, mass flow meters, hydrophones, accelerometers, and vortex flow meters are all connected to the data acquisition system.

[0011] Furthermore, the nozzle is connected to the visualization test section via a threaded connection, while the remaining components are connected to the pipeline via flanges.

[0012] Furthermore, the main body of the visualization test section is a rectangular cross-section pressure-resistant cavity made of PC material with a light transmittance of ≥92% and a pressure resistance rating of PN40.

[0013] Furthermore, a pulsed laser, two holographic cameras, a blue laser source, a blue laser beam splitter, and a reflector are set on the outer side of the main body of the visualization test section. A blue laser beam splitter is set on the optical path of the blue laser source, and a reflector is set on one optical path of the blue laser beam splitter. The reflector and the beam splitter are placed parallel to each other, and the beam splitter is at a 45° angle to the rear wall of the visualization test section.

[0014] Furthermore, high-pass filters are installed at the pulsed laser outlet and the microscope head inlet; a low-pass filter is installed at the holographic camera inlet. The low-pass filter makes angles of 45° and 0° with the front and right walls of the visualization test section, respectively. The high-pass filter in front of the pulsed laser makes an angle of 45° with the left wall of the visualization test section, and the high-pass filter in front of the microscope head is parallel to the right wall of the visualization test section.

[0015] Furthermore, the acoustic generator on the visualization test section is used to generate fixed or variable frequency acoustic waves, the hydrophone and pressure sensor are used to capture acoustic and pressure fluctuations during the gas-liquid jet condensation and collapse process, and the accelerometer collects structural vibration information induced by gas-liquid condensation.

[0016] Secondly, the present invention provides a test device for condensing the above-mentioned gas-liquid two-phase jet in a pipe for simulating industrial two-phase flow states, used to simulate the condensation process of two-phase fluids with high pressure, high Reynolds number and unsteady flow characteristics.

[0017] Thirdly, the present invention provides a multi-physics field measurement method for gas-liquid two-phase jet condensation inside a pipe, based on the above-mentioned testing device for gas-liquid two-phase jet condensation inside a pipe, comprising: Adjust the frequency of the variable frequency pump so that the flow velocity of the subcooled medium in the pipe exceeds the target flow velocity. At this time, the solenoid valve is in the fully open state. Gradually reduce the opening of the solenoid valve at the end of the circulation pipeline to gradually reduce the flow rate of the subcooled medium and gradually increase the pressure. Once the flow rate drops to the target value, observe whether the pressure reaches the target value: if it does, the adjustment ends; if it does not, continue to increase the frequency of the variable frequency pump and decrease the opening of the solenoid valve until both the flow rate and pressure reach the target value. Saturated steam is generated by an electric heating boiler. After the flow rate and pressure of the subcooled medium are regulated, the electric heating boiler is turned on. The boiler operates periodically and is turned off when the saturated steam reaches the rated pressure. The mass flow rate of saturated steam is controlled by the nozzle diameter and the regulating valve. The initial steam mass flow rate is set by the opening of the regulating valve. After the opening of the regulating valve is adjusted to the corresponding initial steam mass flow rate, the opening is fixed. The steam is freely released into the visualization test section under the action of the pressure difference between the electric heating boiler and the visualization test section. After the steam is released, the regulating valve, the frequency converter pump and the solenoid valve are closed in sequence.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: The test device for gas-liquid two-phase jet condensation in a pipe provided by the present invention can simulate the actual working process of gas-liquid jet condensation in a confined space in the energy and power industry, filling the gap in gas-liquid two-phase jet condensation experiments in pipes; by adopting a visual flow channel design for the subcooled working fluid and combining it with a high-precision optical system, the dynamic capture of the three-dimensional morphology of the gas-liquid two-phase jet can be realized; by adopting the coordinated control of a variable frequency pump and a solenoid valve, the flow rate and pressure of the subcooled working fluid can be precisely adjusted to meet the experimental requirements of different working conditions; by constructing an optical path system and integrating a holographic camera, microscale particle image velocimetry technology, pressure sensor, hydrophone and accelerometer, a multi-parameter coupled synchronous measurement system is constructed to realize cross-scale synchronous measurement of the gas-liquid jet condensation phase interface, jet condensation velocity field, pressure field, sound field and structural vibration. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a test device system for gas-liquid two-phase jet condensation inside a tube according to the present invention. Figure 2 This is a schematic diagram of a visual test section of a test device for gas-liquid two-phase jet condensation in a pipe according to the present invention. Figure 3 This is a top view of the test section of a test device for gas-liquid two-phase jet condensation in a pipe according to the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "one side", "one end", "side", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Reference Figure 1 As shown, a test device for condensation of gas-liquid two-phase jet in a pipe includes a water tank 1, a variable frequency pump 2, a solenoid valve 3, a pressure sensor 4, a thermocouple 5, a mass flow meter 6, a heater 7, a visualization test section 8, a nozzle 9, a hydrophone 10, an accelerometer 11, a sound wave generator 12, a condenser 13, a deionized water tank 14, an electric heating boiler 15, a regulating valve 16, a vortex flow meter 17, a data acquisition system 18, and a computer 19.

[0023] Water storage tank 1, variable frequency pump 2, solenoid valve 3, mass flow meter 6, heater 7, and visual test section 8 are connected sequentially along the medium flow direction. Pressure sensor 4 and thermocouple 5 are installed on the pipeline from solenoid valve 3 to mass flow meter 6 and on the pipeline from heater 7 to visual test section 8. The outlet of visual test section 8 is connected sequentially to condenser 13, solenoid valve 3, and water storage tank 1. Pressure sensor 4 and thermocouple 5 are installed on the pipeline from the outlet of visual test section 8 to condenser 13 and on the pipeline from solenoid valve 3 to water storage tank 1.

[0024] The deionized water tank 14, the electric heating boiler 15, the regulating valve 16, the vortex flow meter 17, and the visualization test section 8 are connected in sequence along the medium flow direction. A pressure sensor 4 and a thermocouple 5 are installed on the pipeline from the vortex flow meter 17 to the visualization test section 8. The outlet of the vortex flow meter 17 is connected to the inlet of the nozzle 9 of the visualization test section 8. The heater 7 is connected to the inlet of the subcooled medium flow channel of the visualization test section 8.

[0025] Pressure sensor 4, thermocouple 5, mass flow meter 6, hydrophone 10, accelerometer 11, and vortex flow meter 17 are all connected to data acquisition system 18, which is connected to computer 19.

[0026] A water storage tank 1 and a variable frequency pump 2 are used to store and supply the subcooled working fluid at variable speeds. A solenoid valve 3 installed on the circulation pipeline is used to regulate the flow rate and pressure of the subcooled working fluid. A heater 7 is used to ensure the temperature of the subcooled working fluid. A pressure sensor 4, a thermocouple 5, and a mass flow meter 6 are used to monitor the pressure, temperature, and flow rate of the subcooled working fluid, respectively. The subcooled working fluid returns to the water storage tank 1 after recovering excess heat through a condenser 13. Except for the pressure sensor 4 and the thermocouple 5, all the above components are connected to the subcooled working fluid circulation pipeline through flanges to ensure sealing and maintainability.

[0027] The purified deionized water is stored in deionized water tank 14. After passing through electric heating boiler 15, it becomes saturated steam. Regulating valve 16 and vortex flow meter 17 are used for steam flow control and monitoring, respectively. In addition, the steam pipeline is covered with an insulation layer to ensure that the steam enters the saturated state of the visualization test section 8 through nozzle 9. Nozzle 9 is connected to visualization test section 8 by threads, and the remaining components are connected to the pipeline by flanges.

[0028] Reference Figure 2 and Figure 3 As shown, the main body 801 of the visualization test section is a rectangular cross-section pressure-resistant cavity made of PC material, 30mm thick, with a light transmittance ≥92% and a pressure resistance rating of PN40. Two holographic cameras 808 are positioned on the front and sides of the main body 801 to capture the condensation behavior of the gas-liquid two-phase jet and reconstruct the spatiotemporal evolution characteristics of the three-dimensional gas-liquid interface. A blue laser with a wavelength of 473nm emitted by a blue laser source 803 is split into two beams by a beam splitter 806, which forms a 45° angle with the rear wall of the visualization test section 8. One beam is directed towards the holographic camera 808 on the front of the visualization test section 8, while the other beam is reflected by a reflector 805 to the holographic camera 808 on the side of the visualization test section 8. The reflector 805 is placed parallel to the beam splitter 806. The holographic camera 808 is equipped with low-pass filters 807 at its light inlet to ensure that only 473nm blue light can enter the lens. The angles between the low-pass filters 807 and the front and right walls of the visualization test section 8 are 45° and 0°, respectively. The micro-PIV system 809 is used to analyze the turbulent vortex structure of the gas-liquid jet condensation flow field. Its background light source is emitted by a 532nm pulsed laser 802. The tracer particles are 0.5μm fluorescent particles, which generate 610nm red light after excitation. A high-pass filter 804 is set at the microscope head light inlet to ensure that red light enters the camera for imaging. The high-pass filter 804 in front of the laser is at a 45° angle to the left wall of the visualization test section 8, while the high-pass filter 804 in front of the microscope head is parallel to the right wall of the visualization test section 8. In addition, the relative positions of all lenses, lasers, and optical lenses need to be adjusted according to the size and quality of the required flow field image.

[0029] From bottom to top, the wall of the visualization test section 8 is equipped with a steam nozzle 9, a pressure sensor 4, a thermocouple 5, multiple hydrophones 10, an accelerometer 11, and a sound generator 12. The sound generator 12 is used to generate fixed or variable frequency sound waves. The hydrophones 10 and the pressure sensor 4 are used to capture sound waves and pressure fluctuations during the condensation and collapse process of the gas-liquid jet. The accelerometer 11 collects structural vibration information induced by gas-liquid condensation. The synchronous trigger ensures cross-scale synchronous measurement of the dynamic behavior of the gas-liquid interface, pressure spectrum, sound field, and vibration modes. The experimental data is transmitted to the computer 19 via the data acquisition system 18. The hydrophone 10 is a high-frequency hydrophone.

[0030] Before each experiment, turn on the frequency converter pump 2 and the solenoid valve 3 to allow the supercooled liquid to circulate in the pipeline, so as to prevent damage to the components due to the lack of cooling medium when steam is injected into the visualization test section 8.

[0031] The flow rate and pressure of the subcooled medium need to be adjusted synchronously: First, adjust the frequency of the variable frequency pump 2 so that the flow rate of the subcooled medium in the pipe is slightly greater than the target flow rate. At this time, the solenoid valve 3 is in the fully open state.

[0032] Secondly, gradually reduce the opening of solenoid valve 3 at the end of the circulation pipeline to gradually decrease the flow rate of the subcooled medium and gradually increase the pressure. Finally, once the flow rate drops to the target value, observe whether the pressure reaches the target value: if it does, the adjustment is complete. If it does not, continue to increase the frequency of variable frequency pump 2 and decrease the opening of solenoid valve 3 until both the flow rate and pressure reach the target values.

[0033] Saturated steam is generated by an electrically heated boiler 15. After the flow rate and pressure of the subcooled medium are regulated, the electrically heated boiler 15 is turned on. The boiler 15 operates periodically and is turned off when the saturated steam reaches the rated pressure to prevent continuous steam production.

[0034] The main saturated steam parameter of interest in the experiment was the mass flow rate, which was controlled by the diameter of nozzle 9 and the opening of regulating valve 16. When the diameter of nozzle 9 and the opening of regulating valve 16 were fixed, a specific mass flow rate was determined for saturated steam at a specific temperature and pressure. Since the diameter of nozzle 9 was fixed for each experiment, the initial steam mass flow rate was mainly set by adjusting the opening of regulating valve 16.

[0035] After the opening of regulating valve 16 is adjusted to the corresponding initial steam mass flow rate, its opening is kept constant. The steam is then freely released into the visual test section 8 under the pressure difference between the electric heating boiler 15 and the visual test section 8. After the steam release is complete, regulating valve 16, variable frequency pump 2, and solenoid valve 3 are closed in sequence, and the experiment ends.

[0036] In summary, the test device for condensation of gas-liquid two-phase jets inside a pipe provided by this invention can simulate the actual working process of gas-liquid jet condensation in confined spaces within pipes in the energy and power industry. Through a modular flow channel structure and a multi-media compatible sealing system, this device can reproduce the high-pressure, high-Reynolds-number, and unsteady-state flow characteristics in typical industrial scenarios such as secondary-side steam injection in nuclear reactors and mixing of liquid rocket propellants in pipelines, filling the gap in experiments on condensation of gas-liquid two-phase jets inside pipes. Its innovative segmented temperature-pressure decoupling control strategy allows the experimental section to maintain a precise gradient distribution of supercooling while independently adjusting the local saturated vapor pressure, providing controllable boundary conditions for studying the evolution of condensation modes during the transition from subcritical to supercritical states. Furthermore, by employing a visual flow channel design for the supercooled working fluid, combined with a high-precision optical system, the dynamic capture of the three-dimensional morphology of the gas-liquid two-phase jet is achieved. The flow channel body employs a refractive index matching technology integrated with a pressure-resistant optical window scheme. By eliminating the refractive index difference between the multiphase flow medium and the transparent material, it significantly reduces laser scattering distortion caused by the high-speed gas-liquid interface. Equipped with a dual-wavelength pulsed laser source and a high-speed framing camera coupling system, combined with laser-induced fluorescence (LIF) and background schlieren (BOS) composite measurement methods, it can simultaneously track the topological evolution of the vapor jet cavitation structure, the microscale fluctuations of the subcooled liquid film, and the three-dimensional spatiotemporal characteristics of condensation shock wave propagation. Through the coordinated control of a variable frequency pump and solenoid valves, the flow rate and pressure of the subcooled working fluid are precisely adjusted. A fluid parameter dynamic control system based on a PID-PWM composite control algorithm can generate unsteady flow conditions such as step, ramp, and sinusoidal disturbances, effectively simulating transient condensation behavior during rocket engine thrust regulation or nuclear power plant load transients. The closed-loop feedback system automatically compensates for local temperature abrupt changes caused by the release of latent heat of phase change by real-time analysis of the flow field characteristic parameters acquired by multispectral sensors, ensuring that the fluid thermodynamic state evolves along a predetermined trajectory. By constructing an optical path system and integrating a holographic camera, micro-PIV (microscale particle image velocimetry), pressure sensor, hydrophone, and triaxial accelerometer, a multi-parameter coupled synchronous measurement system was built. This device innovatively employs a beam splitter array and timestamp synchronization triggering technology to achieve nanosecond-level precision cross-physics field data fusion: the holographic camera captures micrometer-level phase interface fluctuation characteristics, the micro-PIV analyzes the vortex transport law in the jet core region, the high-frequency pressure sensor and hydrophone quantify the spectral characteristics of condensation shock wave pressure pulsation and cavitation noise characteristic spectrum, respectively, and the triaxial accelerometer extracts the time-frequency coupled modes of pipeline structure vibration and condensation oscillation through dynamic mode decomposition (DMD) algorithm. This multi-dimensional, cross-scale synchronous measurement capability provides a systematic experimental research device and method for revealing key scientific issues such as the phase interface instability mechanism and the interaction law between condensation shock waves and vortex structures during gas-liquid jet condensation.

[0037] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A test device for gas-liquid two-phase jet condensation inside a tube, characterized in that, The water storage tank (1), variable frequency pump (2), solenoid valve (3), mass flow meter (6), heater (7), and visualization test section (8) are connected sequentially along the medium flow direction. Pressure sensor (4) and thermocouple (5) are installed on the pipeline from solenoid valve (3) to mass flow meter (6) and on the pipeline from heater (7) to visualization test section (8). The outlet of visualization test section (8) is connected sequentially to condenser (13), solenoid valve (3), and water storage tank (1). The pipeline from the outlet of visualization test section (8) to condenser (13) and solenoid valve (3) are also connected. Pressure sensors (4) and thermocouples (5) are installed on the pipelines leading to the water storage tank (1); the deionized water tank (14), the electric heating boiler (15), the regulating valve (16), the vortex flow meter (17), and the visualization test section (8) are connected sequentially along the medium flow direction. Pressure sensors (4) and thermocouples (5) are installed on the pipelines from the vortex flow meter (17) to the visualization test section (8). The visualization test section (8) is equipped with a steam nozzle (9), a pressure sensor (4), a thermocouple (5), multiple hydrophones (10), and an accelerometer (11). And a sound wave generator (12); a pulsed laser (802), two holographic cameras (808), a blue laser source (803), a blue laser beam splitter (806), and a reflector (805) are set on the outside of the main body (801) of the visualization test section; a blue laser beam splitter (806) is set on the optical path of the blue laser source (803), and a reflector (805) is set on one optical path of the blue laser beam splitter (806). The reflector (805) and the beam splitter (806) are placed parallel to each other. The beam splitter (806) and the visualization test section are set on the outside of the main body (801) of the visualization test section. The rear wall of segment (8) is at an angle of 45°; a high-pass filter (804) is set at the exit of the pulsed laser (802) and the inlet of the microscope head; a low-pass filter (807) is set at the inlet of the holographic camera (808). The angles between the low-pass filter (807) and the front and right walls of the visualization test segment (8) are 45° and 0°, respectively. The high-pass filter (804) in front of the pulsed laser (802) is at an angle of 45° with the left wall of the visualization test segment (8). The high-pass filter (804) in front of the microscope head is parallel to the right wall of the visualization test segment (8).

2. The testing device for gas-liquid two-phase jet condensation in a pipe according to claim 1, characterized in that, The outlet of the vortex flow meter (17) is connected to the nozzle (9) inlet of the visualization test section (8); the heater (7) is connected to the inlet of the subcooled medium flow channel of the visualization test section (8).

3. The testing device for gas-liquid two-phase jet condensation in a pipe according to claim 1, characterized in that, Pressure sensor (4), thermocouple (5), mass flow meter (6), hydrophone (10), accelerometer (11), and vortex flow meter (17) are all connected to the data acquisition system (18).

4. The testing device for gas-liquid two-phase jet condensation in a pipe according to claim 1, characterized in that, The nozzle (9) is connected to the visualization test section (8) by a thread, and the remaining components are connected to the pipe by a flange.

5. The testing device for gas-liquid two-phase jet condensation in a pipe according to claim 1, characterized in that, The main body of the visualization test section (801) is a rectangular cross-section pressure-resistant cavity made of PC with a light transmittance of ≥92% and a pressure resistance rating of PN40.

6. The testing device for gas-liquid two-phase jet condensation in a pipe according to claim 1, characterized in that, The acoustic generator (12) on the visualization test section (8) is used to generate fixed or variable frequency acoustic waves, the hydrophone (10) and the pressure sensor (4) are used to capture acoustic waves and pressure fluctuations during the gas-liquid jet condensation collapse process, and the accelerometer (11) collects structural vibration information induced by gas-liquid condensation.

7. The application of the test apparatus for condensation of gas-liquid two-phase jet in a pipe according to any one of claims 1-6 in simulating industrial two-phase flow patterns, characterized in that, Simulate the condensation process of a two-phase fluid under high pressure, high Reynolds number, and unsteady flow characteristics.

8. A multi-physics field measurement method for gas-liquid two-phase jet condensation inside a pipe, characterized in that, The test apparatus for condensation of gas-liquid two-phase jet in a tube according to any one of claims 1-7 includes: Adjust the frequency of the variable frequency pump (2) so that the flow velocity of the subcooled medium in the pipe exceeds the target flow velocity. At this time, the solenoid valve (3) is in the fully open state. Gradually reduce the opening of the solenoid valve (3) at the end of the circulation pipeline to gradually reduce the flow rate of the subcooled medium and gradually increase the pressure; Once the flow rate drops to the target value, observe whether the pressure reaches the target value: if it does, the adjustment ends; if it does not, continue to increase the frequency of the variable frequency pump (2) and decrease the opening of the solenoid valve (3) until both the flow rate and pressure reach the target value. Saturated steam is generated by an electric heating boiler (15). After the flow rate and pressure of the subcooled medium are regulated, the electric heating boiler (15) is turned on. The boiler (15) operates periodically and is turned off when the saturated steam reaches the rated pressure. The mass flow rate of saturated steam is controlled by the diameter of the nozzle (9) and the regulating valve (16). The initial steam mass flow rate is set by the opening of the regulating valve (16). After the opening of the regulating valve (16) is adjusted to the corresponding initial steam mass flow rate, its opening is fixed. The steam is freely released into the visualization test section (8) under the action of the pressure difference between the electric heating boiler (15) and the visualization test section (8). After the steam is released, the regulating valve (16), the frequency converter pump (2) and the solenoid valve (3) are closed in sequence.

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