Cavitation and cavitation erosion experiment table for low-temperature pipeline

Abstract

A low-temperature pipeline cavitation and cavitation erosion experiment table disclosed by the present invention comprises a liquid supply tank, a venturi tube assembly and a receiving tank, the venturi tube assembly comprises a venturi tube, a test piece mounting seat and a plurality of sensors, one end of the venturi tube assembly is communicated with the liquid supply tank, the other end of the venturi tube assembly is communicated with the receiving tank, and the cross section of a flow channel of the venturi tube is rectangular. An embedding groove and a plurality of sensor mounting grooves are formed in the flow channel wall of the venturi tube; the test-piece mounting seat is used for fixing a test-piece; the plurality of sensors comprise a vibration sensor, a temperature sensor and a pressure sensor, and the vibration sensor is arranged on the test piece mounting seat; the temperature sensor and the pressure sensor are respectively embedded in the corresponding sensor mounting grooves; by adopting the design of the venturi tube with the rectangular section, the space adaptability and the experiment controllability are remarkably improved. The test piece and various sensors are arranged along the venturi tube, so that the accurate association between the material cavitation damage and the multi-physical field signal is realized, the cavitation collapse transient process is accurately captured, and the reliability of experimental data is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of cavitation and erosion of hydrogen energy aircraft pipelines and cryogenic liquid storage and transportation pipeline systems, in particular to a cryogenic pipeline cavitation and erosion test bench. Background Art

[0002] Cavitation is the formation of bubbles in a liquid due to reduced pressure. These bubbles quickly collapse in high-pressure areas, generating a strong shock wave that damages surrounding materials. This is known as cavitation erosion. In liquid rocket engines, cavitation is particularly severe within the piping because rocket fuel (such as liquid hydrogen) has a high vapor pressure and low boiling point at low temperatures, making it more susceptible to bubble formation. Cavitation not only affects engine performance but can also lead to unstable engine thrust and even cause engine failure.

[0003] Cryogenic fluid systems, in particular, are prone to cavitation and erosion, which affects system performance and life. At low temperatures (such as liquid hydrogen, liquid nitrogen, etc.), the saturated vapor pressure of the fluid is extremely low. However, if the local pressure drops below the saturated vapor pressure due to flow disturbances (such as valve throttling, insufficient pump inlet pressure), cavitation (bubble formation and collapse) is very likely to occur. The surface tension and viscosity of cryogenic fluids are usually low, making bubbles easier to generate and less stable. The microjets and shock waves generated when they collapse are more intense, exacerbating cavitation damage. By using a typical cavitation-generating structure such as a Venturi tube to study the mechanism of cryogenic liquid storage and transportation pipeline systems, it can assist staff in gaining an in-depth understanding of the cryogenic cavitation mechanism, help reveal the behavioral characteristics of cryogenic media under specific working conditions, and provide a scientific basis for the optimized design of hydrogen aircraft pipelines and cryogenic liquid storage and transportation pipeline systems.

[0004] Currently, research on cavitation in venturi tubes focuses primarily on experimental observation, numerical simulation, and theoretical analysis. Specifically, high-speed photography and pressure sensors are used to observe the flow and cavitation phenomena within the venturi tube. Computational fluid dynamics (CFD) techniques are used to simulate the flow and cavitation processes within the venturi tube, establish mathematical models of cavitation and erosion, and predict the trend and extent of cavitation erosion. However, the unique physical properties of cryogenic liquids complicate the cavitation process, and the dynamic behavior and collapse mechanism of cavitation bubbles are not fully understood. Existing experimental platforms can only analyze and predict the trend and extent of cavitation by observing images within the venturi tube and recording pressure and temperature. It is difficult to combine the microscopic morphology of the specimen surface with the vibration signal of the specimen material to analyze the transient signal when the material is subjected to cavitation damage. Summary of the Invention

[0005] The purpose of the present invention is to provide a low-temperature pipeline cavitation and erosion test bench to solve the above problems.

[0006] The technical solution of the present invention is:

[0007] The cryogenic pipeline cavitation and erosion test bench includes a liquid supply tank for storing cryogenic liquid, which is conveniently supplied via a quick-cooling device. The tank is equipped with a mass flowmeter to accurately measure the liquid flow rate, ensuring the stability of experimental conditions. Furthermore, the tank is equipped with an electric regulating valve to adjust the liquid supply pressure and flow rate to meet the requirements of different experimental conditions. The venturi tube assembly includes a transparent venturi tube connected to the liquid supply tank at one end, used to generate cavitation. Its internal structure and dimensions can be designed and adjusted according to experimental requirements. The venturi tube has a rectangular flow channel cross-section and is provided with a mounting groove and multiple sensor mounting slots on the wall of the venturi tube. The mounting groove is located in the diverging section of the venturi tube flow channel. A specimen mounting seat is embedded in the mounting groove and has a specimen mounting slot for securing the specimen. The specimens are made of replaceable materials including X52 pipeline steel, 304 stainless steel, 5A05 aluminum alloy, PE63, and PE100. Multiple sensors include: a vibration sensor, which is installed on the specimen mounting seat; a temperature sensor and a pressure sensor, which are respectively embedded in the corresponding sensor mounting slots; the pressure sensor and the temperature sensor are respectively used to monitor the pressure and temperature changes in the experimental pipeline section in real time, providing key parameters for studying the cavitation phenomenon. The vibration sensor is used to detect the vibration signal generated by the specimen during the cavitation process, and further analyze the impact of cavitation on the structure. The receiving tank is used to collect the liquid after passing through the experimental pipeline section, and at the same time perform preliminary separation and treatment of the liquid for subsequent recycling or discharge. The design of the receiving tank takes into account the recovery efficiency and safety of the liquid to ensure the smooth progress of the experimental process.

[0008] Furthermore, two mounting slots are provided, one located in the diverging section of the venturi flow channel, near the middle of the venturi throat. The cross-section of the specimen mounting slot is trapezoidal, and the specimen is a slot with a trapezoidal block structure, which is fixedly inserted into the specimen mounting slot. Two specimen mounting seats are provided because the cavitation cloud detaches at different locations under different cavitation conditions. This allows for more detailed monitoring of the vibration signal caused by the collapse of the cavitation cloud and the damage to the material surface, and facilitates observation of specimen surface damage under an electron microscope.

[0009] Furthermore, one side of the mounting groove of the specimen mounting seat is flush with the flow channel wall of the venturi tube, and the specimen fixed in the mounting groove is flush with the flow channel wall of the venturi tube, ensuring a smooth and stable flow field.

[0010] Furthermore, one end of the inlay groove passes through the side wall of the venturi tube, and a detachable sealing member is provided at the penetration point, so as to facilitate the disassembly and removal of the test piece.

[0011] Furthermore, a groove is provided at the external through-hole of the inlay groove penetrating the side wall of the venturi tube so that the through-hole presents a step-like structure. The sealing member is a sealing plate, a protrusion is connected to the plate surface of the sealing plate, and a sealing ring is provided on the peripheral side of the protrusion to seal the groove. The sealing plate is detachably arranged on the groove.

[0012] Furthermore, one end of the specimen mounting seat protrudes from one end of the inlay groove, and one end of the specimen protrudes from an end surface of one end of the specimen mounting seat. A locking groove is defined on the protrusion of the sealing plate. The locking groove matches the structure of the end surface of the specimen mounting seat and corresponds to the position of the specimen mounting seat, and is used to clamp and secure the specimen mounting seat. Screw holes are defined on the sidewalls of the sealing plate and the venturi tube, and the sealing plate and the venturi tube are secured by screws, so that the protrusion seals the groove and the locking groove on the protrusion secures the specimen mounting seat.

[0013] Furthermore, the sensor mounting groove and the sensor are fixed by sealant.

[0014] Furthermore, there are four pressure sensors, which are arranged in sequence at the middle of the throat of the venturi tube, 15mm, 36mm and 48mm from the middle of the throat of the divergent section; there are three temperature sensors, which are arranged in sequence at 12.5mm from the middle of the throat of the convergent section of the venturi tube, the middle of the throat, and 60mm from the middle of the throat of the divergent section; there are two vibration sensors, which are respectively arranged on two specimen mounting seats. The pressure sensors are located at places where pressure fluctuations are obvious, which is more conducive to subsequent monitoring and analysis. The temperature sensors are distributed to monitor the throat, the beginning of the convergent section, and the middle and rear part of the divergent section, respectively, and can monitor temperature fluctuations before, during and after cavitation occurs. The vibration sensor is located on the back of the specimen, and can monitor the impact vibration signal of the specimen when it is subjected to cavitation, which is convenient for subsequent analysis.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The low-temperature pipeline cavitation and erosion test bench provided by the present invention significantly improves the spatial adaptability and experimental controllability by adopting a rectangular cross-section venturi design. In conjunction with the test specimens and a variety of sensors arranged along the axial direction, a precise correlation between the material cavitation damage and multi-physical field signals is achieved. A multimodal monitoring system is integrated, including synchronous detection of pressure, temperature, and vibration sensors. The linkage triggering of the venturi made of transparent material and an external high-speed camera can accurately capture the transient process of cavitation collapse. After the test is completed, the specimen is removed from the specimen mounting seat, and the microscopic damage morphology of the specimen surface is observed under an electron microscope and compared with the collected impact signal to obtain the instantaneous cavitation rupture impact size when the specimen is damaged, thereby ensuring the reliability and repeatability of the experimental data.

[0017] Compared with the circular cross-section venturi tube, the rectangular cross-section venturi tube of the present invention has the following advantages:

[0018] The present invention can test specimens of various materials in parallel. By expanding the width of the rectangular venturi tube and arranging multiple specimen mounting seats in the same venturi tube, specimens of different materials can be installed side by side (such as metal / ceramic comparison experiments), thereby realizing parallel testing of multiple specimens.

[0019] The present invention secures the specimen using an inlay groove and a specimen mounting seat. A removable sealing plate attached to the venturi tube allows for rapid replacement of the specimen on the mounting seat. After a single cryogenic experiment, the specimen in the venturi tube can be replaced simply by removing the sealing plate without disrupting the system's vacuum / cryogenic state, significantly shortening the experimental period for comparing cavitation rates of different materials. Furthermore, after the experiment, the sealing plate can be removed to quickly remove the specimen for SEM observation, avoiding morphological changes in corrosion products caused by prolonged heating. This makes the device particularly suitable for studying the synergistic mechanism of cavitation and cryogenic effects.

[0020] Installation is more flexible; rectangular flanges are used for connection to pipelines, and only one-way alignment is required, making it easier to operate than circular flanges, which require circumferential alignment. The rectangular cross-section allows for installation against walls or platform edges (especially suitable for low-temperature chambers with limited space), avoiding the waste of surrounding space caused by circular cross-sections. For example, they can be stacked in multi-layer experimental platforms or directly connected to other rectangular cross-section pipelines using their right-angle features.

[0021] It has excellent bending and torsional resistance. The asymmetric impact load generated by the collapse of cavitation bubbles in the Venturi tube will induce pipe distortion. The rectangular cross-section has a larger moment of inertia and a reasonable distribution of structural strength, which has better structural and mechanical properties. It can reduce flow fluctuations caused by structural deformation during the experiment and ensure the stability of the cavitation number. In low-temperature media such as liquid nitrogen, material shrinkage may destroy the sealing. The rigid structure of the rectangular tube can better maintain the flatness of the flange surface and prevent low-temperature leakage.

[0022] The specimen mounting seat of the present invention can be designed in a standardized manner so that only the specimen on the specimen mounting seat is replaced during the experiment instead of the entire venturi, thereby reducing the cost of using precious materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a front view of the structural diagram of the present invention.

[0024] Figure 2 Schematic diagram of the three-dimensional structure of the venturi tube of the present invention

[0025] Figure 3 Schematic diagram of the internal structure of the venturi tube of the present invention.

[0026] Figure 4 It is a schematic diagram of the sealing plate and venturi structure of the present invention.

[0027] Figure 5 It is a schematic diagram of the specimen mounting seat, specimen mounting groove and specimen structure of the present invention.

[0028] Among them, 1. liquid supply tank, 2. venturi tube, 21. inlay groove, 22. sensor mounting groove, 23. specimen mounting seat, 24. specimen mounting groove, 25. sealing plate, 251. bump, 252. card slot, 3. receiving tank, 4. specimen, 5. temperature sensor, 6. pressure sensor, 7. vibration sensor. DETAILED DESCRIPTION

[0029] The following combination Figures 1 to 5 , a detailed description of the specific embodiments of the present invention is provided. In the description of the present invention, it should be understood that the terms "center," "upper," "lower," "front," "back," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are intended only to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific direction, be constructed, or operate in a specific direction. Therefore, they should not be construed as limiting the present invention.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, features specified as "first" or "second" may explicitly or implicitly include one or more of such features; and in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0031] It should be noted that the circuit connections involved in the present invention all adopt conventional circuit connection methods and do not involve any innovation.

[0032] Example

[0033] like Figure 1 As shown, the low-temperature pipeline cavitation erosion test bench includes: a liquid supply tank 1, a venturi assembly and a receiving tank 3. The liquid supply tank 1 is used to store low-temperature liquid and is supplied by a quick cooling device, which is more convenient. A mass flow meter is installed in the liquid supply tank 1 to accurately measure the flow rate of the liquid and ensure the stability of the experimental conditions. In addition, the liquid supply tank 1 is also equipped with an electric regulating valve to adjust the supply pressure and flow of the liquid to meet the needs of different experimental conditions. Figure 2 、 Figure 3 and Figure 4 As shown, the venturi tube assembly includes: a venturi tube 2, a specimen mounting seat 23 and a plurality of sensors, such as Figure 1As shown, one end of the venturi tube 2 is connected to the liquid supply tank 1 to generate cavitation. Its internal structure and size can be designed and adjusted according to experimental requirements, such as Figure 2 and Figure 3 As shown, the cross-section of the flow channel of the venturi tube 2 is rectangular, and an inlay groove 21 and multiple sensor mounting grooves 22 are provided on the flow channel wall of the venturi tube 2. The inlay groove 21 is provided in the divergent section of the flow channel of the venturi tube 2; a specimen mounting seat 23 is embedded in the inlay groove 21, and a specimen mounting groove 24 is provided on the specimen mounting seat 23 for fixing the specimen 4; the materials used for the specimen 4 include X52 pipeline steel, 304 stainless steel, 5A05 aluminum alloy, PE63, and PE100, and are replaceable. The low-temperature pipeline cavitation and erosion test bench also includes an insulation component, specifically: an insulation shell and an insulation device. The insulation shell has a cavity and is sleeved on the outside of the venturi tube 2. A sealing setting is adopted at the sleeve connection between the insulation shell and the venturi tube 2, and both ends of the insulation shell have connecting ports connected to the inner cavity. The temperature control device is connected through the connecting ports to form a circulation loop in the inner cavity of the insulation shell. A part of the insulation shell sleeved outside the venturi tube is provided with a transparent observation window, and a high-speed camera is arranged outside the transparent observation window. The transient process of cavitation collapse is accurately captured by the linkage triggering of the venturi tube made of transparent material, the transparent observation window and the high-speed camera. It is worth noting that the insulation shell, temperature control equipment and high-speed camera can use existing equipment, and the structure of the insulation shell, temperature control equipment and high-speed camera models will not be described in detail here; multiple sensors include: vibration sensor 7, temperature sensor 5 and pressure sensor 6, the vibration sensor 7 is set on the specimen mounting seat 23; temperature sensor 5 and pressure sensor 6 are respectively embedded in the corresponding sensor mounting groove 22; pressure sensor 6 and temperature sensor 5 are respectively used to monitor the pressure and temperature changes in the experimental pipeline section in real time, providing key parameters for studying the cavitation phenomenon. The vibration sensor 7 is used to detect the vibration signal generated by the specimen 4 during the cavitation process, and further analyze the impact of cavitation on the structure. The receiving tank 3 is used to collect the liquid after passing through the experimental pipeline section, and at the same time perform preliminary separation and treatment on the liquid for subsequent recycling or discharge. The design of the receiving tank 3 takes into account the recovery efficiency and safety of the liquid to ensure the smooth progress of the experimental process.

[0034] In some embodiments, two inlay grooves 21 are provided, which are sequentially arranged at the divergent section of the venturi tube 2 flow channel near the middle of the throat of the venturi tube 2; specifically, at 15 mm and 36 mm near the middle of the throat of the venturi tube 2; Figure 5As shown, the cross-section of the specimen mounting groove 24 is trapezoidal, and the specimen 4 is a slot of a trapezoidal block structure, which is fixedly inserted into the specimen mounting groove 24. Two specimen mounting seats 23 are provided because the positions where cavitation clouds fall off are different under different cavitation conditions, in order to monitor in more detail the vibration signals when the cavitation cloud falls off and causes damage to the material surface when the cavitation bubble collapses, and to more conveniently observe the surface damage of the specimen 4 under an electron microscope.

[0035] In some embodiments, one side of the specimen mounting seat 23 with the mounting groove is flush with the flow channel wall of the venturi tube 2, and the specimen 4 fixed in the mounting groove is flush with the flow channel wall of the venturi tube 2, ensuring a smooth and stable flow field.

[0036] In some embodiments, one end of the inlay groove 21 passes through the side wall of the venturi tube 2 , and a detachable sealing member is disposed at the penetration point to facilitate the disassembly and removal of the test piece 4 .

[0037] like Figure 3 As shown, the inlay groove 21 penetrates the side wall of the venturi tube 2 and has an external through-hole to form a groove so that the through-hole presents a step-like structure. The sealing member is a sealing plate 25, and a protrusion 251 is connected to the plate surface of the sealing plate 25. The peripheral side of the protrusion 251 is provided with a sealing ring and a groove sealing combination. The sealing plate 25 is detachably arranged on the groove.

[0038] In some embodiments, one end of the specimen mount 23 extends beyond one end of the inlay groove 21, and one end of the specimen 4 extends beyond the end surface of the specimen mount 23. A locking groove 252 is defined on the protrusion 251 of the sealing plate 25. The locking groove 252 matches the structure of the end surface of the specimen mount 23 and corresponds to the position of the specimen mount, and is used to clamp and secure the specimen mount 23. Screw holes are defined on the sidewalls of the sealing plate 25 and the venturi 2, and the sealing plate 25 and the venturi 2 are secured together by screws, such that the protrusion 251 seals the groove, and the locking groove 252 on the protrusion 251 secures the specimen mount 23.

[0039] In some embodiments, the sensor mounting groove 22 and the sensor are fixed by sealant to ensure the sealing of the flow channel of the venturi tube 2 .

[0040] In some embodiments, there are four pressure sensors 6, which are arranged in sequence at the middle position of the throat of the venturi tube 2, and at 15mm, 36mm, and 48mm from the middle position of the throat of the divergent section; there are three temperature sensors 5, which are arranged in sequence at 12.5mm from the middle of the throat of the convergent section of the venturi tube 2, the middle of the throat, and 60mm from the middle of the throat of the divergent section; there are two vibration sensors 7, which are respectively arranged on two specimen mounting seats 23. The positions of the pressure sensors 6 are all where the pressure fluctuations are obvious, which is more conducive to subsequent monitoring and analysis. The distribution positions of the temperature sensors 5 monitor the throat, the beginning of the convergent section, and the middle and rear part of the divergent section, respectively, and can monitor the temperature fluctuations before, during, and after cavitation occurs. The vibration sensor 7 is located on the back of the specimen 4, and can monitor the impact vibration signal of the specimen 4 when it is subjected to cavitation, which is convenient for subsequent analysis.

[0041] The above disclosures are only several preferred specific embodiments of the present invention. However, the embodiments of the present invention are not limited thereto. Any changes that can be conceived by those skilled in the art should fall within the scope of protection of the present invention.

Claims

1. Low temperature pipeline cavitation erosion test bench, characterized by: include: A liquid supply tank (1) for storing cryogenic liquid; A venturi tube assembly comprises: a venturi tube (2) made of a transparent material, one end of which is connected to a liquid supply tank (1) and is used to generate cavitation; the cross section of the flow channel of the venturi tube (2) is rectangular; an inlay groove (21) and a plurality of sensor mounting grooves (22) are provided on the flow channel wall of the venturi tube (2); the inlay groove (21) is provided in the divergent section of the flow channel of the venturi tube (2); a specimen mounting seat (23) is inlaid in the inlay groove (21); a specimen mounting groove (24) is provided on the specimen mounting seat (23) and is used to fix a specimen (4); a plurality of sensors, including: a vibration sensor (7) provided on the specimen mounting seat (23); a temperature sensor (5) and a pressure sensor (6), respectively inlaid in corresponding sensor mounting grooves (22); The receiving tank (3) is used to collect the liquid after passing through the experimental pipeline section and perform preliminary separation and treatment on the liquid.

2. The low-temperature pipeline cavitation and erosion test bench according to claim 1 is characterized in that: There are two inlay grooves (21), which are sequentially arranged at the middle position of the throat of the venturi tube (2) in the divergent section of the venturi tube (2) flow channel; the cross section of the test piece installation groove (24) is trapezoidal, and the test piece (4) is a slot of a trapezoidal block structure, which is fixedly inserted into the test piece installation groove (24).

3. The low-temperature pipeline cavitation and erosion test bench according to claim 1 is characterized in that: One side of the test piece mounting seat (23) with the mounting groove is flush with the flow channel wall of the venturi tube (2), and the test piece (4) fixed in the mounting groove is flush with the flow channel wall of the venturi tube (2).

4. The low-temperature pipeline cavitation and erosion test bench according to claim 1 is characterized in that: One end of the inlay groove (21) passes through the side wall of the venturi tube (2), and a detachable sealing member is arranged at the penetration point.

5. The low-temperature pipeline cavitation and erosion test bench according to claim 4 is characterized in that: The inlay groove (21) penetrates the side wall of the venturi tube (2) and has an external through-hole opening with a groove, so that the through-hole presents a step-shaped structure. The sealing member is a sealing plate (25), and a protrusion (251) is connected to the plate surface of the sealing plate (25). The protrusion (251) is sealed and combined with the groove. The sealing plate (25) is detachably arranged on the groove.

6. The low-temperature pipeline cavitation erosion test bench according to claim 5, characterized in that: One end of the specimen mounting seat (23) protrudes from one end of the inlay groove (21), and one end of the specimen (4) protrudes from the end surface of one end of the specimen mounting seat (23). A clamping groove (252) is provided on the protrusion (251) of the sealing plate (25). The clamping groove (252) matches the structure of the end surface of the specimen mounting seat (23) and corresponds to the position of the specimen mounting seat, and is used for clamping and fixing the specimen mounting seat (23).

7. The low-temperature pipeline cavitation and erosion test bench according to claim 1 is characterized in that: The sensor mounting groove (22) and the sensor are fixed by means of sealant.

8. The low-temperature pipeline cavitation and erosion test bench according to claim 1 is characterized in that: There are four pressure sensors (6), which are sequentially arranged at the middle position of the throat of the venturi tube (2) and the divergent section near the middle position of the throat; there are three temperature sensors (5), which are sequentially arranged in the convergent section, the middle of the throat and the divergent section of the venturi tube (2); and there are two vibration sensors (7), which are respectively arranged on two specimen mounting seats (23).

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