A gas-liquid cavity test device and a gas-liquid cavity test method

Abstract

The present invention relates to the field of two-phase flow testing technology, and specifically to a gas-liquid pore cavity test device and a gas-liquid pore cavity test method. The gas-liquid pore cavity test device includes: a pore cavity model, a circulating water tunnel, an air supply and exhaust component, and a monitoring component; a circulating water tunnel, which is provided with a test section with adjustable flow rate and pressure, and the pore cavity model is installed above the test section and is connected to the test section; an air supply and exhaust component is connected to the pore cavity model and can supply or exhaust air to the pore cavity model to adjust the air layer height in the pore cavity model; a monitoring component is used to monitor the vibration, noise and video data of the pore cavity model and / or the circulating water tunnel. The present application controls the air layer height, pressure and flow rate of the pore cavity model by setting a circulating water tunnel and an air supply and exhaust component with flow rate and pressure adjustment capabilities, and adopts a specific parameter adjustment method to control the air layer height, pressure and flow rate of the pore cavity model, thereby reducing the influence of the coupled changes of multiple operating parameters of the gas-liquid pore cavity test on the experimental results.

Description

Technical Field

[0001] The present invention relates to the technical field of two-phase flow testing, and in particular to a gas-liquid cavity testing device and a gas-liquid cavity testing method. Background Art

[0002] Open cavities (hereinafter referred to as cavities) are ubiquitous on ships and marine structures, including sea-accessible tanks and sea-accessible between-ship structures with openings. Recent engineering practice has shown that these cavities typically contain two-phase media: gas and liquid. However, conventional research on the flow and acoustic properties of cavities has only considered the case of a single-phase liquid medium. Studies on cavities containing two-phase media (hereinafter referred to as gas-liquid cavities) are rare.

[0003] In related techniques, a cavity model to be tested is installed in a circulating water tunnel test section. Vibration sensors, hydrophones, and other instruments are mounted on the cavity to monitor the acoustic properties of the cavity. The water tunnel is then opened and the vibration and noise data of the cavity are recorded at a given flow rate. The only operating parameter in the test is the flow rate, which is easily adjustable. The peak frequency of the vibration and noise is the shear oscillation frequency, which is easy to identify.

[0004] However, compared to the cavities that only contained a single-phase liquid medium in the past, the flow and acoustic characteristics of the gas-liquid cavities are more complex. On the one hand, the gas-liquid two-phase medium will form a free liquid surface in the cavity, and the movement of the free liquid surface will have a certain impact on the flow and noise in the cavity. On the other hand, the gas is highly compressible, which will cause a series of changes in the characteristic frequency of the cavity. The above factors will result in many operating parameters for the gas-liquid cavities test in the experiment, including at least three items: flow rate, gas layer height, and gas pressure. There is also a correlation between the three parameters, which makes it more difficult to adjust a single variable. At the same time, the frequency components in the gas-liquid cavities noise are more complex, and specific testing methods and data processing methods are required to identify and extract the characteristic frequencies in the gas-liquid cavities noise. In summary, traditional test equipment and testing methods are difficult to meet the flow and acoustic characteristics testing of gas-liquid cavities. Summary of the Invention

[0005] In related technologies, cavity testing can only monitor and adjust flow rate. When the test object is a gas-liquid two-phase cavity, the flow and acoustic characteristics of the gas-liquid cavity are more complex, resulting in multiple operating parameters for the gas-liquid cavity test, and there are correlations between multiple parameters, making the adjustment of a single variable more difficult. At the same time, the frequency components of the gas-liquid cavity noise are more complex, requiring specific testing methods and data processing methods to identify and extract the characteristic frequencies in the gas-liquid cavity noise. Therefore, traditional cavity test equipment and testing methods are difficult to fully test the flow and acoustic characteristics of gas-liquid cavities.

[0006] The present application includes two aspects, one of which is a test device for a gas-liquid cavity, which has the ability to control the gas layer height, pressure, and flow rate of the cavity model, and can meet the flow and acoustic characteristics testing requirements of the gas-liquid cavity.

[0007] The second is a gas-liquid cavity testing method using the test device of the first aspect.

[0008] It is understandable that the gas-liquid cavity test involves many operating parameters, and these parameters are coupled. Adjusting one parameter will also change the other parameters, and specific steps need to be followed for adjustment. Furthermore, the gas-liquid cavity has many noise frequency components, and specific steps need to be followed to identify and extract them one by one. The method of this application overcomes the problem of complex and difficult-to-identify peak frequency components of gas-liquid cavity vibration noise through specific testing methods and data processing methods, thereby achieving the identification and extraction of the peak frequency of gas-liquid cavity vibration noise.

[0009] The specific invention contents of the two aspects are as follows:

[0010] In the first aspect, the test device of the gas-liquid cavity includes: a cavity model, a circulating water tunnel, an air supply and exhaust component and a monitoring component; wherein,

[0011] A circulating water tunnel is provided with a test section with adjustable flow rate and pressure, and the cavity model is installed above the test section and is connected to the test section;

[0012] an air supply and exhaust component, which is in communication with the cavity model and can supply or extract air to the cavity model to adjust the height of the air layer in the cavity model;

[0013] A monitoring component is used to monitor the vibration, noise and video data of the cavity model and / or the circulating water tunnel.

[0014] In conjunction with the first aspect, in some embodiments, the monitoring component includes:

[0015] A test chamber, which is installed on the side wall of the circulating water tunnel test section;

[0016] At least four hydrophones, two of which are disposed on the upstream wall of the cavity model, and the other two are disposed in the test cavity;

[0017] A pressure pulsation sensor is provided on the top surface of the cavity model;

[0018] At least four vibration acceleration sensors are arranged on the upstream wall, downstream wall, top surface and rear wall of the cavity model.

[0019] In conjunction with the first aspect, in some embodiments, the cavity model includes:

[0020] A cavity, a bottom of which is detachably provided with an orifice plate, and the cavity is connected to the circulating water hole through the orifice plate;

[0021] An observation window is provided on the cavity, and a liquid level scale line is provided on the observation window.

[0022] In combination with the first aspect, in some embodiments, the pressure regulation upper limit B of the circulating water tunnel satisfies the formula:

[0023]

[0024] Where A is the preset upper limit of the flow velocity to be measured, ρ is the density of the liquid medium in the water tunnel, and P0 is the static pressure of the test section when the cavity model is full of water and the flow velocity of the circulating water tunnel is 0 m / s.

[0025] In a second aspect, the present application provides a gas-liquid cavity testing method using the above-mentioned test device, comprising:

[0026] The circulating water tunnel is injected with water under normal pressure until the pore cavity model reaches a full water state; wherein, when the pore cavity model cannot reach a full water state under normal pressure, the static pressure of the circulating water tunnel is increased until the pore cavity model reaches a full water state.

[0027] Using a monitoring component to monitor the static pressure of the test section of the circulating water tunnel when it is full of water, and using the static pressure as a reference pressure value;

[0028] Under given working conditions, the air layer height of the cavity model and the flow rate of the test section are adjusted respectively by the air supply and exhaust components and the circulating water tunnel, and the vibration, noise and video data of the cavity model and the circulating water tunnel under given working conditions are monitored by the monitoring component.

[0029] In conjunction with the second aspect, in some embodiments, the step of adjusting the air layer height of the cavity model and the flow rate of the test section by the air supply and exhaust assembly and the circulating water tunnel under given operating conditions, and monitoring the vibration, noise, and video data of the cavity model and the circulating water tunnel under given operating conditions by the monitoring assembly, includes:

[0030] Step S1, adjusting the flow rate of the circulating water tunnel to 0 m / s, and maintaining the static pressure of the test section at the reference pressure value when the cavity model reaches a full water state;

[0031] Step S2: using the air supply and exhaust assembly to supply air to the cavity model to adjust the air layer height in the cavity model to a preset test height;

[0032] Step S3: testing the cavity model using a hammering method, and obtaining structural frequency data using the monitoring component;

[0033] Step S4, repeating the above steps S1 to S3 at different preset test heights to obtain the structural frequency data of the cavity model at different air layer heights.

[0034] In conjunction with the second aspect, in some embodiments, the step of adjusting the air layer height of the cavity model and the flow rate of the test section by the air supply and exhaust assembly and the circulating water tunnel under given operating conditions, and monitoring the vibration, noise, and video data of the cavity model and the circulating water tunnel under given operating conditions by the monitoring assembly, includes:

[0035] Step S1, adjusting the flow rate of the circulating water tunnel to 0 m / s, and adjusting the static pressure of the circulating water tunnel to the reference pressure value when the cavity model reaches a full water state;

[0036] Step S2: using the air supply and exhaust assembly to supply air to the cavity model to adjust the air layer height in the cavity model to a preset test height;

[0037] Step S3: pressurizing the circulating water tunnel to raise the liquid level in the cavity model until the circulating water tunnel pressure reaches a preset threshold;

[0038] Step S4, depressurizing the circulating water tunnel until the static pressure of the test section drops back to the reference pressure value, and the height of the gas layer in the cavity model recovers to the preset test height and oscillates;

[0039] Step S5, repeating the above steps S1 to S4 at different preset test heights, and obtaining piston oscillation information of the liquid level in the cavity model at different preset test heights through the hydrophone of the monitoring component.

[0040] In conjunction with the second aspect, in some embodiments, after obtaining the piston oscillation information of the cavity model at different preset test heights through the monitoring component, the method further includes:

[0041] Convert each set of piston oscillation information obtained into frequency domain data;

[0042] Multiple sets of frequency domain data are plotted into frequency-gas layer height cloud graphs, and the data points in the frequency-gas layer height cloud graphs that are distributed in a curve with the gas layer height are used as the piston frequencies of the cavity model at different gas layer heights.

[0043] In conjunction with the second aspect, in some embodiments, the step of adjusting the air layer height of the cavity model and the flow rate of the test section by the air supply and exhaust assembly and the circulating water tunnel under given operating conditions, and monitoring the vibration, noise, and video data of the cavity model and the circulating water tunnel under given operating conditions by the monitoring assembly, includes:

[0044] Step S1, adjusting the flow rate of the circulating water tunnel to 0 m / s, and adjusting the static pressure of the test section to the test pressure value;

[0045] Step S2: using the air supply and exhaust assembly to supply air to the cavity model to adjust the air layer height in the cavity model to a preset test height;

[0046] Step S3, closing the air supply and exhaust assembly, and adjusting the flow rate of the circulating water tunnel to a preset flow rate value;

[0047] Step S4, repeating the above steps S1 to S3 at different preset test heights, and obtaining piston oscillation information of the air layer height of the cavity model at the preset test pressure and different test heights through the hydrophone of the monitoring component.

[0048] In conjunction with the second aspect, in some embodiments, after obtaining piston oscillation information of the air layer height of the cavity model at a preset test pressure and different test heights through the hydrophone of the monitoring assembly, the method further includes:

[0049] Convert each set of piston oscillation information obtained into frequency domain data;

[0050] Multiple sets of frequency domain data are plotted into frequency-gas layer height cloud graphs, and the data points in the frequency-gas layer height cloud graphs that show a curve distribution of local peak frequencies with gas layer heights are used as the piston frequencies of the cavity model (2) at different gas layer heights.

[0051] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0052] This application achieves control of the gas layer height, pressure, and flow rate of the cavity to be tested by providing a circulating water tunnel and air supply and exhaust components with flow rate and pressure regulation capabilities. Furthermore, specific parameter adjustment methods can be combined to control the gas layer height, pressure, and flow rate of the cavity model to reduce the impact of the rich flow phenomena and complex noise components of the gas-liquid cavity on the experimental results. Furthermore, the test method embodiments of this application include specific test steps and data processing methods to achieve the identification and extraction of the gas-liquid cavity piston frequency from the test data. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0054] Figure 1 This is an overall schematic diagram of the test device in the embodiment of this application;

[0055] Figure 2 This is a partial schematic diagram of the test device in the embodiment of the present application;

[0056] Figure 3 Schematic diagram of the AA perspective in the embodiment of the present application;

[0057] Figure 4 This is a schematic diagram of the BB perspective in the embodiment of the present application;

[0058] Figure 5 This is a schematic diagram of an observation window in an embodiment of the present application;

[0059] Figure 6 This is a schematic diagram of an air supply and exhaust assembly in an embodiment of the present application;

[0060] Figure 7 This is a spectrum data diagram of a single set of air layer heights in an embodiment of the present application;

[0061] Figure 8 Spectral data diagram of multiple groups of air layer heights in the embodiment of the present application;

[0062] Figure 9 This is a frequency-air layer height cloud map obtained by the pressurized excitation method in the embodiment of this application;

[0063] Figure 10 This is a frequency-air layer height cloud map obtained using the fluid excitation method in the embodiment of this application.

[0064] In the figure: 1. Circulating water tunnel; 11. Test section; 2. Cavity model; 21. Liquid level mark; 22. Cavity; 23. Orifice plate; 24. Observation window; 3. Air supply and exhaust assembly; 31. Main valve; 32. Three-way valve; 33. Inlet pipe; 34. Exhaust pipe; 4. Vibration and noise monitoring assembly; 41. Test chamber; 42. Hydrophone; 43. Pressure pulsation sensor; 44. Vibration acceleration sensor; 5. Video recorder. DETAILED DESCRIPTION

[0065] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0066] Regarding related technologies, compared with traditional single-phase cavity tests, the gas-liquid cavity flow phenomena and noise characteristics are more complex and sensitive to parameters such as gas content and gas pressure. The variable parameters and measurement parameters in the test are richer, resulting in the existing cavity testing equipment being unable to meet the circulating water tunnel test requirements for conducting gas-liquid cavity tests.

[0067] First, as Figure 1 and Figure 2 As shown, the present application provides a gas-liquid cavity test device, which includes: a cavity model 2, a circulating water tunnel 1 and an air supply and exhaust component 3; wherein,

[0068] A circulating water tunnel 1 is provided with a test section 11 with adjustable flow rate and pressure, and the test section 11 is installed below the test section 11 and is connected to the cavity model 2; an air supply and exhaust component 3 is connected to the cavity model 2 and can supply or extract air to the cavity model 2; a monitoring component is used to monitor the vibration, noise and video data of the cavity model 2 and / or the circulating water tunnel 1.

[0069] It should be noted that current experimental research on cavity flow and acoustic characteristics is generally conducted in circulating water tunnels. For single-phase cavities, the experimental method is relatively simple because the flow phenomena and noise components are relatively simple, and the main control parameter of the experiment is only the flow rate. The general experimental process is as follows:

[0070] Process 1: Install the cavity model 2 in the test section of the circulating water tunnel 1, and install vibration sensors, hydrophones, etc. on the cavity to monitor the acoustic characteristics of the cavity;

[0071] Process 2: Open the water tunnel and record the vibration and noise data of the cavity at a given flow rate;

[0072] Process 3: Obtain the flow field distribution characteristics in the cavity through means such as PIV (Particle Image Velocimetry) or LDV (Laser Doppler Velocimetry).

[0073] It can be seen from the above process that the single-phase cavity test has fewer measured parameters and variable parameters, and the test process is simple.

[0074] It is understandable that for the gas-liquid cavity, due to the presence of the gas medium, the main control parameters of the test, in addition to the flow rate, must also consider the influence of parameters such as gas content and gas pressure, which requires the test device to have good gas parameter adjustment capabilities. At the same time, the presence of the gas medium introduces a free liquid surface to the gas-liquid cavity, making the flow phenomenon and noise components in the cavity more complicated. The applicant found that when the cavity contains a gas-liquid two-phase medium, the characteristic frequency of the gas-liquid cavity becomes richer and is sensitive to multiple parameters such as gas layer height, gas pressure, and flow rate. Therefore, in the experiment, at least the gas layer height, gas pressure, flow rate and other parameters need to be adjusted. Since the three parameters of gas layer height, gas pressure and flow rate are coupled and correlated, adjusting one of them will cause the other two parameters to change at the same time. In order to meet the control requirements of a single variable in the experimental study, it is necessary to follow specific test methods and steps to adjust the above parameters. The comprehensive adjustment method of multiple parameters is a key factor affecting the test results. In the present application, a circulating water tunnel 1 with adjustable flow rate and pressure is provided, and the air supply and exhaust component 3 is used to comprehensively control the air layer height, gas pressure and flow rate of the cavity model 2.

[0075] Specifically, the flow rate and pressure regulation capabilities of the circulating water tunnel 1 need to be set according to the test conditions. In some specific implementations, when the upper limit of the flow rate to be studied is A m / s, the upper limit of the pressure (absolute pressure) regulation of the water tunnel should not be less than B Pa. The corresponding relationship between A and B is as follows:

[0076]

[0077] Where ρ is the density of the liquid medium in the water tunnel, unit is kg / m 3 , P0 is the static pressure of the test section 11 of the water tunnel when the cavity model 2 is in a full water state and the water tunnel flow velocity is 0 m / s.

[0078] In some optional embodiments, the monitoring component includes: a video recorder 5 and a vibration noise monitoring component 4; wherein,

[0079] A video recorder 5 is used to record the liquid surface movement of the cavity model 2 ; a vibration and noise monitoring component 4 is used to monitor the noise, pressure pulsation and vibration acceleration of the cavity model 2 .

[0080] Specifically, if Figure 4 As shown, the video recorder 5 includes: a high-speed camera and a lighting lamp.

[0081] It is worth noting that, since the cavity model 2 has a gas-liquid two-phase medium during the test, its cavity is divided into a gas layer and a liquid layer, and the movement of the liquid surface in the cavity can be better monitored in real time through the video recorder 5.

[0082] Some specific real-time methods, such as Figure 2 and Figure 4 As shown, the cavity model 2 includes: a cavity 22 and an observation window 24; wherein,

[0083] The cavity 22 has a detachable orifice plate 23 at its bottom, and the cavity 22 is connected to the circulating water tunnel 1 through the orifice plate 23; an observation window 24 is provided on the cavity 22, and a liquid level scale line 21 is provided on the observation window 24.

[0084] Optionally, the cavity 22 is made of a steel plate with a thickness of not less than 12 mm, which can ensure that it has sufficient rigidity and reduce the impact of structural vibration on flow noise measurement.

[0085] Further, if Figure 5 As shown, observation window 24 is made of transparent organic glass with a thickness of at least 20 mm and is installed on the front wall of the cavity parallel to the flow direction (hereinafter referred to as the front wall) for observing the gas-liquid flow within the cavity. To mark the position of the gas-liquid interface, a liquid level scale line 21 is marked on the surface of observation window 24.

[0086] In some optional embodiments, the orifice plate 23 can be installed on the connection surface between the cavity and the circulating water tunnel 1 (hereinafter referred to as the cavity bottom surface) by using countersunk bolts.

[0087] It is understandable that this connection method facilitates the replacement of the orifice plate 23 during the test, while ensuring that the surface of the orifice plate 23 is flat and has no obvious protrusions or depressions after installation, thereby reducing the impact of the local structure on the flow field and the sound field.

[0088] In some optional embodiments, such as Figure 6 As shown, the air supply and exhaust assembly 3 includes: a main valve 31, a three-way valve 32, an air intake pipe 33 and an exhaust pipe 34; wherein,

[0089] The main valve 31 can be a ball valve, which is installed on the top surface of the cavity 22 near the upstream of the circulating water hole 1 to control the inflow and outflow of gas in the cavity and prevent residual gas in the pipe from flowing back into the cavity.

[0090] The intake and exhaust lines are connected to the main valve 31 via a three-way valve 32. The intake line's components and connection sequence are: three-way valve 32 - intake check valve in intake line 33 - intake on / off valve - compressed air source, which can be a compressed air cylinder, compressor, or the like. The exhaust line's components and connection sequence are: three-way valve - exhaust check valve - exhaust on / off valve.

[0091] In some preferred embodiments, the vibration noise monitoring assembly 4 includes: a test chamber 41, at least four hydrophones 42, a pressure pulsation sensor 43 and at least four vibration acceleration sensors 44; wherein,

[0092] A test chamber 41 is installed on the side wall of the test section of the circulating water tunnel 1; at least four hydrophones 42, two of which are arranged on the upstream wall of the pore model 2 and two are arranged in the test chamber 41; a pressure pulsation sensor 43 is arranged on the top surface of the pore model 2; at least four vibration acceleration sensors 44 are arranged on the upstream wall, downstream wall, top surface and rear wall of the pore model 2.

[0093] Alternatively, as Figure 3 As shown, the test chamber 41 is a rectangular chamber, which is installed on the side wall of the test section of the circulating water tunnel 1. The test chamber 41 and the water tunnel connection surface are isolated by organic glass.

[0094] It is understandable that the use of organic glass isolation can ensure that the sound in the water tunnel can be transmitted into the test cavity 41 while preventing the flow in the circulating water tunnel 1 from affecting the test cavity 41 .

[0095] Specifically, it is recommended to place at least two hydrophones 42 on the upstream wall of cavity 22, positioned below the lowest gas layer altitude under study so that they are submerged in liquid under the studied operating conditions. It is also recommended to place at least two hydrophones within test cavity 41. The pressure pulsation sensor 43 is placed on the top surface of the cavity model 2, with at least two recommended. The vibration acceleration sensor 44 is placed on the non-observation window wall of the cavity model 2, with at least one each on the upstream wall, downstream wall, top wall, and rear wall.

[0096] Furthermore, the hydrophone 42, the pressure pulsation sensor 43, and the vibration acceleration sensor 44 are connected to a data acquisition device, and the collected data are transmitted to a computer for analysis and storage.

[0097] It is worth noting that the present invention has designed an air supply and exhaust system and test system that meets the requirements of gas-liquid cavity testing, and provides a parameter adjustment range for the circulating water tunnel that satisfies the requirements for conducting gas-liquid cavity testing. The air supply and exhaust assembly fully considers the need for regulating the gas layer within the cavity and prevents the impact of residual gas backflow in the intake and exhaust lines on the test.

[0098] In a second aspect, the present application provides a gas-liquid cavity testing method using the above-mentioned test device.

[0099] It should be noted that the flow and acoustic characteristics of the gas-liquid cavity are more complex. On the one hand, the gas-liquid two-phase medium will form a free liquid surface in the cavity, and the movement of the free liquid surface will have a certain impact on the flow and noise in the cavity. On the other hand, the gas is highly compressible, which will cause a series of changes in the characteristic frequency of the cavity. The above factors will cause the following two points in the experiment: First, the gas-liquid cavity test has many operating parameters, including at least three items: flow rate, gas layer height, and gas pressure. There is also a correlation between the three parameters, which makes the adjustment of a single variable more difficult. Second, the peak frequency components in the vibration noise are complex, and certain steps and methods need to be taken to identify and extract different types of frequencies for subsequent analysis and research.

[0100] The present invention provides a general testing method for gas-liquid cavities, comprising the following steps:

[0101] Step S1: Fill the circulating water tunnel 1 with water until the cavity model 2 is full of water, and record the static pressure value of the test section 11 of the circulating water tunnel 1 at this time as the reference pressure value.

[0102] In some optional embodiments, step S1 includes: injecting water into the circulating water tunnel 1 at normal pressure until the pore model 2 is filled with water; if the pore model 2 cannot be filled with water at normal pressure, increasing the static pressure of the circulating water tunnel 1 until the pore model 2 is filled with water. The static pressure value of the test section 11 of the circulating water tunnel 1 at this time is recorded as the reference pressure value.

[0103] The specific implementation includes: closing the air intake on-off valve, opening the main valve 31 and the exhaust on-off valve, and placing the air supply and exhaust assembly 3 in the exhaust state. Filling the circulating water tunnel 1 with water. If the top surface of the pore model 2 is higher than that of the circulating water tunnel 1, the water tunnel pressure needs to be increased to allow the pore model 2 to reach a full water state. After the pore model 2 is full of water, closing the main valve 31 and the exhaust on-off valve. Recording the static pressure P0 of the test section of the circulating water tunnel 1 at this time serves as the baseline pressure. The cavity water filling process is now complete.

[0104] Step S2: The air layer height of the cavity model 2 is adjusted to a preset test height through the air supply and exhaust assembly 3, and the static pressure of the test section 11 of the circulating water tunnel 1 is simultaneously maintained at a reference pressure value.

[0105] Specifically, the exhaust switch valve of the exhaust pipe 34 is closed, and the main valve 31, the intake switch valve of the intake pipe 33, and the air source are opened to put the supply and exhaust assembly 3 into the intake state. The intake speed is adjusted by adjusting the opening of the main valve 31.

[0106] In some specific embodiments, when the gas layer height to be studied is H, gas is injected into the cavity 22 of the pore model 2 to adjust the gas layer height to approximately H. Because gas injection increases the water tunnel pressure, the water tunnel pressure must be simultaneously adjusted to maintain the static pressure of the test section of the circulating water tunnel 1 at P0. When the gas layer height is adjusted to H and the static pressure of the test section is P0, the main valve 31, the air inlet switch valve, and the gas source are closed. The gas layer height adjustment is complete.

[0107] Step S3: adjusting the flow rate of the circulating water tunnel 1 to a preset test flow rate, and maintaining the static pressure of the test section 11 of the circulating water tunnel 1 at a reference pressure value.

[0108] Specifically, let the flow velocity to be studied be V. First, adjust the flow velocity in circulating water tunnel 1 to V. Because changes in flow velocity can cause changes in the dynamic pressure in the test section of circulating water tunnel 1, causing the static pressure to deviate from P0, this can cause variations in the cavity pressure and gas layer height, making the comparisons unreliable. Therefore, after the flow velocity stabilizes at V, the water tunnel pressure needs to be readjusted to restore the static pressure in test section 11 to P0.

[0109] Step S4: monitoring the vibration, noise and video data of the cavity model 2 and the circulating water tunnel 1 under preset test conditions through the monitoring component.

[0110] It is worth noting that the above steps S1 to S4 are a general testing method for gas-liquid two-phase cavities.

[0111] In summary, the gas-liquid pore cavity test involves numerous operating parameters, and these parameters are coupled. Adjusting one parameter affects the others, requiring specific adjustments. In the general test method section, this method addresses the sensitivity of the gas-liquid pore cavity flow and acoustic fields to parameters such as gas layer height and pressure, providing detailed adjustment methods. Maintaining static pressure in the test section is a key factor influencing test results, and this approach is implemented throughout the entire test process.

[0112] Furthermore, this application provides a variety of testing methods for specific working conditions, including:

[0113] Specific working condition 1: used to obtain background noise test, which includes:

[0114] Step a: Replace the orifice plate 23 with a non-porous organic glass plate to seal the bottom surface of the cavity 22.

[0115] Step b: remove the air source on the air inlet pipe 33 and replace it with a water source, and fill the cavity 22 with water through the air inlet pipe 33.

[0116] Step c: record the data of the vibration noise monitoring component 4 within the flow rate range Vmin-Vmax under study, and obtain the background noise of each sensor at different flow rates.

[0117] Specific working condition 2 is used to obtain structural frequency test, which includes:

[0118] Step a: inject water into the circulating water tunnel 1 until the cavity model 2 is full of water, and record the static pressure value P0 of the test section 11 of the circulating water tunnel 1 at this time as the reference pressure value.

[0119] Step b: adjusting the flow rate of the circulating water tunnel 1 to 0 m / s, and adjusting the static pressure of the test section 11 to a reference pressure value.

[0120] Step c: When the water tunnel flow velocity is 0 m / s, the air layer height of the cavity model 2 is adjusted to the preset test height H through the air supply and exhaust component 3, and the static pressure P0 of the test section 11 of the circulating water tunnel 1 is simultaneously maintained at the reference pressure value.

[0121] Step d: Use the hammering method to obtain the structural natural frequency of the cavity 22 under the conditions of air layer height H and static pressure P0.

[0122] Step e: repeat the above steps b to d at different preset test heights H to obtain the structural frequency data of the cavity model 2 at different air layer heights.

[0123] As you can understand, the hammering method is a common method and will not be discussed in detail here. In gas-liquid cavity testing, considering that the structural frequency varies with gas layer height, hammering tests are conducted separately at different gas layer heights. This is different from traditional single-phase cavity testing. The hammering data primarily comes from the vibration acceleration sensor 44.

[0124] Specific working condition 3: a pressurized excitation method for obtaining piston frequency, which includes:

[0125] Step 1: Fill the circulating water tunnel 1 with water until the cavity model 2 is full of water, and use the static pressure value of the test section 11 of the circulating water tunnel 1 at this time as the reference pressure value.

[0126] It will be appreciated that the specific water injection and adjustment methods are as described in the general test methods.

[0127] Step 2: Adjust the flow rate of the circulating water tunnel 1 to 0 m / s, and maintain the static pressure of the test section 11 at the reference pressure value.

[0128] Step 3: Adjust the air layer height of the cavity model 2 to a preset test height H1 through the air supply and exhaust component 3.

[0129] Specifically, when the water tunnel flow velocity is 0 m / s and the static pressure of the test section is a reference pressure value, the air layer height in the cavity 22 is adjusted to a preset test height H1.

[0130] Step 4: Pressurize the circulating water tunnel 1 to increase the height of the liquid level in the cavity model 2

[0131] Specifically, the main valve 31 is closed, and the standard pressure of the circulating water tunnel 1 is increased to a value A, which is not less than 10 kPa. At this time, the air layer in the cavity model 2 is in a compressed state.

[0132] Step 5: Release the pressure of the circulating water tunnel 1 to restore the pressure in the cavity model 2 to the reference pressure value. At this time, the liquid surface oscillates under the action of inertia.

[0133] Specifically, the circulating water tunnel 1 is depressurized quickly, and the gas layer in the cavity falls back to the test height H1 under the reference pressure value, and oscillates around the test height H1 under the action of inertia.

[0134] Step 6: Record the time domain data of the hydrophone 42 , which contains the piston oscillation information when the air layer height is the test height H1 .

[0135] Step 7: When the water tunnel velocity is 0 m / s and the static pressure of the test section is normal pressure, the air layer height in the cavity 22 is adjusted to the preset test heights H2, H3, ..., H n Repeat steps 2 to 5 at each air layer height to obtain a set of data.

[0136] Step 8: Process the time domain data to obtain the piston frequency at different gas layer heights.

[0137] A specific implementation method of step 8 of the present application includes: setting the gas layer height to H1~H n The time domain data is converted into frequency domain data. The spectrum data at a single air layer height is as follows: Figure 7 As shown, H1~H n The entire set of spectrum data is as follows Figure 8 shown.

[0138] It is worth noting that if Figure 7 and Figure 8 It can be seen that there are a large number of peaks in the spectrum obtained from the experiment, and it is difficult to distinguish which peak is the piston frequency.

[0139] A preferred implementation of step 8 of the present application includes: setting the gas layer height to H1~H n The time domain data is converted into frequency domain data, and then the pcolor command in Matlab (or other similar methods) is used to convert the H1 to H n The frequency domain data is plotted as Figure 9The frequency-atmosphere height cloud chart shown above shows local peak areas, identified by color and legend. Some local peak areas are represented by straight lines perpendicular to the frequency axis, while others are represented by curves showing decreasing frequency with altitude. The data points on these curves correspond to piston frequencies at different altitudes.

[0140] It is worth noting that the pressure excitation method has no flow interference, so the piston frequency is clear and easy to extract.

[0141] Specific working condition 4: Fluid excitation method for obtaining piston frequency, which includes:

[0142] Step 1: Fill the circulating water tunnel 1 with water until the cavity model 2 is full of water, and record the static pressure value of the test section 11 of the circulating water tunnel 1 at this time as the reference pressure value.

[0143] It is worth noting that the specific water injection and gas layer height adjustment methods refer to the specific steps of the above-mentioned general test method.

[0144] Step 2: Adjust the flow rate of the circulating water tunnel 1 to 0 m / s, and adjust the static pressure of the test section 11 to the test pressure value P state.

[0145] Step 3: Adjust the air layer height of the cavity model 2 to the preset test height H1 through the air supply and exhaust component 3, and simultaneously maintain the static pressure of the test section 11 of the circulating water tunnel 1 at the reference pressure value.

[0146] In some specific embodiments, when the water tunnel flow velocity is 0 m / s and the static pressure of the test section is a test pressure value P, the air layer height in the cavity 22 is adjusted to a preset test height H1.

[0147] Step 4: Adjust the fluid flow rate in the circulating water tunnel 1 to the recommended flow rate value.

[0148] In some specific embodiments, the main valve 31 is closed and the flow rate of the water tunnel is adjusted to Vm / s. The recommended value of V may be 0.5 to 1.5.

[0149] Step 5: Record the time domain data of the hydrophone 42, which contains the piston oscillation information when the air layer height is H1.

[0150] Step 6: Test at different preset heights H2, H3, ..., H n Steps 2 to 5 are repeated, and multiple sets of time domain data are recorded by the hydrophone 42 .

[0151] Specifically, when the water tunnel flow velocity is 0 m / s and the static pressure of the test section is normal pressure, the gas layer height in the cavity 22 is adjusted to H2, H3, ..., H nRepeat steps 2 to 5 to obtain each set of time domain data.

[0152] Step 7: Process the time domain data to obtain the piston frequency at different gas layer heights under the test pressure P.

[0153] Step 7a: Set the air layer height to H1~H n Convert the time domain data into frequency domain data.

[0154] Step 7b: Use the pcolor command in Matlab (or other similar methods) to convert the H1 to H n The frequency domain data is plotted as Figure 10 The cloud chart shown above shows local peak areas, which can be identified by color and legend. Some local peak areas are distributed as straight lines perpendicular to the frequency axis, while others are distributed as curves showing frequency decreasing with gas layer height. The data points on these curves correspond to piston frequencies at different gas layer heights.

[0155] It's worth noting that the advantage of the fluid excitation method is that it can obtain the piston frequency at any ambient pressure P. However, its disadvantage is that flow interference exists. When the shear frequency of the fluid coincides with the piston frequency, frequency lock occurs, making it difficult to extract the piston frequency near the coincidence point. When using the fluid excitation method, the experiment can be repeated at different excitation flow rates V. As the flow rate V changes, the shear frequency changes accordingly, causing the coincidence point between the piston frequency and the shear frequency to change. By extracting data at different flow rates V, the frequency lock problem associated with the fluid excitation method can be avoided.

[0156] In summary, in the test device part, the present invention designs an air supply and exhaust system and a test system that meet the requirements of the gas-liquid cavity test, and provides a circulating water tunnel parameter adjustment range that meets the requirements of the gas-liquid cavity test. The air supply and exhaust system fully considers the requirements of the gas layer adjustment in the cavity, and can avoid the influence of the residual gas backflow in the intake and exhaust pipes on the test. In the general test method part, this method provides a detailed working condition adjustment method based on the characteristics of the gas-liquid cavity being sensitive to parameters such as gas layer height, pressure, and flow rate. Among them, the method of maintaining the static pressure of the test section is a key factor affecting the test results, and this method runs through all aspects of the test. Furthermore, the noise frequency components of the gas-liquid cavity are many, and it is necessary to follow specific steps to identify and extract them one by one. In particular, there is no relevant report on the experimental extraction method of the piston frequency. In the special working condition test method, this application introduces the method of using the device of the present invention to carry out background noise testing, structural frequency testing, piston frequency testing, and using data to make cloud maps and extract characteristic frequencies using cloud maps, which provides a new idea for gas-liquid cavity testing.

[0157] In the description of this application, it should be noted that the terms "upper" and "lower" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0158] It should be noted that, in this application, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprising a ..." does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0159] The foregoing is merely a list of specific embodiments of the present application, intended to enable those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features of the present application.

Claims

1. A test device for gas-liquid cavity, characterized in that: include: Cavity model (2); A circulating water tunnel (1) is provided with a test section (11) with adjustable flow rate and pressure, and the cavity model (2) is installed above the test section (11) and communicated with the test section (11); an air supply and exhaust component (3) which is in communication with the cavity model (2) and can supply or extract air to the cavity model (2) to adjust the height of the air layer in the cavity model (2); A monitoring component is used to monitor the vibration, noise and video data of the cavity model (2) and / or the circulating water tunnel (1).

2. The test device according to claim 1, characterized in that The monitoring components include: A test chamber (41) is installed on the side wall of the test section (11) of the circulating water tunnel (1); At least four hydrophones (42), two of which are arranged on the upstream wall of the cavity model (2), and the other two of which are arranged in the test cavity (41); a pressure pulsation sensor (43) disposed on the top surface of the cavity model (2); At least four vibration acceleration sensors (44) are arranged on the upstream wall surface, downstream wall surface, top surface and rear wall surface of the cavity model (2).

3. The test device according to claim 1, characterized in that The cavity model (2) comprises: A cavity (22) having a detachable orifice plate (23) at its bottom, wherein the cavity (22) is connected to the circulating water hole (1) via the orifice plate (23); An observation window (24) is provided on the cavity (22), and a liquid level scale line (21) is provided on the observation window (24).

4. The test device according to claim 1, characterized in that: The upper limit B of the pressure regulation of the circulating water tunnel (1) satisfies the formula: Wherein, A is the preset upper limit of the flow velocity to be measured, ρ is the density of the liquid medium in the water tunnel, and P0 is the static pressure of the test section (11) when the cavity model (2) is in a full water state and the flow velocity of the circulating water tunnel (1) is 0 m / s.

5. A gas-liquid cavity testing method using the test device according to claim 1, characterized in that: include: The circulating water tunnel (1) is injected with water under normal pressure until the pore cavity model (2) reaches a full water state; wherein, when the pore cavity model (2) cannot reach a full water state under normal pressure, the static pressure of the circulating water tunnel (1) is increased until the pore cavity model (2) reaches a full water state; Using a monitoring component to monitor the static pressure of the test section (11) of the circulating water tunnel (1) when it is full of water, and using the static pressure as a reference pressure value; Under given working conditions, the air layer height of the cavity model (2) and the flow rate of the test section (11) are adjusted respectively by the air supply and exhaust component (3) and the circulating water tunnel (1), and the vibration, noise and video data of the cavity model (2) and the circulating water tunnel (1) under given working conditions are monitored by the monitoring component.

6. The gas-liquid cavity testing method according to claim 5, characterized in that: The method comprises: adjusting the air layer height of the cavity model (2) and the flow rate of the test section (11) respectively through the air supply and exhaust component (3) and the circulating water tunnel (1) under given working conditions, and monitoring the vibration, noise and video data of the cavity model (2) and the circulating water tunnel (1) under given working conditions through the monitoring component, including: Step S1, adjusting the flow rate of the circulating water tunnel (1) to 0 m / s, and maintaining the static pressure of the test section (11) at a reference pressure value when the cavity model (2) reaches a full water state; Step S2, using the air supply and exhaust assembly (3) to supply air to the cavity model (2) to adjust the height of the air layer in the cavity model (2) to a preset test height; Step S3, testing the cavity model (2) using a hammering method, and obtaining structural frequency data using the monitoring component; Step S4, repeating the above steps S1 to S3 at different preset test heights to obtain the structural frequency data of the cavity model (2) at different air layer heights.

7. The gas-liquid cavity testing method according to claim 5, characterized in that: The method comprises: adjusting the air layer height of the cavity model (2) and the flow rate of the test section (11) respectively through the air supply and exhaust component (3) and the circulating water tunnel (1) under given working conditions, and monitoring the vibration, noise and video data of the cavity model (2) and the circulating water tunnel (1) under given working conditions through the monitoring component, including: Step S1, adjusting the flow rate of the circulating water tunnel (1) to 0 m / s, and adjusting the static pressure of the circulating water tunnel (1) to a reference pressure value when the cavity model (2) reaches a full water state; Step S2, using the air supply and exhaust assembly (3) to supply air to the cavity model (2) to adjust the height of the air layer in the cavity model (2) to a preset test height; Step S3, pressurizing the circulating water tunnel (1) to increase the liquid level in the cavity of the pore model (2) until the pressure of the circulating water tunnel (1) reaches a preset threshold; Step S4, depressurizing the circulating water tunnel (1) until the static pressure of the test section (11) drops back to the reference pressure value, and the height of the air layer in the cavity model (2) recovers to the preset test height and oscillation occurs; Step S5, repeating the above steps S1 to S4 at different preset test heights, and obtaining piston oscillation information of the liquid level in the cavity model (2) at different preset test heights through the hydrophone (42) of the monitoring component.

8. The gas-liquid cavity testing method according to claim 7, wherein: After obtaining the piston oscillation information of the cavity model (2) at different preset test heights through the monitoring component, the method further includes: Convert each set of piston oscillation information obtained into frequency domain data; Multiple sets of frequency domain data are plotted into frequency-gas layer height cloud graphs, and the data points in the frequency-gas layer height cloud graphs that show a curve distribution of local peak frequencies with gas layer heights are used as the piston frequencies of the cavity model (2) at different gas layer heights.

9. The gas-liquid cavity testing method according to claim 5, wherein: The method comprises: adjusting the air layer height of the cavity model (2) and the flow rate of the test section (11) respectively through the air supply and exhaust component (3) and the circulating water tunnel (1) under given working conditions, and monitoring the vibration, noise and video data of the cavity model (2) and the circulating water tunnel (1) under given working conditions through the monitoring component, including: Step S1, adjusting the flow rate of the circulating water tunnel (1) to 0 m / s, and adjusting the static pressure of the test section (11) to the test pressure value; Step S2, using the air supply and exhaust assembly (3) to supply air to the cavity model (2) to adjust the height of the air layer in the cavity model (2) to a preset test height; Step S3, closing the air supply and exhaust assembly (3), and adjusting the flow rate of the circulating water tunnel (1) to a preset flow rate value; Step S4, repeating the above steps S1 to S3 at different preset test heights, and obtaining piston oscillation information of the air layer height of the cavity model (2) at the preset test pressure and different test heights through the hydrophone (42) of the monitoring component.

10. The gas-liquid cavity testing method according to claim 9, wherein: After obtaining piston oscillation information of the gas layer height of the cavity model (2) at a preset test pressure and different test heights through the hydrophone (42) of the monitoring component, the method further includes: Convert each set of piston oscillation information obtained into frequency domain data; Multiple sets of frequency domain data are plotted into frequency-gas layer height cloud graphs, and the data points in the frequency-gas layer height cloud graphs that show a curve distribution of local peak frequencies with gas layer heights are used as the piston frequencies of the cavity model (2) at different gas layer heights.

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