Gas-liquid hole cavity testing device and gas-liquid hole cavity testing method

Abstract

The invention relates to the technical field of two-phase flow testing, in particular to a gas-liquid hole cavity testing device and a gas-liquid hole cavity testing method. The testing device for the gas-liquid pore cavity comprises a pore cavity model, a circulating water tunnel, a gas supply and exhaust assembly and a monitoring assembly, the circulating water tunnel is internally provided with a test section with adjustable flow velocity and pressure, and the hole cavity model is arranged above the test section and is communicated with the test section; the air supply and exhaust assembly is communicated with the hole cavity model and can convey air to the hole cavity model or exhaust air from the hole cavity model so as to adjust the height of an air layer in the hole cavity model; and the monitoring assembly is used for monitoring vibration, noise and video data of the hole cavity model and / or the circulating water tunnel. According to the application, the circulating water tunnel with the flow velocity and pressure adjusting capability and the air supply and exhaust assembly are arranged, and the air layer height, pressure and flow velocity of the hole cavity model are controlled by adopting a specific parameter adjusting method, so that the influence of coupling change of multiple operating parameters of the gas-liquid hole cavity test on an experimental result is reduced.

Description

Technical Field

[0001] The 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 commonly found on ships and marine structures, such as sea-access tanks and sea-access structures with openings. Engineering practice in recent years has shown that cavities in engineering practice generally contain gas and liquid two-phase media. However, traditional research on the flow and acoustic characteristics of cavities only considers the case where the cavity is a single-phase liquid medium, and there are few reports on cavities containing gas and liquid two-phase media (hereinafter referred to as gas-liquid cavities).

[0003] In the related art, the cavity model to be tested is installed in the circulating water tunnel test section, and vibration sensors, hydrophones, etc. are installed on the cavity to monitor the acoustic characteristics of the cavity; the water tunnel is opened, and the vibration and noise data of the cavity are recorded at a given flow rate. The operating parameter of the test is only the flow rate, which is easy to adjust. The peak frequency in the vibration noise is only the shear oscillation frequency, which is easy to identify.

[0004] However, compared with the pores that only contain single-phase liquid media in the past, the flow and acoustic characteristics of gas-liquid pores 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 gas-liquid cavity test to have many operating parameters 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 pore noise are more complex, and specific test methods and data processing methods are required to identify and extract the characteristic frequencies in the gas-liquid pore noise. In summary, traditional test equipment and test methods are difficult to meet the flow and acoustic characteristics testing of gas-liquid pores. Summary of the invention

[0005] In the related technologies, the cavity test can only monitor and adjust the 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 more operating parameters for the gas-liquid cavity test, and there are correlations between multiple parameters, which makes it more difficult to adjust a single variable. At the same time, the frequency components in the gas-liquid cavity noise are more complex, and specific test methods and data processing methods are required to identify and extract the characteristic frequencies in the gas-liquid cavity noise. Therefore, traditional cavity test equipment and test methods are difficult to 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 function of controlling the gas layer height, pressure and flow rate of the cavity model, and can meet the flow and acoustic characteristics test 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 pore cavity test has many operating parameters and multiple parameters are coupled. If one of them is adjusted, the other parameters will also change, and specific steps need to be followed for adjustment. In addition, there are many noise frequency components in the gas-liquid pore cavity, and specific steps need to be followed to identify and extract them one by one. In the method of the present application, a specific testing method and data processing method are used to overcome the problem that the peak frequency components of the gas-liquid pore cavity vibration noise are complex and difficult to identify, and the peak frequency of the gas-liquid pore cavity vibration noise can be identified and extracted.

[0009] The specific contents of the invention in 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, a gas supply and exhaust component and a monitoring component; wherein,

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

[0012] an air supply and exhaust assembly, which is in communication with the cavity model and can supply or exhaust 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 combination with the first aspect, in some implementations, the monitoring component includes:

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

[0016] At least 4 hydrophones, 2 of which are disposed on the upstream wall of the cavity model, and the other 2 are disposed in the test cavity;

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

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

[0019] In combination with the first aspect, in some embodiments, the cavity model comprises:

[0020] A cavity, the bottom of which is detachably provided with a perforated plate, and the cavity is connected with the circulating water tunnel through the perforated plate;

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

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

[0023]

[0024] 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 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, which comprises:

[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 through 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 through the monitoring component.

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

[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 by a hammering method, and obtaining structural frequency data by 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 combination with the second aspect, in some embodiments, the step of adjusting the air layer height of the pore model and the flow rate of the test section by the air supply and exhaust assembly and the circulating water tunnel under given working conditions, and monitoring the vibration, noise and video data of the pore model and the circulating water tunnel under given working conditions by the monitoring assembly comprises:

[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 increase the liquid level in the cavity of the pore 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] A plurality of sets of frequency domain data are plotted into a frequency-gas layer height cloud diagram, and the data points in the frequency-gas layer height cloud diagram showing a curve distribution of the local peak frequency with the gas layer height are used as the piston frequency of the cavity model at different gas layer heights.

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

[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 combination with the second aspect, in some embodiments, after obtaining the piston oscillation information of the gas 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] The multiple sets of frequency domain data are plotted into a frequency-gas layer height cloud diagram, and the data points in the frequency-gas layer height cloud diagram showing a curve distribution of the local peak frequency with the gas layer height are used as the piston frequency of the cavity model (2) at different gas layer heights.

[0051] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0052] This application realizes the control of the gas layer height, pressure, and flow rate of the cavity to be tested by setting a circulating water tunnel and a gas supply and exhaust assembly with flow rate and pressure regulation capabilities, and then can combine a specific parameter adjustment method 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 embodiment of this application includes specific test steps and data processing methods, which realizes 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 drawings required for use in the description of the embodiments will be briefly introduced below. 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 creative work.

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

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

[0056] Figure 3 This is a schematic diagram of the AA viewing angle in an 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 group of air layer heights in an embodiment of the present application;

[0061] Figure 8 It is a spectrum data diagram of multiple groups of air layer heights in the embodiment of the present application;

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

[0063] Fig.10 This is a frequency-air layer height cloud map obtained by the fluid excitation method in the embodiment of the present 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 solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0066] Regarding the relevant technologies, compared with the traditional single-phase cavity test, the gas-liquid cavity flow phenomenon 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 testing 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, the test section 11 is installed below the test section 11 and is connected to the pore cavity model 2; an air supply and exhaust component 3 is connected to the pore cavity model 2 and can supply or exhaust air to the pore cavity model 2; a monitoring component is used to monitor the vibration, noise and video data of the pore cavity model 2 and / or the circulating water tunnel 1.

[0069] It should be noted that the current experimental research on cavity flow and acoustic characteristics is generally carried out on circulating water tunnels. For single-phase medium cavities, since the flow phenomenon and noise components are relatively simple, and the main control parameter of the test is only the flow rate, the test method is relatively simple. The general test 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 PIV (Particle Image Velocimetry) or LDV (Laser Doppler Velocimetry) and other means.

[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 complex. 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 assembly 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 capacity 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 lower 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: 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 implementations, 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 noise monitoring component 4 is used to monitor the noise, pressure pulsation and vibration acceleration of the cavity model 2 .

[0080] Specifically, 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 removable 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 arranged on the cavity 22, and a liquid level scale line 21 is arranged 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 influence of structural vibration on the flow noise measurement.

[0085] Furthermore, if Figure 5 As shown, the observation window 24 is made of organic glass with a thickness of not less than 20 mm and good transparency, and is installed on the front wall surface of the cavity parallel to the flow direction (hereinafter referred to as the front wall surface) for observing the flow of gas and liquid in the cavity. In order to mark the position of the gas-liquid interface, a liquid level scale line 21 is marked on the surface of the observation window 24.

[0086] In some optional implementations, 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 countersunk bolts.

[0087] It can be understood that this connection method facilitates the replacement of the orifice plate 23 during the test, and at the same time ensures 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 implementations, 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 pipeline 33 and an exhaust pipeline 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 tunnel 1 to control the inlet and outlet of the gas in the cavity and prevent the residual gas in the pipe from flowing back into the cavity.

[0090] The intake pipeline and the exhaust pipeline are connected to the main valve 31 through the three-way valve 32. The composition and connection sequence of the intake pipeline are: three-way valve 32-intake check valve of the intake pipeline 33-intake switch valve-compressed gas source, and the compressed gas source can be a compressed gas cylinder, a compressor, etc. The composition and connection sequence of the exhaust pipeline are: three-way valve-exhaust check valve-exhaust switch 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, which is installed on the side wall of the test section of the circulating water tunnel 1; at least 4 hydrophones 42, 2 of which are arranged on the upstream wall of the pore model 2, and 2 are arranged in the test chamber 41; a pressure pulsation sensor 43, which is arranged on the top surface of the pore model 2; at least 4 vibration acceleration sensors 44, which are arranged on the upstream wall, downstream wall, top surface and rear wall of the pore model 2.

[0093] Alternatively, if 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, and 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 arrange at least two hydrophones 42 on the upstream wall of the cavity 22, which are located lower than the lowest air layer height under study, so that they are all in the liquid under the studied working conditions; it is recommended to arrange at least two in the test cavity 41. The pressure pulsation sensor 43 is arranged on the top surface of the cavity of the pore model 2, and it is recommended to arrange at least two. The vibration acceleration sensor 44 is arranged on the non-observation window wall of the cavity of the pore model 2, and it is recommended to arrange at least one on the upstream wall, downstream wall, top surface, 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 instrument, and the collected data are transmitted to a computer for analysis and storage.

[0097] It is worth noting that 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 assembly fully considers the requirements of adjusting the gas layer in the cavity, and can avoid the influence of residual gas reflux in the air intake and exhaust pipeline 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, there are many operating parameters in the gas-liquid cavity test, 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. 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, inject water into the circulating water tunnel 1 until the pore model 2 reaches a full water state, 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 implementations, step S1 includes: injecting water into the circulating water tunnel 1 at normal pressure until the pore model 2 reaches a full water state; wherein, when the pore model 2 cannot reach a full water state at normal pressure, increasing the static pressure of the circulating water tunnel 1 until the pore model 2 reaches a full water state. 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 method includes: closing the air intake switch valve, opening the main valve 31 and the exhaust switch valve, and putting the air supply and exhaust assembly 3 in the exhaust state. Fill the circulating water tunnel 1 with water. If the top surface of the pore cavity model 2 is higher than the top surface of the circulating water tunnel 1, it is necessary to increase the water tunnel pressure so that the pore cavity model 2 can reach the full water state. After the pore cavity model 2 is in the full water state, close the main valve 31 and the exhaust switch valve. Record the static pressure P0 of the test section of the circulating water tunnel 1 at this time as the reference pressure. At this time, the cavity water filling process is completed.

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

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

[0106] In some specific embodiments, when the height of the gas layer to be studied is H, the gas layer height is adjusted to near H by injecting gas into the cavity 22 of the pore model 2. Since gas injection will cause the water tunnel pressure to increase, it is necessary to synchronously adjust the water tunnel pressure so that the static pressure of the test section of the circulating water tunnel 1 is maintained at P0. When the gas layer height is adjusted to H and the static pressure of the test section is P0, close the main valve 31, the air inlet switch valve, and the gas source. The gas layer height adjustment is completed.

[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 rate to be studied be V, and first adjust the flow rate of the circulating water tunnel 1 to V. Since the change in flow rate will cause the dynamic pressure of the test section of the circulating water tunnel 1 to change, and the static pressure will deviate from P0, this will cause the pressure in the cavity and the height of the air layer to change, and lose comparability. Therefore, after the flow rate stabilizes at the flow rate V, it is necessary to readjust the water tunnel pressure so that the static pressure of the test section 11 returns to P0.

[0109] Step S4: monitor 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 general testing methods for gas-liquid two-phase cavities.

[0111] In summary, the gas-liquid pore cavity test has many operating parameters and multiple parameters are coupled. If one of them is adjusted, the other parameters will also change, and specific steps need to be followed for adjustment. In the general test method section, this method gives a detailed working condition adjustment method based on the characteristics that the gas-liquid pore cavity flow field and acoustic field are sensitive to parameters such as gas layer height and pressure. 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.

[0112] Furthermore, the present 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 made of 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 pipeline 33 and replace it with a water source, and fill the cavity 22 with water through the air inlet pipeline 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 pore model 2 reaches a full water state, 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 rate is 0 m / s, the air layer height of the cavity model 2 is adjusted to a preset test height H through the air supply and exhaust assembly 3, and the static pressure P0 of the test section 11 of the circulating water tunnel 1 is simultaneously maintained at a reference pressure value.

[0121] Step d: using a 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] It is understandable that the hammer method is a commonly used method and will not be described here. In the gas-liquid cavity test, considering that the structural frequency changes with the gas layer height, it is necessary to conduct hammer tests at different gas layer heights, which is different from the traditional single-phase cavity test. The hammer data mainly 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: inject water into the circulating water tunnel 1 until the pore model 2 is full of water, and take 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 as 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 assembly 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 to increase the standard pressure of the circulating water tunnel 1 to a value A, which is not less than 10 kPa. At this time, the air layer in the cavity of the pore 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 near the test height H1 due to 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 flow 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 whole 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 H1~H1 obtained in step 1 is converted into frequency domain data using the pcolor command in Matlab (or other similar methods). n The frequency domain data is plotted as Fig. 9The frequency-air layer height cloud diagram shown in the figure can identify the local peak area according to the color and legend in the cloud diagram. Among them, the distribution of a part of the local peak area is a straight line perpendicular to the frequency coordinate axis, and the distribution of another part of the peak area is a curve in which the frequency decreases with the air layer height. The data points on the local peak area distributed in the curve correspond to the piston frequency at different air layer heights.

[0140] It is worth noting that, due to the absence of flow interference in the pressurized excitation method, 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: inject water into the circulating water tunnel 1 until the pore 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 a preset test height H1 through the air supply and exhaust assembly 3, and simultaneously maintain the static pressure of the test section 11 of the circulating water tunnel 1 at a 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 the 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, and the recommended value of V can be 0.5-1.5.

[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 repeatedly performed, and multiple groups 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 to frequency domain data.

[0154] Step 7b: Use the pcolor command in Matlab (or other similar methods) to convert H1 to H n The frequency domain data is plotted as Fig.10 The cloud map shown in the figure can identify the local peak area according to the color and legend in the cloud map. Among them, the distribution of a part of the local peak area is a straight line perpendicular to the frequency coordinate axis, and the distribution of another part of the peak area is a curve in which the frequency decreases with the gas layer height. The data points on the local peak area distributed in the curve correspond to the piston frequency at different gas layer heights.

[0155] It is worth mentioning that the advantage of the fluid excitation method is that the piston frequency under any ambient pressure P can be obtained. The disadvantage is that there is flow interference. When the shear frequency of the fluid coincides with the piston frequency, frequency locking will occur, making it difficult to extract the piston frequency near the coincidence point. When using the fluid excitation method, the test can be repeated at different excitation flow rates V. When the flow rate V changes, the shear frequency changes accordingly, thereby changing the coincidence point between the piston frequency and the shear frequency. By extracting data at different flow rates V, the frequency locking problem caused by 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 reflux in the intake and exhaust pipeline on the test. In the general test method part, this method provides a detailed working condition adjustment method in view of 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, especially the experimental extraction method of the piston frequency, which has not been reported. 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 new ideas for gas-liquid cavity testing.

[0157] In the description of the present application, it should be noted that the terms "upper", "lower", etc. 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 the present application and simplifying the description, rather than indicating or implying 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 the present 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 it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present 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 only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such 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 including 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, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0159] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

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 is connected to the test section (11); an air supply and exhaust component (3), which is in communication with the pore cavity model (2) and can supply or extract air to the pore cavity model (2) so as to adjust the height of the air layer in the pore 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) installed on the side wall surface of the test section (11) of the circulating water tunnel (1); At least four hydrophones (42), wherein two of the hydrophones (42) are arranged on the upstream wall of the cavity model (2), and the other two of the hydrophones (42) 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) 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).

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: In the formula, A is the preset upper limit value 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 as claimed in 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) so as 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) by a hammering method, and obtaining structural frequency data by 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 pore 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) so as 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 a preset test height and oscillates; 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, characterized in that: 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 data points in the frequency-gas layer height cloud graphs showing a curve distribution of local peak frequencies with gas layer heights are used as piston frequencies of the cavity model (2) at different gas layer heights.

9. 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 test section (11) to a test pressure value; Step S2, using the air supply and exhaust assembly (3) to supply air to the cavity model (2) so as 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, characterized in that: 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 comprises: 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 data points in the frequency-gas layer height cloud graphs showing a curve distribution of local peak frequencies with gas layer heights are used as piston frequencies of the cavity model (2) at different gas layer heights.

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