A water tunnel test device and test method

Abstract

The present invention belongs to the technical field of fluid test, and relates to a water tunnel test device and a test method. The device includes two water tanks and a water tunnel test section; air bags are arranged in the inner cavities of the two water tanks, and the two air bags are respectively connected to an external compressed air source through air pipes. A water cavity is formed between the air bag and the inner wall of the water tank where it is located, and the water cavity is filled with water; the water inlet of the water tunnel test section is respectively connected to the water cavities of the two water tanks through a water inlet three-way valve, and the water outlet is respectively connected to the water cavities of the two water tanks through a water outlet three-way valve. The present invention can, through the inflation and deflation operations of the two air bags and the regulation of the working states of the water inlet three-way valve and the water outlet three-way valve, make the water circulate between the two water tanks and continuously flow through the water tunnel test section, thereby realizing the closed-loop operation of the water tunnel test in a way of air pressure loading, and solving the problems of complex conversion of water flow direction, poor test stability, and difficult precise control of pressure change in the existing closed-loop water tunnel system due to directly pressurizing by a pump.

Description

Technical Field

[0001] The present invention belongs to the technical field of fluid testing, and particularly relates to a water tunnel test device and a test method. Background Art

[0002] In water tunnel tests, closed-loop water tunnel systems are widely used because they can reuse the test medium (water), reducing water resource consumption and test costs.

[0003] However, most existing closed-loop water tunnel systems use a direct pump pressurization method. This method often requires complex mechanical structures when changing the water flow direction, not only increasing the design complexity and manufacturing cost, but also potentially affecting the test stability and continuity due to frequent pump start-stop. In addition, there are certain limitations in pressure control when directly using a pump for pressurization, making it difficult to achieve smooth and precise pressure changes, which is particularly disadvantageous in water tunnel tests that require high-precision simulation of water flow conditions. Summary of the Invention

[0004] Aiming at the deficiencies in the related art, the present invention provides a water tunnel test device and a test method, aiming to solve the problems of complex water flow direction conversion, poor test stability, and difficult precise control of pressure changes in existing closed-loop water tunnel systems due to direct pump pressurization.

[0005] The present invention provides a water tunnel test device, including:

[0006] A first water tank and a second water tank, each of which has an airbag in its inner cavity; the two airbags are respectively connected to an external compressed air source through a ventilation pipe, and a water cavity is formed between each airbag and the inner wall of the water tank where it is located, and each water cavity is filled with water;

[0007] A water tunnel test section, whose water inlet is respectively connected to the water cavities of the first water tank and the second water tank through an inlet three-way valve, and whose water outlet is respectively connected to the water cavities of the first water tank and the second water tank through an outlet three-way valve;

[0008] The water tunnel test device is configured to inflate the airbag in the first water tank and deflate the airbag in the second water tank, adjust the working states of the inlet three-way valve and the outlet three-way valve, so that the water in the first water tank flows through the water tunnel test section under the inflation pressure and then enters the second water tank until the water volume in the second water tank reaches a preset value; then switch the working states of the inlet three-way valve and the outlet three-way valve, inflate the airbag in the second water tank and deflate the airbag in the first water tank, so that the water in the second water tank flows through the water tunnel test section under the inflation pressure and then enters the first water tank until the water volume in the first water tank reaches a preset value; switch the working states of the inlet three-way valve and the outlet three-way valve again and repeat the above process to make the water continuously flow through the water tunnel test section.

[0009] In some of these embodiments, the water tunnel test device further includes a water storage tank and a water supply pump; the water storage tank is respectively connected to the water cavities of the first water chamber and the second water chamber through a water injection pipe; the water supply pump is installed on the water injection pipe to pump the water in the water storage tank into the water cavities of the first water chamber and the second water chamber.

[0010] In some of these embodiments, the upper parts of the water cavities of the first water chamber and the second water chamber are respectively connected to the water storage tank through an overflow pipe; a switchable valve is provided on each overflow pipe.

[0011] In some of these embodiments, the airbag is a telescopic airbag, the upper end of the airbag is connected to the top of the cavity of the water chamber where it is located, the air pipe penetrates through the top wall of the water chamber where the airbag is located and is connected to the airbag, and the lower end of the airbag can move up and down reciprocally under the action of internal air pressure and external water pressure.

[0012] In some of these embodiments, both the first water chamber and the second water chamber are cylindrical silos, the outer shape of the airbag is cylindrical and can be telescopic along the axis, and the airbag and the water chamber where it is located are coaxially arranged.

[0013] In some of these embodiments, the lower part of the water cavity of the first water chamber is connected to the inlet three-way valve through a first drain pipe and is connected to the outlet three-way valve through a first return pipe; the lower part of the water cavity of the second water chamber is connected to the inlet three-way valve through a second drain pipe and is connected to the outlet three-way valve through a second return pipe.

[0014] In some of these embodiments, the compressed air source is a gas storage tank filled with compressed air.

[0015] The present invention also provides a water tunnel test method, which is carried out by using the aforementioned water tunnel test device, and includes the following steps:

[0016] S1. Pre-inflate the two airbags respectively, and make the initial air pressure in the airbag of the first water chamber less than the initial air pressure in the airbag of the second water chamber;

[0017] S2. Start the water supply pump, pump the water in the water storage tank into the first water chamber and the second water chamber, and make the water fill the water cavity of the first water chamber, the water cavity of the second water chamber, the connecting pipeline between the first water chamber and the water tunnel test section, the connecting pipeline between the second water chamber and the water tunnel test section, and the water tunnel test section; then turn off the water supply pump;

[0018] S3. Inflate the airbag in the first water chamber and deflate the airbag in the second water chamber, adjust the working states of the inlet three-way valve and the outlet three-way valve, so that the water in the first water chamber flows through the water tunnel test section under the inflation pressure and then enters the second water chamber until the water volume in the second water chamber reaches a preset value; stop inflating the airbag in the first water chamber;

[0019] S4. Switch the working states of the water inlet three-way valve and the water outlet three-way valve, inflate the airbag in the second water sump, and deflate the airbag in the first water sump, so that the water in the second water sump flows through the water tunnel test section under the inflation pressure and then enters the first water sump until the water volume in the first water sump reaches the preset value; stop inflating the airbag in the second water sump;

[0020] S5. Repeat steps S3 and S4 to make the water continuously flow through the water tunnel test section.

[0021] In some embodiments, in steps S3 and S4, during the deflation process and at the end of deflation of the airbag in the first water sump or the second water sump, the air pressure in the airbag is always greater than zero.

[0022] Based on the above technical solutions, the water tunnel test device and test method in the embodiments of the present invention can solve the deficiencies of the existing closed-loop circulating water tunnel system using pump pressurization. Through the inflation and deflation of the airbag and the switching of the two three-way valves before and after the water tunnel test section, the closed-loop operation of the air pressure loading type water tunnel test is realized, improving the stability, continuity and reliability of the water tunnel test. Description of the Drawings

[0023] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0024] Figure 1 is a schematic structural diagram of the water tunnel test device of the present invention;

[0025] Figure 2 is a schematic diagram of the water flow direction during the water tunnel test using the water tunnel test device of the present invention.

[0026] In the figure: 10, the first water sump; 11, the first drain pipe; 12, the first return pipe; 20, the second water sump; 21, the second drain pipe; 22, the second return pipe; 30, the airbag; 31, the ventilation pipe; 40, the water tunnel test section; 41, the water inlet three-way valve; 42, the water outlet three-way valve; 51, the water storage tank; 52, the water supply pump; 53, the water injection pipe; 531, the main water injection pipe; 532, the branch water injection pipe; 54, the overflow pipe. Detailed Embodiments

[0027] Next, the technical solutions in the embodiments will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "lateral", "longitudinal", "upper", "lower", "top", "bottom", "inner", "outer", "left", "right", "front", "rear", "vertical", "horizontal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention 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 thus should not be construed as a limitation on the present invention.

[0029] The terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features.

[0030] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Referring Figure 1 、 Figure 2 As shown, the present invention provides a water tunnel test device, which includes a first water tank 10, a second water tank 20 and a water tunnel test section 40.

[0032] An airbag 30 is provided in the inner cavity of the first water tank 10 and the inner cavity of the second water tank 20. A water cavity is formed between each airbag 30 and the inner wall of the water tank where it is located, and each water cavity is filled with water; the two airbags 30 are respectively connected to an external compressed air source through an air pipe 31; further, each airbag 30 can be inflated or deflated through the compressed air source to change the volume of the inner cavity of the airbag 30, thereby regulating the water pressure in each water tank.

[0033] The water tunnel test section 40 is used for conducting tests such as fluid mechanics. The front and rear ends of the water tunnel test section 40 are provided with a water inlet and a water outlet. The water inlet of the water tunnel test section 40 is respectively communicated with the water chambers of the first water tank 10 and the second water tank 20 through a water inlet three-way valve 41; specifically, the water inlet three-way valve 41 has two inlets and one outlet. The water chamber of the first water tank 10 is connected to one inlet of the water inlet three-way valve 41 through a first drain pipe 11, the water chamber of the second water tank 20 is connected to the other inlet of the water inlet three-way valve 41 through a second drain pipe 21, and the water inlet of the water tunnel test section 40 is connected to the outlet of the water inlet three-way valve 41. The water outlet of the water tunnel test section 40 is respectively communicated with the water chambers of the first water tank 10 and the second water tank 20 through a water outlet three-way valve 42; specifically, the water outlet three-way valve 42 has one inlet and two outlets. The water outlet of the water tunnel test section 40 is connected to the inlet of the water outlet three-way valve 42, the water chamber of the first water tank 10 is connected to one outlet of the water outlet three-way valve 42 through a first return pipe 12, and the water chamber of the second water tank 20 is connected to the other outlet of the water outlet three-way valve 42 through a second return pipe 22. Thus, the water tunnel test section 40 is located between the first water tank 10 and the second water tank 20, and the two water tanks are connected to each other through the water tunnel test section 40. Further, by adjusting the working state of the water inlet three-way valve 41, that is, switching the two inlets of the water inlet three-way valve 41, the incoming path of the water entering the water tunnel test section 40 can be adjusted; by adjusting the working state of the water outlet three-way valve 42, that is, switching the two outlets of the water outlet three-way valve 42, the outgoing path of the water flowing out of the water tunnel test section 40 can be adjusted.

[0034] Further explanation: The water tunnel test device is configured to inflate the airbag 30 in the first water tank 10 to increase the water pressure in the first water tank 10, deflate the airbag 30 in the second water tank 20, and adjust the working states of the water inlet three-way valve 41 and the water outlet three-way valve 42 (that is, the inlet of the water inlet three-way valve 41 facing the first water tank 10 is opened and the inlet facing the second water tank 20 is closed, and the outlet of the water outlet three-way valve 42 facing the first water tank 10 is closed and the outlet facing the second water tank 20 is opened), so that the water in the first water tank 10 is discharged from the first water tank 10 under the inflation pressure, and the water flows through the first drain pipe 11, the water inlet three-way valve 41, the water tunnel test section 40, the water outlet three-way valve 42 and the second return pipe 22 in sequence and then enters the second water tank 20. Refer to Figure 2The flow direction indicated by the dotted arrow in the figure (i.e., the water in the first water storage tank 10 flows into the second water storage tank 20) until the water volume in the second water storage tank 20 reaches a preset value; then switch the working states of the water inlet three-way valve 41 and the water outlet three-way valve 42 (i.e., the water inlet three-way valve 41 closes the inlet towards the first water storage tank 10 and opens the inlet towards the second water storage tank 20, and the water outlet three-way valve 42 opens the outlet towards the first water storage tank 10 and closes the outlet towards the second water storage tank 20), inflate the airbag 30 in the second water storage tank 20 to increase the water pressure in the second water storage tank 20, and deflate the airbag 30 in the first water storage tank 10, so that the water in the second water storage tank 20 is discharged from the second water storage tank 20 under the inflation pressure. The water flows through the second drain pipe 21, the water inlet three-way valve 41, the water tunnel test section 40, the water outlet three-way valve 42 and the first return pipe 12 in sequence and then enters the first water storage tank 10. Refer to Figure 2 The flow direction indicated by the dashed line arrow in the figure (i.e., the water in the second water storage tank 20 flows into the first water storage tank 10) until the water volume in the first water storage tank 10 reaches a preset value; switch the working states of the water inlet three-way valve 41 and the water outlet three-way valve 42 again and repeat the above process, so that the water can continuously flow through the water tunnel test section 40, which is convenient for fluid mechanics and other tests in the water tunnel test section 40.

[0035] In the above-mentioned schematic embodiment, through the setting of two water storage tanks and the airbags 30 inside them, and the setting of two three-way valves before and after the water tunnel test section 40, the construction of a pneumatically driven closed-loop water tunnel system is realized. It can control the water pressure in a pneumatic loading manner to achieve the stable discharge and inflow of water in the water storage tank, and can realize the cyclic flow of water between the two water storage tanks and the quick switching of the water flow direction, thereby realizing the closed-loop operation of the water tunnel test; compared with the existing closed-loop water tunnel system that directly pressurizes with a pump, the pneumatic loading type water tunnel test device of this embodiment has a simple structure, is easy to maintain, has a low cost, and has strong practicability. It can control the water flow pressure more precisely and smoothly, switch the water flow direction more accurately and quickly, improve the stability and continuity of the water tunnel test, and is especially suitable for water tunnel tests with high simulation accuracy of water flow conditions.

[0036] Refer to Figure 1 、 Figure 2As shown, in some embodiments, the water tunnel test device further includes a water storage tank 51 and a water supply pump 52. The water storage tank 51 is connected to the water cavities of the first water chamber 10 and the second water chamber 20 respectively through a water injection pipe 53; specifically, the water injection pipe 53 includes a main water injection pipe 531 and two water injection branch pipes 532. One end of the main water injection pipe 531 is connected to the water storage tank 51, and the other end is connected to one ends of the two water injection branch pipes 532. The other ends of the two water injection branch pipes 532 are respectively connected to the water cavities of the two water chambers. The water supply pump 52 is installed on the main water injection pipe 531 of the water injection pipe 53 for pumping the water in the water storage tank 51 into the water cavities of the first water chamber 10 and the second water chamber 20; specifically, when the water supply pump 52 is started, the water in the water storage tank 51 is pumped into the water cavities of the first water chamber 10 and the second water chamber 20, and the water cavities of the two water chambers, the connecting pipelines (i.e., the first drain pipe 11, the first return pipe 12, the second drain pipe 21 and the second return pipe 22) between the two water chambers and the water tunnel test section 40, and the water tunnel test section 40 are all filled with water; after the water supply pump 52 is closed, the water in the two water chambers will not flow back into the water storage tank 51. Further, in some embodiments, the upper parts of the water cavities of the first water chamber 10 and the second water chamber 20 are respectively connected to the water storage tank 51 through an overflow pipe 54, and each overflow pipe 54 is provided with a switchable valve (not shown); referring to Figure 2 As shown by the solid arrow in the figure, when starting the water supply pump 52 to pump water into the two water chambers, open the valve on the overflow pipe 54. When there is continuous water flowing back into the water storage tank 51 in the overflow pipe 54, it indicates that the water injection operation of the water tunnel test device is completed, and then close the valve on the overflow pipe 54 and the water supply pump 52; thereby ensuring that the amount of water in the water tunnel test device is sufficient and constant during the test process.

[0037] Referring to Figure 1 As shown, in some embodiments, the airbag 30 is a foldable telescopic airbag 30, and the upper end of the airbag 30 is connected to the top of the cavity of the water chamber where it is located; one end of the ventilation pipe 31 penetrates through the top wall of the water chamber where the airbag 30 is located and is connected to the airbag 30, and the other end of the ventilation pipe 31 is located outside the water chamber and is connected to an external compressed air source (not shown); when performing inflation and deflation operations on the airbag 30 through the compressed air source, the volume of the airbag 30 will change accordingly, and the lower end of the airbag 30 can move up and down reciprocally under the combined action of the internal air pressure and the external water pressure; thus, by regulating the inflation and deflation speed and air pressure of the airbag 30, the water flow pressure and flow rate can be accurately and smoothly controlled.

[0038] Referring to Figure 1 As shown, in some embodiments, both the first water chamber 10 and the second water chamber 20 are cylindrical silos, the outer shape of the airbag 30 is cylindrical and can be axially telescopic, the airbag 30 and the water chamber where it is located are coaxially arranged, and the ventilation pipe 31 and the airbag 30 are also coaxially arranged; thus making the structure of the water tunnel test device compact and regular.

[0039] Referring toFigure 1 As shown, in some embodiments, the first drain pipe 11 and the first return pipe 12 are both connected to the lower part of the water cavity of the first water tank 10, and the second drain pipe 21 and the second return pipe 22 are both connected to the lower part of the water cavity of the second water tank 20, that is, the drain pipe and the return pipe are both located at the bottom end in the elongation direction of the airbag 30. Thus, it is beneficial to the smooth discharge and inflow of water in the water tank.

[0040] In some embodiments, the compressed air source is an air storage tank filled with compressed air, which provides a reliable air pressure driving source for the water tunnel test device.

[0041] Reference Figure 1 、 Figure 2 As shown, the present invention also provides a water tunnel test method, which is carried out by using the aforementioned water tunnel test device. The water tunnel test method includes the following steps:

[0042] S1. Pre-inflate the airbags 30 of the first water tank 10 and the second water tank 20 respectively through the compressed air source, and make the initial air pressure in the airbag 30 of the first water tank 10 less than the initial air pressure in the airbag 30 of the second water tank 20;

[0043] S2. Open the valve on the overflow pipe 54, start the water supply pump 52, pump the water in the water storage tank 51 into the first water tank 10 and the second water tank 20, and make the water fill the water cavity of the first water tank 10, the water cavity of the second water tank 20, the connecting pipeline between the first water tank 10 and the water tunnel test section 40, the connecting pipeline between the second water tank 20 and the water tunnel test section 40, and the water tunnel test section 40; close the valve on the overflow pipe 54 and the water supply pump 52;

[0044] S3. Inflate the airbag 30 of the first water tank 10 and deflate the airbag 30 of the second water tank 20, adjust the working states of the inlet three-way valve 41 and the outlet three-way valve 42, so that the water in the first water tank 10 flows through the first drain pipe 11, the inlet three-way valve 41, the water tunnel test section 40, the outlet three-way valve 42 and the second return pipe 22 in sequence under the inflation pressure and then enters the second water tank 20 until the water volume in the second water tank 20 reaches the preset value; stop inflating the airbag 30 of the first water tank 10 and stop deflating the airbag 30 of the second water tank 20;

[0045] S4. Switch the working states of the inlet three-way valve 41 and the outlet three-way valve 42, inflate the airbag 30 of the second water tank 20 and deflate the airbag 30 of the first water tank 10, so that the water in the second water tank 20 flows through the second drain pipe 21, the inlet three-way valve 41, the water tunnel test section 40, the outlet three-way valve 42 and the first return pipe 12 in sequence under the inflation pressure and then enters the first water tank 10 until the water volume in the first water tank 10 reaches the preset value; stop inflating the airbag 30 of the second water tank 20 and stop deflating the airbag 30 of the first water tank 10;

[0046] S5. Repeat steps S3 and S4 to make water continuously flow through the water tunnel test section 40, thereby realizing the closed-loop operation of the water tunnel test and ensuring the continuity of the water tunnel test.

[0047] In the above-described exemplary embodiment, through the inflation and deflation operations of the airbags 30 in the two water tanks and the switching of the working states of the two three-way valves before and after the water tunnel test section 40, water circulates between the two water tanks, and water continuously flows through the water tunnel test section 40. Thus, the closed-loop operation of the water tunnel is realized by means of air pressure loading, solving the problems of complex water flow direction conversion, poor test stability, and difficult precise control of pressure change in the existing closed-loop water tunnel system due to direct pressurization by a pump. The operation is simple, the operation is stable, and the water flow pressure can be controlled more precisely and smoothly, and the water flow direction can be switched more accurately and quickly, improving the stability, continuity, and reliability of the water tunnel test.

[0048] In some embodiments, in steps S3 and S4, during the deflation process and at the end of deflation of the airbag 30 in the first water tank 10 or the second water tank 20, the air pressure in the airbag 30 is always greater than zero; thereby providing back pressure for the water tunnel test and avoiding adverse conditions such as cavitation.

[0049] In summary, the water tunnel test device and test method of the present invention solve the problems of complex water flow direction conversion, poor test stability, and difficult precise control of pressure change in the existing closed-loop water tunnel system due to direct pressurization by a pump. The closed-loop operation of the air pressure loading type water tunnel test can be realized through the inflation and deflation of the airbag 30 and the switching operation of the two three-way valves before and after the water tunnel test section 40. Its structure is compact, easy to maintain, and applicable to various types of water tunnel tests, especially water tunnel tests with strict requirements for water flow conditions.

[0050] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, and the key points of each embodiment are the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: the specific implementation manners of the present invention can still be modified or some technical features can be equivalently replaced without departing from the spirit of the technical solutions of the present invention, and they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A water tunnel test device, characterized in that: include: The first water tank and the second water tank have air bags in their inner cavities; the two air bags are respectively connected to an external compressed air source via a vent pipe, and a water cavity is formed between each air bag and the inner wall of the water tank where it is located, and each water cavity is filled with water; A water tunnel test section, whose water inlet is connected to the water chambers of the first water tank and the second water tank respectively through a water inlet three-way valve, and whose water outlet is connected to the water chambers of the first water tank and the second water tank respectively through a water outlet three-way valve; the water inlet three-way valve has two inlets and one outlet, the water chamber of the first water tank is connected to one inlet of the water inlet three-way valve through a first drain pipe, the water chamber of the second water tank is connected to the other inlet of the water inlet three-way valve through a second drain pipe, and the water inlet of the water tunnel test section is connected to the outlet of the water inlet three-way valve; the water outlet three-way valve has one inlet and two outlets, the water outlet of the water tunnel test section is connected to the inlet of the water outlet three-way valve, the water chamber of the first water tank is connected to one outlet of the water outlet three-way valve through a first return pipe, and the water chamber of the second water tank is connected to the other outlet of the water outlet three-way valve through a second return pipe; The water tunnel test device is configured to inflate the airbag of the first water tank and deflate the airbag of the second water tank, adjust the working states of the water inlet three-way valve and the water outlet three-way valve, so that the water inlet three-way valve is opened toward the inlet of the first water tank and closed toward the inlet of the second water tank, and the water outlet three-way valve is closed toward the outlet of the first water tank and opened toward the outlet of the second water tank, so that the water in the first water tank flows through the first drain pipe, the water inlet three-way valve, the water tunnel test section, the water outlet three-way valve and the second return pipe in sequence under the inflation pressure and then enters the second water tank until the water volume in the second water tank reaches a preset value; then switch the water inlet three-way valve and the water outlet three-way valve. The working state of the valve is to inflate the air bag of the second water tank and deflate the air bag of the first water tank, so that the water inlet three-way valve is closed toward the entrance of the first water tank and opened toward the entrance of the second water tank, and the water outlet three-way valve is opened toward the outlet of the first water tank and closed toward the outlet of the second water tank, so that the water in the second water tank flows through the second drain pipe, the water inlet three-way valve, the water tunnel test section, the water outlet three-way valve and the first return pipe in sequence under the inflation pressure and then enters the first water tank until the water volume in the first water tank reaches a preset value; the working states of the water inlet three-way valve and the water outlet three-way valve are switched again and the above process is repeated to allow water to continue to flow through the water tunnel test section.

2. The water tunnel test device according to claim 1, characterized in that: The water tunnel test device also includes a water tank and a water supply pump; the water tank is connected to the water cavities of the first water tank and the second water tank respectively through a water injection pipe; the water supply pump is installed on the water injection pipe to pump the water in the water tank into the water cavities of the first water tank and the second water tank.

3. The water tunnel test device according to claim 2, characterized in that: The upper parts of the water chambers of the first water tank and the second water tank are respectively connected to the water storage tank via an overflow pipe; each overflow pipe is provided with a switchable valve.

4. The water tunnel test device according to claim 2, characterized in that: The airbag is a telescopic airbag, the upper end of which is connected to the top of the water tank where it is located, the ventilation tube passes through the top wall of the water tank where the airbag is located and is connected to the airbag, and the lower end of the airbag can move back and forth up and down under the action of internal air pressure and external water pressure.

5. The water tunnel test device according to claim 4, characterized in that: The first water tank and the second water tank are both cylindrical silos. The airbag is cylindrical in shape and can be extended and retracted along the axial direction. The airbag is coaxially arranged with the water tank where it is located.

6. The water tunnel test device according to claim 4, characterized in that: The lower part of the water chamber of the first water tank is connected to the water inlet three-way valve via the first drainage pipe, and is connected to the water outlet three-way valve via the first return pipe; the lower part of the water chamber of the second water tank is connected to the water inlet three-way valve via the second drainage pipe, and is connected to the water outlet three-way valve via the second return pipe.

7. The water tunnel test device according to claim 2, characterized in that: The compressed air source is an air storage tank filled with compressed air.

8. A water tunnel test method, characterized in that: The water tunnel test device according to any one of claims 2 to 7 is used, comprising the following steps: S1, pre-inflate the two airbags respectively, and make the initial air pressure in the first water tank airbag smaller than the initial air pressure in the second water tank airbag; S2, start the water supply pump to pump the water in the water storage tank into the first water tank and the second water tank, and fill the water cavity of the first water tank, the water cavity of the second water tank, the connecting pipe between the first water tank and the water tunnel test section, the connecting pipe between the second water tank and the water tunnel test section, and the water tunnel test section; turn off the water supply pump; S3, inflate the airbag of the first water tank, and deflate the airbag of the second water tank, adjust the working states of the water inlet three-way valve and the water outlet three-way valve, so that the water in the first water tank flows through the water tunnel test section under the inflation pressure and then enters the second water tank, until the water volume in the second water tank reaches a preset value; stop inflating the airbag of the first water tank; S4, switching the working states of the water inlet three-way valve and the water outlet three-way valve, inflating the airbag of the second water tank, and deflating the airbag of the first water tank, so that the water in the second water tank flows through the water tunnel test section under the inflation pressure and then enters the first water tank, until the water volume in the first water tank reaches a preset value; stop inflating the airbag of the second water tank; S5. Repeat steps S3 and S4 to allow water to continue to flow through the water tunnel test section.

9. The water tunnel test method according to claim 8, characterized in that: In steps S3 and S4, the air pressure in the airbag of the first water tank or the second water tank is always greater than zero during the deflation process and at the end of the deflation.

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