Direct measuring device for frictional resistance of underwater wall surface

Abstract

The utility model provides a device and a method for directly measuring the frictional resistance of an underwater wall surface. The device comprises a square pipeline, a cover plate, a sliding block system, a force measuring sensor and a to-be-measured sample piece. The underwater navigation condition is simulated by using the flowing liquid which completely immerses the to-be-tested sample piece. Flowing liquid is introduced into the pipeline, friction resistance is generated between the liquid and the to-be-measured sample piece, the resistance is transmitted to the force measuring sensor through the sliding block system, and then direct measurement of the friction resistance is achieved. By adopting the device and the method for directly measuring the frictional resistance of the underwater wall surface, high-efficiency and high-precision direct measurement of the frictional resistance of an underwater plane or a curved surface can be realized.

Description

Technical Field

[0001] The present application relates to the field of underwater wall friction resistance measurement, and specifically to a direct measurement device and method for underwater wall friction resistance. Background Art

[0002] The measurement device and method of underwater friction resistance has become a research hotspot. Building a device that can directly measure underwater wall friction resistance can provide important technical support for the theoretical and experimental research of underwater drag reduction technology.

[0003] Existing devices and methods for measuring underwater wall friction resistance include direct method and indirect method. Among them, direct methods include: dragging method, whose device size is large and difficult to implement; jet method, which measures friction resistance by spraying liquid onto the surface of the sample to be tested, but there is a big difference from the underwater environment in actual application, so there is a big error in the measurement result. Indirect methods include: rotation method, which converts the relative motion between the sample to be tested and the water flow into rotational motion, which is different from the real scene, so the measurement error is large; pipeline flow method, which measures the liquid pressure difference and then calculates the friction resistance, but this indirect measurement method has a large error and is not suitable for the measurement of micro forces such as millinewton level; optical method: friction resistance is calculated by measuring the displacement of the platform carrying the sample to be tested. Affected by the processing accuracy and assembly accuracy of the platform, this indirect measurement method is difficult to implement and has a large error.

[0004] In summary, due to the problems of the direct method, such as large device size and large deviation from the actual situation, the indirect method is mostly used to measure underwater wall friction resistance, that is, the friction resistance is calculated by measuring parameters such as torque, pressure difference, displacement, etc. However, the indirect method still has problems such as large errors, cumbersome calculation process, and complex calibration process. There is still a lack of simple devices and accurate measurement methods that can simulate the real flow field environment and directly measure the underwater wall friction resistance. Summary of the invention

[0005] Based on this, the present application provides a direct measurement device and method for underwater wall friction resistance, which uses flowing liquid that completely immerses the test sample to simulate the underwater navigation conditions of the aircraft, and can directly measure the friction resistance encountered by the test sample in the flowing water.

[0006] A direct measurement device for underwater wall friction resistance, characterized by comprising: a square pipe, a cover plate, a slider system, a force sensor, and a sample to be measured.

[0007] In the embodiment of the present application, an opening is provided on the pipe wall of the square pipe, and the cover plate is placed at the opening and connected to the pipe wall by bolts.

[0008] In the embodiment of the present application, the cover plate further includes:

[0009] A groove for accommodating a slider system;

[0010] A first circular hole is provided at the center of the bottom surface of the groove and is used for passing the curved rod;

[0011] An annular groove is provided on the connecting surface of the cover plate and is used for placing a sealing strip;

[0012] In the embodiment of the present application, the slider system further includes:

[0013] A slider, used for placing the sample to be tested, and provided with a second circular hole, wherein the second circular hole has the same axial position as the first circular hole, and the diameter of the first circular hole is larger than the diameter of the second circular hole;

[0014] A curved rod, one end of which is inserted into the first circular hole and the second circular hole at the same time, and the other end of which is connected to the force sensor to transmit the friction resistance between the sample to be tested and the water;

[0015] A sealing ring, used for sealing the gap between the first circular hole and the curved rod;

[0016] A filling block, used to control the sliding range of the slider in the groove;

[0017] A bearing, disposed on the slider, so that the slider can slide in the groove;

[0018] A bearing limiter, disposed in the groove, for limiting the bearing from sliding in the groove;

[0019] The gasket group is a combination of multiple gaskets of different thicknesses, which is installed on the upper surface of the slider and is used to adjust the height of the sample to be tested.

[0020] In one embodiment, the surface to be tested of the sample to be tested is a plane or a curved surface.

[0021] The present application discloses a method for directly measuring underwater wall friction resistance, which is applied to the direct measurement system for underwater wall friction resistance described in any of the above embodiments, comprising:

[0022] After the flowing liquid is introduced into the square pipe, the sample to be tested and the sliding block are completely immersed in the liquid;

[0023] The friction resistance between the sample to be tested and the water is transmitted to the force sensor through the slider system;

[0024] By acquiring the measurement data of the force sensor, the friction resistance between the test surface of the test sample and water can be obtained.

[0025] By using the gasket sets with different thicknesses, the height of the sample to be tested is adjusted.

[0026] The advantages of this application are:

[0027] The present application provides a direct measurement device and method for underwater wall friction resistance, the device includes a square pipe, a cover plate, a slider system, a force sensor, and a sample to be tested. The water environment of a vehicle sailing in water is simulated by using flowing water that completely immerses the sample to be tested, and the friction resistance of the sample to be tested in the flowing liquid is directly measured. Compared with other devices and methods for measuring friction resistance, it has the advantages of simple device, convenient replacement of samples to be tested, high measurement efficiency, high measurement accuracy, etc., and can achieve the measurement of millinewton-level friction resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0029] Figure 1 is a schematic diagram of the overall layout of a direct measurement device for underwater wall friction resistance in one embodiment;

[0030] Figure 2 is a cross-sectional schematic diagram of a device for directly measuring underwater wall friction resistance in one embodiment;

[0031] Figure 3 is a schematic diagram of the overall layout of a direct measurement device for underwater wall friction resistance in one embodiment;

[0032] Figure 4 The diagram is a schematic diagram of a cover plate of a device for directly measuring underwater wall friction resistance in one embodiment.

[0033] in:

[0034] 1-square pipe; 2-cover plate; 3-slider; 4-gasket set; 5-bent rod; 6-sealing ring; 7-force sensor; 8-filling block; 9-sample to be tested; 10-bearing; 11-bearing limiter; 12-sealing strip. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application are described in detail below in conjunction with the accompanying drawings. However, the described embodiments are only some embodiments of the present application, not all embodiments. In addition to the described embodiments, the present application can also be implemented in many ways different from the embodiments described here, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific implementation disclosed below.

[0036] like Figure 1 , Figure 2 , Figure 3 , Figure 4 As shown, in the embodiment of the present application, a direct measurement device and method of underwater wall friction resistance includes a square pipe 1, a cover plate 2, a slider system, a force sensor 7, and a sample to be measured 9. An opening is provided on the pipe wall of the square pipe 1, and the cover plate 2 is placed at the opening and connected to the pipe wall by bolts.

[0037] The cover plate 2 includes a groove for placing the slider system; a first circular hole, arranged at the center of the bottom surface of the groove, for passing the curved rod 5; and an annular groove, arranged on the connecting surface of the cover plate 2, for placing the sealing strip 12.

[0038] The slider system includes a slider 3, which is used to place the sample 9 to be tested and is provided with a second circular hole, the second circular hole is at the same axial position as the first circular hole, and the diameter of the first circular hole is larger than the diameter of the second circular hole; a curved rod 5, one end of which is inserted into the first circular hole and the second circular hole at the same time, and the other end of the curved rod 5 is connected to the force sensor 7, which is used to transmit the friction resistance between the sample 9 to be tested and water; a sealing ring 6, which is used to seal the gap between the first circular hole and the curved rod 5; a filling block 8, which is used to control the sliding range of the slider 3 in the groove; a bearing 10, which is arranged on the slider 3 so that the slider 3 can slide in the groove; a bearing limiter 11, which is arranged in the groove, and is used to limit the sliding of the bearing 10 in the groove; a gasket group 4, which is a combination of multiple gaskets of different thicknesses, installed on the upper surface of the slider 3, and is used to adjust the height of the sample 9 to be tested.

[0039] Specifically, the square pipe 1 can be a pipe container that can hold liquid and has an opening on one side wall, including flanges at both ends that can be connected to an external system, and the liquid held is water. The present application does not specifically limit the size and material of the square pipe. Exemplarily, the square pipe 1 can be a pipe with a length of 1000mm, a wall thickness of 10mm, a water-passing cross-section of 24x 24mm square, and a 20x 80mm opening on one side wall. By passing flowing liquid into the pipe, the working conditions of the sample to be tested in actual application can be more realistically simulated. The embodiment of the present application does not specifically limit the shape and material of the sample to be tested 9. Exemplarily, the sample to be tested 9 can be a sample with a curved surface to be tested.

[0040] In the embodiment of the present application, the sealing ring 6 is a sealing component that can seal the gap between the curved rod 5 and the first circular hole and has minimal effect on the transmission of friction resistance. Under the above requirements, the embodiment of the present application does not make specific requirements on the shape and material of the sealing ring. For example, the sealing ring 6 can be a thin soft rubber film.

[0041] A direct measurement method of underwater wall friction resistance according to an embodiment includes:

[0042] After the flowing liquid is introduced into the square pipe 1, the sample to be tested and the slider 3 are completely immersed in water;

[0043] In the embodiment of the present application, the friction resistance between the sample to be tested 9 and the water is transmitted to the force sensor 7 through the slider system;

[0044] By acquiring the measurement data of the force sensor 7 , the friction resistance between the test sample 9 and water can be obtained.

[0045] By using the gasket set 4 with different thicknesses, the height of the sample 9 to be tested is adjusted.

[0046] The overall workflow of the direct measurement method of underwater wall friction resistance described in one embodiment is described as follows:

[0047] 1. Glue the sample to be tested onto the slider 3 and select a gasket set 4 of corresponding size according to the initial height of the sample to be tested required for the test.

[0048] 2. Connect the bearing to the slider 3, and then push the slider 3 into the groove of the cover plate 2;

[0049] 3. Pass one end of the curved rod 5 through the first circular hole and connect it to the second circular hole on the slider 3;

[0050] 4. Install the filling block 8 and adjust the sliding range of the slider 3;

[0051] 5. Connect the cover plate 2 to the square pipe 1;

[0052] 6. Connect the square pipe 1 to the external system;

[0053] 7. A flowing liquid is introduced, and the friction resistance between the surface of the sample 9 to be tested and the water is transmitted to the force sensor 7 through the slider system. By acquiring the measurement data of the force sensor 7, the friction resistance can be obtained;

[0054] 8. Turn off the flowing water and release the water in the square pipe 1;

[0055] 9. Loosen the bolts, remove the cover plate 2, and replace or remove the sample 9 to be tested.

Claims

1. A direct measurement device for underwater wall friction resistance, characterized in that: include: A square pipe (1), a cover plate (2), a slider system, a force sensor (7), and a sample to be tested (9), wherein the square pipe (1) is used to contain a flowing liquid, wherein the liquid is water. An opening is provided on the pipe wall of the square pipe (1), and the cover plate (2) is placed at the opening and connected to the pipe wall by bolts. The cover plate (2) comprises: a groove for accommodating the slider system; a first circular hole, which is arranged at the center of the bottom surface of the groove and is used to pass a curved rod (5); and an annular groove, which is arranged on the connecting surface of the cover plate (2) and is used to place a sealing strip (12). The slider system comprises: a slider (3) for accommodating the sample to be tested (9), and is provided with a second circular hole, wherein the second circular hole has the same axial position as the first circular hole, and the diameter of the first circular hole is larger than the diameter of the second circular hole. a curved rod (5), one end of which is inserted into the first circular hole and the second circular hole at the same time, and the other end of which is connected to the force sensor (7) for transmitting the friction resistance between the sample to be tested (9) and water; a sealing ring (6) for sealing the gap between the first circular hole and the curved rod (5); a filling block (8) for controlling the sliding range of the slider (3) in the groove; a bearing (10) arranged on the slider (3) so that the slider (3) can slide in the groove; a bearing limiter (11) arranged in the groove for limiting the sliding of the bearing (10) in the groove; and a gasket group (4) which is a combination of multiple gaskets of different thicknesses, mounted on the upper surface of the slider (3) and used to adjust the height of the sample to be tested (9).

2. A direct measurement device for underwater wall friction resistance as claimed in claim 1, characterized in that: The surface to be tested of the sample (9) to be tested is a plane or a curved surface.

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