An indoor annular wind erosion test device

Abstract

The present invention relates to an indoor annular wind erosion test device, comprising: a main test track for simulating wind erosion, which is a circular closed structure with a rectangular cross-section and contains a cavity. The sample moves in the cavity. A speed sensor, a temperature sensor and an image capture device are arranged in the main test track. The image capture device is a high-speed camera system installed in the sample container to monitor and feedback the motion posture of the sample, and the servo motor is controlled and adjusted by a microcomputer to provide a stable output power; an outer track and an inner track located on both sides above the main test track, which are circular structures. The width of the cavity is the same as the diameter of the steel ball, and only one row of steel balls can be placed; a transmission rod is connected to the servo motor through a semi-flexible joint, and the other end is connected to the sample container. Steel ball grooves are arranged at the joints with the outer track and the inner track, and are matched and fitted with the steel balls; a sample container, which includes a multi-degree-of-freedom connection device and an air filter screen.

Description

Technical Field

[0001] The present invention relates to the technical field of material testing, and particularly relates to an indoor annular wind erosion test device. Background Art

[0002] The erosion of the earth's surface by wind and sand in nature is very strong and is of great significance to the formation of landforms. In addition, the phenomenon of wind and sand erosion also has an adverse impact on engineering facilities. Long-term wind and sand erosion causes grooves to appear on the surface layer of slopes, which in turn promotes the process of weathering and induces many geological disasters. At the same time, wind and sand will also cause certain erosion to building structures, which is particularly obvious in some concrete structures and masonry structures. However, at present, the design and protection of engineering facilities pay more attention to mechanical stability and rarely focus on wind and sand erosion. In actual engineering, it is found that wind and sand erosion is a key factor promoting the development of disasters. Especially in the loess slopes in arid and semi-arid regions and the high-steep rock slopes crossing river valleys, the wind action even becomes the main factor inducing natural disasters. Therefore, it is very necessary and significant to study the impact of wind erosion on rock and soil masses.

[0003] At present, the test devices related to wind erosion are mainly linear, mostly with large floor areas and complex operation and use, far beyond the scope of use in the geological field. In the simulation of wind and sand erosion in the geological field, the erosion process and results have very important values, but there are no clear restrictions on the requirements for the erosion object, and it can be scaled down proportionally. This means that when conducting wind and sand erosion tests on rock and soil masses, a small-scale wind erosion test system can be used, which requires the test system to have the following characteristics: convenient operation, simple wind speed conditions, low cost, etc. Summary of the Invention

[0004] The present invention relates to an indoor annular wind erosion test device. By setting an annular channel, the floor area is reduced. By changing the shapes of different filters, different wind speeds and wind directions can be controlled, and the effect of wind erosion on small rock and soil masses can be achieved.

[0005] An indoor annular wind erosion test device includes:

[0006] A main test channel for simulating wind erosion, which is a circular closed structure with a rectangular cross-section and contains a cavity. The sample moves in the cavity. A speed sensor, a temperature sensor and an image capture device are arranged in the main test channel. The image capture device is a high-speed camera system installed in the sample container to monitor and feedback the movement posture of the sample, and the servo motor is controlled and adjusted by a microcomputer to provide a stable output power;

[0007] The servo motor is connected to the sample container through a four-way connection device at the top and a force transmission rod, directly controlling the rotation of the sample; the supports are arranged at the four arc tops of the main test track, used to support the entire test system, and their height is the same as that of the servo motor; the cylindrical solid transmission rod is used to connect the motor and the four-way connection device; the four-way connection device is disc-shaped, and connection channels for connecting the force transmission rods are arranged in four mutually perpendicular directions; the semi-flexible joint is used to connect the four-way connection device and the force transmission rod, providing semi-flexible constraints to prevent the rigid material from breaking during overload;

[0008] The outer track and the inner track located on both sides above the main test track are annular structures, and the cavity width is the same as the diameter of the steel balls, only allowing one row of steel balls to be placed; the force transmission rod is connected to the servo motor through a semi-flexible joint, and the other end is connected to the sample container. A steel ball groove is arranged at the connection with the outer track and the inner track, and is fitted with the steel balls;

[0009] The sample container includes: a multi-degree-of-freedom connection device and an air filter. The air filters with different pore sizes are used to prevent sample debris from falling into the test air duct and changing the wind force conditions.

[0010] Furthermore, the indoor annular wind erosion test device is externally connected to a water tank and internally provided with an atomizer to realize wind erosion simulation under rainfall conditions.

[0011] The beneficial technical effects achieved by the present invention:

[0012] (1) By using a servo motor to drive the rotation of the sample, the speed change can be accurately controlled through the computer terminal, and the wind erosion test of the sample is carried out through relative movement. Compared with traditional direct wind erosion, it is more accurate and controllable.

[0013] (2) By setting up a multi-channel connection device, multi-sample tests can be realized simultaneously, greatly saving the test time.

[0014] (3) The sample is connected to the motor through a force transmission rod and placed above the main test track. The rotation friction is reduced through the inner and outer bearing tracks, which can effectively ensure the overall uniformity and integrity of the test track and provide a stable wind speed for the sample.

[0015] (4) The annular test structure can greatly reduce the test land area.

[0016] (5) In order to address the problem of insufficient motor power, air filters of different shapes are used to achieve the purpose of amplifying the wind speed. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of the indoor annular wind erosion test device;

[0018] Figure 2 It is a top view of the indoor annular wind erosion test device;

[0019] Figure 3 It is a schematic diagram of a sample container;

[0020] Figures 4(a) to 4(c) It is a schematic diagram of air filters with different pore sizes;

[0021] Figure 5 It is a characteristic diagram of the visualized airflow movement obtained by analyzing and calculating air filters in different forms.

[0022] Among them: 1 - main test track; 2 - servo motor; 3 - support; 4 - transmission rod; 5 - coupling device; 6 - semi-flexible joint; 7 - outer track; 8 - inner track; 9 - force transmission rod; 10 - ball bearing; 11 - sample container; 12 - ball groove; 13 - multi-degree-of-freedom coupling device; 14 - air filter; 15 - detachable test window; 16 - external multi-functional interface. Specific implementation mode

[0023] The following further elaborates on an indoor annular wind erosion test device of the present invention in conjunction with the accompanying drawings and specific embodiments.

[0024] Embodiment:

[0025] In order to simulate the natural wind and sand erosion environment, the present invention proposes an indoor annular wind erosion test device, which is of an overall annular structure and occupies a small area. By changing the rotation speed of the servo motor, it can simulate wind force tests under different wind speeds and different airflow states. The test area is a cube with dimensions of 10 cm × 10 cm × 10 cm. The sample preparation is simple, and it can be applied to concrete erosion resistance tests, rock and soil body wind erosion resistance tests, and wind erosion resistance tests for surface protection of rock and soil bodies, etc.

[0026] It includes a main test track 1, which provides a test channel for simulating wind erosion. The overall structure is a circular closed structure with a rectangular cross-section and a cavity, and the sample moves in the cavity. A speed sensor, a temperature sensor and an image capture device are arranged in the test track. The image capture device is a high-speed camera system installed in the sample container 11, which is used to monitor and feedback the movement posture of the sample, and adjust the servo motor 2 through microcomputer control to provide a stable output power; the servo motor 2 can be controlled by a microcomputer and is connected to the sample container 11 through a four-way connection device 5 and a force transmission rod 9 at the top to directly control the rotation of the sample; the supports 3 are respectively arranged at the four arc tops of the main test track to support the entire test system, and their heights are the same as those of the servo motor; the transmission rod 4 is used to connect the motor and the connection device, and is made of solid cylindrical precision steel with strong torque resistance; the connection device 5 is disc-shaped and is provided with connection channels in four mutually perpendicular directions for connecting the force transmission rods; the semi-flexible joint 6 is used to connect the connection device and the force transmission rod to provide semi-flexible constraints to prevent the sudden fracture of rigid materials during overload and protect the test system; the outer track 7 and the inner track 8 are located on both sides above the main test track and are annular structures. The cavity width is the same as the diameter of the steel balls, and only one row of steel balls 10 can be placed; the force transmission rod 9 is connected to the servo motor 2 through the semi-flexible joint 6 and the connection device 5, and the other end is connected to the sample container 11. Steel ball grooves 12 are arranged at the joints with the inner and outer tracks 7 and 8 to match and fit with the steel balls 10; the sample container 11 is composed of multiple components and is mainly used to accommodate and protect the sample. It includes a multi-degree-of-freedom connection device 13 and an air filter 14. The air filter 14 mainly has two functions: preventing sample debris from falling into the test air duct and changing the wind conditions. According to different pore sizes, it is divided into three types of filters. Under the condition that the servo motor 2 provides a stable output power, by changing the filter type, different wind condition requirements can be met; the detachable test window 15 can place the sample, clean the test area and observe the test dynamics; the external multi-functional interface 16 can be externally connected to moisture, and an atomizer is installed inside to realize the simulation of wind erosion under rainfall conditions.

[0027] Conventional wind erosion test

[0028] 1. Check and preheat the machine before the test;

[0029] 2. Open the detachable test window 15;

[0030] 3. Manually rotate the connection device 5 along the rotation direction of the motor, move the four sample containers 11 to the transparent door respectively, and place the samples from the side;

[0031] 4. After placing the samples, replace the air filter according to actual needs. Then close the test window, confirm the seal, and prepare to start the test;

[0032] 5. Check whether the connection device 5 and the semi-flexible joint 6 are connected to ensure no looseness;

[0033] 6. Check whether all the steel balls 10 are located in the inner and outer tracks. At the same time, check whether the steel ball grooves 12 are fully engaged with the steel balls. After meeting the safety conditions, turn on the power supply to prepare for the test;

[0034] 7. Turn on the servo motor, preset the initial speed, and gradually increase the engine speed through a linear relationship until the preset speed is reached;

[0035] 8. After the test starts, use the sensor to record the speed change and temperature change in real time, capture the specimen photos according to the test plan, and store them in real time;

[0036] 9. According to the test plan, after reaching the target, gradually reduce the engine speed. After stopping the test, open the test window, take out the sample and clean the sample container.

[0037] Wind Erosion Test under Rainfall Conditions

[0038] 1. Check and preheat the machine before the test;

[0039] 2. Open the detachable test window 15;

[0040] 3. Manually rotate the coupling device 5 in the direction of the motor rotation, move the four sample containers 11 to the transparent door respectively, and place the samples from the side;

[0041] 4. After placing the samples, replace the air filter according to actual needs. Then close the test window, confirm the seal, and prepare to start the test;

[0042] 5. Check whether the coupling device 5 and the semi-flexible joint 6 are connected to ensure no looseness;

[0043] 6. Check whether all the steel balls 10 are located in the inner and outer tracks. At the same time, check whether the steel ball grooves 12 are fully engaged with the steel balls. After meeting the safety conditions, turn on the power supply to prepare for the test;

[0044] 7. Connect the water tank to the external multi-functional interface 16, and adjust the water inflow and atomization degree by adjusting the valve;

[0045] 8. Turn on the servo motor, preset the initial speed, and gradually increase the engine speed through a linear relationship until the preset speed is reached;

[0046] 9. After the test starts, use the sensor to record the speed change, temperature and humidity change in real time, capture the specimen photos according to the test plan, and store them in real time;

[0047] 10. According to the test plan, after reaching the target, gradually reduce the engine speed. After stopping the test, open the test window, take out the sample and clean the sample container, and dry the main test track.

[0048] To further elaborate on the wind speed characteristics of the wind erosion model, the Fluent module of the numerical simulation software ANSYS was used to analyze and calculate air filters of different forms based on the theory of fluid mechanics, and the visualized motion characteristics of the air flow were obtained ( Figure 5 ). During the calculation, a part of the main test track was intercepted, boundary conditions, wind direction, and wind speed were set, and the wind speed changes under the influence of air filters of different forms were considered. Numerical simulation calculations were carried out for the three filters in Figure 4. The aperture of the single-hole filter is 5 cm, the single-circle aperture of the four-hole filter is 2.5 cm, and the single-circle aperture of the sixteen-hole filter is 1.25 cm.

[0049] In a uniform main air duct, the air flow shows laminar flow characteristics with a uniform speed. When a wind speed filter is placed in the air duct, the air flow becomes turbulent, converges behind the filter, and is compressed after passing through the filter, resulting in a faster wind speed. It can be seen that under the influence of wind speed filters of different forms, the speed and state of the air flow will change. The more holes there are, the greater the change in the air flow, and the stronger the erosion effect it produces.

[0050] By establishing the relationship between the engine speed n, the actual speed v, and the wind speed vw, the wind speed conditions at different servo motor speeds can be achieved.

[0051] According to the traditional wind erosion test method, the surface of the sample is directly eroded by the wind, and the wind speed is the same as the output wind speed. In the present invention, the use of engine work to make the sample move in the test track, thereby generating wind force, belongs to an indirect type of wind erosion test and requires a certain conversion:

[0052]

[0053] In Equation (1), w represents the angular velocity of the sample; r represents the length of the force transmission rod; the actual speed v of the sample can be obtained through calculation.

[0054] In circular motion, the angular velocity inside and outside is the same. n is the engine speed and v is the sample speed. Obviously, the sample speed is 2πr times the engine speed and depends on the length of the force transmission rod. Therefore, the purpose of amplifying the wind speed can be achieved by increasing the length of the force transmission rod.

[0055] However, in actual motion, the speed of the sample does not represent the wind speed. Therefore, according to the law of conservation of energy during the motion process, the wind speed generated by a sample of fixed mass during the motion process can be deduced:

[0056] P·t = F·s t +Q (2)

[0057] In Equation (2), P represents the power of the engine, F represents the wind resistance during the motion of the sample, st represents the displacement of the sample per unit time, and Q represents the heat work done by the entire system, mainly generated by the heat release of the engine work.

[0058] According to Newton's second law, the resistance of the sample affected by the wind speed is:

[0059]

[0060] where m is the mass of the sample.

[0061] Also, the sample is moving in a uniform circular motion, so:

[0062] s t = vt (4)

[0063] Substituting equations (3) and (4) into equation (2), it can be deduced that:

[0064] P·t = mv w ·v + Q (5)

[0065] Furthermore, the wind speed can be obtained as:

[0066]

[0067] The above has described the embodiments of the present invention in detail with reference to examples. However, the present invention is not limited to the above examples. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes made without departing from the gist of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. An indoor annular wind erosion test device, characterized in that, Comprising: A main test track for simulating wind erosion, which is a circular closed structure with a rectangular cross-section and contains a cavity. The sample moves in the cavity. A speed sensor, a temperature sensor, and an image capture device are arranged in the main test track. The image capture device is a high-speed camera system installed in the sample container to monitor and feedback the movement posture of the sample, and the servo motor is controlled and adjusted by a microcomputer to provide a stable output power; A servo motor, which is connected to the sample container through a four-way connection device and a force transmission rod at the top to directly control the rotation of the sample; a support, which is arranged at the four arc tops of the main test track to support the entire test system, and its height is the same as that of the servo motor; a cylindrical solid transmission rod is used to connect the motor and the four-way connection device; the four-way connection device is disc-shaped, and connection channels for connecting the force transmission rods are arranged in four mutually perpendicular directions; a semi-flexible joint is used to connect the four-way connection device and the force transmission rod to provide semi-flexible restraint to prevent the rigid material from breaking during overload; An outer track and an inner track located on both sides above the main test track, which are circular structures. The cavity width is the same as the diameter of the steel balls, and only one row of steel balls can be placed; the force transmission rod is connected to the servo motor through a semi-flexible joint, and the other end is connected to the sample container. Steel ball grooves are arranged at the joints with the outer track and the inner track to match and fit with the steel balls; A sample container, comprising: a multi-degree-of-freedom connection device and an air filter. Air filters with different pore sizes are used to prevent sample debris from falling into the test air duct and changing the wind force conditions.

2. The indoor annular wind erosion test device according to claim 1, characterized in that, The indoor circular wind erosion test device is externally connected to a water tank and internally provided with an atomizer to realize wind erosion simulation under rainfall conditions.

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