Mesh tension test device and method and mesh tension prediction method

Abstract

The invention discloses a mesh tension test device which comprises a water tank, a water pump, a mesh, a tension sensor, a mounting foundation and a plurality of wet viscose fiber towels, the specific strength of the wet viscose fiber towel is 8.0 to 13.5 N.m / g. The invention further provides a mesh tension test method which is realized through the mesh tension test device. The invention further provides a mesh tension prediction method, and the tension borne by the mesh is predicted through a mesh tension formula. According to the technical scheme, the wet viscose fiber towel is used for replacing the jellyfish to simulate the biological blocking effect in the test, the test device is simple in structure, the test method is simple and easy to implement, the blocking characteristic of the jellyfish in the trash holding net can be effectively simulated, and the influence of the jellyfish on the pull force of the trash holding net is evaluated. Through the mesh tension prediction method, the influence of each variable on the tension can be quantified, and a theoretical basis is provided for how to reasonably select the mesh aperture, flow velocity control and the like in engineering design.

Description

Technical Field

[0001] The invention relates to a mesh tension test device and method based on simulated jellyfish and a mesh tension prediction method, relates to a tension test of a trash net under biological clogging conditions, and belongs to the field of water conservancy engineering and nuclear power cold source protection. Background Art

[0002] The cold source pollution interception net of a nuclear power plant is an important facility used in the cooling water system of a nuclear power plant. It is mainly used to draw water from nearby water bodies (such as rivers, lakes or oceans) to provide cooling water for the cooling system of the reactor. The main function of the cold source pollution interception net is to filter out impurities and biological matter in the water, ensuring that large substances in the water body (such as fish, plants and other floating objects) do not enter the cooling system, causing equipment damage or affecting cooling efficiency. The mesh size of the cold source pollution interception net is usually designed to be able to intercept impurities larger than particulate matter in the water flow, while minimizing resistance to the water flow. In addition, the cold source pollution interception net is usually made of corrosion-resistant metal materials, such as stainless steel or alloy materials, to ensure its long-term and stable operation in harsh water environments.

[0003] During the operation of the pollution control net of the cold source of nuclear power plants, there are often a large number of marine organisms such as jellyfish, which leads to increased resistance of the mesh and increased tensile load. The tensile test of the pollution control net is a key test of the pollution control net and its supporting structure. The main purpose is to verify the strength and stability of the pollution control net when it is subjected to external forces in actual use. Through the tensile test, it can be ensured that the pollution control net will not be deformed or broken due to excessive force during long-term operation, thereby ensuring the normal operation of the cooling system.

[0004] The traditional tensile test of the trash net uses jellyfish for simulation test, but due to the limited jellyfish resources, it cannot fully support the relevant test needs, and the difficulty in obtaining and preserving jellyfish affects the repeatability and convenience of the test. Therefore, it is urgent to find a convenient and replaceable material to simulate the clogging effect of jellyfish on the trash net. Summary of the invention

[0005] Therefore, the object of the present invention is to provide a mesh tensile testing device, method and mesh tensile prediction method, which performs a mesh tensile test by simulating jellyfish, and the test results can predict the tensile force that the mesh will withstand under different mesh pore sizes, different flow rates and different blockage rates.

[0006] In order to achieve the above object, a mesh tensile test device of the present invention comprises:

[0007] sink;

[0008] A water pump, used to drive the water flow along the flume;

[0009] The mesh is arranged on the cross section of the water tank, and comprises a mesh frame and a mesh body fixed on the mesh frame;

[0010] A tension sensor is arranged at an upstream position of the mesh and connected to the mesh via a pull rope;

[0011] An installation base, used for installing the tension sensor;

[0012] A plurality of wet viscose fiber towels are used to simulate jellyfish being blocked by a mesh; the specific strength of the wet viscose fiber towels is 8.0-13.5 N·m / g.

[0013] The wet viscose fiber towel is circular and can be attached to the upstream side of the net body.

[0014] There are multiple pull ropes, and the multiple pull ropes are connected to the net frame.

[0015] The installation base comprises a vertical pole which is vertically inserted downward into the water tank, a traction rope is arranged on the vertical pole, and the tension sensor is connected to the traction rope.

[0016] The present invention also provides a mesh tensile test method, which is implemented by the mesh tensile test device as described above, comprising:

[0017] The water in the water tank is driven to flow at a preset flow rate by a water pump;

[0018] A number of wet viscose fiber towels are applied to the upstream side of the net body according to a preset blocking rate, wherein:

[0019]

[0020] The tension applied to the mesh is obtained through a tension sensor.

[0021] The present invention also provides a mesh tension prediction method, which is predicted by the following mesh tension formula:

[0022] F=(-63.33679D+260.62564)Av (―0.07564D+1.7239) (1+(-1.33738D+29.70798)β (―0.262D+2.64244) )

[0023] Among them, F is the tension on the mesh, A is the mesh area, v is the flow velocity, β is the blockage rate; and D is the pore size of the mesh.

[0024] Through the mesh tensile test method described above, multiple test data of the tensile force borne by the mesh under different mesh apertures, different flow rates and different blockage rates were obtained, and the following formula was obtained by fitting the data using a model based on the Morrison equation:

[0025] F=k1Avn (1+k2β m )

[0026] The experimental data was formed into a matrix and brought into Matlab for least squares fitting to obtain the fitting formula coefficient table. According to the changes in aperture and coefficient, the relationship between coefficient and aperture was linearly fitted again to obtain the relationship between four coefficients and aperture:

[0027] k1=―63.33679D+260.62564

[0028] k2=-1.33738D+29.70798

[0029] n=―0.07564D+1.7239

[0030] m=―0.262D+2.64244

[0031] Thus, the mesh tension formula is obtained.

[0032] By adopting the above technical scheme, the mesh tension test device and method of the present invention use wet viscose fiber towels to replace the biological clogging effect in the jellyfish simulation test. The test device has a simple structure and the test method is simple and easy to use. It can effectively simulate the clogging characteristics of jellyfish in the trash net and evaluate its influence on the tension of the trash net. This method can be extended to related units for biological clogging tests in nuclear power plants and other water-related projects to solve the problem of insufficient jellyfish resources in the laboratory. The mesh tension prediction method of the present invention can not only quantify the influence of various variables on tension, but also provide a theoretical basis for how to reasonably select mesh aperture, flow rate control, etc. in engineering design. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the mesh tensile testing device of the present invention.

[0034] Figure 2 This is a comparison chart of the tensile test of wet viscose fiber towel and jellyfish.

[0035] Figure 3 The graphs show the variation of tension of meshes with different apertures as the blockage rate changes, where (a) is the variation of tension of meshes with an aperture of 1 cm, (b) is the variation of tension of meshes with an aperture of 2 cm, and (c) is the variation of tension of meshes with an aperture of 3 cm.

[0036] Figure 4 These are the tensile test data and formula verification diagrams for meshes with different apertures, where (a) is the test data and formula verification diagram for 1 cm aperture, (b) is the test data and formula verification diagram for 2 cm aperture, and (c) is the test data and formula verification diagram for 3 cm aperture. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below through the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, the present invention provides a mesh tension test device, including a water tank 1, a water pump (not shown in the figure), a mesh 2, a tension sensor 3, an installation base and a plurality of tense viscose fiber towels. The cross section of the water tank 1 can be square or circular, and the water pump is used to drive the water flow from one end to the other end along the direction of the water tank 1 to simulate the flow of seawater. The mesh 2 is arranged on the cross section of the water tank 1, including a net frame 21 and a net body 22 fixed on the net frame 21. The tension sensor 3 is arranged at the upstream position of the mesh 2 and is connected to the mesh 2 by a pull rope 4. The installation base is used to install the tension sensor 3, including a vertical pole 5 inserted vertically downward into the water tank, a traction rope 6 is arranged on the vertical pole 5, and the tension sensor 3 is connected to the traction rope 6. The wet viscose fiber towel 7 is used to simulate the jellyfish being blocked by the mesh, and it can be attached to the upstream side of the net body 22. In this embodiment, the cross-section of the water tank 1 is square, the mesh frame 21 of the mesh sheet 2 is a square frame, and there are a plurality of pull ropes 4 , which are connected to the mesh frame 21 .

[0039] The specific strength of the wet viscose fiber towel is 8.0-13.5 N·m / g, and the preferred embodiment is 11 N·m / g. Compared with the real jellyfish test, the test is carried out at a flow rate of 0.1 m / s and a blockage rate of 28.8%, and the water flow force (i.e., the tension collected by the tension sensor) of a 0.5 mm pore size is tested. Figure 2 Specifically, the ordinate represents the force of the water flow, and the abscissa represents the time when the jellyfish and the wet viscose fiber towel are placed in the water. The force trend of the wet viscose fiber towel quickly tends to coincide with that of the real jellyfish within a short period of time after the release, and then remains stable. This shows that in long-term pollution-blocking net tests, the wet viscose fiber towel can be used as a substitute for jellyfish to simulate the force of jellyfish in the net bag. Therefore, based on the test results of the wet viscose fiber towel, this test infers that it is reasonable and well-founded to use wet paper towels to calculate and evaluate the force characteristics of the pollution-blocking net.

[0040] The experiment used a 16m×0.5m×0.6m water trough and a 0.5m×0.5m square mesh, with a water depth of 0.5m, a water salinity of 30‰, and a water temperature of 25℃~29℃.

[0041] Test conditions: The test flow rate was set at three levels: 0.1m / s, 0.2m / s and 0.3m / s; in order to obtain the mesh tension results under different apertures, the test mesh used the mesh with apertures of 1cm, 2cm and 3cm that are currently commonly used on site. The test conditions are shown in Table 1.

[0042] Table 1 Test conditions

[0043]

[0044]

[0045] The wet viscose fiber towel can be set in a circular shape or in other shapes. The area of ​​the mesh used in the test is 2500cm 2 , a wet viscose fiber towel is used to simulate jellyfish to block the mesh. Multiple wet viscose fiber towels can be set for different blocking rates, including:

[0046]

[0047] During the test, the water in the water tank is driven by a water pump to flow at a preset flow rate, and a number of wet viscose fiber towels are applied to the upstream side of the mesh according to the preset blockage rate. The tension value of the mesh is obtained by the tension sensor. Figure 3 .

[0048] In the process of studying how the tension on the mesh changes with flow rate, pore size and blockage rate, it was found that the resistance of the fluid through the mesh is significantly affected by the three factors. In order to more accurately describe the force of the mesh under different working conditions, a model based on the Morrison equation was used for data fitting. The Morrison equation is widely used in fluid dynamics and can better reflect the force of the fluid on the structure. On this basis, a regression analysis was performed on the experimental data to obtain a fitting formula that can describe the change of tension with flow rate, pore size and blockage rate. This formula can not only quantify the influence of each variable on the tension, but also provide a theoretical basis for how to reasonably select the mesh pore size, flow rate control, etc. in engineering design. The formula is as follows:

[0049] F=k1Av n (1+k2β m )……(1)

[0050] Among them, F is the tension on the mesh, A is the mesh area, v is the flow velocity, and β is the blockage rate.

[0051] The test data is formed into a matrix and brought into Matlab for least squares fitting. The results are shown in Table 2:

[0052] Table 2 Fitting formula coefficient table

[0053] Aperture(cm) <![CDATA[k1]]> <![CDATA[k2]]> n m 1cm 198.33843 28.78639 1.66919 2.24983 2cm 131.85290 26.20165 1.53075 2.37967 3cm 71.66485 26.11164 1.51791 1.72583

[0054] According to the changes of aperture and coefficient, the relationship between coefficient and aperture is linearly fitted again to obtain four relationships between coefficient and aperture:

[0055] k1=―63.33679D+260.62564

[0056] k2=-1.33738D+29.70798

[0057] n=―0.07564D+1.7239

[0058] m=―0.262D+2.64244

[0059] Where D is the aperture of the mesh.

[0060] Substituting the above four coefficients into formula (1), the mesh tension formula is obtained:

[0061] F=(―63.33679D+260.62564)Av (―0.07564D+1.7239) (1+(-1.33738D+29.70798)β (―0.262D+2.64244) )……(2)

[0062] The mesh tension formula can be used to calculate the mesh tension by taking the pore size, flow rate and blockage rate as variables.

[0063] like Figure 4 As shown, based on the comparison and verification between the fitting formula and the actual test data, it can be seen that the distribution pattern of the test points is good, and the fitting is good when the tension is less than 50N. Relevant calculations can be performed according to the formula.

[0064] For the mesh with 1 cm aperture, the calculated value of the formula fits the experimental data more accurately at low blockage rates (0-0.5), especially at flow rates of 0.1 m / s and 0.2 m / s, where the fitting line almost coincides with the experimental data points. When the blockage rate exceeds 0.5, although the calculated value is slightly higher than the experimental data, the overall trend remains consistent, indicating that the formula still has good fitting ability at high blockage rates. Under the condition of 2 cm aperture, the fitting accuracy performs well under flow rates of 0.1 m / s and 0.2 m / s, and the experimental data is highly consistent with the fitting curve. As the flow rate increases to 0.3 m / s, the gap between the fitting curve and the experimental data increases slightly, especially at high blockage rates (above 0.6), the experimental data is slightly lower than the fitting value, but the fitting line can better reflect the nonlinear trend of tension with increasing blockage rate. For the mesh with 3 cm aperture, the fitting results are consistent with the experimental data at low flow rates (0.1 m / s and 0.2 m / s), especially in the low blockage rate area. As the blockage rate increases, especially at a flow rate of 0.3 m / s, the test data points are slightly lower than the fitting curve, and the difference is more obvious at high blockage rates. However, the overall fitting trend remains consistent, reflecting the applicability of the model.

[0065] In summary, under low blockage rate (0-0.5) conditions, the fitting accuracy of all apertures and flow rates is high, and the calculated values ​​of the formula are basically consistent with the experimental data, indicating that the formula has a high prediction accuracy in this range. When the blockage rate exceeds 0.5, the calculated value of the formula is slightly higher than the experimental data, especially in the case of 0.3m / s flow rate and small aperture. This may be due to the complex flow phenomenon under high blockage rate, which has a greater dissipation effect on the tension in the test, resulting in the actual tension value being lower than the theoretical value.

[0066] The mesh tension formula captures the nonlinear growth trend of tension with blockage rate very well. Especially at high flow rates, the trends of the test data and the fitting curve are consistent, which verifies the validity of the formula.

[0067] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from them are still within the protection scope of the invention.

Claims

1. A mesh tensile test device, characterized in that: include: sink; A water pump, used to drive the water flow along the flume; The mesh is arranged on the cross section of the water tank, and comprises a mesh frame and a mesh body fixed on the mesh frame; A tension sensor is disposed upstream of the mesh and connected to the mesh via a pull rope; An installation base, used for installing the tension sensor; A plurality of wet viscose fiber towels are used to simulate jellyfish being blocked by a mesh; the specific strength of the wet viscose fiber towels is 8.0-13.5 N·m / g.

2. The mesh tensile testing device according to claim 1, characterized in that: The wet viscose fiber towel is circular and can be attached to the upstream side of the net body.

3. The mesh tensile testing device according to claim 1, characterized in that: There are multiple pull ropes, and the multiple pull ropes are connected to the net frame.

4. The mesh tensile testing device according to any one of claims 1 to 3, characterized in that: The installation base comprises a vertical pole which is vertically inserted downward into the water tank, a traction rope is arranged on the vertical pole, and the tension sensor is connected to the traction rope.

5. A mesh tensile test method, characterized in that: The method is realized by the mesh tensile test device according to any one of claims 1 to 4, comprising: The water in the water tank is driven to flow at a preset flow rate by a water pump; A number of wet viscose fiber towels are applied to the upstream side of the net body according to a preset blocking rate, wherein: The tension applied to the mesh is obtained through a tension sensor.

6. A mesh tension prediction method, characterized in that: The mesh tension is predicted by the following formula: F=(―63.33679D+260.62564)Av(―0.07564D+1.7239)(1+(―1.33738D+29.70798)β(―0.262D+2.64244)); Among them, F is the tension on the mesh, A is the mesh area, v is the flow velocity, β is the blockage rate; and D is the pore size of the mesh.

7. The mesh tension prediction method as claimed in claim 6, characterized in that: By using the mesh tensile test method as claimed in claim 5, multiple test data of the tensile force borne by the mesh under different mesh apertures, different flow rates and different blockage rates are obtained, and the following formula is obtained by fitting the data using a model based on the Morrison equation: F=k1Av n (1+k2β m ); The experimental data was formed into a matrix and brought into Matlab for least squares fitting to obtain the fitting formula coefficient table. According to the changes in aperture and coefficient, the relationship between coefficient and aperture was linearly fitted again to obtain the relationship between four coefficients and aperture: k1=-63.33679D+260.62564; k2=-1.33738D+29.70798; n=―0.07564D+1.7239; m=―0.262D+2.64244; Thus, the mesh tension formula is obtained.

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