CN112464589B - A Simplified Numerical Simulation Method for Aerodynamic Resistance of Transmission Conductors - Google Patents

Abstract

The invention discloses a simplified numerical simulation method for the aerodynamic resistance of a power transmission wire, which is carried out according to the following steps: determining N types of power transmission wires and corresponding parameters of the power transmission wire, and the test scene of the wind tunnel test; Carry out wind tunnel tests on the transmission wires to obtain the relationship between the aerodynamic drag coefficient of the transmission wires and the wind speed; select a wire as the target transmission wire, and simulate the geometric model of the target transmission wire; simplify the wire groove in the geometric model of the target transmission wire Get the geometric simplified model of the target transmission wire; preset the influence factor of the aerodynamic resistance coefficient, and use CFD software to numerically simulate the aerodynamic resistance coefficient of the transmission wire in the geometric simplified model of the target transmission wire, and obtain the relationship between the target transmission wire and the wind speed; lock the aerodynamic resistance coefficient impact factor. Beneficial effect: a wire simulation method is proposed, which greatly reduces calculation data and difficulty.

Description

A Simplified Numerical Simulation Method for Aerodynamic Resistance of Transmission Conductors

technical field

The invention relates to the technical field of power transmission wire simulation, in particular to a simplified numerical simulation method for the aerodynamic resistance of a power transmission wire.

Background technique

Wind load dominates all loads on transmission lines, and it has a significant impact on the strength design of the tower foundation and the tower itself. The calculation of the wind load of the transmission line in the project largely depends on the value of the resistance coefficient suggested in the corresponding design code. With the rapid construction of power grid scale and the continuous changes of climate and environment, the wind damage of conductors is becoming more and more serious. Therefore, it is very important to accurately calculate and reduce the resistance coefficient of the wire, especially in the windy environment. Only by improving the structural strength of transmission lines under strong wind conditions, a large amount of investment is required to achieve the purpose of wind resistance, and there are certain limitations. The traditional aluminum conductor steel reinforced (ACSR) is the most common wire, and its outer strand is usually circular in cross-section. On the basis of the structure of ACSR, the aerodynamic shape optimization and the development of special-shaped wires with a small resistance coefficient have broad application prospects.

According to previous studies, the resistance coefficient of a single conductor is mainly affected by factors such as Reynolds number, incoming wind direction, turbulence, and surface structure (roughness) of the conductor. For multi-split wires, it is also affected by the number, spacing, and angle of sub-wires. However, they are all researches on specific conductors, and there are few systematic analyzes on the influence of different surface structure forms (roughness) of conductors, which are far from meeting the needs of engineering applications.

A wire can be viewed as a rough cylinder with multiple helical strands or grooves on its surface. The flow around a rough cylinder is similar to that of a smooth cylinder (Achenbach, 1971; Achenbach and Heinecke, 1981; Farell and Arroyave, 1990): the drag coefficient is basically unchanged in the subcritical region and is not affected by roughness. The minimum drag coefficient in the critical area increases with the increase of relative roughness K/D. Roughness can lead to premature separation of the boundary layer, reducing the critical Reynolds number. The drag coefficient in the supercritical region increases with the increase of K/D. Helical wires or grooves have been extensively studied as an omnidirectional damping device (Law and Jaiman, 2018; Ishihara and Li, 2020). (Szalay, 1989; Tanaka et al., 2012; Tang et al., 2013; Kim et al., 2015) conducted experimental studies on the forces and responses of straight and spiral high-rise buildings with polygonal cross-sections, which can provide a basis for the research of new types of conductors. for reference.

Based on the above technology, in the calculation of the aerodynamic drag coefficient of the wire, there are still defects such as complex calculation data and a large amount of calculation, which lead to difficult calculations and greatly hinder the progress of the wire simulation technology.

Contents of the invention

In view of the above problems, the present invention provides a simplified numerical simulation method for the aerodynamic resistance of a power transmission wire. The wind tunnel test research is carried out on the wire, and the change rule of the drag coefficient with the wind speed is obtained. Then CFD simulation is used to simplify the traditional wire geometry model. A simpler wire simulation method is obtained, and the calculation amount is greatly reduced.

In order to achieve the above object, the concrete technical scheme that the present invention adopts is as follows:

A simplified numerical simulation method for the aerodynamic resistance of a transmission wire, the key steps of which are as follows:

S1: Determine N types of transmission wires and corresponding transmission wire parameters, and determine the test scenario of the wind tunnel test;

S2: Define the formula for the resistance coefficient of the transmission wire, conduct wind tunnel tests on N types of transmission wires, and obtain the relationship between the aerodynamic resistance coefficient of the transmission wire and the wind speed;

S3: Randomly select one of the N types of transmission conductors as the target transmission conductor, use CFD software to simulate the target transmission conductor, verify the accuracy of the simulation, and obtain the geometric model of the target transmission conductor;

S4: Simplify the conductor groove in the geometric model of the target transmission conductor to obtain a simplified geometric model of the target transmission conductor;

S5: According to the test scene of the wind tunnel test in step S1, the influence factor of the aerodynamic drag coefficient is preset, and CFD software is used to numerically simulate the aerodynamic drag coefficient of the transmission conductor of the geometrically simplified model of the target transmission conductor, and the effect of the influence factor of the aerodynamic drag coefficient is obtained Next, the relationship between the target transmission line and the wind speed; and lock the influence factor of the aerodynamic drag coefficient.

Through the above-mentioned scheme, the wind tunnel test was carried out on all the conductors firstly, and the change law of the drag coefficient with the wind speed was obtained. Then CFD simulation is used to simplify the traditional wire geometry model. One of the new wires was selected, and the influence of its groove depth and number of grooves on the drag coefficient was studied. A wire simulation method is proposed, which greatly reduces the calculation data and difficulty.

In a further calculation scheme, the parameters of the transmission wire at least include the cross-sectional area of the wire, the number of outer strands, the diameter of the outer strands, the shape of the outer strands, and the outer diameter of the conductor; in the test scene of the wind tunnel test, at least The test parameters included are: the length of the conductor test section, the space size of the return wind tunnel, the wind speed threshold of the wind tunnel, the degree of turbulence, the value of wind speed non-uniformity, the sampling frequency of the aerodynamic drag coefficient of the transmission conductor, and the sampling time of the aerodynamic drag coefficient of the transmission conductor.

In a further calculation scheme, the formula for the resistance coefficient of the transmission wire is:

Among them, C _D is the drag coefficient of the wire; F _D is the average value of the measured resistance applied to the wire; ρ is the air density; U is the wind speed perpendicular to the wire; L is the length of the wire; D is the outer diameter of the wire.

In a further calculation scheme, the geometric simplified model of the target transmission wire adopts a shear stress transfer model; the model calculation domain is: taking the center of the wire as the coordinate origin, its width and depth are respectively 30D and 40D; the calculation domain spanwise length 5D, each twisted wire is rotated 180° along the spanwise length L=5D, and a centrosymmetric and periodic model is established, D is the outer diameter of the wire; the model network is: the wire groove adopts a wedge-shaped grid; the twisted wire The wall adopts a hexahedral grid, and the twisted wires away from the wall adopt a wedge-shaped grid; the internal grid of the wire flow field is a helical twisted wire grid formed by sweeping the two-dimensional grid along the span direction and distorting the grid at the same time; The outside of the field is directly swept along the span direction, and the inner grid of the wire flow field is connected with the outer grid of the wire flow field through a non-matching grid.

In a further calculation scheme, in step S4, the content of simplifying the conductor groove in the geometric model of the target power transmission conductor is:

The geometric model of the target transmission wire is equivalently replaced by the equivalent surface roughness of the wire in the range of the test wind speed, and the geometric simplified model of the target transmission wire is obtained; the calculation formula of the equivalent roughness of the wire surface is:

Where R(θ,z,t) is the local radius, which represents the distance from the center C of the section to a point on the surface, which is a function of the angle θ on the cylinder, the position z along the axis of the cylinder, and time t;

D is the outer diameter of the wire; R is the radius of the circumscribed circle of the wire, D=2R;

If err(θ,z,t) is equal to 0 at every point, then the cylinder is circular and has a constant cross-section.

In a further calculation solution, in step S5, the preset aerodynamic resistance coefficient influencing factor includes at least the depth of the wire groove and the number of wire grooves; the aerodynamic resistance coefficient influencing factor is the depth of the wire groove.

Beneficial effects of the present invention: the depth that can reasonably simulate the prototype is found, and the influence factor of the aerodynamic resistance coefficient is the depth of the conductor groove. Through simulation, it is found that the resistance coefficient first decreases with the depth of the groove, then increases and then stabilizes. The wire shape with the best effect of reducing the drag coefficient is obtained.

Description of drawings

Figure 1 is a schematic diagram of the wire model

Figure 2 is a schematic diagram of the cross-sectional shape of the traditional wire (top) and its corresponding new wire (bottom)

Figure 3 is the installation layout of the wind tunnel test model

Figure 4 is a schematic diagram of the comparison of drag coefficient C _D and drag reduction rate with wind speed;

Fig. 5 is a schematic diagram of the computational domain of the wire;

Fig. 6 is a schematic diagram of a traditional wire grid;

Fig. 7 is a schematic diagram of groove depth;

Fig. 8 is a schematic diagram of the traditional wire drag coefficient changing curve with wind speed;

Fig. 9 is a schematic diagram of the comparison between the drag coefficient test value and the simulated value;

Figure 10 is a schematic diagram of the variation of the drag coefficient with the depth of the groove;

Figure 11 is a schematic diagram of the average streamline diagram;

Figure 12 is a schematic diagram of the boundary layer profile;

Fig. 13 is a flowchart of the method of the present invention.

Detailed ways

The specific implementation manner and working principle of the present invention will be further described in detail below in conjunction with the accompanying drawings.

A simplified numerical simulation method for the aerodynamic resistance of a power transmission conductor is carried out according to the following steps:

S1: Determine N types of transmission wires and corresponding transmission wire parameters, and determine the test scenario of the wind tunnel test;

The parameters of the power transmission wire at least include the cross-sectional area of the wire, the number of outer layer strands, the diameter of the outer layer strands, the shape of the outer layer strands, and the outer diameter of the wire;

The test parameters at least included in the test scene of the wind tunnel test are: the length of the wire test section, the space size of the return wind tunnel, the wind speed threshold of the wind tunnel, the degree of turbulence, the value of wind speed non-uniformity, the sampling frequency of the aerodynamic drag coefficient of the transmission wire, and the power transmission line. Traverse aerodynamic drag coefficient sampling time.

In this embodiment, N=3, and the three types of power transmission wires are: JL/G1A-630/45, JL/G2A-720/50 and JL1/G2A-1250/100.

In Table 1, the section parameters of the six actual wires corresponding to the wires in 3 are listed. In the test, the geometric scale ratio of 1:1 was used to make the rigid model of the wire. The model wire is made by covering the 3D printed wire shell on the duralumin tube. The shell is made of PLA plastic, which is accurately printed and fits tightly with the duralumin tube, which ensures the rigidity of the model. The pitch-to-diameter ratio of all wires is around 11, spiraling counterclockwise.

Among them, the groove depth h of JLX2/G1A(DFY)-720/50 is the distance between the bottom of the groove and the circumscribed circle of the wire. The effective length of the model wire is 1.7m. See Figure 1 and Figure 2 for the wire model and cross-sectional shape.

Table 1 Parameters of traditional conductors and their corresponding low wind pressure conductors

The test scenarios of the wind tunnel test are:

The wind tunnel test is carried out in the high-speed test section of the wind tunnel laboratory of Shijiazhuang Railway University, which is a closed backflow wind tunnel. The test section is 5m long, 2.2m wide, and 2m long, with a maximum wind speed of 80m/s. At 63m/s, the degree of turbulence is less than 3%, and the unevenness of wind speed is less than 1%.

To simulate actual wires, end plates were installed at both ends of the model. The end plates are installed on the sleeves at both ends and fixed on the wind tunnel wall through external supports, so that the end plates and the wires are separately stressed. The end plates are 8mm thick and 260mm in diameter and are made of hardwood planks, which is thick enough to provide out-of-plane stiffness. In order to minimize the cross-wind vibration of the end plate and the influence on the flow field, the edge is inclined at 45°. A six-component high-frequency force balance (HFFB) was installed horizontally at both ends of the aluminum tube, with a sampling frequency of 1500 Hz and a sampling time of 20 s. See Figure 3, which shows the final test setup in the wind tunnel.

S2: Define the formula of the resistance coefficient of the transmission wire, conduct wind tunnel tests on three kinds of transmission wires, and obtain the relationship between the aerodynamic resistance coefficient of the transmission wire and the wind speed;

The formula for the resistance coefficient of the transmission wire is:

Among them, C _D is the drag coefficient of the wire; F _D is the average value of the measured resistance applied to the wire; ρ is the air density; U is the wind speed perpendicular to the wire; L is the length of the wire; D is the outer diameter of the wire.

In this embodiment, seven uniform wind speeds are considered, and the wind speed ranges from 10.0 m/s to 44.8 m/s.

Combining with Figure 4, it can be seen that the test measured the resistance of three groups of traditional conductors and their corresponding new conductors in the wind speed range of 10m/s-44.8m/s, and obtained the change law of _CD and drag reduction rate with wind speed. Drag reduction rate = (new wire resistance coefficient - traditional wire resistance coefficient) / traditional wire resistance coefficient.

The C _D -U curves of the three traditional conductors and their corresponding new conductors all decrease first, then rise, and finally tend to be stable, which is consistent with the previous test results. The wind speed corresponding to the minimum value of C _D of the traditional wire is between 15m/s and 20m/s, and the wind speed value corresponding to the minimum point of the resistance coefficient of the new wire is greater than 25m/s. The drag reduction ratios of the three new types of conductors also have a law of first decreasing and then increasing until they are stable. When the wind speed is low, the drag reduction rates of the three new conductors are very small, even less than 0, and the drag reduction effect cannot be achieved. When the wind speed is greater than 15m/s, the drag reduction rate gradually increases; when it exceeds 25m/s, it is always positive, and there is an obvious drag reduction effect. Among the three new types of wires, the drag coefficient reduction effect of (e) wire is more obvious, and the maximum drag reduction rate is 36.98%.

S3: Randomly select one of the three types of transmission wires as the target transmission wire, use CFD software to simulate the target transmission wire, verify the accuracy of the simulation, and obtain the geometric model of the target transmission wire;

In this embodiment, the wire JLX2/G1A(DFY)-720/50 is selected.

The geometrically simplified model of the target transmission line uses a shear stress transfer model; this model involves two transport equations, namely one for turbulent kinetic energy and a specific dissipation rate. The Unsteady Separation Algorithm (USA) was used in the analysis. The coupled velocity expressions are handled with the SIMPLE algorithm, and a second-order implicit scheme is used for unstable cases. A second-order scheme is used for the k-ω transport equation and the convective term in the momentum equation.

Combining with Figure 5, it can be seen that the calculation domain of the model is: taking the center of the wire as the coordinate origin, its width and depth are 30D and 40D respectively; the span length of the calculation domain is 5D, and each twisted wire rotates along the span length L=5D 180°, a centrally symmetrical and periodic model is established, D is the outer diameter of the wire;

The aerodynamic forces of long cylinders can be effectively predicted by using symmetric boundary conditions at both ends of the cylinder during simulation. The cylinder is located 15D downstream of the inlet. The uniform velocity condition is adopted at the entrance boundary, U=19.5m/s, and the Reynolds number based on the outer diameter of the wire is Re=UD/ν≈4.8×10 ⁴ . A pressure outlet condition is used at the outlet boundary. Symmetrical boundary conditions are applied to the top, bottom and lateral surfaces of the computational domain.

The traditional flow field network includes local grid, wall local grid, and steel strand wall local elevation grid. See Figure 6 for details. Due to the small depth of the grooves between the strands, high resolution is required to accurately capture the flow field properties.

In this embodiment, the model network is: the conductor groove adopts a wedge-shaped grid; so as to ensure the accuracy of the complex geometric shape of the twisted wire.

The hexahedral grid is used on the wall of the stranded wire to form a boundary layer grid;

Wedge grids are used for the strands away from the wall; to avoid grids with excessive slenderness.

The entire flow field uses a hybrid grid system and divides it into inner and outer areas. The internal grid of the wire flow field is a spiral strand grid formed by sweeping the two-dimensional grid along the span direction and distorting the grid at the same time; the outside of the wire flow field is directly swept along the span direction, and the internal grid of the wire flow field Connect to the external mesh of the wire flow field through a non-matching mesh.

The mesh size is similar on both sides of the interface so accuracy is maintained. This grid system not only helps to generate a reasonable grid, but also allows to speed up calculations with sufficient precision using a smaller number of grids. The same meshing strategy is used for the new type of wires.

The convergence of the mesh is verified by several dimensionless aerodynamic parameters of the wire, namely the root mean square of the drag and lift coefficients and the Strouhal number. The Strouhal number is denoted by S _t =f _v D/U, where f _v represents the vortex shedding frequency obtained by spectral analysis of the lift force on the cylinder. Table 2 shows the average drag coefficient C _D , the root mean square lift coefficient C _Lrms and S _t of grids with different resolutions. Grid resolution increases gradually from grid 1 to grid 3. The results between grid 2 and grid 3 are less than 2%, and both are less than 2% compared with the test results, which is acceptable for engineering application convergence. Therefore, grid 2 is used in the following simulations considering accuracy and efficiency.

Table 2 Grid independence verification

grid Number of grids C_D C_Lrms S_t Grid 1 2,845,040 1.028 0.70 0.23 Grid 2 4,192,560 0.945 0.51 0.22 Grid 3 5,746,800 0.934 0.49 0.23 test value 0.929 0.47 0.22

S4: Simplify the conductor groove in the geometric model of the target transmission conductor to obtain a simplified geometric model of the target transmission conductor;

It can be seen from the grids near the wall of the stranded wire in Figure 6(b) that if the traditional wire flow field is directly divided into grids, the number of grids will be particularly large. Especially in the grooves between the twisted wires, the grids are not only numerous but also small, which will lead to convergence difficulties during calculation and may not necessarily lead to correct results. According to the basic assumption of viscous fluid, the fluid near the included angle is very close to each wall, so the fluidity is poor, the flow resistance is large, and the velocity is almost zero. And according to the previous reduction of the sharp angle of the groove of the traditional wire, the relative roughness of the wire surface does not change much, so the influence on the CD is small.

Therefore, the groove of the traditional wire JLX2/G1A(DFY)-720/50 in Figure 2(b) is simplified to find a depth that can reasonably simulate the prototype wire.

Since the wire resistance coefficient is related to multiple parameters such as the outer strand diameter, quantity and wire diameter,

Then in step S4, the content of simplifying the wire groove in the geometric model of the target power transmission wire is:

The geometric model of the target transmission wire is equivalently replaced by the equivalent roughness of the surface of the wire in the range of the test wind speed, and the geometric simplified model of the target transmission wire is obtained;

The formula for calculating the equivalent roughness of the wire surface is:

Where R(θ,z,t) is the local radius, which represents the distance from the center C of the section to a point on the surface, which is a function of the angle θ on the cylinder, the position z along the axis of the cylinder, and time t;

D is the outer diameter of the wire; R is the radius of the circumscribed circle of the wire, D=2R;

If err(θ,z,t) is equal to 0 at every point, then the cylinder is circular and has a constant cross-section.

S5: According to the test scene of the wind tunnel test in step S1, the influence factor of the aerodynamic drag coefficient is preset, and CFD software is used to numerically simulate the aerodynamic drag coefficient of the transmission conductor of the geometrically simplified model of the target transmission conductor, and the effect of the influence factor of the aerodynamic drag coefficient is obtained Next, the relationship between the target transmission line and the wind speed; and lock the influence factor of the aerodynamic drag coefficient.

In step S5, the preset aerodynamic drag coefficient influencing factor includes at least the wire groove depth and the number of wire grooves; the locked aerodynamic drag coefficient influencing factor is the wire groove depth.

It can be seen from Figure 7 that concentric circles with different diameters are used to reduce the depth of the groove, and the depth of the groove is reduced. The roughness and corresponding C _D are shown in Table 3.

Table 3 C _D at different groove depths of steel strands

serial number Groove depth h(mm) Equivalent roughness K_e/D(%) C_D C_Lrms S_t experiment 2.525 1.533 0.929 0.47 0.22 Simulation 1 2.115 1.527 0.945 0.51 0.22 Simulation 2 1.715 1.492 0.945 0.51 0.22 Simulation 3 1.315 1.395 0.947 0.52 0.22 Simulation 4 0.915 1.198 0.936 0.47 0.22 Simulation 5 0.715 1.047 0.990 0.57 0.22 Simulation 6 0.515 0.850 1.098 0.80 0.24

The width of the deep groove of the traditional wire is small, and the width of the shallow part is deep, so the initial reduction of the groove depth has little effect on the equivalent roughness. When the equivalent roughness is 1.198%, the resistance coefficient of the simplified wire is very close to that of the original wire. When the equivalent roughness is further reduced, the results vary greatly. The change law of drag coefficient with the groove depth will be analyzed in detail in the following research on the new wire groove. Using this equivalent roughness, the CFD simulation of the traditional wire was carried out in the test wind speed range. The simulated value of the drag coefficient is very close to the experimental value in this paper, see Figure 8 for details.

Select the new wire JLX1/G1A(DFY)-680/45 in Figure 2(e) to further study its aerodynamic force. It can be seen from the test results that the wire can more effectively reduce the resistance coefficient of the wire. Firstly, CFD simulation was carried out within the test wind speed range. The change law of drag coefficient with wind speed is shown in 9. The simulation results are basically consistent with the test results, and the simulation accuracy meets the requirements. Changing the groove depth and the number of grooves of the new conductor, the simulation analysis was carried out at the wind speed U=30m/s, Re≈7.1×10 ⁴ .

Referring to Fig. 10, it is the variation curve of the wire resistance coefficient with the groove depth, wherein the groove depth of 0.29mm is the original depth of the new wire. It can be seen that the resistance coefficient of the new conductor increases with the depth of the groove, and when the depth of the groove is 0.5mm, it even exceeds that of the traditional conductor corresponding to the low wind pressure conductor.

See Figure 11 for the average streamline plots of a smooth cylinder and wires with three different groove depths.

Shown in Fig. 11 is the average flow velocity of the mid-span section of the wire. The enlarged image on the right is the separation position of the boundary layer (red box area). The wake is mainly composed of a pair of symmetrical vortex rings, and their length is usually called the recirculation length. The surface roughness of the cylinder will significantly affect the shape of the wake, and the wake recirculation length of the wire is significantly longer than that of a smooth cylinder. Figure 11(d) shows that there are small eddies in the groove, which are caused by the local separation of the fluid in the groove. The separation point can be found by drawing a section of the boundary layer. Figure 12 is the outline of the boundary layer near the separation point of the mid-span section of wires with different groove depths. It can be seen that the boundary layer profile changes from an L-shape to an S-shape, indicating the presence of an inflection point, the separation point. See Table 4 for the exact separation point position θ _s and the recirculation length L _r /D. The separation point of a smooth cylinder is 88.6°, and a shallow groove will move the separation point backward, resulting in a decrease in the drag coefficient, but when the groove is deep enough, the separation will occur at the edge of the groove, and the drag coefficient will increase instead .

Table 4 Wire recirculation length and separation point position for different groove depths

The number of grooves has little effect on the drag coefficient of the wire, with only a slight decreasing trend. When the number of sides is large, the influence of changing the number of sides is small, which can be confirmed from the experiment of regular polygons. The more sides, the closer to a smooth cylinder, so the drag coefficient is reduced.

From the above analysis, it can be seen that the polygon is the most effective in reducing the drag coefficient. Therefore, changing the number of sides, carried out CFD simulation on the regular 16, 18, and 20 polygons. As the number of sides increases, the drag coefficient becomes smaller. See Table 5 for details.

Table 5 Resistance coefficients of wires with different numbers of sides

Number of sides 16 18 20 C_D 0.765 0.720 0.690

The three low-wind-pressure conductors can all reduce the drag coefficient when the wind speed is greater than 25m/s, but the effect is not obvious when the wind speed is low, and the drag coefficient even increases.

The simplification of traditional power transmission wires shows that when the equivalent roughness Ke/D>1.198%s, the depth of the groove is too narrow and has little effect on the flow field. Simplifying the geometric model of traditional transmission lines can greatly reduce the difficulty of grid division and the number of grids, so that CFD simulation analysis can be performed more accurately.

The drag coefficient decreases firstly with the depth of the groove, then increases and then stabilizes.

It should be noted that the above description is not intended to limit the present invention, and the present invention is not limited to the above-mentioned examples. Those skilled in the art may make changes, modifications, additions or replacements within the scope of the present invention. It should also belong to the protection scope of the present invention.

Claims (5)

1. A simplified numerical simulation method for the aerodynamic resistance of a power transmission wire is characterized in that it is carried out according to the following steps: S1: Determine N types of transmission wires and corresponding transmission wire parameters, and determine the test scenario of the wind tunnel test; S2: Define the formula for the resistance coefficient of the transmission wire, conduct wind tunnel tests on N types of transmission wires, and obtain the relationship between the aerodynamic resistance coefficient of the transmission wire and the wind speed; S3: Randomly select one of the N types of transmission conductors as the target transmission conductor, use CFD software to simulate the target transmission conductor, verify the accuracy of the simulation, and obtain the geometric model of the target transmission conductor; S4: Simplify the conductor groove in the geometric model of the target transmission conductor to obtain a simplified geometric model of the target transmission conductor; The simplified content of the conductor groove in the geometric model of the target transmission conductor is: The geometric model of the target transmission wire is equivalently replaced by the equivalent roughness of the surface of the wire in the range of the test wind speed, and the geometric simplified model of the target transmission wire is obtained; The formula for calculating the equivalent roughness of the wire surface is:

Where R(θ,z,t) is the local radius, which represents the distance from the center C of the section to a point on the surface, which is a function of the angle θ on the cylinder, the position z along the axis of the cylinder, and time t; D is the outer diameter of the wire; R is the radius of the circumscribed circle of the wire, D=2R; If err(θ,z,t) is equal to 0 at every point, the cylinder is circular and has a constant cross-section; S5: According to the test scene of the wind tunnel test in step S1, the influence factor of the aerodynamic drag coefficient is preset, and CFD software is used to numerically simulate the aerodynamic drag coefficient of the transmission conductor of the geometrically simplified model of the target transmission conductor, and the effect of the influence factor of the aerodynamic drag coefficient is obtained Next, the relationship between the target transmission line and the wind speed; and lock the influence factor of the aerodynamic drag coefficient. 2. The simplified numerical simulation method for the aerodynamic resistance of a power transmission wire according to claim 1, wherein the parameters of the power transmission wire at least include the cross-sectional area of the wire, the number of outer strands, the diameter of the outer strands, and the diameter of the outer strands. Shape, wire outer diameter; The test parameters at least included in the test scene of the wind tunnel test are: the length of the wire test section, the space size of the return wind tunnel, the wind speed threshold of the wind tunnel, the degree of turbulence, the value of wind speed non-uniformity, the sampling frequency of the aerodynamic drag coefficient of the transmission wire, and the power transmission line. Traverse aerodynamic drag coefficient sampling time. 3. The simplified numerical simulation method for the aerodynamic resistance of the transmission wire according to claim 2, wherein the formula for the resistance coefficient of the transmission wire is:

Among them, C _D is the drag coefficient of the wire; F _D is the average value of the measured resistance applied to the wire; ρ is the air density; U is the wind speed perpendicular to the wire; L is the length of the wire; D is the outer diameter of the wire. 4. The simplified numerical simulation method for the aerodynamic resistance of the transmission wire according to claim 1, characterized in that: the simplified geometry model of the target transmission wire adopts a shear stress transfer model; The calculation domain of the model is: taking the center of the conductor as the coordinate origin, its width and depth are 30D and 40D respectively; the calculation domain spanwise length is 5D, and each twisted wire is rotated 180° along the spanwise length L=5D to establish a center Symmetrical and periodic model, D is the outer diameter of the wire; The model network is as follows: the wire groove adopts wedge-shaped grid; the wall of the twisted wire adopts hexahedral grid, and the twisted wire away from the wall adopts wedge-shaped grid; The spiral wire grid is formed by using the grid; the outside of the wire flow field is directly swept along the span direction, and the inner grid of the wire flow field is connected with the outer grid of the wire flow field through a non-matching grid. 5. The simplified numerical simulation method for aerodynamic resistance of power transmission wire according to claim 1, characterized in that: in step S5, the preset aerodynamic resistance coefficient influencing factors include at least the depth of the wire groove and the number of wire grooves; the locked aerodynamic resistance The coefficient influencing factor is the wire groove depth.

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