Air blowing optical cable convex part design method based on air pushing compensation and air blowing optical cable

Abstract

The application provides a convex part design method of air-blow optical cable based on air-push compensation and the air-blow optical cable. The optical cable comprises a round cable body, a plurality of convex parts are uniformly distributed on the cable body, a concave part is formed between two adjacent convex parts, the profile of the convex part is half of an ellipse, and two end points of the half of the ellipse in the tangent direction of the cable body are located on a dedendum circle. The convex part design method comprises the following steps: introducing an air-blow compensation coefficient of the optical cable, the lower limit of the air-blow compensation coefficient is close to the minimum value of the ratio of the unit length friction of the optical cable to the unit length thrust of the gas, and the upper limit of the air-blow compensation coefficient is the maximum value of the ratio of the arc length of the convex part to the arc length of the overlapping part of the convex part and the dedendum circle; taking a constant in the range of the air-blow compensation coefficient to calculate the minimum number of the convex parts; substituting the minimum number into a calculation formula of the number of the convex parts to obtain a relational expression of the half first axis length and the half second axis length, and selecting the value based on the value range, the step, the relational expression and the requirement of the half first axis length and the half second axis length.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cable blowing, in particular to a convex part design method of cable blowing based on air pushing compensation and cable blowing. BACKGROUND

[0002] In the cable blowing technology, the optical cable is sent into the pipeline by high-pressure gas flow. During the cable blowing process, the optical cable is subjected to gas thrust and friction. The core mechanical equilibrium condition of this process is that the gas thrust is greater than or equal to the friction. If the gas thrust is insufficient, the optical cable may be stuck, the laying efficiency may be reduced, and even the optical cable outer sheath may be damaged.

[0003] In the design of optical cable, for optical cable with large mass or long distance laying, the traditional method relies on adding convex parts (such as spiral ribs, corrugated structures, discrete convex points, etc.) on the outer surface of the optical cable to compensate for the insufficient gas thrust. However, in the actual design process, the following problems exist: the calculation process is complex, there is a lack of universal model, the design process relies on numerical simulation (such as CFD) or a large number of experiments, and the efficiency is low; the thrust compensation lacks quantitative basis, the optimization of convex part structure is usually based on empirical formula or historical cases, there is a lack of unified design standard, and experience design is mainly relied on; in long distance laying, the cumulative error may cause the thrust compensation to fail, affecting the construction efficiency. It can be seen that the existing thrust compensation technology of cable blowing is still in the semi-empirical stage, and a systematic design theory and standardized method are needed to improve the reliability and economy of large mass optical cable laying. SUMMARY

[0004] The purpose of the present application is to provide a convex part design method of cable blowing based on air pushing compensation and cable blowing to solve the above problems.

[0005] The technical solution adopted by the present application is as follows:

[0006] A convex part design method of cable blowing based on air pushing compensation, the optical cable includes a circular cable body, a plurality of convex parts are uniformly distributed on the cable body in the circumferential direction, a concave part is formed between two adjacent convex parts, the circle where the cable body is located is the dedendum circle, the circle formed by the end part of the convex part away from the cable body is the addendum circle, the profile of the convex part is half an ellipse, and the two endpoints of the half ellipse in the tangent direction of the cable body are located on the dedendum circle, and the design steps are as follows:

[0007] S1. Introducing the cable blowing compensation coefficient α 缆 , ,

[0008] … (I);

[0009] F 摩 is the unit length friction force of the optical cable, F气推 is the unit length thrust of the gas;

[0010] … (II) ;

[0011] 凸 is the arc length of a convex part, 重合 is the arc length of a convex part coinciding with the dedendum circle;

[0012] … (III) ;

[0013] e is the eccentricity of a half-ellipse, E(e) is a complete second kind elliptic integral, H is the length of the longest axis of a half-ellipse in the radial direction of the optical cable, 0.2mm≤H≤0.4mm, W is half the length of the two endpoints of a half-ellipse in the tangent direction of the cable body, 0.15mm≤W≤0.4mm;

[0014] … (IV) ;

[0015] R 齿根 is the dedendum circle radius;

[0016] Substitute formula (III) and (IV) into formula (II) to establish a mathematical model of H, W and α2; set the step size △H=0.01mm, △W=0.01mm, traverse the values of H and W and substitute them into the above mathematical model, and take the maximum value of the calculation result as α2;

[0017] S2. Calculate the minimum number N of convex parts min + ;

[0018] The number of convex parts … (V) ;

[0019] α0 is a constant taken between (α1, α2], 缆min is the minimum wet perimeter length of the optical cable; according to the step size △H and △W, traverse the values of H and W and substitute them into formula (V), and take the minimum value N min to the nearest integer to obtain N min + ;

[0020] S3. Substitute N min + into formula (V) to obtain the relationship f(H, W) between H and W, and select the values of H and W based on the value range of H and W, the step size, f(H, W) and the requirements.

[0021] As a further improved technical solution of the present application, … (Six),

[0022] wherein, 缆 is the wet perimeter length of the optical cable.

[0023] As a further improved technical solution of the present application, α 缆max = 3.

[0024] As a further improved technical solution of the present application, … (Ten),

[0025] wherein, λ is the resistance coefficient along the path, ρ 气 is the density of the gas in the pipeline, v 气 is the velocity of the gas flow, and dl is the unit length.

[0026] As a further improved technical solution of the present application, ,

[0027] wherein, Re is the Reynolds number,

[0028] ,

[0029] wherein, μ 气 is the dynamic viscosity of the gas,

[0030] ,

[0031] wherein, ε is the absolute roughness of the inner wall of the pipeline.

[0032] As a further improved technical solution of the present application, … (Eleven),

[0033] wherein, G is the weight of the optical cable, g is the acceleration of gravity, g = 9.8 m / s 2 , and μ is the friction coefficient.

[0034] As a further improved technical solution of the present application, … (Seven).

[0035] A blown optical cable, the convex part of which can be designed according to the convex part design method of the blown optical cable based on air thrust compensation as described above.

[0036] As a further improved technical solution of the present application, the sum S 凹 of the areas of all the concave parts of the optical cable is:

[0037] … (Nineteen),

[0038] wherein, R 齿尖 is the radius of the tooth tip circle.

[0039] As a further improved technical solution of the present application, 5.2673mm 2 ≤S 凹 ≤6.9523mm 2 .

[0040] The present application has the beneficial effects of:

[0041] Through the above technical solution, based on the theory of mechanics and fluid dynamics, a universal thrust compensation model is established, and the compensation coefficient a 缆 is predicted through the critical thrust threshold 缆 Directly relate the optical cable parameters and the convex structure parameters, quantify the thrust compensation relationship, provide a standardized design method, reduce the cost of artificial trial and error, simplify the calculation process, avoid the construction interruption caused by insufficient thrust, and improve the design efficiency and laying success rate. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic diagram of the force of the optical cable in the pipeline when the cable is sent;

[0043] Figure 2 is a radial sectional view of the optical cable;

[0044] Figure 3 is a structure diagram of the convex part.

[0045] Among them: 1-optical cable, 2-convex part, 3-concave part, 4-gas, 5-pipeline. DETAILED DESCRIPTION

[0046] The present application will be described in detail below in conjunction with the specific embodiments shown in the drawings. However, these embodiments do not limit the present application, and the changes in structure, method, or function made by those of ordinary skill in the art based on these embodiments are all within the scope of protection of the present application.

[0047] If the present application involves orientation (for example, up, down, left, right, front, back, outside, inside, etc.) when it is described, the orientation involved needs to be defined, for example, "for the purpose of clearly expressing the position and direction described in the present application, the operator of the instrument is taken as a reference, the end close to the operator is the proximal end, and the end away from the operator is the distal end." Or define it with paper as a reference. Of course, if in the subsequent description, the positional relationship between the two is defined by mutual reference, it can not be defined here.

[0048] A gas-blowing optical cable, such as Figures 2-3As shown, the optical cable 1 is an approximately circular optical cable 1, the optical cable 1 includes a cable body with a circular cross section, a plurality of arc-shaped protrusions 2 are uniformly distributed on the cable body in the circumferential direction, a concave part 3 is formed between two adjacent protrusions 2, the circle defined by the cable body is defined as the root circle, and the circle formed by the collection of the end of the protrusion 2 away from the center of the optical cable 1 is defined as the tip circle, the profile of the protrusion 2 is half an ellipse, and the half ellipse partially overlaps the root circle, that is, the profile of the protrusion 2 is half an ellipse, the half ellipse is symmetrical in the radial direction of the root circle, and the two end points of the half ellipse farthest from the axis of symmetry are located on the root circle.

[0049] Based on the above air blowing optical cable, the present application provides a design method for the protrusion of the air blowing optical cable based on air pushing compensation, which comprises the following steps:

[0050] S1. Introducing an air blowing compensation coefficient α of the optical cable 1 缆 , and calculating the value range of the air blowing compensation coefficient α 缆 :

[0051] ;

[0052] The air blowing compensation coefficient α 缆 refers to, when the size and mass of the optical cable 1 are large, and no structure is arranged on the optical cable 1 to help improve the air pushing force, the air pushing force is smaller than the frictional force and cannot realize cable feeding, therefore, compensation needs to be given to the air pushing force to meet the condition that the air pushing force is greater than or equal to the frictional force for cable feeding, and this compensation is represented by the air blowing compensation coefficient α 缆 . Therefore, the limit minimum value of the air blowing compensation coefficient α 缆 is the ratio of the frictional force to the air pushing force when no structure is arranged on the optical cable 1 to help improve the air pushing force.

[0053] Therefore, ……(I);

[0054] Wherein, F 摩 is the unit length frictional force of the optical cable 1, and F 气推 is the unit length pushing force of the gas 4;

[0055] In the foregoing, the compensation mode for the air pushing force is set as the protrusion 2 arranged on the outer circumference of the optical cable 1, and the air blowing compensation coefficient α 缆 is reflected in the size and number of the protrusion 2, therefore, the air blowing compensation coefficient α 缆 is also limited by the tight limit of the arrangement of the protrusion 2 on the outer circumference of the optical cable 1.

[0056] Therefore, ……(II);

[0057] wherein, 凸 is an arc length of a half-ellipse corresponding to one convex part 2, 重合 is an arc length of a part where one convex part 2 coincides with a dedendum circle;

[0058] 凸 The calculation method is:

[0059] … (Three);

[0060] wherein, ;

[0061] ;

[0062] wherein, e is a eccentricity of a half-ellipse where the convex part 2 is located, E(e) is a complete second kind elliptic integral, H is a half-first axis length of the half-ellipse where the convex part 2 is located, the half-first axis is the longest axis of the half-ellipse in the radial direction of the optical cable 1, 0.2mm≤H≤0.4mm, W is a half-second axis length of the half-ellipse where the convex part 2 is located, 0.15mm≤W≤0.4mm, the second axis is half of the longest axis perpendicular to the half-first axis in the half-ellipse, that is, half of the length of the two end points of the half-ellipse in the tangent direction of the cable body;

[0063] 重合 The calculation method is:

[0064] … (Four);

[0065] wherein, R 齿根 is the radius of the dedendum circle;

[0066] The formula (Three) and the formula (Four) are substituted into the formula (Two) to establish a mathematical model of H, W and a2;

[0067] The step size AH=0.01mm and AW=0.01mm are set, and a plurality of calculation results of the mathematical model are obtained by traversing the values of H and W and substituting them into the above mathematical model, and the maximum value of the calculation results is taken as a2.

[0068] The step size is 0.01mm here, because if the step size is too large, it will affect the final forming precision of the product, and may cause assembly failure or functional defects; and the step size of 0.01mm sets a buffer margin for uncertain factors in the production process, ensuring the size consistency in batch production; if the step size is too small, the existing processing equipment cannot meet the processing requirements, which will lead to a decrease in processing stability.

[0069] S2. Calculate the minimum number N of convex parts 2 min + ;

[0070] With each increase in the number of convex parts 2 on the circumference of the optical cable 1, the wet perimeter length of the optical cable 1 increases by Δ , and Δ = 凸 - 重合 Therefore, the calculation formula of the number N of convex parts 2 is:

[0071] ……(V);

[0072] Wherein, α0 is a constant between (α1, α2], and 缆min is the minimum wet perimeter length of the optical cable 1;

[0073] According to the step size ΔH and ΔW, a plurality of calculation results of formula (V) are obtained by traversing the values of H and W and substituting them into formula (V). The minimum value N min of the calculation results is rounded up to be the minimum number N of convex parts 2 min + ;

[0074] When the number of convex parts 2 takes the minimum value, the basic driving force requirement of the blowing process can be met. From the mechanical properties, although the increase in the number of convex parts 2 can improve the blowing force received by the optical cable 1, it will also increase the dynamic load of the sheath of the optical cable 1. This is because the increase in the number of convex parts 2 will cause the volume proportion of a single convex part 2 to decrease relatively, and under the condition that the material distribution density is unchanged, the overall strength of the structure of the convex part 2 will show a trend of attenuation. In order to cope with uncertain factors in complex construction environment (such as pipe corner friction, air pressure fluctuation, etc.), as few convex parts 2 as possible should be used under the premise of meeting the blowing condition, and the number of convex parts 2 should be increased gradually only in the case of insufficient measured blowing force.

[0075] S3. Obtain the relationship between the half first axis length H and the half second axis length W;

[0076] Substitute the minimum number N of convex parts 2 min + into formula (V) to obtain the relationship f(H, W) between the half first axis length H and the half second axis length W. Based on the value range of the half first axis length H, the value range of the half second axis length W, the step size (ΔH and ΔW), f(H, W) and the use requirement, the values of the half first axis length H and the half second axis length W are selected.

[0077] At this point, through the above steps, α 缆Given a range of values α0, get the minimum number N of convex parts 2 min + , and the relationship between the half first axis length H and the half second axis length W under the condition of N min + and α0f(H, W), since the half first axis length H and the half second axis length W have initial value ranges and value steps, N min + The number of groups of half first axis length H and half second axis length W under the condition of α0, f(H, W) is limited, and each group can meet the air blowing demand. Users can choose a group within the above data to achieve the design of air blowing optical cable according to actual demand and processing technology.

[0078] Regarding the half first axis length H and the half second axis length W and the value range, if the half first axis length H is less than 0.2mm, the wet perimeter of the optical cable 1 in contact with the airflow 缆 is too small, and the gas thrust is insufficient to push the optical cable 1. If the half first axis length H is greater than 0.4mm, the current extrusion process cannot produce smooth and stable convex parts 2, in addition, the half first axis length H is too large and is prone to deformation. Under the premise that the half first axis length H is constant, if the half second axis length W is too small, a high and narrow convex part 2 structure with a high aspect ratio (H / W) is formed, the curvature radius of the convex part 2 decreases, the surface stress concentration coefficient increases, and the compressive strength decreases. Once the outer surface of the convex part 2 is subjected to external force, it is very fragile and easy to be damaged, and even causes other structures to break; if the half second axis length W is too large, the specific surface area of the convex part 2 increases, the actual contact area between the optical cable 1 and the pipeline 5 increases, and under the premise that the dynamic friction coefficient is constant, the friction force between the optical cable 1 and the pipeline 5 increases; and the surface roughness of the optical cable 1 increases, the gas flow field forms a turbulent separation zone on the leeward side of the convex part 2, which reduces the effective wet perimeter of the gas 4 and the optical cable 1, and affects the transmission efficiency of the air blowing force.

[0079] Further, the air blowing compensation coefficient α 缆 is expressed on the parameters of the optical cable 1 as:

[0080] ……(six),

[0081] wherein, 缆 is the wet perimeter length of the optical cable 1, 缆min the theoretical minimum value of is the wet perimeter length of the optical cable 1 without the convex part 2, that is, the circumference of the dedendum circle of the optical cable 1:

[0082] ……(seven),

[0083] In the foregoing steps, the ratio of 凸 and 重合 is calculated, and the maximum value of the ratio is α2. If the calculation time is saved, the ratio of 凸 and 重合 can be simplified to , and can be calculated. Considering the curvature of the convex part 2, the limit value of α2 is about 3.

[0084] Considering the actual production process, if the convex part 2 is designed too compactly, in actual production, the roots of adjacent convex parts 2 may be fused during processing, the fusion area destroys the gas flow sealing, reduces the gas thrust, and not only affects the air blowing effect but also cannot achieve air blowing. In addition, the fusion phenomenon may cause the convex part 2 to be irregular in shape, affect the uniformity and size accuracy of the optical cable 1, damage the structural strength of the optical cable 1, and reduce the mechanical properties of the optical cable 1. Therefore, a balance needs to be achieved between process feasibility, structural reliability, and function implementation, and α2=2.5 is preferred to ensure yield and performance stability.

[0085] Next, α1 will be calculated, as shown in Figure 1 When the optical cable 1 is air-laid, the gas 4 in the pipeline 5 fully develops to form a steady flow state with stable speed. According to the force condition in the pipeline 5, the corresponding fluid micro-element force balance equation is established as follows:

[0086] F 气推 =F 惯 +F 反推 +F 管阻 +F 缆阻 ,

[0087] where F 惯 is the inertial force generated during the flow of the gas 4, which can be expressed by the formula:

[0088] ,

[0089] where ρ 气 is the density of the gas 4 in the pipeline 5, A 气 is the cross-sectional area of the flow of the gas 4 in the pipeline 5, dl is the unit length, dv 气 is the flow rate change of the gas 4, and t is the time. Since the gas flow rate is constant, dv 气 =0, and thus F 惯 =0;

[0090] F 反推 is the counter-thrust of the gas 4, which can be expressed by the formula:

[0091] ,

[0092] Among them, P 气 The pressure of gas 4 inside pipe 5;

[0093] F 管阻 The resistance encountered by gas 4 during its flow through the pipe can be expressed by the following formula:

[0094] ,

[0095] in, 管 τ is the wetted perimeter of pipe 5. 管 The shear stress of pipe 5;

[0096] F 缆阻 The resistance encountered by the optical cable during the flow of gas 4 can be expressed by the following formula:

[0097] ,

[0098] in, 缆 τ is the wetted perimeter length of optical cable 1. 缆 This represents the shear stress of optical cable 1.

[0099] Since both pipe 5 and optical cable 1 are made of similar thermoplastic materials (such as HDPE, PVC, or modified polyolefins), and due to their similar molecular structures and processing techniques, pipe 5 and optical cable 1 have similar roughness. Therefore, according to the Coulomb friction model, when the hardness and roughness of the contact surface materials are similar, the dynamic friction coefficient μ tends to be consistent, making the shear stress between optical cable 1 and pipe 5 stable during the air blowing process. The shear stresses of the two are also similar, which can be considered as τ. 管 =τ 缆 Therefore, the parameter τ is introduced. 均 To replace τ 管 and τ 缆 The value.

[0100] The above force equilibrium equation for the fluid element can be simplified to:

[0101] ……(eight).

[0102] Since the gas flow velocity is constant, the inertial force generated by the motion of gas 4 is zero. Therefore, the above force balance equation for the fluid element simplifies to:

[0103] ,

[0104] in, 总 express 缆 and 管 .

[0105] According to the Darcy-Weisbach formula, ,

[0106] where d h is the hydraulic diameter, and λ is the frictional resistance coefficient,

[0107] ,

[0108] where R h is the hydraulic radius,

[0109] ,

[0110] Therefore, the above force balance equation of the fluid microelement can be simplified as:

[0111] … (IX).

[0112] Therefore, the thrust of the gas 4 can be derived as:

[0113] … (X).

[0114] The frictional resistance coefficient λ can be calculated according to the Reynolds number Re and the Colebrook formula.

[0115] ,

[0116] where Re is the Reynolds number. During the installation of the air-blowing cable, in order to push the optical cable 1 to move in the pipeline 5, the air flow speed is usually high, and the diameter of the pipeline 5 used by the optical cable 1 is usually large, which will cause the Reynolds number to be large, and the Reynolds number is usually much larger than 4000, and the air flow is usually in a turbulent state.

[0117] ,

[0118] where μ 气 is the dynamic viscosity of the gas 4,

[0119] ,

[0120] where ε is the absolute roughness of the inner wall of the pipeline 5.

[0121] Through the above steps, F 气推 can be calculated.

[0122] During the installation of the optical cable 1 into the pipeline 5, the friction per unit length is:

[0123] ……(eleven),

[0124] Where: G is the weight of optical cable 1, g is the acceleration due to gravity, and g is taken as 9.8 m / s². 2 μ is the coefficient of friction, which is determined based on the material.

[0125] F is obtained through the above calculations. 摩 With F 气推 The ratio of α to β, the minimum value of which is α. 缆 The lower bound of the value of α. 缆 After the range of values ​​for F, 气推min With α 缆min The minimum thrust required, obtained by multiplying the product of the two forces, can achieve a balance with the frictional force.

[0126] The present invention also provides an air-blown optical cable, wherein the protrusion 2 of the optical cable 1 can be designed according to the protrusion design method of the air-blown optical cable based on air thrust compensation as described above.

[0127] Based on the above calculation method, the sum of the areas S of all protrusions 2 can be calculated. 凸 The sum of the areas of all the recesses 3, S 凹 .

[0128] The sum of the areas S of all the protrusions 2 on the radial section 凸 The area A of a single convex part 2 凸 Multiply by the number N of the convex part 2.

[0129] The area A of a convex part 2 凸 It approximates the area of ​​half an ellipse, but in reality, there is an overlap between the half ellipse and the root circle. Therefore, the actual area A of a convex part 2 is... 凸 The area of ​​the half-ellipse minus the area of ​​the portion where the half-ellipse coincides with the root circle is the area of ​​the half-ellipse, i.e.:

[0130] ……(twelve),

[0131] Among them, the area A of the semi-ellipse 半个椭圆 for:

[0132] ……(Thirteen),

[0133] Area A of the overlapping part 重合 for:

[0134] ……(fourteen);

[0135] Therefore, substituting formulas (xiii) and (xiv) into formula (xiv) yields:

[0136] ……(fifteen).

[0137] Therefore, the area S of all the recesses 3 凹 Subtract the area of ​​the tooth cusp circle from the area of ​​the tooth root circle, and then subtract the sum of the areas of all the protrusions 2, S. 凸 That is, the area S of all the concave parts 3 凹 for:

[0138] ……(sixteen);

[0139] The area S of the tooth tip circle 齿尖 for:

[0140] ... (17)

[0141] The area S of the root circle 齿根 for:

[0142] ……(eighteen);

[0143] Among them, R 齿尖 The radius of the tooth tip circle;

[0144] Then, substituting formulas (xv), (xvii), and (xviii) into formula (xvii), the sum of the areas S of all the recesses 3 of the optical cable 1 is... 凹 for:

[0145] ……(nineteen).

[0146] Based on the above calculation method, and assuming the air-blown cable requirements are met, the wetted perimeter ratio α is calculated for existing large-core-count optical cables 1 (144 cores and above). 缆 Minimum number of teeth N min+ The sum of the areas of all the recesses 3, S 凹 The results are shown in the table below:

[0147]

[0148] As can be seen from the table above:

[0149] 144-core optical fiber cable can use S 凹 The range is 3.9125mm. 2 ~7.0268mm 2 ;

[0150] 288-core optical fiber cable can use S 凹 The range is 4.1025mm. 2~ 7.0600mm 2 ;

[0151] 432-core optical fiber cable can use S 凹 The range is 4.4357mm. 2 ~7.3966mm 2 ;

[0152] 864-core optical fiber cable can use S 凹 The range is 5.2673mm. 2 ~6.9523mm 2 ;

[0153] 1008-core optical fiber can use S 凹 The range is 5.7821mm. 2 ~7.4693mm 2 .

[0154] Therefore, while meeting the requirements for air-blown cable delivery, the sum of the areas of all recesses 3, S, can be set. 凹 The range is 5.2673mm. 2 ≤S 凹 ≤6.9523mm 2 It is quite suitable.

[0155] Under existing processing conditions, the key to optimizing the air-blown cable effect lies in reasonably controlling the total area S of the concave portion 3 on the surface of the optical cable 1. 凹 The range of this parameter needs to be set within an appropriate range; too large or too small a range will have an adverse effect on the air blowing performance.

[0156] If the area of ​​the concave part is S 凹 If the spacing is too small, it will first be limited by the current high-temperature and high-pressure extrusion process. During processing, an excessively small spacing between the recesses 3 can easily cause the materials of adjacent protrusions 2 to stick together, thereby compromising the structural integrity of the optical cable 1 surface. Secondly, from an aerodynamic performance perspective, insufficient space in the recesses 3 will reduce the effective cross-sectional area of ​​the airflow channel, decrease the contact wetted perimeter between the gas 4 and the optical cable 1, and thus weaken the gas thrust. In addition, S 凹 If the number of recesses 3 is insufficient, then the number of protrusions N on the surface of the optical cable 1 will be more. This will increase the contact points and contact area between the optical cable 1 and the inner wall of the pipe 5, exacerbate the adhesion effect between the inner wall of the pipe 5 and the protrusions 2, and further reduce the air blowing efficiency.

[0157] Conversely, if the area of ​​the concave part S 凹 Excessive size of the recesses 3 will also bring a series of problems. Too many recesses 3 will reduce the number of protrusions N, requiring each protrusion 2 to bear greater supporting force and frictional stress. This may not only exceed the structural strength limit of the protrusion 2, accelerating the wear of the sheath material, but also affect the stability of the air-blowing process. Simultaneously, excessively large recesses 3 will make the tooth root circular area of ​​the optical cable 1 more likely to come into direct contact with the tube wall, increasing frictional resistance. From a fluid dynamics perspective, an excessively large recess area S...凹 The air flow will reduce the contact wet area with the optical cable 1, reduce the additional thrust generated by the gas 4, make it difficult to balance the pipe wall friction resistance, and cause the conveying efficiency to decrease. More seriously, the concave part 3 occupies too high a proportion, which will cause insufficient support points, so that the positioning and support effect of the optical cable 1 in the pipeline 5 will be poor, which will seriously affect the air blowing performance.

[0158] Therefore, according to the air blowing compensation coefficient α 缆 , the convex part 2 and the concave part 3 parameters can meet the air blowing cable laying requirements of the existing large-core optical cable 1. For optical cables 1 with 1008 cores and above, the air blowing cable laying method is usually not used.

[0159] The convex part design method and the air blowing optical cable based on the air pushing compensation provided by the application are based on the theory of mechanics and fluid dynamics, and provide a universal thrust compensation model for the laying of the air blowing optical cable. The critical thrust threshold is used to predict the air blowing compensation coefficient α 缆 , which can avoid the interruption of construction caused by insufficient thrust in advance, reduce the rework rate and resource waste. According to the air blowing compensation coefficient α 缆 , the related parameters of the optical cable 1 are directly related to the structure parameters (such as the shape) of the convex part 2, the mathematical relationship between the size, distribution and gas thrust of the convex part 2 is clear, a standardized parameter matching method is provided, the manual trial and error cost is reduced, the calculation process is simplified, the design efficiency is improved, the limitations of the empirical formula are avoided, the one-time laying success rate is improved, a reusable technical framework is provided for the industry, efficient calculation, accurate compensation, reliable construction, and cost optimization are comprehensively improved, and it is especially suitable for large-core optical cable 1 laying scenes.

[0160] It should be understood that although the present specification is described in terms of embodiments, each embodiment does not contain only one independent technical solution, and the description of the specification is only for the sake of clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that those skilled in the art can understand.

[0161] The series of detailed descriptions listed above are only specific descriptions of the feasible embodiments of the application, and are not intended to limit the protection scope of the application. Any equivalent embodiments or changes made without departing from the spirit of the application should be included in the protection scope of the application.

Claims

1. A method for designing the protrusion of an air-blown optical cable based on air thrust compensation, characterized in that, The optical cable (1) includes a circular cable body, with several protrusions (2) evenly distributed around the circumference of the cable body. A concave part (3) is formed between two adjacent protrusions (2). The circle in which the cable body is located is the root circle of the tooth, and the circle formed by the ends of the protrusions (2) away from the cable body is the tip circle of the tooth. The outline of the protrusion (2) is a semi-ellipse, and the two endpoints of the semi-ellipse in the tangential direction of the cable body are located on the root circle of the tooth. The design steps are as follows: S1. Introduce the air-blowing compensation coefficient α 缆 , , ……(one); F 摩 F is the frictional force per unit length of the optical cable (1). 气推 The thrust per unit length of the gas (4); ……(two); 凸 Let the arc length of a convex part (2) be , 重合 The arc length of the part where the convex part (2) coincides with the root circle; ……(three); e is the eccentricity of the half ellipse, E(e) is the complete elliptic integral of the second kind, H is the length of the longest axis of the half ellipse in the radial direction of the optical cable (1), 0.2mm≤H≤0.4mm, W is half the length of the two endpoints of the half ellipse in the tangential direction of the cable body, 0.15mm≤W≤0.4mm. ……(Four); R 齿根 The radius of the tooth root circle; Substitute formulas (III) and (IV) into formula (II) to establish a mathematical model of H, W and α2; set the step size △H=0.01mm, △W=0.01mm, iterate through the values ​​of H and W and substitute them into the above mathematical model, and take the maximum value of the calculation result as α2. S2. Calculate the minimum number N of convex parts (2). min + ; Quantity of convex parts (2) ...(5); α0 is a constant taken between (α1, α2). 缆min The minimum wetted perimeter length of the optical cable (1); Based on the step size ΔH and ΔW, iterate through the values ​​of H and W and substitute them into formula (V) to calculate the minimum value N. min Round up to get N min + ; S3. N min + Substituting into formula (5), we obtain the relationship between H and W, f(H, W). Based on the range of H and W, step size, f(H, W), and requirements, we select the values ​​of H and W.

2. The protrusion design method for air-blown optical cable based on air thrust compensation according to claim 1, characterized in that: ……(six), in, 缆 is the wetted perimeter length of the optical cable (1).

3. The protrusion design method for air-blown optical cable based on air thrust compensation according to claim 2, characterized in that: α2=3。 4. The protrusion design method for air-blown optical cable based on air thrust compensation according to claim 1, characterized in that: ……(ten), Where λ is the friction coefficient, ρ 气 v is the density of the gas (4) inside pipe (5). 气 dl is the velocity of the gas (4) flow and dl is the unit length.

5. The protrusion design method for air-blown optical cable based on air thrust compensation according to claim 4, characterized in that: ， Where Re is the Reynolds number, ， Where, μ 气 The dynamic viscosity of gas (4) is... ， Where ε is the absolute roughness of the inner wall of pipe (5).

6. The protrusion design method for air-blown optical cable based on air thrust compensation according to claim 1, characterized in that: ……(eleven), Where G is the weight of the optical cable (1), g is the gravitational acceleration, and g = 9.8 m / s². 2 μ is the coefficient of friction.

7. The protrusion design method for air-blown optical cable based on air thrust compensation according to claim 1, characterized in that: ……(seven).

8. An air-blown optical cable, characterized in that: The protrusion (2) of the optical cable (1) can be designed by the protrusion design method of the air-blown optical cable based on air thrust compensation according to any one of claims 1 to 7.

9. The air-blown optical cable according to claim 8, characterized in that: The sum of the areas S of all the recesses (3) of the optical cable (1) 凹 for: ……(nineteen), Among them, R 齿尖 The radius of the tooth tip circle.

10. The air-blown optical cable according to claim 9, characterized in that: 5.2673mm 2 ≤S 凹 ≤6.9523mm 2 。

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