Fan blade inner heating air pipe mounting structure and mounting method

Abstract

This invention discloses an installation structure and method for heating air ducts inside wind turbine blades. The heating air ducts are flexible, comprising a main duct and branch ducts. The diameter of the main duct decreases sequentially from the front to the rear. The branch ducts are arranged along the length of the main duct and connected to it. The outlets of each branch duct face both sides of the leading edge of the blade, and the effective coverage areas of each branch duct are interwoven, covering the area on the inner surface of the blade that needs heating. The front end of the main duct connects to the outlet duct of the heater. A fixing anchor plate is arranged on the blade web at the rear end of the main duct, with pulleys mounted on the anchor plate. A rope is wound around the pulley, with one end fixed to a suitable position convenient for personnel to operate in the leading edge cavity of the blade, and the other end connected to the rear end of the main duct. This invention provides convenient transportation, rapid installation, and precise delivery of hot air as needed, with high heat exchange efficiency between the hot air and the inner surface of the blade.

Description

Technical Field

[0001] This invention relates to air-heat de-icing of wind turbine blades, specifically to an installation structure and method for a heating duct inside a wind turbine blade. Background Technology

[0002] Traditional wind turbine blades are not designed with the addition of heat-based de-icing equipment in mind during manufacturing. Therefore, installing heat-based de-icing equipment within traditional wind turbine blades requires specific construction and weight control measures to strictly avoid excessive load that could compromise the blade's structural safety. Furthermore, the different materials and thicknesses in different areas of the blade mean that the heat required for de-icing varies from region to region. Heat must be delivered strategically to the corresponding areas to improve heat exchange efficiency, reduce heat loss, and enhance de-icing effectiveness. The sealed environment inside the blade, the narrow space at the front and middle sections making manual operation impossible, and the fact that the blades are located tens of meters above the ground on the wind turbine further restricts the size and weight of the equipment that can be transported.

[0003] The existing air-heated de-icing technology on the market uses ducts made of rigid materials, which need to be transported in many sections to the inside of the blades, where they are assembled, sealed, and fixed. The construction is complex, time-consuming, and heavy, and it puts a large load on the overall blades. Summary of the Invention

[0004] The technical problem to be solved by this invention is that the heating duct is inconvenient to install when the traditional fan is modified for air-heat de-icing. This invention provides a heating duct installation structure and method for the fan blades that is easy to transport, can be installed quickly, and can accurately deliver hot air to the icing area.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A heating duct installation structure for a fan blade includes a blade web installed inside the fan blade, a heater for providing heating gas, a baffle installed on the blade web, and a flexible duct made of a flexible material, wherein the flexible duct extends along the longitudinal axis of the blade web. Its structural features are as follows: The flexible duct includes a main duct and several branch ducts. The diameter of the main duct decreases from the front end to the rear end. The branch ducts are arranged along the length of the main duct and are connected to the main duct. The air outlets of each branch duct are arranged facing the two sides of the leading edge of the blade. The air outlets of each branch duct cover the effective range of each branch duct and interweave with each other. The air outlets of each branch duct cover the area on the inner surface of the blade that needs to be heated. The front end of the main air duct is connected to the air outlet duct of the heater. A fixed anchor plate is arranged on the blade web at the rear end of the main air duct. A pulley is installed on the fixed anchor plate, and a rope is wound around the pulley. One end of the rope is fixed in a suitable position in the leading edge cavity of the blade for easy operation by personnel, and the other end is connected to the rear end of the main air duct.

[0006] The flexible duct of this invention is made of highly flexible, ultra-lightweight, airtight, and low-elongation material. The entire flexible duct inside the blade can be folded up, transported to the inside of the blade, and then unfolded and fixed, which greatly facilitates transportation and installation and shortens the installation time. At the same time, the weight of the flexible duct is controlled at 240 grams per meter, which is only 1 / 10 of that of rigid material ducts. It basically does not affect the structural load of the fan blades. During the transportation of hot air, it will not expand excessively due to wind pressure and will not leak air. Moreover, when the flexible duct rotates with the fan blades, it is subjected to centrifugal force far exceeding its own weight. This centrifugal force can keep the flexible duct in an extended state and give it reliable fatigue strength to meet the needs of long-term use.

[0007] The flexible air duct of this invention includes a main air duct and branch air ducts. The main air duct has branch air ducts arranged at regular intervals on its side for side air outlets. The air outlets of each branch air duct are arranged facing both sides of the leading edge of the blade, allowing hot air to be precisely, rapidly, and at close range sprayed onto locations within the blade cavity requiring a larger heating amount, such as... Figure 1 The blade sandwich layer 76 shown allows hot air to move at high speed within the flexible duct, resulting in short travel time and minimal heat loss. The main duct outlet can also spray hot air towards the narrow space at the blade tip, significantly increasing the remaining temperature of the hot air upon arrival. By adjusting parameters such as the distance between the branch duct outlet and the inner wall of the blade, the diameter of the branch duct outlet, and the spacing between the branch duct outlets, the effective coverage areas of each branch duct can be interwoven, and the airflow from each branch duct can cover all areas of the inner surface of the blade that require heating.

[0008] According to embodiments of the present invention, the present invention can be further optimized, and the optimized technical solution is as follows: In one preferred embodiment, the branch ducts are symmetrically arranged on both sides of the main duct to achieve more uniform air delivery.

[0009] In one preferred embodiment, the fixing anchor plates are symmetrically arranged on the blade web at the rear end of the main air duct, and the ropes are installed on both sides of the main air duct to make the installation of the flexible air duct more stable and reliable, and to prevent the flexible air duct from swinging or folding when the blades rotate.

[0010] In one preferred embodiment, the fixed anchor plate includes a pulley upper limit plate, an anchor plate bonding base plate, a pulley fixing shaft installed between the pulley upper limit plate and the anchor plate bonding base plate, and a pulley installed on the pulley fixing shaft.

[0011] In one preferred embodiment, the flexible duct is made by hot-pressing and bonding of fabric.

[0012] In one preferred embodiment, the main duct adopts a constricted structure with a large inlet diameter at the front end and a small outlet diameter at the rear end. This not only ensures sufficient air pressure and velocity at the outlet of the main duct and the outlet of the branch ducts, but also allows the main duct to extend into areas inaccessible to personnel within the blades for air delivery. The sum of the cross-sectional area of ​​the rear outlet of the main duct and the side outlet cross-sectional areas of all branch ducts is less than the cross-sectional area of ​​the front inlet of the main duct to avoid a drop in air pressure.

[0013] In one preferred embodiment, the front end of the main air duct is connected to the air outlet duct of the heater by means of a locking band.

[0014] In one preferred embodiment, a loop is provided at the rear end of the main air duct, and the rope is connected to the main air duct via the loop.

[0015] Based on the same inventive concept, the present invention also provides an installation method for the heating duct installation structure inside the fan blades, which includes the following steps: S1. Connect the front end of the main air duct to the air outlet duct of the heater to complete the installation of the front end of the flexible air duct; S2. Apply glue evenly to the bottom surface of the anchor plate; S3. Connect one end of the rope to the rear end of the main air duct, and pass the other end of the rope through the pulley on the fixed anchor plate and make a round trip, leaving it near the baffle. S4. First, use the robot to clamp the entire anchor plate and move it to the position on the blade web surface where it needs to be fixed. Then, the robot places the anchor plate at the fixed point and maintains the clamping force and downward pressure to prevent the anchor plate from slipping. Next, the robot's heating device heats the glue applied to the surface of the anchor plate to accelerate the curing of the glue. Finally, the glue cures between the anchor plate and the blade web, and the anchor plate is installed. S5. Pull the end of the rope near the baffle to move the rear end of the main air duct toward the fixed anchor plate until the main air duct is completely straightened. Then, tie the end of the rope near the baffle to a suitable position in the blade leading edge cavity where it is convenient for personnel to operate.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention overcomes the technical bottleneck of achieving uniform heat exchange in air-heated de-icing: Traditional air-heated de-icing technology for wind turbine blades has long faced a core challenge: after hot air enters the complex, tens-of-meters-long blade cavity, the airflow velocity changes drastically (e.g., Figure 7As shown, near the baffle (A), due to the large cross-sectional area of ​​the blade's leading edge cavity, the wind speed rapidly decreases from the initial 20 m / s to 2.05 m / s; in the middle section (B), due to the gradually decreasing cross-sectional area of ​​the blade's leading edge cavity, the wind speed increases from 2.05 m / s to 5 m / s; and in the front section (C), the cross-sectional area of ​​the blade's leading edge cavity further decreases, causing the wind speed to further increase to 12 m / s. This results in a mismatch of heat energy, with heat concentrated in non-critical de-icing areas (near the baffle (A)). Meanwhile, critical icing-prone areas such as the front and windward sides of the blade receive less heat and have insufficient heat exchange, making effective heating and de-icing impossible. This invention solves the problem of long-distance, controllable, and uniform hot air delivery within the blade by installing flexible ducts in the blade's leading edge cavity to deliver air towards the blade tip. These flexible ducts include a main duct and several branch ducts. The diameter of the main duct decreases sequentially from the front to the rear, and the outlets of each branch duct are arranged facing both sides of the blade's leading edge (blade core layer). Figure 8 As shown, the wind speed in the main duct near the baffle A is 20 m / s higher than the initial wind speed, the wind speed at the outlet of the branch duct in the middle section of the blade leading edge cavity B can reach 15 m / s, and the wind speed at the front part of the blade leading edge cavity C can reach 12 m / s. This is not just simple air supply, but achieves efficient heat exchange between hot air and the inner wall of the blade cavity, ensuring a uniform temperature field at the overall leading edge of the blade. Thus, while ensuring the de-icing effect, it avoids thermal damage and waste of heat energy caused by local overheating to the composite material blade.

[0017] 2. This invention achieves a balance between lightweight design and structural safety. Wind turbine blades are extremely sensitive to loads. This invention uses flexible ducts made of ultra-lightweight materials for heating. Compared to traditional rigid metal or composite material ducts, it not only has significant lightweight advantages but also changes the duct design concept: transforming the passive adaptation of the duct to the blade structure used in traditional air-heated de-icing technology into an active collaboration between the duct and the blade structure. Rigid ducts, as rigid bodies, significantly increase the unbalanced torque and rotational inertial load of the wind turbine blades due to their own mass, potentially altering the natural frequency of the blades and leading to fatigue risks. The ultra-lightweight flexible ducts used in this invention add almost no additional structural load, providing de-icing functionality to the wind turbine blades without sacrificing the original structural safety margin. This is particularly important for large (hundred-meter-class) wind turbine blades.

[0018] 3. This invention solves the engineering challenges of construction in confined spaces. The interior of wind turbine blades is a typical confined space, with a narrow cross-section and extremely long depth, making it difficult for personnel to enter and work deep inside. The flexible duct installation and fixing method in this invention enables reliable long-distance, blind operation of duct installation inside wind turbine blades. Traditional rigid ducts require personnel to perform precise docking, flange tightening, and sealing inside the blade, which is difficult and poses personnel safety risks. This invention uses robots and ropes to pull the flexible duct to a pre-set fixing point at the blade tip, a position inaccessible to personnel. All installation operations are performed outside the blade root or in a limited area accessible to personnel. After the flexible duct is inserted deep into the leading edge cavity of the blade, it automatically fits the blade web through rope traction, thus transforming the complex assembly inside the blade cavity into simple traction and positioning, significantly reducing the difficulty and operational risks of duct installation.

[0019] 4. This invention establishes a highly efficient construction mode integrating "transportation-installation-sealing". The flexible duct of this invention can be folded and packaged, achieving one-time delivery, integral forming, and self-sealing. This invention revolutionizes the traditional discrete construction process of rigid ducts: In terms of logistics, it overcomes the limitations of equipment hoisting capacity in high-altitude operations. Rigid ducts are limited by the size of tower doors and platform openings, requiring segmented transportation, while flexible ducts can be transported as a whole on the tower, through the hub compartment, and into the blades. In terms of process, the multi-section assembly of rigid ducts is not only time-consuming, but the inter-section sealing is also a weak point; leakage will directly lead to the failure of the de-icing system. As a continuous integral structure, the flexible duct eliminates a large number of physical interfaces, avoiding the high-risk failure point of interface leakage from the design, significantly improving the long-term operational reliability of the system.

[0020] 5. This invention constructs a lightweight, feasible, efficient, and highly reliable air-thermal de-icing system solution. Instead of simply pursuing increased heating power, this invention addresses the pain points of the wind power industry—namely, the inability to install air-thermal de-icing systems, slow installation, risks, and uneven performance—through a synergistic approach of material innovation (using ultra-lightweight flexible materials to create flexible ducts), structural innovation (continuous flexible ducts along their entire length), and installation process innovation (blind installation and traction within the blades). This transforms the de-icing system from an "additional, bulky piece of equipment" into a "functional layer deeply integrated with the blades," which has substantial value in improving the power generation efficiency and safety of wind turbines in freezing environments. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a cross-section of the flexible duct and blades, and a schematic diagram of the air outlet of the branch duct.

[0023] Figure 2 This is a general structural diagram of the heating duct installation structure inside the fan blades.

[0024] Figure 3 This is a diagram of the fixed structure at the end of the main duct.

[0025] Figure 4 A top view of the fixed structure at the end of the main duct.

[0026] Figure 5 Right view of the fixed structure at the end of the main duct.

[0027] Figure 6 This is a top view of the flexible duct structure arranged along the length of the blade inside the blade.

[0028] Figure 7 This is a schematic diagram showing the airflow direction and velocity of a blade without a flexible duct inside.

[0029] Figure 8 This is a schematic diagram showing the airflow direction and velocity of a flexible duct inside the blade.

[0030] Figure 9 This is a schematic diagram of the jet flow field at the outlet of a branch duct.

[0031] In the diagram: 1. Main duct; 11. Main duct outlet; 2. Branch duct; 3. Locking strap; 4. Rope; 5. Ring buckle; 6. Fixed anchor plate; 601. Pulley; 602. Pulley fixing shaft; 603. Pulley upper limit plate; 604. Anchor plate bonding base plate; 7. Wind turbine blade; 71. Blade leading edge cavity; 72. Blade web cavity; 73. Blade trailing edge cavity; 74. Blade mold seam; 75. Blade pure fiberglass layer; 76. Blade core layer; 77. Blade spars; 8. Blade web; 81. Leading edge web; 82. Trailing edge web; 9. Heater; 91. Air outlet duct; 10. Baffle; A. Near the baffle; B. Middle section of the blade leading edge cavity; C. Front part of the blade leading edge cavity. Detailed Implementation

[0032] The present invention will be further described below with reference to specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0033] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Please see Figure 1 - Figure 6 An embodiment of the heating duct installation structure inside the wind turbine blade of the present invention includes a blade web 8 installed inside the wind turbine blade 7, a heater 9 for providing heating gas, a baffle 10 installed on the blade web 8, and a flexible duct made of ultra-light flexible material, wherein the flexible duct extends along the longitudinal axis of the blade web 8.

[0036] It should be noted that the wind turbine blade 7 is a known structure, and the present invention focuses on adding a flexible heat-conducting duct inside the existing wind turbine blade 7. Typically, the heat conduction is best at the blade mold joint 74 of the wind turbine blade 7, the heat conduction of the pure fiberglass layer 75 of the blade is average, the heat conduction of the blade sandwich layer 76 is poor, and the heat conduction of the blade spar 77 is average.

[0037] In this embodiment, the blade web 8 includes a leading edge web 81 and a trailing edge web 82. The leading edge web 81 and the trailing edge web 82 divide the blade cavity into a leading edge cavity 71, a blade web cavity 72 and a trailing edge cavity 73. Obviously, the present invention is not limited to this type of wind turbine blade 7. The structure of the present invention can also be used for blade structures in which only a single blade web 8 is arranged in the blade cavity.

[0038] The flexible duct includes a main duct 1 and several branch ducts 2. The main duct 1 has a large inlet diameter and a small outlet diameter, with the diameter decreasing sequentially from the inlet (front end) to the outlet (rear end). The branch ducts 2 are arranged along the length of the main duct 1 and are connected to the main duct 1. The air outlets of each branch duct 2 are arranged facing both sides of the leading edge of the blade (i.e., the blade sandwich layer 76 with poor thermal conductivity). The air outlets of each branch duct 2 cover the effective range of each other, and the air outlets of each branch duct 2 cover all areas of the inner surface of the blade that need to be heated. The front end of the main air duct 1 is connected to the air outlet duct 91 of the heater 9 by a locking band 3. A fixing anchor plate 6 is arranged on the blade web 8 at the rear end of the main air duct 1. A pulley 601 is installed on the fixing anchor plate 6. A rope 4 is wrapped around the pulley 601. One end of the rope 4 is fixed in a suitable position inside the blade leading edge cavity 71 for easy operation by personnel, and the other end is connected to the ring buckle 5 at the rear end of the main air duct 1.

[0039] Preferably, the branch ducts 2 are symmetrically arranged on both sides of the main duct 1. The length of the branch ducts 2 decreases sequentially along the length direction of the main duct 1 to adapt to the internal cavity structure of the fan blades 7 and to achieve uniform air delivery to the inner wall of the blade leading edge cavity.

[0040] The fixing anchor plates 6 are symmetrically arranged on the blade web plate 8 at the rear end of the main air duct 1, and the ring buckles 5 are symmetrically arranged on both sides of the rear end of the main air duct 1. The ropes 4 are symmetrically installed on both sides of the main air duct 1 through the ring buckles 5 and the fixing anchor plates 6.

[0041] The fixed anchor plate 6 includes a pulley upper limit plate 603, an anchor plate bonding base plate 604, a pulley fixing shaft 602 installed between the pulley upper limit plate 603 and the anchor plate bonding base plate 604, and a pulley 601 installed on the pulley fixing shaft 602.

[0042] To avoid a drop in air pressure, the sum of the cross-sectional area of ​​the main duct outlet 11 and the side outlet cross-sectional areas of all branch ducts 2 is less than the front inlet cross-sectional area of ​​the main duct 1.

[0043] The installation and usage process of the flexible duct of this invention is as follows: The main duct 1 and branch duct 2 are each made of canvas material and formed into flexible ducts through sewing, bonding, and hot pressing. The ring 5 is sewn to both sides of the rear end of the variable diameter main duct 1 at a certain angle to facilitate lateral force distribution.

[0044] When installing the flexible duct, first put the front end of the main duct 1 onto the outer surface of the air outlet duct 91 of the heater 9, and then use multiple locking straps 3 to lock and fix it onto the air outlet duct 91 of the heater 9 to complete the installation of the front end of the flexible duct.

[0045] The pulley 601, pulley fixing shaft 602, pulley upper limit plate 603, and anchor plate bonding base plate 604 are assembled together to form the fixed anchor plate 6. After assembly, a certain thickness of glue is evenly applied to the bonding surface of the anchor plate bonding base plate 604.

[0046] One end of the rope 4 is passed through the loop 5 and several fixed joints are made to fix the rope 4 to the loop 5. The other end of the rope 4 is passed through the pulley 601 and looped around once to form a back-and-forth motion. After that, it stays near the baffle 10.

[0047] A robot grips the entire anchor plate 6 and moves it to the desired fixing position on the surface of the blade web 8. The robot places the anchor plate 6 at the fixing point, maintaining clamping force and downward pressure to prevent slippage. A heating device on the robot heats the adhesive applied to the surface of the anchor plate 6, accelerating curing. Finally, the adhesive cures between the anchor plate 6 and the blade web 8, completing the installation of the anchor plate 6. One set of the present invention comprises two anchor plates 6, installed side-by-side on the blade web 8.

[0048] Pulling rope 4 causes the rear end of the main duct 1 of the flexible duct to move towards the fixed anchor plate 6 until the main duct 1 is completely straightened. Finally, the end of rope 4 is tied to a suitable position inside the leading edge cavity 71 of the blade for easy operation. There is a ring 5 and a fixed anchor plate 6 on each side of the main duct outlet 11. After securing the main duct 1 with rope 4, it ensures that the flexible duct will not rotate during blade rotation, thus ensuring the directionality of the lateral air outlet of the branch duct 2. The installation of the flexible duct is complete after the ropes 4 on both sides of the main duct 1 are secured.

[0049] To verify the heat exchange effect, please combine Figure 7 - Figure 9 As shown, the following calculations are performed regarding the heat exchange effect of the flexible duct: Without a flexible duct, hot air exits from the outlet duct 91 of the heater 9 and enters the larger blade cavity. The main duct inner diameter of the flexible duct of this invention is Φ200mm, the air velocity inside the duct is 20m / s, and the average cross-sectional area of ​​the blade cavity is 0.306m². 2 Based on the fluid dynamics formula relating flow rate, velocity, and cross-sectional area, the average air velocity within the blade cavity without flexible ductwork is calculated to be V = 2.05 m / s. The specific fluid dynamics formula is as follows: (1), Q: Volumetric flow rate, unit m³ 3 / s; V: Average wind speed, in m / s; A: Cross-sectional area, unit m 2 .

[0050] After analyzing the cross-sectional area of ​​the blade, the inner cavity of the blade is approximated as a pipe with a diameter D = 0.62 m. The heat transfer efficiency is calculated using formulas such as the Dittus-Boelter equation in heat transfer, and the corresponding formulas are as follows: Re=V×D / u (2) Nu=0.023Re0.8Pr0.3 (3) h=Nu×λ / D (4) Re: Reynolds number; V: Average wind speed, in m / s; u: Kinematic viscosity of hot air, in meters (m³) 2 / s; D: Pipe diameter, in meters; Nu: Nusel number; Pr: Prandtl coefficient for hot air; h: Heat transfer coefficient, unit W / (m²) 2 ·K); λ: Thermal conductivity of hot air, unit W / (·K); Substituting the pipe diameter D = 0.62 m, the average wind speed within the blade leading edge cavity V = 2.05 m / s, and the air physical properties at 70℃: kinematic viscosity u = 0.00002002 m 2 / s; Prandtl coefficient Pr=0.694; thermal conductivity λ=0.0283W / (M·K); calculated using formulas (2)-(4): Re=63468; Nu=143.28; h=6.54 W / (m 2 ·K).

[0051] When using flexible ducts, some hot air is ejected from the outlet of branch duct 2, and the heat exchange method changes from forced convection heat exchange within the duct to jet heat exchange. According to the flow field analysis of a circular nozzle, its heat transfer coefficient is related to the temperature and velocity of the jet, the nozzle diameter, and the distance between the nozzle and the wall. The flow field analysis diagram for a circular nozzle is shown in the attached diagram. Figure 9 The specific calculation formula is as follows: Within a circle centered at the stagnation point and with radius r, the average heat transfer coefficient of the impacted surface (e.g., the inner wall of the blade leading edge cavity) can be expressed as a function in the following form: (5) (6) The qualitative temperature is taken as (t) w +t ∞ ) / 2, the experimental verification range is: (7).

[0052] The air velocity inside the flexible duct is 20 m / s, and the air temperature is 70℃. From the effective experimental verification range of formula (7), 2≤H / D≤12, 2.5≤r / D≤7.5, we can obtain that the outlet spacing of branch duct 2 is 0.37m, then r=0.185m, and the outlet diameter D 口 =0.025m, the length of each branch duct conforms to the shape change of the blade cavity, maintaining the distance H between its outlet and the cavity wall at 0.3m; at this time, H / D 口 =12, r / D 口 =7.4, all within the valid range of the formula.

[0053] The highest wind speed at the branch duct outlet is approximately 20 m / s, and the lowest wind speed around the perimeter is approximately 5 m / s. Based on the wind speed distribution across the cross-sectional area, the average outlet wind speed is taken as V = 15 m / s; given r = 0.185 m, D 口 =0.025m, H=0.3m, the calculation is as follows: Re D =(V×D 口 ) / u=(15×0.025) / 0.00002002=18731 (According to formula (2)) Nu D =2Re D 0.5 Pr 0.42 (1+0.005Re) D 0.55 ) 0.5 ×(1-1.1D 口 / r) / (1+0.1(H / D) 口 -6)D 口 / r)×D 口 / r =2×18731 0.5 ×0.694 0.42 ×(1+1.119) 0.5 ×0.851 / (1+0.081)×0.025 / 0.185 =36.38 (According to formula (6)) h m =Nu D ×λ / D 口 =36.38×0.0283 / 0.025=41.18W / (m 2 · K) (according to formula (5)).

[0054] The calculations above show that, without flexible ductwork, the hot air flows along the leading edge cavity via convective heat transfer, with a heat transfer coefficient of 6.54 W / (m²). 2When using flexible ducts with branch ducts, the hot air ejected from the branch ducts transfers heat to the cavity wall via jet heat transfer, with a heat transfer coefficient of 41.18 W / (m²). 2 The heat transfer coefficient (K) is 6.29 times that of the system without flexible ductwork.

[0055] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention, or modify it into equivalent embodiments with equivalent changes, without departing from the scope of the technical solution of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention should fall within the scope of protection of the technical solution of the present invention.

Claims

1. A heating duct installation structure inside a wind turbine blade, comprising a blade web installed inside the wind turbine blade, a heater for providing heating gas, a baffle installed on the blade web, and a flexible duct made of a flexible material, wherein the flexible duct extends along the longitudinal axis of the blade web, characterized in that: The flexible duct includes a main duct (1) and several branch ducts (2). The diameter of the main duct decreases from the front end to the rear end. The branch ducts are arranged on the main duct along the length of the main duct and are connected to the main duct. The air outlets of each branch duct are arranged facing the two sides of the leading edge of the blade. The air outlets of each branch duct cover the effective range of each branch duct and interweave with each other. The air outlets of each branch duct cover the area on the inner surface of the blade that needs to be heated. The front end of the main air duct is connected to the air outlet duct of the heater. A fixed anchor plate (6) is arranged on the blade web at the rear end of the main air duct. A pulley (601) is installed on the fixed anchor plate. A rope (4) is wrapped around the pulley. One end of the rope (4) is fixed in a position that is convenient for personnel to operate in the leading edge cavity of the blade, and the other end is connected to the rear end of the main air duct.

2. The heating duct installation structure inside the fan blades according to claim 1, characterized in that, The branch ducts are symmetrically arranged on both sides of the main duct.

3. The heating duct installation structure inside the fan blades according to claim 1, characterized in that, The fixed anchor plates (6) are symmetrically arranged on the blade web at the rear end of the main air duct, and the ropes are installed on both sides of the main air duct.

4. The heating duct installation structure inside the fan blades according to claim 1, characterized in that, The fixed anchor plate (6) includes a pulley upper limit plate (603), an anchor plate bonding base plate (604), a pulley fixing shaft (602) installed between the pulley upper limit plate and the anchor plate bonding base plate, and a pulley (601) installed on the pulley fixing shaft.

5. The heating duct installation structure inside the fan blades according to any one of claims 1-4, characterized in that, The flexible duct is made by hot-pressing and bonding of fabric.

6. The heating duct installation structure inside the fan blades according to any one of claims 1-4, characterized in that, The main duct adopts a constricted structure with a large inlet diameter at the front end and a small outlet diameter at the rear end. The sum of the cross-sectional area of ​​the rear outlet of the main duct and the cross-sectional areas of the side outlets of all branch ducts is less than the cross-sectional area of ​​the inlet of the main duct.

7. The heating duct installation structure inside the fan blades according to any one of claims 1-4, characterized in that, The front end of the main air duct is connected to the air outlet duct of the heater by means of a locking band.

8. The heating duct installation structure inside the fan blades according to any one of claims 1-4, characterized in that, A loop is provided at the rear end of the main air duct, and the rope is connected to the main air duct through the loop.

9. An installation method for a heating duct installation structure inside a fan blade as described in any one of claims 1-8, characterized in that... Includes the following steps: S1. Connect the front end of the main air duct to the air outlet duct of the heater to complete the installation of the front end of the flexible air duct; S2. Apply glue evenly to the bottom surface of the anchor plate; S3. Connect one end of the rope to the rear end of the main air duct, and pass the other end of the rope through the pulley on the fixed anchor plate and make a round trip, leaving it near the baffle. S4. First, use the robot to clamp the entire anchor plate and move it to the position on the blade web surface where it needs to be fixed. Then, the robot places the anchor plate at the fixed point and maintains the clamping force and downward pressure to prevent the anchor plate from slipping. Next, the robot's heating device heats the glue applied to the surface of the anchor plate to accelerate the curing of the glue. Finally, the glue cures between the anchor plate and the blade web, and the anchor plate installation is completed. S5. Pull the end of the rope near the baffle to move the rear end of the main air duct toward the fixed anchor plate until the main air duct is completely straightened. Then, tie the end of the rope near the baffle to a position in the blade leading edge cavity that is convenient for personnel to operate.

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