Method and system for rapidly removing frozen cover based on infrared mechanism

Abstract

The present invention relates to the field of infrared ice breaking technology for wind turbine blades, and specifically to a method and system for quickly removing a frozen covering layer based on an infrared mechanism. The specific method is as follows: S1. At least one infrared emitting device is configured at a fixed point to irradiate the leading edge of a downwardly tilted wind blade. S2. The irradiation parameters of the infrared emitting device are determined, and at least one infrared emitting device is used to emit an expanded light beam; S3. Infrared light with a rated power density is irradiated to the leading edge of the wind blade to form an interface water film between the transparent ice layer and the blade surface, thereby causing the ice layer to fall off the blade. The present application uses at least one expanded infrared light, based on infrared radiation within the rated power density range, to expand the emitted infrared light to form a large-area light spot to irradiate the blade. When the blade with ice on the surface is continuously irradiated by infrared radiation, the ice inside the ice layer that is close to the blade surface will quickly melt into an interface water film. This water film significantly reduces the friction between the blade and the ice layer.

Description

Technical Field

[0001] The present invention relates to the technical field of infrared deicing of wind turbine blades, and in particular to a method and deicing system for rapidly removing a frozen covering layer based on an infrared mechanism. Background Art

[0002] The formation of frozen cover on the surface of wind turbine blades is very easy to occur in high humidity areas. Due to weather conditions, rime, hoarfrost, mixed rime, etc. are attached, which increases the weight of the blades, changes their shape, and forms an unbalanced load, resulting in reduced wind turbine power generation and blade damage, affecting the wind turbine's power generation efficiency and service life; ice thrown when the blades rotate will also pose a safety hazard to nearby personnel. The current mainstream blade de-icing solutions in the industry are electric heating de-icing, gas heating de-icing, and coating anti-icing technology. These solutions are not mature and may cause damage to the blades, and cannot meet the requirements of use. Therefore, a de-icing method based on infrared mechanism has gradually emerged, but the following defects still exist:

[0003] First, some current infrared-based de-icing technologies use focused beams. These beams are focused to the centimeter level and are primarily designed to melt ice within the irradiated area. However, they are incapable of tackling large ice deposits and may even damage blades. Direct conversion using multiple beams requires a large number of laser beams to cover the same area, making control difficult and spot uniformity unreliable.

[0004] Second, another de-icing method based on infrared mechanism uses a light beam to scan the ice layer, breaking the ice layer to achieve ice breaking; however, in cold weather conditions, after the local area's light source is removed, the ice layer will re-freeze in a very short time, and the ice breaking effect is not ideal, so long-term exposure to the light source is required. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and de-icing system for quickly removing the frozen cover layer based on the infrared mechanism, so as to solve the problem that the frozen cover layer is prone to re-icing in traditional de-icing methods, and further solve the problems of low de-icing efficiency and light source easily causing damage to wind blades.

[0006] The technical solution of the present invention is: a method for quickly removing frozen cover based on infrared mechanism, comprising:

[0007] S1. Deploy at least one infrared emitting device at a fixed point, wherein the infrared emitting device is used to illuminate the leading edge of a downwardly tilted wind blade;

[0008] S2. Determine the irradiation parameters of the infrared emitting device based on the thickness of the frozen cover, wherein the irradiation parameters include the spot area, power density, and irradiation time; at least one of the infrared emitting devices is configured to emit an expanded light beam, and the irradiated spot area corresponding to each unit centimeter thickness of the frozen cover is not less than 0.55 m 2 ;

[0009] S3. Irradiate infrared light with rated power density to the leading edge of the wind blade, eventually forming an interfacial water film between the frozen cover layer and the surface of the wind blade. When the gravity of the frozen cover layer is greater than the sum of friction and stress, the frozen cover layer falls off the blade.

[0010] Preferably, the infrared emitting device is configured with at least two groups, including a first infrared emitting unit and a second infrared emitting unit; the first infrared emitting unit forms a first light spot area, and the second infrared emitting unit forms a second light spot area; the first light spot area and the second light spot area overlap.

[0011] Preferably, the first infrared emitting portion is used to emit an expanded light beam, and the second infrared emitting portion is used to emit a concentrated light beam.

[0012] Preferably, in step S2, a second infrared emitting unit is used to emit a focused light beam and project it onto the leading edge of the wind blade to obtain the thickness of the frozen cover layer at the corresponding position; based on the thickness of the frozen cover layer, the light spot area of ​​the first infrared emitting unit is determined, and an expanded light beam is emitted and projected onto the leading edge of the wind blade so that the first light spot area covers the second light spot area.

[0013] Preferably, the first infrared emitting portion moves along the length direction of the wind blade from the root to the tip at a rated step length;

[0014] When the first infrared emitting part continues to irradiate, the focused light beam emitted by the second infrared emitting part reciprocates in the first light spot area along a direction perpendicular to the length of the wind blade.

[0015] Preferably, in the wind blade ice-breaking area corresponding to any of the first light spot areas, the irradiation time of the second infrared emitting unit is not greater than the irradiation time of the first infrared emitting unit, and thus the second infrared emitting unit withdraws from the corresponding blade ice-breaking area earlier than the first infrared emitting unit, and advances one step from the root to the tip along the length direction of the wind blade.

[0016] Preferably, the second light spot area is located at an end of the first light spot area away from the root of the wind blade.

[0017] Preferably, the first infrared emitting portion and the second infrared emitting portion are both used to emit an expanded light beam.

[0018] Preferably, the first infrared emitting portion and the second infrared emitting portion both move alternately along the length direction of the wind blade from the root to the tip at a rated step length.

[0019] Preferably, the power density of the infrared emitting device for emitting the expanded light beam is 1 kW / m 2 ~10kW / m 2 .

[0020] Preferably, the wavelength of the light beam of the infrared emitting device used for emitting the expanded light beam is 750nm to 860nm; the wavelength of the light beam of the infrared emitting device used for emitting the concentrated light beam is 1065nm to 1940nm.

[0021] Preferably, the incident angle of the light beam emitted by the infrared emitting device is 75° to 105°.

[0022] A frozen cover removal system is used for the method of quickly removing frozen cover based on infrared mechanism.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] (1) The present application adopts at least one expanded infrared light, based on the infrared radiation within the rated power density range, to expand the emitted infrared light into a large area spot and irradiate the wind blade. When the wind blade with ice on the surface is continuously irradiated by infrared radiation, re-icing will not occur in the large area. The ice inside the ice layer close to the blade surface will quickly melt into interfacial water, forming a layer of "water film". This water film causes the friction between the blade and the ice layer to be greatly reduced. At the same time, the ice layer in the area of ​​continuous infrared radiation irradiation will also cause structural splitting due to uneven internal thermal stress. When the gravity of the ice layer is greater than the sum of the friction and other stresses, the ice layer will quickly break and fall off.

[0025] (2) Under actual environmental conditions, especially when the ice layer is thick, even if an interface water film is formed, the ice layer is not easy to break and cannot be broken off. The present application accelerates the breaking of the ice layer by combining a focused beam, thereby achieving rapid shedding of the ice layer. When the first infrared emitting unit continuously irradiates, since the area of ​​the second light spot area is small, the focused beam emitted by the second infrared emitting unit reciprocates in the first light spot area along a direction perpendicular to the length of the wind blade. At this time, due to the continuous irradiation of the first infrared emitting unit, the area traversed by the second infrared emitting unit will not re-ice after the beam is removed. At the same time, the focused beam first reaches the blade breaking area, and the ice thickness is measured based on the infrared ranging principle, which is conducive to adjusting the irradiation parameters of the expanded beam.

[0026] (3) The present application also provides a method for achieving ice breaking by combining two groups of expanded light beams. The first light spot area and the second light spot area both have a distribution of beam energy, and the overlapping part thereof can achieve energy superposition, accelerate the breaking of the ice layer, and further improve the ice breaking efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0028] Figure 1 This is a distribution diagram of the wind blades and infrared emitting devices described in Example 1 of the present invention in an actual application scenario;

[0029] Figure 2 The present invention adopts a direct power density of 1kW / m 2 When , the curve of the blade surface temperature rising over time;

[0030] Figure 3 The present invention adopts a direct power density of 5kW / m 2 When , the curve of the blade surface temperature rising over time;

[0031] Figure 4 The present invention adopts a direct power density of 10kW / m 2 When , the curve of the blade surface temperature rising over time;

[0032] Figure 5 This is a distribution diagram of the wind blades and infrared emitting devices described in Example 2 of the present invention in an actual application scenario. DETAILED DESCRIPTION

[0033] The present invention will be described in further detail below with reference to specific embodiments:

[0034] To facilitate understanding, the application scenario of this application is first explained. In high-humidity and cold areas, rime and hoarfrost phenomena, or mixed rime phenomena composed of these, are very likely to occur, which are collectively referred to as frozen cover; among them, rime is a glass-like transparent or matte ice cover formed on the surface of an object; hoarfrost is a milky white ice crystal deposit formed when water vapor in the air directly condenses or supercooled fog droplets directly freeze on an object. This application is used to remove the frozen cover on the blades of wind turbines to avoid increasing the weight of the blades, changing their shape, and forming an unbalanced load, thereby avoiding safety hazards.

[0035] Example 1

[0036] This application provides a method for quickly removing frozen cover based on infrared mechanism, which is mainly as follows:

[0037] The first step is to configure the infrared transmitter;

[0038] like Figure 1 As shown, two infrared emitting devices are fixedly arranged near the wind blades 100 of the wind turbine generator set, including a first infrared emitting unit 200 and a second infrared emitting unit 300; the first infrared emitting unit 200 is used to emit an expanded light beam, and the second infrared emitting unit 300 is used to emit a concentrated light beam.

[0039] Due to the collision of supercooled water droplets and the influence of airflow in cold weather, the windward side of the leading edge of the running wind turbine blades is more prone to ice formation and the frozen cover is thicker. When the ambient temperature is below 0°C, the supercooled water droplets in the air collide with the surface of the wind turbine blades, causing the internal balance of the supercooled water droplets to be destroyed, the freezing temperature to increase, and condensation into ice on the surface of the blades. The windward side of the leading edge of the wind turbine blade is more likely to collide with supercooled water droplets, so the ice formation in this area is more serious. At the same time, the windward side directly faces the airflow, and the supercooled water droplets in the airflow are more likely to be carried to the windward side of the blade and attached to ice. On the leeward side, due to the relatively stable airflow, there are fewer opportunities for contact with water droplets, and the amount of ice coverage is relatively small. Therefore, combined with Figure 1 As shown, two infrared emitting devices are used to illuminate the leading edge of a wind blade that is tilted downward in a stationary state. The incident angle α of the light beam emitted by the infrared emitting device is 75° to 105°, and the incident angle is defined as the angle between the center line of the light beam and the length direction of the wind blade.

[0040] The second step is to determine the irradiation parameters of the infrared emitting device;

[0041] In this embodiment, the first infrared emitting unit is used to irradiate the wind blade to form a first light spot area, and the second infrared emitting unit is used to irradiate the wind blade to form a second light spot area; in the deicing scenario, the first light spot area and the second light spot area will overlap after being irradiated on the wind blade.

[0042] a. During the de-icing process, regarding the wavelength of the infrared emission device's beam:

[0043] The wavelength of the beam of the first infrared emitting unit 200 for emitting the expanded light beam is 750nm~860nm. In order to ensure that the infrared light can effectively penetrate clouds and ice and be absorbed by the target surface medium, the infrared light needs to meet the following conditions during design: First, cloud and fog penetration ability: infrared rays have a strong ability to penetrate clouds and fog, and can maintain good transmission effects under severe weather conditions; second, ice penetration ability: select infrared light with shorter wavelengths and higher energy, which can more effectively penetrate the ice layer and achieve penetration of deep ice layers; third, ice absorption characteristics: ice has a high absorption rate for infrared rays, which helps to improve heating efficiency; fourth, surface medium absorption: most surface media have good absorption properties for infrared radiation, which helps to improve the heating effect.

[0044] The wavelength of the light beam of the second infrared emitting unit 300 for emitting a focused light beam is 1065nm~1940nm. In this embodiment, the focused light beam needs to meet the following requirements: a. Realize the measurement of the thickness of the frozen cover layer, based on the time difference between the emission and reflection reception of the infrared focused light beam, to calculate the thickness of the frozen cover layer; b. Accelerate the fracture of the ice layer, still based on the absorption rate of the ice layer to infrared light, so that the area irradiated by the second infrared emitting unit can accelerate melting and fracture.

[0045] b. The spot area of ​​the expanded light beam emitted by the first infrared emitting unit 200;

[0046] In this embodiment, the spot area is positively correlated with the thickness of the frozen cover layer, and the irradiated spot area corresponding to each unit centimeter thickness of the frozen cover layer is not less than 0.55m 2 .

[0047] Specifically, according to the blade ice shear strength of 0.5MPa, the ice density is 900kg / m 3 When the ice is 1cm thick, the ice layer can withstand a shear force of no more than 50N, that is, 5kg of ice is equivalent to about 0.55m 2 ice-covered area.

[0048] To ensure that there is a sufficient spot area on the frozen cover, in this embodiment, the infrared light emitted by the infrared emitting device is transmitted through an optical fiber and is homogenized, shaped, and expanded by optical devices. The homogenization and shaping are intended to make the irradiation power distribution within the spot more uniform, reduce the control difficulty, and increase the controllability of the system. The purpose of expanding the beam is to make the area of ​​the spot larger so that it can cope with a frozen cover over a larger range. This is completely different from the traditional focused deicing technology, which focuses the light beam to the centimeter level and achieves complete melting of the ice layer in the irradiated area.

[0049] c. Power density of the expanded light beam emitted by the first infrared emitting unit 200:

[0050] In order to form an interface water film between the transparent ice layer and the wind blade, the interface heating rate needs to be greater than the heat diffusion rate. The simulation test was conducted at an ambient temperature of -20℃, when the power density was less than 1kW / m 2 The interface heating rate is lower than the heat diffusion rate, making it difficult to form a water film on the ice-covered interface. In the simulation test, when the ambient temperature is -10℃ and the power density is higher than 10kW / m 2 , reaching the maximum temperature of the blade for safe operation. Therefore, in this application, the power density is set to 1kW / m 2 ~10kW / m 2 .

[0051] Theoretically, when the power density meets the minimum requirements and the energy consumption of the infrared emitting device is not considered, the higher the power density, the better the de-icing effect. However, in this application, the infrared light irradiated by the first infrared emitting unit forms a large-area light spot after expansion, and the ice layer on the surface of the wind blade is not fully covered, it may be local or intermittent on the wind blade. Therefore, when the infrared light is irradiated on the wind blade, there are local light spots irradiated on the frozen cover layer, and local light spots irradiated on the blade; when the infrared light is directly irradiated on the wind blade, it is necessary to control the heating temperature of the wind blade to avoid damage to the wind blade, so it is necessary to control the power density, that is, the power density is not the larger the better.

[0052] In actual application scenarios, external environmental conditions, such as wind speed, will also affect the surface temperature of wind blades. Since wind speed will accelerate convection and slow down the temperature rise of the blade surface, the upper limit of power density needs to be considered in combination with wind speed.

[0053] The blade slice sample was placed in a low temperature box set at a constant temperature of -10℃, and an air flow of about 3m / s was generated on the blade surface. 2 5kW / m 2 、10kW / m 2 The blade is irradiated with infrared radiation and the maximum temperature of the irradiated surface is measured using an infrared thermometer.

[0054] Combine Figure 2 、 Figure 3 、 Figure 4 As shown in the figure, as time goes by, the surface temperature of the wind blade gradually rises. When the ambient temperature is -10℃ and the direct power density is 10kW / m 2 , under the wind speed of less than 3m / s, the maximum temperature of the wind blade surface reaches 70℃ within 5 minutes of continuous irradiation, which is the maximum safe working temperature of the wind blade. 2 ~10kW / m 2 Within the range, the continuous irradiation time is set to less than 5 minutes to avoid damage to the leaves. At the same time, work efficiency must be guaranteed and the continuous irradiation time cannot be too long.

[0055] d. Regarding the spot area and power density of the concentrated light beam emitted by the second infrared emitting unit:

[0056] Since the focused beam emitted by the second infrared emitting unit is used to measure the thickness of the frozen cover and accelerate the fracture of the ice layer, the centimeter-level spot area is generally controlled at 5 to 25 cm. 2 The focused beam is used to overlap the energy with the expanded beam, so the power density can be controlled at 1kW / m 2 ~10kW / m2 within the range.

[0057] e. Regarding the irradiation time of the infrared emitting device;

[0058] Refer to the above slice experiment and combine it with the attached Figure 4 It can be seen that at an ambient temperature of -10°C and a direct power density of 10kW / m 2 When the wind speed is lower than 3m / s, the maximum temperature of the wind blade surface reaches 70°C within 5 minutes of continuous irradiation. After that, if the irradiation time exceeds 5 minutes, the temperature of the wind blade surface will continue to rise. Therefore, the irradiation time of the infrared emitting device is set to no more than 5 minutes in this application.

[0059] In summary, the spot area, power density and irradiation time will directly affect the removal efficiency of the frozen cover. In this embodiment, the power density and irradiation time are set to fixed values, for example: the power density is 6kW / m 2 , the irradiation time is 3 minutes; based on the thickness of the frozen cover layer obtained, the size of the light spot area is adjusted. The light spot area is positively correlated with the thickness of the frozen cover layer, and a mapping relationship is established between the two, thereby ensuring that under constant power density and irradiation time, the removal of frozen covers of different thicknesses is achieved by adjusting the size of the light spot area. It should also be noted that since the subsequent first light spot area and the second light spot area need to effectively overlap and need to move at a rated step length, in this embodiment, the first infrared emitting unit is used to emit a rectangular light beam, which has a "length" set along the length direction of the wind blade and a "width" perpendicular to the length direction of the wind blade. The first light spot area always moves along the "length" direction at a rated step length, and thus when the light spot area is adjusted, the width of the first light spot area can be directly adjusted.

[0060] The third step is to turn on the infrared emitting device for irradiation;

[0061] Infrared light with rated power density is irradiated onto the wind blade and moves along a preset trajectory; eventually, an interfacial water film is formed between the frozen cover and the surface of the wind blade. When the gravity of the frozen cover is greater than the sum of friction and stress, the frozen cover falls off the blade.

[0062] Specifically, during initial irradiation, the second infrared emitting unit emits a focused beam onto the leading edge of the wind blade near the root. The thickness of the frozen cover at the location corresponding to the focused beam is determined. Based on the frozen cover thickness, the spot area of ​​the first infrared emitting unit is determined, and an expanded beam is emitted onto the leading edge of the wind blade, so that the first spot area overlaps the second spot area. When the first and second spot areas overlap, the second spot area is positioned at the end of the first spot area away from the wind blade root. In deicing scenarios, the wind blade illuminated by the infrared emitting device tilts downward. The water film formed by the continuous irradiation of the first spot area and the ice fracture caused by the overlapping irradiation of the first and second spot areas accelerate the shedding of the tilted ice. Since the second spot area is positioned at the end of the first spot area away from the wind blade root, the ice fracture is minimized below the first spot area, resulting in a more extensive ice shedding process.

[0063] Since the first infrared emitting unit and the second infrared emitting unit are initially irradiated at the root of the blade, the subsequent specific movement trajectory is:

[0064] The first infrared emitting unit moves along the length of the wind blade from root to tip at a rated step length. While the first infrared emitting unit continues to illuminate, the focused light beam emitted by the second infrared emitting unit reciprocates perpendicularly to the length of the wind blade within the first light spot area. Within the ice-breaking area of ​​the wind blade corresponding to any first light spot area, the illumination duration of the second infrared emitting unit is no longer than that of the first infrared emitting unit. Consequently, the second infrared emitting unit withdraws from the corresponding ice-breaking area earlier than the first infrared emitting unit and advances one step length from root to tip along the length of the wind blade, thereby pre-determining the thickness of the ice layer in the next ice-breaking area to be broken.

[0065] In actual wind power generation scenarios, wind blades face complex and changing environmental conditions, and the presence of frozen cover layers presents diverse forms. First, the thickness distribution of the frozen cover layer does not follow a simple rule of gradually increasing thickening from the root to the tip of the blade. In an ideal theoretical model, it is assumed that the thickness of the ice layer gradually increases as the blade extends from the root to the tip. However, in reality, due to the combined influence of multiple factors such as wind force, humidity, and temperature, the distribution of ice thickness is irregular. Second, the coverage of the frozen cover layer is not completely continuous. In actual observation, it is often seen that the ice layer on the blade surface presents discontinuous distribution forms such as patches and stripes. In addition, factors such as the material and roughness of the blade surface will also affect the adhesion and distribution of the ice layer, making the ice layer on the blade surface uneven.

[0066] When the second infrared emitting unit emits a focused beam onto the frozen cover, due to the diversity of the frozen cover, the focused beam may directly illuminate the wind turbine blades that are not covered with frozen cover. In this case, the thickness of the frozen cover cannot be obtained. Therefore, the first infrared emitting device is set to emit a minimum spot area (0.55m 2 ) is directed onto the wind blade, while the second infrared emitting device is turned off. By emitting an expanded beam with a minimal spot area, a wider range of wind blade surfaces can be detected and heated without wasting excessive energy.

[0067] During the above operation process, since the first infrared emitting unit emits an expanded light beam, a large-area light spot is formed to illuminate the wind blade. When the wind blade with ice on the surface is continuously irradiated by infrared radiation, re-icing will not occur in a large area, and the ice inside the ice layer close to the blade surface will quickly melt into interfacial water, forming a layer of "water film"; the laser beam emitted by the second infrared emitting unit reciprocates in the first light spot area in a direction perpendicular to the length of the wind blade. At this time, due to the continuous irradiation of the first infrared emitting unit, the area traversed by the second infrared emitting unit will not re-icing after the light beam is removed.

[0068] Example 2

[0069] The first step is to configure the infrared transmitter;

[0070] like Figure 5 As shown, two infrared emitting devices, comprising a first infrared emitting unit 200 and a second infrared emitting unit 300, are positioned near wind blades 100 of a wind turbine generator set. Both the first infrared emitting unit 200 and the second infrared emitting unit 300 are configured to emit an expanded light beam. In this embodiment, the two infrared emitting devices are still configured to illuminate the leading edge of the downwardly tilted wind blades, with the incident angle α of the emitted light beams from the infrared emitting devices ranging from 75° to 105°.

[0071] The second step is to determine the irradiation parameters of the infrared emitting device;

[0072] In this embodiment, since the first infrared emitting unit 200 and the second infrared emitting unit 300 are both used to emit an expanded light beam, they can be defined to have the same irradiation parameters.

[0073] The wavelength of the light beams of the first infrared emitting part and the second infrared emitting part is 750nm to 860nm;

[0074] The power density of the first infrared emitting part and the second infrared emitting part is 1kW / m 2 ~10kW / m 2 ;

[0075] The spot area of ​​the first infrared emitting part and the second infrared emitting part is not less than 0.55m 2 ;

[0076] The continuous irradiation time of the first infrared emitting part and the second infrared emitting part is 3 minutes.

[0077] The third step is to turn on the infrared emitting device for irradiation;

[0078] Infrared light with a rated power density is directed onto a wind turbine blade, moving it along a predetermined trajectory. This ultimately forms an interfacial water film between the frozen cover and the blade surface. When the weight of the frozen cover exceeds the combined friction and stress, the frozen cover falls from the blade. In this embodiment, both the first and second infrared emitting units move alternately along the length of the wind turbine blade, from root to tip, at a rated step length. The overlap between the first and second light spot areas accelerates the breaking of the ice layer, thereby accelerating the shedding of tilted ice.

[0079] Specifically, first, the first infrared emitting unit emits an expanded light beam to irradiate the root of the wind blade, forming a first light spot area at the leading edge of the wind blade. Compared with the first emitting unit, the second emitting unit moves a rated length L from the blade root to the blade tip and emits an expanded light beam, thereby forming a second light spot area at the leading edge of the wind blade, and there must be overlap between the first light spot area and the second light spot area; after the first infrared emitting unit irradiates for 3 minutes, the first infrared emitting unit moves from the blade root to the blade tip according to the rated step length of 2L and continues to irradiate; after the second infrared emitting unit irradiates for 3 minutes, the second infrared emitting unit moves from the blade root to the blade tip according to the rated step length of 2L, and repeats this cycle, so that the first infrared emitting unit and the second infrared emitting unit move alternately according to the rated step length.

[0080] In this embodiment, the first infrared emitting unit and the second infrared emitting unit are not used to obtain the thickness of the ice layer, but are only used to provide infrared radiation for continuous irradiation. The thickness of the frozen cover layer can be measured based on the infrared focused beam reflection method and the infrared thermal imaging method. In this embodiment, the thickness of the frozen cover layer is only obtained once, and the acquisition position must be close to the tip of the blade. Based on the obtained thickness of the frozen cover layer, after the spot area is determined, the first infrared emitting unit and the second infrared emitting unit are subsequently alternately moved, and the spot area is always constant. For example, the spot area is defined as 0.6m 2 .

[0081] Under environmental conditions, there are two situations: one is that the frozen covering layer on the surface of the wind blade is a rime covering layer; the other is that the frozen covering layer on the surface of the wind blade is a rime covering layer, or a mixed rime covering layer.

[0082] a. When the frozen cover layer on the surface of the wind turbine blade is rime, since the rime cover layer itself is transparent, infrared light can penetrate the transparent ice layer. By controlling the continuous irradiation time in the fixed spot area to less than 5 minutes, an interface water film is formed in the corresponding area.

[0083] Since the blades of wind turbines are long, the light spot needs to move along the wind blades. Under environmental conditions where a rime cover can be formed, the rotation speed at the blade root is low and convection is relatively small, so there is relatively less ice at the blade root. However, fifty or sixty meters away from the blade root, near the blade tip, there will be a lot of convection and the water cannot be thrown off. Therefore, there is more ice near the blade tip. Furthermore, in order to remove the rime cover on the blade, when the formed light spot moves along the length of the blade, the irradiation time from the blade root to the blade tip can also be increased under constant power density.

[0084] At the same time, there will be bubbles and impurities in the transparent ice layer. The impact of bubbles and impurities on light is mainly reflected in their scattering, refraction and reflection. These effects can change the propagation direction and intensity of light. Therefore, in actual scenarios, the power density is controlled at 5kW / m 2 ~7kW / m 2 .

[0085] b. When the frozen cover on the blade surface is rime or mixed rime, the rime is a milky white ice crystal deposit, so its infrared light penetration ability is relatively weak. However, since the formation of rime is a process in which water vapor molecules gradually accumulate and crystallize on the surface of an object, its structure is relatively loose and the connection between ice crystals is not tight enough. Compared with rime, rime has weaker adhesion to the surface of wind turbine blades, so the power density is controlled at 5kW / m 2 ~7kW / m 2 The rime covering layer or the mixed rime covering layer can also be removed.

[0086] The present application also discloses a frozen cover removal system for performing a method for rapidly removing frozen cover based on an infrared mechanism.

[0087] By combining the system and method, the first infrared emitting unit expands a single beam of infrared light to form a large-area light spot. By controlling the power density range, it achieves large-scale rapid de-icing of wind turbine blades. Because the de-icing method is "partial melting," the energy consumption required for de-icing is greatly reduced. Combined with the second infrared emitting unit, especially for thicker frozen cover, because both the first and second light spot areas have beam energy distributions, the overlapping areas can achieve energy superposition, accelerating the fracture of the frozen cover and, in turn, the shedding of the ice layer, making de-icing more efficient.

[0088] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they are not intended to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

Claims

1. A method for rapidly removing frozen cover based on infrared mechanism, characterized in that: Here’s how: S1. Deploy at least one infrared emitting device at a fixed point, wherein the infrared emitting device is used to illuminate the leading edge of a downwardly tilted wind blade; S2. Determine the irradiation parameters of the infrared emitting device based on the thickness of the frozen cover, wherein the irradiation parameters include the spot area, power density, and irradiation time; at least one of the infrared emitting devices is configured to emit an expanded light beam, and the irradiated spot area corresponding to each unit centimeter thickness of the frozen cover is not less than 0.55 m 2 ; S3, irradiating the leading edge of the wind blade with infrared light having a rated power density, eventually forming an interfacial water film between the frozen cover layer and the surface of the wind blade, and when the gravity of the frozen cover layer is greater than the sum of the friction force and the stress, the frozen cover layer falls off the blade; The infrared emitting device is configured with at least two groups, including a first infrared emitting portion and a second infrared emitting portion; the first infrared emitting portion forms a first light spot area, and the second infrared emitting portion forms a second light spot area; the first light spot area and the second light spot area overlap; The second infrared emitting unit emits a focused beam and projects it onto the leading edge of the wind blade to obtain the thickness of the frozen cover at the corresponding location. Based on the thickness of the frozen cover, the spot area of ​​the first infrared emitting unit is determined, and an expanded beam is emitted and projected onto the leading edge of the wind blade so that the first spot area covers the second spot area. The first infrared emitting portion moves along the length direction of the wind blade from the root to the tip at a rated step length; when the first infrared emitting portion continues to irradiate, the focused light beam emitted by the second infrared emitting portion reciprocates in the first light spot area along the direction perpendicular to the length direction of the wind blade; In the wind blade ice-breaking area corresponding to any first light spot area, the irradiation time of the second infrared emitting unit is not greater than the irradiation time of the first infrared emitting unit, so that the second infrared emitting unit withdraws from the corresponding blade ice-breaking area earlier than the first infrared emitting unit, and moves one step ahead from the root to the tip along the length direction of the wind blade.

2. The method for rapidly removing frozen cover layers based on infrared mechanism according to claim 1, characterized in that: The first infrared emitting portion is used to emit an expanded light beam, and the second infrared emitting portion is used to emit a concentrated light beam.

3. The method for rapidly removing frozen cover layers based on infrared mechanism according to claim 1, characterized in that: The second light spot area is located at an end of the first light spot area away from the root of the wind blade.

4. The method for rapidly removing frozen cover layers based on infrared mechanism according to claim 1, characterized in that: The first infrared emitting portion and the second infrared emitting portion are both used for emitting an expanded light beam.

5. The method for rapidly removing frozen cover layers based on infrared mechanism according to claim 4, characterized in that: The first infrared emitting portion and the second infrared emitting portion both move alternately along the length direction of the wind blade from the root to the tip at a rated step length.

6. The method for rapidly removing frozen cover layers based on infrared mechanism according to claim 2 or 4, characterized in that: The power density of the infrared emitting device for emitting the expanded light beam is 1kW / m 2 ~10kW / m 2 .

7. The method for rapidly removing frozen cover layers based on infrared mechanism according to claim 2, characterized in that: The wavelength of the light beam of the infrared emitting device used for emitting the expanded light beam is 750nm~860nm; the wavelength of the light beam of the infrared emitting device used for emitting the concentrated light beam is 1065nm~1940nm.

8. The method for rapidly removing frozen cover based on infrared mechanism according to claim 1, characterized in that: The incident angle of the light beam emitted by the infrared emitting device is 75° to 105°.

9. A frozen cover removal system, characterized in that: Used to implement a method for quickly removing frozen covering layers based on infrared mechanism as described in any one of claims 1-5 or 7-8.

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