Anti-icing and wind-blown sand resisting multi-stage micro-nano structure coated on the front edge of a rotor blade and a preparation method thereof

Abstract

The application provides a multi-stage micro-nano structure package for preventing and removing ice and resisting wind sand on a front edge of a rotor, which comprises a rotor shell and a composite heat-conducting rubber located on the front edge of the rotor shell outside, the surface of the composite heat-conducting rubber is provided with a multi-stage micro-nano structure in which micro convexes and micro concaves are alternately arranged, and the inside of the composite heat-conducting rubber is provided with carbon fiber wires for conducting electricity and generating heat; wherein the multi-stage micro-nano structure is provided with micro convexes and micro concaves, and the edges of the two sides are provided with ladder-shaped asymmetric structures in a strip shape; the multi-stage micro-nano structure and the ladder-shaped asymmetric structures of the composite heat-conducting rubber can reduce the condensation degree of water drops on the surface of the machine body, make the water drops formed by the melting of the ice layer on the surface of the machine body separate from the machine body as soon as possible, be beneficial to the falling of the ice layer which has been formed, delay the icing of the rotor, and further prevent re-icing; the carbon fiber wires in the inside of the composite heat-conducting rubber have good electric heating performance, can convert electric energy into heat energy, and effectively prevent and remove ice.

Description

Technical Field

[0001] This invention belongs to the field of rotor leading edge protection technology, specifically relating to a multi-level micro-nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor and its preparation method. Background Technology

[0002] Due to their speed and safety, airplanes have gradually become an increasingly important means of transportation. Research on aircraft icing and its protection technology is an important aspect that cannot be ignored in the development of airplanes, especially large transport aircraft. When airplanes take off, land, or fly in sandy areas, loose sand particles in the ground and air will impact the surface of the airplane. Larger sand particles can damage the rotor blades. When airplanes fly in high-altitude, frigid areas, cold water droplets in the atmosphere will quickly accumulate on the leading edge of the high-speed rotating rotor blades and then condense into ice. Icing on the leading edge of the rotor blades will cause distortion of the intake airflow field, which will lead to the deterioration of the aerodynamic qualities of the airplane, such as handling and stability (especially in the case of aero engines, where the intake fairing and support plates are prone to icing under certain temperature and humidity conditions on the ground and in the air). The detached ice may also cause engine blades to break, or even lead to major accidents such as the destruction of the aircraft and loss of life.

[0003] Current de-icing methods include pneumatic belt de-icing, liquid anti-icing, and electrothermal de-icing. Pneumatic belt de-icing utilizes the expansion of expansion tubes on the leading edge of aircraft components to break and remove the ice layer, typically used on the leading edges of rotors and tail rotors. Liquid anti-icing primarily uses liquid alcohol as an antifreeze to prevent rotor blade icing. This was the most common de-icing technology for early helicopters in my country. The antifreeze is a chemical solution composed of ethylene glycol and water in a certain proportion. Ethylene glycol has a lower freezing point than water; when it mixes with water droplets on the rotor surface, the mixture's freezing point is lower than the rotor surface temperature, thus preventing icing. Electrothermal de-icing converts electrical energy into heat energy for melting and de-icing. It generally uses either continuous or intermittent heating. Helicopter rotor heating consumes a lot of electricity; therefore, for energy conservation, intermittent heating is used for de-icing. In addition to the above-mentioned anti-icing and de-icing methods, installing low surface energy hydrophobic components on the icing-prone parts of the aircraft can also play a passive anti-icing and de-icing role. Therefore, this application proposes a multi-level micro-nano structure packing for the leading edge of an anti-icing, de-icing, and sand-resistant rotor and its preparation method. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes a multi-level micro-nano structure covering for the leading edge of a de-icing and anti-sand-wind rotor and its preparation method. The purpose is to effectively prevent sand and wind erosion of the aircraft surface, reduce the formation of ice on the leading edge of the rotor, and help reduce the cost and energy consumption of aircraft de-icing.

[0005] The technical solution adopted by the present invention for a multi-level micro-nano structure cladding at the leading edge of an anti-icing and anti-sandstorm rotor is as follows: it includes a rotor shell and a composite thermally conductive rubber located at the outer leading edge of the rotor shell. The surface of the composite thermally conductive rubber has a multi-level micro-nano structure with alternating micro-protrusions and micro-pits, and the interior has conductive and heat-generating carbon fiber filaments. The multi-level micro-nano structure is made of the composite thermally conductive rubber using a stainless steel mesh and a mold.

[0006] Specifically, the outer leading edge of the rotor casing refers to the rotor root portion projected onto the first fifth of the chord length;

[0007] Beneficial effects: The rubber cladding installed on the leading edge of the rotor has high elasticity and wear resistance, which can effectively resist wind and sand erosion of the aircraft surface.

[0008] Specifically, the multi-level micro-nano structures are micrometer-sized, crisscrossed, and interconnected, forming a large number of air pockets. The two sides of the multi-level micro-nano structures have a stepped asymmetric structure distributed in a long strip.

[0009] Beneficial effects: The multi-level micro-nano structure and stepped asymmetric structure of the composite thermally conductive rubber can reduce the degree of water droplet condensation on the surface of the aircraft, allowing water droplets formed by the melting of ice on the surface of the aircraft to detach from the aircraft as soon as possible, which is conducive to the shedding of the already formed ice layer, delays rotor icing, and thus prevents re-icing.

[0010] Specifically, each bundle of carbon fiber filaments is 3K;

[0011] Beneficial effects: The carbon fiber filaments inside the composite thermally conductive rubber have good electrical and thermal conductivity, which can convert electrical energy into heat energy and effectively prevent and de-ic. In addition, the carbon fiber filaments have excellent superconducting and mechanical properties, which helps to reduce the energy consumption of the aircraft and improve the tensile and tear resistance of the rotor leading edge shroud, thus extending the service life of the rotor leading edge shroud.

[0012] The method for preparing a multi-level micro / nano structure flap at the leading edge of an anti-icing, de-icing, and wind-blown sand rotor according to the present invention is as follows:

[0013] (1) Prepare composite rubber using conventional dry rubber mixing process: Start the mixer, heat the two rollers of the mixer to 20°C, add the raw silicone rubber into the mixer and mix for 10-15 minutes; add the pre-weighed sulfur, vulcanization accelerator, coupling agent, vulcanization activator and conductive modifier into the mixer, continue mixing for 15-20 minutes after feeding to exhaust the gas, then take out the composite rubber obtained by roller mixing and turn off the mixer;

[0014] (2) Arrange the carbon fiber filaments in an “S” shape on the surface of the composite rubber, and then press another piece of composite rubber on top of it to obtain a sheet-like compound.

[0015] (3) Take out the preheated vulcanizing mold and stainless steel pressure mesh. First, lay the sheet compound flat in the mold, then place the stainless steel pressure mesh on the surface of the sheet compound. After laying it flat, press the upper and lower molds together and put them back into the flat vulcanizing machine for vulcanization.

[0016] (4) After the set vulcanization time is reached, the mold in the vulcanizing machine is taken out. After the mold is opened, a sheet vulcanized rubber is obtained. This sheet vulcanized rubber is a composite thermally conductive rubber.

[0017] (5) Adhere the composite thermally conductive rubber to the outer leading edge of the rotor shell.

[0018] Specifically, the composite thermally conductive rubber sheet in step (1) includes the following components by weight: 100 parts of raw silicone rubber, 3 parts of sulfur, 2 parts of carbon fiber filament, 0.1 parts of coupling agent, 2 parts of vulcanization accelerator, 9 parts of vulcanization activator, and conductive modifier, wherein the conductive modifier includes 1-5 parts of carbon nanotubes and 7.5-15 parts of copper powder, and the weight ratio of carbon nanotubes to copper powder is 1:3;

[0019] Specifically, in step (3), the mold preheating temperature is 175℃ and the preheating time is 5min-8min;

[0020] Specifically, in step (1), the roller gap during the feeding process is 1mm, and the roller gap during the degassing and sheeting process is 1mm-1.5mm.

[0021] Specifically, in step (4), the vulcanization temperature is 175°C, the pressure is 70 MPa, and the time is 10 min to 15 min.

[0022] Beneficial effects: The composite thermally conductive rubber of this invention has the characteristics of low preparation cost and low energy consumption, and is an important auxiliary means for anti-icing, de-icing and sandstorm resistance on aircraft surfaces. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the rotor leading edge shroud of the present invention;

[0024] Figure 2 This is a schematic diagram of the multi-level micro / nano structure on the surface of the composite thermally conductive rubber of the present invention;

[0025] Figure 3 This is a schematic diagram of the stepped asymmetric structure of the composite thermally conductive rubber of the present invention;

[0026] Figure 4 This is a cross-sectional view of the stepped asymmetric structure of the composite thermally conductive rubber of the present invention;

[0027] Figure 5 The image shows the icing test results of the multi-level micro / nano structure and the stepped asymmetric structure of this invention.

[0028] In the diagram: 1-rotor shell, 2-composite thermally conductive rubber, 3-carbon fiber filament. Detailed Implementation

[0029] To better understand the content of this invention, the invention will be further described below with reference to specific embodiments and accompanying drawings. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps, but the scope of protection of this invention is not limited to the following embodiments.

[0030] Please see Figure 1-4 This invention discloses a multi-level micro / nano structure cladding for the leading edge of an anti-icing and anti-sandstorm rotor, comprising a rotor shell 1 and a composite thermally conductive rubber 2 (i.e., a rubber cladding) located at the outer leading edge of the rotor shell. The outer leading edge of the rotor shell refers to the rotor root within the first fifth of the chord length. The surface of the composite thermally conductive rubber 2 has a multi-level micro / nano structure with alternating micro-protrusions and micro-dimples, and contains conductive and heat-generating carbon fiber filaments 3, each bundle being 3K. The multi-level micro / nano structure is micrometer-sized, crisscrossed, and interconnected, forming numerous cavitation spaces. The two sides of the multi-level micro / nano structure have a stepped asymmetric structure distributed in elongated strips. The rubber cladding in this invention is a superhydrophobic composite thermally conductive rubber with high elasticity and wear resistance. The rubber cladding uses stainless steel mesh to obtain a superhydrophobic surface with a special structure (i.e., a multi-level micro / nano structure), which can improve anti-icing properties while effectively resisting sandstorm erosion of the aircraft surface. Please refer to [link to relevant documentation]. Figure 5 , Figure 5 The figures show the icing test results of the multi-level micro / nano structure and the stepped asymmetric structure of this invention. As can be seen from the figures, the complete icing time of the untreated rubber sheet is 132s, the complete icing time of the rubber sheet with the multi-level micro / nano structure is 236s, and the complete icing time of the rubber sheet with the stepped asymmetric structure is 220s. Therefore, the superhydrophobic multi-level micro / nano structure and the stepped asymmetric structure can delay icing and have a significant anti-icing and de-icing effect.

[0031] The superhydrophobic composite thermally conductive rubber sheath of the present invention comprises the following components in parts by weight (in units of 1 part by weight): 100 parts of raw silicone rubber, 3 parts of sulfur, 2 parts of carbon fiber filaments, 0.1 parts of coupling agent, 2 parts of vulcanization accelerator, 9 parts of vulcanization activator, and a conductive modifier, wherein the conductive modifier comprises 1-5 parts of carbon nanotubes and 7.5-15 parts of copper powder, wherein the weight ratio of carbon nanotubes to copper powder is 1:3; the preparation method of the multi-level micro-nano structure sheath of the leading edge of an anti-icing, de-icing, and anti-sandstorm rotor of the present invention is as follows:

[0032] (1) Prepare composite rubber using conventional dry rubber mixing process: Start the mixer and heat the two rollers of the mixer to 20°C. Add the raw silicone rubber to the mixer and mix for 10-15 minutes. Add the pre-weighed sulfur, vulcanization accelerator, coupling agent, vulcanization activator and conductive modifier to the mixer. The roller gap during the mixing process is 1 mm. Continue mixing the rubber during the feeding process to make it more uniform. After the feeding is completed, mix for 15-20 minutes to exhaust the air. The roller gap of the exhaust sheet is 1 mm-1.5 mm. Then take out the compound rubber obtained by mixing and turn off the mixer.

[0033] (2) Arrange the carbon fiber filaments in an “S” shape on the surface of the composite rubber, and then press another piece of composite rubber on top of it to obtain a sheet-like compound.

[0034] (3) Take out the preheated vulcanizing mold and stainless steel pressure mesh. First, lay the sheet compound flat in the mold, then place the stainless steel pressure mesh on the surface of the sheet compound. After laying it flat, press the upper and lower molds together and put them back into the flat vulcanizing machine for vulcanization. Before preheating the mold, clean it with alcohol, then rinse it with deionized water, and then preheat it. The preheating temperature is 175℃ and the preheating time is 5min-8min.

[0035] (4) The temperature of the vulcanization process is 175℃ and the pressure is 70MPa. After the set vulcanization time of 10min-15min is reached, the mold in the vulcanizing machine is taken out. After the mold is opened, sheet vulcanized rubber is obtained. This sheet vulcanized rubber is a composite thermally conductive rubber.

[0036] (5) Adhere the composite thermally conductive rubber to the outer leading edge of the rotor shell. The specific process is as follows: First, rinse with warm water to remove impurities from the rotor shell. Then, use a clean cloth to wipe the rotor surface with alcohol and dry it. The treated rotor surface should be clean and free of contamination to ensure good adhesion between the composite thermally conductive rubber and the rotor.

[0037] The rubber sheath of this invention has a stepped asymmetric structure and a multi-level micro-nano structure with superhydrophobic properties, which can reduce the degree of water droplet condensation on the aircraft surface, allowing water droplets formed by melting ice on the aircraft surface to detach from the aircraft as quickly as possible, which is beneficial to the shedding of existing ice layers and delays rotor icing. The rubber sheath contains carbon fiber filaments with good thermal conductivity, which can convert electrical energy into heat energy, thereby effectively preventing re-icing. Moreover, the carbon fiber filaments have excellent superconducting and mechanical properties, which helps to reduce the aircraft's energy consumption and improve the tensile and tear resistance of the rotor leading edge sheath, extending the service life of the rotor leading edge sheath. In addition, the rubber sheath installed on the rotor leading edge has high elasticity and wear resistance, which can effectively resist wind and sand erosion of the aircraft surface.

[0038] This invention can have other embodiments based on the above preparation method, which will not be listed one by one. Therefore, any simple modifications, equivalent changes and alterations made by any person skilled in the art to the above embodiments without departing from the scope of the technical solution of this invention shall still fall within the scope of the technical solution of this invention.

Claims

1. A multi-level micro / nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor, characterized in that, The device includes a rotor shell (1) and a composite thermally conductive rubber (2) located at the outer leading edge of the rotor shell. The surface of the composite thermally conductive rubber (2) has a multi-level micro-nano structure with alternating micro-protrusions and micro-pits. The interior of the composite thermally conductive rubber has conductive and heat-generating carbon fiber filaments (3). The multi-level micro-nano structure is made of the composite thermally conductive rubber (2) using a stainless steel mesh and a mold. The size of the multi-level micro-nano structure is at the micrometer level. The structures are interwoven and interconnected, forming a large number of air pockets. The two sides of the multi-level micro-nano structure have a stepped asymmetric structure with long strips distributed on both sides. The method for preparing the multi-level micro / nano structure flap at the leading edge of the anti-icing, de-icing, and anti-sandstorm rotor includes: Step (1) Prepare composite rubber using conventional dry rubber mixing process: Start the mixer, heat the two rollers of the mixer to 20°C, add the raw silicone rubber to the mixer and mix for 10-15 minutes; add the pre-weighed sulfur, vulcanization accelerator, coupling agent, vulcanization activator and conductive modifier to the mixer, continue mixing for 15-20 minutes after feeding to exhaust the air, then take out the composite rubber obtained by mixing and turn off the mixer; Step (2) Arrange the carbon fiber filaments in an "S" shape on the surface of the composite rubber, and then press another piece of composite rubber on top of it to obtain a sheet-like compound. Step (3) Take out the preheated vulcanizing mold and stainless steel pressure mesh. First, lay the sheet compound flat in the mold, then place the stainless steel pressure mesh on the surface of the sheet compound. After flattening, press the upper and lower molds together and put them back into the flat vulcanizing machine for vulcanization. After the set vulcanization time is reached in step (4), the mold in the vulcanizing machine is taken out, and the sheet vulcanized rubber is obtained after the mold is opened. The sheet vulcanized rubber is the composite thermally conductive rubber. Step (5) Adhere the composite thermally conductive rubber to the outer leading edge of the rotor shell.

2. The multi-level micro / nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor as described in claim 1, characterized in that, The outer leading edge of the rotor casing refers to the rotor root that is projected onto the first fifth of the chord length.

3. The multi-level micro / nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor as described in claim 1, characterized in that, Each bundle of the carbon fiber filaments (3) is 3K.

4. The multi-level micro / nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor as described in claim 1, characterized in that, The composite thermally conductive rubber comprises the following components in parts by weight: 100 parts of raw silicone rubber, 3 parts of sulfur, 2 parts of carbon fiber filaments, 0.1 parts of coupling agent, 2 parts of vulcanization accelerator, 9 parts of vulcanization activator, and a conductive modifier. The conductive modifier includes 1-5 parts of carbon nanotubes and 7.5-15 parts of copper powder, and the weight ratio of carbon nanotubes to copper powder is 1:

3.

5. The multi-level micro / nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor as described in claim 1, characterized in that, In step (3), the preheating temperature of the vulcanizing mold and the stainless steel pressure mesh is 175°C, and the preheating time is 5 min - 8 min.

6. The multi-level micro / nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor as described in claim 1, characterized in that, In step (1), the roller gap during the feeding process is 1mm, and the roller gap during the degassing and sheeting process is 1mm-1.5mm.

7. The multi-level micro / nano structure covering the leading edge of an anti-icing, de-icing, and wind-blown sand-resistant rotor as described in claim 1, characterized in that, In step (3), the vulcanization temperature is 175℃, the pressure is 70MPa, and the time is 10min-15min.

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