A new anti-icing system based on active and passive coupling

Abstract

The present invention relates to a kind of brand-new anti-icing system / device based on active-passive coupling, belong to anti-icing field.The device mainly includes the anti-icing combination layer 2 bonded to the upper surface of airfoil 1, the anti-icing combination layer 2 is made up of super-hydrophobic coating 3, thermal insulation layer 4, heating element 5, thermal insulation layer 6, thermal wire 7, the thermal insulation layer 6 is bottom layer, it is bonded to the upper surface of airfoil 1, thermal insulation layer 6 upper surface is bonded to heating element 5, heating element 5 upper surface is bonded to thermal insulation film 4, thermal insulation film 4 surface perforations expose thermal wire 7 to thermal insulation film 4 surface outside, thermal insulation film 4 upper surface spraying super-hydrophobic coating 3.The thermal wire 7 is staggered along span and chord, runs through super-hydrophobic coating 3 and thermal insulation layer 4, its bottom is connected with heating element 5, for conducting the heat produced by heating element 5, and tip is exposed in air. The power supply 9 realizes periodic heating of the anti-icing process through the wires; the present invention involves a new active-passive coupled anti-icing method for aircraft, which is formed by coupling the active anti-icing method of electrothermal anti-icing and the passive anti-icing method of super-hydrophobic anti-icing.

Description

Technical Field

[0001] Field

[0002] The present invention relates to a new anti-icing system based on active and passive coupling, belonging to the field of anti-icing. Background Art

[0003] Accidents caused by icing affect a wide range of sectors, including aerospace, power systems, and ground transportation, causing significant inconvenience to people's lives and work. In recent years, flight accidents have occurred frequently, many of which were caused by aircraft icing. Icing has become a major threat to aviation safety. According to statistics, in just eight years between 2009 and 2017, icing-related accidents accounted for 28% of all global accidents, resulting in significant losses. Icing on aerodynamic components creates irregular aerodynamic shapes that significantly impact lift-drag characteristics. Statistics show that icing can reduce lift by 30% and increase drag by 140%. Engine icing not only reduces engine efficiency but can also cause engine surge and, in more serious cases, engine shutdown. Icing on other components, such as sensors, windshields, and radomes, can impair aircraft information collection and transmission, leading pilots to misjudge the aircraft's flight status and make incorrect maneuvers, seriously threatening flight safety. For civilian aircraft, icing can reduce economic efficiency. Icing on wind turbine blades not only causes errors in wind speed and direction measurements, but also affects aerodynamic characteristics and power generation output. Falling ice fragments from the blades can also pose a threat to personal safety. Therefore, in-depth research on the icing problem is needed to develop better anti-icing and de-icing methods.

[0004] Because icing poses a serious threat to flight safety, the aviation industry has been researching aircraft icing since the 1940s, proposing and applying various anti-icing methods, including thermal de-icing, liquid anti-icing, and mechanical de-icing. Hot gas de-icing typically uses air from the engine's compressor to transfer heat to the surfaces of de-icing components. However, this method significantly reduces engine efficiency and has high thermal inertia, significantly limiting its application prospects. Electric de-icing uses heating elements to generate heat and transfer it to the de-icing area. While this method improves engine efficiency, it also increases power consumption and has no substantial impact on energy conservation. Liquid de-icing involves spraying anti-icing fluids such as isopropyl alcohol and ethylene glycol onto the surfaces of ice-prone components. This method is primarily used for ground de-icing. However, carrying anti-icing fluid during flight reduces payload, damages aircraft surfaces such as the skin, and poses a certain environmental risk. Mechanical deicing uses mechanical methods to break up the ice layer between the ice layer and the icing surface, reducing the ice's adhesion, and then removes it under the action of aerodynamic forces, centrifugal forces, or vibration. For example, expansion tube deicing can damage the aerodynamic shape due to the bulge in the expansion tube, affecting lift-drag characteristics. Although electric pulse deicing reduces energy consumption, its high-frequency vibration and the skin riveting process significantly reduce the service life of the skin. In addition, some new deicing methods such as super-hydrophobic deicing and plasma deicing have also been further developed. Super-hydrophobic deicing uses the wetting properties of super-hydrophobic materials to achieve the purpose of delaying ice formation, but it cannot fundamentally prevent ice in harsh flight conditions. Plasma deicing uses the thermal effect of ionized air to achieve deicing, but this method requires a high-voltage power supply to implement, making it less applicable to large civilian airliners. These new deicing methods are limited in their deicing effectiveness and usage conditions and are still only in the research stage. Therefore, there is an urgent need to propose a new deicing method for research and application. Summary of the Invention

[0005] Most of the aforementioned anti-icing methods have been used for aircraft de-icing with significant effectiveness. Some newer de-icing methods, currently under research, have also achieved these goals. However, the de-icing process consumes excessive energy, resulting in poor economic efficiency and severe damage to the aerodynamic properties of aircraft aerodynamic components. This is the technical problem addressed by the present invention.

[0006] The present invention addresses the lack of cost-effectiveness and practicality of current aircraft de-icing methods by proposing a novel aircraft de-icing method and device that couples active and passive de-icing. This novel method offers advantages such as reduced energy consumption and improved cost-effectiveness during the aircraft de-icing process.

[0007] The technical solution of the present invention is: a new active-passive coupled anti-icing system for aircraft, mainly comprising an anti-icing composite layer 2 bonded to the upper surface of an airfoil 1,

[0008] The anti-icing combination layer 2 is composed of a super-hydrophobic coating 3, a thermal insulation layer 4, a heating element 5, a thermal insulation layer 6, and a thermal wire 7. The thermal insulation layer 6 is the bottom layer, which is bonded to the upper surface of the airfoil 1. The upper surface of the thermal insulation layer 6 is bonded to the heating element 5. The upper surface of the heating element 5 is bonded to the thermal insulation film 4. The surface of the thermal insulation film 4 has holes opened to expose the thermal wire 7 to the outside of the surface of the thermal insulation film 4. The super-hydrophobic coating 3 is sprayed on the upper surface of the thermal insulation film 4.

[0009] The heat-conducting wires 7 are staggered in the span direction and the chord direction, passing through the super-hydrophobic coating 3 and the thermal insulation layer 4, and their lower parts are connected to the heating element 5 for conducting the heat generated by the heating element 5, with their tips exposed to the air;

[0010] The power supply 9 realizes periodic heating during the deicing process through the wires.

[0011] The beneficial effects of the present invention are as follows: The present invention relates to a new active-passive coupled anti-icing method for aircraft, which is formed by coupling the active anti-icing method of electrothermal anti-icing and the passive anti-icing method of superhydrophobic anti-icing. This method differs from the existing superhydrophobic electrothermal composite anti-icing method in the anti-icing mechanism. As can be seen from the above, electrothermal anti-icing consumes a lot of energy, and superhydrophobic anti-icing cannot fundamentally achieve the anti-icing effect under flight conditions. Combining the two can reduce energy consumption and achieve the anti-icing effect. However, in this method, all supercooled water droplets collide with the superhydrophobic surface during the anti-icing process, and the entire surface needs to be heated to achieve the anti-icing effect. The present invention optimizes the electrothermal anti-icing in the superhydrophobic electrothermal composite anti-icing method to further reduce the anti-icing energy consumption, that is, optimizing the surface anti-icing of the electric heating film to the point anti-icing of the thermal wire. The anti-icing mechanism is also different from the existing super-hydrophobic electrothermal composite anti-icing method. When super-cooled water droplets hit the anti-icing surface of the aircraft, the super-cooled water droplets hit the super-hydrophobic coating. Due to the hydrophobic effect of the super-hydrophobic coating, the water droplets bounce, roll, and other behaviors. When the water droplets contact the thermal wire, the rolling behavior stops due to the blocking effect of the thermal wire. The water droplets gather at the tip of the thermal wire and nucleate and freeze at the tip to form small ice particles. At this time, most of the heat is transferred to the tip of the heating wire through power heating. These small ice particles melt at the tip. Under the action of aerodynamic force, the melted small ice particles are carried away by the airflow, thereby achieving the anti-icing effect. The above anti-icing phenomenon is not available in the existing super-hydrophobic electrothermal composite anti-icing method. In addition, since the thermal insulation effect of the thermal insulation layer adopts periodic heating as the heating method, energy consumption is minimized;

[0012] The aircraft anti-icing method involved in the present invention proposes a new anti-icing method, which adopts the form of point heating and surface insulation and is combined with superhydrophobic anti-icing. That is, the input heat is used to melt ice at the tip of the heating wire, and the insulation layer is periodically heated, which makes this method have greater advantages in economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A three-dimensional schematic diagram of the solution in the embodiment;

[0014] Figure 2 3D schematic diagram of the flexible film combination layer in the embodiment;

[0015] Figure 3 A two-dimensional schematic diagram of the arrangement and wiring of each layer in the embodiment;

[0016] Figure 4 Schematic diagram of the anti-icing process in the embodiment;

[0017] Figure 5 It is a partial schematic diagram of the anti-icing principle in the embodiment. DETAILED DESCRIPTION

[0018] In this embodiment, a new active-passive coupled anti-icing system / device for an aircraft is provided, which comprises a NACA0012 airfoil 1, an anti-icing composite layer 2, a super-hydrophobic coating 3, a thermal insulation film 4, a heating element 5, a thermal insulation layer 6, a thermal conductive wire 7, a wire 8, and a power supply 9.

[0019] The upper surface of the NACA0012 airfoil 1 is bonded to the lower surface of the anti-icing combination layer 2. The anti-icing combination layer 2 is composed of a super-hydrophobic coating 3, a thermal insulation layer 4, a heating element 5, a thermal insulation layer 6, and a thermal wire 7. The upper surface of the NACA0012 airfoil 1 is bonded to the thermal insulation layer 6, the upper surface of the thermal insulation layer 6 is bonded to the heating element 5, the upper surface of the heating element 5 is bonded to the thermal insulation film 4, and holes are opened on the surface of the thermal insulation film 4 to expose the thermal wire 7 to the outside of the surface of the thermal insulation film 4. The super-hydrophobic coating 3 is sprayed on the upper surface of the thermal insulation film 4, and supercooled water droplets drip on the upper part of the upper surface of the anti-icing combination layer.

[0020] The novel active-passive coupled anti-icing system / device for aircraft consists of two anti-icing systems: an active anti-icing method (electric heating anti-icing) and a passive anti-icing method (super-hydrophobic anti-icing).

[0021] The NACA0012 airfoil 1 has a chord length of 400 mm and a span length of 300 mm, and is made of aluminum alloy;

[0022] The anti-icing composite layer 2 has a chord length of 300 mm and a span length of 300 mm. It is a flexible membrane composite layer composed of a super-hydrophobic coating 3, a thermal insulation layer 4, a heating element 5, a thermal insulation layer 6, and a thermal conductive wire 7.

[0023] The super-hydrophobic coating 3 has a chordal length of 300 mm, a span length of 300 mm, a thickness of 10-25 μm, and is sprayed with a super-hydrophobic material. The contact angle θ of the super-cooled water droplet 10 on the surface of the super-hydrophobic coating 3 is greater than 150°.

[0024] The insulation layer 4 has a chord length of 300 mm and a span length of 300 mm. The lower surface of the insulation layer 4 is bonded to the upper surface of the heating element 5. This layer has a good insulation effect. In a low temperature environment, the heat generated by the heating element 5 is blocked by the insulation layer 4, and the heat dissipation is slow.

[0025] The heating element 5 has a chord length of 300 mm, a span length of 300 mm, and a thickness of 18 μm. It is located between the thermal insulation layer 4 and the heat insulating layer 6 and is connected to the heat conducting wire 7. The heating element 5 is powered by a regulated DC power supply to generate heat, which is then conducted to the tip of the heating element 5 via the heat conducting wire 7.

[0026] The thermal insulation layer 6 is 300 mm long in the chord direction and 300 mm long in the span direction. Its lower surface is bonded to the anti-icing surface, and its upper surface is bonded to the lower surface of the heating element 5. The thermal insulation layer 6 is made of high-density thermal insulation cotton with a low thermal conductivity of less than 0.034 W / m﹒k, so that most of the heat generated by the heating element 5 is transferred to the thermal wire 7, thereby improving energy efficiency and reducing energy consumption.

[0027] The heat conducting wires 7 have a diameter of 0.1 mm and are staggered in the spanwise and chordwise directions, with a spacing of 10 mm between the two heating wires. They penetrate the super-hydrophobic coating 3 and the thermal insulation layer 4, and are connected to the heating element 5 at the bottom to conduct the heat generated by the heating element 5. The tips are exposed to the air for 5 mm.

[0028] The conductor 8 is a copper conductor with good electrical conductivity;

[0029] The power supply 9 is a programmable DC regulated power supply with an output voltage of 0-50V and an output current of 0-20A, which meets the power required for anti-icing and can realize periodic heating during the anti-icing process;

[0030] The supercooled water droplets are deionized water droplets in a supercooled state. Generally, under real icing meteorological conditions, water droplets in clouds are in a supercooled state.

[0031] A kind of brand-new based on active-passive coupling aircraft anti-icing method of the present invention, when aircraft flies in icing condition, the supercooled water droplets in the air impact on anti-icing surface, what first contacts with supercooled water droplets is super-hydrophobic coating, because super-hydrophobic coating is excellent in surface wetting characteristics, supercooled water droplets bounce on its surface, rolling and other behaviors.When supercooled water droplets and thermal wire collide, stop rolling and gather at heating wire tip, and freeze into tiny ice particles, freeze in the form of points on the surface.Power is turned on, heating element generates heat, and a part is rapidly transferred to tip by thermal wire to melt tiny ice particles, and another part then maintains the temperature of thermal insulation layer.In addition, the heat of heating element is transferred to thermal insulation layer, due to its heat preservation effect, plus periodic heating mode, surface temperature always maintains above freezing point, namely the super-hydrophobic coating surface temperature that contacts with thermal insulation layer upper surface also always maintains above freezing point, supercooled water droplets will not freeze immediately when impacting super-hydrophobic surface, but bounce to gather at thermal wire tip and just freeze. When there is no ice in the aircraft skin anti-icing area, turn off the DC regulated power supply.

Claims

1. An aircraft active-passive coupled anti-icing system, characterized in that: The invention comprises an anti-icing composite layer (2) bonded to the upper surface of an airfoil (1), wherein the anti-icing composite layer (2) is composed of a super-hydrophobic coating (3), a thermal insulation layer (4), a heating element (5), a thermal insulation layer (6), and a thermal conductive wire (7); the thermal insulation layer (6) is the bottom layer and is bonded to the upper surface of the airfoil (1); the upper surface of the thermal insulation layer (6) is bonded to the heating element (5); the upper surface of the heating element (5) is bonded to the thermal insulation layer (4); holes are opened on the surface of the thermal insulation layer (4) to expose the thermal conductive wire (7) to the outside of the surface of the thermal insulation layer (4); and the upper surface of the thermal insulation layer (4) is sprayed with a super-hydrophobic coating (3); the thermal conductive wire (7) is staggered in the span direction and the chord direction; the thermal conductive wire (7) is composed of two heating wires, which pass through the super-hydrophobic coating (3) and the thermal insulation layer (4); the lower part of the thermal conductive wire (7) is connected to the heating element (5) for conducting heat generated by the heating element (5); and the tip is exposed to the air; The power supply (9) realizes periodic heating of the anti-icing process through the wire; When the aircraft flies under icing conditions, supercooled water droplets in the air hit the surface of the superhydrophobic coating (3) and bounce and roll on the surface. When the supercooled water droplets collide with the heat-conducting wire (7), they stop rolling and gather at the tip of the heating wire and freeze into small ice particles, freezing in the form of points. After ice forms, the power supply (9) is turned on to allow the heating element (5) to generate heat. A portion of the heat is quickly transferred from the heat-conducting wire (7) to the tip of the heating wire to melt the tiny ice particles, and the other portion of the heat is used to maintain the temperature of the thermal insulation layer (4). Due to the thermal insulation effect of the thermal insulation layer (4) and the periodic heating, the surface temperature of the thermal insulation layer (4) is always maintained above the freezing point, and the surface temperature of the super-hydrophobic coating (3) in contact with the upper surface of the thermal insulation layer (4) is also always maintained above the freezing point. After there is no ice, turn off the power (9).

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