RU2578079C1 - Method of prevention of formation and removal of ice from composite structural elements and device for its implementation - Google Patents

Abstract

FIELD: heating.

SUBSTANCE: for prevention and removal of ice the surfaces exposed to icing are heated to a temperature of ice melting. The structural elements are covered with several layers, first with an electric-heat-insulating layer, then a layer of heating elements of electrically conductive polymeric materials, then a hydrophobic electrically insulating fluoroplastic film. Heating is controlled based on the sensor data. The device of prevention and removal of ice comprises a control unit, a current source, switching elements, sensors located on the structure elements.

EFFECT: removal of ice from the structural elements and prevention of barrier ice formation.

2 cl, 1 dwg

Description

The invention relates to the protection against icing of structural elements operating in air currents, in particular to anti-icing systems for aircraft, wind power plants, and can be used to prevent the formation and removal of ice on the outer surfaces of the wings of an aircraft, helicopter rotor blades, air blades propellers (propulsors) of wind power generators, etc.

Of the known methods of combating icing, such as mechanical, physico-chemical, thermal, the most effective and widespread is electrothermal [Ahmed Shinkafi, Craig Lawson. Enhanced Method of Conceptual Sizing of Aircraft Electro-Thermal Deicing System. World Academy of Science, Engineering and Technology International Journal of Mechanical, Aerospace, Industrial and Mechatronics Engineering Vol: 8 No: 6, 2014], which consists in ensuring the removal of ice or preventing its formation by heating the surface of the aircraft.

Known analogues of the method of preventing icing of structural elements of the aircraft are based:

- the use of anti-icing coatings applied to part of the outer surface of the aircraft [Pat. 2492115 Russian Federation, IPC B64D 15/12. Edge of the air intake of a nacelle of a turbojet engine. Roger K .; declared 03/12/2009; publ. 09/10/2013]. The essence of the invention lies in the fact that the means for eliminating icing comprise an anti-icing coating applied to at least a portion of the outer surface, the anti-icing binder matrix comprising at least one piezoelectric active element;

- the use of hydrophobic material deposited on a protected surface [US Pat. 2027640 Russian Federation, IPC 6 B64D 15/00. Device for protecting the design of the aircraft from icing. Egorshev A.V., Komarov V.A .; declared 11/27/1991; publ. January 27, 1995]. The essence of the invention lies in the fact that the device is equipped with separate profiled sections placed without a gap on the surface to be protected, each of which contains a metal plate made of a material identical to the material of the surface to be protected, fastened by a layer of conductive sealant with a layer of hydrophobic material, the inner surface of which is metallized, this in the hydrophobic layer is embedded N flat electromagnetic coils, interconnected within each section, and the coils azhdoy section connected to the power source through the channel selector;

- on a method of preventing icing of the wings of aircraft [Pat. 2504502 Russian Federation, IPC 8 B64D 15/00. A way to combat icing of the wings of aircraft / Potapov Yu.F., Miller A.B .; declared 11/28/12; publ. 01/20/2014], selected as a prototype of the method of preventing the formation and removal of ice from composite structural elements. The essence of the method is that surfaces subject to icing are heated to the melting temperature of the ice and the water formed after the melting of the ice is collected in containers installed in the wing cavity to prevent its freezing in the form of barrier ice;

- the use of electrothermal de-icing system [Pat. 2226481 Russian Federation, IPC 7 B64D 15/00, B64D 15/12, Н05В 3/84. Electrothermal de-icing system, for example, for helicopter blades / G. Blutshtein, E. Busygin, S. Golberg, V. Nam, V. V. Shershukov; declared 07/19/2002; publ. 04/10/2004], selected as a prototype device for preventing the formation and removal of ice from composite structural elements. A prototype device for preventing the formation and removal of ice from composite structural elements contains thermoelectric heaters connected to a three-phase AC source through switching elements, current transformers, the windings of which cover the supply wires of thermoelectric heaters, a control unit whose outputs are connected to the control inputs of the switching elements, and the inputs - with the windings of current transformers, operational amplifiers are also introduced into the system through which the windings of the transformer sformatorov current inputs are connected to the control unit, the heaters are formed in pairs, each pair of which is connected to a bridge in the end portion of the blade, covering the inner pair of heaters.

Given as prototypes, the method and device for preventing the formation and removal of ice from composite structural elements have several disadvantages. The main disadvantages are:

- high specific energy consumption due to the large heating area of the protected surfaces;

- high probability of overheating and burnout of structural elements made of composite materials;

- a high probability of formation of barrier ice on the surface of structural elements in areas adjacent to the edges of the heating zone;

- high probability of internal stresses in structural elements due to the difference in the coefficients of thermal expansion of materials of heating elements and elements of protected surfaces.

The technical problem of the invention to be solved is to create an integrated de-icing system that works in both passive and active modes and provides a reduction in specific energy consumption by reducing the average temperature of the heating elements while protecting structural elements from icing, reducing the likelihood of formation of barrier ice, reducing the likelihood of overheating and burnout of structural elements made of composite materials, reducing the likelihood of internal apryazheny in structural members through the use of materials with similar coefficients of thermal expansion value.

The technical problem to be solved is a method for preventing the formation and removal of ice from composite structural elements, in which surfaces subject to icing are heated to the melting temperature of ice, is achieved by the fact that heating elements for heating surfaces subject to icing are made of electrically conductive polymeric materials and placed in zones icing directly on the outer surface of structural elements separated from them by an electrothermal insulating layer; x elements containing heating elements, and at the same time adjacent to the heating elements zones are covered with a hydrophobic electrically insulating fluoroplastic film, preventing the formation of barrier ice, while the heating is controlled by the control unit based on data obtained using sensors located on the structural elements in the zones icing and on the basis of data relating to the icing conditions of the structural element.

The proposed method for preventing the formation and removal of ice from composite structural elements is implemented by a device for preventing the formation and removal of ice from composite structural elements. The technical problem to be solved is a device for preventing the formation and removal of ice from composite structural elements, consisting of heating elements connected to a current source through switching elements, a control unit whose outputs are connected to the control inputs of the switching elements, and the inputs with sensors are achieved by the fact that electrothermal insulation layer designed to be located on the outer surface of structural elements in icing zones, over which heaters are placed On the other hand, they are coated with hydrophobic electrically insulating fluoroplastic film, which at the same time covers the areas of structural elements adjacent to the heating elements, on which barrier ice can form.

The device for preventing the formation and removal of ice from composite structural elements, shown in the drawing, contains a hydrophobic electrically insulating fluoroplastic film 1, which prevents the formation of barrier ice and acts as a passive anti-icing coating, which, by means of a heat-conducting adhesive joint 2, is attached to the heating elements 3, which are electrically insulated adhesive joint 4 are attached to the outer surface of structural elements 5 in iced areas tions, for example the front edge of the wing of the aircraft, the heating elements 3 are connected via the switching elements 6, 7 to a current source, the control unit 8, the outputs of which are connected to the control inputs of the switching elements 6 and 9, the inputs to the sensors.

The icing zone is the surface area where ice is formed.

Icing conditions - a set of atmospheric conditions (water content, temperature, droplet diameter, atmospheric pressure, as well as flight speed) under which icing is observed.

Barrier ice - icing in the form of rollers or separate streaks behind the surface heating zone.

Consider the implementation of the method of preventing the formation and removal of ice from composite structural elements on the example of an aircraft and the operation of the device to prevent the formation and removal of ice from composite structural elements of the aircraft, shown in the drawing.

When the speed of the aircraft is less than 0.3 M (Mach M speed), the external structural elements of the aircraft are protected from icing by a hydrophobic electrically insulating fluoroplastic film 1 [Panshin Yu.A. and other fluoroplastics. L .: Chemistry, 1978]. The supercooled droplets contained in the atmosphere and falling on the fluoroplastic film, due to low adhesion, are discharged from the structural elements of the aircraft under the influence of the oncoming flow. In the conditions of ice formation or ice formation on the surface of structural elements of the aircraft, sensor 9 [ПУ 3.390.252 ТО Icing type ice detector СО - 1. Technical description] gives a signal to control unit 8 [Kasatkin AS, Nemtsov MV Electrical Engineering M .: Energoatomizdat, 1995], which launches an anti-icing system in a cyclogram with a time delay between cycles, depending on the icing conditions. From the output of the control unit 8, signals are sent to the switching elements 6 [Voloshin S. Modern semiconductor load switches. Components and technologies, No. 7, 2003], which connect the groups of heating elements 3 [Petrov Yu.B. The basics of electric heating: text of lectures / L .: SPbGETU, 1990. - 47 p.]. Depending on the outdoor temperature, the duration and period of connection of the heating elements 3 varies. The lower the temperature of the outside air, the longer the duration and the shorter the connection time for the heating elements 3. 1 drops and ice residues formed on the surface of the hydrophobic electrically insulating fluoroplastic film are thrown as a result of ice thawing from the structural elements of the aircraft under the influence of the oncoming flow. Due to the fact that the zone of structural elements on which the formation of barrier ice is possible is covered by a hydrophobic electrically insulating fluoroplastic film 1, the intensity of formation of barrier ice is reduced.

Thus, the hydrophobic electrically insulating fluoroplastic outer coating prevents the formation of barrier ice on structural elements, which allows to reduce the heating area occupied by heating elements, thereby reducing energy consumption for the anti-icing system, and together with heating elements made of polymeric materials, to reduce the likelihood of overheating and burnout of structural elements made of composite materials, reduce the likelihood of internal stresses in the con structural elements through the use of materials with close coefficients of thermal expansion.

Claims (2)

1. A method of preventing the formation and removal of ice from composite structural elements, in which surfaces subject to icing are heated to the melting temperature of the ice, characterized in that the heating elements for heating surfaces subject to icing are made of electrically conductive polymeric materials and are placed directly in the icing zones on the outer surface of structural elements separated from them by an electrothermal insulating layer, on top is a portion of structural elements containing heat The active elements and, simultaneously, the zones adjacent to the heating elements are covered with a hydrophobic electrically insulating fluoroplastic film, preventing the formation of barrier ice, while the heating is controlled by the control unit on the basis of data obtained using sensors located on the structural elements in the icing zones and based on data related to icing conditions of a structural member. 2. Device for preventing the formation and removal of ice from composite structural elements, consisting of heating elements connected to a current source through switching elements, a control unit, the outputs of which are connected to the control inputs of the switching elements, and the inputs with sensors, characterized in that it contains an electrically insulating layer , designed to be located on the outer surface of structural elements in icing zones, on top of which heating elements are placed, on top of which s available hydrophobic PTFE electrically insulating film, covering both adjacent to the heating elements zone of structural elements, which can form a barrier of ice.

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