RU2233232C2 - Method of anti-icing protection of structural members of flying vehicles - Google Patents

Abstract

FIELD: aeronautical engineering; anti-icing systems for flying vehicles by use of velocity head of surrounding air.

SUBSTANCE: proposed method consists in heating the structural members to ice thawing temperature. Thermal energy required for heating the structural members is obtained by conversion of kinematic energy of velocity head of incoming air and is transmitted to area subject to icing due to accumulation of heat. Acoustic resonators manufacture from highly heat conducting material may be mounted on structural members of flying vehicle.

EFFECT: increased flying range; avoidance of additional load on power system of flying vehicle; reduced mass of flying vehicle.

4 cl, 2 dwg

Description

The invention relates to aircraft, in particular to anti-icing systems of an aircraft (LA), and can be used to prevent the formation of ice on the outer surfaces of the wings of the aircraft, the input devices of gas turbine engines of the aircraft, helicopter rotor blades, propeller blades (propellers), wind power generators etc. That is, in any areas of power engineering, where you can use the high-pressure head of the surrounding air.

A known method of mechanical destruction of ice on the structures of the aircraft [RF Patent No. 93053570, class. B 64 D 15/16, publ. 06/27/1996], which consists in the creation of a protected skin and a layer of ice located on it, repeated impulse strains separated by pauses. An elastic material with ferromagnetic plates pressed inside the latter is fixed on the outer surface of the protected sheathing in areas subject to icing, and the elastic material is formed by the electric pulse method of oscillation of the elastic material when ice forms on it, by exposing the ferromagnetic plates to an electromagnetic field of alternating sign concentrated in the region of the latter.

The disadvantages of this invention include:

- high energy intensity of the method, due to the fact that on-board sources of electricity are used to form an electromagnetic pulse;

- increasing the weight of the aircraft due to the need to install additional equipment to create pulsed deformations in the skin;

- reducing the flight range of the aircraft and reducing the distance to the "return point" in emergency situations due to additional fuel consumption for the formation of vibrations of the elastic skin material;

- reduction of the operational life of the main aircraft engines, which is associated with additional energy costs for ice removal;

- the complexity of the design due to the large number of structural elements used in the method, namely, elastic sheathing elements, ferromagnetic inserts, switchgear and wires for supplying electricity, etc .;

- reducing the lining life due to damage from deformation when creating electromagnetic pulses;

- the complexity of the method, due to the fact that the analogue is the destruction of the already formed layer of ice, and not the prevention of its formation. Therefore, it is necessary to carry out additional operations to enhance the operation of devices that generate oscillations.

The invention is known “Resistance Elements for heating an aerodynamic surface and devices including such elements” [US Patent No. 5971323, class. B 64 D 15/00, B 64 L 01/02, publ. November 26, 1999], which consists in the fact that to remove icing, the aerodynamic surface is heated using several resistance elements, each of which consists of electrically conductive glass fibers and is located in the aerodynamic surface in close proximity to its leading front parallel to it. An electric current is supplied to the resistance elements, which causes their heating, associated with the Joule effect.

The disadvantages of this known invention are:

- reducing the flight range of the aircraft due to the need for fuel consumption for heating aerodynamic surfaces;

- the complexity of the design due to the need for a large number of resistance elements and their constituent electrically conductive glass fibers;

- increasing the weight of the aircraft as a whole by increasing the mass of fuel on board to generate electricity needed for heating;

- additional load on the aircraft power plant due to the selection of electricity from the main engines for heating surfaces exposed to the risk of icing.

A known method and apparatus for using heated fuels to remove icing from an airplane [US Patent No. 5558303, class. B 64 D 15/02, publ. September 24, 1996]. The method consists in the fact that to remove icing from the aerodynamic surface it is heated to ice melting temperatures, using heat from the fuel preheated to temperatures high enough to transfer thermal energy through the fuel tanks located in the wings to the outer region of the wings .

The disadvantages of this invention are:

- limited use in aircraft of various brands, associated with the need for a mandatory location of the fuel tank in the aircraft wing;

- high operating costs due to the need for the availability of special equipment at the aerodromes for pre-heating the fuel.

The invention is known “Slat of an airplane with air heating” [RF Patent No. 2083441, cl. B 64 D 15/04, publ. July 10, 1997], which consists in the fact that for heating structural elements subject to icing, an air heating pipe is used, which is installed in the slat of the aerodynamic surface on a support element made in the form of a block. The block is mounted on the diaphragm and spring loaded relative to it with a flat corrugated spring. The air heating pipe is located in the slat toe and is attached with a clamp to the longitudinal diaphragm, and the clamp is fixed on the side of the slat toe with the possibility of a fixed strain relief.

The disadvantages of this invention are:

- weight gain;

- increase the load on the aircraft's onboard energy system;

- the complexity of the design, the high cost of manufacturing and installation of the anti-icing device on board the aircraft;

- large overall dimensions of the structural elements that make up the anti-icing device, in particular air heating pipes.

Of the known methods closest to the invention in terms of technical nature, the achieved result and selected as a prototype is the anti-icing method and the microwave anti-icing system of the aircraft [US Patent No. 5615849, class. B 64 D 15/00, publ. 04/01/1997], in which the structural elements of the aircraft in areas of risk of icing, the surface is heated to ice melting temperatures t> 0 ° C. Microwave energy received from a microwave generator is absorbed by a special heat-absorbing tube located in the slat of the aerodynamic surface. Then the received microwave energy is converted into heat through the same absorption tube. For the most efficient conversion of microwave energy into heat, a special coating with high absorption properties is applied to the inner surface of the tube, and an insulator mirror is installed. Then, thermal transfer rudders transfer thermal energy to the structural elements of the aircraft, for example, to the skin of the leading edge of the wing, or to another aerodynamic surface, the rotor of the aircraft, etc. The temperature of these elements is kept constant so that it is significantly higher than the freezing temperature. Thus, the structural elements of the aircraft are heated, thereby preventing icing.

The disadvantages of this invention are:

- reducing the flight range of the aircraft and reducing the distance to the "return point" due to the need for additional fuel consumption for heating exposed to icing surfaces;

- a large load on the onboard power system, due to the fact that the microwave energy stream is obtained through a microwave generator that uses electricity from the onboard network of the aircraft to create this stream;

- increasing the weight of the aircraft due to the fact that the composition of the icing prevention system includes a large number of structural elements, namely a microwave generator, radial transfer rudders, a heat absorbing tube. Therefore, in conjunction with the installation elements, the de-icing system is a very complex structure and occupies a significant part of the internal space of the aerodynamic surface of the aircraft.

The disadvantages of the application of this invention also include the high cost of manufacturing structural elements of the anti-icing system due to the fact that expensive equipment and materials are used to manufacture the microwave generator and the absorption tube.

Thus, three main methods are currently used to remove or prevent the formation of ice on the outer surfaces of aircraft, namely:

- by supplying heated gases or liquids through a pipeline;

- by electric heating;

- by mechanical means, for example, vibration nets or blocks attached to or integrated into the surface of the aircraft.

Obviously, the use of all these known methods leads to the complexity of the design of the aircraft as a whole, requires additional energy consumption for heating, and therefore, to reduce the flight range and increase the weight of the aircraft.

It should also be noted that all the methods and devices discussed above for their implementation are not involved during the entire flight of the aircraft, that is, they are aimed at destroying the already formed layer of ice, and not at preventing its formation. In the case, if you implement these methods or use such devices continuously, the cost of electricity, and therefore the fuel consumption for obtaining this energy, will be unacceptable from the point of view of the operating conditions of the aircraft.

The basis of the invention is the task of increasing the flight range of the aircraft, reducing the load on the on-board energy system and, as a result, eliminating the additional fuel consumption for heating surfaces at risk of icing, as well as reducing the weight of the aircraft.

The problem is solved in that the way to prevent icing of structural elements of aircraft is that structural elements of the aircraft in areas of the surface at risk of icing are heated to ice melting temperatures t> 0C °. According to the invention, the thermal energy necessary for heating is obtained by converting the kinetic energy of the high-speed pressure of air coming in at a speed of M≥0.4. Then, the received thermal energy is transferred to surface areas subject to icing hazard due to heat accumulation.

To convert the kinetic energy of the velocity head of the incident air into heat in the frontal parts of the structural elements of the aircraft, for example in the frontal part of the wing, acoustic resonators are installed. Then, high-frequency shock waves are generated in them, after which the blind ends of the resonators are heated to accumulate heat.

In some cases, for the most efficient use of the energy of the high-speed pressure of the oncoming air, acoustic resonators are installed along the front of the frontal parts of the structural elements of the aircraft.

To ensure the accumulation of heat for heating the surfaces of structural elements of the aircraft, acoustic resonators are made of highly heat-conducting material, after which they are separated from each other by separation elements.

In the claimed invention provides an increase in the flight range of the aircraft and an increase in the distance to the "return point" due to the elimination of the need for additional fuel consumption for heating exposed to icing surfaces. This is achieved due to the fact that the heating of the surfaces of the structural elements of the aircraft occurs due to the accumulation of heat. That is, high-frequency shock waves are generated in acoustic resonators and the blind ends are heated, and the received thermal energy gradually propagates from the blind end of the resonator throughout the entire structural element. That is, after the device enters the mode, the temperature along the entire length of the resonator will be constant. In particular, in the casing of an aircraft structural element, it will increase from ambient temperature to ice melting temperature. Thus, the invention achieves the prevention of ice formation in areas of the surface of aircraft structural components that are at risk of icing.

The invention eliminates the additional load on the onboard power system due to the fact that to combat icing of the edges of the structural elements of the aircraft using acoustic resonators. The operation of the acoustic resonator, in this case, is based on the conversion of environmental energy, therefore, it does not require electricity from an onboard source.

In the claimed invention, a reduction in the weight of the aircraft is achieved due to the fact that acoustic resonators are installed in the frontal parts of the structural elements of the aircraft. The entire icing prevention system consists of a small number of parts, namely, a set of acoustic resonators, which themselves have a fairly simple design. It is known that an acoustic resonator is a body with a blind end and has small dimensions and weight.

A positive feature of the application of the invention is to reduce the cost of manufacturing structural elements of the de-icing device, since the acoustic resonator has a fairly simple design and does not require special expensive equipment for its manufacture. All structural elements are made of accessible materials, the cost of which is significantly lower than the cost of the materials of the elements of the system of the closest analogue.

In FIG. 1 shows a graph of the temperature of the blind end of the resonator with a change in the Mach number M; in FIG. 2 is a diagram of the propagation of thermal energy from the blind end of the resonator to the skin of a structural element in an area prone to icing.

The proposed method for preventing icing of structural elements of the aircraft is that:

- get the thermal energy necessary for heating by converting the kinetic energy of the high-pressure head, which rushes in at a speed M≥0.4 of air (see Fig. 1);

- transfer the received thermal energy to the surface areas at risk of icing due to heat accumulation;

- heat the structural elements of the aircraft in areas of the surface exposed to icing risk to ice melting temperatures t> 0C °.

The conversion of the kinetic energy of the velocity head of the incoming air into heat is carried out as follows:

- install acoustic resonators in the frontal parts of the structural elements of the aircraft, for example in the frontal part of the wing;

- generate high-frequency shock waves in acoustic resonators;

- heat the blind ends of the resonators to accumulate heat.

The heating of the surfaces of the structural elements of the aircraft occurs due to the accumulation of heat. Thermal energy gradually propagates from the blind end of the resonator throughout the structural element (see Fig. 1).

When the environmental flow runs onto the frontal part of the aircraft structural element with a speed M≥0.4, the ratio Θ _{r of the} temperature of the blind end of the resonator to the temperature at the inlet of the resonator gradually increases.

where Θ _r is the ratio of the temperature of the blind end of the resonator to the temperature at the entrance to the resonator;

T _gk is the temperature of the blind end of the resonator;

T _I - the temperature at the entrance to the resonator.

At M = 0, that is, in the absence of a run-in of the environmental flow: Θ _r = 1.

During the flight, the ambient air flow runs at a certain speed onto the frontal parts (leading edges) of the aircraft structural elements with acoustic resonators installed in them. In this case, high-frequency shock waves are generated in the resonators, which leads to the irreversible conversion of kinetic energy into thermal energy, that is, to heating the blind end of the resonator.

The experiments showed that at 0 <M <0.4 the use of an acoustic resonator is inefficient, since an increase in the temperature of the blind cavity wall is not enough to heat the surface exposed to the risk of icing. That is, T _{gk is} slightly different from the ambient temperature.

When the speed of the incoming air flow M = 0.4, an increase in the ratio Θ _r will be sufficient to prevent icing of the structural elements of the aircraft (see Fig. 1).

At the initial time τ _{о, the} temperature at the inlet to the resonator T _in is equal to the ambient temperature T _n (see Fig. 2). Gradually, due to the accumulation of heat during the time the device reaches the regime (τ ₁ , τ ₂ , ...), thermal energy from the blind end of the resonator propagates along its entire length, as well as throughout the frontal part of the skin of the aircraft structural element.

After the device enters the mode during the entire flight time of the aircraft τ∞, the temperature along the entire length of the resonator will be constant. Including, in the casing of the structural element, the temperature will increase from the ambient temperature T _n to the ice melting temperature T _total.∞ :

T _{total .∞} > T _{total. 2} > T _{total. 1} > T _n .

Thus, the invention achieves the prevention of ice formation in areas at risk of icing of aircraft structural elements.

In some cases, for the most efficient use of the energy of the high-speed pressure of the oncoming air, acoustic resonators are installed along the front of the frontal parts of the structural elements of the aircraft.

To ensure the accumulation of heat for heating the surfaces of aircraft structural elements, acoustic resonators are made of highly conductive material, after which they are separated from each other by separation elements.

The use of the proposed method of preventing icing will provide an increase in the flight range of the aircraft due to the elimination of the need for additional fuel consumption for heating the icy surfaces of the aircraft at risk of icing.

The invention will eliminate the additional load on the onboard power system of the aircraft due to the use of an acoustic resonator, the operation of which does not require energy from an onboard source. In the claimed invention, a reduction in aircraft weight is achieved due to the fact that the entire icing prevention system consists of a small number of parts, namely, a combination of acoustic resonators, which themselves have a fairly simple design. In addition, it should be noted that this method is universal, that is, it can be applied to any type of aircraft, since it does not require the use of any special additional equipment.

Claims (4)

1. A method of preventing icing of structural elements of aircraft, in which structural elements of an aircraft in areas of risk of icing are heated to ice melting temperature t> 0 ° C, characterized in that the thermal energy necessary for heating is obtained by converting the kinetic energy of the on-going pressure head with a speed of M≥0.4 air, and then the received thermal energy is transferred to surface areas at risk of icing due to heat accumulation a. 2. The method according to claim 1, characterized in that for converting the kinetic energy of the incoming air velocity into the heat pressure in the frontal parts of the structural elements of the aircraft, for example in the frontal part of the wing, acoustic resonators are installed in which then high-frequency shock waves are generated, after which the blind ends of the resonators are heated to accumulate heat. 3. The method according to claim 1 or 2, characterized in that the acoustic resonators are installed along the front of the frontal parts of the structural elements of the aircraft. 4. The method according to any one of claims 1 to 3, characterized in that the acoustic resonators are made of highly conductive material, after which they are separated from each other by dividing elements.

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