RU2825936C1 - Special air intake device with anti-icing system - Google Patents

Abstract

FIELD: ventilation and air conditioning.

SUBSTANCE: anti-icing system for air intake consists of crossed pylons and transverse sectors connecting pylons. Pylons and sectors are made of tightly connected panels (1–1, 2–1) and covers (1–2, 2–2), on inner surfaces of which there are inner profiled grooves, forming a network of channels. Cross-section of channels is variable. In places of channels turning, channel cross-section area increases. On panels (1–1, 2–1) and covers (1–2, 2–2) of pylons and sectors in all zones of front edges of washed surfaces there are calibrated holes, having an elongated shape, connected to a network of internal profiled channels.

EFFECT: high efficiency of preventing formation of ice on various surfaces in air channels.

9 cl, 6 dwg

Description

The invention relates to equipment for multi-mode aircraft, in particular to air intake devices, namely to anti-radar gratings, which are placed, as an option, in the air intakes of aircraft.

One of the main requirements for modern aircraft is a low level of visibility in the radar wavelength range. The total radar visibility of an aircraft in its forward hemisphere is largely determined by the contribution of the air intakes and engine inlets. And to reduce radar visibility, an anti-radar grid is installed in the air intake air duct.

For example, from the prior art (RU 2623031 C1) an air intake is known, in the air duct of which an anti-radar grid is installed to reduce radar visibility.

This source of information has been adopted in this application as the closest analogue.

When flown around by air in certain flight modes (most often when gaining altitude while passing through clouds), conditions (a combination of temperature and humidity) arise around the flown surfaces, in particular, anti-radar grids, that contribute to the formation of ice, which can subsequently break off and cause mechanical damage, leading to the failure of the object or its individual units and systems.

The most common areas for icing in flight are the leading edges of streamlined surfaces (wings, empennages, air intake entrances, etc.).

Icing also often occurs on the surface in a zone some distance away from the leading edges in the direction of flow. This phenomenon is called "barrier ice".

Depending on the shape of the edge, the nature of icing may differ in the shape of the growing ice. On sharp edges (typical for supersonic aircraft), ice build-up has a triangular shape in the edge cross-section. On rounded edges, icing begins around the edge rounding radius and is thickest at the point where the flow slows down.

Barrier ice forms on the surface in the form of a frozen surface droplet, which grows over time until it breaks off the surface. The layer of this ice has a bumpy shape (the thickness is uneven across the surface).

Thus, the authors of the claimed invention were faced with the task of eliminating the formation of ice on parts that are flown around by the air environment and have a low construction height, such as, in particular, on the surfaces of the parts of the air intake anti-radar grille.

The state of the art provides various options for attempts to eliminate the problem of ice formation on the streamlined surfaces of an aircraft.

For example, from source JPH 04110299 A, a system for preventing ice formation on the leading edge of the wing, which is streamlined by the air environment, is known, which is a system of tubes located in the internal space of the wing, which provide the supply of a hot medium (air) to the leading edge of the wing, providing its heating. At the same time, on the leading edge of the wing there are openings designed to release the hot medium onto the surface of the wing, also for its heating.

A similar technical solution is disclosed in the source RU 2736706 C2.

From source WO 2020160906 A1, an air intake is known that is equipped with an anti-icing system that prevents ice from forming on the leading edges of the air intake by forcibly circulating hot air in its interior. The hot air is released to the outside through at least one opening located further downstream from the leading edge of the air intake.

From the source US 2020346764 A1, an anti-icing air intake is also known, in which the formation of ice is prevented by a system of tubes inside the air intake body, through which a hot medium circulates.

However, none of the above systems can be installed in an anti-radar array, since the parts (pylons and sectors) of the anti-radar array itself are so thin that their internal space does not have the ability to accommodate tubes with a hot medium. And even if a system of tubes is placed inside a radar array, these tubes will be of such a small diameter that the air moving through them will cool down so quickly that it will not prevent the formation of ice on the leading edges and all surfaces of these parts.

In addition, no system or device is known from the prior art that could prevent ice formation using a hot medium on the surfaces of the anti-radar grid that are flown around by the air.

Thus, the technical result of the claimed invention is to increase the efficiency of preventing ice formation on the surfaces of the anti-radar grid or other thin-walled structures placed in air ducts that are flown around by the environment.

The technical result achieved is fully achieved by the set of features of the invention declared in the independent claim.

An additional technical result provided by the claimed invention is the production of a grille with an anti-icing system as a prefabricated unit, which simplifies its installation and manufacture.

In completing the assigned task, the problem of using power fasteners connecting thin-walled structures without protruding into the air flow was also solved.

The anti-icing system for the air intake consists of crossed pylons and transverse sectors connecting the pylons, forming a single rigid hollow contour, where the pylons and sectors are made of hermetically connected panels and covers, on the inner surfaces of which internal profiled grooves are made, corresponding to each other, forming a single network of internal profiled channels, designed to ensure the supply of a heating substance to the zones requiring heating. The cross-section of the channels is variable. In places where the channels turn, including in places where the pylons and sectors are connected, the cross-sectional area of the channels increases. On the panels and covers of the pylons and sectors in all areas of the leading edges of the washed surfaces, there are calibrated holes of an elongated shape, connected to the network of internal profiled channels. The holes are located along the washed edges with their long sides.

The holes are located in a line along the washed edges at a distance from each other equal to the length of the holes themselves.

The holes are directed towards the side surfaces of the parts with their minimum proximity to the front edges.

At the joints of the pylons and sectors, removable connectors with channels are installed that correspond to the channels on the joint surfaces.

The panels and covers of the pylons and sectors are connected using sealing glue and riveted joints.

The panels and covers of the pylons and sectors are made of heat-conducting material.

The pylons and sectors are connected to each other by a power fastener consisting of a bolt and a nut that does not protrude into the air flow, while the bolt is made hollow and flared in the nut, and the flare is obtained by screwing a nut onto the bolt.

The design of the pylons and sectors uses a radial shape of air ducts.

The design of the inlet channels of the sector coolant in the zones of transition of flows from the pylon channels to the sector channels at a right angle is divided into two receiving channels in the sector.

The claimed invention is further explained in more detail by drawings, in which:

Fig. 1 - fragment of the anti-radar grid placed in the air duct (front view).

Fig. 2 - typical design of anti-radar grid pylons.

Fig. 3 - typical design of anti-radar grid sectors.

Fig. 4 - profile of the areas of the coolant transfer channels from the pylons to the sectors on the anti-radar grids.

Fig. 5 - profile of coolant flow from pylons to sectors on anti-radar grids.

Fig. 6 - installation of power fasteners for attaching sectors to pylons.

In the attached drawings the following positions are indicated:

1 - pylons,

1-1 - pylon panel,

1-2 - pylon cover,

2 - sectors,

2-1 - sector panel,

2-2 - sector cover,

3 - bracket for fastening pylons in the air duct,

4 - zone of coolant outlet from the pylon to the sectors,

4-1 - channels for coolant in the pylon,

5 - zone of coolant entry into sectors,

5-1 - channels for coolant in sectors,

6 - heating zone,

7 - profiled holes of the pylon for the discharge of the coolant,

8 - profiled openings of sectors for the discharge of coolant,

9 - special bolt for fastening thin-walled bodies,

9-1 - bolt,

9-2 - nut,

10 - leading edge of the air duct,

11 - coolant supply,

X - theoretical contour of the air duct.

The declared anti-icing system of the air intake consists of two intersecting pylons (1), between the parts of which transverse sectors (2) are installed. The pylons (1) in turn are connected to the air duct through hollow brackets (3), supplying the coolant (hot air) to the entire structure, for example, the anti-radar grid. The anti-radar grid is a set of channels (4-1, 5-1), located inside the pylons (1) and sectors (2), for supplying the coolant to the zones of probable icing of the washed surface with the discharge of the coolant through profiled openings (7, 8) onto the surface. Each of the pylons (1) and sectors (2) is made of a panel (1-1, 2-1) and a cover (1-2, 2-2), which are connected to each other using glue and riveted joints. On the inner surfaces of the panels (1-1, 2-1) there are internal profiled channels which correspond to the internal profiled channels on the inner surfaces of the covers (1-2, 2-2), which together form single internal profiled channels intended to ensure the supply of a heating substance (heat carrier) to the zones requiring heating. On the panels (1-1, 2-1) and covers (1-2, 2-2) of the pylons (1) and sectors (2) in the zones of the most probable accumulation of ice (the front edges of the washed surfaces, and the zone equidistant from the front edges at a distance of about 150 mm in the direction of the washing flow) there are profiled openings (7, 8), which are made elongated and are located along the washed edges with their long sides. The holes (7, 8) are located along the line along the washed edges at a distance from each other equal to the length of the holes (7, 8) themselves, which ensures maximum efficiency of heating the surface and also eliminates the reduction in the rigidity of the structure. This ensures the prevention of ice accumulation on the front edges of the washed surface of the grate and in the zone of formation of "barrier ice". The panels (1-1, 2-1) and covers (1-2, 2-2) are made of heat-conducting material to ensure maximum efficiency of heat transfer from the heating substance to the outer surface of the grate.

Pylons (1) and sectors (2) form a single device - an anti-radar grid, inside which there is an internal single branched network of channels for the heating substance. The cross-sectional area of the channels changes depending on the estimated flow rate of the heating substance in them. At the points where the channels turn (including at the joints of the pylons and sectors), the cross-sectional area increases to ensure minimal deviation in pressure and flow rate of the heating substance.

At the joints of the assembly units (pylons and sectors), as well as at the installation points of the anti-radar grid on the base surface, removable connectors are installed in brackets (3) using mechanical connections to ensure installation, dismantling and maintenance at the stages of primary assembly and operation. Mechanical connections of the design parts provide for the possibility of joint cutting of holes during primary assembly. This ensures compensation for deviations in the shape and location of the surfaces of the assembled product from the specified contour; at the connectors, a reliable fit of adjacent surfaces is ensured to achieve the required level of tightness of the structure and the accuracy of matching the internal contours of the channels on the adjacent surfaces.

Thus, the coolant (hot air) enters the network of channels of the anti-radar grate under pressure and spreads along it due to the variable cross-section, providing the required coolant pressure and heating the entire surface of the grate, and upon reaching the openings (7, 8) comes out, preventing the formation of “barrier ice”.

In the design of pylons and sectors, the geometric parameters of the leading edges of the pylon sections are optimized with the integration of air discharge holes as close as possible to the leading edge of this section. This geometric optimization allows heating the entire leading edge of the pylons, sectors and brackets of the anti-radar grid suspension while having a safe and durable design, as well as protecting the surface of the pylons and brackets from barrier ice.

In the design of the pylons, sectors and suspension brackets, the air discharge holes are directed only at the side surfaces of the parts, and not towards the air velocity pressure, which in this design does not clog the outlet holes. This technical solution allows heating all the front edges of the pylons, sectors and suspension brackets of the anti-radar grid, as well as protecting all surfaces of the pylons, sectors and suspension brackets from barrier ice. Making these holes in the direct direction to the oncoming air flow at high speeds is ineffective, since the flow is blocked in the air outlet holes, and the system becomes impermeable and, as a result, ineffective.

The design of the inlet channels of the sector coolant, in the areas of transition of flows from the pylon channels to the sector channels at a right angle, is not made as a single channel, but is divided into two receiving channels in the sector. This solution allows to increase the length of the perimeter of the inlet channels of the sectors, which, with their low construction height, allows to preserve and increase the total area of the flow section in comparison with the flow section of the pylon supplying the coolant to the sectors of the anti-radar grid. This solution also allows to install additional attachment points connecting the pylons and sectors in the areas of installation of external aerodynamic profiled fairings of the channels (4-1, 5-1).

The sectors are secured to the pylons using a special power fastener - a special bolt for fastening thin-walled bodies (9), which does not protrude beyond the dimensions of the pylon thickness, which in turn prevents barrier ice from accumulating in these areas, since the outer surface of the pylons and sectors always remains without protruding connections, as could be the case with a conventional classic connection of a countersunk bolt with a protruding nut. Protection against loosening of this type of connection is applied in the form of pressing the hollow part of the bolt into the grooves of a special nut, which, in addition to the use of an adhesive type of locking for this type of connection, increases the additional reliability of this connection from loosening and, as a result, additional protection of the power plant (engine) from foreign objects in the form of fasteners from the design of the anti-icing system.

Claims (9)

1. An anti-icing system for an air intake consisting of crossed pylons and transverse sectors connecting the pylons, forming a single rigid hollow contour, where the pylons and sectors are made of hermetically connected panels and covers, on the inner surfaces of which internal profiled grooves are made, corresponding to each other, forming a single network of internal profiled channels, intended to ensure the supply of a heating substance to areas requiring heating, wherein the cross-section of the channels is variable, and at the places where the channels turn, including at the joints of the pylons and sectors, the cross-sectional area of the channels increases, and on the panels and covers of the pylons and sectors in all areas of the leading edges of the washed surfaces there are calibrated openings having an elongated shape, connected to the network of internal profiled channels, wherein the openings are located along the washed edges with their long sides. 2. An anti-icing system for an air intake according to paragraph 1, characterized in that the openings are located along a line along the washed edges at a distance from each other equal to the length of the openings themselves. 3. An anti-icing system for an air intake according to paragraph 1, characterized in that the openings are directed toward the side surfaces of the parts with their minimum proximity to the leading edges. 4. An anti-icing system for an air intake according to paragraph 1, characterized in that removable connectors with channels corresponding to the channels on the articulated surfaces are installed at the joints of the pylons and sectors. 5. An anti-icing system for an air intake according to paragraph 1, characterized in that the panels and covers of the pylons and sectors are connected using sealing glue and riveted joints. 6. An anti-icing system for an air intake according to paragraph 1, characterized in that the panels and covers of the pylons and sectors are made of a heat-conducting material. 7. An anti-icing system for an air intake according to paragraph 1, characterized in that the pylons and sectors are connected to each other by a power fastener consisting of a bolt and a nut that does not protrude into the air flow, while the bolt is made hollow and flared in the nut. 8. An anti-icing system for an air intake according to paragraph 1, characterized in that the design of the pylons and sectors uses a radial shape of air ducts. 9. An anti-icing system for an air intake according to paragraph 1, characterized in that the design of the inlet channels of the sector coolant in the areas of transition of flows from the pylon channels to the sector channels is divided at a right angle into two receiving channels in the sector.