RU2487059C1 - Aircraft fuel system - Google Patents

Abstract

FIELD: aircraft engineering.

SUBSTANCE: fuel system comprises fuel tank 1 with filler neck 2, drain system and engine feed pump 6 furnished with anti-dust filter 5 arranged at drain pipeline outlet to atmosphere 3. Aforesaid two-stage filter is composed of swirl generator 7 for air course cleaning and water separation and gauze filter 10 for air fine cleaning mounted at swirl generator cylindrical case outlet 8. Note here that swirl generator cylindrical case outlet 8 is covered by scroll channel 12 with open end for eject course cleaning products into atmosphere. Scroll channel outer pipe inclined edge 11 opposes incident flow in aircraft flight.

EFFECT: higher reliability of protection against ingress of dust and other particles in fuel.

2 cl, 5 dwg

Description

The invention relates to devices associated with the supply of fuel to the power plant of aircraft, and can be used in the drainage system of the fuel tank of a helicopter to prevent dust from entering the fuel through a drainage pipe connecting the fuel space of the tanks with the external atmosphere.

In known devices for supplying fuel to the power plant of aircraft (for example, “Designing the fuel systems of aircraft”, M .: “Mechanical Engineering”, 1975, p. 158-160, Fig. 6.2 and 6.3) drainage pipelines communicate directly with atmospheric air. However, in flight conditions in the immediate vicinity of the ground, dust or other foreign particles may get in together with air, which may cause a failure of the fuel system units inside the tank or in the drainage system itself.

Known designs of the cyclone type, designed to separate foreign particles from the air, for example, by swirling the air flow and dropping dust under the action of centrifugal forces to the walls of the cylindrical body (ed. St. USSR No. 270484, V04C 5/06, 1970). Known designs, including a spinning blade screw reflector mounted on the axis of the cylindrical body (patent RU No. 2181439, F02C 7/052, 2002).

The closest in design to the claimed device are direct-flow cyclones for cleaning outside air, which are part of the battery of cyclones for a dustproof device of the aircraft engine according to patent No. 2181439.

Such a direct-flow cyclone comprises a cylindrical body turning into a conical diffuser and a blade swirling “swirler” mounted in front of the body. In the outlet cross section of the housing there is a pipe for removing purified air, which forms an annular channel with a diffuser for the removal of separated dust into a dust collector. The cyclone is made with special geometric relationships of the device parameters.

The design and the claimed geometric relationships of the prototype reflect the features of its use as a basic element in the dustproof device of a helicopter power plant.

The disadvantage of the cyclone is that the size of the separated dust cannot be defined or specified, since the pile, fluff and other large, but close in specific gravity air, that is, light, but relatively large pollutants do not all have time to be removed, discarded by centrifugal forces and penetrate the channel of purified air.

The objective of the invention is to create a device that takes into account the design and operation of the fuel system and protects the fuel system of the aircraft from dust and other particles of a given size, defined, for example, by the gaps between the moving parts of the units, which, if released into the fuel, can lead to disruption to their work.

The problem is solved in that in the fuel system of an aircraft containing a fuel tank with a filler neck and a drainage system including a drain pipe and a drain valve, and an engine power pump, in accordance with the invention, a dust filter is installed at the outlet of the drain pipe to the atmosphere.

The dust filter is made in two stages: in the form of a vortex generator for rough air purification and moisture separation and a strainer installed opposite the output section of the vortex generator body, for fine air purification, while the output section of the vortex generator body is covered by a “snail” spiral channel with an open end for the emission of air with coarse products into the atmosphere, and an inclined section of the outer hull nozzle is located towards the incoming air flow during the flight of the aircraft Rata.

The presence of a filter at the outlet to the atmosphere of the drainage pipeline will prevent the ingress of dust, foreign particles of a given size and moisture into the fuel system of the aircraft. The implementation of the two-stage filter increases the purity of the purification of air coming from the atmosphere in the process of generating fuel from the tank. The selection of the parameters of the structural elements of the vortex generator and the selection of the sizes of the mesh filter openings allow the separation of dust and moisture, as well as the selection of the specified sizes of the particles detained by the filter. The specified particle sizes are determined by the values of the gaps between the moving elements of the units of the fuel system of the aircraft. Ultimately, a fuel system with such a dust and water filter in the drainage system of the fuel tank will increase the reliability of the aircraft as a whole.

A feature of the two-stage filter in the fuel system is the possibility of self-cleaning (regeneration or restoration of state) of the fine mesh filter in the parking lot of the aircraft, during the fueling process. Due to the sufficiently high flow rate of air displaced from the tank when refueling (significantly higher than when the fuel was consumed by the engine), the air displaced from the tank with fuel vapors blows and thus cleans the fine filter, throwing the filter back into the vortex generator foreign particles trapped in the atmosphere.

The presence of an external nozzle in front of the cylindrical part of the casing, in which the blades of the vortex generator are located, and the choice of the slope angle of its cut towards the incoming air flow make it possible to achieve sufficient efficiency of the vortex generator due to the pressure drop at the inlet and outlet of it.

The invention is illustrated by drawings, which depict:

figure 1 - diagram of the fuel system of the aircraft with the direction of air flow in the drainage system when fuel is generated in flight mode;

figure 2 is the same with the direction of air flow in the drainage system when refueling the tank with fuel on the ground;

figure 3 - dust and moisture protection filter, top view;

figure 4 is a section aa of figure 3;

figure 5 is a section bB of figure 4.

The fuel system of an aircraft, mainly a helicopter, contains (Fig. 1) a fuel tank 1 located under the floor of the passenger cabin with a fuel filler neck 2 and a drainage system including a pipe 3, a drain valve 4 and a dust filter 5 located at the outlet of the drain pipe 3 to the atmosphere . In the tank 1 there is a pump 6 for powering the helicopter engines.

Dust and moisture protection filter 5 of the drainage system is made of two stages (Fig.3, 4, 5). The first stage, rough cleaning, is a vortex generator (or ramjet cyclone) 7 and contains twisting blades 9 located in a cylindrical housing 8 (Fig. 4).

The second stage of the fine filter 5, made in the form of a strainer 10, which is located opposite the output section of the vortex generator 7 and is installed in the elbow of the drainage pipe 3 (figure 4).

The cylindrical body 8 of the vortex generator 7 has an outer pipe 11, a slice of which is located at an angle to the axis of the housing 8 and towards the incoming air flow during flight of the aircraft (figure 3).

The output section of the housing 8 is surrounded by an annular channel 12 in the form of a centrifugal scroll, open to the atmosphere for air removal with rough cleaning products (Figs. 4, 5).

The fuel system operates in flight as follows (figure 1). When the engines generate the fuel supplied by the pump 6, the outside air through the filter 5, the pipeline 3 and the drain valve 4 enters the fuel tank 1 at a speed equal to the speed of fuel consumption by the engine.

Getting through an inclined section of the outer pipe 11 on the swirl vanes 9, the air passes through the first stage of the filter 5. In this case, under the action of centrifugal force, moisture particles and dust are thrown to the periphery of the stream, to the walls of the housing 8 and together with the blown air stream enter the annular channel 12 and are thrown back into the atmosphere (into the rarefaction zone created by the incoming air flow in flight).

Passing through the first stage, the air stream passes further through the strainer 10 for fine cleaning into the pipeline 3 and through the drain valve 4 enters the fuel tank 1.

On the ground when refueling the aircraft with fuel (Fig. 2), air with fuel vapor displaced by the fuel entering the tank rushes into the atmosphere through pipeline 3 through the drain valve 4 and filter 5.

Since the speed of the air displaced from the tank by the fuel is significant (significantly exceeds the speed of the air drawn into the tank at the fuel consumption by the engine), the mesh filter 10 is automatically cleaned from the dust particles accumulated during the flight on its surface and emitted back to the atmosphere.

Claims (2)

1. The aircraft fuel system comprising a fuel tank with a filler neck and a drainage system including a drainage pipe with a drainage valve and an engine power pump, characterized in that a dust filter is installed at the outlet of the drainage pipe to the atmosphere. 2. The fuel system according to claim 1, characterized in that the dust filter is made in two stages: in the form of a vortex generator for rough air purification and moisture separation and a strainer installed opposite the output section of the vortex generator housing for fine air purification, while the output section the case of the vortex generator is covered by a spiral channel of the "snail" type with an open end for the release of air with coarse products into the atmosphere, and an inclined section of the outer pipe of the case is located towards him the air flow during the flight of the aircraft.

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