RU2752445C1 - Air intake device of helicopter gas turbine engine that removes sand and dust particles from air - Google Patents

Abstract

FIELD: aircraft engineering.SUBSTANCE: air intake device of a helicopter gas turbine engine is proposed, which removes sand and dust particles from the air. A feature of the device in comparison with the existing domestic dust-proof device (DPD) of the “fungal” type is that the device under consideration cleans the air not only in the modes of moving the helicopter with low speeds near the ground (taxiing, hovering, take-off and landing), but also when flying at cruising speed in conditions of dust-polluted air.EFFECT: positive effect is achieved by introducing a screen into the structure of the fairing of the device (“fungal” DPD), which serves to collect and remove dust-enriched air from the central zone of the fairing and then clean it before entering the engine. In addition, the specified screen is used to purify the air entering the air intake of the device from the peripheral flow zone, due to the reflection of particles from the conical surface of the screen in the lateral directions. Also, the positive side of the proposed device is the preservation of flight-technical and operational-technical characteristics at the same level and the possibility of updating the DPD under operating conditions.1 cl, 2 dwg

Description

The invention relates to the field of aircraft construction, specifically to air intake devices of helicopter gas turbine engines (GTE), which remove particles of sand and dust from the air. The ingress of these particles into the gas-air path of the engine in large quantities leads to erosive wear of the engine compressor blades, a decrease in engine power and reserves of its gas-dynamic stability (to surge), as well as to a decrease in the engine resource, an increase in the cost of GTE repair, a decrease in the operational manufacturability of both the engine and the helicopter. , to a decrease in flight safety, a deterioration in fuel efficiency, etc.

Known methods and devices designed to solve this problem, their descriptions are given in patents [1, 2, 3,], as well as in [4]. The last of the analogous devices [4] dust-proof device (ROM) has found wide application in the domestic helicopter industry and in operation.

The proposed invention is functionally and structurally based to a large extent on the above-mentioned ROM, which is adopted as a prototype.

With the said prototype device, as the areas of application of helicopters expanded, the situation with the possibility of operating helicopters in a helicopter flight mode in dusty air became aggravated due to the lack of air purification in this mode in this type of ROM. This circumstance leads to all the above-described consequences, the main of which is a reduction in the service life of the engine. The reasons for the lack of air purification in the ROM in the helicopter flight mode are the following factors:

- the design of the specified ROM prototype does not provide for the performance of the air purification function in the helicopter flight mode (but only during hovering, takeoff and landing), respectively, the direction of air flow to the ROM inlet, as well as the speed of movement of sand and dust particles do not ensure their separation when the entrance to the ROM;

- during a helicopter flight, dust particles contained in the air flow around the mushroom-shaped fairing of the device are separated from the flow onto the surface of the fairing of the ROM, but are not removed from the air flow, but pass into the air intake opening of the device, and then into the engine.

The technical problem to be solved by the present invention is to obtain an air intake device capable of performing the function of cleaning air from sand and dust particles not only in take-off and landing modes, hovering and moving at low speed (which is the case with the prototype ROM), but and in a helicopter flight mode in a dusty atmosphere.

The solution to this problem provides:

- air purification from a significant proportion of the largest fractions of sand and dust particles in the horizontal flight mode of the helicopter;

- increasing the service life of engines when operating in dusty air under wide operating conditions, improving the characteristics of the helicopter, if possible, using it in places with increased dustiness of the airspace.

The following factors contribute to the successful solution of the task:

- the presence of a fairing in the device, which prevents the direct passage of contaminated air into the GTE inlet;

- the presence in the incoming air flow in front of the fairing of a section with curved lines of air flow in the helicopter flight mode and, accordingly, the presence of separation and concentration of yellow particles from the flow at the front surface of the fairing;

- the possibility of using the existing design of the "fungal" ROM as a basis for modernization and obtaining air purification in flight mode; the economic feasibility of the proposed invention is obvious, since the cost of its implementation is significantly lower than the possible economic effect.

The essence of the proposed air intake device for a helicopter gas turbine engine, which removes sand and dust particles from the air during the operation of the helicopter in flight, is as follows. By its design, the proposed air intake device basically repeats the original design of the prototype ROM [4]. It includes an entrance tunnel made in the form of a shell with an inlet with a collector lip on the front side.

In the entrance tunnel from the side of the inlet, a fairing is installed, which is a body of revolution having a front expanding and a rear converging part with the largest cross-sectional area in the midsection of the fairing. The fairing is fixed on the tunnel coaxially and forms, together with it, the air intake annular opening of the device, as well as the flow channel with the rotary and straight sections. The device also includes: a separator, a branch pipe for removing dust from the separator and an ejector for suction of dust concentrate. This initial design of the prototype air intake device (ROM), which cleans the air only at low speeds of movement of the helicopter, in the proposed invention is equipped with an additional system for collecting and removing particles of sand and dust from the air supplied to the helicopter GTE in the helicopter flight mode in a polluted atmosphere. For this purpose, a screen is installed on the fairing, made in the form of a shell having a front opening with a diameter size less than the diameter of the midsection of the fairing, the rear opening of the shell having a diameter equal to the diameter of the midsection. The screen is installed and fixed on the front part of the fairing, in its peripheral zone with a gap, so that an annular channel is formed between the surfaces of the fairing and the screen. The inlet to the specified channel is formed by the space between the edge of the front opening of the screen shell and the surface of the fairing, the edge of the rear opening of the shell adjoins the fairing in the zone of its midsection. In the shell of the front part of the fairing, in its peripheral zone, a through hole or a group of holes is made, communicating the inner cavity of the fairing through the annular channel and the inlet with the outer space of the air intake device from the side of the incoming air flow. In the rear part of the fairing, an outlet is made, located around the dust removal pipe passing through the fairing, which communicates the inner cavity of the fairing with the space of the flow channel of the tunnel in the zone between its rotary and straight sections.

Due to the above-described design of the air intake device, when a helicopter is flying in a polluted atmosphere, sand and dust particles that have entered into interaction with the frontal surface of the fairing and located in the near-wall layer of the fairing will pass into the inlet formed by the leading edge of the screen with the surface of the front part of the fairing, move through the inner cavity of the fairing and out of it into the air flow inside the tunnel before entering the separator. After passing through the separator, the air purified from sand and dust particles enters the gas turbine engine, and the dust concentrate is removed from the device through the dust removal pipe using an ejector. In addition, in the proposed air intake device, the front area of the screen is made in the form of a conical surface and is used as a reflector of sand and dust particles to the side of the flow. By providing the particles with more favorable initial conditions, coarse particles are discharged into the external air stream, increasing the overall efficiency of air purification in the device.

The essence of the claimed air intake device is illustrated in the diagrams - Fig. 12.

In the diagram of FIG. 1 shows a longitudinal section of the prototype air intake device [4], its main elements, air flow lines at the inlet to the device in hovering and horizontal flight modes; the trajectories of sand and dust particles are also shown.

In the diagram of FIG. 2 shows a longitudinal section of an air intake device made in accordance with the present proposal, and also shows air flow lines and trajectories of sand and dust particles during a helicopter flight in polluted air.

Air Intake Device FIG. 1 includes an entrance tunnel 1, made in the form of a shell 2, having an inlet opening with a collector lip 3 on the front side. From the front side of the entrance tunnel 1, a fairing 4 is installed, which is a body of revolution having a front expanding part 4 'and a rear tapering part 4 '', between the specified parts of the fairing is the largest diameter cross-section of the fairing M-M - midsection. The fairing 4 is attached to the entrance tunnel 1 coaxially and forms, together with the tunnel, an annular air intake hole 8 and a flow channel 9 with a turning section 9 'and a straight section 9' '. The rear flange connects the entrance tunnel to the helicopter GTE 13. The air intake device also includes: separator 5, line for removing dust from separator 5 - straight pipe 6, rotary pipe 6 'and ejector for suction of dust concentrate 7.

The separator 5 is a cone-shaped louvred lattice, consisting of a set of sequentially located reflective annular elements 5 'and a support 5' ', between which there are formed bypass slotted channels 11, which communicate the inner cavity of the separator with the space of the flow channel 9. The separator is attached with its rear support 5' ' to the central flange of the helicopter engine 13. The dust removal branch pipe 6 is located between the rear support 5 "of the separator and the fairing 4 by means of a rotary branch pipe 6 '. The dust extraction line is connected to the dust concentrate suction ejector 7.

In the proposed air intake device FIG. 2, an additional system for collecting and removing sand and dust particles from the air supplied to the helicopter GTE in the helicopter flight mode in a polluted atmosphere is made. The operation of the system is based on the use of processes of inertial separation of heavy particles of sand and dust, which take place when the air flow around the fairing of the device. For this purpose, a screen 14 is installed on the fairing 4, made in the form of a shell having a front opening 15 with a diameter size less than the diameter of the midsection MM of the fairing 4. The rear opening of the screen shell has a diameter equal to the diameter of the midsection. The screen is installed and fixed on the front part 4 'of the fairing 4, in its peripheral zone with a gap from the surface of the fairing, so that an annular channel 16 is formed between the surfaces of the fairing and the screen. surface of the front part of the fairing 4 '. With the edge of the rear opening, the screen adjoins the fairing 4 in the zone of its midsection MM. An opening 18 (or a group of holes) is made in the shell of the front part 4 'of the fairing, in its peripheral zone, which communicates the inner cavity of the fairing through the annular channel 16 and the inlet 17 with the outer space of the air intake from the side of the incoming air flow. In the rear part of the fairing 4 '' in the place of passage through its shell of the dust removal pipe 6, an outlet-19 is made, which communicates the inner cavity of the fairing 4 with the space of the flow channel 9 FIG. 1 of the entrance tunnel 1, in the area in front of the entrance opening 10 'to the separator 5. The front portion of the screen 14 FIG. 2 is made in the form of a belt 14 'having a conical surface, while the generatrix of the cone is located to the axis of the fairing 4 at an angle α, which provides the necessary conditions for the reflection of sand and dust particles from the specified conical surface and their subsequent exit in the lateral direction from the air flow limited streamlines 20-21 moving to the air intake 8 of the device. The place of transition from the front conical section of the screen-belt 14 'to the subsequent rear section 14' 'is made with a sharp break in the contour of the screen - with a small transition radius.

The air intake device works as follows. When the helicopter is operating at low speeds of movement (taxiing, takeoff and landing, hovering, etc.), the pattern of the air flow lines flowing to the air intake opening 8 - Fig. 1 is shown by dashed lines 8 '. On the curved section 9 'of the annular channel 9, inertial separation of dust particles is carried out, which move along curved trajectories and enter the inlet 10' of the separator 5. The direction of movement of air and dust is shown by arrows 12 - clean air, 12 '- air with dust, 12' '- dust concentrate. In the separator, a further stepwise concentration of the polluting material in the air continues, the dust concentrate 12 '' enters through the dust removal line (branch pipes 6 and 6 ') into the ejector 7, from where it is discharged from the device into the surrounding space. The air, cleaned of pollutants in the curved section 9 ', enters the annular passage 10 and along the straight section 9' 'of the flow channel 9 passes into the inlet of the helicopter GTE 13. Part of the air 12 purified in the separator 5 also enters the bypass slotted ducts 11 into the flow channel 9 and into the engine. In the manner described above, both the prototype air intake device ("fungal" ROM) and the proposed device operate in the helicopter operating modes with a low speed of movement.

When the helicopter is operating at flight speeds, the pattern of the air stream lines flowing to the air intake opening 8 of the prototype device is shown in FIG. 1 by dashed lines 20 and 21, which delimit a part of the oncoming air flow following to the engine from the central zone. The specified part of the flow is additionally supplied with sand and dust particles from the side zone of the flow between the streamlines 21-22. Points K and K 'are the critical points of streamlines 20, 21. The largest fraction of particles from the incident flow comes from the central zone, while the bulk of coarse (most abrasive) particles comes into contact with the surface of the fairing 4. After collision with the surface, the particles follow along it and are concentrated in the parietal layer. With the original geometry of the fairing, due to the smooth contour lines in the zone of the largest diametrical dimensions (midship), the dust particles do not have any significant reserves of energy of the lateral component of the speed of movement for crossing the air flow limited by the streamline 21. As a result, they pass with the flow into the air intake hole 8 device - FIG. 1, generally do not enter the inlet 10 'of the separator 5, but pass through the opening 10 directly into the inlet of the gas turbine engine 13.

During operation of the air intake device equipped with a fairing made in accordance with the invention, the pattern of movement of dust particles in flight mode changes - Fig. 2. Firstly, particles of sand and dust moving along the surface of the fairing in the near-wall layer of its central zone enter the inlet 17, bordering the frontal area of the fairing, while the edge of the front opening 15 of the screen 14 acts as a flow separator, separating from the general flow 20-21 side outlet, entering through the annular channel 16 opening 18 into the inner cavity of the fairing 4. Further, the air enriched with pollutants leaves the fairing through the opening 19, enters the inlet 10 'of the separator 5, in which it is cleaned in the normal operating mode of the air cleaning device , while in the flight mode of the helicopter, the dust suction ejector in the device is on. Secondly, due to the implementation in the front part of the screen 14 of a section with a conical surface 14 ', the particles of sand and dust entering into contact with the specified surface acquire a significant value of the radial component of the speed of movement. After entering the lateral zone 20-21 of the air flow, the particles have a significant margin of inertia to overcome the narrowest section of the lateral flow (in the midship zone) and go beyond it - streamline 21. FIG. 2 conventionally shows the trajectories of motion of particles of different sizes (5-40 mm) after their exit in the place of the bend of the fairing contour.

As a result of using the proposed air intake device, a significant proportion of coarse dust fractions can be effectively removed from the air entering a helicopter GTE in a helicopter flight mode in a polluted atmosphere.

Sources of information

1. US patent No. 4881367, 1989 F02C 3/32.

2. US patent No. 3513691, 1970 F02C 3/32.

3. US patent No. 4493185, 1985 F04D 29/70.

4. V.A. Dmitriev, V.M. Zanko, N.P. Kalinin, A.I. Krivko Helicopter Mi-8 MTV, Moscow, Transport 1995 (p. 164, Dust protection device).

Claims (1)

The air intake device of a helicopter gas turbine engine, which removes sand and dust particles from the air, includes an entrance tunnel made in the form of a shell, having an inlet with a collector lip on the front side, a fairing, which is a body of revolution with a front expanding and rear tapering parts and the largest diameter cross-section of the fairing, midsection, installed in the inlet tunnel from the side of its inlet opening, attached to the tunnel coaxially and forming, together with the tunnel, an air intake annular opening of the device, as well as a flow channel with rotary and straight sections, the device includes also a separator, a branch pipe for removing dust from the separator and a dust suction ejector, characterized in that a screen is installed on the fairing, made in the form of a shell having a front opening with a diametrical size less than the diameter of the midsection of the fairing and a rear opening with a diametrical size ohm equal to the diameter of the midsection, the screen is installed on the front part of the fairing in its peripheral zone with a gap, so that an annular channel is formed between the surfaces of the fairing and the screen, having an inlet formed by the edge of the front opening of the screen and the surface of the fairing, the edge of its rear opening adjoins the screen to the fairing in the zone of its midsection, in the shell of the front part of the fairing in its peripheral zone, a through hole or a group of holes is made, communicating the inner cavity of the fairing through the annular channel and its inlet with the outer space of the air intake device from the side of the incoming air flow, in the rear part of the fairing an outlet is made, located around the dust exhaust pipe passing through the fairing, which communicates the inner cavity of the fairing with the space of the flow channel of the tunnel in the area in front of the air inlet into the separator, the front section of the screen is made in the form of a belt with a conical surface surface, the generatrix of which is located to the axis of the fairing at an angle that provides conditions for the reflection of sand and dust particles from the specified conical surface and their subsequent exit in the lateral direction from the air flow moving to the air intake opening of the device, while the transition from the conical section of the screen to the subsequent rear the section adjacent to the midsection of the fairing is made with a break in the contour of the screen.

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