RU2752446C1 - Air intake device of helicopter gas turbine engine - 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 in question 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. A positive effect is achieved by introducing an additional air purification system in the helicopter flight mode into the design of the fairing of the device (“fungal” DPD), operating on the principle of inertial separation of heavy particles on the frontal surface of the fairing from the incoming air flow, further collecting separated particles and removing them from the air flow directed to the engine. In addition, the separation of particles is used when they move near the peripheral zone of the fairing, for which they are given more favorable initial conditions for exiting the air flow heading into the air inlet of the device.EFFECT: invention achieves air purification from polluting particles in a wide range of their dispersed composition while maintaining the flight characteristics of the helicopter when operating under various operating modes and conditions.2 cl, 3 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.

In the course of long-term and widespread operation of this ROM, it revealed certain drawbacks, among which the inability of the ROM to purify the air in a helicopter flight mode in dusty air was most acutely manifested. 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 inflow to the ROM inlet, as well as the speed of movement of sand and dust particles do not ensure their separation into 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 possibility of separation and concentration of dust particles from the flow at the frontal 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.

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, an inlet annular opening is made in the fairing shell in its front expanding part, dividing the front part of the fairing into concentrically located peripheral and central elements. At the peripheral element, the front part of the shell is made in the form of the surface of a truncated circular cone. The central element is a shell in the form of a convex portion of a surface of revolution with a curved generatrix. These elements are installed one in relation to the other in such a way that the peripheral element protrudes forward relative to the central one. Between the elements, the aforementioned inlet annular opening in the fairing and the subsequent annular diffuser channel, which communicates the inner cavity of the fairing with the outer space of the air intake device, is formed. In the fairing of the device, one or more outlet pipes are also made, installed in the peripheral zone of the fairing, the pipes are installed in the radial direction, they pass through the shell of the fairing from its inner cavity into the outer air space. An inlet manifold is made at the end of the outlet pipe located in the inner cavity of the fairing, the part of the outlet pipe located outside in the external air flow has an oval cross-sectional shape and is oriented with its outlet opening to the rear radial-lateral side from the air intake opening of the device.

When a helicopter is flying in a polluted atmosphere, particles of sand and dust from the incoming air stream will come into contact with the surface of the central element of the fairing and follow along it in the near-wall layer, increasing the concentration with distance from the center of the stream. Due to the introduction of an inlet annular opening and an annular diffuser channel into the fairing design, the wall layer of air with sand and dust particles separated onto the fairing surface will enter the inner cavity of the fairing and then, under the action of excess pressure from the high-speed head of the incoming flow, will exit through the outlet pipes to the outer the space behind the air inlet of the unit. Another part of the foreign particles that have come into contact with the conical section of the surface of the peripheral element of the fairing acquire the initial conditions of motion that allow a large proportion of the largest and most abrasive particles to cross the layer of the air flow around the fairing and leave it before the flow enters the air intake opening of the device.

The essence of the claimed air intake device is illustrated in the diagrams - Fig. 1, 2, 3.

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, while the presented embodiment provides for the installation of two outlet pipes.

In the diagram of FIG. 3 shows a longitudinal section of an air intake device made in accordance with the present proposal, also shows air flow lines and trajectories of 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 the process of inertial separation of heavy particles of sand and dust, which takes place when the air flow around the fairing of the device.

To this end, in the fairing shell 4 of FIG. 2, an inlet annular opening 16 is made in its front expanding part 4 ', dividing the front part of the fairing into concentrically located peripheral 14 and central 14' elements, which are fastened into a single unit using spacers 15. At the peripheral element, the front part of the shell is made in the form of a surface of a truncated a round cone with a hole 17 facing the incoming air flow, while the transition point from the conical surface to the cylindrical section adjacent to the rear is made with a break in the contour. The inclination of the generatrix of the conical surface to the axis of the fairing is made at an angle a, the value of which is selected based on the condition of giving the dust particles initial conditions that provide them with a velocity vector sufficient for the particles to cross the air flow in the lateral direction. The central element 14 'is a shell in the form of a convex section of a surface of revolution with a curved generatrix (eg: ellipse, hyperbola, parabola). These elements are installed one in relation to the other in such a way that the peripheral element 14 projects forward relative to the central 14 '. An inlet annular opening 16 and a subsequent annular diffuser channel 16 'are formed between the elements, communicating the inner cavity 17' communicating the inner cavity 17 'of the fairing 4 with the outer space of the air intake device from the side of the oncoming air flow.

The fairing 4 of the device has one or more outlet pipes 18 installed in the peripheral zone of the fairing. The nozzles are installed in the radial direction, pass through the shell of the fairing from its inner cavity 17 'into the outer air space. An inlet manifold 18 'is made at the end of the outlet pipe 18 located in the inner cavity 17' of the fairing. The part of the outlet pipe 18, located outside in the external air flow, has an oval cross-sectional shape and is oriented with its outlet opening 18 '' towards the rear radial-lateral side from the air intake opening 8.

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 hole 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 paths 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 incident air flow following towards the engine from the central flow 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, basically 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, as a result of which there is no air purification.

The operation of the air intake device, made in accordance with the present proposal, in the modes of helicopter flight in polluted air is shown in FIG. 3. The air flow entering the air intake opening 8 of the device is limited by the air flow lines 20-21, while the trajectories of dust particles with dimensions of 5-40 mm moving in the flow are shown. The bulk of dust particles potentially capable of entering the air intake opening 8 is initially located in the zone between the air flow lines 20-21 (a certain fraction of particles also pass from the external flow zone between the flow lines 21-22). Dust particles from this zone, when moving near the surface of the fairing in a curved flow under the action of inertial forces, do not have time to follow the air flow lines, enter into contact with the surface of the central element 14 'of the fairing 4. Then the particles follow along the surface in the wall layer, increasing their concentration in the air as it approaches the inlet annular hole 16, pass through it into the annular diffuser channel 16 'and enter the inner cavity 17' of the fairing 4. From the inner cavity of the fairing, air with dust particles escapes under the action of excess pressure from the high-speed pressure of the incoming air flow along outlet nozzles 18 to the outer space in the rear zone from the air intake hole 8. When there is a lack of air pressure inside the fairing to increase the flow rate of air discharged to the outside, fans 19 are installed in the outlet nozzles 18, which are switched on in the operating mode if necessary. Another part of the foreign particles, moving mainly in the peripheral zone of the incident air flow, comes into contact with the conical surface of the peripheral element 14 'of the front part 4' of the fairing. As a result, solid particles acquire the initial conditions of motion, allowing a large proportion of the largest and most abrasive particles to cross the layer of air flow 20-21, enveloping the side fairing 4, and go beyond the flow before it enters the air intake opening 8 of the device - beyond the critical point K ' external streamline 21.

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 (2)

1. The air intake device of a helicopter gas turbine engine, which removes sand and dust particles from the air, including an entrance tunnel made in the form of a shell, having an inlet with a collector lip on the front side, a fairing representing a body of revolution having a front expanding and a rear the tapering part 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, the air intake annular opening of the device, as well as the flow channel with rotary and straight sections, into the composition the device also includes a separator, a branch pipe for removing dust from the separator and an ejector for suction of dust, characterized in that an inlet annular opening is made in the shell of the fairing in its front expanding part, dividing the front part of the fairing into concentrically located peripheral and central elements you, at the peripheral element, the front part of the shell is made in the form of the surface of a truncated circular cone, the central element is a shell in the form of a convex portion of the surface of revolution with a curved generatrix, these elements are installed one in relation to the other in such a way that the peripheral element protrudes forward relative to the central one, and between them is formed the above inlet annular opening and the subsequent annular diffuser channel, which communicates the inner cavity of the fairing with the outer space of the air intake device, and one or more outlet pipes are made in the fairing of the device, installed in the peripheral zone of the fairing, passing through the fairing shell from its the inner cavity into the external air space, an inlet manifold is made at the end of the outlet pipe located in the inner cavity of the fairing, the part of the outlet pipe located outside in the external air flow has an oval the shape of the cross-section and is oriented with its outlet opening to the rear radial-lateral side from the air intake opening of the device. 2. The air intake device of the helicopter gas turbine engine according to claim 1, characterized in that in the outlet nozzles located in the fairing of the device, an electrically driven fan is installed in the inlet of the nozzle, designed to suck air with dust from the inner cavity of the fairing and eject it into the outer space ...

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