DE2718643A1 - FAN ELECTRICITY REVERSING SYSTEM WITHOUT FLAPS FOR JETS - Google Patents

Description

Dr. rer. near Horst pupil PATENT ADVOCATE

6000 Frankfurt / Main 1 26.1.19 Kaiserstrasse 41 WK / - / Rg

Telephone (0611) 235555 2718643 Telex: 04-16759 mapat d

Postal check account ι 282420-402 Frankfurt / M.

Bank account: 225/0389

Deutsche Bank AG, Frankfurt / M.

4237-13DV-645O

GENERAL ELECTRIC COMPANY

1 River Road SCHENECTADY, N.Y./U.S.A.

Fan flow reversal system without flaps for jet engines

7098 45/1001

The invention relates to a thrust reversing system and in particular a Schul.umkehrsystem which can be used to a particular extent for fan engines of sheath flow type or dual flow or bypass type.

With the introduction of the engines, with a high bypass ratio it became necessary to provide a mechanism for reversing the flow of working medium through the generally annular To create cross-section of the bypass channel. Many reversers of this type have been used for prior art engines proposed with a high bypass ratio. These prior art inverters generally included Barriers, inflatable membrane devices or other complicated mechanisms for blocking the bypass flow and to reverse its direction of discharge. However, these prior systems were because of their complexity relatively heavy, expensive to manufacture, and difficult to maintain.

It is, therefore, the primary object of the present invention to provide a thrust reversing mechanism for a turbofan gas turbine engine to create which is simply constructed, easy and economical to manufacture, reliable is and can be easily serviced and continues to be easy to adjust thrust because of its simplicity of the flight can be set up.

According to the invention, a gas turbine engine includes a outer nacelle or engine cowling, which from a core engine housing to form an intermediate one Bypass channel or sheath flow channel is spaced. The gondola contains a fixed front part and a sliding rear part. The inner canal

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wall, as it is formed by the rear part of the nacelle, has such a position with respect to the engine housing, that with full displacement of the rear part of the nacelle downstream with respect to the flow of the working medium the inner wall of the rear part of the nacelle rests against the engine housing and thereby the bypass channel shut off. In its extreme downstream position, the rear part of the gondola encloses a ring of fixed staggered structures Reversing guide vanes, which are firmly attached to the front nacelle part in such a position that they are in Fluid communication with the bypass channel are when the rear part of the nacelle is displaced downstream. Adjusting devices are provided for moving the rear part of the pod. When a reversal of direction the thrust of the engine is desired, then the actuating device is used for full displacement of the rear part of the nacelle in the downstream direction with respect to the working medium. This causes the rearward The nacelle part rests against the engine housing and thereby blocks the bypass channel. To the extreme downstream located end of the rear part of the nacelle, an annular seal can be used to prevent gas passage during this mode of operation. At the same time, the staggered guide vanes are used to deflect the flow exposed and brought into fluid communication with the bypass channel so that the flow in the bypass channel is ejected through the guide vanes in the downstream direction and thereby a thrust in the opposite direction Direction is generated.

Because of the simplicity of construction, the reversing mechanism for the sheath flow or fan flow results in accordance with the invention several advantages over previously known mechanisms

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of this type. Since the reversing device according to the invention only uses a single sliding part and no locking flaps, inflatable membranes or other devices Used in this way to block the bypass channel, it is significantly easier to manufacture and maintain, and it is more reliable and lighter than the complicated reversing mechanisms of the prior art. Farther In the case of the reversing device according to the invention, in the position for forward thrust, the result is a significantly lower thrust Leakage than in previously known thrust reversers. The reason for this is that the leakage of connecting rods, Barrier doors, inflatable membranes and actuators of the prior art reversers eliminated became. The efficiency of the thrust reverser of the invention in the thrust reverse position is also considerably better than the degree of efficiency that can be achieved with previously known thrust reversers can. For the thrust reverser of the invention, only a single sealing ring is required to the To block cross-section of the outlet nozzle of the bypass channel. The leakage from this single seal is significant less than the combined leakage of the many seals for barrier doors and similar devices like them must be used in the previously known thrust reverser systems. Furthermore, the result is a smoother flow surface as a result of the lack of connecting rods, locking flaps and actuators, a reduction in aerodynamic Frictional losses in flight.

Another advantage of the thrust reverser is that it is lightweight because of the simplicity of its construction can be set up for the thrust adjustment during flight. For example, a control system for the actuating equipment

709845/1001

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Device can be provided to adjust the position of the rear part of the pod depending on the desired thrust to steer in the forward direction and thereby create a change in thrust during flight. In this way the flow through the bypass channel can be divided between the staggered deflection vane and the Outlet nozzle of the bypass channel. Prior art control systems which have been used to control the angular adjustment of the inlet guide vanes and the cross section of the exhaust nozzle can be used for this purpose. A control system of this type is disclosed, for example, in U.S. Patent No. 2,431,168.

Another advantage of the thrust reversing mechanism without flaps according to the invention is that its simplicity results in a larger surface area for acoustic improvement measures on the fan duct. The bypass channels for engines with conventional fan reverse flow mechanisms have a low ratio of surface equipped with acoustic devices to the actually existing spatial surface, because of the length of the excluded areas which are required for the flap edges, connecting rods and other mechanisms as used in the reversing device to be used. The reversing device according to the invention does not have these disruptive parts and therefore offers a larger area for acoustic treatment of the inside and outside of the fan duct. Furthermore, the

Contact surface for the movable rear gondola section and the enlarged curvature required for this of the engine bypass channel already has significantly better sound absorption than the previously known bypass channels with less curvature.

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A better understanding of the invention emerges from the following description, for example men in connection with the illustrations.

the following description of exemplary embodiments

FIG. 1 shows a sectional view of a sheath flow gas turbine with a thrust reverser device according to the invention.

FIG. 2 shows a partial view of the gas turbine engine according to FIG. 1 and particularly shows the thrust reverser according to the invention in an operating mode for thrust in the forward direction.

FIG. 3 is a view of the thrust reverser according to FIG. 2 during operation with thrust in the reverse direction.

FIG. 4 shows a sectional view along the line 4-4 of FIG.

Figure 1 shows a gas turbine engine of the bypass type or sheath flow containing the thrust reversing mechanism according to the invention. It should be noted that below the invention using the example of the gas turbine engine with a forward fan and a high bypass ratio is described, but the invention can be applied in the same way to any bypass engine can, including those engines with a fan located at the rear and with a fan for generating thrust in cruise.

FIG. 1 shows a gas turbine engine 1o with a shorter outer nacelle 12 spaced apart from one generally

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core engine shown at 14, which is supported by a fairing or casing 16 to form an intermediate Bypass channel 24 is enclosed. The outer nacelle 12 extends upstream from the core engine 14 to Formation of an inlet 18 for the engine. A fan 2o for compressing the inlet air flow is arranged in the inlet. Part of the coming from the blower or fan Exiting air flow is directed into the core engine 14 and the remaining part is through the bypass duct released into the environment, which is formed between the nacelle 12 and the engine housing 16. That downstream located end of the nacelle 12 ends at a small distance downstream from the inlet of the core engine 14 to Formation of the outflow nozzle 26 of the bypass channel. The channel is curved and generally S-shaped so that the Fan flow is initially directed radially outwards and is then deflected so that it comes out of the nozzle 26 for example flows out tangentially to the engine housing 16. The gondola 12 includes a front part 3o that seals on a rear part 28 is applied. The rear gondola part 28 is relative to the front gondola part 3o slidably attached, as can best be seen from FIGS. 2 and 3. A variety of at the scope spaced actuators 31 is attached to the front nacelle part 3o and has control arms 33 for the displacement of the rear gondola part 28, which are in drive connection therewith. In order to reduce the inlet noise, the inner and outer surfaces of the nacelle 12 can be coated with a sound absorbent Cladding 35 to be fitted; alternatively, the entire gondola 12 can be constructed from a sound-absorbing material (not shown).

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Reference is now made to Figures 2 and 3, which show details of the thrust reverser according to the invention. The rear part of the gondola 28 encloses in its extreme position upstream a ring of fixed staggered turning guide vanes 34, which in an annular bore 37 protrude in the rear part of the nacelle. The rear nacelle part 28 is sliding supported on a plurality of circumferentially spaced slide rails 32 carried by the cascade ring 34 will. At its upstream end, the cascade ring 34 can be rigidly connected to the front nacelle part 3o. A suitable seal 36 can be provided be to seal the junction or joint between the front and rear gondola part 3o and 28 and to prevent gas penetration from the bypass channel when the rear part of the pod 28 fully in the direction is shifted upstream, as can best be seen from Figure 2, then it surrounds the deflecting guide vanes 34 completely, so that the air flow through the Channel 24 flows out of the nozzle 26. When a reversal of the direction of the gas flow from the bypass channel is desired is, then the rear nacelle part 28 is fully displaced in the downstream direction, as can best be seen from FIG. The shift of the backward Gondola part 28 in the downstream direction causes the generally convex end face 38 of the rear Nacelle part, which protrudes into the bypass channel 24, hewn on the generally convex surface 4o of the engine ses 16 rests in the area 41 in such a way that the outflow nozzle 26 of the bypass channel is blocked and no bypass channel flow can be emitted through this nozzle. At the same time, the movement of the rear part of the pod 28 in the downstream direction exposes the surrounding areas.

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Steering guide vanes 34 causes and these are then in fluid connection with the bypass channel 24, so that the bypass channel flow or bypass flow flows out through the deflecting guide vanes 34 in the upstream direction and this creates a thrust in the reverse direction.

The convex surface 38 of the rear nacelle part 28 can be adjusted with respect to the convex surface 40 of the engine housing in such a way that the bypass channel 24 passes through an area of two cones in area 41 is sealed when the rear part of the nacelle is fully in the direction is shifted downstream. To improve the blocking of the bypass duct nozzle 26, a sealing ring 42 be provided on the circumference of the convex surface 38 of the rear nacelle part 28 or around the convex surface 40 of the engine housing 16.

The thrust reverser according to the invention can because of their simplicity can be easily set up for the thrust change in flight. For example, it may be desirable to have only a portion of the bypass channel flow through divert the guide vanes 34. This can be achieved by changing the position of the control arms 33 of the linear actuator as a function of the desired forward thrust. In this way, the rear part of the nacelle 28 can only be partially displaced downstream, in order to release a desired number of deflecting guide vanes and thereby that part of the bypass channel flow deflecting by the guide vanes 34, which is necessary to achieve a desired forward thrust. All known control systems for changing the angle of an inlet guide vane or the nozzle cross-section for the Thrust variations can be used for this purpose.

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A system of this type is shown, for example, in U.S. Patent No. 2,431,168.

It can be seen that the thrust reversing device described above is a single axially displaceable pod part used to reverse the bypass channel current and to accomplish the change in thrust, and is therefore significantly less complicated than previously known thrust reversing systems. The system according to the invention does not use any inflatable membranes which could fail if the membrane leaks. It doesn't use locking flaps either, which increase complexity, reduce maintainability and reliability, and furthermore that Increase the cost and weight of prior art thrust reversers. Furthermore, any losses that result from it the increased curvature of the bypass channel, which to rest between the shifted rearward Nacelle part 28 and the engine housing 16 is required, offset by the reduced weight, the reduced Gas passage and the reduced aerodynamic resistance of the thrust reverser according to the invention. Since neither the sliding rear gondola t1 nor are the cascade ring 34 attached to or connected to the engine housing 16 in any way, the assembly and disassembly of the thrust reverser on the engine is made easier and the load path used is precisely known. There is a counterforce for all forces on the actuators 31 and on the staggered guide vanes 34. The force curve is therefore without redundancy and therefore enables a more effective construction.

The foregoing was an embodiment of the present Invention described in connection with the figures

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Ak 27186Λ3

ben. However, the person skilled in the art will recognize that many modifications, substitutes and changes can be made to these shapes without departing from the broader scope of the basic concept of the invention. For example, it can be seen that the geometry of the fan duct 24 and the displacement of the rear nacelle part can be modified in order to achieve a desired flow rate through the passage 24 and at the same time maintain a blocking of the bypass passage 24 by a single axial displacement of the nacelle part 28. It can also be seen that the thrust reverser device according to the invention, because of its simplicity, offers a larger surface for acoustic treatment of the nacelle 12.

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Claims (9)

Claims 1.)) Thrust reverser system in a gas turbine of the type with a core engine enclosed by a casing is characterized in that it comprises: a nacelle enclosing the housing (16) at a distance (12) to form a bypass channel (24) between these two parts, wherein the gondola (12) has a fixed front part (3o) which is attached to a displaceable rear part Part (28) is applied, and the rear portion (28) has a generally curved surface (38) which protrudes into the bypass channel (24) and sealingly engages the housing (16) when the rear portion (28) is fully displaced downstream , a ring of staggered deflecting guide vanes (34) which are fixed in a fixed position with respect to the front nacelle part (3o) and displaceably with respect to the rear nacelle part (28), the deflecting guide vanes (34) being fully enclosed by the rear nacelle part (28) when the front and rear nacelle parts (3o, 28) lie against one another, and furthermore the guide vanes are in fluid connection with the bypass channel (24) when the front and rear nacelle parts (3o, 28) are separated from each other, Adjusting devices for the displacement of the rear nacelle part (28), whereby when the rear nacelle part (28) is fully displaced in the downstream direction, its radially extending surface (38) rests on the engine housing (16) to block the bypass channel flow between these parts, and at the same time the staf- 709846/1001 ORIGINAL INSPECTED Deflecting guide vanes (34) are exposed to reverse the outflow direction of the bypass duct flow. 2.) thrust reversing system according to claim 1, characterized in that it further comprises a thrust changing device for moving the Rückwärtsigen.Gondelteils (28) in positions between the fully shifted downstream Position and the position in which the rear and front cable parts (28, 3o) rest against one another, so that the forward thrust of the engine is achieved by selective diversion of part of the bypass duct flow can be changed by the staggered guide vanes (34). 3.) thrust reverser system according to claim 1, characterized in that the staggered guide vanes (34) are rigid are attached to the front nacelle part (3o). 4.) thrust reverser system according to claim 1, characterized in that there is still a seal (36) between the The front and rear gondola parts (3o, 28) are designed to change the passage of the bypass channel flow between the adjacent parts of the gondola. 5.) thrust reverser system according to claim 1, characterized in that that there is also a ring seal to prevent gas from passing through the bypass channel flow between the rear nacelle part (28) and the engine housing (16) when these two Parts lie next to each other. 6.) thrust reverser system according to claim 5, characterized in that the ring seal around the generally curved 9-845 / 1001 Surface (38) of the rear nacelle part (28) is attached. 7.) thrust reverser system according to claim 5, characterized in that the ring seal around the outer edge of the engine housing (1b) is attached. 8.) thrust reverser system according to claim 1, characterized in that there is another inside and outside of the nacelle (12) contains attached sound absorbing cladding (35). 9.) thrust reverser system according to claim 1, characterized in that the generally curved surface (38) of the rear nacelle part (28) is arranged so that it is in an area of two cones on the engine housing (16) is applied. 709845/1001