WO2016113104A1

WO2016113104A1 - Variable core-engine cowling for turbofan engines having a high bypass flow ratio

Info

Publication number: WO2016113104A1
Application number: PCT/EP2015/081326
Authority: WO
Inventors: Chetan Kumar SAIN; Marcel MISCHKE; Klaus HÖSCHLER
Original assignee: Brandenburgische Technische Universität Cottbus-Senftenberg
Priority date: 2015-01-15
Filing date: 2015-12-29
Publication date: 2016-07-21
Also published as: DE102015100602A1

Abstract

The invention relates to a core-engine cowling for turbofan engines having a high bypass flow ratio, comprising a plurality of movable segments (11, 12), which surround the core engine (7) in the outlet region of the bypass flow channel, wherein the segments (11) pointing toward the fan guide blade (3) and the segments (12) pointing toward the outlet region of the bypass flow channel form a plurality of overlapping regions (21, 22), wherein the overlapping regions are formed both in the circumferential direction of the core-engine cowling and in the axial direction thereto. Said invention uses the empty installation space (17) between the inner nozzle contour of the bypass flow channel and the core engine (7) that exists in the case of turbofan aircraft engines having a large bypass flow ratio. The invention thus provides a device that causes the inner contour of the bypass flow channel to be varied by means of overlapping sector profile elements of the nozzle.

Description

Variable core engine cowling for turbofan engines with high

By-pass ratio The work leading to this invention has been funded under the Grant Agreement No 604999 under the Seventh Framework Program of the [European Union] [European Atomic Energy Community] ([FP7 / 2007- 2013] [FP7 / 2007-201 1]) , The present invention relates to a variable core engine cowl for high bypass ratio turbofan engines.

Continuously increasing the by-pass ratio of commercial turbofan engines may require a variable bypass nozzle to operate the larger fan on a safer work line.

A high or high bypass ratio is when a multiple of the mass air flow carried by the core engine flows through the bypass duct. A high bypass ratio exists in particular when the air mass flow flowing through the bypass duct is about 15 to 20 times greater than the core engine flow. For example, the next generation of engines (civil aviation) will have a by-pass ratio of up to 20%.

Large turbofan engines have a very large fan diameter, which results in high peripheral speed at the fan blade tips. So that the blade tips do not run in the supersonic range and thus too large losses are generated, the fan must be operated at low speed. As a result, however, a lower pressure in the bypass channel is generated.

When starting the aircraft, the engine and thus the fan runs at maximum speed to produce the required starting thrust. Due to the strong rise in pressure in the bypass duct, it may happen that the required surge margin of the fan work line is undershot. The problem has not yet been solved satisfactorily. In the

US 2008/01 12802 A1 proposes a baffle arrangement which is arranged around the core engine. This consists of a displaceable in the axial direction component of one or more segments, which are not overlapping in the circumferential direction. The component is rotationally symmetrical and does not change the size of its surface during the movement in the axial direction, can thus be understood as a ring of one or more segments.

In US 3,237,864 A possibilities for changing the cross section of the flow channel are described, wherein the interaction of different segments takes place such that auxiliary components are used. In DE 10 201 1 106 959 A1 elastically formed adjusting elements are described, which configure the cross section of the flow channel changeable.

Furthermore, WO 2008/045067 A1 describes a translationally movable inner hood with aerodynamic flap sections.

Another attempt to solve the problem is in an axially displaceable section of the outer, rear nacelle of the Pratt & Whitney PW1000G turbofan engine. However, this solution has not yet been adopted for mass production. For this, the engine must have a long nacelle, which in turn brings a high weight and possible interference with the wing and fuselage or airframe with it. Due to the high weight and larger resistance area, more and / or stronger actuators are needed to allow the displacement. Furthermore, the change in the exit area is limited in this solution, since it depends strongly on the rigid inner contour of the bypass channel.

At present there is no application of variable nozzles for civil turbofan engines, which refers to the change of the inner nozzle contour. The object of the present invention is therefore to overcome the disadvantages of the prior art and to provide a simple and robust device to vary the contour of the bypass channel. The object is achieved by a core engine cowling, which has the features of the main claim. Advantageous embodiments are characterized in the dependent subclaims.

The object is further achieved by a method for changing the nozzle cross-section in turbofan engines with high bypass ratio, which has the features of the independent method claim.

The present invention is a core engine cowling for turbofan engines with high bypass ratio comprising a plurality of movable segments 1 1, 12, which surround the core engine 7 in the outlet region of the bypass channel, wherein the fan guide blade 3 facing segments 1 1 and the outlet of the Side flow channels facing segments 12 form a plurality of overlap areas 21, 22, wherein the overlapping areas are formed both in the circumferential direction of the core engine cowling and in the axial direction thereto.

According to the invention, it is preferred that the individual movable segments 1 1, 12 are each designed to be movable relative to one another such that the

Scope of the core lining is variable.

It is further particularly preferred that the individual movable segments 1 1, 12 are articulated on the sides of the segments 1 1, 12 remote from the overlapping areas 21, 22 in such a way by means of rotation axes 9, 10 that the

Segments 1 1, 12 are movable away from the core engine 7 or towards this.

According to the invention, it is also preferable for the individual movable segments 1 1, 12 to be elements on the surface facing the core engine 7 are arranged for moving the segments, wherein these elements are components of an actuator system for moving the segments 1 1, 12.

It is particularly preferred according to the invention that elements for moving the segments 1 1, 12 are formed as coupling rods 13, which are articulated by means of rotary joints 19, 20 to the segments 1 1, 12.

Furthermore, it is particularly preferred according to the invention that the actuator system of coupling rods 13, drive modules 14, rails 15 and fixtures 16 is formed.

Furthermore, it is particularly preferred according to the invention that the actuator system furthermore has at least one measuring, control and regulating unit (MSR unit) (50).

According to the invention it is further preferred that a plurality of actuator systems are provided which actuate in each case one or more or a plurality of segments 1 1, 12.

The subject of the present invention is also a method for changing the nozzle cross-section of the bypass duct in turbofan engines with high bypass ratio, wherein first detects the operating condition of the engine and optionally adapts the nozzle cross-section of the secondary flow channel, in which the circumference of the core panel, which Core engine 7 wrapped in the outlet of the bypass channel and which is formed of a plurality of movable segments 1 1, 12, changed by raising or lowering, in response to the detected operating state of the engine.

The invention thus provides an apparatus which effects the variation of the inner contour of the bypass duct by overlapping sector profiles of the nozzle. These profiles move radially inwards or outwards. As a result of the radial movement, the inner circumference of the bypass duct changes, as a result of which the effective outlet cross section of the bypass nozzle increases or decreases. The profiles glide nander to allow a gap-free contour as possible in the axial main flow direction. The drive takes place via an actuator system which pulls the individual segments of the variable bypass channel radially downward or pushes up, so as to vary the inner nozzle structure.

The purpose of the invention is to vary the nozzle exit surface of the bypass duct of a turbofan engine with a very high bypass ratio. Problem solving via a variable internal nozzle structure completely decouples the system from the turbofan engine nacelle. Thus, the nacelle can be optimally designed to reduce weight and minimize wing and cell interference. In addition, a very large area change can be achieved by varying the inner contour of the bypass channel. The inner surface is constructed from sector profiles to achieve a smooth and aerodynamically favorable structure of the secondary flow channel. Here, the smooth and aerodynamically favorable contours of the bypass channel are maintained. In addition, flow losses are minimized by the superposition of two adjacent sector profiles in the flow direction. With the aid of the variable nozzle cross-sectional area, the pressure in the bypass channel can be optimally adjusted for each operating point in order to guarantee a sufficient surge margin for the fan.

The following description explains the invention in more detail, without limiting the scope of the invention.

The present invention will be explained in more detail with the accompanying drawings. 1 shows, on the basis of a longitudinal section through a nacelle, the operating principle of the present invention with the variable inner nozzle structure of the bypass duct of turbofan aircraft engines;

FIG. 2 shows a view from the nacelle onto the variable segments and their overlapping areas; FIG. 3 shows a plan view according to FIG. 2 with an embodiment of an actuator system for the movement of the variable segments;

FIG. 3a is an enlarged view of a portion marked in FIG. 3; FIG.

4a shows the movement position of the variable segments in the extended state;

4b the movement position of the variable segments in the contracted state;

5a is an enlarged view of a portion of Figure 4a with the variable segments in the exploded state. and Fig. 5b is an enlarged view of a portion of Fig. 4b with the variable segments in the contracted state.

The application of the device according to the invention takes place in turbofan engines with a very high bypass ratio for safe and efficient operation of the fan. The operating points of the fan can be adjusted on his working line under different load ranges of the engine. The pressure of the air mass flow 5 conveyed through the fan 2 in the bypass duct is regulated by adjusting the nozzle cross-section 8 (exit surface) (FIG. 1). In addition, in the figure 1, the outer nacelle 1, the fan vane 3 behind the fan, the inlet 4 for the

Core stream, the core mass flow 6 and the nozzle section 18 of the exit of the core flow channel shown. Furthermore, the actuator system, which is formed from coupling rods 13, drive modules 14, rails 15 and fixtures 16, is shown. This actuator system moves the individual variable segments 1 1, 12 to set the desired contour. The function of the actuator system s is effected by an MSR unit 50. The measuring and control unit 50 comprises a corresponding sensor system as well as control and actuator controls. The MSR control unit 50 is integrated into the overall engine control in a known manner. The number of actuator system e used is determined by the number of variable segments. So it can be provided, in each case a pair of Segments 1 1, 12 to control by an actuator system. However, individual segments or a plurality or a plurality of individual segments or pairs of segments can also be controlled by a common actuator system. The number of segments and their geometric configuration naturally depends on the size of the core engine to be enclosed. Corresponding technical embodiments are the

Specialist familiar.

The basic principle of this invention is to change the nozzle cross-sectional area by moving the inner nozzle structure 11, 12 of the secondary flow channel by folding them together (opening the nozzle) and moving them apart (rotation) by rotation about their own axes of rotation 9, 10 the nozzle). The inner surface of the bypass channel is replaced by the front nozzle segments 1 1 and rear nozzle segments 12. The movement of the segments 1 1, 12 results in an overlap region in the circumferential direction 22 and in the axial direction 21 (Figure 2). This movement is realized, for example, by the following drive variants.

An embodiment of the present invention provides for axial movement on rails 15. The variable segments 1 1, 12 of the inner

Nozzle structure are connected by coupling rods 13 with drive modules 14. The coupling rods 13 are fixed to the respective rotary joints 19, 20 with the nozzle structures (Figure 3). The drive modules 14 run axially on rails 15 which are mounted on a holding device 16. The holding device 16 is fixedly mounted, for example, with the core engine. If the drive modules 14 move relative to one another, the nozzle segments 1 1, 12 are pulled together with the aid of the coupling rods 13 and thus the nozzle cross-section of the bypass channel 8 is increased. Similarly, the nozzle cross-section of the bypass duct 8 is reduced when the drive modules 14 are pulled apart.

This invention uses the empty space 17 between the inner nozzle contour of the bypass duct and the core engine 7, which is present in turbofan aircraft engines with a large bypass ratio. The contours of the segments 11, 12 are designed to slide on the adjacent segments and thus overlap each other 21 (Figure 2). The overlap region 22 is in the flow direction and thus no large losses are generated by steps or gaps. The same applies to the overlap 21 of the front 1 1 and rear segments 12 in the circumferential direction. The rear segments 12 are moved below the front segments 1 1, so that a smooth flow contour is formed in the bypass channel. Figures 4a and 4b show the movement positions of the nozzle segments 1 1, 12. Figures 5a and 5b illustrate the overlapping regions 22 of the nozzle segments in the circumferential direction. In addition, the movement of the segments during the overlap in the radial direction through the region 23 is shown.

LIST OF REFERENCE NUMBERS

1 gondola

2 fans

3 fan guide vane

4 core current inlet

5 secondary flow in the bypass duct

6 core mass flow

7 core engine

8 nozzle cross-section bypass channel

9 axis of rotation

10 axis of rotation

1 1 front nozzle segments

12 rear nozzle segments

13 coupling rod

14 drive module

15 tracks

16 holding device

17 empty space

18 nozzle cross section core flow channel

19 rotary joint

20 rotary joint

21 Overlap area in the axial direction

22 Overlap area in the circumferential direction

23 overlap area in the radial direction

50 MSR unit

Claims

claims

1 . Core engine cowl for high bypass turbofan engines, comprising a plurality of movable segments (11, 12) enveloping the core engine (7) in the outlet region of the bypass duct, the segments (11) facing the fan blade (3) ) and the segments (12) facing the outlet area of the bypass duct form a plurality of overlapping areas (21, 22), the overlapping areas being formed both in the circumferential direction of the core engine cowling and in the axial direction thereto.

2. core engine cowling, according to claim 1, characterized in that the individual movable segments (1 1, 12) are each designed to be movable relative to each other, that the circumference of the core lining is variable.

3. core engine cowling, according to claim 1 or 2, characterized in that the individual movable segments (1 1, 12) on the overlapping areas (21, 22) facing away from the sides of the segments (1 1, 12) by means of axes of rotation (9, 10 ) are hinged, that the segments (1 1, 12) from the core engine (7) away or towards this are movable.

4. core engine cowling, according to at least one of the preceding claims, characterized in that the individual movable segments (1 1, 12) on the core engine (7) facing surface elements are arranged to move the segments, said elements being components of an actuator system for moving the segments (1 1, 12).

5. core engine cowling, according to claim 4, characterized in that elements for moving the segments (1 1, 12) as coupling rods (13) are formed, which are articulated by means of rotary joints (19, 20) on the segments (1 1, 12) ,

6. core engine cowling, according to claim 4 or 5, characterized in that the actuator system of coupling rods (13), drive modules (14), rails (15) and holding devices (16) is formed.

7. core engine cowling, according to at least one of claims 4 to 6, characterized in that the actuator system further comprises at least one MSR unit (50).

8. core engine cowling, according to at least one of claims 4 to 7, characterized in that a plurality of actuator system e are provided, each of which actuate one or more or a plurality of segments (1 1, 12).

9. A method for changing the nozzle cross section of the Nebenstromka- channel (8) in turbofan engines with high bypass ratio, wherein first detects the operating condition of the engine and optionally the nozzle cross-section of the bypass channel (8) adapts, in which the circumference of the core lining, which the core engine (7) is enveloped in the outlet region of the bypass duct (5) and is formed by a plurality of movable segments (1 1, 12), by raising or lowering, in response to the detected operating condition of the engine.