DE102019129998B4 - Aircraft with jet engines above the wings and with a local extension of the fuselage to reduce aerodynamic drag at transonic flight speeds - Google Patents

Abstract

Aircraft (1) with- a fuselage (2) extending along a central axis (3),- a pair of hydrofoils (6) which connect laterally to the fuselage (2) in wing connection areas (7) below the central axis (3), and- a pair of jet engines (9) mounted on pylons (10) at a vertical distance (29) above the wings (6) and at a horizontal distance (30) to the fuselage (2),- the jet engines (9) and the pylons (10) along the central axis (3) do not begin in front of a center of the wing connection areas (7), - with a basic shape of the fuselage (2), the round or rounded basic cross sections (26) perpendicular to the central axis ( 3), extending along the central axis (3) continuously over the wing connection areas (7), the jet engines (9) and the pylons (10), characterized in that the fuselage (2) above the central axis (3) has a local widening (13) has its basic shape - along the central axis (3) in a first Distance (20) in front of a foremost point of the jet engines (9) and the pylons (10) begins and ends at a second distance (21) behind a rearmost point of the jet engines (9) and the pylons (10) and- the basic cross-sections ( 26) of the basic shape above the central axis (3) by cross-sectional expansion areas (25),- the cross-sectional expansion areas (25) along the central axis (3) initially increasing from zero, then decreasing again in the area of the jet engines (9) and the pylons (10) to reach a local extension area minimum (27), and then increase again to finally decrease to zero.

Description

TECHNICAL FIELD OF THE INVENTION

The invention relates to an aircraft with a fuselage extending along a central axis, with a pair of wings, which connect laterally to the fuselage in wing confinement areas below the central axis, and with a pair of jet engines, which are vertically spaced above the wings and are mounted on pylons at a horizontal distance from the hull. The jet engines and the pylons do not start before a center of the wing connection areas along the central axis. A basic shape of the fuselage, which has round or rounded basic cross-sections perpendicular to the central axis, extends continuously along the central axis over the wing connection areas, the jet engines and pylons.

In particular, the aircraft is an airliner.

STATE OF THE ART

Many current commercial aircraft have two jet engines located below their wings. Jet engine efficiency can be improved by increasing the bypass ratio. The by-pass ratio describes the ratio between the air mass flow which, downstream of the engine fan, is guided past the gas turbine of the respective jet engine, i. H. the bypass flow, and the air mass flow, which passes the gas turbine of the respective jet engine, d. H. the core flow. In the jet engines of some current aircraft, the bypass ratio is already 10:1 or even higher. Increasing the bypass ratio results in an increase in engine diameter. Below the wings, there are geometric limits to this increase, for example due to the necessary length of the landing gear.

If jet engines are used in an aircraft with a cruising speed in the high subsonic range, i. H. a so-called transonic cruising speed, above which the wings are arranged, it should be noted that local supersonic areas of the air flow occurring there can cause negative effects such as strong compression shocks up to shock-induced flow separations. These effects have significant increasing effects on the aerodynamic drag and hence the fuel consumption of the aircraft at its cruising speed.

From the DE 932 410 B a low-drag design of high-speed aircraft, including those with displacement bodies lying outside the aircraft outline, is known. Parts around which the airstream flows, including any displacement bodies arranged outside the aircraft outline, are arranged in their shape and position in relation to one another in such a way that the sum of their displacement cross-sections in common planes lying one behind the other transversely to the direction of flight, viewed from the beginning to the end of the aircraft, until a maximum value is reached only increases and only decreases from the maximum value to zero at the end of the aircraft. The increase and decrease does not occur abruptly in order to avoid the critical Mach number being exceeded prematurely.

From the WO 20041 043 780 A2 is an aircraft with a fuselage extending along a central axis, with a pair of hydrofoils, which are laterally connected to the fuselage in wing connection areas below the central axis, and with a pair of jet engines. The jet engines are mounted at a vertical distance above the wings and at a horizontal distance from the fuselage on pylons extending horizontally from the fuselage to the jet engines. The jet engines and pylons overlap a rear portion of the trapezoidal airfoil. Rounded basic cross-sectional areas of a basic shape of the fuselage initially increase until just in front of the wings. The base cross-sectional areas then decrease to a local minimum base cross-sectional area in a central region of the pylons and jet engines coinciding with the aft end of the wings. The basic cross-sectional areas then increase slightly again until, after a local maximum of the basic cross-sectional area behind the jet engines, they drop towards zero towards the end of the fuselage. The fuselage therefore has a waist in the area of the wings, the jet engines and the pylons, so that the total cross-sectional areas of the aircraft steadily increase up to a total cross-sectional area maximum and then steadily decrease again to zero.

OBJECT OF THE INVENTION

The invention is based on the object, in an aircraft flying at transonic flight speeds with jet engines arranged above the wings, to avoid strong compression shocks through to shock-induced flow separations in the area of the jet engines and in the duct between the fuselage and the jet engine, in order, in particular in a commercial aircraft with transonic cruising speed to reduce the aerodynamic resistance and the associated fuel consumption.

SOLUTION

The object is achieved according to the invention by an aircraft having the features of independent patent claim 1 . Preferred embodiments of the aircraft according to the invention are defined in the dependent claims.

DESCRIPTION OF THE INVENTION

An aircraft according to the invention has a fuselage extending along a central axis, a pair of wings that connect laterally to the fuselage in wing connection areas below the central axis, and a pair of jet engines that are vertically spaced above the wings and horizontally spaced from are mounted on pylons on the fuselage. The jet engines and the pylons do not start before a center of the wing connection areas along the central axis. A basic shape of the fuselage, which has round or rounded basic cross sections perpendicular to the central axis, extends continuously along the central axis over the wing connection areas, the jet engines and the pylons. Above the central axis, the fuselage shows a local extension of its basic form. The local extension begins along the central axis at a first distance forward of a foremost point of the jet engines and the pylons; and it terminates a second distance aft of an aft point of the jet engines and pylons. The local expansion expands the basic cross-sections of the basic form above the central axis by cross-section expansion areas. In the process, the cross-sectional expansion areas along the central axis initially increase from zero. Then the cross-sectional expansion areas decrease again in order to reach a local expansion area minimum in the area of the jet engines and the pylons. Subsequent to the local expansion area minimum, the cross-sectional expansion areas increase again and finally decrease to zero.

The local expansion of the basic shape of the fuselage can be realized by corresponding local bulges in the fuselage itself or by a displacement body placed on the fuselage. In any case, the cross-sectional expansion areas, which are already increasing in front of the pylons and the jet engines, allow the local expansion of the basic shape of the fuselage to reduce the cross-sectional expansion areas in the area of the jet engines again. As a result, the geometric constriction caused by the jet engines and thus the acceleration of the air flow is reduced in the course of the flow and essentially limited to a change in direction. Strong compression shocks and the associated flow separations are thus avoided.

In the aircraft according to the invention, the cross-sectional expansion areas along the central axis both decrease and increase continuously. Preferably, the course of the change in the cross-sectional expansion areas along the central axis, i. H. the derivation of the cross-sectional expansion areas continuously. The local extension of the fuselage thus has a smooth contour without aerodynamically unfavorable jumps and edges.

In the aircraft according to the invention, the basic cross-sections of the basic shape of the fuselage can remain the same over the wings, the jet engines and the pylons and/or over the local expansion of the fuselage and beyond. The cross-sectional areas of the fuselage then only vary due to the local expansion of the fuselage. In particular, the fuselage of the aircraft according to the invention does not have any waisting or any other local reduction in its cross-sectional areas.

In the aircraft according to the invention, the cross-sectional expansion areas preferably do not project upwards beyond the respective basic cross-section of the fuselage. Such a projection of the cross-sectional expansion surfaces over the respective basic cross-section of the fuselage is also preferably not given laterally. In other words, the height and width of the hull are preferably not increased by its local expansion.

In the aircraft according to the invention, the jet engine inlets can be arranged along the central axis in the area of the trailing edges of the wings. The area of the trailing edges of the wings is to be understood as an area that begins up to 10% of an engine fan diameter of the jet engines along the central axis in front of the trailing edges of the wings and ends up to 3% of the engine fan diameter of the jet engines along the central axis behind the trailing edges of the wings. When the engine inlets are positioned in this area of the wing trailing edges, a flow channel is formed between the wing and the engine nacelles of the jet engines, the flow through which is positively influenced by the inventive local widening of the fuselage.

The first distance at which the local widening begins in the aircraft according to the invention in front of the foremost point of the jet engines and the pylons can in particular be between 75% and 125% of the engine fan diameter Jet engines amount to from the engine inlets of the jet engines. Along the central axis, the local expansion typically begins in the wing connection areas.

In the aircraft according to the invention, the largest of the cross-sectional expansion areas of the local expansion is typically between 4.5% and 8% of the squared engine fan diameter of the jet engines. That is about 6% to 10% of the area of the engine fan, which is a measure of the total air mass flow through the respective jet engine.

In the aircraft according to the invention, the largest of the cross-sectional extension areas along the central axis can be in front of the local extension area minimum. More specifically, the largest of the cross-sectional areas of extension may be located a third distance along the central axis between 40% and 60% of the engine fan diameter of the jet engines forward of the jet engine inlets of the jet engines.

The local flare area minimum may be located along the central axis at a fourth distance between 100% and 170% of the engine fan diameter of the jet engines aft of the jet engine inlets. It is then typically still in the range of jet engines, i. H. in front of the jet engine trailing edges of the jet engines.

The local extension area minimum can be between 0% and 1% or between 0% and 0.25% of the engine fan diameter squared of the jet engines. One percent of the squared engine fan diameter corresponds to about 1.27% of the area spanned by the engine fan.

The second distance at which the local extension along the centerline ends aft of the rearmost point of the jet engines and pylons may be between 150% and 200% of the engine fan diameter of the jet engines from the jet engine trailing edges. This measure for the end of the local widening can also be related to the trailing edges of the jet engine if the pylons only end behind the trailing edges of the jet engine.

In the aircraft according to the invention, the wings can end downwards at horizontal tangents to the basic cross-sections of the basic shape of the fuselage. The wing connection areas are thus arranged as low as possible on the fuselage.

The pylons on which the jet engines are mounted can connect to the side of the fuselage and thus laterally limit the flow channel above the wings beyond the engine nacelles of the jet engines. In principle, however, the pylons can also extend from the wings to the jet engines.

If the pylons are attached laterally to the fuselage of the aircraft according to the invention, the pylons can end upwards at horizontal tangents to the basic cross-sections of the basic shape of the fuselage and thus be attached to the fuselage as high as possible.

The local extension of the fuselage of the aircraft according to the invention can provide additional space within the fuselage. This space can be integral with the rest of the space in the hull or separate from it. In the latter case, too, electrical and/or electronic devices of the aircraft, specifically antennas for example, can be arranged in the local extension of the fuselage.

As already indicated, the aircraft according to the invention is designed in particular for a cruising speed in the transonic range.

Advantageous developments of the invention result from the patent claims, the description and the drawings.

The advantages of features and combinations of several features mentioned in the description are merely exemplary and can have an effect alternatively or cumulatively without the advantages necessarily having to be achieved by embodiments according to the invention.

The following applies to the disclosure content - not the scope of protection - of the original application documents and the patent: Further features can be found in the drawings - in particular the illustrated geometries and the relative dimensions of several components to one another as well as their relative arrangement and operative connection. The combination of features of different embodiments of the invention or of features of different patent claims is also possible, deviating from the selected dependencies of the patent claims and is hereby suggested. This also applies to those features that are shown in separate drawings or are mentioned in their description. These features can also be combined with features of different patent claims. Also listed in the claims Merk This does not apply to the independent patent claims of the granted patent.

The features mentioned in the patent claims and the description are to be understood with regard to their number in such a way that exactly this number or a larger number than the number mentioned is present, without the need for an explicit use of the adverb “at least”. If, for example, a displacement body is mentioned, this is to be understood in such a way that exactly one displacement body, two displacement bodies or more displacement bodies are present. The features listed in the patent claims can be supplemented by further features or can be the only features that the respective aircraft has.

The reference signs contained in the claims do not limit the scope of the subject-matter protected by the claims. They only serve the purpose of making the claims easier to understand.

character list

• 1 ist eine perspektivische Ansicht eines erfindungsgemäßen Flugzeugs schräg von vorne oben.
• 2 ist eine Ansicht des erfindungsgemäßen Flugzeugs gemäß 2 von vorne.
• 3 ist eine Ansicht von oben auf eine Hälfte des erfindungsgemäßen Flugzeugs gemäß 1 und 2.
• 4 ist ein in 3 mit einem Kreis markiertes Detail in vergrößerter Darstellung.
• 5 ist ein Schnitt längs einer Schnittlinie B-B in 4.
• 6 ist ein Schnitt entlang einer Schnittlinie C-C in 4.
• 7 ist eine Auftragung von Querschnittsflächen von Bestandteilen der Hälfte des erfindungsgemäßen Flugzeugs gemäß 3 über seiner Längserstreckung.

The invention is further explained and described below with reference to preferred exemplary embodiments illustrated in the figures.

• 1 Figure 12 is a front and top perspective view of an aircraft according to the invention.
• 2 12 is a view of the aircraft according to the invention in FIG 2 from the front.
• 3 12 is a top view of one half of the aircraft according to the invention in FIG 1 and 2 .
• 4 is a in 3 Enlarged detail marked with a circle.
• 5 is a section along section line BB in 4 .
• 6 is a section along a section line CC in 4 .
• 7 Figure 12 is a plot of cross-sectional areas of components of half of the aircraft according to the invention 3 over its length.

FIGURE DESCRIPTION

That in the 1 and 2 The aircraft 1 shown has a fuselage 2 which extends along a central axis 3 . The fuselage 2 has a basic shape with approximately circular cross sections perpendicular to the central axis 3 . In a main area behind a nose 4 and in front of a tail 5 of the fuselage 2, the basic cross sections of the basic shape of the fuselage 2 remain the same. In this main area, two hydrofoils 6 are attached to the fuselage 2 in wing connection areas 7 . The wing connection areas 7 are provided with fairings 8, a so-called belly, which can also cover a retracted landing gear of the aircraft 1. Jet engines 9 of the aircraft 1 are arranged above the wings 6 and are offset to the rear along the central axis 3 in relation to the wings 6 . The jet engines 9 are mounted on pylons 10 at vertical distances 29 from the wings 6 and at horizontal distances 30 from the fuselage 2 , which are aligned horizontally below and along an upper tangent to the fuselage 3 . Flow channels 12 are formed between the engine nacelles 11 of the jet engines 9 and the pylons 10 on the one hand and the wings 9 on the other. At flight speeds of the aircraft 1 in the transonic range, limited supersonic flow areas can occur in the flow ducts 12 and strong compression shocks can then occur, which significantly increase the aerodynamic resistance of the aircraft 1 . In order to prevent such strong compression shocks, the basic shape of the fuselage 2 is provided above the central axis 3 with a local widening 13, which begins along the central axis 3 in the wing connection areas 7, ends behind the jet engines 9 and pylons 10 and in the area of the flow channels a waist having. An elevator and rudder 14 of the aircraft 1 is arranged at a distance from the local extension at the tail 5 of the aircraft 1 .

3 and the inside 3 marked with a circle and in 4 The detail shown on an enlarged scale shows the exact position of one of the engines 9 in relation to the associated wing 6. An engine inlet 15 of the jet engine 9 falls in an area of a wing trailing edge 16 of the wing 6. The pylon 10 supporting the jet engine 9 extends along the central axis 3 to behind an engine trailing edge 17 of the jet engine 9. The local extension 13 of the fuselage 2 begins in front of the engine inlet 15 and thus also in front of the pylon 10 and ends behind the engine trailing edge 17 and the pylon 10. The local extension 13 runs both forwards and backwards along the central axis 3. In between, their cross-sectional areas decrease temporarily in the area of the pylon 10 to a local area minimum at a position 18 . The local widening begins at a first distance 20 in front of the engine inlet 15 , this first distance 20 being between 75% and 125% of an engine fan diameter 19 of an engine fan 28 of the engine 9 . The local extension 13 ends at a second distance 21 behind the shoot factory trailing edge 17, this second distance 21 being between 150% and 200% of the engine fan diameter 19. A largest of the cross-sectional extension areas of the local extension 13 is at a position 22 at a third distance 23 in front of the engine inlet 15. This third distance 23 is between 40% and 60% of the engine fan diameter 19. The position 18 of the local extension area minimum of the local extension 13 is longitudinal the central axis 3 at a fourth distance 24. This fourth distance 24 is between 100% and 170% of the engine fan diameter 19.

5 shows the largest cross-sectional extension area 25 of the local extension 13 at the position 22 in 4 , which expands the basic cross section 26 of the basic shape of the hull 2 in its main area above the central axis 3 without increasing a maximum height or width of the basic cross section 26 . The largest cross-sectional expansion area 25 is between 6 and 10% of the area swept by the engine fan 28 with the engine fan diameter 19 .

6 shows the local extension area minimum 27 at position 18 in 4 , which does not significantly increase the total cross-sectional area beyond the pylon 10. The local expansion area minimum 27 typically remains less than 0.3% of the area swept by the engine fan 28 with the engine fan diameter 19 .

In 7 are the cross-sectional areas of the components of half of the aircraft according to the invention 3 in square meters plotted against the x-position along the central axis 3 in meters. The cross-sectional areas are added up starting with that of the fuselage 2 . The cross-sectional areas of the fuselage 2 are followed by those of the fairing 8, the wing 6 including the wing connection area 7, the jet engine 9, the local extension 13 and the pylon 10. Despite the significant effect on the flow through the flow channels 12 according to 2 the local expansion 13 changes the course of the sum of the cross-sectional areas only slightly, and in no way does the course of the total cross-sectional areas of a so-called Sears-Haak body, i.e. an ogive optimized for supersonic flight, as shown in 7 shown with a dashed line for comparison. Essentially, the local extension 13 shortens the collapse of the total cross-sectional areas at the trailing edge of the wing 13 in front of the jet engine 9. Furthermore, the local extension 13 intercepts part of the increase and the subsequent reduction in the total cross-sectional areas through the pylon 10.

Reference List

1

Airplane

2

hull

3

central axis

4

Nose

5

Rear

6

airfoil

7

wing connection area

8th

disguise

9

Jet engine

10

pylon

11

engine nacelle

12

flow channel

13

local extension of the trunk 2

14

Elevator and rudder

15

engine intake

16

wing trailing edge

17

engine trailing edge

18

Location of local extension area minimum 27

19

engine fan diameter

20

first distance

21

second distance

22

Position of the largest cross-sectional expansion area 25

23

third distance

24

fourth distance

25

largest cross-sectional expansion area

26

basic cross section

27

local extension area minimum

28

engine fan

29

vertical distance

30

horizontal distance

Claims (17)

Aircraft (1) with - a fuselage (2) extending along a central axis (3), - a pair of hydrofoils (6) which connect laterally to the fuselage (2) in wing connection areas (7) below the central axis (3), and - a pair of jet engines (9) mounted at a vertical distance (29) above the wings (6) and at a horizontal distance (30) to the Fuselage (2) are mounted on pylons (10), - wherein the jet engines (9) and the pylons (10) along the central axis (3) do not begin before a center of the wing connection areas (7), - wherein a basic shape of the fuselage ( 2) which has round or rounded basic cross-sections (26) perpendicular to the central axis (3), along the central axis (3) continuously over the wing connection areas (7), the jet engines (9) and the pylons (10), characterized that the fuselage (2) has a local extension (13) of its basic shape above the central axis (3), - along the central axis (3) at a first distance (20) in front of a foremost point of the jet engines (9) and the pylons (10) and ends at a second distance (21) behind a rearmost point of the jet engines (9) and the pylons (10) and - which expands the basic cross-sections (26) of the basic shape above the central axis (3) by cross-sectional expansion areas (25). , - where the cross-section sion surfaces (25) along the central axis (3) initially increase from zero, then decrease again in order to reach a local expansion surface minimum (27) in the area of the jet engines (9) and the pylons (10), and then increase again to finally to take zero. Airplane (1) to claim 1 , characterized in that the cross-sectional expansion areas (25) continuously increase and decrease. Aircraft (1) according to one of the preceding claims, characterized in that the basic cross sections (26) of the basic shape over the wings (6), the jet engines (9) and the pylons (10) and/or over the local extension (13) of the fuselage (2) remain the same. Aircraft (1) according to one of the preceding claims, characterized in that the cross-sectional expansion areas (25) do not protrude upwards beyond the respective basic cross-section (26). Aircraft (1) according to one of the preceding claims, characterized in that the cross-sectional expansion areas (25) do not protrude laterally beyond the respective basic cross-section (26). Aircraft (1) according to one of the preceding claims, characterized in that the jet engine inlets (15) are arranged along the central axis (3) in the region of the trailing edges of the wings (6). Aircraft (1) according to one of the preceding claims, characterized in that the local widening (13) along the central axis (3) in the first distance (20) is between 75% and 125% of the engine fan diameter (19) of the jet engines (9). the jet engine inlets (15) of the jet engines (9) begins. Aircraft (1) according to one of the preceding claims, characterized in that the largest of the cross-sectional expansion areas (25) is between 4.5% and 8% of the squared engine fan diameter (19) of the jet engines (9). Aircraft (1) according to one of the preceding claims, characterized in that the largest of the cross-sectional expansion areas (25) along the central axis (3) at a third distance (23) between 40% and 60% of the engine fan diameter (19) of the jet engines (9) is arranged in front of the jet engine inlets (15) of the jet engines (9). Aircraft (1) according to one of the preceding claims, characterized in that the local expansion area minimum (27) along the central axis (3) at a fourth distance (24) between 100% and 170% of the engine fan diameter (19) of the jet engines (9) behind the jet engine inlets (15) is arranged. Aircraft (1) according to one of the preceding claims, characterized in that the local expansion area minimum (27) is between 0% and 1% or between 0% and 0.25% of the squared engine fan diameter (19) of the jet engines (9). Aircraft (1) according to one of the preceding claims, characterized in that the local extension (13) along the central axis (3) in the second distance (21) between 150% and 200% of the engine fan diameter (19) of the jet engines (9) behind the jet engine trailing edges of the jet engines (9) ends. Aircraft (1) according to one of the preceding claims, characterized in that the wings (6) end downwards at horizontal tangents to the basic cross-sections (26). Airplane (1) according to one of the preceding claims, characterized in that the pylons (10) are connected laterally to the fuselage (2). Airplane (1) to Claim 14 , characterized in that the pylons (10) upwards end at horizontal tangents to the basic cross-sections (26). Aircraft (1) according to one of the preceding claims, characterized in that electrical and/or electronic devices of the aircraft (1) are arranged in the local extension (13) of the fuselage (2). Aircraft (1) according to one of the preceding claims, characterized in that the aircraft (1) is designed for a cruising speed in the transonic range.

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