JP2002053099A - Aerodynamic characteristic improvement device for aircraft and aircraft equipped with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide such a device for improving an aerodynamic characteristic that a nonlinear aerodynamic characteristic caused by a peeling off of border layer is not generated. SOLUTION: In an airframe shape having a large contraction toward a rear side of the airframe, a border layer cannot bear a pressure recovery and is peeled off from an airframe surface. A position at which the airframe surfaces 2L, 2R are started to incline at a predetermined angle or more against a forward/backward axis CL of the airframe is made to a front end A and wedge- like projection 11L, 11R extending to the rear side of the airframe at an enlargement toward the edge are provided on the airframe surface. Thereby, since an air stream is locally accelerated and a peeling off of the border layer is inhibited, it can be prevented that the aerodynamic characteristic becomes nonlinear and a gentle flight characteristic in which a deflection is not generated at an airframe attitude can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for improving the aerodynamic characteristics of an aircraft, and more particularly, to an aerodynamic characteristic of an aircraft in which a boundary layer is separated at a portion of the body surface narrowed toward the rear of the aircraft. And a device for preventing the device from becoming non-linear.

[0002]

2. Description of the Related Art A jet engine employing a centrifugal compressor or a turbine has a large throttle at a nozzle portion. Therefore, as shown in FIG. Will be squeezed according to the engine shape.

At this time, the left and right side surfaces 2L, 2R of the body 2
If the inclination of the vehicle relative to the longitudinal axis of the vehicle exceeds a predetermined angle, boundary layer separations 3L and 3R may occur. Such boundary layer separations 3L and 3R not only cause an increase in drag, but also cause a change in the airflow direction when the aircraft slides, for example, rightward in the figure as shown by an arrow α in FIG. Since the boundary layer in the 2R becomes thinner, an aerodynamic force is generated to push the rear part of the fuselage rightward as shown by the arrow β in FIG. As a result, as shown in FIG. 15, the characteristic of the yawing moment with respect to the side slip angle of the aircraft becomes nonlinear, which is not preferable.

Similarly, if the elevation angle of the fuselage changes when boundary layer separation occurs on the upper and lower surfaces of the rear portion of the fuselage, an air force is generated to push the rear portion of the fuselage upward or downward. As described above, the characteristic of the pitching moment with respect to the elevation angle becomes nonlinear, which is not preferable.

Therefore, conventionally, separation of the boundary layer is prevented by loosening the narrowing of the rear part of the fuselage or attaching a vortex generator, so that non-linear aerodynamic characteristics are not generated.

Further, by increasing the area of a stabilizer such as a horizontal stabilizer, a vertical stabilizer or a ventral fin,
It compensates for the reduced stability due to the non-linear aerodynamics caused by the separation of the boundary layer.

[0007]

However, if the shape of the body is narrowed down to prevent airflow separation at the rear of the body, not only the outer shape and the internal structure of the body need to be changed significantly, but also the base area becomes small. Invites an increase.

Further, the vortex generator needs to be installed at a place where the boundary layer is not separated and at an appropriate height and angle with respect to the flow direction of the airflow. If the local airflow direction is not constant, installation is difficult.

Further, the increase in the area of the horizontal tail and the vertical tail and the addition of ventral fins not only cause the non-linear aerodynamic characteristics to remain slightly, but also change the equipment such as the body structure and the actuator.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to suppress changes in the outer shape and internal structure and equipment of the fuselage, and to reduce the nonlinear aerodynamic characteristics caused by boundary layer separation. It is an object of the present invention to provide a device for improving aerodynamic characteristics so as not to occur.

[0011]

According to a first aspect of the present invention, there is provided an aircraft aerodynamic characteristic improving device which protrudes from a portion of a body surface of an aircraft which is narrowed toward the rear of the body. And a wedge-shaped protrusion extending divergently toward the rear of the fuselage. At this time, the protruding portion protrudes from the body surface with a position on the body surface that starts to incline at a predetermined angle or more with respect to the body longitudinal axis as a front end thereof. In addition, the height of the protruding portion protruding from the body surface at the rear end is set to approximately half the thickness of the boundary layer formed on the body surface at the rear end position. The wedge-shaped protrusion is preferably hollow to reduce the weight of the body, but may be solid.

That is, in an airframe shape having a large throttle toward the rear of the airframe, the boundary layer may not be able to withstand the pressure recovery and may be separated from the airframe surface. However, when the aerodynamic characteristic improving device according to the present invention is attached to the airframe surface, Since the airflow is locally accelerated and separation of the boundary layer is suppressed, it is possible to prevent the aerodynamic characteristics from becoming non-linear. As a result, it is possible to improve the aerodynamic characteristics of the aircraft and realize straightforward flight characteristics in which the body attitude does not change. Further, the aerodynamic characteristic improving device according to the present invention can be mounted on the surface of the fuselage without significantly changing the outer shape and internal structure of the fuselage.

According to a fourth aspect of the present invention, there is provided an aircraft aerodynamic characteristic improving device for projecting a portion of a body surface of an aircraft which is narrowed toward the rear of the aircraft.
It has a plate-shaped protrusion extending vertically and horizontally with respect to the longitudinal axis of the fuselage. That is, when a flat plate-shaped protrusion is protruded from the body surface narrowed down toward the rear of the body, airflow stagnation occurs upstream of the plate-shaped protrusion, so that the same effect as the wedge-shaped protrusion described above can be obtained. .

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an aerodynamic characteristic improving apparatus for an aircraft according to the present invention will be described in detail with reference to FIGS. In the following description, the same portions as those of the above-described conventional technology are denoted by the same reference numerals, and description thereof will be omitted.

First Embodiment As shown in FIGS. 1 and 2, the fuselage 2 of the aircraft 10 according to the first embodiment has a left and right side surface 2L, which is closer to the rear end 2a.
The 2R is gradually narrowed toward the rear of the fuselage so that the interval in the width direction of the fuselage is reduced. As a result, there is a possibility that boundary layer separation may occur in a portion of the left and right side surfaces 2L and 2R of the fuselage 2 where the inclination angle with respect to the fuselage longitudinal axis CL exceeds a specific angle.

Therefore, a pair of left and right aerodynamic characteristic improvement devices 11L and 11R for preventing separation of the boundary layer are provided at the rear end portions of the left and right side surfaces 2L and 2R of the body 2 respectively.
As shown in FIGS. 1 to 3, these aerodynamic characteristic improving devices 11L and 11R are formed as wedge-shaped protrusions extending divergently toward the rear of the fuselage. This is indicated by reference numeral B.

A pair of left and right aerodynamic characteristic improvement devices 11L, 11
When the fuselage 2 is cut along a horizontal plane extending parallel to the fuselage longitudinal axis CL as shown in FIG. 4, the front end A of the R has a predetermined angle with respect to the left and right sides 2L and 2R of the fuselage 2 with respect to the fuselage longitudinal axis CL. This is a position where the inclination starts at an angle of θ or more. That is,
At the rear of the fuselage from the front end A, the right and left sides 2 of the fuselage 2
L, 2R incline at an angle equal to or greater than the predetermined angle θ with respect to the body longitudinal axis CL. Note that the predetermined angle θ is obtained by calculating conditions under which boundary layer separation is expected, based on preconditions such as the body dimensions of the aircraft 10, the flight altitude, and the flight speed.

A pair of left and right aerodynamic characteristic improvement devices 11L, 11
The rear end B of R is connected to these aerodynamic characteristic improvement devices 11L, 11L.
When the R is not installed, a point which is separated from the left and right side surfaces 2L, 2R by a dimension T which is a value of １ ／ of the thickness of the boundary layer generated on the left and right side surfaces 2L, 2R of the body 2 respectively. It can be obtained by obtaining on the same plane as the rear end 2a.

The above operation is performed on a plurality of horizontal planes extending parallel to the longitudinal axis CL of the aircraft, and the points A and B are determined for each horizontal plane, and the points A and B are connected by straight lines on each horizontal plane to form a pair of left and right sides. The side surface 11a of the aerodynamic characteristic improvement device 11L, 11R is determined. By smoothly connecting the plurality of points A and B obtained in this way, the leading edge and the trailing edge of the pair of left and right aerodynamic characteristic improvement devices 11L, 11R can be determined. That is, a pair of left and right aerodynamic characteristic improvement devices 11
The leading edge and the trailing edge B of L, 11R are the fuselage 2 of the aircraft 10.
Is determined according to the shape of. In addition, as a simple method, the intersection of the plane perpendicular to the longitudinal axis CL of the aircraft passing through the point A located at the foremost and the left and right side surfaces 2L and 2R of the fuselage 2 is improved by a pair of left and right aerodynamic characteristics. It may be the leading edge of the devices 11L and 11R.

A pair of left and right aerodynamic characteristic improvement devices 11L, 11
The vertical width of R is set so as to cover an area where boundary layer separation is expected, but this causes an increase in air resistance.
As shown in the above, it is preferable to set H1 which is about 1/3 of the vertical dimension H0 at the rear end 2a of the body 2.

When the shape of the pair of left and right aerodynamic characteristic improvement devices 11L and 11R is determined as described above, their side surfaces 11a
Since the airflow flowing along the air is locally accelerated, separation of the boundary layer can be suppressed. Thereby, aircraft 1
Since the relationship between the sideslip angle of 0 and the yawing moment generated in the fuselage 2 can be made linear as shown in FIG. 7, it is possible to realize straightforward flight characteristics in which the body attitude does not fluctuate.

Further, since it is only necessary to mount a pair of left and right aerodynamic characteristic improving devices 11L and 11R on the left and right side surfaces 2L and 2R of the fuselage 2, respectively, the aircraft is not greatly changed without changing the outer shape and the internal structure of the fuselage 2. 10 can improve the aerodynamic characteristics.

Second Embodiment In the above-described first embodiment, a wedge-shaped aerodynamic characteristic improving device extending divergently toward the rear of the fuselage is provided with a fuselage 2.
On the left and right side surfaces 2L, 2R. On the other hand, as shown in FIG. 8, a pair of left and right projecting portions 21 </ b> L and 21 </ b> R extending in a direction perpendicular to the longitudinal axis CL of the vehicle is provided.
Left and right side surfaces 2L of the fuselage 2 of the aircraft 20 of the second embodiment,
Protruding from the rear end of the 2R causes stagnation 22L, 22R of the airflow, and the same effect as the aerodynamic characteristic improving device of the first embodiment can be obtained. In addition, a pair of left and right projecting portions 2
1L and 21R make the protrusion dimension with respect to the left and right side surfaces 2L and 2R of the body 2 and the dimension in the vertical direction equal to those of the aerodynamic characteristic improvement devices 11L and 11R of the first embodiment.

Third Embodiment In the first embodiment and the second embodiment described above,
Although the case where the fuselage 2 of the aircraft is narrowed in the width direction has been described, the aerodynamic characteristic improving device of the present invention can also be used when the fuselage 2 is narrowed down in the vertical direction toward the rear of the aircraft.

That is, in the aircraft 30 shown in FIGS. 9 and 10, a pair of right and left overhangs extending in the front-rear direction at the base of the main wing 4 and the horizontal tail 5 along the left and right side surfaces 2L and 2R of the fuselage 2. Parts 6L and 6R are provided. The overhangs 6L and 6R are provided on the upper surface 6L.
The space between the U and the lower surface 6S is gradually narrowed toward the rear of the fuselage so that the vertical distance between the U and the lower surface 6S is reduced. This may cause separation of the boundary layer at a portion of the upper surface 6U of the pair of left and right overhanging portions 6L, 6R whose inclination angle with respect to the fuselage longitudinal axis CL exceeds a specific angle.

Therefore, a pair of left and right aerodynamic characteristic improving devices 31L and 31R for preventing separation of the boundary layer are provided at the rear end of the upper surface 6U of the pair of left and right overhanging portions 6L and 6R. These aerodynamic characteristic improvement devices 31L and 31R are:
As shown in FIG. 11, it is formed as a wedge-shaped protruding portion extending divergently toward the rear of the fuselage, and its shape is the aerodynamic characteristic improving device 11 of the first embodiment described above.
L and 11R can be set in the same manner. Thereby, the relationship between the elevation angle of the aircraft 30 and the pitching moment generated in the fuselage 2 can be made linear as shown in FIG. 12, so that it is possible to realize straightforward flight characteristics in which the body attitude does not fluctuate. it can.

Although the embodiments of the aerodynamic characteristic improving apparatus for an aircraft according to the present invention have been described in detail above, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications are possible. No. For example, in each of the above-described embodiments, each aerodynamic characteristic improving device is disposed at the rear end of the fuselage 2 or the overhanging portions 6L and 6R, but any location where prevention of boundary layer separation is required. , Can be provided on any part of the body 2 or the overhang portions 6L, 6R.

[0028]

As is clear from the above description, when the aerodynamic characteristic improving device according to the present invention is mounted on the body surface, the airflow is locally accelerated and the separation of the boundary layer is suppressed. Non-linearity can be prevented. As a result, it is possible to improve the aerodynamic characteristics of the aircraft and realize straightforward flight characteristics in which the body attitude does not change. Further, the aerodynamic characteristic improving device according to the present invention can be mounted on the surface of the fuselage without significantly changing the outer shape and internal structure of the fuselage.

[Brief description of the drawings]

FIG. 1 is a plan view showing an aircraft according to a first embodiment of the present invention.

FIG. 2 is a left side view of the aircraft shown in FIG.

FIG. 3 is an exemplary perspective view showing a rear part of the aircraft shown in FIG. 1;

FIG. 4 is a rear plan view of the body illustrating a method of setting the shape of the aerodynamic additive;

FIG. 5 is a rear plan view of the body illustrating a method of setting the shape of the aerodynamic additional object.

FIG. 6 is a rear view of the aircraft shown in FIG. 1;

FIG. 7 is a graph showing the relationship between the sideslip angle of the airframe and the yawing moment.

FIG. 8 is a rear plan view of an aircraft body of an aircraft according to a second embodiment of the present invention.

FIG. 9 is a left side view showing an aircraft according to a third embodiment of the present invention.

FIG. 10 is a plan view of the aircraft shown in FIG. 9;

FIG. 11 is an exemplary perspective view showing a rear part of the aircraft shown in FIG. 9;

FIG. 12 is a graph showing a relationship between an elevation angle of a body and a pitching moment.

FIG. 13 is a plan view schematically showing the flow of air in the rear part of the body of a conventional aircraft.

FIG. 14 is a plan view schematically showing the flow of air at the rear of the aircraft when the aircraft slides to the right.

FIG. 15 is a graph showing the relationship between the sideslip angle of the airframe and yawing moment when boundary layer separation occurs in a conventional aircraft.

FIG. 16 is a graph showing the relationship between the elevation angle of the airframe and the pitching moment when boundary layer separation occurs in a conventional aircraft.

[Explanation of symbols]

 A Front end of aerodynamic additive B Rear end of aerodynamic additive 1 Conventional aircraft 2 Fuselage 2L Left side 2R Right side 3L, 3R Boundary layer separation 4 Main wing 5 Horizontal tail 6L, 6R Overhang 6U Upper surface 6S Lower surface 10 The aircraft 11L, 11R protrusion of the first embodiment (aerodynamic characteristic improvement device) 20 The aircraft 21L, 21R protrusion of the second embodiment (aerodynamic characteristic improvement device) 22L, 22R Air stagnation 30 of the present invention Aircraft 31L, 31R Projection of Third Embodiment (Aerodynamic Characteristics Improvement Device)

Claims (5)

[Claims] An aircraft having a wedge-shaped projection, which protrudes toward the rear of the fuselage and protrudes toward the rear of the fuselage and protrudes from a portion of the fuselage surface of the aircraft that is narrowed toward the rear of the fuselage. Aerodynamic characteristics improvement device. 2. The vehicle according to claim 1, wherein the projecting portion projects from the body surface with a front end of the body surface starting to incline at a predetermined angle or more with respect to a longitudinal axis of the body. An aerodynamic characteristic improving device for an aircraft according to claim 1. 3. The protruding portion, wherein a protruding height of a rear end of the protruding portion protruding from the body surface is set to a half of a thickness of a boundary layer formed on the body surface at a rear end position. Item 3. An aircraft aerodynamic characteristic improving apparatus according to item 1 or 2. 4. A plane-shaped protruding portion extending vertically and horizontally with respect to the longitudinal axis of the fuselage, protruding from a portion of the fuselage surface of the aircraft that is narrowed toward the rear of the fuselage. Aerodynamic characteristics improvement device for aircraft. 5. An aircraft equipped with the aircraft aerodynamic characteristic improving device according to claim 1.