KR101275846B1 - Rotor blade with protruding trailing edge - Google Patents

Abstract

The present invention relates to a rotary blade having a protruding rear edge, the rotary blade coupled to the rotary shaft to generate a lift force, the rotary blade is coupled to the rotary shaft, has a shape extending in the radial direction of the rotary shaft, the direction of rotation A main body portion having an edge before and an edge before and opposite to the rotation direction; A front leading protrusion provided in front of the main body and protruding in the rotation direction; It is provided to the rear of the main body portion, and the rear front protrusion protruding in the opposite direction of the rotation direction.
According to the present invention, a pitching moment in the direction in which the leading edge is lifted up by reducing the strength of the vortex generated at the end by having the front leading protrusion projecting in the rotation direction and the rear leading protrusion projecting in the opposite direction to the rotation direction There is an effect that can be reduced.

Description

Rotor blade with protruding trailing edge

The present invention relates to a rotor blade having a protruding trailing edge, and more particularly to a rotor blade which can reduce the pitching moment in the direction of the leading edge upwards while the strength of the vortex generated at the tip is reduced.

The present invention is derived from a study conducted as part of the two-stage brain Korea 21 project of the Ministry of Education, Science and Technology and Pusan National University. [Task No .: Nuclear C6B1204, Project Name: Helicopter Parts Materials Core Research Manpower Training Project]

When the aircraft is flying at high speed in the air, a strong vortex occurs at the wing tip of the aircraft, which increases fuel consumption by increasing drag of the aircraft, and aerodynamic noise ( Noise is also known to increase.

In particular, a rotorcraft, such as a helicopter, a vertical short takeoff and landing (VSTOL), generates a lift by a plurality of rotor blades rotated by a rotating shaft connected to an engine. 1 is an example of such a rotor blade 1a. The rotary blade 1a is coupled to the rotary shaft H to generate lift, and has a rectangular planar shape extending in the radial direction of the rotary shaft H, and a leading edge that is an edge in the direction of rotation ( 2), a trailing edge 3 which is the opposite edge of the rotation direction, and a feathering axis F serving as a center of the pitch movement. Therefore, since the rotor blade 1a has a general rectangular planar shape, the blade tip speed of the rotor blade 1a becomes very large during high-speed flight, so that the vortex V generated at the end of the rotor blade 1a is increased. The above problems are more seriously raised, and the problem that the VVI noise generated by the collision of the vortex V generated at the end of the rotor blade 1a with the subsequent rotor rotor impinges on the rotor is also increased. There is this.

In order to solve the above problems, a rotor blade 1b, as shown in Fig. 2, was also used, which has a shape similar to a so-called British Experimental Rotor Program (BERP) rotor blade. The rotor blade 1b has a front leading protrusion 4 protruding in the rotational direction, and has a planar shape with a tapered end. By using the rotor blade 1b of this shape, the strength of the vortices generated at the end of the rotor blade during high-speed flight is reduced, and the high speed impulsive noise and the BVI noise generated by the shock wave are reduced to some extent. have.

However, since the rotor blade 1b includes the front leading protrusion 4 protruding in the rotational direction, the pitching moment in the direction in which the leading edge 2 is lifted up by the lifting force generated by the front leading protrusion 4 Pitching moment is generated, there is a problem that can cause a decrease in the structural stability of the overall blade rotor system (blade rotor system).

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a rotor blade having an improved structure so that the pitching moment in the direction ahead of the front can be reduced while the strength of the vortex generated at the end is reduced.

In order to achieve the above object, a rotary blade having a protruding rear edge according to the present invention is a rotary blade that generates lift by being coupled to a rotating shaft to be coupled to the rotating shaft to extend a shape extending in a rotational radial direction of the rotating shaft. A main body portion having a front edge that is an edge in a rotational direction and a rear edge that is in the opposite direction of the rotational direction; A front leading protrusion provided in front of the main body and protruding in the rotation direction; It is provided to the rear of the main body portion, and the rear front protrusion protruding in the opposite direction of the rotation direction.

Here, it is preferable that the pitching moment by the front leading protrusion and the pitching moment by the rear leading protrusion cancel each other.

Here, it is preferable that the starting position of the rear front protrusion is far away from the rotation axis by more than 50 points of the rotation radius (r / R = 0.5).

According to the present invention, a pitching moment in the direction in which the leading edge is lifted up by reducing the strength of the vortex generated at the end by having the front leading protrusion projecting in the rotation direction and the rear leading protrusion projecting in the opposite direction to the rotation direction There is an effect that can be reduced.

1 is a plan view showing a conventional rotor blade (rectangular planar shape).
Fig. 2 is a plan view showing a conventional rotor blade (plane shape with retreat angle).
3 is a plan view of a rotor blade having a protruding rear edge that is an embodiment of the present invention.
4 is a plan view for explaining a detailed shape of the rotor blade having a protruding rear edge shown in FIG.
5 is an exploded plan view of a rotor blade having the protruding rear edge shown in FIG. 4.
6 is a plan view of the virtual rotor blade illustrated in FIG. 4.
FIG. 7 is a plan view of a rotor blade simplifying the plane shape shown in FIG. 4. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a plan view of a rotor blade having a protruding rear edge which is an embodiment of the present invention, and FIG. 4 is a plan view illustrating a detailed shape of the rotor blade having the protruding rear edge shown in FIG. 3. 5 is an exploded plan view of a rotor blade having the protruding rear edge shown in FIG. 4.

3 to 5, the rotor blade 100 having a protruding rear edge according to a preferred embodiment of the present invention is a rotor blade that generates lift by being coupled to a rotation shaft H to rotate. The part 13, the front advance part 14, and the rear advance part 15 are comprised.

The main body 13 is a portion extending in the radial direction of rotation of the rotation shaft (H), has a rectangular planar shape having a length of C, one end is coupled to the rotation shaft (H), the other end It has a tapered shape. The main body portion 13 is formed of an airfoil in which a cross section perpendicular to the rotational radial direction generates lift, the leading edge 11 that is the edge in the rotational direction, and the direction opposite to the rotational direction. The rear edge 12 which is an edge is provided. That is, the main body portion 13 has the same shape except for the tapered portion of the end portion when compared with the virtual rotary blade AP shown in FIG. 6. Here, the virtual rotary blade AP is a virtual rotary blade introduced to explain the shape of the rotary blade 100 provided with the protruding rear edge, and in principle, a plane shape that is as close as possible to the shape of the main body portion 13. Has

Therefore, the initial demonstration length of the main body 13, that is, the length from the front edge 11 to the rear edge 12 at the point closest to the rotation axis H has the value of C.

The front leading protrusion 14 is provided at the front edge 11 of the main body 13 and is a portion protruding in the rotation direction. Therefore, the front edge 11 of the main body portion 13 and the edge in the rotation direction of the front edge protrusion 14 form the front edge of the rotary blade 100 having the protruding rear edge.

As shown in FIG. 4, the front leading protrusion 14 starts at a position spaced apart from the rotation shaft H by L (ie, a point of r = L), and protrudes at a point of r = L + P1. It has a length T1 and is formed over the space | part spaced apart from the said rotating shaft H by L + P1 + P2 (that is, the point of r = L + P1 + P2).

The rear front protrusion 15 is provided at the rear front 12 of the main body 13 and protrudes in the direction opposite to the rotation direction. Accordingly, the rear edge 12 of the main body 13 and the edge opposite to the rotation direction of the front edge protrusion 14 form the rear edge of the rotary blade 100 having the protruding rear edge.

As shown in FIG. 4, the rear anterior protrusion 15 starts at a position spaced apart from the rotation axis H by M (ie, a point of r = M), and protrudes at a point of r = M + P3. It has a length T2 and is formed over the space | part which is spaced apart from the said rotating shaft H by M + P3 + P4 (namely, r = M + P3 + P4). Accordingly, the maximum protrusion point (r = M + P3) of the rear front protrusion 15 is spaced apart from the end of the rotor blade 100 by a predetermined interval r = RM-P3 in the direction of the rotation axis H. It becomes a state.

In the present embodiment, the starting position (r = M point) of the rear protruding portion 15 is far away from the rotation axis H by more than 50 points of the rotation radius (r / R = 0.5). have. That is, M has a value of 0.5R or more.
The rear protruding portion 15 has a maximum length T2 protruding in the direction opposite to the rotation direction of 30% to 60% of the average demonstration. Here, the average demonstration is defined as a demonstration of a rectangular blade converted to have the same rotation radius and plane area as the rotor blade 100, in this embodiment has a value slightly larger than the value of C shown in FIG. .
The main body 13, the front leading protrusion 14 and the rear leading protrusion 15 are formed integrally with each other so as not to rotate relative to each other, and cooperate with each other at respective points r spaced apart from the rotation shaft H. Streamline airfoils are formed continuously. That is, in the rotor blade 100 having the protruding rear edge, the main body 13, the front edge protrusion 14, and the rear edge protrusion 15 are integrally formed to form a single rotary blade.

In the present embodiment, the pitching moment due to the lifting force generated in the rear tip protrusion 15 has a dimension and a shape that can be canceled with the pitching moment due to the lifting force generated in the front tip protrusion 14. The size and shape of the rear protruding portion 15 may be adjusted to values such as P3, P4, and T2. In FIG. 7, an area S1 obtained by triangulating the planar area of the front anterior protrusion 14 and an area S2 of the planar area of the rear anterior protrusion 15 triangularly is illustrated. By using (S1, S2), it is easy to aerodynamically calculate the lifting force generated in the front leading protrusion 14 and the rear leading protrusion 15, and the pitching moment due to the lifting force.

Hereinafter, the principle that the pitching moment is canceled will be described. The lifting force generated in the front anterior protrusion 14 is referred to as L1, and the distance from the feathering axis F to the point away from the feathering axis F is a, and the lifting force generated in the rear front protrusion 15 is similarly. Is L2, and the distance between the center of the lift force and the point away from the feathering axis F is b, the lift force L1 and the pitching moment M1 generated by the front leading protrusion 14 and the rear leading protrusion ( Lifting force L2 and pitching moment M2 generated by 15) are as follows.

L1 = 1 / 2ρC _l1 V1 ² S1 equation (1)

L2 = 1 / 2ρC _l2 V2 ² S2 equation (2)

M1 = L1 × a Equation (3)

M2 = L2 × b equation (4)

S1 = 1/2 (P1 + P2) T1 Expression (5)

S2 = 1/2 (P3 + P4) T2 equation (6)

Here, S1 and S2 mean an area obtained by triangulating the planar areas of the front anterior protrusion 14 and the rear anterior protrusion 15, respectively, wherein ρ is an air density and C ₁ is the front anterior protrusion 14. The lift coefficient of), C _l2 means the lift coefficient of the rear leading protrusion 15, V1 means the air velocity flowing in the front leading protrusion 14, V2 is the air flowing in the rear leading protrusion 15 Means speed.

On the other hand, since the values of M1 and M2 are the same, from equation (3) and equation (4),

L1 × a = L2 × b Equation (7)

Is derived, substituting Equation (1), Equation (2), Equation (5) and Equation (6) into Equation (7),

1 / 2ρC _l1 V1 ² × 1/2 (P1 + P2) T1 × a = 1 / 2ρC _l2 V2 ² × 1/2 (P3 + P4) T2 × b Formula (8)

This is derived.

Meanwhile,

V1 = Ω (L + P1) Equation (9)

V2 = Ω (M + P3) Equation (10)

Since the relationship between the C _l1 Assuming that the values of and C _l2 are the same, Equation (8) is derived as follows. Here, Ω means the rotational angular velocity of the rotation shaft (H).

(L + P1) ² × (P1 + P2) T1 × a = (M + P3) ² × 1/2 (P3 + P4) T2 × b Equation (11)

Therefore, when variables L, P1, P2, T1, and a related to the dimensions and shape of the front anterior protrusion 14 are determined, the pitching moment generated by the lift generated in the rear front protrusion 15 is the front front protrusion 14 The values of the variables M, P3, P4, T2, and b related to the dimensions and the shape of the rear protruding portion 15 may be determined so as to cancel each other with the pitching moment caused by the lift force generated in the cross section.

The rotor blade 100 having the protruding rear end described above has a front anterior projection 14 protruding in the rotational direction and a rear anterior projection 15 protruding in the opposite direction of the rotational direction. While the strength of the vortex is reduced by the front leading protrusion 14, the pitching moment in the direction in which the front leading edge 11 caused by the front leading protrusion 14 is lifted up can be reduced by the rear leading protrusion 15. There is an advantage. Therefore, the rotor blade 100 having the protruding rear edge has an advantage of preventing the deterioration of structural stability of the blade rotor system caused by the pitching moment in the direction in which the front edge 11 is lifted up. have.

In addition, the rotor blade 100 having the protruding rear edge is a point at which the starting position M of the rear front protrusion 15 is spaced 50% of the rotation radius from the rotation shaft H (r / R =). 0.5 or more), the air velocity V1 flowing in the rear protruding portion 15 may have a sufficient size, so that the pitching moment M2 generated by the rear protruding portion 15 may be generated to a sufficient size. There is an advantage.

In the present embodiment, the size and shape of the rear protruding portion 15 are determined so that the values of M1 and M2 are completely equal, but the values of M1 and M2 are not completely the same, but the pitching moment can be offset to some extent. Of course, it is also possible to determine the dimensions and shape of the rear front protrusion 15.

The technical scope of the present invention is not limited to the contents described in the above embodiments, and the equivalent structure modified or changed by those skilled in the art can be applied to the technical It is clear that the present invention does not depart from the scope of thought.

[Description of Reference Numerals]
100: rotor blade with protruding rear edge 11: front edge
12: rear front 13: body
4, 14: front anterior projections 15: rear anterior projections
H: axis of rotation F: feathering axis
V: Vortex AP: Virtual Rotary Wing

Claims (3)

In the rotor blade coupled to the rotary shaft to generate a lift by rotating,
A main body portion coupled to the rotation shaft, the main body portion having a shape extending in the radial direction of the rotation shaft, the front edge being the edge in the direction of rotation, and the trailing edge in the direction opposite to the direction of rotation;
A front leading protrusion provided in front of the main body and protruding in the rotation direction;
It is provided at the rear of the main body portion, protruding in the opposite direction of the rotation direction, and the rear front projections are spaced apart by a predetermined interval in the direction of the rotation axis from the end of the main body portion,
The pitching moment by the front leading protrusion and the pitching moment by the rear leading protrusion cancel each other,
The starting position of the rear protruding portion is far away from the rotation axis by more than 50 points of the radius of rotation (r / R = 0.5),
The rear protruding portion has a maximum length projecting in the direction opposite to the rotation direction of 30% to 60% of the average demonstration.
The main body portion, the front anterior projections and the rear anterior projections are formed integrally with each other so as not to rotate relative, and cooperate with each other to form a streamlined airfoil continuously at each point spaced apart from the rotation axis Equipped rotorcraft. delete delete

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