KR20080019521A - Propeller fan - Google Patents

Abstract

A propeller fan capable of suppressing noise by suppressing growth of vane vortex and boundary layer is disclosed. In the propeller fan according to the present invention, a propeller fan having at least one blade curved to protrude toward the negative pressure side is provided in the hub, and the blade has a curved surface portion protruding toward the positive pressure side in a portion other than the rear edge in the rotational direction. The curved surface portion is configured to be positioned on the negative pressure side rather than the blade edge of the blade.

Description

Propeller Fan}

1 is a front view of a propeller fan according to a first embodiment of the present invention,

2 is a cross-sectional view taken along the line A-A of FIG.

3 is a pressure distribution diagram of the negative pressure surface of the propeller fan shown in FIG.

4 is a pressure distribution diagram of the positive pressure surface of the propeller fan shown in FIG.

5 is a front view of the propeller fan according to the second embodiment of the present invention,

6 is a cross-sectional view taken along the line A-A of FIG.

7 is a cross-sectional view taken along the line B-B of FIG.

8 is a cross-sectional view taken along the line C-C of FIG.

9 is a cross-sectional view taken along the line D-D of FIG. 5,

10 is a pressure distribution diagram of the negative pressure surface of the propeller fan shown in FIG. 5,

FIG. 11 is a pressure distribution diagram of the positive pressure surface of the propeller fan shown in FIG. 5.

* Description of symbols on the main parts of the drawings *

10..propeller fan 11..hub

12.Blade 12E.Negative pressure surface

12F. Positive pressure surface 13. Curved surface part

14..plate

The present invention relates to a propeller fan which rotates a hub provided with a curved blade so as to protrude toward the negative pressure side, and delivers a fluid such as air from the negative pressure side to the positive pressure side.

Propeller fans are used, for example, in outdoor units of air conditioners. The conventional general propeller fan is provided with the blade curved so as to protrude toward the negative pressure side. The pressure is changed from the front side to the rear side in the rotational direction of the blade to efficiently generate the pressure difference between the negative pressure side and the positive pressure side, and increase the air flow from the negative pressure side to the positive pressure side.

However, in the conventional blades, it is known that a flow, such as a wing tip vortex, which sucks the outer circumferential end of the blade due to the pressure difference between the positive pressure side and the negative pressure side at the outer circumferential end (wing end) of the blade is known. Noise is generated when such vane vortex collides with a bell mouse which partitions the suction side and the discharge side of another blade or propeller fan.

In addition, a boundary layer is generated between the surface and the flow of the blade, and the boundary layer is peeled off from the blade surface while gradually developing toward the rear side in the rotational direction of the blade. When the boundary layer is peeled off, a wide range noise is generated.

As a countermeasure against such noise, a change in the shape of the blade is proposed as follows (Patent Documents 1 to 3).

[Patent Document 1] Japanese Patent Laid-Open No. 2003-184792

[Patent Document 2] Japanese Patent Application Laid-Open No. 7-77189

[Patent Document 3] Japanese Patent Application Laid-Open No. 2004-124748

By the way, in the conventional propeller fan, what suppresses vane vortex (patent document 1) or suppresses the growth of boundary layer (patent document 2,3) is proposed, respectively, but the growth of vane vortex and boundary layer growth is proposed, respectively. No blade shape has been proposed which effectively suppresses the pressure at the same time.

Moreover, in patent documents 2 and 3, since the rotation direction front edge part of a blade protrudes largely to a positive pressure side, fluid flow in the rotation direction front side is inhibited, and fan efficiency falls. Here, the fan efficiency is a ratio of the conveyance amount (for example, air volume) of the fluid by the fan and the power of a motor or the like for rotating the fan. Increasing the rotational speed to secure the transport amount of the fluid, the noise becomes more loud.

The present invention is to solve the above-described problems, an object of the present invention to provide a propeller fan that can reduce the noise by suppressing the growth of the wing vortex and the boundary layer.

In order to achieve the above object, the propeller fan according to the present invention is a propeller fan provided with at least one blade curved to protrude toward the negative pressure side, the blade in the rotational direction of the blade except the edge The inflexion surface part which protrudes toward the positive pressure side part is formed, The said inflexion surface part is comprised so that it may be located in the negative pressure side rather than the blade | wing of the said blade. It is characterized by the above-mentioned.

The propeller fan of the above configuration is changed so that the flow of the blade surface (negative pressure surface) on the negative pressure side swirls at the inflection surface portion. Moreover, in the blade surface (static pressure surface) on the positive pressure side, it flows so that it may ride over a curved surface part, and a flow velocity will increase and a pressure will fall. As a result, the pressure difference between the negative pressure side and the positive pressure side becomes small in the curved surface portion. Since the vane vortex is generated by the pressure difference between the negative pressure side and the static pressure side, the growth of the vane vortex is inhibited at this inflection surface portion.

In addition, although the boundary layer gradually grows from the front side in the rotational direction on the negative pressure surface, the flow changes in the inflection surface portion projecting on the positive pressure side, so that the growth of the boundary layer is stopped. Thus, the boundary layer grows newly from the rear of the inflection surface portion. Moreover, even in the positive pressure surface, the boundary layer grows as it follows the positive pressure surface from the rear in the rotational direction of the curved surface portion.

Moreover, since the inflection surface part is comprised so that it may be located in the negative pressure side rather than the blade | wing of the said blade, the fluid flow from the rotation direction front side of a blade is not inhibited.

Moreover, since this inflection surface part is provided in the part except the rotation direction rear edge part of a blade, the fan efficiency can be maintained by designing the shape of the rotation direction rear edge part of a blade so that a pressure difference may be produced efficiently.

EMBODIMENT OF THE INVENTION Hereinafter, the propeller fan which is 1st Embodiment of this invention is demonstrated with reference to attached drawing. The propeller fan constitutes a blower provided in the outdoor unit of the air conditioner.

The propeller fan 10 includes a hub 11 that forms a cylindrical shape that is rotated in the rotational direction T around the rotation axis L, and a plurality (three) of blades 12 provided on the outer circumference of the hub 11. ).

The outer circumferential end 12A (wing end) of the blade 12 is configured to form an arc shape around the rotation axis L as shown in FIG. 1 when viewed in the rotation axis L direction.

In addition, the rear edge portion 12B of the rotational direction T of the blade 12 is curved such that the radial center portion protrudes toward the rearward direction of the rotational direction T when viewed from the rotational axis L direction, and faces radially outward. It is comprised so that it may face the rotation direction front side, and is comprised so that it may cross | intersect the outer peripheral end 12A (wing end) of the blade 12 at an obtuse angle.

In addition, the front edge portion 12C of the rotational direction T of the blade 12 is concavely curved toward the rear side of the rotational direction T in the rotational axis L direction, and faces radially outward. Therefore, it is comprised so that it may protrude toward a rotational direction front side, and it is comprised so that it may intersect with the outer peripheral end 12A (wing end) of the blade 12 at an acute angle.

As shown in FIG. 2, the blade 12 is curved so that it may protrude toward one side (lower side in FIG. 2) as seen from the outer peripheral side. For this reason, the angle formed by the virtual plane orthogonal to the rotation axis L and the rotational direction T of the blade 12 front edge portion 12C is the rear of the virtual plane and the blade 12 in the rotational direction T. It is smaller than the angle which the edge part 12B makes, and the upper side of the blade 12 becomes a positive pressure side in FIG. 2, and the lower surface of the blade 12 becomes a negative pressure side. That is, the blade 12 is curved so as to protrude toward the negative pressure side as a whole.

Moreover, the inflexion surface part 13 which protrudes toward the positive pressure side is formed in the center part of the rotation direction T of the blade 12. As shown in FIG. The vertex of the inflection surface portion 13 is a line connecting the front edge portion 12C of the rotational direction T of the blade 12 and the rear edge portion 12B of the rotational direction T, that is, the chord C. ) Is located on the negative pressure side.

The propeller fan 10 which has such a structure is rotated toward the rotation direction T about the rotation axis L, and a pressure difference generate | occur | produces in the upper side (static pressure side) and the lower side (negative pressure side) of the blade 12, Air is conveyed from the negative pressure side toward the positive pressure side.

Air from the front side of the rotation direction T flows along the surface of the blade 12 on the negative pressure side (on the negative pressure surface 12E and along the surface of the blade 12 and changes in a swirled manner in the inflection surface portion 13). The surface of the blade 12 on the side (the positive pressure surface 12F flows over the inflection surface portion 13 so that the flow rate increases and the pressure decreases.) As a result, the inflection surface portion 13 has a negative pressure side and a positive pressure side. The pressure difference becomes small.

The vane vortex generated by the pressure difference between the negative pressure side and the positive pressure side is inhibited from growth because the pressure difference becomes small at the inflection surface portion 13. Further, the vane vortex is divided into two parts in the rotational direction T front side and the rotational direction T rear side of the inflection surface portion 13, so that the vane vortex in the rotational direction T rear side is discharged in the discharge direction.

In addition, although the boundary layer grows gradually from the front side of the rotation direction T on the negative pressure surface 12E, the growth of the boundary layer is stopped by changing the flow in the inflection surface portion 13. Thus, the boundary layer grows anew from the rear of the rotational direction T of the curved surface portion 13. In addition, in the positive pressure surface 12F, the boundary layer grows from the rear of the inflexion surface portion 13 in the rotational direction T along the positive pressure surface 12F.

Moreover, since the inflection surface part 13 is comprised so that it may be located in the negative pressure side rather than the chord C of the said blade 12, the air flow from the front side of the rotation direction T of the blade 12 is the inflection surface part 13 Is not inhibited by).

In addition, since the curved surface portion 13 is formed at the center portion of the rotational direction T of the blade 12, the rear edge portion of the blade rotational direction T is formed to be turned to the positive pressure side so as to efficiently generate a pressure difference.

In the propeller fan 10 of such a structure, since the growth of vane vortex is inhibited by the inflection surface part 13, the noise by vane vortex can be suppressed.

In addition, since the growth of the boundary layer is stopped due to the change of the flow in the curved surface portion 13, the boundary layer does not grow significantly and peeling can be suppressed. In addition, since the boundary layer itself does not grow significantly, the energy in the case of peeling is also small. Therefore, the boundary layer can suppress the noise due to peeling.

Furthermore, since the air flow from the front side of the rotational direction T of the blade 12 is not impeded by the inflection surface portion 13, it is not necessary to increase the rotation speed in order to secure the air volume without lowering the fan efficiency. .

Further, since the vane vortex is divided into the rotational direction T front side and the rotational direction T rear side of the inflection surface portion 13, the vane vortex on the rear side of the rotational direction T is discharged in the discharge direction, so that the fan The efficiency can be improved.

3 shows the results of the pressure distribution calculation on the negative pressure surface 12E. 4 shows the results of the pressure distribution calculation on the positive pressure surface 12F. In the negative pressure surface 12E, it turns out that the space | interval of an isobar in the inflection surface part 13 does not change pressure significantly. In the positive pressure surface 12F, the isobars are positioned to form two peaks with the inflection surface portion 13 as a boundary, and the pressure of the inflection surface portion 13 is lower than that of the surroundings. Therefore, it is confirmed in the inflection surface part 13 that the pressure difference between the positive pressure surface 12F and the negative pressure surface 12E is small.

Next, the propeller fan 10 which is 2nd Embodiment of this invention is demonstrated. Here, the same components as in the first embodiment are denoted by the same reference numerals and detailed description thereof will be omitted.

Similar to the first embodiment, the propeller fan 10 has a cylindrical hub 11 which is rotated around the rotational axis L toward the rotation direction T, and a plurality of hubs provided in the outer peripheral portion of the hub 11 ( Three blades 12 are provided.

The blade 12 is curved to protrude downwardly as a whole when viewed from the outer circumferential side, and a curved surface portion 13 protruding toward the positive pressure side is formed at the center portion of the rotational direction T of the blade 12. And, as shown in Figure 6, the plate portion 14 extending to the outer peripheral end (12A) (tip) of the blade 12 to the rotational direction (T) front side than the curved surface portion 13 to form a flat plate Is formed. This plate part 14 is comprised so that it may incline a little with respect to the negative pressure side with respect to the chord C. As shown in FIG. In addition, the rotational direction T rear edge part 12B of the blade 12 is comprised so that it may turn back large.

In addition, although this inflection surface part 13 is located in the center part of the rotation direction T of the blade 12 on the outer peripheral side of the blade 12 like FIG. 6, as it faces the inner peripheral side of the blade 12, the blade ( It is comprised so that the rotation direction T of 12) may approach the front edge part 12C. As a result, the length of the rotation direction T of the flat plate portion 14 provided on the front side of the rotation direction T of the curved surface portion 13 is shortened little by little, and as shown in Fig. 9 at the inner circumferential end 12D of the blade 12, The flat plate portion 14 and the curved surface portion 13 are not formed to form a wing shape curved to the negative pressure side.

According to the second embodiment, the flat plate portion 14 is formed on the outer circumferential side of the blade 12 in which the vane vortex occurs, in the rotational direction T front side than the inflection surface portion 13. Also in (14), the pressure difference between the negative pressure side and the positive pressure side is small, and growth of vane vortex is suppressed. In addition, in the flat plate part 14, since the flow of the surface of the blade 12 does not change, peeling of a boundary layer is suppressed. Therefore, it is possible to suppress noise due to collision of vane vortex and peeling of boundary layer. At this time, the rear edge portion 12B of the rotational direction T of the blade 12 is configured to be largely flipped back, so that a wing vortex with a large pressure difference occurs at this portion, or the flow changes abruptly, resulting in peeling of the boundary layer. However, since the tip vortex and the boundary layer do not grow significantly, noise due to peeling of the tip vortex and the boundary layer can be suppressed.

In addition, since the flat plate portion 14 is formed in the shape of a flat plate extending to the outer circumferential end 12A (wing end) of the blade 12, not only from the front of the rotational direction T of the blade 12, but also from the outer circumferential side. In addition, the air flow can be facilitated to significantly improve the fan efficiency.

In addition, since the rear edge part 12B of the rotation direction T of the blade 12 is comprised so that it may be largely rolled back, fan efficiency can be fully ensured.

In addition, since the position of the inflection surface portion 13 is gradually changed from the outer circumferential side toward the inner circumferential side, the peeling size of the boundary layer on the surface of the blade 12 is changed so that the peeled flow is rotated in the direction of rotation of the blade 12 ( T) Even when it collides with the obstacle on the back side (for example, the other blade 12), periodic noise can be suppressed small.

In addition, in the inner circumferential side portion where the flow rate flowing through the surface of the blade 12 is small, noise is suppressed even when the boundary layer grows and peels off, so that it is a wing shape that efficiently generates pressure changes without providing the inflection surface portion 13. The fan efficiency can be improved.

Here, the pressure distribution calculation result in the negative pressure surface 12E is shown in FIG. 11 shows the results of pressure distribution calculation on the positive pressure surface 12F. In the negative pressure surface 12E, the pressure of the outer peripheral side part of the inflection surface part 13 is high. Moreover, in 12 F of positive pressure surfaces, the pressure of the outer peripheral side part of the inflection surface part 13 is low. Therefore, it is confirmed in the inflection surface part 13 that the pressure difference is small in the positive pressure surface 12F and the negative pressure surface 12E especially on the outer peripheral side.

As mentioned above, although the propeller fan which is embodiment of this invention was demonstrated, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of this invention.

Moreover, the apparatus provided with this propeller fan is not limited to the outdoor unit of an air conditioning apparatus, but is applicable also to other industrial equipment, such as a ventilation fan, and household appliances.

In addition, although the number of blades was demonstrated with three things, it is not limited to this, It is preferable to determine the number and arrangement | positioning of blades in consideration of the size of a propeller fan, a set air volume, etc.

According to the present invention, it is possible to prevent the growth of the wing vortex at the inflection surface portion and to suppress the development of the boundary layer, thereby preventing the generation of noise. In addition, since the flow from the front of the rotational direction of the blade is not inhibited by the inflection surface portion, it is possible to suppress a decrease in the efficiency of the fan and to reduce the noise without raising the rotational speed more than necessary.

Claims (3)

In the propeller fan provided with at least one blade curved to protrude toward the negative pressure side, The blade is provided with an inflexion surface portion protruding toward the positive pressure side in a portion excluding the rear edge in the rotational direction of the blade, The said inflection surface part is a propeller fan comprised so that it may be located in the negative pressure side rather than the blade | wing of the said blade. The method of claim 1, The propeller fan characterized by the above-mentioned part of a rotation direction front side being formed in flat form from the said inflection surface part. The method according to claim 1 or 2, The curved surface portion is a propeller fan, characterized in that it is formed to gradually approach the front rim portion in the rotation direction toward the inner circumferential side from the outer circumferential side of the blade.

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