JPH11280696A - Propeller fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a propeller fan which can increase the amount of wind without generating a boundary layer on vanes of the blade to cause detachment. SOLUTION: A plurality of through holes 3 are formed in respective four elements of a blade 2 of this propeller fan which is driven by a fan motor 1. This makes the fluid gushed out the through holes along the surface of the vanes of the propeller fan to supply energy to the fluid that has been decelerated in the boundary layer. Accordingly, detachment is prevented and uplifting power (a large amount of wind) can be obtained. The penetration holes are formed forward to the position where a detachment of the boundary layer of the air flow generates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial blower (propeller fan) used for an outdoor unit of an air conditioner or the like.

[0002]

2. Description of the Related Art An outdoor unit of an air conditioner includes an axial blower (hereinafter, referred to as a propeller fan), an outdoor heat exchanger, a compressor, and the like, and removes heat removed indoors during cooling operation. The cooling effect is obtained by radiating heat from the exchanger to the outside air, and the heating effect is obtained by radiating the heat pumped from the outside air by the heat exchanger into the room during the heating operation.

[0003] The propeller fan serves to promote convective heat exchange of the heat exchanger by sending outside air to the heat exchanger. Therefore, the propeller fan passes through the heat exchanger to improve the performance of the air conditioner. It is required to increase the air volume. As the propeller fan, one having three or five blades is generally used, but for the above-mentioned reason, increasing the air volume is one of the major goals of the propeller fan development.

[0004] Incidentally, a boundary layer is formed in the airflow on the blade surface of the propeller fan, and the boundary layer develops as the air flows on the blade surface, and the velocity gradient becomes large. The flow was disturbed, and it was in an unfavorable state for increasing the air volume.

[0005]

In the case of a propeller fan as well, a boundary layer is formed in the air flow on the surface of the blade, and the boundary layer develops as the air travels on the blade surface, and the velocity gradient becomes large. Eventually, peeling will occur and the smooth flow of the wind will be disturbed, resulting in an unfavorable condition for increasing the air volume. Therefore, the present invention provides a boundary layer on the blade surface of the blade of the axial flow fan It is an object of the present invention to provide an axial flow fan (propeller fan) capable of increasing the air flow without developing and causing separation.

[0006]

To achieve the above object, an axial blower according to a first aspect of the present invention is characterized in that a plurality of blades of the axial blower are provided with a low pressure from a high pressure surface. A configuration is adopted in which a through-hole is provided on the surface side so that fluid can be supplied.

According to a second aspect of the present invention, there is provided an axial blower, wherein a plurality of blades of the axial blower are provided with through holes so that fluid can be supplied from a high pressure side to a low pressure side.
The through hole was formed at a position in front of a position where separation of the boundary layer of the air flow was formed.

According to a third aspect of the present invention, there is provided an axial flow blower, wherein a plurality of blades of the axial flow blower are provided with through holes so that fluid can be supplied from a high pressure surface to a low pressure surface.
Alternatively, the through hole is formed at a position ahead of the position where the separation of the boundary layer of the air flow is formed, and the diameter of the through hole is 2 to 5 mm.
mm, and the area of all through holes is a blade.
1% or less of the wing surface.

In this manner, fluid is ejected from the through-hole along the blade surface of the propeller fan to supply energy to the decelerated fluid in the boundary layer, thereby preventing separation and obtaining a high lift (large air volume). .

[0010]

DETAILED DESCRIPTION OF THE INVENTION The reason why a boundary layer is formed in an air flow will be analyzed. If there is an object in the flow, there is an area near the object surface where the velocity of the fluid is reduced by the shear stress due to the viscosity of the fluid. The region where the fluid is flowing slowly is called a boundary layer, and the boundary layer is strongly affected by the pressure gradient along the object wall surface. And x along the object wall
If the y axis is perpendicular to the axis and the wall surface, the pressure gradient in the boundary layer is regarded as a function of only x with respect to the pressure p.
Only dp / dx need be considered.

The operation will be described with reference to FIG. This figure shows the relationship between the pressure gradient in the boundary layer along the wall surface and the shape of the velocity distribution for one curved surface, and the hatched portion in FIG. 3A is the object wall surface. Since the flow is accelerated in the range of dp / dx <0, the velocity distribution at points A and M is as shown by A and M in FIG.

Assuming that dp / dx> 0 downstream from the point M on the wall, the pressure gradually increases from this point, the flow in the boundary layer is decelerated, and finally the streamline is separated from the wall at the point S. When going further downstream, a backflow appears as at point B. This S point is called a separation point. If the flow is separated on the wall surface of the object, a vortex region is formed at the rear, which hinders a smooth flow of the fluid.

The present invention has been made by paying attention to the phenomenon of the flow in the boundary layer. The axial blower (propeller fan) of the present invention will be described with reference to a schematic diagram of a main part of the propeller fan of FIG. 1 is a fan motor, 2 is a blade of an axial blower (propeller fan), and in this example, 4 is a blade.
Shows one blade.

In the blade (blade) 2 of the axial blower (propeller fan), a plurality of through holes 3 are formed in each of the four blades for the above-described reason. As a result, the fluid was ejected from the through holes along the blade surface of the propeller fan, and energy was supplied to the decelerated fluid in the boundary layer, thereby preventing separation and obtaining a high lift (large air volume).

In order to prevent separation of the boundary layer, the through hole must be formed at a position in front of the position where the separation of the boundary layer of the air flow is formed. In the example of FIG. 1, the blade is formed at the front portion of the blade 2, but may be at a position behind the position where the separation of the boundary layer of the air flow is formed, as long as the position is at the front. In addition, an appropriate position range must be set in consideration of the operating speed of the fan.

Further, the diameter of the through hole is preferably about 2 to 5 mm in consideration of the restriction on the working operation. When the area ratio of the through hole is large, the through hole escapes from the pressure surface side to the negative pressure surface side. Since the wind increases and the air volume decreases, the area of all through holes is 1% of the blade surface of the blade.
Experiments have confirmed that the following is preferable.

Next, a through-hole is formed at the front edge of the blade (blade) 2 of the axial blower (propeller fan), the shape of the through-hole is round, and the rotation when operating at a rated speed of 600 rpm is performed. FIG. 2 shows the number-air volume characteristics. From this result,
About 3% increase in air volume was observed.

[0018]

As described above, the axial blower (propeller fan) of the present invention ejects a fluid from a high pressure side to a low pressure side through a through hole along a blade surface of a propeller fan, thereby forming a boundary layer. Energy can be supplied to the decelerated fluid inside to prevent separation from the blade surface and obtain a high lift (large air volume).

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of a propeller fan of the present invention.

FIG. 2 is a graph showing the relationship between the number of revolutions and the amount of airflow of a propeller fan according to the present invention.

FIG. 3 is a relationship diagram between a pressure gradient in a boundary layer and a shape of a velocity distribution.

[Explanation of symbols]

 1 Fan motor 2 Propeller fan blades 3 Propeller fan through hole

Claims (3)

[Claims] 1. A plurality of blades of an axial blower
An axial blower, wherein a through hole is provided so that a fluid can be supplied from a high pressure side to a low pressure side. 2. The axial blower according to claim 1, wherein the through hole is formed at a position ahead of a position where separation of the boundary layer of the air flow is formed. 3. The diameter of the through hole is about 2 to 5 mm, and the area of all the through holes is 1% of the blade surface of the blade.
The axial blower according to claim 1 or 2, wherein: