JP2013217236A - Air-blowing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air-blowing device capable of suppressing deterioration in performance due to blade tip vortexes which are separated from negative pressure surfaces of blades, even in a configuration where a periphery of the blade on a trailing edge side is surrounded by a bell-mouth ring.SOLUTION: An axial air-blowing device 1 includes a fan boss 3 with a rotational axis line 2, a plurality of blades 4 attached radially to a circumference of the fan boss 3, and an annual bell-mouth ring 5 arranged so as to surround the plurality of blades. The plurality of blades are each joined to the bell-mouth ring at a periphery on a rear side in a rotating direction of the blade, while the blades are in a non-joined state to the bell-mouth ring at the periphery on a front side in the rotating direction. The bell-mouth ring is provided to rotate integral with the plurality of the blades. The bell-mouth ring has, in a suction part thereof, vortex grooves 12 for keeping vortexes which are separated from blade tips toward a counter-rotation direction from negative pressure surfaces 4b of the blades.

Description

  The present invention relates to an air blower having a wing surrounded by a bell mouth ring on the outer periphery near the rear edge.

  In an axial blower in which the outer periphery near the leading edge in the direction of rotation of the blade is open to the suction space, a blade tip vortex is generated on the suction surface side of the outer periphery of the blade near the opened leading edge. The edge vortex separates from the suction surface of the wing when the outer peripheral edge overlaps the bell mouth ring. The detached vortex is unstable and stays at the suction port of the bell mouth ring, obstructs the suction flow to the blower, collides with the following wing, disturbs the flow around the wing, The vortex structure collapses between the blades, impeding the flow passing between the blades.

  In relation to such a problem, for example, there is one disclosed in Patent Document 1. In the blower disclosed in Patent Document 1, a warped part that warps toward the suction side is provided on the outer peripheral edge of the blade, and the width of the warped part is set to increase from the front edge side to the rear edge side. It was. In addition, due to the characteristics of the wing, the vortex diameter of the wing tip vortex is reduced to stabilize the vortex, and the wing tip vortex is unlikely to be detached from the suction surface of the wing. Was.

Japanese Patent No. 3629702 (pages 9 to 11, FIGS. 13 and 15)

  However, in the conventional blower described above, the release position can be shifted to the downstream side to some extent by devising the release of the blade tip vortex, but in the region where the outer peripheral edge of the blade is surrounded by the bell mouth ring, Since the entrainment flow from the pressure surface of the blade to the suction surface is reduced, the action of holding the blade tip vortex on the blade surface is weakened, and the blade tip vortex is separated from the blade surface.

  The present invention has been made in view of the above, and even in the configuration in which the outer periphery near the trailing edge of the blade is surrounded by the bell mouth ring, the air blowing performance is reduced by the blade tip vortex separated from the suction surface of the blade. It aims at providing the air blower which can be suppressed.

  In order to achieve the above-described object, a blower of the present invention is arranged so as to surround a fan boss including a rotation axis, a plurality of blades attached radially around the fan boss, and the plurality of blades. An annular bell mouth ring, and each of the plurality of wings is joined to the bell mouth ring at the outer periphery on the rear side in the rotational direction, and is not joined to the bell mouth ring on the outer periphery at the front side in the rotational direction. The bell mouth ring is provided so as to rotate integrally with the plurality of wings, and the bell mouth ring is formed in the suction portion from the suction surface of the wing toward the counter-rotating direction. It has a vortex groove that holds the vortex detached from the blade tip.

  According to the air blower of the present invention, the separation vortex separated from the suction surface of the blades prevents the airflow flowing between the blades and collides with the following blades, and the blowing performance is deteriorated by the blade tip vortex. Can be suppressed.

It is a perspective view of the axial blower concerning an embodiment of the invention. It is the top view which looked at the axial-flow ventilation apparatus which concerns on this Embodiment from the suction side. It is an expanded view of the cylindrical cross section of a wing | blade part. It is sectional drawing containing a rotating shaft line. It is sectional drawing containing a rotating shaft line. It is sectional drawing containing a rotating shaft line. It is a figure of the same aspect as FIG. 1 with which the state of the vortex was shown. It is sectional drawing containing the axis of rotation in which the state of the vortex was shown. It is sectional drawing containing the axis of rotation in which the state of the vortex was shown. It is sectional drawing containing the axis of rotation in which the state of the vortex was shown. It is sectional drawing containing the axis of rotation in which the state of the vortex was shown.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of a blower according to the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 shows an axial blower according to an embodiment of the present invention, and is a perspective view seen from the suction side. FIG. 2 is a plan view seen from the suction side. For convenience of explanation, the direction along the rotation axis 2 is defined as the height direction, and the suction side is defined as the upward direction.

  The axial-flow blower 1 of the present embodiment includes a fan boss 3, a plurality (three in the figure of the present embodiment) blades 4, and a bell mouth ring 5. Each of the plurality of blades 4 extends radially from the periphery of the fan boss 3 around the rotation axis 2. The bell mouth ring 5 is disposed so as to surround the outer periphery of each wing 4 near the lower side in the height direction.

  The discharge side surface (the surface facing the rotation direction 6) of the blade 4 is the pressure surface 4a, and the suction side surface which is the back side of the pressure surface is the negative pressure surface 4b. The peripheral edge of the blade 4 that separates the pressure surface 4a and the suction surface 4b is a boss joint edge 4c that is a joint portion of the fan boss 3, a bell mouth joint edge 4d that is a joint portion of the blade 4 and the bell mouth ring 5, and a rotational direction 6 A front edge 4e facing forward, a rear edge 4f facing the front edge and facing the opposite side of the rotational direction 6, a front outer periphery 4g facing the outside of the wing 4 and connecting the front edge 4e and the bellmouth joint edge 4d. Have.

  The bell mouth ring 5 has a cylindrical shape so as to connect the adjacent wings 4 to each other, and synchronizes with the plurality of wings 4 and the fan boss 3 (holding the same angular position). And the fan boss 3 is rotated together. A vortex groove 12 extends in the counter-rotating direction from the suction surface 4 b of the blade 4 at a suction side portion of the inner peripheral surface of the bell mouth ring 5.

  FIG. 3 is a diagram in which the blade cross section at the cylindrical cross section line A of FIG. 2 is developed in a plane. The section line is an imaginary line that extends in a circular arc at the position having the maximum radius in the region where the front edge 4e to the rear edge 4f of the blade 4 exist with the rotation axis 2 as the center.

  A position where the suction surface 4b is farthest from the chord line 7 connecting the leading edge 4e and the trailing edge 4f of the blade 4 is defined as a maximum warping position 8 at this radius. The present invention has a warped shape in which the maximum warp position 8 is positioned in the counter-rotating direction with respect to the chord line 7.

  4, 5, and 6 are cross-sectional views taken along a plane including the rotation axis of FIG. 2, and are cross-sections taken along the cross-sectional lines B, D, and F of FIG.

  The suction space 9 and the blowing space 10 are divided by a baffle plate 11. A slight gap is secured between the baffle plate 11 and the bell mouth ring 5 so that the bell mouth ring 5 can rotate. A radius Ra that is the maximum diameter of the front outer peripheral edge 4 g is larger than the innermost peripheral diameter Rb of the bell mouth ring 5.

  FIG. 4 (cross-section line B) is a cross-section at a position where the pressure surface 4a of the blade 4 and the bell mouth ring 5 are close but not joined. The suction portion 5 a of the bell mouth ring 5 has a bell mouth shape in which the diameter increases upward from the portion having the minimum inner peripheral diameter of the bell mouth ring 5.

  FIG. 5 (section line D) is a section in which the section of the wing 4 is located below the suction portion 5 a of the bell mouth ring 5. 6 (cross-sectional line E) is a cross-section at a position that is in the counter-rotating direction than FIG. 5 and does not include the bell mouth joint edge 4d.

  In the suction portion 5a of the bell mouth ring 5, a vortex groove 12 continuing from the suction surface 4b of the blade is formed. As can be seen from the figure, the vortex groove 12 is configured such that its width decreases and the depth decreases as it goes in the counter-rotating direction. Further, as can be seen from the fact that the vortex groove 12 does not appear in FIG. 4, the vortex groove 12 is formed so as to disappear before reaching the subsequent pressure surface 4a. That is, the rear end in the rotational direction of the vortex groove 12 terminates in front of the pressure surface 4a of the blade 4 adjacent to the rear side in the rotational direction. Further, the vortex groove 12 is defined by a concave surface.

  Thus, the wing 4 is joined to the bell mouth ring 5 on the outer periphery on the rear side in the rotational direction, and is not joined to the bell mouth ring 5 on the outer periphery on the front side in the rotational direction. In other words, the blade 4 is in a cantilever state in which the inner peripheral side is supported by the fan boss 3 in the section including the rotation axis 2 (see FIG. 4) with respect to the region on the front side in the rotational direction. It has a configuration. Further, the outer periphery of the wing 4 on the front side in the rotational direction is located on the windward side in the direction of the rotational axis 2 with respect to the suction portion 5a of the bell mouth ring 5 (see FIG. 4), that is, opened to the suction space 9. On the other hand, the outer periphery of the wing 4 on the rear side in the rotational direction is surrounded by the bell mouth ring 5.

  Next, the operation and action of the axial blower configured as described above will be described. In the axial blower 1, the fan boss 3, the blade 4, and the bell mouth ring 5 are rotated together by a driving force of a fan motor (not shown). As the blade 4 rotates, the gas in the region in which the blade 4 rotates is pushed out to the blowing space 10 by the pressure surface 4a. At the same time, the gas in the suction space 9 flows into the region where the blades 4 rotate from the surface formed by the rotation trajectory of the front edge 4e and the front outer peripheral edge 4g. In this way, an air flow is generated from the suction space 9 to the blowing space 10.

  A vortex generated at the blade tip will be described with reference to FIGS. FIG. 7 is a perspective view of the axial blower as viewed from the suction space, and FIGS. 8, 9, 10 and 11 are cross sections taken along the cross-sectional lines B, C, D and E of FIG. .

  In order to make the phenomenon easy to understand, the relative field is described based on the rotating wing 4 and the bell mouth ring 5. In addition, in the figure, only the blade tip vortex 13 and the separation vortex 14 for one blade are shown, but it is assumed that the other blades 4 are also not shown and vortices are similarly generated.

  In the region where the front outer peripheral edge 4g appears in the cross section including the rotation axis 2 (FIG. 8), a part of the gas that has flowed into the rotation region of the blade 4 is moved from the pressure surface 4a having a higher pressure than the surroundings to the front outer peripheral edge 4g. As a result, the flow is drawn into the suction surface 4b where the pressure is low. Based on this entrainment flow, a flow having a vortex structure called a blade tip vortex 13 is formed near the front outer peripheral edge 4g of the suction surface 4b. The blade tip vortex 13 grows as it moves downstream along the front outer peripheral edge 4g.

  In the region where the blade 4 contacts the bell mouth ring 5 (FIG. 9), the blade tip vortex 13 contacts the suction portion 5a of the bell mouth ring and leaves the suction surface 4b and moves to the vortex groove 12.

  In the region where the blade 4 is located below the vortex groove 12 (FIG. 10) and the region in the counter-rotating direction (FIG. 11), the separated blade tip vortex (that is, this is called the separation vortex 14). Is gradually weakened while passing through the vortex groove 12 and toward the subsequent wing 4. Therefore, it is possible to prevent the separation vortex from straying between the blades and hindering the flow between the blades due to the vortex breakdown. Thereby, the pressure | voltage rise performance of an air blower can be improved.

  Further, since the vortex groove 12 is a part of the bell mouth ring 5 and rotates together with the blade 4, the blade tip vortex can be prevented from being immediately carried to the subsequent blade 4 and colliding with it. For this reason, the separation vortex 14 does not collide with the subsequent blade 4 and the flow around the subsequent blade is not disturbed, so that the boosting performance is not lowered and the noise is kept low.

  Further, the pressure at the blade tip vortex 13 and the separation vortex 14 is lower than that of the surroundings, and a flow 15 that is caught in the blade tip vortex 13 is generated. Since it is located, many gas can be suck | inhaled from the radial direction outer side of the axial flow air blower 1, and the advantage which can raise the ventilation volume of the axial flow air blower 1 is also acquired.

  Furthermore, the separation vortex 14 guides the entrained flow to the radially outer side inside the bell mouth ring 5 by the winding direction of the vortex (counterclockwise in FIGS. 8 to 11). For this reason, the blade 4 works on the airflow at a portion with a large radius, and this also provides the advantage that the boosting performance is enhanced.

  Here, in order to move the blade tip vortex 13 from the blade suction surface 4b to the vortex groove 12, the positional relationship between the two is important. In the present embodiment, the radius Ra that is the maximum diameter of the front outer peripheral edge 4 g is larger than the minimum inner diameter Rb of the bell mouth ring 5. Therefore, it can be set as the positional relationship which the negative pressure surface 4b near the front outer periphery 4g and the vortex groove | channel 12 in the suction part 5a of a bell mouth ring continue. As a result, the blade tip vortex 13 can smoothly transition from the suction surface 4 b of the blade 4 to the vortex groove 12.

  The separation vortex 14 becomes a small vortex as the distance from the suction surface 4b of the blade 4 increases. In the present embodiment, the vortex groove 12 is reduced in depth and width as it extends rearward from the suction surface 4b. Therefore, since the vortex groove 12 becomes smaller as the vortex becomes smaller, the vortex can be kept stable and longer. Thereby, the suction effect by the separation vortex 14 can be enhanced. Further, as described above, the separation vortex 14 gradually becomes smaller and weaker with distance from the suction surface 4b. In the vicinity of the pressure surface, the surface without the vortex groove 12 can smoothly guide the suction flow from the outer periphery.

  In the present embodiment, as shown in FIG. 4 (FIG. 8), the vortex groove 12 disappears before the pressure surface 4 a of the subsequent blade 4. Therefore, there is also an advantage that the airflow from the outer periphery can be effectively sucked in the entire radial direction of the axial blower 1.

  As described above, in the axial blower of the present embodiment, the bell mouth ring is provided at least on the outer side near the trailing edge of the blade, and the deterioration of the blowing performance due to the blade tip vortex separated from the suction surface of the blade is suppressed. be able to. Further, by using the vortex separated from the blade tip as power for sucking air, it is possible to improve the blowing performance. In addition, these make it possible to realize a highly efficient blower with a small input for obtaining required air power.

  Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

  Examples of the application of the present invention include an axial blower used for an outdoor unit of an air conditioner and a ventilation fan for home use and business use. It can be widely applied.

  DESCRIPTION OF SYMBOLS 1 Axial flow blower, 2 Rotating axis line, 3 Fan boss, 4 Blade, 4a Pressure surface, 4b Negative pressure surface, 5 Bell mouth ring, 5a Suction part, 6 Rotation direction, 9 Suction space, 12 Swirl groove.

Claims (5)

A fan boss containing the axis of rotation;
A plurality of wings radially attached around the fan boss;
An annular bell mouth ring disposed so as to surround the plurality of wings,
Each of the plurality of wings is joined to the bell mouth ring on the outer periphery on the rear side in the rotational direction, and is not joined to the bell mouth ring on the outer periphery on the front side in the rotational direction.
The bell mouth ring is provided so as to rotate integrally with the plurality of wings,
The bell mouth ring has a vortex groove that holds a vortex separated from the blade tip in the counter-rotating direction from the suction surface of the blade at the suction portion thereof,
Blower device. The maximum diameter of the outer peripheral edge of each of the wings is larger than the minimum inner diameter of the bell mouth ring,
The air blower of Claim 1. The vortex groove is formed such that its depth and width become smaller as it extends from the suction surface of the blade.
The air blower of Claim 1 or 2. The vortex groove extends in the counter-rotating direction from the suction surface of the blade, and terminates before the pressure surface of the blade adjacent to the rear side in the rotation direction.
The air blower according to any one of claims 1 to 3. The outer periphery of each wing in the rotational direction front side is located on the windward side in the rotational axis direction from the suction part of the bell mouth ring, and is open to the suction space.
The air blower according to any one of claims 1 to 4.

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