JPH086712B2 - Blower - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a blower.

(Prior Art) Generally, as an air blower for an outdoor unit of an air conditioner, a centrifugal blower (see, for example, JP-A-57-68600), a mixed-flow blower, or an axial-flow blower (e.g. 4069
No. 3) has been adopted, but it can be said that there is room for improvement in any of these types of blowers in terms of quieting operating noise and improving blow performance, as will be described later.

(Problems to be solved by the invention) That is, for example, a centrifugal blower, as shown in FIG.
A plurality of parts are provided in the vicinity of the outer peripheral portion between the front shroud 32 arranged so as to face the suction port 35 provided in the casing (not shown) and the rear shroud 33 arranged so as to face the front shroud 32 at a predetermined interval. .. are arranged at predetermined intervals in the circumferential direction and are provided with an impeller 31.

By the way, it is generally known that the air flowing on the blade surface flows into the front end side of the blade 34 in a laminar flow state, and then transitions to a turbulent state through a transition state and flows to the trailing edge side of the blade. In this case, if the chord length along the streamline of the blade 34 is short, the transition layer region B reaches the trailing edge portion of the blade 34 as shown in FIG. Airflow in the transitional state
It is considered that the noise increases due to the interference with the Karman vortex generated on the rear end side.

Therefore, in the conventional general centrifugal blower or mixed flow blower, as shown in FIG. 16, the chord length Lc of the blade 34 is Lc.
Is set relatively large (that is, the turbulent boundary layer C at the blade surface is
Is formed), and the increase in noise due to the mutual interference between the Karman vortex and the air flow in the transition state is suppressed.

However, on the other hand, at the blade tip portion 34a located near the front shroud 32 of the blade 34, the blade tip flow has a tip streamline ft.
As shown in Fig. 5, the blade tip flow is likely to separate near the downstream end because it becomes a sharp curved flow, and this separation area becomes larger as the blade tip streamline ft becomes longer (that is, the chord length). As Lc becomes longer, the front shroud 32 needs to be extended largely to the inner diameter side, and as a result, the suction port
This is because the caliber of 35 is reduced and the peeling action on the back side is promoted). Therefore, simply increasing the chord length Lc, as shown by the broken curve L ₂ in FIG. 13,
Although the specific noise can be suppressed to some extent by suppressing the interference with the Karman vortex, the ventilation performance due to the separation is large (see the broken curve l ₂ ), and even if the reduction in the specific noise is subtracted, it is not necessarily a preferable structure.

On the other hand, the axial blower (generally called a propeller fan) has a plurality of blades around the boss 43 as shown in FIG.
······························································································· Composed. At the blade end portion 42a of the blade 42, as shown in FIG. 19 and FIG. 20, respectively, the intake air wraps around the fan guide 44 from the front end side of the fan guide 44. Since it flows into the outer peripheral edge portion, in this case as well, the same problem as in the case of the centrifugal blower or the axial flow blower occurs at the blade tip portion 42a of the blade 42.

That is, for example, as shown in the solid line in FIG. 19, when the axial length of the fan guide 44 is set to be short, the transition layer region B is maintained up to the trailing edge of the blade 42 as shown in FIG. As a result, the noise due to the interference of Karman vortices becomes large, and as shown by the broken curves L ₄ and l ₄ in Fig. 14, although the ventilation performance is maintained at a relatively high level, the noise becomes extremely high,
Not preferred. Further, when the axial length of the fan guide 44 'is increased as shown by the chain line in FIG. 19 in order to suppress such noise increase, interference with the Karman vortex in the transition state is prevented. Therefore, the chain curve in Fig. 14
As shown by L ₅ and l ₅ , the noise is relatively low, but
The blowing performance is significantly reduced, which is also not preferable.

Therefore, the present invention provides a blower that prevents the mutual interference with the Karman vortex in the transition state of the blade tip flow, and at the same time suppresses the separation phenomenon of the air layer as much as possible, and has good noise and blower performance. It was made as a sentence.

(Means for Solving the Problem) In the invention of the present application, as a concrete means for solving the problem, (I) In the invention according to claim 1, as illustrated in FIGS. A plurality of blades 4, 4, ... Are sequentially arranged at predetermined intervals in the circumferential direction between a front shroud 2 located on the 5 side and a rear shroud 3 facing the front shroud 2 at predetermined intervals. .., and the blades 4, 4, ... Are continuous with the blade front edge portion 4b extending substantially linearly in the blade width direction and the portion of the blade front edge portion 4b near the front shroud 2 and In a centrifugal or mixed-flow blower having a blade tip 4a that bends and extends downstream with respect to the leading edge 4b, the upstream edge of the blade tip 4a of each of the blades 4, 4, ... To the department
A turbulent flow promoting means X for promoting the turbulent flow of the blade tip flow flowing through the blade tip portion 4a is provided. (II) In the invention according to claim 2, the turbulent flow promoting means X is illustrated in FIGS. 8 to 12. As described above, in the axial flow type blower in which the fan guide 25 is arranged at the radially outer position of the impeller 21 having the plurality of blades 22, 22, ... While set to be smaller than the axial dimension in the outer peripheral portion of the impeller 21, the outer peripheral blade end 22a of each of the blades 22, 22, ... Is located at a position corresponding to the upstream side of the fan guide. twenty two
A turbulent flow promoting means (X) for promoting turbulence of the blade tip flow flowing through a is provided. (III) In the invention according to claim 3, in the blower according to claim 1 or 2, turbulence is provided. The flow promoting means X is attached to the wing tips 4a, 22a.
(IV) The invention according to claim 4 is characterized in that the upstream side edge portion of the blower is formed so as to be substantially along the blade tip streamline. The flow promoting means X is constituted by an uneven cutout portion 11 formed at an upstream side edge portion of the blade tips 4a, 22a, (V) In the invention according to claim 5, the invention according to claim 1 or 2 The turbulent flow promoting means X is characterized in that the turbulent flow promoting means X is composed of a concave portion or a convex portion 12 formed on the surfaces of the blade tips 4a and 22a.

(Operation) The following operation is obtained by adopting such a configuration in the present invention.

(I) In the blower according to claim 1, the blades 4.4, ... Are continuous with the blade leading edge portion 4b extending substantially linearly in the blade width direction and the portion of the blade leading edge portion 4b near the front shroud 2 and the blades. Since it has a blade tip 4a that bends and extends downstream with respect to the leading edge 4b, the blade chord length is the shortest at the blade tip 4a located near the front shroud, and therefore the transitional air flow. Mutual interference between the blade and the Karman vortex is most likely to occur in the blade tip flow that flows through the blade tip 4a, but a turbulent flow promoting means that promotes turbulence of the blade tip flow at the upstream edge of the blade tip 4a. By forming X,
The airflow that flows into the blade tip 4a in a laminar flow state becomes a turbulent state immediately after the inflow and the transition layer region is narrowed as much as possible, and for example, the chord length at this blade tip 4a is set to be small. Even in this case, the transition zone does not reach the rear edge of the blade.

Further, since the chord length can be set to be small, the air flow separation phenomenon at the blade tip portion 4a near the front shroud 2 can be suppressed as much as possible.

(Ii) In the blower according to the second aspect, the position of the outer peripheral blade end 22a of each blade 22, 22, ... Is directly upstream of the fan guide is a portion where an air flow circulates along the fan guide. Therefore, the chord length is the shortest, and therefore, similar to the blower according to claim 1, mutual interference between the transitional air flow and the Karman vortex is most likely to occur in the blade tip flow flowing through the blade tip 22a. By providing the turbulent flow promoting means X on the blade tip 22a, the air flow sucked in the laminar flow state from the front end side of the fan guide 25 to the blade tip 22a on the outer peripheral side of the blade 22 can promote the turbulent flow promotion. The turbulent flow is promoted by the means X and the transition layer region is narrowed as much as possible, and even if the chord flow is set small, the transition layer region does not reach the trailing edge of the blade.

Further, since the chord length can be set to be small, the air flow separation phenomenon at the blade tip 22a is suppressed as much as possible.

(Iii) In the blower according to claim 3, the above (i) and (i
In addition to the effect described in i), since the turbulent flow promoting means X is composed of the notch 10 formed substantially along the blade tip streamline, the air flow resistance can be suppressed as much as possible. The turbulence of the air flow can be promoted.

(Iv) In the blower according to claim 4, the above (i), (ii)
In addition to the described action, the turbulent flow promoting means X has the concave-convex cutout 11
Therefore, the turbulence of the air flow can be promoted in a wide range of the blade tips 4a and 22a.

(V) In the blower according to claim 5, the above (i), (ii)
In addition to the described action, the turbulent flow promoting means X is composed of the concave portions or the convex portions 12 formed on the surfaces of the blade tips 4a, 22a. It can be easily formed.

(Effects of the Invention) Therefore, according to the blower of each invention of the present application, the following effects are obtained.

According to the invention described in claim 1, in the centrifugal blower or the mixed flow blower, at the inflow portion of the blade tip portion 4a where the mutual interference between the air flow in the transition state and the Karman vortex having the shortest chord length is likely to occur. Due to the extremely simple and inexpensive structure of providing the turbulent flow promoting means X, it is possible to prevent the mutual interference with the Karman vortex in the transitional state of the air flow and greatly reduce the operating noise (the solid curve in FIG. 13). (Refer to L ₁ ), by reducing the chord length, it is possible to suppress the separation phenomenon of the air flow and obtain a high level of blowing performance (see the real curve l _{1 in} Fig. 13).

According to the second aspect of the present invention, in the axial-flow blower, turbulent flow is promoted in the inflow portion of the blade tip 22a, where the mutual interference between the Karman vortex and the air flow in the transition state with the shortest chord length is likely to occur. Due to the extremely simple and inexpensive structure of providing the means X, it is possible to prevent the mutual interference with the Karman vortices in the transitional state of the air flow and significantly reduce the operating noise (see the solid curve L _{3 in} FIG. 14). ), in which it is possible to suppress the peeling phenomenon of the air flow by shortening of the chord length to promote maintenance of the air blowing performance (see solid curve l ₃ of FIG. 13).

In addition to the effects described above, the blower according to claim 3 can promote the turbulence of the air flow in a state where the air flow resistance is suppressed as much as possible, which further reduces noise and blow performance. Can be expected to improve.

According to the blower of claim 4, in addition to the effects described above, turbulence of the air flow can be promoted in a wide range of the blade tips 4a, 22a, so that the noise can be further lowered and the blow performance can be improved. Can be expected.

According to the blower of claim 5, in addition to the effects described above, the turbulent flow promoting means X is composed of the concave portion or the convex portion 12 which can be easily formed. The manufacturing cost can be reduced as compared with the case where

(Embodiment) Preferred embodiments of the present invention with reference to the accompanying drawings First Embodiment FIG. 1 shows a main part of a centrifugal blower according to an embodiment of the invention described in claims 1 and 3 of the present application. In the figure, reference numeral 1 is an impeller that constitutes a main part of the centrifugal blower. This impeller 1 is provided between a front shroud 2 arranged so as to face a suction port 5 formed on a casing (not shown) side and a rear shroud 3 arranged on the back side of the front shroud 2 with a predetermined gap therebetween. A plurality of blades 4, 4, ... Are attached so as to straddle each other at predetermined intervals in the circumferential direction. Further, each of the blades 4, 4, ... Has a blade leading edge portion 4b extending substantially linearly in the blade width direction at its leading edge portion.
And a blade tip portion 4a which is continuous with a portion of the blade leading edge portion 4b close to the front face shroud 2 and which is bent and extends with respect to the blade leading edge portion 4b. Therefore, as a result of adopting such a blade structure, the chord length with respect to the air flow becomes the shortest at the blade tip 4a, and the mutual interference between the air flow in the transition state and the Karman vortex is most likely to occur at the blade tip 4a. .

Therefore, in this embodiment, the inventions described in claims 1 and 3 are applied, and the blade tips 4a (that is, chord chords) of the respective blades 4, 4, ... Near the front shroud 2 are applied. At the edge of the air inflow side where the mutual interference between the airflow in the transition state and the Karman vortex is the shortest, which is likely to occur, along the direction of the streamline ft of the blade tip flow flowing along the front shroud 2. To form a substantially V-shaped notch 10 (corresponding to the turbulent flow promoting means X in claim 1).

Thus, when the notch 10 is formed at the inflow side edge of the blade tip 4a, as shown in FIG. 17, the airflow flowing into the blade tip 4a in the laminar flow state is notched at the initial inflow. Since the flow is disturbed by the part 10, the flow becomes turbulent quickly through an extremely short transition state. For this reason, the laminar boundary layer area A and the transitional layer area B are shortened as compared with those of the conventional structure (see FIGS. 15 and 16).
Even if the chord length Lc at 4a is made short, its wing tip
A turbulent boundary layer is surely formed on the trailing edge side of 4a. Therefore, the airflow after passing through the blade tip 4a always interferes with the Karman vortex generated on the rear side of the blade tip 4a in a turbulent state, and for example, the airflow in the transition state as in the conventional case. The noise generation is suppressed as much as possible in comparison with the case where is directly interfering with the Karman vortex (
See the solid curve L _{1 in} Fig. 13).

On the other hand, since the chord length Lc can be shortened, the length of the front shroud 2 in the bending direction can be shortened accordingly, and the diameter of the suction port 5 can be increased. As a result, the negative pressure area, that is, the separation area, on the back side of the front shroud 2 is reduced, the deterioration of the air blowing performance due to the air flow separation is suppressed, and a higher air blowing performance than the conventional air blower is achieved. It can be expected.

That is, in this embodiment, the blade tip 22 of the blade 4 is
It is possible to reduce the operating noise of the blower and improve the blowing performance at the same time by the extremely simple and inexpensive means of forming the notch 10 at the inlet of a and using it as the turbulent flow promoting means X. Is.

Second Embodiment FIG. 2 shows an impeller portion of a centrifugal blower according to an embodiment of the invention described in claims 1 and 4 of the present application. The second embodiment is also a modification of the first embodiment, and the first embodiment has a substantially V-shaped notch 10 formed at the inlet of the blade tip 4a. In contrast to the turbulent flow promoting means X, the turbulent flow promoting means X is formed by forming a concave-convex (saw-toothed) notch 11 in the blade tip 4a.

As described above, the turbulent flow promoting means X is formed by the concave-convex cutouts 11.
In addition to the above, the same operational effects as in the case of the first embodiment can be obtained, but in addition to this, in addition to this, turbulence is wider in the direction perpendicular to the blade tip streamline. Since it can be promoted within the range, a higher noise reduction effect than that of the first embodiment can be expected.

Third Embodiment FIG. 3 shows an impeller portion of a centrifugal blower according to an embodiment of the invention described in claims 1 and 5 of the present application. The third embodiment should be referred to as a modification of the first embodiment, like the second embodiment.
In the embodiment, the substantially V-shaped notch 10 is formed at the inlet portion of the blade tip 4a, whereas the protrusion 12 protruding toward the front side surface in the rotational direction is formed at the blade tip 4a. This is the turbulent flow promoting means X.

When the turbulent flow promoting means X is constituted by the convex portion 12 as described above, it is needless to say that the same operational effect as the case of the first embodiment can be obtained. As compared with the case where the notch processing is required to form the turbulent flow promoting means X as in the second embodiment, the forming is simpler and the manufacturing cost can be suppressed accordingly.

In this embodiment, the turbulent flow promoting means X is composed of a convex portion projecting forward in the rotational direction, but in other embodiments, it may be composed of a concave portion. The same action and effect can be obtained.

Fourth Embodiment FIG. 4 shows a portion of an impeller of a mixed flow blower according to an embodiment of the invention described in claims 1 and 3 of the present application.
In the fourth embodiment, the blade tips of a plurality of blades 4, 4, ..., Which are arranged between the front shroud 2 and the rear shroud 3,
A substantially V-shaped notch 10 having the same structure as that of the first embodiment is formed at the inlet of 4a, and this is used as the turbulent flow promoting means X.

Therefore, in this embodiment, in the axial flow type in which the same blade tip flow as in the case of the centrifugal type blower is generated, though the type of the blower is different, the notch portion 10 is formed to form the above first embodiment. The same effect as in the case of
That is, it is possible to reduce the operating noise and improve the blowing performance.

Fifth Embodiment FIG. 5 shows a portion of an impeller of a mixed flow blower according to an embodiment of the present invention as set forth in claims 1 and 4 of the present application.
The fifth embodiment is also a modification of the fourth embodiment, in which the turbulent flow promoting means X is formed by a notch 11 having an uneven shape.

Therefore, in this embodiment, the same operation and effect as in the case of the first embodiment can be obtained, and at the same time, the same operation and effect as the second embodiment can be obtained.

Sixth Embodiment FIG. 6 shows a portion of an impeller of a mixed flow blower according to an embodiment of the present invention as set forth in claims 1 and 5 of the present application.
Similar to the fifth embodiment, this embodiment should be called a modified example of the fourth embodiment. In the fourth embodiment, the turbulent flow promoting means X is substantially V-shaped. Notch 10
The turbulent flow promoting means X is
The protrusion 12 is formed so as to protrude to the front side in the rotation direction of 4a.

Therefore, in the present embodiment, it is possible to obtain not only the function and effect of the first embodiment but also the function and effect of the third embodiment.

Seventh Embodiment FIG. 7 shows a portion of an impeller 1 of a mixed flow blower, which should be called a modification of the fifth embodiment. In all of the fourth to sixth embodiments of the present invention, the front shroud 2 is integrated with the impeller 1, whereas the front shroud 2 is separated from the impeller 1. It is a mixed flow blower of the type formed in.

Even in the case of such a configuration, the fourth
Similar to the embodiment, by forming the notch 10 as the turbulent flow promoting means X in the blade tip portion 4a of the blade 4, the same effect as in the case of the fourth embodiment can be obtained. In this case, instead of forming the substantially V-shaped notch 10 as in this embodiment as the turbulent flow promoting means X, the uneven notch 11 as shown in FIG. 5 or the notch 11 shown in FIG. Of course, it is possible to form such a protrusion 12.

Eighth Embodiment FIG. 8 shows a main part of an impeller 21 which is a main part of an axial flow fan according to an embodiment of the invention described in claims 2 and 3 of the present application. This vane wheel 21 has a plurality of substantially triangular blades 22 arranged at predetermined intervals around a boss 23 as shown in FIG. 8 and FIG. 9, and the outer sides of the blades 22, 22 ,. The fan guide 25 is attached so as to surround it. Also in this embodiment, the fan guide 25
At the blade tip portion 22a in the vicinity, since the blade tip flow flows from the outer peripheral side of the blade 22 diagonally across it (see the blade tip streamline ft), similar to the centrifugal blower or the mixed flow blower. , The blade chord length is the shortest at the blade tip 22a, and the mutual interference between the air flow in the transition state and the Karman vortex is most likely to occur, and there is a problem that the operation noise is increased or the blowing performance is deteriorated by the blade tip flow. There is something as described above.

Therefore, in this embodiment, the wing tip 22a is
By applying the invention described in claims 1 and 3 of the present application, a substantially V-shaped notch 10 is formed along the blade tip streamline ft, and this is used as the turbulent flow promoting means X.

By doing so, the flow of the blade tip flow is positively disturbed in the initial stage by the notch 10, and the laminar flow state is changed to the turbulent flow state at an early stage. As a result, it is possible to reliably prevent the blade tip flow from interfering with the Karman vortex on the trailing edge side of the blade in the transition state before reaching the turbulent layer, and the operation noise can be reduced accordingly.

In addition, since the wing tip flow is turbulent at an early stage,
The axial length of the fan guide 25, which had to be set to a relatively long dimension from the viewpoint of suppressing an increase in noise due to the delay in turbulence, can be set to a shorter length, and as a result,
It is possible to suppress the separation phenomenon of the blade tip flow as much as possible and obtain a higher air blowing performance.

Ninth Embodiment FIG. 10 shows an impeller 21 portion of an axial-flow type blower according to an embodiment of the invention described in claims 2 and 4 of the present application. This embodiment should be called a modification of the above-mentioned eight embodiments, and the eighth embodiment has a substantially V-shaped notch.
While the turbulent flow promoting means X was composed of 10,
The turbulent flow accelerating means X is constituted by a notch 11 formed by arranging a plurality of substantially V-shaped notches along the blade tip streamline ft.

Therefore, in this embodiment, it is of course possible to obtain the same operational effects as in the above-mentioned eighth embodiment, but in addition to this, the turbulent promotion of the blade tip flow by the notch 11 is promoted. Because it is done in a wider range,
Higher noise reduction and improved ventilation performance can be expected.

In FIG. 11, as a modified example of this embodiment, the notch 11 is replaced by a notch that is continuous in an inclined state, and a notch is formed in a direction substantially orthogonal to the radial direction of the blade 22. It is shown that it is composed of multiple consecutive cutouts,
In this case as well, substantially the same operational effects as described above can be obtained.

Tenth Embodiment FIG. 12 shows an impeller 21 portion of an axial flow fan according to an embodiment of the present invention as set forth in claims 2 and 5 of the present application.
In the embodiment, the turbulent flow promoting means X is formed by the notches in both the eighth and ninth embodiments, whereas the protrusion protruding toward the front side surface of the blade tip 22a in the rotation direction. The section 12 constitutes the turbulent flow promoting means X.

Also in this case, since the turbulent flow of the blade tip flow is promoted by the respective convex portions 12 and 12 similar to those in the above-mentioned respective embodiments, it can be expected that the operation noise is reduced and the air blowing performance is improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a centrifugal blower according to a first embodiment of the present invention, FIG. 2 is a vertical cross-sectional view of a main part of a centrifugal blower according to a second embodiment, and FIG. 3 is a third embodiment. FIG. 4 is a vertical cross-sectional view of a main part of a centrifugal blower according to an example, FIG. 4 is a vertical cross-sectional view of a main part of a mixed-flow blower according to a fourth embodiment, and FIG. 5 is a cross-sectional view of a mixed-flow blower according to a fifth embodiment. 6 is a longitudinal sectional view of an essential part of a mixed flow fan according to a sixth embodiment, and FIG. 7 is a longitudinal sectional view of an essential part of a mixed flow fan according to a seventh embodiment of the present invention. Is the 8th
9 is a longitudinal sectional view of an axial flow fan according to an embodiment, FIG. 9 is a view taken along the line IX-IX of FIG. 8, and FIG. 10 is a longitudinal sectional view of an axial flow fan according to a ninth embodiment. FIG. 11 is a longitudinal sectional view of a main part of an axial-flow blower according to a modification of the axial-flow blower shown in FIG. 10, and FIG. 12 is a vertical cross-section of a main part of an axial-flow blower according to the tenth embodiment. Figures 13, 13 and 14 are specific noise and static pressure characteristic diagrams of the blower, Figs. 15 to 17 are explanatory views of the flow state of the blade tip flow in the blade element cross section, and Fig. 18 is a conventional centrifugal blower. Fig. 19 is a vertical cross-sectional view of a main part of a conventional axial-flow blower.
The drawing is a view on arrow XX-XX in FIG. 1 ...... Wing wheel 2 ...... Front shroud 3 ...... Rear shroud 4 ...... Wing 4a ...... Wing tip 4b ...... Wing leading edge 5 ...... Suction port 10 ...... Notch (Turbulence promoting means X) 11 …… Notch (turbulent flow promoting means X) 12 …… Convex part (turbulent flow promoting means X) 21 …… Impeller 22 …… Blade 22a …… Blade tip 23 …… Boss 25 …… Fan guide

Claims (5)

[Claims] 1. A predetermined gap in the circumferential direction between a front shroud (2) located on the suction port (5) side and a rear shroud (3) facing the front shroud (2) with a predetermined gap. And a blade wheel (1) in which a plurality of blades (4,4, ...) Are sequentially arranged, and the blades (4,4, ..) extend substantially linearly in the blade width direction. (4b) and a blade tip (4a) which is continuous with the front shroud (2) of the blade leading edge (4b) and bends and extends downstream with respect to the blade leading edge (4b). A centrifugal or mixed-flow blower having a blade that flows through the blade tip (4a) at the upstream edge of the blade tip (4a) of each blade (4, 4, ...). A blower characterized by comprising turbulent flow promoting means (X) for promoting turbulence of the end flow. 2. An impeller (2) provided with a plurality of wings (22, 22, ...).
An axial flow type blower in which a fan guide (25) is arranged at a radially outer position of 1), the fan guide (25)
The axial dimension of the blades (21) is set to be smaller than the axial dimension of the outer peripheral portion of the impeller (21), while the blades (22, 22 ,.
) A turbulent flow promoting means (X) for promoting turbulence of the blade tip flow flowing through the blade tip (22a) at a position corresponding to the upstream side of the fan guide of the outer peripheral blade tip (22a). A blower characterized by being provided with. 3. The cutout portion according to claim 1 or 2, wherein the turbulent flow promoting means (X) is formed at an upstream edge of the blade tip portion (4a, 22a) substantially along a blade tip streamline. A blower characterized by comprising (10). 4. The turbulent flow promoting means (X) according to claim 1 or 2, wherein the turbulent flow promoting means (X) is composed of an uneven notch (11) formed at an upstream edge of the blade tip (4a, 22a). Blower characterized by. 5. The turbulent flow promoting means (X) according to claim 1 or 2, characterized in that the turbulent flow promoting means (X) is composed of a concave portion or a convex portion (12) formed on the surface of the blade tip portion (4a, 22a). Blower to do.