JP2013053533A - Axial flow blower and air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an axial flow blower capable of improving fan performance, and an air conditioner including the same.SOLUTION: The axial flow blower 10 includes: an impeller 20 which has a plurality of blades 21 provided around a rotary shaft A and a ring part 22 provided integrally with the plurality of blades 21 along outer peripheral edges of the plurality of blades 21; and a partition part 30a which is arranged with a clearance from the ring part 22 in such a manner as to surround an outer periphery of the ring part 22 and which partitions an air channel. A plurality of dimples 24 arranged in a circumferential direction are provided on an inner peripheral surface 22s of a suction-side area 22a of the ring part 22.

Description

  The present invention relates to an axial blower and an air conditioner.

  Conventionally, axial fans are used for applications such as air conditioners. The axial blower includes an impeller having a plurality of blades provided radially around a rotation shaft, and a bell mouth as a partition that partitions an air flow path. The bell mouth is disposed so as to surround the outer periphery of the impeller. In such an axial blower, an air vortex (blade tip vortex) may be generated near the outer periphery of the blade. This blade tip vortex causes a large pressure loss, and there is a problem that the fan performance cannot be sufficiently exhibited.

  Then, the technique which suppresses generation | occurrence | production of a blade tip vortex is proposed by using the impeller which has the cylindrical ring part provided integrally with the several blade | wing along the outer peripheral edge part of the several blade | wing. (For example, patent document 1).

JP 2008-223625 A

  However, when an impeller having the ring portion as described above is used, a phenomenon occurs in which air flows backward in a gap (tip clearance) between the ring portion and the bell mouth. That is, this reverse flow flows in the direction opposite to the direction of the main flow passing through the inner region of the ring portion. When such a reverse flow occurs, the main flow passes through the impeller while entraining the reverse flow, and thus a large separation occurs at the tip of the suction side region in the ring portion. In particular, in the semi-open type axial blower, the suction side of the outer peripheral portion of the impeller is opened without being surrounded by the bell mouth, so that air easily flows into the impeller from this open region. Therefore, in the semi-open axial blower, the main flow is likely to involve a reverse flow, and as a result, peeling is likely to occur at the tip of the suction side region in the ring portion.

  In addition, since the centripetal flow (flow near the rotation axis) is dominant in the impeller having the ring portion compared to the impeller having no ring portion, the flow separated at the tip of the suction side region Is difficult to reattach to the inner peripheral surface of the ring part. Thus, in the area | region which has not reattached to the internal peripheral surface of a ring part, since a blade | wing is not given a load with respect to a fluid, fan performance falls.

  Then, this invention is made | formed in view of this point, The place made into the objective is to provide the axial-flow fan which can improve fan performance, and an air conditioner provided with the same.

  (1) The axial blower of this invention is equipped with the impeller (20) and the partition part (30a). The impeller (20) is integrated with the plurality of blades (21) around the rotation axis (A) and the plurality of blades (21) along the outer peripheral edge of the plurality of blades (21). And a ring portion (22) that is provided. The partition part (30a) is arranged with a predetermined gap from the ring part (22) so as to surround the outer periphery of the ring part (22). The partition (30a) defines an air flow path. A plurality of dimples (24) arranged in the circumferential direction are provided on the inner peripheral surface (22s) of the suction side region (22a) of the ring portion (22).

  In this configuration, by providing a plurality of dimples (24) arranged in the circumferential direction on the inner peripheral surface (22s) of the suction side region (22a) of the ring portion (22), peeling is suppressed and fan performance is improved. be able to. That is, the separation of air is suppressed by separating the air flowing in a laminar flow state into a turbulent state by a plurality of dimples (24) at the tip of the suction side region (22a) of the ring portion (22). . Specifically, it is as follows.

  The plurality of dimples (24) cause turbulent flow in the air flowing in the vicinity thereof, so that the mixing of the air flowing in the vicinity of the dimple (24) and the surrounding air is promoted. Thereby, the air peeled off at the tip of the suction side region (22a) of the ring portion (22) can easily flow along the vicinity of the inner peripheral surface (22s) of the suction side region (22a), and the suction side region ( It becomes easy to reattach to the inner peripheral surface (22s) of 22a). Therefore, separation of air sucked into the impeller (20) is suppressed, and fan performance can be improved.

  (2) In the axial blower, when the suction side region (22a) has a flare shape, the main flow is likely to involve a reverse flow, and peeling is more likely to occur at the tip of the suction side region in the ring portion. Become. Therefore, in the case of such a flare shape, the peeling suppression effect by providing a plurality of dimples (24) on the inner peripheral surface (22s) of the suction side region (22a) can be obtained more remarkably.

  (3) In the axial fan, the plurality of dimples (24) are arranged on the condition that the diameter (D) of each dimple (24) is larger than the distance (G) between adjacent dimples (24). It is preferable. As described above, the plurality of dimples (24) are arranged relatively densely on the inner peripheral surface (22s) of the suction side region (22a), whereby the effect of suppressing peeling can be further enhanced.

  (4) In the axial fan, each dimple (24) preferably has a concave shape that is smoothly curved. As described above, since the shapes of the plurality of dimples (24) are arranged in a concave shape, the inner surface (22s) of the suction side region (22a) can provide a peeling suppression effect with little variation in the circumferential direction.

  (5) The air conditioner of the present invention is characterized in that the axial blower is used as a blower for an outdoor unit.

  As described above, according to the present invention, since the plurality of dimples arranged in the circumferential direction are provided in the suction side region on the inner peripheral surface of the ring portion, fan performance can be improved.

It is sectional drawing which shows the outdoor unit of the air conditioner provided with the axial flow fan which concerns on one Embodiment of this invention. It is a rear view which shows the impeller of the said axial flow fan. It is the figure which expanded the area | region (ring part) enclosed with the dashed-two dotted line in FIG. It is the perspective view which expanded the ring part of the said impeller. (A) is a schematic diagram for explaining the diameter of the dimple provided in the ring portion and the distance between the dimples, and (B) is a schematic diagram for explaining the diameter and depth of the dimple. . (A) is a schematic diagram which shows the flow of the air in the axial blower which concerns on the said embodiment, (B) is a schematic diagram which shows the flow of the air in the axial blower of the reference example in which the dimple is not provided. is there. It is a graph which shows the result of having compared the characteristic of the axial flow fan which concerns on the said embodiment, and the characteristic of the axial flow fan in which the dimple is not provided, and has shown the relationship between a flow coefficient and a static pressure coefficient. It is a graph which shows the result of having compared the characteristic of the axial flow fan which concerns on the said embodiment, and the characteristic of the axial flow fan in which the dimple is not provided, and has shown the relationship between a flow coefficient and a specific noise. It is a graph which shows the result of having compared the characteristic of the axial flow fan which concerns on the said embodiment, and the characteristic of the axial flow fan in which the dimple is not provided, and has shown the relationship between a flow coefficient and a total pressure efficiency. It is the schematic which shows the modification of the said ring part.

  Hereinafter, an axial blower 10 according to an embodiment of the present invention and an outdoor unit 40 of an air conditioner including the same will be described with reference to the drawings. As shown in FIG. 1, the outdoor unit 40 includes a casing 41, a heat exchanger 42, and the axial flow fan 10. The casing 41 is provided with an air inlet 43 and an air outlet 44. The heat exchanger 42 has a shape extending in the vertical direction, and is disposed on the air inlet 43 side in the casing 41. A grill 45 is attached to the air outlet 44.

  The axial blower 10 includes an impeller 20, a bell mouth 30, and a fan motor 11. The axial blower 10 is a semi-open axial blower. That is, in the axial blower 10, the bell mouth 30 surrounds the blowout side (left side in FIG. 1) in the outer peripheral portion of the impeller 20, and the suction side (right side in FIG. 1) in the outer peripheral portion of the impeller 20. Is not surrounded by the bellmouth 30 and is open.

  The fan motor 11 is attached to the grill 45. The fan motor 11 has a shaft 12 that rotates about a rotation axis A.

  As shown in FIGS. 1 and 2, the impeller 20 includes a hub 23 fixed to the shaft 12, a plurality of blades 21 extending radially outward from the outer peripheral surface of the hub 23, and an outside of the plurality of blades 21. It has the ring part 22 provided integrally with the some blade | wing 21 along the peripheral part 21a.

  The ring part 22 has the suction part 22a located in the suction side area | region, and the blowing part 22b located in the blowing side area | region. The blow-out portion 22b has a cylindrical shape with a constant inner diameter, and faces the inner peripheral surface of the partition portion 30a of the bell mouth 30 described later in the radial direction. The inner peripheral surface of the blowing part 22 b is connected to the outer peripheral edge part 21 a of each blade 21. Air is blown out from the opening at the end of the blowing portion 22b.

  The suction part 22a is a part that extends from the blowing part 22b to the upstream side of the airflow, and has a flare shape that increases in diameter toward the upstream side of the airflow. The periphery of the suction portion 22a is not surrounded by the bell mouth 30. The inner peripheral surface of the suction part 22 a is separated from the outer peripheral edge part 21 a of each blade 21.

  The bell mouth 30 is attached to the front plate 41 a of the casing 41. The bell mouth 30 is integrated (modularized) with the grill 45, the fan motor 11, and the impeller 20, and then attached to the front plate 41a.

  The bell mouth 30 has a flat plate portion 30 b extending in parallel with the front plate 41 a and a partition portion 30 a that partitions a circular air outlet 44. The partition part 30 a is arranged with a predetermined gap from the ring part 22 so as to surround the outer periphery of the ring part 22. The upstream portion of the air flow in the partition portion 30a has a cylindrical shape with the inner diameter of the inner peripheral surface being substantially constant, and the downstream portion of the air flow in the partition portion 30a is directed toward the downstream side. It has a flare shape in which the inner diameter of the inner peripheral surface increases.

  In such an axial blower 10, when the impeller 20 is rotated by the fan motor 11, external air is sucked into the casing 41 from the air suction port 43. The sucked air exchanges heat with the refrigerant in the heat exchanger 42, then proceeds in the direction of the two-dot chain line arrow in FIG. 1, and is blown out of the casing 41 through the air outlet 44.

  Next, the configuration of the ring portion 22 will be described in detail. A plurality of dimples 24 are provided on the inner peripheral surface 22 s of the suction portion 22 a of the ring portion 22. The plurality of dimples 24 are not provided in the blowing portion 22b. The plurality of dimples 24 are formed in almost the entire area of the flare-shaped inner peripheral surface 22s. The plurality of dimples 24 are arranged in the circumferential direction and also in the air flow direction.

  As shown in FIGS. 5A and 5B, each dimple 24 has a concave shape that is smoothly curved (a concave shape such as a part of a spherical surface). The shape of the opening of each dimple 24 is substantially circular. The diameter D at the opening of each dimple 24 is larger than the distances G1, G2, G3 between adjacent dimples. The diameter D of each dimple 24 is larger than the depth H (H / D <1). In this embodiment, the diameter D of all the dimples 24 is the same dimension, and the depth H of all the dimples 24 is the same dimension.

  An example of a method of arranging a plurality of dimples 24 on the inner peripheral surface 22s of the ring portion 22 will be described. In the following, as shown in FIG. 3, on the inner peripheral surface 22s, a plurality of annular rows L in which dimples 24 are regularly scattered over the entire circumference in the circumferential direction are provided in a plurality of stages in the air flow direction ( The case of arrangement L1, L2, L3... Will be described as an example. Further, the critical Reynolds number Re when the flow state transitions from laminar flow to turbulent flow is set to 5000, the ratio (H / D) of the depth H to the diameter D of each dimple 24 is set to 0.2, and The diameter D of the dimple 24 is set to 1/100 of the fan diameter.

  First, when determining the arrangement of the alignment L1, a cross section parallel to the direction orthogonal to the rotation axis A is set on the inner peripheral surface 22s of the suction portion 22a of the ring portion 22. Next, the positions of the dimples 24 are determined, for example, at intervals of 2 ° on a concentric circle (on the circle passing through the inner peripheral surface 22s) centering on the rotation axis A in this cross section.

  Next, when determining the arrangement of the line L2, a cross section different from the above is set at a position shifted to the downstream side (blow-out side) of the air flow from the line L1. In this cross section, the positions of the dimples 24 are determined at intervals of 2 ° on concentric circles centering on the rotation axis A (on a circle passing through the inner peripheral surface 22s) in the same manner as the arrangement L1. At this time, as shown in FIG. 3, the dimples 24 in the row L2 are arranged at positions shifted by 1 ° in the circumferential direction with respect to the dimples 24 in the row L1. Hereinafter, the arrangement L after the arrangement L3 is similarly determined. Note that the arrangement method of the plurality of dimples 24 is not limited to the above-described method, and other methods may be employed.

  FIG. 6A is a schematic diagram showing the air flow in the axial blower 10 according to the present embodiment, and FIG. 6B is a schematic diagram showing the air flow in the axial blower in which no dimples are provided. FIG. The axial blower of the reference example shown in FIG. 6 (B) has the same configuration as the axial blower 10 according to the present embodiment except that no dimple is provided in the ring portion.

  In the axial blower 10 shown in FIG. 6A and the axial blower of the reference example shown in FIG. 6B, air flows backward in the gap (chip clearance) between the ring portion 22 and the partition portion 30a of the bell mouth 30. The phenomenon occurs. The reverse flow BF flows in a direction opposite to the direction of the main flow MF passing through the inside of the ring portion 22.

  In the axial blower of the reference example shown in FIG. 6 (B), when the backflow BF as described above occurs, the main flow MF passes through the impeller 20 while entraining the backflow BF, so that the tip of the suction portion 22a in the ring portion 22 Large peeling S2 occurs in the portion and the vicinity thereof. In addition, since this axial blower is a semi-open type, the main flow MF is easy to entrain the back flow BF, and peeling is likely to occur at the tip of the suction portion in the ring portion 22. In addition, in the impeller 20 having the ring portion 22, the flow near the rotation axis A becomes dominant, so that the flow separated on the inner peripheral surface of the suction portion is less likely to reattach to the inner peripheral surface of the ring portion 22.

  On the other hand, in the axial blower 10 according to the present embodiment shown in FIG. 6A, a plurality of concave dimples 24 arranged in the circumferential direction are provided on the inner peripheral surface 22 s of the ring portion 22. Since these dimples 24 cause turbulent flow in the air flowing in the vicinity thereof, the mixing of the air flowing in the vicinity of the dimple 24 and the surrounding air is promoted. Thereby, the air peeled off at the tip of the suction portion 22a of the ring portion 22 is likely to flow along the vicinity of the inner peripheral surface 22s of the suction portion 22a, and is easily reattached to the inner peripheral surface 22s of the suction portion 22a. . Therefore, separation of air sucked into the impeller 20 is suppressed, and fan performance can be improved.

  FIGS. 7 to 9 show the characteristics of the axial fan 10 shown in FIG. 6A according to the present embodiment and the characteristics of the axial fan of the reference example shown in FIG. 6B where no dimple is provided. It is a graph which shows the result of comparison. In the graph of FIG. 7, the horizontal axis represents the flow coefficient, and the vertical axis represents the static pressure coefficient. In the graph of FIG. 8, the horizontal axis indicates the flow coefficient, and the vertical axis indicates the specific noise. In the graph of FIG. 9, the horizontal axis indicates the flow coefficient, and the vertical axis indicates the total pressure efficiency.

  As can be seen from FIG. 7, the axial flow fan 10 of the present embodiment having the dimples 24 has a higher static pressure coefficient as a whole than the axial flow fan of the reference example having no dimples. In particular, in the region where the flow rate is large (the region on the right side of the graph of FIG. 7), the difference in the static pressure coefficient is larger, and the effect of the dimple 24 appears more significantly.

  Further, as can be seen from FIG. 8, the axial flow fan 10 of the present embodiment has a lower specific noise overall than the axial flow blower of the reference example. In particular, in the region where the flow rate is large (the region on the right side of the graph of FIG. 8), the degree of reduction in specific noise is greater, and the effect of the dimple 24 appears more prominently.

  Further, as can be seen from FIG. 9, the axial blower 10 of the present embodiment has a high total pressure efficiency as a whole compared to the axial blower of the reference example. In particular, in the region where the flow rate is large (the region on the right side of the graph of FIG. 9), the difference in total pressure efficiency is larger, and the effect of the dimple 24 appears more prominently.

  In addition, the definition of the term regarding the data of the said graph is as follows.

Flow coefficient Φ = (Q / 60) / (A · Ut)
Static pressure coefficient ψ = Ps / {(γ / 2g) · Ut ² }
Total pressure coefficient ηt = {Q (Ps + Pt)} / 6120 · L
Specific noise K _SA [dB] = SPL _A -10 log ₁₀ {(Q · Ps) / 60} ^2.5
Shaft power L [kW] = (TN) / 974
Q: Air volume (m ³ / min)
A: Annular flow area (m ² )
Ut: Blade tip peripheral speed (m / s)
γ: Specific weight of air (kgf / m ³ )
Ps: Static pressure (mmAq)
Pt: Total pressure (mmAq)
SPL _A : Noise level (dB)
T: Torque (kgf · m)
N: Fan speed (rpm)
g: Gravity acceleration

  As described above, in the present embodiment, peeling is suppressed by providing a plurality of dimples 24 arranged in the circumferential direction on the inner peripheral surface 22s of the suction portion 22a located in the suction side region of the ring portion 22, Fan performance can be improved. That is, the separation of the air is suppressed by causing the plurality of dimples 24 to transition the air flowing in a laminar flow state into a turbulent flow state at the tip end of the suction portion 22a of the ring portion 22. Specifically, it is as follows.

  Since the plurality of dimples 24 cause turbulent flow in the air flowing in the vicinity thereof, the mixing of the air flowing in the vicinity of the dimple 24 and the surrounding air is promoted. Thereby, the air peeled off at the tip of the suction portion 22a of the ring portion 22 is likely to flow along the vicinity of the inner peripheral surface 22s of the suction portion 22a, and is easily reattached to the inner peripheral surface 22s of the suction portion 22a. . Therefore, separation of air sucked into the impeller 20 is suppressed, and fan performance can be improved.

  In the present embodiment, the plurality of dimples 24 are arranged on the condition that the diameter D of each dimple 24 is larger than the distance G between adjacent dimples 24. As described above, the plurality of dimples 24 are arranged relatively densely on the inner peripheral surface 22s of the suction portion 22a, whereby the effect of suppressing peeling can be further enhanced.

  In the present embodiment, each dimple 24 has a concave shape that curves smoothly. As described above, since the shapes of the plurality of dimples 24 are aligned in a concave shape, it is possible to obtain a peeling suppression effect with little variation in the circumferential direction on the inner peripheral surface 22s of the suction portion 22a.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to each said embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning.

  For example, in the above-described embodiment, the case where the dimple 24 is provided on the inner peripheral surface 22s of the suction portion 22a of the ring portion 22 and is not provided on the blowout portion 22b is illustrated, but the present invention is not limited thereto. For example, as shown in FIG. 10, the dimple 24 can be provided not only on the inner peripheral surface 22s of the suction portion 22a but also on the inner peripheral surface of the blowing portion 22b. Thereby, peeling is suppressed also in the internal peripheral surface of the blowing part 22b.

  In the embodiment, the case where the diameter D and the depth H of the plurality of dimples 24 are set to the same dimension is illustrated, but the present invention is not limited to this. For example, a region where the diameter D of the dimple 24 gradually increases or gradually decreases toward the downstream side (blow-out side) of the air flow may be provided. Similarly, a region where the depth H of the dimple 24 gradually increases or gradually decreases as it goes downstream of the air flow may be provided.

  In the embodiment, the case where the diameter D of each dimple 24 is larger than the distance G between the adjacent dimples 24 is exemplified, but the present invention is not limited to this.

  In the above-described embodiment, the case where each dimple 24 has a concave shape that is smoothly curved (a concave shape such as a part of a spherical surface) is illustrated, but the present invention is not limited to this. For example, each dimple 24 may have a concave shape such as a part of a polyhedron.

  In the said embodiment, although the case where the axial-flow fan 10 was a semi-open type was illustrated, it is not limited to this.

  In the above embodiment, the example in which the axial blower of the present invention is applied to an air conditioner has been described, but the present invention is a refrigeration apparatus other than an air conditioner, such as a refrigerator, a refrigerator, a heat pump water heater, It can also be applied to ventilation equipment.

DESCRIPTION OF SYMBOLS 10 Axial fan 20 Impeller 21 Blade 22 Ring part 22a Suction part 22b Outlet part 23 Hub 24 Dimple 30 Bell mouth 30a Partition part D Dimple diameter G (G1, G2, G3) Distance between adjacent dimples H Dimple depth The

Claims (5)

A plurality of blades (21) provided around the rotation axis (A), and a ring portion (1) provided integrally with the plurality of blades (21) along the outer peripheral edge of the plurality of blades (21) 22) and an impeller (20),
A partition portion (30a) that is arranged with a predetermined gap from the ring portion (22) so as to surround the outer periphery of the ring portion (22), and divides an air flow path;
An axial blower in which a plurality of dimples (24) arranged in the circumferential direction are provided on the inner peripheral surface (22s) of the suction side region (22a) of the ring portion (22).   The axial blower according to claim 1, wherein the suction side region (22a) has a flare shape.   The axial flow fan according to claim 1 or 2, wherein a diameter (D) of each dimple (24) is larger than a distance (G) between adjacent dimples (24).   The axial flow blower according to any one of claims 1 to 3, wherein each dimple (24) has a concave shape that is smoothly curved.   An air conditioner using the axial blower according to any one of claims 1 to 4 as a blower for an outdoor unit.

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