Fan, air conditioning system, outdoor unit thereof, and refrigeration cycle device

Abstract

A fan 11 is provided. The fan (11) comprises a rotating body (propeller) 20 having: a hub 21 that rotates about a rotation axis; and a plurality of blades 22, each of which is a forward-swept blade connected to the hub 20. Each of the plurality of blades 22 has a leading edge 23 configured to include a blade-root-side section 31 substantially having a first inclination A, an intermediate section 32 substantially having a second inclination B, and a blade-tip-side section 33 substantially having a third inclination C from the blade root 25 toward the blade tip 26 on a meridian plane of the blade 22. The first inclination A of the blade-root-side section 31, the second inclination B of the intermediate section 32, and the third inclination C of the blade-tip-side section 33 satisfy the relationships B > 0, A > B, and C > B.

Description

Fans, air conditioning systems, their outdoor units, and refrigeration cycle devices

[0001] This disclosure relates to a fan, an air conditioning system and its outdoor unit, and more particularly to a fan having forward-swept blades, an air conditioning system having a fan, an outdoor unit of an air conditioning system, and a refrigeration cycle device having a fan.

[0002] Traditionally, Annual Performance Factor (APF) has been a key indicator for air conditioners, and continuous improvement in APF is required. Optimizing the outdoor unit's configuration is crucial for improving APF. The structure of an air conditioner's outdoor unit typically includes a propeller within the casing and a bell mouth surrounding the propeller that defines the discharge outlet. Improving the configuration of these components is believed to contribute to improving the overall efficiency of the air conditioner. In particular, developing a highly efficient propeller fan for outdoor units is expected to significantly contribute to energy conservation in air conditioners.

[0003] Conventionally, regarding the shape of a propeller, an axial flow blade that achieves high efficiency by incorporating a "forward-swept wing" that moves the blade forward in the direction of rotation is known (Patent Document 1: Japanese Unexamined Patent Publication No. 61-65096). Many current propeller fans are designed based on this "forward-swept wing" concept.

[0004] Furthermore, propeller fans employing forward-swept wings designed to mimic the shape of a delta wing at the leading edge of the wingtip are also known. This makes the strength of the two vortices rising from the wingtip and leading edge roughly equal, thereby suppressing the decrease in efficiency caused by the difference in the strength of the two vortices (Patent Document 2: Japanese Patent Application Publication No. 2001-227498).

[0005] Furthermore, wingtip vortices rising from the wingtips play an important role in propeller fans, and axial flow fans with curved sections at the wingtips are known to control the trajectory of wingtip vortices in forward-swept wings (Patent Document 3: Japanese Patent No. 3912418).

[0006] Furthermore, Patent Document 4 (International Publication No. 2020 / 136750) discloses an impeller, blower, and air conditioner employing forward-swept blades, and more specifically, discloses a configuration that suppresses the collapse of wingtip vortices by forming the leading edge of the blade such that the intake side is concave between the radial middle portion and the outer peripheral edge.

[0007] Furthermore, Patent Document 5 (Japanese Patent Publication No. 2003-148395) discloses an air conditioning fan impeller that also employs forward-swept blades, and more specifically, discloses an impeller in which the radial cross-sectional shape of the blade is configured such that the radius of curvature of the curve, which is concave towards the windward side on the outer circumference from E-E, increases from the leading edge to the trailing edge of the blade. This shape suppresses the increase in losses due to wingtip vortices.

[0008] Japanese Unexamined Patent Publication No. 61-65096, Japanese Unexamined Patent Publication No. 2001-227498, Japanese Patent No. 3912418, International Publication No. 2020 / 136750, Japanese Unexamined Patent Publication No. 2003-148395

[0009] While the adoption of forward-swept wings is a prerequisite for increasing the efficiency of propeller fans, forward-swept wings present two main challenges. The first challenge is controlling the vortex structure at the leading edge of the wing, and the second challenge is controlling the wingtip vortices.

[0010] The prior art described in Patent Document 2 is effective in controlling the vortex structure at the leading edge of a wing. However, in forward-swept wings, vortex buildup from the leading edge is unavoidable. In addition to this vortex buildup from the leading edge, vortices are generated to counteract it. These two vortices cause flow separation at the leading edge, preventing the flow from smoothly entering the wing, and as a result, losses around the leading edge increase. Since vortex buildup from the leading edge is unavoidable when using forward-swept wings, the technology in Patent Document 2 has limitations in terms of achieving high efficiency.

[0011] Patent documents 3 and 4 disclose techniques effective in controlling wingtip vortices. However, neither of these prior arts considers the effect of wingtip vortices interfering with adjacent wings after passing between them.

[0012] Patent Document 5 does not disclose any technology relating to vortices rising from the leading edge of a wing or vortices that counteract them. In the prior art described in Patent Document 5, the inclination near the middle of the leading edge of the wing is zero or nearly zero, so the boundary layer thickens in this area due to centrifugal force, which may result in increased losses near the leading edge.

[0013] This disclosure has been made in view of the above points, and aims to provide a highly efficient fan, an air conditioning system equipped with a fan, an outdoor unit of an air conditioning system, and a refrigeration cycle device equipped with a fan, by suppressing the generation of vortices rising from the leading edge of the blade and opposing vortices, and by reducing losses around the leading edge.

[0014] In accordance with this disclosure, a fan having the following features is provided to solve the above problems. The fan comprises a rotating body having a hub that rotates around a rotation axis and a plurality of blades, each of which is a forward-swept blade, coupled to the hub. In this fan, each of the plurality of blades has a leading edge that, in the meridional plane of the blade, comprises a root-side section having a generally first inclination A from the root to the tip, an intermediate section having a generally second inclination B, and a tip-side section having a generally third inclination C. In this fan, the first inclination A of the root-side section, the second inclination B of the intermediate section, and the third inclination C of the tip-side section satisfy the relationships B > 0, A > B, and C > B.

[0015] In accordance with this disclosure, an air conditioning system, an outdoor unit of the air conditioning system, and a refrigeration cycle device are also provided, each comprising a fan having the above-described features.

[0016] With the above configuration, the slope in the middle of the leading edge is reduced, making it difficult for the flow to cross over to the negative pressure side. This suppresses the upward movement of vortices from the leading edge of the blade and the generation of counter-vortices, thereby reducing losses around the leading edge and ultimately enabling high fan efficiency and power saving for the equipment equipped with it.

[0017] Figure 1 is a schematic diagram of an air conditioning system that may include a fan according to an embodiment of the present disclosure. Figure 2 is a schematic diagram of an outdoor unit of an air conditioning system that includes a fan according to an embodiment of the present disclosure. Figure 3 is a diagram illustrating the vortex structure at the leading edge of a propeller of a conventional forward-swept blade fan. Figure 4 is a diagram illustrating the vortex structure at the leading edge of a propeller and losses around the blade of a conventional forward-swept blade fan propeller. Figure 5 is a diagram of the configuration of a propeller according to an embodiment of the present disclosure. Figure 6 shows the radial profiles of the leading and trailing edges of the blades in the meridional plane of the propeller blades according to an embodiment of the present disclosure. Figure 7 is a perspective view of the propeller from the discharge side to illustrate the shape around the trailing edge of the propeller blades according to an embodiment of the present disclosure. Figure 8 is a schematic diagram illustrating the arrangement of the propeller within the bell mouth in a fan according to an embodiment of the present disclosure. Figure 9 is a diagram illustrating the shape of a baseline propeller for comparison with the propeller according to an embodiment of the present disclosure. Figure 10 is a diagram illustrating a comparison of the analysis results of the propeller according to an embodiment of the present disclosure with a baseline propeller. Figure 11 illustrates the performance of a fan equipped with a propeller according to an embodiment of the present disclosure, compared to that of a baseline propeller. Figure 12 illustrates the change in the position of the vortex center of the blade tip vortex on the blade radius at the trailing edge of the propeller according to an embodiment of the present disclosure, compared to a baseline propeller. Figure 13 illustrates the reason why the total pressure loss around the blade is reduced in the propeller according to an embodiment of the present disclosure compared to a baseline propeller. Figure 14 is a schematic diagram of the outdoor unit of an air conditioning system equipped with a fan according to another embodiment of the present disclosure.

[0018] The embodiments of this disclosure will be described below with reference to the drawings, but the embodiments of this disclosure are not limited to the specific embodiments described below. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0019] This disclosure covers a fan with forward-swept blades, an air conditioning system with a fan, an outdoor unit thereof, and a refrigeration cycle device with a fan.

[0020] A fan according to an embodiment of the present disclosure comprises a rotating body (propeller) having a hub that rotates around a rotation axis and a plurality of blades, each of which is a forward-swept blade, connected to the hub. In this configuration, each of the plurality of blades has a leading edge that, in the meridional plane of the blade, comprises a root-side section having a generally first inclination A from the root to the tip, an intermediate section having a generally second inclination B, and a tip-side section having a generally third inclination C. In this configuration, the first inclination A of the root-side section, the second inclination B of the intermediate section, and the third inclination C of the tip-side section satisfy the relationships B > 0, A > B, and C > B.

[0021] With the above configuration, the slope in the middle of the wing's leading edge is reduced, making it difficult for the flow to cross over to the negative pressure side. This suppresses the generation of vortices rising from the wing's leading edge and counteracting vortices, thereby reducing losses around the leading edge. In turn, it becomes possible to achieve high efficiency in the fan and power savings in the equipment that incorporates it.

[0022] In a preferred embodiment, the first inclination A of the wing root section is in the range of 25 degrees < A < 45 degrees. The second inclination B of the intermediate section is in the range of 5 degrees < B < 15 degrees. The third inclination C of the wing tip section is in the range of 25 degrees < C < 45 degrees. This optimizes the efficiency of the fan and the power consumption of the device equipped with the fan.

[0023] In a preferred embodiment, each of the multiple blades has a trailing edge. The trailing edge is configured to be convex towards the fan discharge side at a predetermined distance from the trailing edge toward the leading edge between the midpoint of the trailing edge and the blade tip. This allows the position of the blade tip vortex to be moved radially inward, reducing the interaction between the blade tip vortex and the bell mouth wall, and reducing the loss in the clearance between the blade tip and the bell mouth caused by the blade tip vortex.

[0024] In a preferred embodiment, the fan further includes a bell mouth having a cylindrical portion. The intermediate section of the leading edge coincides with the inlet of the bell mouth, or the intermediate section of the leading edge is located inside the inlet of the bell mouth. This allows the flow to be accelerated by the bell mouth, further suppressing the vortex rising from the leading edge.

[0025] In a preferred embodiment, the fan further includes a bell mouth having a cylindrical portion. The entire trailing edge is located within the cylindrical portion of the bell mouth. While tip vortices tend to spread radially outward due to centrifugal force, positioning the trailing edge of the wingtip inside the cylindrical portion of the bell mouth keeps the tip vortices within the bell mouth's cylindrical portion, suppressing their radial outward spread. As a result, the tip vortices are more likely to move radially inward.

[0026] In certain embodiments, the average slope of the leading edge from the wing root to the wingtip is in the range of 20 to 40 degrees (including both endpoints). In certain embodiments, the intermediate section is in the range of 20% to 80% radius, where the radius of the wing root is defined as 0% and the radius of the wingtip as 100%, and the width of the intermediate section is at least 20%. In more specific embodiments, the wing root section, intermediate section, and wingtip section are sections obtained by dividing the wing from the wing root to the wingtip into approximately three equal parts in the radial direction. In certain embodiments, there is a first transition between the wing root section and the intermediate section, where the slope changes from a first slope A to a second slope B. In certain embodiments, there is a second transition between the intermediate section and the wingtip section, where the slope changes from a second slope B to a third slope C.

[0027] In certain embodiments, each of the plurality of wings has a trailing edge that is positioned on the exhaust side of the height of the leading edge in the meridional plane over the range from the wing root to the wingtip. The trailing edge is composed of a first section having a negative slope and a second section having a positive slope in the meridional plane from the wing root to the wingtip.

[0028] The outdoor unit of the air conditioning system provided in this disclosure comprises the fan described above and an outdoor heat exchanger through which the air blown by the fan passes.

[0029] The air conditioning system according to this disclosure includes the above-mentioned outdoor unit and one or more indoor units connected to the outdoor unit via refrigerant piping.

[0030] The refrigeration cycle device according to this disclosure includes the fan described above.

[0031] In this specification, regarding a certain section in the meridian plane of the wing, "having a generally inclination of X [degrees]" means that the local inclination angle y at all points in that section has an inclination within the range of ±5% of the inclination of X [degrees] (0.95X < y < 1.05X). It should be noted that "the inclination X is greater than zero (X > 0)" means that in the section within the range of ±5% of the inclination X in the above definition, the local inclination angle y is always positive (that is, min y > 0).

[0032] Hereinafter, referring to FIGS. 1 to 8, as an example of a fan, an air conditioning system, and its outdoor unit according to an embodiment of the present disclosure, a fan 11 having a propeller 20, an air conditioning system 1 including the fan 11, and its outdoor unit 10 will be described as examples.

[0033] Referring to FIG. 1, a schematic configuration of an air conditioning system 1 that may include a fan 11 according to an embodiment of the present disclosure will be described. The air conditioning system 1 is a device that performs air conditioning by circulating a refrigerant in a refrigeration cycle. As shown in FIG. 1, the air conditioning system 1 includes one or more indoor units 4 (4a, 4b...) installed indoors (in the air-conditioned space) and an outdoor unit 10 installed outdoors. The one or more indoor units 4a, 4b... and the outdoor unit 10 are connected via a refrigerant pipe 2. As the refrigerant, for example, hydrofluorocarbons such as R410a and R32 can be used.

[0034] The indoor unit 4 takes in indoor air during operation, exchanges heat between the taken-in air and the refrigerant supplied from the outdoor unit 10, blows out the cooled air or the warmed air, and cools or warms the indoor space to a set temperature. The indoor unit 4 includes an indoor heat exchanger and an indoor fan such as a centrifugal fan in the refrigeration cycle of the air conditioning system 1.

[0035] The outdoor unit 10 starts up upon receiving a designation from a control device, controls the operation of a compressor and an outdoor fan according to the operation mode set by an operation device, and such operation devices include a remote controller, a centralized control device, and the like.

[0036] In addition, in FIG. 1, two indoor units 4a and 4b are shown as the indoor unit 4. However, the number of indoor units 4 is not particularly limited, and it may be one or three or more. Also, although one outdoor unit 10 is illustrated, the number of outdoor units 10 is not limited to one.

[0037] In the air conditioning system 1, the indoor unit 4 and the outdoor unit 10 are connected via a communication line not shown. In addition, an operating device such as a remote controller for operating the indoor unit 4 via a communication line may be connected to the room where the indoor unit 4 is installed. Further, a centralized controller for centrally controlling one or more indoor units 4a, 4b and the outdoor unit 10 may be connected via a communication line.

[0038] In the example shown in FIG. 1, the air conditioning system 1 depicts an embodiment of a multi-air conditioner for a building including an upward blowing type outdoor unit 10 as an example. The fan according to the embodiment of the present disclosure can be suitably applied to an upward blowing type outdoor unit. However, in the embodiment of the present disclosure, the form of the air conditioning system 1 is not necessarily limited to this, and it may be targeted at a package air conditioner.

[0039] Next, referring to FIG. 2, the schematic configuration of the outdoor unit 10 of the air conditioning system 1 including the fan 11 according to the embodiment of the present disclosure will be described.

[0040] The outdoor unit 10 includes, in the refrigeration cycle, a fan 11, a compressor 16, an outdoor heat exchanger 17, a four-way valve not shown, and an expansion valve. [[ID=[]]

[0041] The outdoor unit 10 shown in FIG. 2 includes a compressor 16 disposed in a housing 19, an outdoor heat exchanger 17, an electrical component box 18 disposed above the compressor 16, a stay 14 to which the electrical component box 18 is attached, and a fan 11 fixed to the stay 14. A bellmouth 15 covering the housing 19 is provided on the outer periphery of the fan 11. In the embodiment to be described, the bellmouth 15 is integrated with a shroud. A fan guard 12 is provided at the outlet of the bellmouth 15.

[0042] The fan 11 comprises the bell mouth 15 described above, a propeller 20 as a rotating body, and a motor 13 that drives the propeller 20. The propeller 20 has blades that cause the wind to flow while swirling along the axis of rotation, and the number of blades is not particularly limited, but for example it is composed of three blades. The outdoor unit 10 draws in air from outside the housing through the side of the outdoor heat exchanger 17 as the propeller 20 of the fan 11 is rotated by the motor 13, as shown by the thick arrow in Figure 2, performs heat exchange in the outdoor heat exchanger 17, and discharges the air into the atmosphere from the upper opening of the bell mouth 15.

[0043] The fan 11 according to the embodiments of this disclosure is configured to blow or draw in air by rotating a propeller 20 with a motor 13. The outdoor unit 10 of the air conditioning system is not particularly limited as long as it is equipped with the propeller 20 of the fan 11.

[0044] In the air conditioning system 1 described above, improving the efficiency of the fan for the outdoor unit 10 is expected to greatly contribute to energy saving. While the adoption of forward-swept blades is a prerequisite for improving fan efficiency, forward-swept blades present two main challenges: one is controlling the vortex structure generated at the leading edge of the blade, and the other is controlling the tip vortices generated at the blade tips (or outer edges).

[0045] In forward-swept wings, vortex buildup from the leading edge is unavoidable. Referring to Figures 3 and 4, the vortex structure at the leading edge of a propeller in a conventional fan employing a forward-swept wing is explained. Figures 3 and 4 were obtained through analysis using commercially available fluid dynamics software. Figure 3(A) shows the streamline diagram of the negative pressure surface of a conventional wing, along with the positions of the separation line and reattachment line. Figure 3(B) shows the streamline diagram of the pressure surface of a conventional wing, along with the position of the reattachment line. Figure 3(C) illustrates the vortex S rising from the leading edge of a conventional wing and the corresponding vortex T. The streamlines shown in the streamline diagrams used in Figures 3(A) and (B) are what are called critical streamlines. Critical streamlines are lines that represent the direction of flow drawn on a wall surface. More specifically, critical streamlines are drawn by topological analysis of friction stress lines on a wall surface based on singularity theory. From the degenerate two-dimensional information on the wall surface, known as critical streamlines, a three-dimensional vortex structure on the wall surface can be extracted. The areas where streamlines converge or separate are called "envelopes." These envelopes correspond to flow separation lines or adhesion lines. The same principle applies to the streamline diagrams shown in Figures 10 and 12.

[0046] As shown in Figure 3(C), in addition to the vortex S rising from the leading edge of the wing, a further vortex T is generated to counteract it. Due to these two vortices S and T, the flow at the leading edge of the wing separates, as indicated by the separation line in Figure 3(A), preventing the flow from smoothly entering the wing, and as a result, losses around the leading edge increase.

[0047] Figure 4 illustrates the vortex structure at the leading edge of a fan propeller and the losses around the wing that occur in conventional forward-swept wings. Figure 4(A) shows a conventional wing with a vortex S rising from the leading edge, and correspondingly generated vortices T and wingtip vortices U. Figure 4(A) visualizes the vortex centers of vortices S, T, and wingtip vortices U using a vortex center identification method based on singularity theory, colored with helicity and then converted to grayscale. Figure 4(B) shows the total pressure loss around a conventional wing using forward-swept wings. Figure 4(B) visualizes the distribution of the total pressure loss coefficient, suggesting a region with a relatively high total pressure loss coefficient. As shown in Figure 4(B), in the conventional technology, a region with a high total pressure loss coefficient is created due to the complex vortex structure around the leading edge of the wing. Furthermore, the shape of the leading edge affects vortices S and T.

[0048] Since forward-swept wings inevitably generate vortices rising from the leading edge, it is expected that by designing the shape of the leading edge, the generation of vortices S rising from the leading edge and opposing vortices T will be suppressed, reducing losses around the leading edge and improving the efficiency of the fan.

[0049] Therefore, in this embodiment, the fan is equipped with a propeller having a hub that rotates around a rotation axis and a plurality of forward-moving blades connected to the hub. Each of the plurality of blades has a leading edge that, in the meridional plane of the blade, includes a root-side section having a generally first inclination A from the root to the tip, an intermediate section having a generally second inclination B, and an tip-side section having a generally third inclination C. The first inclination A of the root-side section, the second inclination B of the intermediate section, and the third inclination C of the tip-side section satisfy the relationships B>0, A>B, and C>B. This reduces the intermediate inclination of the leading edge, making it difficult for the flow to cross over to the negative pressure side, suppressing the winding up of vortices S from the leading edge of the blade and the generation of opposing vortices T, thereby reducing losses around the leading edge.

[0050] Figure 5 shows the configuration of the propeller 20 provided in the fan 11 according to an embodiment of the present disclosure. Figure 5(A) is a top view showing the propeller 20 in the fan 11 together with the inner diameter of the cylindrical portion of the bell mouth 15. Figure 5(B) is a perspective view of the propeller 20 in the fan 11.

[0051] As shown in Figure 5, the propeller 20 is attached to the shaft of the motor 13 shown in Figure 2 and comprises a hub 21 that rotates around the axis of rotation and a plurality of blades 22 (22-1 to 22-3) coupled to the hub 21. In the embodiment described, the propeller 20 is described as having three blades 22-1 to 22-3, but the number of blades is not particularly limited to this. Each blade 22 has a leading edge 23, a trailing edge 24, a blade root 25, and a blade tip (or outer edge) 26.

[0052] Figure 5(A) also shows the inner diameter 15a of the cylindrical part of the bell mouth 15, and a predetermined clearance is left between the wingtip 26 and the inner diameter 15a of the cylindrical part. The direction of rotation of the propeller 20 is indicated by the bold arrow R. As shown in Figure 5(A), the wing 22 is a "forward-swept wing" that advances the wing in the rotation direction R.

[0053] Referring to Figure 5(A), when the propeller 20 is characterized in a plane (a plane perpendicular to the axis of rotation), in the embodiment shown in Figure 5(A), the central angle θ of the fan from the leading edge to the trailing edge defined by the wingtip 26 of one wing 22 Ｃ The angle is not particularly limited, but is between 70 and 110 degrees. The central angle θ of the sector defined by the wing root 25 instead of the wingtip 26. ｃＨ The ranges are roughly the same.

[0054] A characteristic of a "forward-swept wing" is that the wingtip side edge advances at an angle (forward-swept angle θ) relative to the wing root side edge of the leading edge 23. Ｌ ) and the angle at which the wingtip side edge advances relative to the wing root side edge of the trailing edge 24 (advance angle θ) Ｔ The angles are not particularly limited, but are in the range of 20 to 55 degrees, respectively. The advance angle θ of the leading edge 23 Ｌ and the advance angle θ of the trailing edge 24 ＴIt is determined according to the design specifications. In the example shown in FIG. 5, the advance angle θ of the trailing edge 24 Ｔ is larger than the advance angle θ of the leading edge 23 Ｌ . Also, regarding the advance angle defined at the intermediate point M between the tip 26 and the root 25 in the radial direction instead of the tip side end portion, the advance angle θ for the leading edge 23 Ｌ ’ is in the range of 5 degrees to 15 degrees, and the advance angle θ for the trailing edge Ｔ ’ is in the range of 20 degrees to 30 degrees.

[0055] Referring to FIG. 5(B), when the propeller 20 is characterized in the height direction (the direction along the rotation axis), the root 25 of the blade 22-1 has a shape that obliquely crosses the cylindrical surface of the hub 21. The blade 22 has a shape inclined from the leading edge 23 toward the trailing edge 24. The trailing edge 24 is disposed on the discharge side higher than the height of the leading edge 23 over the range from the root 25 to the tip 26 of the blade.

[0056] Hereinafter, referring to FIG. 6, the characteristics of the propeller 20 will be described more specifically. FIG. 6 shows the radial profiles of the leading edge 23 and the trailing edge 24 of the blade 22 of the propeller 20 included in the fan 11 according to the embodiment of the present disclosure in the meridian plane of the blade. Here, the meridian plane refers to a view obtained by rotationally projecting the leading edge 23 and the trailing edge 24 onto a cross-section passing through the rotation axis. The vertical axis is the height with the height at the root 25 of the trailing edge 24 as the reference zero, and the horizontal axis is the position in the blade radius direction.

[0057] As shown in FIG. 6, the leading edge 23 of the blade 22 includes, in the meridian plane, a root side section 31 having a generally first inclination A from the root 25 toward the tip 26, an intermediate section 32 having a generally second inclination B, and a tip side section 33 having a generally third inclination C. The first inclination A of the root side section, the second inclination B of the intermediate section 32, and the third inclination C of the tip side section 33 preferably satisfy the relationship of B>0, A>B, and C>B.

[0058] In a preferred embodiment, the first inclination A of the wing root section 31 is in the range of 25 degrees < A < 45 degrees, the second inclination B of the intermediate section 32 is in the range of 5 degrees < B < 15 degrees, and the third inclination C of the wingtip section 33 is in the range of 25 degrees < C < 45 degrees. Here, if the radius of the wing root 25 is defined as 0% and the radius of the wingtip 26 is defined as 100%, the intermediate section 32 is in the range of 20% to 80% radius, and it is desirable that its width be at least 20%. In the embodiment described, the wing root section 31, the intermediate section 32, and the wingtip section 33 are sections that divide the wing from the wing root 25 to the wingtip 26 radially into approximately three equal parts (that is, the intermediate section 32 is in the range of approximately 33% to 67% radius, and its width is approximately 33%), but the way the sections are divided is not limited as long as three or more sections with different inclinations can be defined. As described above, "having approximately an inclination of X [degrees]" in a certain section of the meridional plane of the wing 22 means that the local inclination angle y at all points in that section is within the range of ±5% of the inclination X [degrees] (0.95X < y < 1.05X). Furthermore, "inclination X is greater than zero (X > 0)" means that in the section within the range of ±5% of the inclination X in the above definition, the local inclination angle y is positive everywhere (i.e., min y > 0).

[0059] Furthermore, in the embodiment described, the average inclination of the section 30 of the leading edge 23 from the wing root 25 to the wingtip 26 is in the range of 20 to 40 degrees (including both endpoints).

[0060] In Figure 6, the inclination is discontinuous at the boundaries of the wing root section 31, the intermediate section 32, and the wingtip section 33, but there may be smoothed regions between each section where the inclination changes gradually. More specifically, there may be a first transition section 34 between the root section 31 and the intermediate section 32 where the inclination smoothly changes from a first inclination A to a second inclination B. There may be a second transition section 35 between the intermediate section 32 and the wingtip section 33 where the inclination smoothly changes from a second inclination B to a third inclination C.

[0061] By adopting the radial profile of the leading edge 23 in the meridional plane of the blade 22 described above, the inclination of the intermediate section 32 of the leading edge 23 is reduced, making it difficult for the flow to cross over to the negative pressure side. This suppresses the generation of vortices S rising from the leading edge 23 of the blade 22 and opposing vortices T, thereby reducing losses around the leading edge 23.

[0062] The height of the leading edge 23 is equal to the height H at the wing root 25. Ｒ While the height of the wing root increases radially outward from the base, the height of the trailing edge 24 decreases radially outward from the height at the wing root 25 (which is zero), and then increases further radially outward. That is, the trailing edge 24 is composed of a wing root-side section 41 with a negative slope and a wingtip-side section 42 with a positive slope, extending in the meridional plane from the wing root 25 to the wingtip 26. In Figure 6, there is a discontinuity at the boundary between the wing root-side section 41 and the wingtip-side section 42, but a third transition section 43 that smoothly changes from a negative slope to a positive slope may be provided between the wing root-side section 41 and the wingtip-side section 42. Furthermore, the wing root-side section 41 and the wingtip-side section 42 correspond to one-third and two-thirds of the section obtained by roughly dividing the distance from the wing root 25 to the wingtip 26 radially into three equal parts, but the way the sections are divided is not limited as long as two or more sections with different slopes can be defined.

[0063] As explained with reference to Figure 5(B), the trailing edge 24 is configured to have a height lower than the leading edge 23 in the meridional plane, from the wing root 25 to the wingtip 26, as shown in Figure 6.

[0064] The shape around the trailing edge 24 of the blade 22 of the propeller 20 will be described in more detail below with reference to Figure 7. Figure 7 is a perspective view of the propeller 20 as seen from the exhaust side, illustrating the shape around the trailing edge 24 of the blade of the propeller 20 that is provided in the fan 11 according to the embodiment of this disclosure.

[0065] In the embodiment shown in Figure 7, the trailing edge 24 of the wing 22 is configured to be convex towards the discharge side of the fan 11 at a predetermined distance d from the trailing edge 24 toward the leading edge 23, between the midpoint M of the trailing edge 24 and the wingtip 26, as shown by the thick dashed line Q in Figure 7. Here, the predetermined distance d is preferably 0.1 to 5%, more preferably 0.5 to 2%, of the propeller outer diameter. This allows the position of the wingtip vortex U to be moved radially inward according to the Biot-Savart law, as will be described later.

[0066] Figure 8 is a schematic diagram illustrating the arrangement of a propeller 20 within a bell mouth 15 in a fan 11 according to an embodiment of the present disclosure. In the embodiment shown in Figure 8, the bell mouth 15 has a structure (also referred to as a multi-stage expanding structure or long bell mouth structure) consisting of a cylindrical portion 15b rising from the bell mouth inlet 15c and a portion 15d whose diameter gradually increases above the cylindrical portion 15b. In the embodiment shown in Figure 8, the propeller 20 is positioned such that the intermediate section 32 of its leading edge 23 coincides with the inlet 15c of the bell mouth 15. Alternatively, in other embodiments, the propeller 20 may be positioned such that the intermediate section 32 of its leading edge 23 is located inside the inlet 15C of the bell mouth 15. This allows the flow to be accelerated by the bell mouth 15, further suppressing the winding up of vortices S from the leading edge 23 of the blade 22.

[0067] Hereinafter, with reference to Figures 9 to 13, the characteristics of the propeller 20 of the fan 11 according to the embodiment of this disclosure, which was described with reference to Figures 5 to 8, will be explained in comparison with a baseline propeller.

[0068] First, we will describe the specific design parameters of the propeller 20 to be compared with the baseline propeller fan. In the meridional plane of the wing 22, the entire section 30 of the leading edge 23 was divided radially into three equal parts, forming sections 31 to 33. The inclination A of the wing root section 31 of the leading edge 23 was set to approximately 34 degrees, the inclination B of the middle section 32 was set to approximately 10 degrees, the inclination C of the wingtip section 33 was set to approximately 37 degrees, and the average inclination from the wing root 25 to the wingtip 26 was set to approximately 28 degrees. In the meridional plane of the wing 22, the entire section 40 of the trailing edge 24 was divided radially into three equal parts, with the first third forming section 41 and the last two-thirds forming section 42. The inclination of the wing root section 41 of the trailing edge 24 was set to approximately -13 degrees, and the inclination of the wingtip section 42 was set to +10 degrees. The central angle is the central angle θ of the sector defined by the wingtip 26 of one wing 22, from the leading edge 23 to the trailing edge 24. Ｃ This was set to approximately 92 degrees. The forward sweep angle θ defined at the wingtip side of the leading edge 23. Ｌ The forward sweep angle θ is set to approximately 36 degrees and is defined at the wingtip side edge of the trailing edge 24. Ｔ The angle was set to approximately 41 degrees. The distance d defining the convex shape of the trailing edge was set to 1% of the propeller outer diameter.

[0069] Next, the design parameters of a baseline propeller 50 for comparison with the present propeller 20 will be described. Figure 9 is a diagram illustrating the shape of a baseline propeller 50 for comparison with the propeller 20 provided in the fan 11 according to an embodiment of the present disclosure. Figure 9(A) shows the radial profiles of the leading edge 53 and trailing edge 54 of the blade 52 of the baseline propeller 50 in the meridional plane. Figure 9(B) is a top view of the baseline propeller 50. Figure 9(C) is a perspective view of the baseline propeller 50.

[0070] As shown in Figure 9(A), the leading edge 53 of the blade 52 of the baseline propeller 50 has a generally uniform inclination L in the meridional plane from the blade root 55 to the blade tip 56. The average inclination L is approximately 30 degrees. The other design parameters are the same as those of the propeller 20 according to the embodiment of this disclosure.

[0071] Hereinafter, with reference to Figure 10, the vortex structure and total pressure loss distribution generated in the propeller 20 of the fan 11 according to the embodiment of this disclosure and the baseline propeller 50 will be described. Figure 10 was obtained by analysis using commercially available fluid analysis software. Figure 10 is a diagram illustrating a comparison of the analysis results of the propeller 20 of the fan 11 according to the embodiment of this disclosure with the baseline propeller 50. Figures 10(A) and 10(B) show the vortex structure at the leading edge of the blade for the baseline propeller 50(A) and the propeller 20(B) according to the embodiment of this disclosure. Figures 10(A) and 10(B) visualize the vortex centers of the generated vortices, similar to Figure 4(A). Figures 10(C) and 10(D) show the streamlines on the negative pressure surface of the blade for the baseline propeller 50(C) and the propeller 20(D) according to the embodiment of this disclosure. Figures 10(E) and 10(F) show the total pressure losses around the blades for a baseline propeller 50(E) and a propeller 20(F) according to embodiments of the present disclosure.

[0072] As is clear from comparing Figures 10(A) and 10(B), the propeller 20 according to the embodiment of the present disclosure has a weaker vortex in the mid-radius region around the leading edge compared to the baseline propeller 50. Due to this weakening of the vortex, as is clear from comparing Figures 10(C) and 10(D), the separation line becomes shorter and the airflow at the leading edge becomes smoother. Furthermore, as is clear from comparing Figures 10(E) and 10(F), the loss in the mid-radius region around the leading edge is reduced due to the influence of the vortex behavior. In this way, by reducing the slope in the middle of the leading edge, it becomes more difficult for the flow to cross over to the negative pressure side, thereby suppressing the generation of vortices S rising from the leading edge of the blade and opposing vortices T, and reducing losses around the leading edge.

[0073] Figure 11 is a diagram illustrating the performance of a fan 11 equipped with a propeller 20 according to an embodiment of the present disclosure, in comparison with a fan equipped with a baseline propeller 50.

[0074] Figures 11(A) and 11(B) are graphs showing the calculated individual performance of a fan 11 equipped with a propeller 20 according to an embodiment of the present disclosure and a fan equipped with a baseline propeller 50. Figure 11(A) is a graph showing the static pressure rise with respect to the fan's flow rate, and Figure 11(B) is a graph showing the static pressure efficiency with respect to the fan's flow rate. The graphs in Figures 11(A) and 11(B) were obtained by analysis using commercially available fluid analysis software. As shown in Figures 11(A) and 11(B), it was confirmed that the individual performance of the fan equipped with the propeller 20 is improved compared to the fan equipped with the baseline propeller 50 under conditions where an equivalent static pressure rise can be obtained.

[0075] Figure 11(C) is a graph showing experimental results of fan power consumption against airflow for an outdoor unit 10 equipped with a propeller 20 according to an embodiment of the present disclosure and an outdoor unit equipped with a baseline propeller 50. Figure 11(C) shows experimental results of fan power consumption against airflow, actually measured using an outdoor unit 10 fitted with a prototype of the propeller 20 and an outdoor unit fitted with a baseline propeller 50. As is clear from Figure 11(C), it was confirmed that power consumption was reduced at the same airflow. Thus, by optimizing the shape of the propeller, especially the profile of the leading edge, it is possible to achieve high efficiency for fans equipped with that propeller and power saving for air conditioning systems equipped with fans.

[0076] The following explanation, with reference to Figures 12 and 13, will describe why adopting the shape of the trailing edge 24 of the wing 22, as described with reference to Figure 7, allows the position of the wingtip vortex to be moved radially inward. Figures 12 and 13 were obtained by analysis using commercially available fluid analysis software.

[0077] Figure 12 illustrates the change in the position of the vortex center of the wingtip vortex of the propeller 20 of the fan 11 according to an embodiment of the present disclosure on the blade radius at the trailing edge 24 relative to the baseline propeller 50. Figures 12(A) and 12(B) show the wingtip vortex structure for the baseline propeller 50(A) and the propeller 20(B) of the fan 11 according to an embodiment of the present disclosure. Figures 12(A) and 12(B) visualize the vortex centers of the wingtip vortices, similar to Figure 4(A). Figures 12(C) and 12(D) show the streamlines of the pressure surface of the blade for the baseline propeller 50(C) and the propeller 20(D) of the fan 11 according to an embodiment of the present disclosure, along with the reattachment lines.

[0078] As is clear from comparing Figure 12(A) and Figure 12(B), the position (radius) of the vortex center U of the propeller 20 at the trailing edge 24 in this embodiment has shifted inward in the wing radial direction compared to the baseline propeller 50. The radius of the vortex center U of the propeller 20 at the trailing edge 24 in this embodiment has shifted inward by 1.7% (based on the baseline propeller 50's radius being 100%) compared to the baseline propeller 50. The reattachment line has also shifted inward in the wing radial direction. Thus, by adopting the shape of the trailing edge 24 of the wing 22 as described with reference to Figure 7, the interaction between the wingtip vortex and the wall of the bell mouth 15 is reduced, and losses are reduced.

[0079] Figure 12(E) is a schematic diagram of the wingtip vortex structure along the line A-A shown in Figure 12(D). Figure 12(F) is a diagram illustrating the Biot-Savart law, which explains the change in the radial position of the vortex center of the wingtip vortex. When the Biot-Savart law is applied to the relationship between the wingtip vortex and the pressure surface of the wing, the wingtip vortex is guided radially inward by the wall of the pressure surface. This guided velocity is given by Γ as the circulation and X as the distance between the wall and the vortex center. １ Therefore, Γ / (4π*X １ It is expressed as follows: Therefore, the induced velocity is X １ This will be inversely proportional. As shown in Figure 7, by making the shape convex on the exhaust side, the distance between the center of the wingtip vortex U and the wall becomes smaller, as shown in Figure 12(E) (X １(This decreases), the induction velocity increases, and the vortex center of the wingtip vortex is pulled inward in the direction of the wing radius.

[0080] Figure 13 illustrates the reason why the total pressure loss around the blade is reduced in the propeller 20 of the fan 11 according to the embodiment of the present disclosure compared to the baseline propeller 50. Figure 13(A) illustrates the tip vortex generated in the propeller, with the vortex center of the tip vortex U at the trailing edge represented by a sphere. Figure 13(B) illustrates the definition of the sphere representing the vortex center of the tip vortex U.

[0081] As shown in Figures 13(A) and (B), a sphere tangent to the pressure surface is defined with the position of the vortex center at the trailing edge of the visualized wingtip vortex as its center, and the radius of the sphere is measured as a distance, and the minimum distance X １ The minimum distance X of the propeller 20 according to the embodiment of this disclosure was determined. １ This represents an 18.4% reduction compared to the baseline propeller 50 (with the minimum distance of the baseline propeller 50 set as 100%).

[0082] Figures 13(C) to 13(F) show the total pressure loss around the blade for the baseline propeller 50 (C, D) and for the propeller 20 according to the embodiments of the present disclosure (E, F). As is clear from comparing Figure 13(C) and Figure 13(E), it was confirmed that the propeller 20 according to the embodiments of the present disclosure has reduced losses around the wingtip vortex due to the bell mouth effect compared to the baseline propeller 50.

[0083] As described above, according to the embodiments of this disclosure, it is possible to provide a highly efficient fan, an air conditioning system equipped with a fan, and an outdoor unit of an air conditioning system by suppressing the generation of vortices S rising from the leading edge of the blade and opposing vortices T, and by reducing losses around the leading edge.

[0084] Up to the above, an embodiment of a multi-split air conditioner for a building equipped with an upward-blowing type outdoor unit 10 has been described as a preferred embodiment. However, the fan according to the embodiment of this disclosure can also be applied to a side-blowing type outdoor unit 10B.

[0085] Figure 14 is a diagram illustrating the schematic configuration of an outdoor unit 10B of an air conditioning system 1 equipped with a fan according to another embodiment of the present disclosure. In the example shown in Figure 14, the air conditioning system 1 is depicted as an example of an embodiment of a horizontal-blowing type outdoor unit 10B. Figure 14(A) is a diagram illustrating the arrangement of the propeller 20B inside the bell mouth 15B. Figure 14(B) is a diagram showing the external appearance of the horizontal-blowing type outdoor unit 10B.

[0086] The horizontal-blowing type outdoor unit 10B is composed of two stages of fans 11B-1 and 11B-2, as shown in Figure 14(B). Figure 14(B) shows the state in which fan guards 12B-1 and 12B-2 are attached to each of the fans 11B-1 and 11B-2. The basic configuration of the outdoor unit 10B is the same as that of the outdoor unit 10 described with reference to Figure 2, so below we will explain the differences and omit the explanation of the common parts.

[0087] The fan 11B comprises a bell mouth 15B optimized for a side-blowing type, similar to the bell mouth 15 described above, and a propeller 20B as a rotating body. The propeller 20B has three blades 22-1 to 22-3, similar to the one shown in Figure 5.

[0088] In the configuration shown in Figure 14(A), the bell mouth 15B has a substantially cylindrical shape that rises from the bell mouth inlet 15c. The propeller having the configuration of this disclosure is also applicable to a horizontal-blowing type outdoor unit 10B as shown in Figure 14.

[0089] In the embodiments described above, an air conditioning system or air conditioner equipped with an outdoor unit having the fan described above was explained as an example. However, the fan according to this embodiment is not limited to a fan for an air conditioning system. In other embodiments, it may be applied to refrigeration cycle devices other than air conditioning systems. Here, a refrigeration cycle device is also called a refrigeration and air conditioning device, and a refrigeration and air conditioning device is a general term for devices that utilize refrigerants and refrigeration cycles, such as refrigerators and freezers, in addition to the air conditioning systems described above. More specifically, examples of refrigeration and air conditioning devices may include the above-mentioned air conditioning systems such as packaged air conditioners and multi-split air conditioners for buildings, heat source equipment such as chillers and chilling units, commercial refrigeration equipment such as showcases, refrigerators and freezers, unit coolers and ice makers, transport refrigeration equipment such as car air conditioners, and heat pump water heaters.

[0090] It should be noted that the embodiments described herein are not limited to those described above, and may include various modifications. For example, the embodiments described above are described in detail for clarity and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0091] 1...Air conditioner, 2...Refrigerant piping, 4...Indoor unit, 10...Outdoor unit, 11, 11B...Fan, 12, 12B...Fan guard, 13...Motor, 14...Stay, 15, 15B...Bell mouth, 16...Compressor, 17...Outdoor heat exchanger, 18...Electrical box, 19...Housing, 20, 20B...Propeller, 21...Hub, 22...Wing, 23...Leading edge, 24...Trailing edge, 25...Wing root, 26...Wing tip, 30, 40...Section, 31, 41...Wing root side section, 32...Intermediate section, 33, 42...Wing tip side section, 34, 35, 43...Transition section, 41...Wing root side section

Claims

1. A fan comprising a rotating body having a hub that rotates around a rotation axis and a plurality of blades, each of which is a forward-moving blade, connected to the hub, wherein each of the plurality of blades has a leading edge that, in the meridional plane of the blade, includes a root-side section having a generally first inclination A from the root to the tip, an intermediate section having a generally second inclination B, and an tip-side section having a generally third inclination C, wherein the first inclination A of the root-side section, the second inclination B of the intermediate section, and the third inclination C of the tip-side section satisfy the relationships B > 0, A > B, and C > B.

2. The fan according to claim 1, wherein the first inclination A of the wing root section, the second inclination B of the intermediate section, and the third inclination C of the wing tip section are, respectively, within the following ranges: 25 degrees < A < 45 degrees, 5 degrees < B < 15 degrees, and 25 degrees < C < 45 degrees.

3. The fan according to claim 2, wherein the average inclination of the leading edge from the wing root to the wingtip is in the range of 20 degrees to 40 degrees.

4. The fan according to claim 2, wherein the intermediate section is within the range of a radius from 20% to 80%, with the radius of the wing root defined as 0% and the radius of the wingtip as 100%, and the width of the intermediate section is at least 20%.

5. The fan according to claim 4, wherein the wing root section, the intermediate section, and the wing tip section are sections obtained by dividing the distance from the wing root to the wing tip into approximately three equal parts in the radial direction.

6. The fan according to claim 1, wherein each of the plurality of blades has a trailing edge, and is configured to be convex towards the fan discharge side at a position slightly inward from the trailing edge toward the leading edge between the midpoint of the trailing edge and the blade tip.

7. The fan according to claim 1, further comprising a bell mouth having a cylindrical portion, wherein the intermediate portion of the leading edge coincides with the inlet of the bell mouth or is located inside the inlet of the bell mouth.

8. The fan according to claim 1, further comprising a bell mouth having a cylindrical portion, wherein the entire trailing edge is located within the cylindrical portion of the bell mouth.

9. The fan according to claim 1, wherein each of the plurality of wings has a trailing edge that is positioned on the exhaust side of the height of the leading edge in the meridional plane over a range from the wing root to the wingtip, and the trailing edge comprises a first section having a negative slope and a second section having a positive slope in the meridional plane from the wing root to the wingtip.

10. An outdoor unit of an air conditioning system comprising a fan according to any one of claims 1 to 9, and an outdoor heat exchanger through which the air blown by the fan passes.

11. An air conditioning system comprising an outdoor unit as described in claim 10, and one or more indoor units connected to the outdoor unit via refrigerant piping.

12. A refrigeration cycle device comprising a fan according to any one of claims 1 to 9.

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