JP4863817B2 - Additional blade design method for axial fans - Google Patents

Description

  The present invention relates to an additional blade design method for an axial flow fan in which an additional blade is designed on a blade disposed on the outer periphery of a hub portion having a rotation center.

An axial fan (for example, a propeller fan) that sucks gas from the axial direction and blows it in the axial direction is applied to an outdoor unit, a ventilation fan, a fan, and the like of the air conditioner. The axial fan includes a plurality of blades arranged on the outer periphery of a hub portion having a rotation center, and the blades are formed in a three-dimensional curved surface shape.
When designing the blades of an axial fan, it is known to define a formula that specifies the circumferential cross-sectional shape and radial cross-sectional shape of the blade with several parameters, and to use this formula to design the blade. (For example, refer to Patent Document 1).
By the way, noise is generated in the axial fan due to a blade tip vortex generated on the outer peripheral side of the blade when the fan rotates. Conventionally, in order to suppress the generation of the blade tip vortex, a blade shape having an additional blade by partially changing the shape of the blade has been proposed (for example, see Patent Document 2).
Japanese Patent No. 3754244 JP 2005-105865 A

  However, the design method described in Patent Document 1 described above is a method of designing a three-dimensional curved wing that does not have additional wings, and it has been difficult to partially change the shape. For this reason, the work of designing a blade having an additional blade as described in Patent Document 2 is complicated, and it is difficult to determine the best blade shape.

  The present invention has been made in view of the above-described circumstances, and it is an object of the present invention to provide an additional blade design method for an axial fan capable of easily designing additional blades.

In order to solve the above-described problem, the present invention sets a coordinate system having the rotation center as an origin with respect to a plane perpendicular to the rotation axis, on a blade disposed on the outer periphery of the hub portion having the rotation center. , Set an arbitrary reference point shifted from the rotation center of the blade on the plane, set an arc of an arbitrary first radius centered on the reference point in the blade as a blade shape change start portion, The additional wing is designed by changing the wing shape at the wing shape change start part.
According to the present invention, an arbitrary reference point deviated from the rotation center of the blade is set, an arc having an arbitrary first radius centered on the reference point of the blade is set as the blade shape change start portion, and the blade Since the additional blade is designed by changing the blade shape at the shape change start part, it is possible to easily set the blade shape change start part substantially along the circumferential direction of the blade and easily design an additional blade suitable for noise reduction etc. can do.

  In the above configuration, the reference point is an arc having an arbitrary first angle with the radius from the rotation center to the tip of the tip of the blade leading edge as a center. It is preferable to set the end point of the obtained arc. In this case, it is preferable to set the first angle as a variable and change the first angle so that the position of the blade shape change start portion can be changed. According to this configuration, it is possible to easily design and change the design of the blade shape change start portion only by setting the numerical value of the first angle or changing the numerical value.

  Further, in the above configuration, when an additional blade is designed on the outer peripheral portion of the blade, it is preferable that the outer peripheral side of the blade is bent with respect to the blade shape change start portion. According to this configuration, it is possible to easily design a blade that reduces noise caused by the blade tip vortex.

  In the above configuration, when an additional blade is designed on the blade surface excluding the outer peripheral portion of the blade, it is preferable to design an additional blade that protrudes toward the suction surface side of the blade at the blade shape change start portion. According to this configuration, it is possible to easily design a blade that reduces noise caused by the airflow flowing in the vicinity of the blade surface.

  Further, in the above configuration, a mathematical formula for obtaining a change amount of the curved surface of the blade is defined by using the maximum change amount of the curved surface of the additional blade, the inclination change position of the additional blade, and the maximum change position of the additional blade as variables. Thus, it is preferable to design the additional wing. According to this configuration, it is possible to easily design the curved surface of the additional blade with only three variables: the maximum amount of change of the curved surface of the additional blade, the inclination change position of the additional blade, and the maximum change position of the additional blade. Can do.

  Further, in the above configuration, the mathematical formula for obtaining the amount of change in the curved surface of the additional blade is a first curve that smoothly represents a quadratic curve that smoothly connects between the tip of the blade leading edge of the blade and the inclination change position of the additional blade. A quadratic curve that smoothly connects between the maximum change position and the curved surface end position, and a second expression showing a quadratic curve that smoothly connects the inclination change position and the maximum change position of the additional blade. It is preferable to be defined using and in the third formula. According to this configuration, the shape change of the additional wing can be smoothed, and a complicated curved surface shape can be designed.

  In the present invention, an arbitrary reference point deviated from the rotation center of the blade is set, an arc having an arbitrary first radius centered on the reference point of the blade is set as a blade shape change start portion, and the blade shape change Since the additional blade is designed by changing the blade shape at the start part, it is possible to easily set the blade shape change start part substantially along the circumferential direction of the blade, and to easily design an additional blade suitable for noise reduction. it can.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an outdoor unit to which a propeller fan according to an embodiment of an axial fan of the present invention is applied. The outdoor unit 10 is disposed outside and is connected to an indoor unit (not shown) disposed on the ceiling or wall of the room by piping to constitute an air conditioner. The air conditioner is configured to be connected to the outdoor unit 10 and the indoor unit. Cooling operation and heating operation are performed by flowing the refrigerant through a refrigerant circuit composed of a machine. The outdoor unit 10 exchanges heat between the outside air and the refrigerant, condenses the refrigerant during the cooling operation and releases heat to the outside air, and evaporates the refrigerant during the heating operation to take in heat from the outside air.

  The outdoor unit 10 includes a compressor 12, an accumulator 13, a four-way valve 14, a heat exchanger 15, and a propeller fan 16 as an axial fan in a casing 11. As shown in FIG. 2, the propeller fan 16 is connected to a fan motor 17, and the fan motor 17 is supported by a support plate 18 and disposed in front of the heat exchanger 15. By driving the propeller fan 16 by the fan motor 17, air (outside air) is blown from the inside to the outside of the heat exchanger 15 as indicated by an arrow A in FIG. 2, and the refrigerant in the heat exchanger 15 and the outside air exchange heat. Is done.

  As shown in FIG. 3, the propeller fan 16 includes a hub portion 19 and a plurality of (for example, three) blades 20 having the same shape and arranged at a predetermined pitch on the outer periphery of the hub portion 19. Configured. These hub part 19 and wing | blade 20 are integrally resin-molded, for example.

  The hub 19 has a motor shaft 21 (FIG. 2) of the fan motor 17 inserted through the rotation center 19 </ b> A, and rotates the blades 20 in the direction of arrow N in FIG. 3 by driving the fan motor 17. The hub portion 19 has an outer diameter that is substantially triangular.

  As shown in FIGS. 3 and 4, the blade 20 is rotated in the direction of arrow N from the blade leading edge 22 side toward the blade trailing edge 23 side along the blade negative pressure surface (blade back surface) 24F. 2) and the entire air is blown from the back side of the propeller fan 16 to the front side in the direction of arrow A in FIG.

As shown in FIG. 4, the blade 20 is formed in a three-dimensional curved surface shape in which the blade surface is twisted spatially and the blade leading edge 22 side is largely inclined forward to the air suction side.
By the way, when the propeller fan 16 rotates, a blade tip vortex is generated in the vicinity of the outer periphery of the blade 20 (near the blade trailing edge 23) due to a flow that is drawn from the blade pressure surface (blade front surface) 24S into the blade suction surface 24F. Are known. And it is known that this blade tip vortex grows and peels off from the blade surface is the cause of increasing the noise (air blowing sound).
Therefore, in the blade 20 of the present embodiment, an additional blade 20B formed so as to bend the outer peripheral portion (blade periphery) of the blade 20 from the blade leading edge 22 side to the blade trailing edge 23 side to the blade suction surface 24F side. Is formed. By providing this additional blade 20B, the blade tip vortex generated in the vicinity of the outer periphery of the blade 20 is reduced, the growth of the blade tip vortex is suppressed, and the separation from the blade surface is suppressed, and the noise caused by the blade tip vortex is reduced. be able to.

Hereinafter, a method of designing the blade 20 using an arithmetic processing device capable of arithmetic processing such as a personal computer will be described. When designing the blade 20, it is roughly designed at a basic blade design stage for designing a blade having only a basic curved surface (hereinafter referred to as a basic blade 20A) without the additional blade 20B, and at the basic blade design stage. There is an additional blade design stage in which the shape of the basic blade 20A is partially changed to design the additional blade 20B. Through these steps, coordinate data indicating the three-dimensional shape of the blade 20 can be obtained.
This coordinate data can be used as design data by being input to, for example, a three-dimensional CAD (Computer Aided Design), and this design data can be used, for example, to manufacture a mold used to mold the blade 20. By being input to the die processing apparatus, it can be used as processing data.

<Basic wing design stage>
First, the design of the basic wing 20A will be described. As shown in FIG. 5, the shape (three-dimensional shape) of the basic blade 20A is a circumferential cross-sectional shape and a radial direction in a coordinate system having a rotation center 19A in a plane perpendicular to the rotation axis of the propeller fan 16 as an origin O. It is defined using two cross-sectional shapes. Specifically, emphasis is placed on the circumferential cross-sectional shape important for determining the blowing performance of the propeller fan 16, the circumferential cross-sectional shape at an arbitrary radius r from the origin O is defined by a mathematical formula, and the radial cross-sectional shape is determined. In order to change while maintaining the circumferential sectional shape, the difference (r−R) between the maximum radius R of the basic wing 20A and the arbitrary radius r is added to the circumferential sectional shape. Defined by.

  FIG. 6 shows a circumferential cross-sectional shape of the basic blade 20A at an arbitrary radius r from the origin O. The curve 25 indicating the circumferential cross-sectional shape of the basic blade 20A is obtained by subtracting the curve 27 from the chord line 26 that is the basis of the blade cross-sectional shape. The next curves 28 and 29 are connected at their respective peak positions. Here, the horizontal axis of FIG. 6 is the circumferential angle θ of the basic blade 20A that increases clockwise from the horizontal axis X passing through the origin O of FIG. 5, and the vertical axis is the blade height H of the basic blade 20A. .

  By adding a relational expression (r-R) in the radial direction of the basic wing 20A to the mathematical expression representing the circumferential cross-sectional shape of the wing 20 indicated by the curve 25, the three-dimensional shape of the basic wing 20A is represented by the mathematical expression (1). , (2).

ここで、Ｗ₁（ｒ）は反り前半角、Ｗ₂（ｒ）は反り後半角であり、曲線２７のピーク位置を決定するパラメータであって、後述の式（８）、（９）の如く半径ｒの関数である。また、θ_S（ｒ）は基本翼２０Ａの開始角度（翼前縁２２側）を示すパラメータであり、半径ｒの関数である。

Here, W ₁ (r) is the _first half angle of the warp, and W ₂ (r) is the _second half angle of the warp, and is a parameter for determining the peak position of the curve 27, as shown in equations (8) and (9) described later. It is a function of the radius r. Θ _S (r) is a parameter indicating the starting angle (on the blade leading edge 22 side) of the basic blade 20A, and is a function of the radius r.

Further, θ _L (r) in the equations (1) and (2) is a parameter indicating the angle range of the basic blade 20A, and is a function of the radius r and is defined by the following equation (3).

ここで、θ_E（ｒ）は基本翼２０Ａの終了角度（翼後縁２３側）を示すパラメータであり、半径ｒの関数であって次式（４）で示される。また、ＳＳ（ｒ）は翼２０の翼前縁２２位置を示すパラメータであり、基本翼２０Ａの上面投影図から設定され、次式（５）の如く半径ｒの関数として示される。

Here, θ _E (r) is a parameter indicating the end angle (blade trailing edge 23 side) of the basic blade 20A, and is a function of the radius r and is expressed by the following equation (4). SS (r) is a parameter indicating the position of the blade leading edge 22 of the blade 20, is set from the top projection of the basic blade 20A, and is expressed as a function of the radius r as in the following equation (5).

これらの式（４）、（５）において、Ａ₁、Ａ₂、Ｂ₁、Ｂ₂、Ｃ₁、Ｃ₂、Ｄ₁、Ｄ₂はそれぞれ定数である。

In these formulas (4) and (5), A ₁ , A ₂ , B ₁ , B ₂ , C ₁ , C ₂ , D ₁ , and D ₂ are constants.

Further, H _L (r) in the equations (1) and (2) is a parameter indicating the height range of the basic blade 20A, and is a function of the radius r and is represented by the following equation (6).

ここで、Ｈ_E（ｒ）は、基本翼２０Ａの終了高さ（翼後縁２３側）であり、任意の値に設定される。また、Ｈ_S（ｒ）は翼２０の開始高さ（翼前縁２２側）を示すパラメータであり、ハブ部１９との接続位置を考慮して設定され、次式（７）の如く半径ｒの関数として示される。

Here, H _E (r) is the end height of the basic blade 20A (the blade trailing edge 23 side), and is set to an arbitrary value. H _S (r) is a parameter indicating the starting height of the blade 20 (blade leading edge 22 side), and is set in consideration of the connection position with the hub portion 19, and has a radius r as shown in the following equation (7). As a function of

このＡ₃、Ｂ₃、Ｃ₃、Ｄ₃も定数である。

These A ₃ , B ₃ , C ₃ and D ₃ are also constants.

W ₁ (r) and W ₂ (r) are respectively calculated by assuming that the blade inflection point distribution ratio that determines the ratio of the _first half angle W ₁ (r) and the _second half angle W ₂ (r) is P. It is shown by the following formulas (8) and (9).

さらに、式（１）、（２）中のＤ（ｒ）は、基本翼２０Ａの最大反り深さ（つまり、図６の翼弦直線２６と曲線２５との最大距離）を示すパラメータであり、次式（１０）に示す如く半径ｒの関数である。

Further, D (r) in the equations (1) and (2) is a parameter indicating the maximum warp depth of the basic wing 20A (that is, the maximum distance between the chord line 26 and the curve 25 in FIG. 6). It is a function of the radius r as shown in the following equation (10).

ここで、Ｄ_Oは基準最大反り深さを示すパラメータであり、基本翼２０Ａの最大半径Ｒ位置における最大反り深さＤ（Ｒ）を示す。

Here, D _O is a parameter indicating the reference maximum warp depth, and indicates the maximum warp depth D (R) at the position of the maximum radius R of the basic blade 20A.

  The three-dimensional shape of the basic wing 20A is determined by the above formulas (1) to (10). In this determination, the outermost peripheral position of the basic wing 20A, that is, the maximum radius R position is used as a reference.

Further, in the expressions (4), (5), and (7), the relational expression (r-R) of the radial cross-sectional shape of the basic blade 20A is added. Formulas (4), (5), respectively defining the end angle θ _E (r) of the basic blade 20A, the blade leading edge 22 position SS (r), and the starting height H _S (r) of the basic blade 20A, respectively. (7) is defined by a third-order polynomial so that when a plurality of basic blades 20A are combined to form one propeller fan 16, the basic blades 20A do not interfere with each other, and the blade leading edge 22 side of the basic blade 20A Consideration is given so as to flexibly cope with restrictions on the shape and the shape of the blade trailing edge 23 side.

Furthermore, the starting angle θ _S (r) of the basic wing 20A is defined to define a curve 25 indicating the circumferential cross-sectional shape of the basic wing 20A at each radial position of the basic wing 20A, as indicated by a dashed line in FIG. This is the starting point. The actual basic blade 20A is not necessary to reduce the distortion of the blade surface by using the curve 25 defined between the start angle θ _S (r) and the end angle θ _E (r) of the basic blade 20A. It is formed by excising a part. This cutting position is the blade leading edge 22 position SS (r) of the basic blade 20A. Further, depending on the value of the starting angle θ _S (r) of the basic wing 20A, it is possible to set how the basic wing 20A expands in the radial direction and twist.

  Next, a procedure for designing the three-dimensional basic wing 20 </ b> A in the propeller fan 16 using the above formulas (1) to (10) will be described.

First, a numerical value is set for the maximum radius R of the basic blade 20A (for example, R = 230 (mm)), and the reference maximum warp depth D is considered in consideration of the angle of attack α on the blade leading edge 22 side and the incident angle β of air. Set numerical values for _O and blade inflection point distribution rate P. In addition, the coefficient An, Bn, the blade end angle θ _E (R) and the blade end height H _E (R) at the outermost periphery of the blade, and the term of the relational expression (r−R) related to the radial cross-sectional shape of the basic blade 20A Cn and Dn are set numerically. Further, the starting angle θ _S (r) of the basic blade 20A is set to zero (θ _S (r) = 0).

  Here, the angle of attack α of the basic blade 20A is the angle of the blade leading edge 22 with respect to the plane 30 perpendicular to the rotation center 19A of the propeller fan 16 (hub portion 19), as shown in FIG. Further, the incident angle β of air is an angle at which air flows into the propeller fan 16 with respect to the plane 30. The incident angle β of air varies depending on the interference of air between the blades 20 of the propeller fan 16 and the radial positions of the basic blades 20A. Determine empirically from fan data. Further, if the angle of attack α of the basic blade 20A is too small, it cannot cope with the change of the air flow, and the propeller fan 16 may be stalled. Therefore, an appropriate angle larger than the incident angle β of air is appropriate. Set to an angle.

As shown in FIG. 7, in order to set the angle of attack α of the basic blade 20A to 12 degrees or more, for example, when the blade inflection point distribution rate P is 65%, the value of the reference maximum warp depth D _O is 40 (mm) or more is desirable. In this embodiment, numerical values are set to α = 12 (degrees), P = 65 (%), and D _O = 40 (mm).

Next, parameters R, D _O , P, θ _E (R), H _E (R), A _n , B _n , C _n , D _n , θ _S (r) set numerically as described above. Substituting the values into equations (4), (5), (3), (7), and (6), respectively, the parameters θ _E (r), SS (r), θ _L (r), H _S (r ), H _L (r) are calculated, and are substituted into equations (8) and (9), respectively, to calculate parameters W ₁ (r) and W ₂ (r), respectively, and further substituted into equation (10). Then, the parameter D (r) is calculated.

Next, the above-described parameter θ _E (at the respective radial positions (for example, r = 250, 230, 210, 190, 170, 150, 130, 110, 90, 70, 50, 30...)) Of the basic blade 20A. r), SS (r), θ _L (r), H _S (r), H _L (r), W ₁ (r), W ₂ (r) and D (r) are calculated. This is shown in FIG. In FIG. 8, the values of the parameters θ _S (r) and H _E (r) are also displayed.

  Thereafter, the numerical values of FIG. 8 are substituted into the equations (1) and (2), and the circumferential direction of the basic blade 20A at each radial position (r = 250, 230, 210,...) Of the basic blade 20A. Formulas relating to θ for displaying the cross-sectional shape are obtained, and then the value of the blade height H of the blade 20 is calculated by substituting the numerical values of θ into these formulas. Thereby, a large number of coordinate data of H (θ, r) representing the three-dimensional shape of the basic wing 20A is obtained as a point group. The above is the design method of the basic wing 20A.

  According to the design method of the basic blade 20A, the basic shape of the blade 20 of the propeller fan 16 is configured by defining the circumferential cross-sectional shape and the radial cross-sectional shape using the formulas (1) to (10). Therefore, since the cross-sectional shape of the blade 20 can be designed using different quadratic curves 28 and 29 shown in FIG. 6, the blade 20 having a complicated shape can be designed and manufactured. For this reason, the numerical formulas of various parameters are changed to make the blade surface of the blade 20 have a smooth shape, preventing the occurrence of resistance due to the extreme curvature change on the blade surface, and the maximum warp depth of the blade 20 Adjust the numerical value of D (r) to ensure an appropriate air volume by the propeller fan 16, or adjust the position of the maximum warp depth D (r) of the blade 20 using the blade inflection point distribution rate P. It is possible to easily clarify the difference in operation between the blade leading edge 22 side and the blade trailing edge 23 side of the blade 20. As a result, the blade 20 of the propeller fan 16 having a wide application range can be realized.

<Additional wing design stage>
Next, a method for designing the additional blade 20B by partially changing the shape of the basic blade 20A will be described. As shown in FIG. 9, in a coordinate system having an origin O as a rotation center 19A in a plane perpendicular to the rotation axis of the propeller fan 16, a reference point O ′ deviated from the origin O is set on this plane. A circle e1 having a radius R1 centered on O ′ is drawn, and an arc 20a-20a ′ where the circle e1 and the basic blade 20A overlap is set as a blade shape change start portion TS that becomes a bending start portion of the additional blade 20B. .

  Specifically, in order to make one end (upstream end portion in the rotation direction) of the blade shape change start portion TS coincide with the tip end portion (hereinafter referred to as the blade outer peripheral tip portion) 20a of the blade leading edge 22 of the basic blade 20A. A circular arc OO ′ having an arbitrary first angle θa having a radius R1 from the origin O and having a radius R1 centered on the outer peripheral tip 20a is then drawn. By calculating a circle e1 passing through the blade outer peripheral tip 20a with O ′ as the center, the coordinates of the arc 20a-20a ′ where the circle e1 and the basic blade 20A overlap are specified. Here, the first angle θa is an angle that increases clockwise from the horizontal axis X passing through the origin O and the blade outer peripheral tip 20a around the blade outer peripheral tip 20a, and the radius (first radius) of the circle e1 Ra is the distance between the reference point O ′ and the blade outer peripheral tip a.

  Actually, using the coordinate data of the blade outer peripheral tip 20a, the first angle θa is used as a variable to define a mathematical formula for calculating the coordinates of the arc 20a-20a ′, and by using this mathematical formula, The position of the blade shape change start part TS can be calculated simply by specifying the numerical value of the angle θa. In this case, the bending change range assigned to the additional blade 20B can be increased by increasing the first angle θa. A circle e0 shown in FIG. 9 is a circle drawn with the maximum radius R of the basic wing 20A.

The blade shape change start portion TS is determined by the above-described method. The blade shape change start portion TS determines only the bending start portion of the additional blade 20B, and the curved surface shape (blade height) of the additional blade 20B is determined. Equivalent) is determined as follows.
FIG. 10 shows a sectional view in the radial direction of the blade 20 (an OY′-Y sectional view of FIG. 9). The curved surface of the additional blade 20B is set by defining a change amount h with respect to the blade height H (see FIG. 6) of the basic blade 20A by a mathematical expression.

In the present embodiment, the amount of change h of the curved surface of the additional blade 20B is 3 of the maximum amount of change d of the curved surface of the additional blade 20B, the inclination change position l of the additional blade 20B, and the maximum change position m of the additional blade 20B. It is defined by a formula with one value as a variable.
Here, the circumferential cross-sectional shape (curved surface shape on the arc 20a-20a ′) of the outermost periphery of the additional blade 20B is shown in FIG. The horizontal axis in FIG. 11 is the circumferential angle θ of the basic blade 20A that increases clockwise from the horizontal axis X passing through the origin O and the blade outer peripheral tip a in FIG. 9, and the vertical axis is the amount of change h. A curve 35 indicating the amount of change h is a quadratic curve 35a (first equation) that smoothly connects the blade outer peripheral tip 20a and the inclination change position l of the additional blade 20B, and the inclination change position l and the maximum change d. It is constituted by a quadratic curve 35b (second equation) that smoothly connects the position (maximum change position) and a quadratic curve 35b (third equation) that smoothly connects the position of the maximum change amount d and the curved surface end position. The
Specifically, when the blade surface position in the blade outer peripheral portion (arc 20a-c) specified by the circumferential angle θ is α (a ≦ α <c), the amount of change h of the curved surface of the additional blade 20B is They are defined by equations (11), (12), and (13) corresponding to the quadratic curves 35a, 35b, and 35c, respectively.

ここで、ｎは、図９中のｃの位置に相当する曲面の変化終了位置を示すパラメータであり、ｄ’は傾き変化量を示すパラメータであり、ｈｅは、曲面終了位置における曲面の変化量を示すパラメータである。これらパラメータｎ、ｄ’、ｈｅは、予め設定したデフォルト値を適用してもよいし、あるいは、３つの変数（追加翼２０Ｂの曲面の最大変化量ｄ、傾き変化位置ｌ及び最大変化位置ｍ）を用いた数式を定義し、この数式によってパラメータｎ、ｄ’、ｈｅを設定するようにしてもよい。

Here, n is a parameter indicating the change end position of the curved surface corresponding to the position c in FIG. 9, d ′ is a parameter indicating the amount of change in inclination, and he is the change amount of the curved surface at the end position of the curved surface. It is a parameter which shows. For these parameters n, d ′, and he, default values set in advance may be applied, or three variables (the maximum change amount d of the curved surface of the additional blade 20B, the inclination change position l, and the maximum change position m). May be defined, and the parameters n, d ′, and he may be set by the equation.

  Therefore, by specifying numerically the maximum change amount d of the curved surface of the additional blade 20B, the inclination change position l of the additional blade 20B, and the maximum change position m of the additional blade 20B, the change amount h of the curved surface of the additional blade 20B can be reduced. A value is calculated. Then, based on the numerical data of the change amount h and the coordinate data of the basic wing 20A, the coordinate data of the wing 20 provided with the additional wing 20B by partially changing the shape of the basic wing 20A can be obtained. . The above is the method for designing the additional blade 20B.

According to the design method of this additional blade 20B, the blade shape change start portion TS of the basic blade 20A is rotated at the rotation center 19A (origin O) of the blade 20 around the blade outer peripheral tip 20a as shown in FIG. Since the first angle θa corresponding to the inner angle of the arc OO ′ passing through is defined as a variable, the blade shape change start portion TS can be easily designed and changed.
In addition, a reference point O ′ deviated from the rotation center 19A (origin O) of the blade 20 is set in accordance with the first angle θa, and an arc aa passing through the blade outer peripheral tip 20a around the reference point O ′. 'Because the top is set as the blade shape change start part TS, the end of the blade shape change start part TS (the upstream side end in the rotation direction) always satisfies the condition that it matches the blade outer peripheral tip a of the basic blade 20A. In the state, the bending change range allocated to the additional blade 20B can be freely adjusted. Thereby, the design freedom degree of the wing | blade shape change start part TS is fully securable, avoiding the increase in the wind noise when the wing | blade outer periphery front-end | tip part 20a cuts a wind.

Further, the amount of change h indicating the curved surface of the additional blade 20B is three variables: the maximum amount of change d of the curved surface of the additional blade 20B, the inclination change position l of the additional blade 20B, and the maximum change position m of the additional blade 20B. Since they are defined and configured, it is easy to intuitively understand the variable for numerical designation, and the curved surface of the additional blade 20B can be easily designed or changed.
In addition, since the amount of change h is composed of the curve 35 including the three quadratic curves 35a, 35b, and 35c, the shape change from the blade outer peripheral tip 20a can be smoothed, and a complicated curved surface shape can be obtained. Can be easily designed in a shape that suppresses the resistance to the airflow during fan rotation.
Therefore, according to the design method of the additional blade 20B described above, the blade shape change start portion TS and the amount of change h that define the additional blade 20B can be easily designed. The wing 20B can be easily designed.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to this, A various change implementation is possible. For example, in the above embodiment, the case where the outer peripheral portion (blade circumference) of the blade 20 is changed in shape to the blade suction surface 24F side and the additional blade 20B is provided has been described. You may make it change and provide the additional wing | blade 20B.
Further, in the above embodiment, when designing the blade shape change start portion TS of the additional blade 20B, the case where one end of the blade shape change start portion TS of the additional blade 20B is made to coincide with the blade outer peripheral tip portion 20a, Not limited to this.

For example, as shown in FIG. 12, after setting a reference point O ′ deviated from the rotation center 19A (origin O) of the blade 20 based on the first angle θa, a circle e1 centered on the reference point O ′ is set. By setting the radius (first radius) Ra to an arbitrary radius, a circle e1 passing inside the blade outer peripheral tip 20a is set, and an arc 20a ″ -20a ′ where this circle e1 and the basic blade 20A overlap is set as the blade The shape change start unit TS may be used. Actually, the position of the blade shape change start part TS is calculated by defining numerical values of the first angle θa and the first radius Ra by defining a mathematical formula with the first angle θa and the first radius Ra as variables. Is possible.
In this case, the blade shape change start part TS substantially along the circumferential direction of the blade 20 can be set on the blade surface excluding the outer peripheral portion of the blade 20. The blade shape change start portion TS is preferably provided with an additional blade protruding toward the blade suction surface 24F, for example, one or a plurality of plate-shaped or protruding additional blades. By providing such an additional blade, it is possible to easily design a blade suitable for noise reduction by preventing separation of airflow and vortex generation near the blade surface.

In the above embodiment, the reference point O ′ is centered on the tip of the blade leading edge 22 (blade outer periphery tip 20a) from the rotation center 19A (origin O) of the blade 20 to the rotation center 19A and the tip. The case where the arc is set to the end point of an arc obtained when an arc of an arbitrary first angle θa having a radius R1 as the distance to the part has been described, but is not limited to this, and the rotation center 19A (origin O ) May be set numerically, and the reference point O ′ may be set based on this deviation amount. Also in this case, it is possible to easily set the blade shape change start portion TS substantially along the circumferential direction of the blade 20.
Moreover, although the case where this invention was applied to the propeller fan 16 of 3 sheets fan was described in the said embodiment, it is applicable not only to this but various axial fans, such as a 2 sheet fan and a 4 sheet fan. . Further, the present invention is not limited to the axial fan used for the outdoor unit 10 but can be widely applied to an axial fan used for a ventilation fan, a fan, or the like.

It is a figure which shows the outdoor unit with which the propeller fan which concerns on one Embodiment of the axial fan of this invention was applied. It is a figure which shows the principal part of an outdoor unit. It is a perspective view of a propeller fan. It is a side view of a propeller fan. It is a figure which shows the shape of the basic wing | blade of a propeller fan. It is a figure which shows the circumferential direction cross-sectional shape of the basic wing | blade in the radius r position of FIG. It is a graph which shows the relationship between the angle of attack of the blade leading edge, the blade inflection point distribution ratio, and the reference maximum warp depth of the blade in the basic wing. It is a graph which shows the value of the parameter in each radial direction position of a basic wing. It is a figure which shows the wing | blade shape change start part in a basic wing | blade. It is sectional drawing in the radial direction of a wing | blade. It is a figure which shows the circumferential direction cross-sectional shape of the outermost periphery of an additional wing | blade. It is a figure which shows the modification of the wing | blade shape change start part in a basic wing | blade.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Outdoor unit 16 Propeller fan 19 Hub part 19A Rotation center 20 Blade 20A Basic blade 20B Additional blade 22 Blade leading edge 23 Blade trailing edge 24F Blade suction surface 20a Blade outer periphery tip θa First angle O Origin O 'Reference point 35 Curve 35a , 35b, 35c Quadratic curve h Change amount indicating curved surface of additional blade d Maximum change amount of curved surface of additional blade l Inclination change position of additional blade m Maximum change position of additional blade TS Blade shape change start section

Claims (7)

  A coordinate system with the rotation center as the origin is set on the wing arranged on the outer periphery of the hub portion having the rotation center with respect to a plane perpendicular to the rotation axis, and deviated from the rotation center of the wing on the plane. An arbitrary reference point is set, an arc having an arbitrary first radius centered on the reference point in the wing is set as a wing shape change start portion, and the wing shape change is changed at the wing shape change start portion. An additional blade design method for an axial fan characterized by designing an additional blade. The additional blade design method for an axial fan according to claim 1,
The reference point is the arc obtained when an arc of an arbitrary first angle is drawn with the distance between the rotation center and the tip as a radius from the rotation center with the tip of the blade leading edge as the center. A method for designing an additional blade of an axial fan, characterized by being set at the end point of the axial flow fan. The method for designing an additional blade of an axial fan according to claim 2,
An additional blade design method for an axial fan, wherein the first angle is set as a variable, and the position of the blade shape change start portion can be changed by changing the first angle. In the additional blade design method of the axial fan according to any one of claims 1 to 3,
When designing an additional blade on the outer peripheral portion of the blade, the additional blade design method for an axial flow fan is designed such that the outer peripheral side of the blade is bent with respect to the blade shape change start portion. In the additional blade design method of the axial fan according to any one of claims 1 to 3,
When an additional blade is designed on the blade surface excluding the outer peripheral portion of the blade, an additional blade projecting toward the suction surface side of the blade is designed at the blade shape change start portion. Method. In the additional blade design method of the axial fan according to any one of claims 1 to 5,
The additional blade is defined by defining a mathematical expression for obtaining the amount of change in the curved surface of the blade, using the maximum amount of variation of the curved surface of the additional blade, the inclination variation position of the additional blade, and the maximum variation position of the additional blade as variables. An additional blade design method for an axial fan characterized by designing The additional blade design method for an axial fan according to claim 6,
The mathematical formula for obtaining the amount of change in the curved surface of the additional blade is a first equation showing a quadratic curve that smoothly connects between the tip of the blade leading edge of the blade and the inclination change position of the additional blade, and the change in inclination. A second equation showing a quadratic curve smoothly connecting the position and the maximum change position of the additional wing, and a third equation showing a quadratic curve smoothly connecting the maximum change position and the curved surface end position; A method for designing an additional blade of an axial fan, characterized in that

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