KR880000522B1 - Axial-flow fan - Google Patents

Abstract

An axial flow fan for reducing noise caused by air-flow has parameters satifying following conditions that BR=0.15-0.2 DT, DB=1.01-1.05 DT, lx=0-0.04 DT where BR; half radius of curved edge of the outer frame, DT; outer radius of the fan DB; inner radius of the bell mouth, lx; distance between back part of the outer wing of the fan and the end part of the duct.

Description

Axial flow fan

1 is a front shape diagram of a conventional axial flow wing.

2 is an exploded perspective view of an axial fan according to an embodiment of the present invention.

θ의 정의를 나타낸 전면(前面)형상도.3 is a diagram illustrating the above embodiment.

Front surface diagram showing the definition of θ.

z의 정의를 나타낸 회전축을 포함한 평면에 대한 회전투영도.4 is

Rotational projection about the plane containing the axis of rotation representing the definition of z.

5 is a cross-sectional view showing the tip of the wing.

6 is a front view showing the mutual position of the wings.

7 is a cross-sectional view of the wing showing the relative relationship of flow to the wing.

z의 변화에 대한 비소음 레벨과 개방점소음 레벨의 값을 보인 실험결과에 의한 특성도.8 is

Characteristic diagram from the experimental results showing the values of non-noise level and open-point noise level for the change of z.

θ의 변화에 대한 비소음레벨과 개방소음레벨의 값을 나타낸 실험결과에 의한 특성도.9 is

Characteristic diagram from the experimental results showing the values of non-noise level and open noise level with respect to θ change.

10 is a characteristic diagram based on experimental results showing the values of the noise level and the open point noise level for a change in θ t.

t의 변화에 대한 비소음레벨 ks와 개방점소음레벨의 값을 나타낸 실험결과에 의한 특성도.11 is

Characteristic diagram from the experimental results showing the values of the non-noise level ks and the open point noise level for the change of t.

12 is a side view showing wings and bellmouth.

13 is a characteristic diagram showing the relationship between the size of the R portion of the bell mouse and the opening point level.

* Explanation of symbols for main parts of the drawings

1: wing

1b: Wing leading edge

1a: wing tip

1b ': leading edge of wing in front projection

1 ': Wings in front projection

1c: wing trailing edge

1a ': wing tip in front projection

1c ': wing trailing edge in front projection

1d: wing outer peripheral

4: direction of rotation

5c: relative camber wire

1d ': Wing circumference in front projection

5: Camber line

6: parallel axis of rotation axis

2: boss

5a: wing pressure surface

7: wing surface inflow vector

3 ': axis of rotation

5b: wing pressure surface

8: pressure-side peeling area

9: centrifugal force due to flow between wings

9a: Normal component force of the blade pressing of centrifugal force

9b: Parallel component of the pressure-sensitive surface of the wing of centrifugal force

Rt: radius of outer periphery of the wing

Re: Wing tip position radius

Rb: Boss radius

R: radius

R _R : Ikhyeon Line Center

P _R ': Center of Ikji Line in the front projection

Pt: Ikji center point of the outer circumference of the wing

Pt ': Center point of the guiding line of the outer periphery of the wing in the front projection

Pb: Ikseon center point of boss outsourcing

Pb ': Iksi Center Point of Boss Outsourcing in Total Dose

O: origin of boss in front projection

X: X axis

: 반경R에 있어서의 익현선 중심점의 X축에 대한 각도

Is the angle to the X axis of the center of the chord line at radius R.

Sc: Plane perpendicular to the axis of rotation past Pb

Ls is the distance between the center line of the leading line of radius R and the Sc plane

: Sc 평면과 선분 Pb. P_R의 이루는 각도

: Sc plane and line segment Pb. Angle of P _R

L: Length of blade string P _R : Reference radius of arc blade

DB: Inner diameter of Bell Mausu θ: Camber angle

t: Pitch in the circumferential direction of the blade BR: Size of R part of the bell mouse

: 날게 엇갈림각 DT : 임펠러의 외경

: Flying angle DT: Outer diameter of impeller

ℓx: Distance between the bellows water end and the trailing edge of the impeller outer circumference

The present invention relates to an axial flow fan for use in a ventilation fan, an air conditioner, and the like, and more particularly, to provide an axial flow fan capable of lowering the aerodynamic noise.

Axial fans are widely used in air conditioners, ventilation fans, etc., and it is very socially important to reduce the noise generated by the fans as much as possible. However, the design method of the low noise fan that lowers the noise generated by the fan as much as possible and does not lower the aerodynamic performance of the fan has not been established, and only the trial and error design method corresponding to each product has been applied. .

Among these prior arts, many methods have been used, such as forming the front shape of an impeller projected in Japanese Patent Application No. 50-39241 such as to protrude in the rotational direction.

Figure 1 shows the front phenomenon of the impeller according to the patent, 1 is the impeller wing, 2 is the boss attaching the wing (1), 1a is the tip of the wing (1), R is the outer radius of the impeller, Re is the wing This is the radius of the tip 1a.

In the conventional impeller of this type, there is no clear judgment technique regarding the method of determining the position of the circumferential part and the method of determining the leading edge, and a method of simply defining the shape only by the specificity of the front shape has been applied.

In FIG. 1, the blade tip portion 1a is located at a radius ratio Re / Rt = 0.88, and there is no Re / Rt ≒ 1.0 near the outer circumference of the impeller, thereby substantially reducing the area of the wing outer circumference having the largest portion. As a result, noise is increased by causing a decrease in aerodynamic performance.

The tip of the blade in the axial fan is very important from the aerodynamic point of view. The fact that the shape has a large R shape in the direction of the rotation axis is a great resistance to the fluid and the induction of the leading edge peeling from the leading edge of the blade It increases the noise generated from the wing surface.

In addition, in the conventional impeller, the flow of the wing is considered to be a simple two-dimensional flow, and the shape is determined. Therefore, the noise characteristics at the opening point can be improved, but the noise characteristics at the time of static pressure generation, which is the actual fan use mode, can be determined. There is no big improvement.

Therefore, the fan of the shape such as Japanese Special Public Service No. 50-939241 has no three-dimensional handling of the wing shape. Therefore, even in the fan configuration, the noise characteristics can be dramatically improved and an ultra-low noise axial fan can be constructed. There is no.

The present invention and the other invention of the present invention was made in order to improve the shortcomings of the conventional axial flow fan, and an object of the present invention is to provide an axial impeller with ultra low noise, which has not existed until now by clarifying the three-dimensional shape of the impeller.

An embodiment of the present invention will be described with reference to the drawings.

2 is a perspective view of the axial flow fan according to this embodiment in the shape of three wings, and the bell mouse portion is disassembled and displayed. 1 is a three-dimensional wing, 1a is a wing tip, 1b is a wing leading edge, 1c is a wing trailing edge, 1d is a wing outer periphery, 2 is a boss for attaching a wing (1), 3 is an axis of rotation of the impeller, and 4 is The direction of rotation.

This wing, as you know in the drawing, is unique in the shape of a wing and has not existed until now.

Specifically, the factors constituting the axial flow fan according to the present invention are shown.

The impeller is designed to specifically define the three-dimensional shape of the wing by clarifying various factors that make up the fan, and is the optimal shape obtained from the vast test results. As an important parameter for determining the three-dimensional shape of the axial fan, the present invention defines the position of the blade center line P _R of the blade.

3 is a projection view when the blade 1 is projected on a plane orthogonal to the rotation axis 3, 1 'is a wing shape on the projection surface of the blade 1, 2 is a boss, 3 is a rotation axis, and the rotation axis 3 ) is the arc 1bR'-P _'R -1CR' wing cross-sectional shape in the plane when the cutting blade (1) in a cylindrical surface of radius R in.

Here, P _R 'is the center point of circular arc 1bR'-1CR', and becomes the midpoint of the free line on a projection surface.

In order to clarify the position of P _R ′ on the projection surface, the boss subordinate line center point on the projection surface at the time of cutting the blade 1 from the cylindrical surface of the boss radius Rb is Pb 'and A coordinate system with a straight line Pb'-0 connecting the position 0 on the projection surface on the X axis and 0 as the origin is formed on the projection surface.

Pθ 'chord line is the center line (P _R' represents a chord center line trajectory tangent to the radius (R) with an angle of _{(Pb'-P R '-Pt'} ) in).

In addition, the code | symbol with a dash (') symbol shows each part in a projection surface.

로 하고, 거리를 R로 하면, P_R'의 위치는 (R,

)라고 하는 극좌표로 표현할 수 있다.The angle between P _R '-0 and the X axis in the coordinate system

If the distance is R, the position of P _R 'is (R,

Can be expressed in polar coordinates.

라 하면

(Rt : 날개끝반경, Rb : 보스반경)로 부여하고

=40°-50°로 하고 있다.In this invention, the angle formed by the straight line Pt'-0 and the X-axis

If

(Rt: radius of wing tip, Rb: radius of boss)

= 40 ° -50 °.

In this way, since the position of the shipwreck center point P _R can be defined on a plane orthogonal to the rotation axis 3, the axial position is defined next.

FIG. 4 shows the airfoil center point at an arbitrary radius R with respect to the radial trajectory Pn'-P _R '-Pt' from the boss airfoil center point Pb 'in FIG. 3 to the outer peripheral airfoil center point Pt'. Pr is _plotted on the plane OX plane, the radial distribution of the center line of the shipboard line P _{R, which} is projected by the radius _R , and the cross section at the same position of the blade 1. In the figure, 9 is the centrifugal force at the time of impeller rotation, 9a and 9b are the pressure-sensitive normal component and tangential component of each part of the centrifugal force 9, and arrow A indicates the inflow direction of the gas.

Here, a planar Sc plane orthogonal to the rotation axis 3 is considered, passing through the chord line center point Pb of the blade 1 in the outer peripheral portion of the boss 2.

라고 하면

로 된다. 따라서 Ls 또는

를 규정하여 반경 R을 부여하므로서 익현선중심점 P_R의 축방향위치를 정의할 수가 있다.When the center of the ship line at an arbitrary radius R is P _R , the distance between the Sc plane and the P _R point is Ls, and the angle between the boss part ship center point Pb and the Sc plane is

Say

It becomes Thus Ls or

By specifying the radius R to define the axial position of the ship center point P _R.

In order to construct an impeller, the blade line center point P _R may be a relative origin, and a wing section given by a camber may be formed thereon, and the entire wing surface may be a smooth curved surface. FIG. 5 shows a developed view when the blade 1 is cut from the cylindrical surface of radius R when the wing surface is formed with the ship center line P _R as the relative origin, and the cross section is developed in a two-dimensional plane. Since the camber wire 5 of the blade uses a circular arc in this embodiment, the center angle θ, the radius of the circular arc (P _R ), the leading edge of the blade (1b), and the trailing edge (1c) are used to form the circular arc. Shall be.

로 하고 이때

는 날개끝에서의 캠버각, 즉 날개끝에서의 캠버선의 중심각,

는 날개보스부에서의 캠버각, 즉 날개보스부에서의 캠버선의 중심각을 부여하고

=20°-30°,

=27°-37°,

<

로 한다. 날개를 붙이는 위치는 익현선

와 회전축(3)과 평행한 직선(6)간의 각도를 엇갈림각

로 하고,

를 반경방향으로 분포되도록 결정한다.In this embodiment, the radial distribution of θ

At this time

Is the camber angle at the tip of the wing, that is, the center angle of the camber line at the tip of the wing,

Denotes the camber angle at the wing boss, that is, the center angle of the camber line at the wing boss.

= 20 ° -30 °,

= 27 ° -37 °,

<

Shall be. Wing position is winged

And the angle between the straight line (6) parallel to the axis of rotation (3)

With

Determine to distribute radially.

의 반경반향분포를

로 하여 이때

는 날개끝에서의 엇갈림각,

는 날개 보스부에서의 엇갈림각으로 하고

=62°-72°,

=53°-63°,

>

로 하고 있다.In other words

Radial distribution of

At this time

Is the cross angle at the tip of the wing,

Is the cross angle at the wing boss

= 62 ° -72 °,

= 53 ° -63 °,

>

I am doing it.

L is the length of the chord, and is a parameter called T / L using the circumferential distance T between the wings shown in FIG. 6 to define the size of the blade in the radial direction.

As described above, an ultra-low noise axial impeller is obtained by setting the five parameters as independent values.

If the fan is to be quiet, the simplest method is to lower the speed of the fan to lower the airflow. However, this method reduces the sound, but greatly reduces the basic function of the fan.

In other words, the air volume decreases, so that a static pressure increase cannot be obtained. Here, the flow pattern of the impeller (radial distribution of the swirling velocity component of the airflow) is defined as a free vortex (Cu × R = constant, Cu: swirling velocity component of the airflow, R: radius, and radial direction of the airflow. The angular momentum constantly works from the boss to the outer periphery of the blade, in which case the radial distribution of the streamline is approximately constant from the inlet to the outlet. It is a flow pattern of forced vortex (Cu = Rx constant, rotational velocity component of Cu air flow, R: radius, and angular momentum of air flow increases in proportion to the radius). I was trying to lower the noise. However, the air flowing into the wing surface has a potential flow without vortex as long as the flow pattern is not forced from the outside.

Therefore, even though the impeller wing is forced vortex, the flow before flowing into the wing flows into the free vortex (the axial flow velocity of the flow is constant at each radial position of the impeller). Near the ferro boss, as shown in FIG. 7, the relative inlet angle ε becomes large.

Since the collision-free inflow angle to the wing 1 is γ, the tendency of ε> γ is strong, so that the flow 7 entering the impeller causes detachment at the pressure surface 5b of the wing and the peeling zone 8 increases. This increases the continuous frequency noise generated by the blades.

This tendency is prominent near the open point with a lot of airflow. That is, as the amount of air increases, the relative inflow angle ε gradually increases and the peeling region 8 increases.

을 줄여가면, 정압이 발생된 경우 반대로 받음각(sttack angle) α가 지나치게 커져서 부압면(5a)에서의 박리가 생겨 날개는 실속(失速)한다.Thus the wing angle of the wing to lower the noise near the opening point

When the pressure decreases, on the contrary, when the stacking angle α is excessively large, peeling occurs on the negative pressure surface 5a, causing the blade to stall.

Here, it is necessary to optimize the leading edge shape of the wing to lower the noise near the opening point and lower the noise when the static pressure is generated.

In the present invention, in order to obtain the above characteristics, the three-dimensional distribution of the center of the shipwreck is defined and the overall shape of the impeller is determined.

Here, the value of the parameter which determines the basic wing shape in this invention is shown next.

(반경방향일정)

(Radial schedule)

T / L = 1.05 (radius constant)

(Rt: Wing Tip Radius, Rb: Wing Boss Radius)

의 반경반향분포를 반경 R에 대하여 선형으로 하고 있으므로, 제3도에 있어서의 익현 선중심점 P_R'에 잇어서의 익현선중심점 궤적 Pb'- P_R'-Rt'의 접손과 반경 R이 이루는 각도 Pθ'는 보스부에서 날개선단을 향함에 따라 급격히 그 각도가 증대한다.In the basic wing

Since the radial distribution of is linear with respect to the radius R, the angle between the fold and the radius R of the chord center point trajectory Pb'- P _R '-Rt' following the chord center point P _R 'in FIG. The angle Pθ 'is rapidly increased as the tip of the boss moves toward the tip of the blade.

가 되도록 배치함으로써 날개 전연부에서의 흐름에 대하여 날개의 실질적인 캠버선의 형상은(5c)처럼 캠버가θ가 적어진 상태가 된다.Add here the center of the pimple line P _R

By arranging so as to be, the shape of the actual camber wire of the blade with respect to the flow at the blade leading edge becomes a state in which the camber is small as (5c).

In other words, in the flow flowing into the blade leading edge, the streamline shape substantially on the wing has a centrifugal force acting on the fluid due to the rotation of the blade, so that it is not a behavior flowing in the orthogonal direction in the radial direction. Since it flows in the form as shown in (7), the blade leading edge and the position of the streamline at the point where the wing surface is slightly entered are not changed excessively in the axial direction.

In such a streamlined form, it is possible to achieve a state in which the inflowing flow 7 of the blades flows into a collision-free state, that is, ε ≒ Υ, and the peeling region 8 at the pressure side disappears and noise is generated very much. Becomes smaller.

와

의 조합은 기본형의 것이 가장 좋지만, 팬을 설계함에 있어서 축방향치수의 제한 등에 의하여 이 값을 변경하여 쓰지 않으면 안되는 경우도 있다.

Wow

The combination of is best of the basic type, but in designing the fan, this value may need to be changed due to the limitation of the axial dimension.

Therefore, experimentally, the meter was set to the optimum value for each, and the experiments were made with several wings with different values, and the results were as shown in FIG. 8 and FIG.

의 값은 12.5°-32.5°사이에 있으면 최소비소음레벨 ks의 값은 충분히 적으며, 매우 저소음이다. 여기서 비소음레벨 ks(폰)은 다음식과 같이 정의한다.As you know from Figure 8

When the value of is between 12.5 ° and 32.5 °, the minimum specific noise level ks is small enough and very low noise. The non-noise level ks (phone) is defined as follows.

Ks = SPL-10 × Log (Q Ps2.5)

SPL = noise level (phone) Q = flow rate (㎥ / min)

Ps = static pressure (mmAq)

가 커지면 커질수록 소음레벨은 저하하고 있지만

=32.5°이상에서의 그 저하도가 포화해 있으며 강도면에서보아도

의 최대치는 32.5°이다.If you look only at the noise level

The bigger the, the lower the noise level.

The degree of degradation above = 32.5 ° is saturated,

The maximum value of is 32.5 °.

의 값에 의한 비소음레벨의 변화와 개방점에서의 소음레벨의 변화를 나타내고 있다.In Figure 9

The change in the non-noise level and the noise level at the open point are shown by the value of.

>40°의 조건을 충족시키면 소음레벨은 매우 저하한다.As you know from the drawings

When the condition of> 40 ° is met, the noise level is very low.

은 큰쪽이 소음은 저하하는 경향에 있지만, 굴곡강도의 점에서 보아 최대 50°정도가 한계이다.Practically

The larger the tends to lower the noise, the maximum is about 50 ° in terms of flexural strength.

=40°∼50°사이에 값이 존재하면 소음은 충분히 낮출 수가 있다.therefore

If the value is between 40 ° and 50 °, the noise can be lowered sufficiently.

과

에 반경방향으로 분포되도록 하였으므로 날개면이 전체적으로 흡입축에 기우는 부분이 많아지고, 그 때문에 날개면 위를 원호위의 궤적을 그리면서 통과해가는 익간의 흐름에 의하여 원심력이 날개 부압면에 크게 작용한다.In order to optimize the leading edge phenomenon,

and

Since the wing surface is distributed to the suction shaft as a whole, the centrifugal force acts largely on the wing negative pressure surface by the flow of vanes passing on the wing surface while drawing the trajectory of the arc. do.

That is, in FIG. 4, the negative pressure surface side normal component 9a of the centrifugal force 9 becomes a large compressive force with respect to the velocity boundary layer which develops on the sub-rock surface 5a, and can make a boundary layer very thin.

Since aerodynamic noise generated on the negative pressure surface 5a side is linearly proportional to the thickness of the boundary layer, the fact that the boundary layer can be made thinner reduces noise generated.

In addition, since the extrusion force acts on the boundary layer such as the negative pressure side component normal force 9a, a strong restraint action is generated against the separation of the boundary layer on the negative pressure surface 5a due to the increase in the angle of attack of the wing in the low wind volume region. (I) not to make it possible to obtain a wider operating range.

의 분포에 관하여 풀이한다.Next, the camber angle θ and stagger angle, one of the functional elements of the wing

Solve for the distribution of.

The camber angle θ is an important amount for determining the amount of work done by the wing element in the case of an arc-shaped impeller.

In general, the larger the θ, the more the blades work at the same rotation. However, the larger the θ, the more the noise tends to increase. Thus, all other parameters were of the basic type, and noise was measured on several wings which changed the distribution method of θ, and thus obtained 10 degrees.

In other words,

로 하여 실험을 하면, 비소음레벨은

의 곳에서 충분히 적어지고, 매우 저소음의 날개가 됨을 알 수가 있다.In the distribution equation,

If you experiment with, the noise level is

It becomes small enough in the place, and it turns out that it becomes the wing of very low noise.

의 값을 27°∼37°로까지 변화시켜도 이 경향은 변하지 않은 것을 부기하여둔다. 날개의 엇갈림 각

의 분포에 관하여도 상기한 바와 같이

와

를 최적화하고, 날개전연부에서의 플로우패턴을 자유와류에 가까운 것으로 하고 있으므로, 상대적 유입각ε에 관하여, 날개의 엇갈림각

도 강한 영향을 준다.The city is not doing

It is noted that this tendency did not change even if the value of? Was changed to 27 ° to 37 °. Wing cross angle

As described above with respect to the distribution of

Wow

And the flow pattern at the leading edge of the wing is close to the free vortex, so the blade shift angle with respect to the relative inflow angle ε

Also has a strong impact.

의 분포시키는 방법을The staggered angle of the wing here

How to distribute

By measuring the noise of several wings with all other parameters as the basic shape, the same result can be obtained from FIG.

=62°∼72°또한

, 즉

=53°∼63°로 하면 매우 저소음의 팬을 얻을 수 있음이 명확하다.As you know from the drawing

= 62 ° to 72 °

, In other words

It is clear that a fan with very low noise can be obtained by setting it to 53 degrees-63 degrees.

In the present invention, the pitch suspension ratio T / L = 1.05. In other words, the longer the length L of the blade with respect to the same amount, the smaller the camber angle θ, so that the noise decreases.

However, T / L = 1.0 is the limit when forming a wing using a press or the like on a single plate, and even in the case of plastic molding, this value is a limit in the relationship between molds.

On the other hand, increasing T / L causes noise to increase as described above.

Therefore, the maximum value of T / L is the limit value of T / L = 1.2, in which noise increases by about two phons.

In terms of the radial T / L distribution, it is better to make it almost constant in the radial direction in order to make the edge of the wing surface as special shape as before, and especially increasing the T / L at the outer periphery causes an increase in noise. do.

In terms of strength, the axial flow impeller according to the present invention basically has a structure in which the blade center point is arranged on the surface of the cone, and the method of distributing the camber angle θ is 24.5 ° at the outer circumference and 32 ° at the boss. Has a curved shape curved in the radial direction, and the flexural strength is much higher than that of a conventional planar blade.

Therefore, since the blade may be formed by a plate of about 2 mm even for a blade that has not been used with a plate having a thickness of 3 mm or more, the material cost can be greatly reduced.

In addition, since the blade thickness can be made thinner, the weight of the fan can be reduced, thereby reducing the load on the motor and driving the motor with a smaller output, thereby saving energy. In addition, since the boundary layer of the pressure side of the wing portion is designed to be strongly compressed, the secondary flow generated on the wing surface is also suppressed, which also increases the efficiency.

In addition, in the present embodiment, the number of the number of wings is about three, but if the necessary parameters are set as described above, the same effect is obtained regardless of the number of wings.

In addition, when the wing is used as a fan of lower noise, the combination with a bell mouth becomes important. Here, a systematic test with a systematic bell mouse was performed to form a bell mouse shape that was very low in noise level near the opening point. In order to reduce the noise level, it is necessary to reduce the relative speed with respect to the wing of the flow flowing into the wing surface as much as possible.

In other words, the flow of suction to the wings needs to be shaped to flow in the outer peripheral part of the wings.

12 is a view showing the relative positional relationship between the bell mouse and the impeller used in the present invention, (10) is the bell mouse body (10a) is the suction plane of the bell mouse 10 orthogonal to the rotation axis (3), (10b) ) Is the R portion of the bell mouse (10), (7) is the air flow.

Here, the basic bell mouse shape of the type that lowers the noise level near the opening point is indicated.

BR = 0.75DT

DB = 1.017DT

ℓx = 0

Where DT is the diameter of the impeller, BR is the size of the R portion of the bell mouse 10, DB is the inner diameter of the bell mouse 10, and lx is the distance between the end of the bell mouse 10 and the rear end of the outer periphery of the wing 1. .

Since the wing 1 has a large volume of the protruding portion protruding to the suction side, and is larger than the outer periphery of the wing 1, moreover, the leading edge 1b has a free vortex characteristic. There is a need for a bell mouse shape that reduces noise near the open point.

Since the bell mouse 10 according to the present invention has a suction plane 10a so as not to generate turbulence as much as possible in the flow of suction, the flow of suction is a flow of air to the wings 1 along the plane 10a. Inflow as (7).

Since the conventional bell mouse 10 has no suction plane 10a, the flow is separated at the tip of the bell mouse 10 and turbulence flows into the impeller. In the case of the bell mouse 10 of the present invention, since there is no peeling at the tip, noise generation due to abnormal lift variation of the wing due to suction turbulence is generally very small.

Since the bell mouse has a simple R shape having no straight duct, the air flow around the blade 1 flows into the blade 1 without being injured.

The flow rate of the air flowing in the leading edge of the wing decreases and the relative inflow angle ε with respect to the wing 1 decreases because the flow flowing into the wing 1 from the outer circumference of the wing 1 increases thereon. . Therefore, although the flow flowing from the leading edge of the wing has a high flow rate, the rate of inflow to the collision of the wing 1 increases and the pressure surface side peeling of the leading edge of the wing, which is the main cause of the noise generation near the opening point, is prevented. It cannot be suppressed and the noise level is drastically reduced.

When one bell mouse and a wing are used in combination, the basic bell mouse shape may have to be changed due to dimensional constraints or grille, so the characteristics of the bell mouse R were changed. .

In addition, all other shapes were made into the basic shape.

FIG. 13 is a characteristic diagram showing the values of the open point noise level for R and size BR of the bell mouse 10. If BR = 0.05DT to 0.2DT, an axial fan having a sufficiently low noise level can be provided. With regard to the inner diameter DB of the bell mouse, the closer to the outer diameter DT of the impeller, the closer the outer diameter DT of the impeller to the inner diameter DB, the wider the effective operating range. However, DB = 1.01DT is limited in terms of manufacturability.

In the axial fan of type that reduces open point noise, the noise level tends not to change too much at the open point even if the DB is slightly larger.

Therefore, a value of DB = 1.05DT was obtained as a marginal dimension method that satisfies surging characteristics and can sufficiently reduce the open point noise. Although not shown in the city, the surge limit in this case is 95% of the open quantity. In addition, the distance between the end of the bell mouse 10 and the trailing edge distance lx of the outer edge of the blade 1 should be basically lx = 0. However, since the trailing edge position at the boss is more protruding toward the blowing side than the position at the outer circumference, the axial fan is sufficiently low that the open point noise level is sufficiently low even if Lx is increased up to Lx = 0.04DT.

,

를 최적화한 축류날개를 써서 벨마우스 형상도 최적화 하였으므로 대풍량이며, 더우기 개방점 가까이에서의 소음레벨이 매우 낮은 축류팬을 제공할 수가 있다.According to the present invention mentioned above is an essential parameter of the wing

,

It is also possible to provide an axial fan with very high airflow and very low noise level near the opening point.

를 최적화함으로서 상기효과를 더욱 조장한 축류팬을 제공할 수 있다.In addition, the present invention is θ,

By optimizing the axial fan can be provided to further enhance the above effects.

Claims (2)

The axis of rotation passes through the center of the ship line P _R at the cross section when cutting the impeller at the cylindrical surface of the change R centered on the axis of rotation, and the center of the ship line Pb at the cross section when the boss portion of the blade is cut at the cylindrical surface of the radius Pb. When the distance between the plane Sc and the plane Sc is orthogonal to Ls, the point P _R is always positioned in the forward direction with respect to the plane Sc in the coordinate system in which the intake side of the air flow is in the forward direction.

Represented by

The value of

In the projection surface at the time of projecting the wing surface to the plane orthogonal to the axis of rotation, the boss portion of the blade is the center of the leading line Pb 'at the cross section at the time of cutting from the cylindrical surface of radius Rb, and the rotation axis is referred to as zero point of zero. In the coordinate system where the straight line connecting the point and the Pb 'point is the X axis, the center point of the leading line when cutting the wing surface from the cylindrical surface of the spot R is P _R ', and the angle formed between the straight lines P _R '-0 and the X axis is determined.

When

Radial distribution of

(Rt: wing tip radius, Rb: wing boss radius,

: The angle between the straight line Pt'-0 and the X-axis)

With In the suction bell mouse having a plane orthogonal to the axis of rotation and radiused from it to a curved surface of radius BR, the fan position is determined by the distance between the trailing edge and the bell mouse end at the outer periphery of the blade. When setting ℓx, the value of the size of each parameter BR = 0.15DT to 0.2DT DB = 1.01DT to 1.05DT ℓx = 0 to 0.04DT An axial flow fan characterized by the above-mentioned. The axis of rotation passes through the center of the ship line R _R at the cross section when cutting the impeller at the cylindrical surface of radius R about the axis of rotation, and the center of the ship line Rb at the cross section when the boss portion of the blade is cut at the cylinder surface of radius Rb. and to stay located in the forward direction with respect to R _R point in the suction side of the air flow when the perpendicular distance between the plane Sc which Ls the coordinates in the normal direction to the plane Sc

Represented by

The value of

In the projection surface at the time of projecting a wing surface to the plane orthogonal to a rotation axis, the boss | hub part of the said blade is made into the tip line center point Pb 'in the cross section at the time of cutting | disconnection from the cylindrical surface of radius Rb, and the said rotation axis is origin 0 In the coordinate system where the straight line connecting the 0 point and the Rb 'point is the X axis, the center point of the leading line when cutting the wing surface from the cylindrical surface of radius R is P _R ' and the straight lines P _R '-0 and the X axis are Angle

When

Radial distribution of

(Rt: wing tip radius, Rb: wing boss radius, Set: angle between the straight line Pt'-0 and the X axis)

In the developed view in which the wing surface is cut from the cylindrical surface of radius R and its cross section is developed into a secondary circular surface, the shape of the camber line at the wing end surface is arc-shaped, and the center angle for forming the arc is? The radial distribution of θ

(

= Camber angle at wing tip,

: Wing boss part to camber angle)

,

,

In the developed view, the angle formed by the straight line passing through the leading edge of the blade parallel to the blade line and the rotation axis of the blade

When

Radial distribution of

(

: Staggered angle at the tip of the wing,

: The cornering angle at the wing boss)

In the suction bell mouse having a plane orthogonal to the rotation axis and narrowed therefrom to a curved surface of radius BR, and having an inner diameter DB with respect to the wing outer diameter DT, the fan position is the trailing edge of the wing outer circumference and the bell mouse end. When the sub-interval is set to ℓx, the value of the size of each parameter BR = 0.05DT to 0.2DT DB = 1.01DT to 1.05DT ℓx = 0 to 0.04DT An axial flow fan characterized by the above-mentioned.

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