阅读说明：本技术 一种多翼离心风机叶片 (Multi-wing centrifugal fan blade ) 是由 何立博 于 2018-06-25 设计创作，主要内容包括：本发明涉及一种多翼离心风机叶片,叶片型线包括有进口端曲线AB和出口端曲线BC,所述出口端曲线BC为圆弧曲线,所述进口端曲线AB为对数螺旋线,其特征在于：所述叶片型线的进口侧设有与进口端曲线AB相衔接的曲线PA,所述曲线PA为圆弧曲线,且该曲线PA的曲率K<Sub>1</Sub>大于出口端曲线BC的曲率K<Sub>2</Sub>。与现有技术相比,本发明的优点在于：通过增加大曲率的圆弧曲线,减小了叶片进口端的弧长,进而减小了叶片进口端的宽度,增加了进口端处气流流出的速度,使得进口端冲击降低,增加了抗回流效果；此外,进口端曲线AB采用对数螺旋线,由于对数螺旋线对偏转气流冲击小、分离少的特点,使得进口冲击进一步地降低,提升了整体流动效率。(The invention relates to a multi-wing centrifugal fan blade, wherein the blade profile comprises an inlet end curve AB and an outlet end curve BC, the outlet end curve BC is an arc curve, the inlet end curve AB is a logarithmic spiral line, and the multi-wing centrifugal fan blade is characterized in that: the inlet side of the blade molded line is provided with a curve PA connected with an inlet end curve AB, the curve PA is a circular arc curve, and the curvature K of the curve PA 1 Curvature K greater than outlet end curve BC 2 . Compared with the prior art, the invention has the advantages that: by increasing the arc curve with large curvature, the arc length of the inlet end of the blade is reduced, the width of the inlet end of the blade is further reduced, the outflow speed of airflow at the inlet end is increased, the impact of the inlet end is reduced, and the backflow resistance effect is increased; in addition, the inlet end curve AB adopts a logarithmic spiral, and due to the characteristics of small impact and less separation of the logarithmic spiral to deflection airflow, the inlet impact is further reduced, and the overall flow efficiency is improved.)

1. The utility model provides a multi-wing centrifugal fan blade, blade molded lines are including entrance point curve AB and exit end curve BC, exit end curve BC is the circular arc curve, entrance point curve AB is logarithmic spiral, its characterized in that: the inlet side of the blade molded line is provided with a curve PA connected with an inlet end curve AB, the curve PA is a circular arc curve, and the curvature K of the curve PA₁Is greater thanCurvature K of outlet end curve BC₂。

2. The multi-airfoil centrifugal fan blade of claim 1, wherein: radius r of the curve PA₁Is defined asCurvature K of curve PA₁＝1/r₁Central angle of said curve PA

3. The multi-airfoil centrifugal fan blade of claim 2, wherein: the polar radius R of the inlet end curve AB is defined as

4. The multi-airfoil centrifugal fan blade of claim 3, wherein: the total wrap angle alpha of the blade profile belongs to [70 degrees, 120 degrees ], and the angle variable theta of the polar coordinate AB of the inlet end curve belongs to [0 degree, 70 degrees ].

5. Multi-airfoil centrifugal fan blade according to any of claims 1 to 4, wherein: the width of the two end parts of the blade in the length direction is smaller than that of the middle part of the blade, the front end of the blade on one side of the air outlet is provided with a first inclined section which is gradually inclined towards the direction of the air outlet side from front to back, and the rear end of the blade on one side of the air outlet is provided with a second inclined section which is gradually inclined towards the direction of the air outlet side from back to front.

6. The multi-airfoil centrifugal fan blade of claim 5, wherein: the projection length m of the first inclined section in the length direction of the blade is defined as

7. The multi-airfoil centrifugal fan blade of claim 6, wherein: the included angle between the first inclined section and the length direction of the blade is delta, the included angle between the second inclined section and the length direction of the blade is epsilon, delta is more than or equal to 2 degrees and less than or equal to 15 degrees, and epsilon is more than or equal to 2 degrees and less than or equal to 15 degrees.

8. The multi-airfoil centrifugal fan blade of claim 1, wherein: and a straight line section CD connected with the outlet end curve BC is arranged on the outlet side of the blade molded line.

9. The multi-airfoil centrifugal fan blade of claim 8, wherein: the straight line segment CD is tangent to the outlet end curve BC.

10. The multi-airfoil centrifugal fan blade of claim 1, wherein: the blade is provided with a blade mounting part.

Technical Field

The invention relates to a centrifugal fan, in particular to a multi-wing centrifugal fan blade.

Background

Centrifugal fans have been widely introduced into range hoods due to their advantages of large suction, low noise, compact structure, etc. The blades of the impeller of the existing multi-wing centrifugal fan mainly adopt a single arc-shaped line structure, and the impact of inlet airflow is large, so that the efficiency of the fan is reduced, and the noise is increased. At present, there is a fan structure for improving fan performance by changing blade profile, such as "a low noise range hood impeller volute system" disclosed in chinese patent application with application number 201510270958.7 (application publication number CN 104929983 a), which discloses that an air inlet end of a blade is arranged around the center of an impeller and forms an inner arc track, an air outlet end of the blade is arranged around the center of the impeller and forms an outer arc track, an α angle is formed between an outer arc tangent of the air inlet end and a tangent of the inner arc track, and 60 ° < α < 90 °, a β angle is formed between an outer arc tangent of the air outlet end and a tangent of the outer arc track, and 150 ° < β < 170 °. Although the volute system can reduce airflow impact and energy loss through designing reasonable alpha and beta angles, so that the performance of the fan can be improved, the volute only discloses the angle sizes of the air inlet end and the air outlet end, and the specific structure of the blade profile is not described.

If the applicant previously applied chinese utility model patent No. CN201720787391.5 (No. CN206957981U), the inlet curve AB of the blade profile of this multi-blade centrifugal fan blade is a logarithmic spiral, the outlet curve BC of the blade profile is an arc, that is, the logarithmic spiral replaces the arc of the existing inlet, and the logarithmic spiral reduces the inlet impact by the characteristics of small impact and less separation of the logarithmic spiral on the deflected airflow, but the total arc length of the blade profile is relatively long, and the backflow is relatively large.

In summary, there is a need for further improvement of the existing centrifugal fan blade structure.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide a multi-blade centrifugal fan blade which reduces the total arc length of the blade profile by reducing the arc length of the inlet section, thereby reducing the inlet impact.

The second technical problem to be solved by the present invention is to provide a multi-blade centrifugal fan blade that reduces the width of the inlet and improves the air output, in view of the current situation of the prior art.

The technical scheme adopted by the invention for solving the first technical problem is as follows: the utility model provides a multi-wing centrifugal fan blade, blade molded lines are including entrance point curve AB and exit end curve BC, exit end curve BC is the circular arc curve, entrance point curve AB is logarithmic spiral, its characterized in that: the inlet side of the blade molded line is provided with a curve PA connected with an inlet end curve AB, the curve PA is a circular arc curve, and the curvature K of the curve PA₁Curvature K greater than outlet end curve BC₂。

In order to reduce the backflow while facilitating the control of the variation of the radius of the curve PA, the radius r of said curve PA₁Is defined as

Curvature K of curve PA₁＝1/r₁Central angle of said curve PA

Wherein r is₁＜R₁，K₂＝1/R₁，R₁The radius corresponding to the point B of the blade profile. Therefore, because the air flow speed at the inlet end is low and the backflow is large, the backflow with large resistance is reduced by increasing the arc with large curvature at the inlet end, and the static pressure under severe working conditions is improved; meanwhile, by adopting the fraction and the square relation of the two parameters p and q, the change of the radius can be more conveniently controlled.

Further preferably, the polar radius R of the inlet end curve AB is defined as

Variable helical expansion angleλ₁And λ₂∈[2°,8°]，∈[30，70]，Is the wrap angle of the curve AB at the inlet end, and the adjusting term s is E [ -0.5, 0.5 [ ]]，r∈[-5，5]And r ≠ 1, s is an adjustment coefficient

θ₀Is the initial angle of the point B of the inlet curve AB, and theta is the polar coordinate angle variable of any point on the inlet curve AB. Therefore, the characteristics of small impact and less separation of the logarithmic spiral line on the deflection airflow are utilized to reduce the impact of the inlet and improve the overall flow efficiency.

Further preferably, the total wrap angle alpha epsilon [70 degrees ], 120 degrees ] of the blade profile line, and the angle variable theta epsilon [0 degree ], 70 degrees of the polar coordinate of the inlet end curve AB.

The technical scheme adopted by the invention for solving the second technical problem is as follows: the width of the two end parts of the blade in the length direction is smaller than that of the middle part of the blade, the front end of the blade on one side of the air outlet is provided with a first inclined section which is gradually inclined towards the direction of the air outlet side from front to back, and the rear end of the blade on one side of the air outlet is provided with a second inclined section which is gradually inclined towards the direction of the air outlet side from back to front.

In order to reduce backflow, the projection length m of the first inclined section in the length direction of the blade is defined as

The projection length n of the second inclined section in the length direction of the blade is defined as n ═

Where L is the total blade length. Because the air flow speed of the middle area of the blade is high, the air inflow is large, and the impact is large, the natural deflection of the angle of the air flow inlet in the axial direction caused by the prerotation of the inlet side of the air flow can be better adapted through arranging the relatively long inclined sections at the two ends of the air outlet side of the blade, and the large impact of the middle area of the blade is better adapted, so that the backflow under large resistance is reduced.

In order to reduce the impact and the congestion when the airflow is converted from the axial direction to the radial direction, the included angle between the first inclined section and the length direction of the blade is delta, the included angle between the second inclined section and the length direction of the blade is epsilon, delta is more than or equal to 2 degrees and less than or equal to 15 degrees, and epsilon is more than or equal to 2 degrees and less than or equal to 15 degrees.

In order to increase the pressure on the outlet side, a straight line segment CD connected with the outlet end curve BC is arranged on the outlet side of the blade profile.

For better outlet-side flow improvement, the straight line segment CD is tangent to the outlet end curve BC.

In order to facilitate the installation of the blade, a blade installation part is arranged on the blade.

Compared with the prior art, the invention has the advantages that: the blade profile of the multi-wing centrifugal fan blade is provided with an arc curve PA connected with an inlet end curve AB at the inlet side, and the curvature K of the arc curve PA₁Curvature K greater than outlet end curve BC₂The arc length of the inlet end of the blade is reduced by increasing the arc curve with large curvature, so that the width of the inlet end of the blade is reduced, and meanwhile, the area of an air outlet of the blade is increased, so that the air output and the speed of airflow flowing out of the air outlet at the inlet end are increased, the impact of the inlet end is reduced, and the backflow resistance effect is increased; in addition, the inlet end curve AB adopts a logarithmic spiral line, and because the logarithmic spiral line has the characteristics of small impact on deflection airflow and less separation, the inlet impact is further reduced, and the overall flow efficiency is improved; in addition, the design of the inclined sections of the two end edges of the blades on one side of the air outlet better adapts to the large impact of the middle area of the blades, and meanwhile, the impact and the congestion of the air flow converted from the axial direction to the radial direction are reduced, so that the overall flow is more uniform and stable, and the overall flow efficiency is improved.

Drawings

FIG. 1 is a schematic structural diagram of an impeller according to an embodiment of the present invention;

FIG. 2 is a schematic view of a blade profile according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a blade according to a first embodiment of the present invention;

fig. 4 is a graph showing a variation of the flow velocity of the air flow in the impeller along the axial direction according to the first embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an impeller according to a second embodiment of the present invention;

fig. 6 is a schematic structural diagram of a blade profile according to a second embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.