Centrifugal fan blades, centrifugal fans and air conditioners

Abstract

This disclosure relates to a centrifugal fan blade, a centrifugal fan, and an air conditioner. The centrifugal fan blade includes blades, each blade having a leading edge, a pressure surface, a trailing edge, and a suction surface connected sequentially. The blade has a blade center profile, designed such that the pressure surface profile of the pressure surface and the suction surface profile of the suction surface are arranged with equal thickness on both sides of the blade center profile, thereby equally dividing the blade thickness. Both the blade center profile and the profile of the blade thickness are spline curves. The curve control equation for the blade center profile is: 10 3 y = -0.318s 2 x 3 -33.839sx 2 +867.23x+48.511s ‑1 The curve governing equation for the blade thickness is: 10 3 d = -0.083s 2 x 3 -9.214sx 2 +95.145x +3967.2s ‑1 Where 0≤x≤b, 0.7≤s≤1.3, b is the blade chord length, s is the modulation correction parameter, d is the blade thickness, the x-axis is the direction extending along the blade chord length, the y-axis is the direction perpendicular to the blade chord length, and the origin of the coordinate system is the center O of the inscribed circle of the leading edge of the blade.

Description

Technical Field

[0001] This invention relates to the field of air conditioning technology, specifically to a centrifugal fan blade, a centrifugal fan, and an air conditioner. Background Technology

[0002] With the widespread use of air conditioners, users have placed higher demands on their performance, especially in terms of low power consumption and low noise. Multi-blade centrifugal fans, due to their compact structure, low noise, and high static pressure, are widely used in ducted air conditioners, floor-standing units, and other air conditioning models.

[0003] The blade design plays a crucial role in the performance of centrifugal fans. Small structural features on the blades, based on fluid dynamics principles, can further improve fan performance. Existing multi-blade centrifugal fan blades typically employ an airfoil design, which includes a pressure surface, suction surface, leading edge, and trailing edge, with profiles often being circular arcs or splines. Existing centrifugal fan blades generally use spline profiles designed primarily for the pressure and suction surfaces. Existing centrifugal fan blades suffer from high blade boundary layer drag, high fan operating power, and high noise levels.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] To address the aforementioned technical issues and further improve the performance of centrifugal fans, this patent proposes a high-efficiency, low-noise centrifugal fan blade designed with the blade midline and blade thickness as spline profiles. This centrifugal fan blade and the centrifugal fan system it belongs to significantly reduce the fan's operating power and noise radiation levels.

[0006] According to one aspect of the present invention, a centrifugal fan blade is provided, the centrifugal fan blade comprising blades, the blades being provided with a leading edge, a pressure surface, a trailing edge, and a suction surface connected sequentially end to end, characterized in that the blades are provided with a blade center profile, the blade center profile being designed such that the pressure surface profile of the pressure surface and the suction surface profile of the suction surface are arranged with equal thickness on both sides of the blade center profile, thereby equally dividing the blade thickness, the blade center profile and the profile of the blade thickness are both spline curves, and the curve control equation of the blade center profile is: 10 3 y = -0.318s 2 x 3 -33.839sx 2 +867.23x+48.511s -1 The curve governing equation for the blade thickness is: 10 3 d = -0.083s 2 x 3 -9.214sx 2+95.145x +3967.2s -1 Where 0≤x≤b, 0.7≤s≤1.3, b is the blade chord length, s is the modulation correction parameter, d is the blade thickness, the x-axis is the direction extending along the blade chord length, the y-axis is the direction perpendicular to the blade chord length, and the origin of the coordinate system is the center O of the inscribed circle of the leading edge of the blade.

[0007] More preferably, the characteristic chord length of the blade The characteristic chord length at which the maximum curvature of the blade's midline is located is... Then it satisfies

[0008] More preferably, the blade is provided with a rear step, wherein the rear step is located near the position where the airflow angle of the pressure surface is the largest and the boundary layer of the suction surface is most easily separated.

[0009] More preferably, an inscribed circle with a diameter of d' is selected. The tangent points of this inscribed circle with the pressure surface and the suction surface are the first tangent point P' and the second tangent point S', respectively. The rear step includes a suction surface step profile and a pressure surface step profile. The outline of the suction surface step profile is formed by the line connecting the second tangent point S' and the center M' of the inscribed circle and the suction surface step profile. The outline of the pressure surface step profile is formed by the line connecting the first tangent point P' and the center M' of the inscribed circle and the pressure surface step profile. The distance from the second tangent point S' to the intersection of the line connecting the second tangent point S' and the center M' of the inscribed circle and the suction surface step profile is the penetration depth hs of the suction surface step profile. The distance from the first tangent point P' to the intersection of the line connecting the first tangent point P' and the center M' of the inscribed circle and the pressure surface step profile is the penetration depth hp of the pressure surface step profile. The characteristic chord length at the location of the center M' of the inscribed circle is... Where b' is the x-coordinate of the center M' of the inscribed circle in the X-axis direction, and the starting point of the suction surface step profile of the rear step is determined by the characteristic chord length. The starting point of the pressure surface step profile of the rear step is determined by the characteristic chord length and the cutting depth hs corresponding to the suction surface step profile. The cut-in depth hp corresponding to the pressure surface step profile is determined, and the endpoints of the suction surface step profile and the pressure surface step profile are tangent to the corresponding suction surface profile and pressure surface profile at the trailing edge of the blade.

[0010] More preferably, the characteristic chord length satisfy The cutting depth hp corresponding to the step profile of the pressure surface satisfies 0.1≤hp / d'≤0.2 and the cutting depth hs corresponding to the step profile of the suction surface satisfies 0.1≤hs / d'≤0.2.

[0011] According to another aspect of the present invention, a centrifugal fan is provided, the centrifugal fan comprising the aforementioned centrifugal fan blades.

[0012] According to another aspect of the present invention, an air conditioner is provided, the air conditioner including the centrifugal fan described above.

[0013] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0014] 1. The high-efficiency, low-noise centrifugal fan blades designed with the blade midline and blade thickness as spline profiles significantly reduce the fan's operating power and noise radiation level.

[0015] 2. The blades were modified by adding a rear step structure. This rear step generates stable internal vortices, which reduces the surface boundary layer drag and accelerates surface flow, thus improving the problem of high blade boundary layer drag and reducing the operating power of the wind turbine.

[0016] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0017] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0018] Figure 1 This is a schematic diagram of the structure of a basic blade-type centrifugal fan blade according to the first embodiment of the present invention.

[0019] Figure 2 yes Figure 1 The diagram shows the basic blade profile of a centrifugal fan.

[0020] Figure 3 This is a schematic diagram of the structure of a rear-mounted stepped-blade centrifugal fan blade according to a second embodiment of the present invention.

[0021] Figure 4 Figure 3 The diagram shows the profile of the stepped blade of a centrifugal fan.

[0022] Figure 5This is a schematic diagram showing the tangency of the tail edge of the profile.

[0023] Figure 6 Is adopted Figure 2 The centrifugal fan with the basic blade shape shown is a centrifugal fan and Figure 4 The diagram shows the power curves of a centrifugal fan with a rear-mounted stepped blade and an existing centrifugal fan at different air volumes.

[0024] Figure 7 Is adopted Figure 2 The diagram shows the noise curves of a centrifugal fan with a basic blade type and an existing centrifugal fan at different air volumes.

[0025] Wherein: 1-Blade base plate, 2-Multiple blades, 3-Impeller center plate, 4-Rear step, 5-Inscribed circle, 6-Pressure surface tangent point, 7-Suction surface tangent point, 21-Blade leading edge, 22-Pressure surface, 23-Blade trailing edge, 24-Suction surface, 221-Pressure surface profile, 241-Suction surface profile, 211-Blade leading edge profile, 231-Blade trailing edge profile, 251-Blade center profile, 2214-Pressure surface step profile, 2414-Suction surface step profile.

[0026] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0027] In the description of this invention, it should be noted that the terms "inner" and "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "contact," and "communication" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] This invention proposes a centrifugal fan blade. Figure 1 A schematic diagram of the structure of a basic blade-type centrifugal fan blade according to a first embodiment of the present invention is shown. Figure 1The centrifugal fan blade of this embodiment includes an integrally formed fan blade base plate 1, multiple blades 2, and an impeller disk 3. The fan blade base plate 1 is annular, and the multiple blades 2 are evenly arranged on the inner peripheral wall of the fan blade base plate 1 along the circumference of the fan blade base plate 1. The basic blade profile of the blades 1 extends axially along the axis of the impeller disk 3 and is evenly arranged circumferentially along the impeller disk 3.

[0030] Figure 2 It shows Figure 1 The diagram shows the basic blade profile of a centrifugal fan. Figure 2 As shown, the blade 2 is provided with a leading edge 21, a pressure surface 22, a trailing edge 23, and a suction surface 24 connected sequentially from end to end. The pressure surface profile 221 of the pressure surface 22 and the suction surface profile 241 of the suction surface 24 are both spline curves. The leading edge profile 211 of the leading edge 21 is an arc profile, and the trailing edge profile 231 of the trailing edge 23 is a straight line. The trailing edge 23 is connected to the blade base plate 1, and the leading edge 21 extends towards the axis of the blade base plate 1. The profile 221 of the pressure surface 22 is the curve presented by projecting the pressure surface 22 along the axis of the blade base plate 1. The profile 241 of the suction surface 24 is the curve presented by projecting the suction surface 24 along the axis of the blade base plate 1. The profile 211 of the blade leading edge 21 is the curve presented by projecting the blade leading edge 21 along the axis of the blade base plate 1. The profile 231 of the blade trailing edge 23 is the curve presented by projecting the blade trailing edge 23 along the axis of the blade base plate 1.

[0031] like Figure 2 As shown, the blade is provided with a blade centerline 251. This blade centerline 251 is designed to control the variation of the blade centerline and the diameter of the inscribed circle (i.e., the blade thickness), so that the profile 221 of the pressure surface 22 and the profile 241 of the suction surface of the blade 2 are arranged with equal thickness on both sides of the blade centerline 251, thus equally dividing the blade thickness d of the blade 2. Specifically, a coordinate system XOY is established with the center point O of the inscribed circle 5 of the blade leading edge 21 as the origin, the direction extending along the blade chord length b of the blade 2 as the X-axis, and the direction perpendicular to the blade chord length b as the Y-axis. Point M(x,y) is any point on the blade centerline, using a free spline profile design, with tangent points P and S on the pressure surface 22 and suction surface 24, respectively. The variation of the blade centerline 251 and the blade thickness d both satisfy a cubic polynomial equation. Specifically, the curve control equation of the blade centerline 251 is: 10 3 y = -0.318s 2 x 3 -33.839sx 2 +867.23x+48.511s -1 The curve governing equation for the blade thickness d is: 103 d = -0.083s 2 x 3 -9.214sx 2 +95.145x +3967.2s -1 Where 0≤x≤b, 0.7≤s≤1.3, b is the chord length, and s is the modulation correction parameter.

[0032] The blade 2 is designed according to the curve equation of the blade midline 251 and the curve equation of the blade thickness d, so as to obtain a high-efficiency and low-noise centrifugal fan blade with the blade midline 251 and the blade thickness d as the spline design objects.

[0033] As a further preferred embodiment, let the characteristic chord length of blade 2 be... The characteristic chord length at which the maximum curvature of the blade midline 251 is located is... Then it satisfies To meet the optimized flow drag reduction design.

[0034] Figure 3 A schematic diagram of the structure of a rear-mounted stepped-blade centrifugal fan blade according to a second embodiment of the present invention is shown. Figure 2 Based on the basic blade profile shown, the rear sections of the pressure surface 22 and suction surface 24 of blade 2 are modified by adding a rear-stepped structural feature. This rear-stepped blade profile centrifugal fan includes, in addition to... Figure 1 The basic blade centrifugal fan blade shown includes an integrally formed blade base plate 1, multiple blades 2, and impeller disk 3. It also includes a rear step 4, which is located near the position where the airflow angle of the pressure surface 22 is the largest and the boundary layer of the suction surface 24 is most easily separated. When the fan is running, the high-speed airflow will form a stable internal rotating vortex at the step position, replacing sliding friction with rolling friction, thereby reducing the boundary layer resistance of the blade surface and accelerating the surface airflow, thus reducing the operating power of the fan blade.

[0035] Specifically, Figure 4 It shows Figure 3 The diagram shows the profile of the stepped blade of a centrifugal fan. Figure 4 As shown, an inscribed circle with a diameter of d' is selected, and the center of this inscribed circle 5 is M'. The points of tangency between this inscribed circle 5 and the pressure surface 22 and the suction surface 24 are the first point of tangency P' and the second point of tangency S', respectively. The characteristic chord length at the position of the center M' of the inscribed circle is... The outline of the rear step 4 is formed by the line connecting the first tangent point P' or the second tangent point S' to the center M' of the inscribed circle, and the pressure surface step profile 2214 of the pressure surface 22 or the suction surface step profile 2414 of the suction surface 24. The starting points of the pressure surface step profile 2214 and the suction surface step profile 2414 of the rear step 4 are determined by the characteristic chord length. The depths of penetration are determined by the corresponding penetration depths hp (penetration depth of the pressure surface step profile 2214) and hs (penetration depth of the suction surface step profile 2414). The endpoints of the pressure surface step profile 2214 and the suction surface step profile 2414 of the rear step 4 are tangent to the profile 221 of the pressure surface 22 and the profile 241 of the suction surface 2 of the blade 2 at the trailing edge 23 (forming pressure surface tangency point 6 and suction surface tangency point 7 respectively), to ensure that the exit installation angles β1 and β2 of the blade 2 remain unchanged. Figure 5 As shown, taking the outlet installation angle β1 of the blade pressure surface as an example, it refers to the angle between the tangent of the pressure surface profile 221 of blade 2 at the trailing edge tangent point 6 and the opposite direction of the centrifugal fan blade's circumferential rotation. The characteristic chord length of blade 2... satisfy The penetration depth hp of the pressure surface step profile 2214 satisfies 0.1≤hp / d'≤0.2 and the penetration depth hs of the suction surface step profile 2414 satisfies 0.1≤hs / d'≤0.2.

[0036] The air conditioner of this invention adopts Figure 2 The basic blade profile shown is for wind turbine blades and Figure 4 The rear-mounted stepped blade profile shown in the image significantly reduces the operating power and noise level of the air conditioner's fan. Figure 6 The diagram shows the air volume-power curves of a wind turbine blade using the prior art, a wind turbine blade with a basic blade profile proposed according to the present invention, and a wind turbine blade blade with a rear stepped blade profile. Figure 7 The diagram illustrates airflow-noise profiles for wind turbine blades employing existing technology and those based on the blade profile proposed according to the present invention. Figure 6 As shown, curve 8 represents the airflow-power curve of the previous generation of fan blades, curve 9 represents the airflow-power curve of fan blades with a basic blade profile, and curve 10 represents the airflow-power curve of fan blades with a rear-mounted stepped blade profile. Under an external static pressure of 50 Pa and the required airflow at various speeds, the power is reduced by approximately 12%. Figure 7 As shown, curve 11 represents the airflow-noise curve of the previous generation of fan blades, and curve 12 represents the airflow-noise curve of the fan blade with the basic blade profile. Figure 7 As shown, using Figure 2 The fan blades with the basic blade profile shown reduce noise by no less than 2dB under an external static pressure of 50Pa and the required air volume at various speeds, significantly reducing the noise radiation level of the air conditioner.

[0037] The blade 2 of this invention can be used in different types of centrifugal fan blades, including double-suction impellers and single-suction impellers, and can be used in centrifugal fans of different types of air conditioning units, such as centrifugal fans for ducted air conditioners and centrifugal fans for vertical cabinet air conditioners. Furthermore, the profile of the blade's leading edge can also be an elliptical arc, a streamlined profile, a spindle-shaped profile, or a straight profile. The profile of the blade's trailing edge can also be a circular arc or an elliptical arc.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

[0039] Although the different examples have the specific components shown in the illustrations, the embodiments of this disclosure are not limited to these specific combinations. Some of the components or features in one example may be used in combination with features or components in another example.

[0040] Those skilled in the art will understand that the above embodiments are exemplary and not restrictive. That is, modifications of this disclosure will fall within the scope of the claims. Therefore, the following claims should be studied to determine their true scope and content.

Claims

1. A centrifugal fan blade, the centrifugal fan blade comprising blades, the blades being provided with a leading edge, a pressure surface, a trailing edge, and a suction surface connected sequentially end to end, characterized in that, The blade has a blade center profile, which is designed such that the pressure surface profile of the pressure surface and the suction surface profile of the suction surface are arranged with equal thickness on both sides of the blade center profile, thereby equally dividing the blade thickness. Both the blade center profile and the blade thickness profile are spline curves. The curve control equation for the blade center profile is: 10 3 y = -0.318s 2 x 3 -33.839sx 2 +867.23x+48.511s -1 The curve governing equation for the blade thickness is: 10 3 d = -0.083s 2 x 3 -9.214sx 2 +95.145x +3967.2s -1 Where 0≤x≤b, 0.7≤s≤1.3, b is the blade chord length, s is the modulation correction parameter, d is the blade thickness, the x-axis is the direction extending along the blade chord length, the y-axis is the direction perpendicular to the blade chord length, and the origin of the coordinate system is the center O of the inscribed circle of the leading edge of the blade.

2. The centrifugal fan blade according to claim 1, characterized in that, The characteristic chord length of the blade The characteristic chord length at which the maximum curvature of the blade's midline is located is... Then it satisfies 3. The centrifugal fan blade according to claim 1 or 2, characterized in that, The blade is provided with a rear step, wherein the rear step is located near the position where the airflow angle of the pressure surface is the largest and the boundary layer of the suction surface is most easily separated.

4. The centrifugal fan blade according to claim 3, characterized in that, An inscribed circle with diameter d' is selected. The points of tangency between this inscribed circle and the pressure surface and the suction surface are the first tangency point P' and the second tangency point S', respectively. The rear step includes a suction surface step profile and a pressure surface step profile. The outline of the suction surface step profile is formed by the line connecting the second tangency point S' and the center M' of the inscribed circle and the suction surface step profile. The outline of the pressure surface step profile is formed by the line connecting the first tangency point P' and the center M' of the inscribed circle and the pressure surface step profile. The distance from the second tangency point S' to the intersection of the line connecting the second tangency point S' and the center M' of the inscribed circle with the suction surface step profile is the penetration depth hs of the suction surface step profile. The distance from the first tangency point P' to the intersection of the line connecting the first tangency point P' and the center M' of the inscribed circle with the pressure surface step profile is the penetration depth hp of the pressure surface step profile. The characteristic chord length at the location of the center M' of the inscribed circle is... Where b' is the x-coordinate of the center M' of the inscribed circle in the X-axis direction, and the starting point of the suction surface step profile of the rear step is determined by the characteristic chord length. The starting point of the pressure surface step profile of the rear step is determined by the characteristic chord length and the cutting depth hs corresponding to the suction surface step profile. The cut-in depth hp corresponding to the pressure surface step profile is determined, and the endpoints of the suction surface step profile and the pressure surface step profile are tangent to the corresponding suction surface profile and pressure surface profile at the trailing edge of the blade.

5. The centrifugal fan blade according to claim 1 or 2, characterized in that, Characteristic string long satisfy The cutting depth hp corresponding to the step profile of the pressure surface satisfies 0.1≤hp / d'≤0.2 and the cutting depth hs corresponding to the step profile of the suction surface satisfies 0.1≤hs / d'≤0.

2.

6. A centrifugal fan, characterized in that, The centrifugal fan includes centrifugal fan blades according to any one of claims 1-5.

7. An air conditioner, characterized in that, The air conditioner includes the centrifugal fan according to claim 6.

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