Flow guide folding wing type corrugated blade surface axial flow cooling fan

Abstract

The utility model relates to a flow guide folding wing type corrugated blade surface axial flow cooling fan, which aims at solving the technical problems that the air flow speed at the suction surface of a fan blade is slow, the stall risk is high and the induced resistance is high because the conventional similar products rarely adopt the structural design of combining a folding wing type fan blade and a corrugated fan blade. The impeller of the axial flow cooling fan comprises a hub and fan blades, wherein the fan blades are spirally, obliquely and equidistantly arranged on the outer diameter of the hub; the fan blade is characterized in that corrugated strip-shaped protrusions which are arranged at equal intervals are arranged on the smooth transition curved surfaces of the upper wing surfaces of the tops of the fan blades respectively, and the strip-shaped protrusions are arranged at the highest point in the middle and the lowest points on the two sides respectively; the strip-shaped protrusions at the front edges of the fan blades slowly protrude from the lowest points of the two sides to 25% of the chord length b to the highest point, the 7% of the chord length b at the rear edges of the fan blades slowly and neatly gather, and the upper wing faces of the bottoms of the fan blades are smooth transition planes. And the top upper wing surface and the bottom lower wing surface of the fan blade are respectively provided with a folding wing edge.

Description

Technical Field

[0001] This utility model relates to a cooling fan, specifically a flow-guiding, corrugated-blade axial flow cooling fan. Background Technology

[0002] Cooling fans generally refer to fans used for cooling motherboard devices such as CPUs and graphics cards. Their main purpose is to conduct heat away and blow it into the surrounding air to achieve a cooling effect. The core component is the impeller, with equidistant blades on the outer diameter of the impeller hub. According to Bernoulli's principle: gases are incompressible; as flow velocity increases, the static pressure of the fluid decreases; conversely, as flow velocity decreases, the static pressure of the fluid increases. When an axial cooling fan rotates, the flow velocity is higher and the pressure is lower on the outer side of the blades; the airflow tends to flow outwards, forming a certain angle with the outer diameter of the blades, and eventually breaks off at the edge, causing the fan to lose some flow. Simultaneously, when an axial cooling fan operates at high speed, the pressure on the upper wing surface is higher than that on the lower wing surface. Under the influence of this pressure difference, the airflow on the lower wing surface will bypass the wingtip and flow to the upper wing surface, generating induced drag. Some existing cooling fans have L-shaped groove structures at the ends of their blades, such as Chinese patent application number 202023141270.4, authorized on October 15, 2021, entitled "New High-Performance Low-Noise Cooling Fan"; others have corrugated groove structures on the blade surfaces, such as Chinese patent application number 202120324118.5, authorized on December 3, 2021, entitled "New High-Performance Low-Noise Cooling Fan Blade". The leading edges of these blades are not tapered, exhibiting a serrated shape and lacking a smooth transition surface with peaks and troughs. However, the combined design of L-shaped and corrugated blades is rare in the aforementioned products and similar products. Furthermore, to increase the airflow velocity at the suction surface of the blades, reduce the risk of stalling, and decrease induced drag, further improvements to the combined design are needed. Summary of the Invention

[0003] To overcome the aforementioned shortcomings, the purpose of this utility model is to provide a guide-flow folding-blade corrugated axial flow cooling fan, thereby solving the technical problems of existing similar products rarely employing a structural design combining folding-blade and corrugated blades, resulting in slow airflow velocity at the suction surface of the blades, a higher risk of stall, and greater induced drag. This objective is achieved through the following technical solution.

[0004] A guide vane type axial flow cooling fan with corrugated blades is disclosed. The main body of the axial flow cooling fan is an impeller, which includes a hub and fan blades. The fan blades are spirally and obliquely spaced at equal intervals on the outer diameter of the hub. The key structural design feature is that the top upper surface of the fan blades has smoothly transitioning curved surfaces with corrugated, equally spaced strip protrusions. These strip protrusions are positioned with a highest point in the middle and lowest points on both sides. At the leading edge of the fan blades, the strip protrusions gradually rise from the lowest points on both sides to a maximum point at 25% of the chord length b. At the trailing edge of the fan blades, the strip protrusions gradually converge at 7% of the chord length b, and the bottom upper surface of the fan blades is a smooth transition plane. Thus, the neat leading edge of the fan blades ensures smooth airflow, the gradual rise to a maximum point at 25% of the chord length b facilitates airflow acceleration, improving fan performance, and the gradual convergence at the trailing edge at 7% of the chord length b prevents disturbance of the tail airflow.

[0005] The connecting strip-shaped protrusions of the fan blades form a smooth transition surface with peaks and troughs. Therefore, the peaks and troughs between these protrusions ensure that the mold formed by the smooth transition surface has no sharp corners and is aesthetically pleasing.

[0006] The top upper wing surface of the fan blade has an upward-curving wing edge with an angle greater than 90 degrees, and the top upper wing surface of the fan blade is the suction surface. The optimal angle is 95 degrees.

[0007] The fan blade has a folded edge with an angle greater than 160 degrees curving downwards along the outer edge of its bottom lower wing surface, which is the pressure surface. The optimal angle is 165 degrees.

[0008] The angle of attack α of the fan blades is 22 degrees. This angle facilitates further increasing the gas velocity at the fan blades and reducing stall.

[0009] This utility model has a reasonable structural design and beautiful appearance. The airflow speed at the suction surface of the fan blade is fast, the risk of stall is small, the induced resistance is small, and the heat dissipation effect is good for the same size. It is suitable for use as a guide-type corrugated blade axial flow cooling fan, and for further improvement of similar products. Attached Figure Description

[0010] Figure 1 This is a partial cross-sectional structural diagram of an embodiment of the present invention. The dotted lines in the diagram represent fan blades, and part A is framed.

[0011] Figure 2 yes Figure 1 Enlarged view of part A.

[0012] Figure 3 yes Figure 1 Schematic diagram of the three-dimensional structure Figure 1 .

[0013] Figure 4yes Figure 1 Schematic diagram of the three-dimensional structure Figure 2 .

[0014] Figure 5 This is a comparison table of simulation models of this utility model and existing conventional blade types.

[0015] Figure 6 This is a comparison curve of CFM and mmH2O at the working point between this utility model and existing conventional blade types.

[0016] Figure 7 This is a comparison table of PQ test data between this utility model and existing conventional blade types.

[0017] The attached figures are numbered and named as follows: 1. Impeller, 101. Hub, 102. Fan blade. Implementation

[0018] The structure and use of this utility model will now be further described with reference to the accompanying drawings. Figures 1-4 As shown, the main body of this axial flow cooling fan is an impeller 1, which includes a hub 101 and fan blades 102. The fan blades are spirally and obliquely spaced at equal intervals on the outer diameter of the hub. The top upper surface of the fan blades has wavy, equidistant strip-shaped protrusions that form a smooth transition surface. These protrusions are positioned at the highest point in the middle and the lowest points on both sides. At the leading edge of the fan blades, the strip-shaped protrusions gradually rise from the lowest points on both sides to reach their highest point at 25% of the chord length b. At the trailing edge of the fan blades, they gradually converge at 7% of the chord length b. The bottom upper surface of the fan blades has smooth transition planes. The connecting points of the fan blades form peaks and troughs in the smooth transition surface.

[0019] The top upper wing surface of the aforementioned fan blade has an upward-curving wing edge with an angle greater than 90 degrees along its outer edge, and the top upper wing surface of the fan blade is the suction surface; the bottom lower wing surface of the fan blade has a downward-curving wing edge with an angle greater than 160 degrees along its outer edge, and the bottom lower wing surface of the fan blade is the pressure surface; the windward angle α of the fan blade is 22 degrees.

[0020] like Figure 5As shown, conventional airfoil designs (without corrugations or flares) primarily improve performance by increasing the angle of attack and airfoil camber, but this also increases drag and the risk of stall. Furthermore, some airflow flows towards the outer edge of the blade, with the airflow at the outer edge flowing from the lower airfoil surface to the upper airfoil surface via the blade tip. The airfoil design of this axial flow cooling fan (corrugated + flared) offers advantages in that the increased curvature of the upper airfoil surface (suction surface) increases airflow velocity and lift. In terms of performance improvement, it reduces the risk of stall while maintaining an angle of attack α of 22 degrees. The corrugated strip-shaped protrusions on the upper airfoil surface guide the airflow along the corrugation direction, reducing airflow loss towards the outer edge and improving performance. Simultaneously, the upper and lower flares at the blade edges effectively reduce airflow from the lower airfoil surface to the upper airfoil surface, reducing induced drag. The upper curvature of the suction surface of this axial flow cooling fan's airfoil is consistent with conventional airfoil B, increasing airflow velocity; the lower curvature of the pressure surface is consistent with conventional airfoil A.

[0021] like Figure 6 As shown, the conventional airfoil design failed to cover the third operating point (105 CFM, 61.22 mmH2O). The corrugated and folded blade design of this airfoil improved efficiency from 48.58 to 51.83 under a back pressure of 60 mmH2O, thus covering the third operating point (105 CFM, 61.22 mmH2O). Figure 7 As shown, the corrugated and folded blade structure design of this blade type, compared with the conventional blade type, has the following advantages: 1) The maximum efficiency remains the same, but the efficiency is improved by 1-3% when the back pressure is between 30-80 mmH2O; 2) The efficiency is brought up earlier, allowing the fan to quickly reach the high-efficiency range.

[0022] In summary, the advantages of this blade design combining corrugations and folded blades are as follows: 1) Increased suction surface curvature leads to increased airflow speed, accelerating efficiency and allowing the fan to quickly reach its high-efficiency range; 2) The corrugations on the suction surface have a certain airflow guiding effect; 3) Maintaining a constant angle of attack reduces the risk of stall; 4) The upper and lower folded blades effectively reduce airflow from the lower blade surface to the upper blade surface, reducing induced drag.

[0023] The above description is intended to illustrate the technical means of this utility model and is not intended to limit the technical scope of this utility model. Any obvious improvements or substitutions made to this utility model by those skilled in the art based on existing common knowledge also fall within the protection scope of the claims of this utility model.

Claims

1. A guide vane type axial cooling fan, the main body of the axial cooling fan is an impeller (1), the impeller comprises a hub (101) and a fan blade (102), the fan blade is spirally and obliquely arranged at an equal distance on the outer diameter of the hub; characterized in that Smooth transition curved surfaces on top upper surfaces of the fan blades (102) are respectively provided with corrugated equidistant strip-shaped protrusions, the strip-shaped protrusions are respectively provided with middle highest points and two side lowest points, the strip-shaped protrusions on the leading edges of the fan blades are respectively slowly protruded from the two side lowest points to the highest points at 25% chord length b, the strip-shaped protrusions on the trailing edges of the fan blades are slowly retracted and arranged in order at 7% chord length b, and bottom upper surfaces of the fan blades are respectively smooth transition planes.

2. The guide vane type axial heat-dissipation fan according to claim 1, wherein Smooth transition curved surfaces are formed between the strip-shaped protrusions on the connecting portions of the fan blades (102).

3. The guide vane type axial heat-dissipation fan according to claim 1, wherein Folded wing edges with upward tilting angles greater than 90 degrees are arranged on the outer edges of the top upper surfaces of the fan blades (102), and the top upper surfaces of the fan blades are suction surfaces.

4. The guide vane type axial cooling fan according to claim 3, wherein Folded wing edges with downward tilting angles greater than 160 degrees are arranged on the outer edges of the bottom lower surfaces of the fan blades (102), and the bottom lower surfaces of the fan blades are pressure surfaces.

5. The guide vane type axial heat-dissipation fan according to claim 1, wherein The wind-angles a of the fan blades (102) are respectively 22 degrees.

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