A centrifugal fan comprising a scale-like biomimetic canted baffle

Abstract

The present application aims to provide a centrifugal fan including a scale-like bionic inclined splitter, comprising a volute upper end cover, a volute lower end cover, a volute outlet, a splitter, and a structure of stacked circular-arc-like simulated scales arranged on the surface of the splitter, which is a circular-arc-like structure with thickness uniformly arranged in the splitter area from the volute upper end cover to the volute lower end cover, thereby dispersing the vortex reaching the surface of the splitter. The present application can reduce the interference noise and vortex noise caused by the rotation of the blade hitting the splitter while ensuring the flow characteristics of the fan, thereby reducing the main noise source of the fan volute.

Description

Technical Field

[0001] The present invention relates to a centrifugal fan, specifically a backward centrifugal fan. Background Technology

[0002] Centrifugal fans, as a type of ventilation equipment, are characterized by their small size, simple structure, good ventilation effect, and economic efficiency. They are widely used in factories, mines, tunnels, cooling towers, vehicles, ships, and buildings for ventilation, dust removal, and cooling, and are closely related to people's living environment. During operation, due to the asymmetry of the volute, the high-speed fluid ejected radially from the impeller impacts the volute wall. Since the baffle is closest to the impeller, it experiences the strongest fluid impact, creating uneven pressure pulsations near the baffle, thus generating noise. This is the main noise source of the fan volute and one of the main noise sources of the entire fan.

[0003] Currently, noise reduction in centrifugal fans primarily focuses on redesigning the rotating blades. Noise reduction designs typically optimize for either reducing leading-edge or trailing-edge noise. Leading-edge noise reduction is mainly achieved through biomimetic-inspired wave-shaped leading-edge designs. Numerous studies have shown that wave-shaped leading-edge blades can improve post-stall dynamic characteristics, delay stall occurrence, and significantly reduce broadband turbulence interference noise. However, this design also increases the complexity of leading-edge turbulence, making it difficult to guarantee the centrifugal fan's aerodynamic performance. Trailing-edge noise reduction often employs serrated structures to disrupt vortices on the blade surface, thereby reducing the jet-wake effect. However, interference noise between the impeller and the volute caused by rotation is also a major noise source. For this part of the noise, the main countermeasures currently involve modifying the volute structure using methods such as tilted or concave volutes, thereby increasing the distance between the impeller and the volute and reducing interference noise.

[0004] However, from the perspective of structural modification, the goal of reducing noise is only considered from the perspective of interference noise. Therefore, in order to reduce the noise near the tongue more effectively and in a more comprehensive way, it is necessary to start from both the reduction of eddy current noise and interference noise to achieve a better noise reduction effect. Summary of the Invention

[0005] The purpose of this invention is to provide a centrifugal fan that achieves noise reduction without affecting the performance of the centrifugal fan, including a scale-type biomimetic inclined tongue.

[0006] The objective of this invention is achieved as follows:

[0007] The present invention discloses a centrifugal fan including a scale-like biomimetic inclined tongue, characterized in that: it includes an upper end cover of a volute, a lower end cover of a volute, a volute outlet, and a tongue, the tongue being inclined, and an arc-shaped simulated scale structure being stacked on the surface of the tongue. This structure is an arc-shaped structure with thickness evenly arranged from the upper end cover of the volute to the lower end cover of the volute, thereby dispersing the eddies reaching the surface of the tongue.

[0008] The present invention may also include:

[0009] 1. The side thickness of the arc-shaped simulated scale structure is controlled by a Bézier curve to ensure a smooth transition. The path of the quadratic Bézier curve is traced by the function B(t) at given points P0, P1, and P2.

[0010] B(t)=(1-t 2 )*P0+2t(1-t)*P1+t 2 P2,t∈(0,1)

[0011] P0 is the vertex of the arc-shaped simulated scale structure, P1 is the innermost point of the side of the arc-shaped simulated scale structure extending towards the center, and P2 is another vertex on the side of P1.

[0012] 2. The arc segment of the tongue near the volute outlet is designed to be tangent to the edge of the tongue and approximately perpendicular to the volute outlet.

[0013] 3. The angle of the tongue is tangent to the arc segment of the tongue outlet.

[0014] 4. The structure of the arc-shaped simulated scale includes a single scale, the single scale is an arc, the radius of the arc is L, the arc length W of the tongue and the plate diameter L of the arc are integer multiples of each other, that is, W = N*L, where N is a natural number.

[0015] 5. The structure of the arc-shaped simulated scale is formed by stacking individual scales in a scale-like manner. In the overlapping part, the scales are stacked at half the radius L of the arc, i.e., L = 2f. At the same time, the scales are stacked from the upper end cover to the lower end cover, so that the overall stacking thickness of the upper end cover is higher than that of the lower end cover.

[0016] The advantages of this invention are as follows: First, the inclined tongue design increases the shortest distance between the blades and the tongue, thereby reducing interference noise near the tongue. Second, the scale-like stacking design on the tongue surface, while conforming to flow characteristics, disrupts the vortex structure near the tongue surface, breaking large vortices down into smaller ones, thus reducing vortex noise. Third, the thickness design of the scale structure utilizes Bayesian curves to control a smooth transition, maintaining good flow characteristics of the fan near the tongue. Based on these advantages, while ensuring the fan's flow characteristics, it is possible to simultaneously reduce interference noise and vortex noise caused by the blades rotating and impacting the tongue, thereby reducing the main noise source of the fan casing. Attached Figure Description

[0017] Figure 1 Original diagram of the wind turbine volute;

[0018] Figure 2 This is a comparison diagram of the tilted tongue and the original tongue;

[0019] Figure 3 Design the main view for a single scale-like arc;

[0020] Figure 4 Design a thickness-direction side view for a single scale-like arc;

[0021] Figure 5 This is a projection of the tongue in the longitudinal plane. Detailed Implementation

[0022] The invention will now be described in more detail with reference to the accompanying drawings:

[0023] Combination Figure 1-5 This invention discloses a fan volute structure with a fish-scale-shaped inclined tongue, designed based on biomimetic principles. The original fan volute structure comprises a volute outlet 1, a tongue 2, a bushing 3, an upper volute cover 4, and a lower volute cover 5. First, a suitable inclination angle is found near the tongue, combined with… Figure 2 As shown, the closest distance *d* between the impeller and the tongue is determined by the curvature of the tongue. Without changing the radius of the tongue's arc, the slope of the tongue outlet is varied, altering the inclination angle *θ*, thus increasing the size of the tongue outlet. During fan operation, the actual distance between the impeller and the tongue increases slightly, reducing interference noise near the tongue. Furthermore, the increased size of the volute outlet increases the cross-sectional area of ​​the region behind the tongue, which was previously similar to a bend in the flow path. At the same flow rate, the increased cross-sectional area reduces the flow velocity. According to the basic principles of Bernoulli's equation, the pressure in this region increases, reducing the adverse pressure gradient and resulting in smoother flow, thus improving fan performance.

[0024] This invention includes a volute solid region, an inclined circular arc tongue 2, and a biomimetic scale structure. Since the main noise is excited near the tongue 2, by studying the scale structure of fish and combining it with the tongue 2, a scale-like corrugated structure is longitudinally distributed from the bottom to the top of the tongue 2 to disrupt the vortex structure near the surface of the tongue 2, while ensuring a certain slope of the tongue 2, thereby reducing the interference noise near the tongue 2.

[0025] A circular arc-shaped structure is stacked on the surface of the tongue 2 to simulate a scale-like design. Specifically, a circular arc-shaped surface design with a certain thickness is evenly arranged in the area of ​​the tongue 2 from the upper end cover 4 to the lower end cover 5 of the volute, which disperses the vortex that reaches the surface of the tongue and disrupts the vortex structure.

[0026] For the thickness of the arc-shaped scale structure on its side, the thickness is controlled by using a Bézier curve to make the curve transition smoothly without affecting the flow.

[0027] The arc segment of the tongue 2 near the volute outlet 1 is designed to be tangent to the edge of the tongue 2 and approximately perpendicular to the volute outlet 1, so as to further guide the fluid near the outlet of the tongue 2 and ensure the performance of the fan.

[0028] The tilt angle of the tongue is tangent to the arc segment of the tongue outlet structure. While ensuring normal flow at the outlet, the tilted tongue can further reduce noise.

[0029] Combination Figures 3-5 The design of the biomimetic tongue section, firstly regarding the biomimetic scales, is based on the shape of fish scales and is designed to be approximately arc-shaped. Figure 3 The display shows the main view of a single scale design. The main control involves the fluctuation of three parameters: the arc radius α, the arc radius L, and the arc length S. These parameters are controlled based on the arc length W of the tongue deflector. The arc radius L is designed to be an integer multiple of the tongue deflector arc length W, i.e., W = N * L, where N is a natural number. This design ensures that the scales at the tongue deflector outlet are tangentially arranged to the tongue deflector height, thus contributing to fluid flow guidance at the outlet. Figure 4 This displays a side view of the scale-like structure along its thickness. In the design process of the scale-like structure, the thickness direction design needs to ensure a smooth transition. Therefore, a Bézier curve is used for the thickness section design curve. Three control points P0, P1, and P2 are selected. According to the definition of a Bézier curve, the path of the quadratic Bézier curve is traced by the function B(t) at the given points P0, P1, and P2.

[0030] B(t)=(1-t2)*P0+2t(1-t)*P1+t2P2,t∈(0,1)

[0031] Figure 5 Show Figure 3 and Figure 4 The unfolded diagram of the stacked structure within the tongue is designed to ensure the disruptive effect of the tongue's scale-like structure on eddies, while simultaneously increasing the tongue's strength. This design utilizes a scale-like stacking pattern to guarantee the strength of the tongue portion and minimize eddy current noise. The overlapping portions are stacked at half the radius of the arc L, i.e., L = 2f, as shown... Figure 5 As shown. The design also incorporates a stacking of the upper and lower end covers, with the overall stack thickness of the upper end cover being greater than that of the lower end cover. This is primarily because the fluid, after being ejected from the volute by the impeller's rotation, exhibits a spiral distribution at the volute outlet, resulting in greater pressure on the upper end cover compared to the lower end cover. Therefore, the stacking method involves a thicker upper end cover to ensure the strength of the tongue and simultaneously achieve the effect of a collapsing vortex.

[0032] Based on the above specific description, the effect achieved by the biomimetic scale-shaped inclined tongue design of the present invention is to further reduce the noise of the main noise source of the fan casing - the tongue noise, thereby reducing the interference noise formed by the tongue and the impeller and reducing the eddy current noise near the tongue to achieve the noise reduction effect.

Claims

1. A centrifugal fan comprising scale-like biomimetic inclined baffles, characterized in that: It includes an upper end cover of the volute, a lower end cover of the volute, a volute outlet, and a tongue. The tongue is inclined and has an arc-shaped simulated scale structure stacked on its surface. This structure is an arc-shaped structure with thickness evenly distributed in the tongue area from the upper end cover of the volute to the lower end cover of the volute, thereby dispersing the eddies reaching the tongue surface. The side thickness of the arc-shaped simulated scale structure is controlled by a Bezier curve to make the curve transition smooth.

2. A centrifugal fan comprising a scale-like biomimetic inclined baffle according to claim 1, characterized in that: The arc segment of the tongue near the volute outlet is designed to be tangent to the edge of the tongue and approximately perpendicular to the volute outlet.

3. A centrifugal fan comprising a scale-like biomimetic inclined baffle according to claim 1, characterized in that: The angle of the tongue is tangent to the arc segment of the tongue outlet.

4. A centrifugal fan comprising a scale-like biomimetic inclined baffle according to claim 1, characterized in that: The structure of the arc-shaped simulated scale includes a single scale, which is an arc with a radius of L. The arc length W of the tongue and the plate diameter L of the arc are integer multiples of each other, i.e., W=N*L, where N is a natural number.

5. A centrifugal fan comprising a scale-like biomimetic inclined diaphragm according to claim 4, characterized in that: The structure of the arc-shaped simulated scales is formed by stacking individual scales in a scale-like manner. The overlapping parts are stacked at half the radius L of the arc, and the stacking starts from the upper end cover and goes down to the lower end cover, so that the overall stacking thickness of the upper end cover is higher than that of the lower end cover.

Images