A fan suitable for a small diameter cross-flow wind turbine

Abstract

The application relates to the technical field of cross-flow fan, and particularly discloses a fan suitable for a small-diameter cross-flow fan wheel, which comprises a volute, a volute tongue and a fan wheel, the volute and the volute tongue form an air inlet and an air outlet, a cross-flow air duct is arranged in communication between the air inlet and the air outlet, and the fan wheel is arranged in the cross-flow air duct; the volute profile is sequentially connected by a volute linear segment one, a B-spline curve, a volute circular segment one, a volute circular segment two and a volute linear segment two; the volute tongue profile is sequentially connected by a volute tongue linear segment one, a volute tongue circular segment and a volute tongue linear segment two; the volute linear segment one and the volute tongue linear segment one form the air inlet; and the volute linear segment two and the volute tongue linear segment two form the air outlet which is outwardly expanded in a horn shape. By optimizing the volute profile and the volute tongue profile, the airflow separation phenomenon in the small-scale flow field is effectively inhibited, the flow field distribution uniformity is improved, the advantages of effectively inhibiting airflow separation, optimizing flow field distribution, improving fan efficiency, reducing operation noise, ensuring the stability of outlet airflow and the like are achieved.

Description

Technical Field

[0001] This invention relates to the field of cross-flow fan technology, and more particularly to a fan suitable for small-diameter cross-flow impellers. Background Technology

[0002] As electronic devices become increasingly miniaturized and performant, more stringent size and performance requirements are being placed on internal cooling fans. Cross-flow fans, due to their ability to provide wide and uniform airflow within limited spaces, are widely used in various compact devices. Among these, ultra-compact cross-flow fans with impeller diameters ranging from 15mm to 30mm are in increasingly urgent market demand.

[0003] However, existing technologies generally have serious limitations when dealing with the design of such small-diameter cross-flow wind turbines. The industry practice typically involves directly applying a simple geometrically scaled-down version of the volute duct profile, which has been validated on large-sized impellers (e.g., those with diameters greater than 40mm). While this "scale-down design" method is simple and quick, it completely ignores the crucial "scale effect" in fluid mechanics. When the turbine size is significantly reduced, key parameters such as the Reynolds number of the flow field change drastically, resulting in flow characteristics that are drastically different from the large-scale model.

[0004] This direct scaling, ignoring the differences in physical laws, inevitably leads to a series of adverse consequences. First, the curvature radius of the internal flow channels of the scaled-down volute, especially near the volute tongue, becomes excessively small, easily inducing severe airflow separation and secondary eddies in this area. These flow losses directly cause a sharp decline in the fan's total pressure and static pressure performance, while significantly reducing the overall operating efficiency. Second, the interaction between the unstable separated flow and the high-speed rotating impeller generates a large amount of high-frequency eddy noise, resulting in an unpleasant, sharp sound during fan operation and severely deteriorating noise quality. Furthermore, the outlet airflow becomes turbulent and uneven due to flow separation, affecting the stability and uniformity of the air delivery.

[0005] Therefore, how to overcome the inherent defects of traditional scaling design methods on small-diameter cross-flow impellers and effectively suppress airflow separation at small scales has become a core technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] In response to the problems raised in the background art, the purpose of this invention is to provide a fan suitable for small-diameter cross-flow impellers, which has the advantages of effectively suppressing airflow separation, optimizing flow field distribution, improving fan efficiency, reducing operating noise, and ensuring outlet airflow stability.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] A fan suitable for small-diameter cross-flow impeller includes a volute, a volute tongue, and an impeller. The volute and the volute tongue form an air inlet and an air outlet. A cross-flow duct is provided between the air inlet and the air outlet. The impeller is disposed in the cross-flow duct. The rotation of the impeller drives external airflow to enter from the air inlet and be guided by the cross-flow duct to be discharged from the air outlet.

[0009] The volute on one side of the cross-flow duct is a volute profile, which is composed of a volute straight segment one, a B-spline curve, a volute circular arc segment one, a volute circular arc segment two, and a volute straight segment two connected sequentially. The volute straight segment one is a vertically arranged straight segment and serves as the starting reference segment of the volute profile. The B-spline curve, the volute circular arc segment one, and the volute circular arc segment two are all concave curve segments relative to the direction of the impeller. The volute straight segment two is a horizontally arranged straight segment and serves as the ending reference segment of the volute profile. The connection points between the volute straight segment one, the B-spline curve, the volute circular arc segment one, the volute circular arc segment two, and the volute straight segment two are defined as design point b, design point c, design point d, and design point e, respectively.

[0010] The volute tongue is a volute tongue-shaped line on one side of the cross-flow duct. The volute tongue-shaped line is composed of a volute tongue straight segment one, a volute tongue arc segment, and a volute tongue straight segment two connected in sequence. The volute tongue straight segment one is a vertically arranged straight segment and is the starting reference segment of the volute tongue-shaped line. The volute tongue arc segment is a curved segment protruding towards the impeller. The volute tongue straight segment two is an inclined straight segment and is the ending reference segment of the volute tongue-shaped line.

[0011] The first straight segment of the volute and the first straight segment of the volute tongue are parallel to each other and arranged opposite to each other, and the first straight segment of the volute and the first straight segment of the volute tongue form the air inlet;

[0012] The second straight segment of the volute and the second straight segment of the volute tongue form the air outlet, which expands outward in a trumpet shape.

[0013] Preferably, the B-spline curve is controlled and set by design point b, design point i, design point j, design point k, and design point c; the B-spline curve between design point b and design point c is defined as curve bc, and the straight line connecting design point b and design point c is defined as straight line bc;

[0014] Define the angle ∠bij formed by design points b, i, and j as α1; define the angle ∠ijk formed by design points i, j, and k as α2; define the angle ∠jkc formed by design points j, k, and c as α3; define the perpendicular distance between design point i and line bc as h1; define the perpendicular distance between design point j and line bc as h2; define the perpendicular distance between design point k and line bc as h3.

[0015] Among them, 163°<α1<169°, 167°<α2<174°, 160°<α3<168°, 10%D

[0016] Preferably, the diameter of the wind turbine is defined as D, the center of the wind turbine is defined as point O, the distance between the first straight segment of the volute and the first straight segment of the volute tongue is defined as the inlet width L1, the distance between the second straight segment of the volute and the second straight segment of the volute tongue is defined as the outlet width L2, and the included angle between the second straight segment of the volute and the second straight segment of the volute tongue is defined as the expansion angle θ.

[0017] Where L1 = 110%~125%D, L2: L1 = 1.5~1.65, 10°≤θ≤15°.

[0018] Preferably, the minimum distance between the straight segment of the volute and the impeller is defined as the volute clearance l2;

[0019] Among them, l2 = 8.5%~10%D.

[0020] Preferably, the radius of curvature of the circular arc segment of the volute tongue is defined as r1, and the minimum distance between the straight segment of the volute tongue and the impeller is defined as the volute tongue gap l1;

[0021] Where r1≤6%D; l1=9.5%~11%D.

[0022] Preferably, the volute arc segment between design point c and design point d is defined as curve cd;

[0023] Define the radius of curvature of the curve cd as r2, and define the angle ∠cOd formed by the design point c, the center O, and the design point d as α4;

[0024] Where r2 = 75%~85%D, 31°≤α4≤37°.

[0025] Preferably, the volute arc segment between design point d and design point e is defined as curve de;

[0026] ​The radius of curvature of the curve de is defined as r3;

[0027] Wherein, r3 = 285%~300%D.

[0028] Preferably, the curve cd and the second straight segment of the volute are tangent to the curve de.

[0029] Preferably, the midpoint of the curve bc is defined as the design point m;

[0030] Define the straight-line distance between the center O of the circle and the design point b as lb, the straight-line distance between the center O of the circle and the design point m as lm, the straight-line distance between the center O of the circle and the design point c as lc, the straight-line distance between the center O of the circle and the design point d as ld, and the straight-line distance between the center O of the circle and the design point e as le;

[0031] Wherein, lb:lm:lc:ld:le=1:1.04-1.05:1.13-1.14:1.23-1.25:1.38-1.39.

[0032] Compared with the prior art, one of the above technical solutions has the following beneficial effects:

[0033] 1. A cross-flow fan specifically designed for small-diameter cross-flow impellers ranging from 15mm to 30mm is provided. By optimizing the geometric design of the volute profile and volute tongue profile, the airflow separation phenomenon in the small-scale flow field is effectively suppressed, and the uniformity of the flow field distribution is improved. It has the advantages of effectively suppressing airflow separation, optimizing the flow field distribution, improving fan efficiency, reducing operating noise, and ensuring the stability of the outlet airflow.

[0034] 2. Through multi-segment composite profile and optimized volute tongue clearance design, airflow separation is effectively suppressed, making the flow field smoother. This significantly improves wind pressure and efficiency within the same size, while greatly reducing aerodynamic noise, thus solving the core pain point of small-diameter cross-flow fans. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of one embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the structure of the volute and volute tongue according to an embodiment of the present invention;

[0037] Figure 3 yes Figure 1 Design diagram of distance parameters and spread angle parameters;

[0038] Figure 4 The present invention relates to the design of the curve parameters of the volute profile. Figure 1 ;

[0039] Figure 5 The present invention relates to the design of the curve parameters of the volute profile. Figure 2 ;

[0040] Figure 6 The present invention relates to the design of the curve parameters of the volute profile. Figure 3 .

[0041] Among them: volute 1, volute straight segment 11, B-spline curve 12, volute circular arc segment 13, volute circular arc segment 2 14, volute straight segment 2 15, volute tongue 2, volute tongue straight segment 1 21, volute tongue circular arc segment 22, volute tongue straight segment 2 23, impeller 3, cross-flow duct 100, air inlet 101 and air outlet 102. Detailed Implementation

[0042] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0043] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying 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 limitations on this invention.

[0044] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," and "third" may explicitly or implicitly include one or more of that feature.

[0045] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" 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; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0046] The following is in conjunction with the appendix Figures 1 to 6 The technical solution of the present invention will be further illustrated through specific embodiments.

[0047] A fan suitable for small-diameter cross-flow impellers includes a volute 1, a volute tongue 2, and an impeller 3. The volute 1 and the volute tongue 2 form an air inlet 101 and an air outlet 102. A cross-flow duct 100 is provided between the air inlet 101 and the air outlet 102. The impeller 3 is disposed in the cross-flow duct 100. The rotation of the impeller 3 drives the external airflow to enter from the air inlet 101 and be guided by the cross-flow duct 100 to be discharged from the air outlet 102.

[0048] The volute 1 has a volute profile on one side of the cross-flow duct 100. The volute profile is composed of a volute straight segment 11, a B-spline curve 12, a volute arc segment 13, a volute arc segment 2 14, and a volute straight segment 2 15 connected sequentially. The volute straight segment 11 is a vertically arranged straight segment and serves as the starting reference segment of the volute profile. The B-spline curve 12, the volute arc segment 13, and the volute arc segment 2 14 are all concave curves relative to the direction of the impeller 3. The volute straight segment 2 15 is a horizontally arranged straight segment and serves as the ending reference segment of the volute profile. The connection points between the volute straight segment 11, the B-spline curve 12, the volute arc segment 13, the volute arc segment 2 14, and the volute straight segment 2 15 are defined as design point b, design point c, design point d, and design point e, respectively.

[0049] The volute tongue 2 is a volute tongue-shaped line on one side of the cross-flow duct 100. The volute tongue-shaped line is composed of a volute tongue straight segment 21, a volute tongue arc segment 22, and a volute tongue straight segment 23 connected in sequence. The volute tongue straight segment 21 is a vertically arranged straight segment and is the starting reference segment of the volute tongue-shaped line. The volute tongue arc segment 22 is a curved segment protruding towards the impeller 3. The volute tongue straight segment 23 is an inclined straight segment and is the ending reference segment of the volute tongue-shaped line.

[0050] The straight section 11 of the volute and the straight section 21 of the volute tongue are parallel to each other and arranged opposite to each other. The straight section 11 of the volute and the straight section 21 of the volute tongue form the air inlet 101.

[0051] The second straight segment 15 of the volute and the second straight segment 23 of the volute tongue form the air outlet 102, which expands outward in a trumpet shape.

[0052] This invention provides a fan suitable for small-diameter cross-flow impellers, achieving smooth airflow guidance and efficient delivery through the coordinated design of the volute 1, volute tongue 2, and impeller 3. The volute 1 and volute tongue 2 together form the air inlet 101 and air outlet 102, creating a cross-flow duct 100 between them. The impeller 3 is disposed within the cross-flow duct 100. When the impeller 3 rotates, external airflow enters through the air inlet 101, is guided by the cross-flow duct 100, and exits through the air outlet 102. The key to this process lies in the optimized design of the volute and volute tongue profiles to ensure the continuity and smoothness of the airflow path.

[0053] The volute profile is formed by sequentially connecting the volute straight segment 11, the B-spline curve 12, the volute arc segment 13, the volute arc segment 24, and the volute straight segment 25. The volute straight segment 11 serves as the vertical starting reference segment, providing stable air intake guidance. The B-spline curve 12, the volute arc segment 13, and the volute arc segment 24 are all concave towards the impeller 3, conforming to the contour of the impeller 3, thereby maintaining uniform clearance and reducing airflow leakage and turbulence. The volute straight segment 25 serves as the horizontal end reference segment, connecting with the outlet 102 to ensure smooth airflow output. Furthermore, the connection points between each segment are sequentially defined as design point b, design point c, design point d, and design point e. The precise arrangement of these design points allows for a smooth transition of the volute profile, avoiding airflow separation problems caused by abrupt changes in curvature.

[0054] The volute tongue profile is composed of three segments connected sequentially: a straight segment 21, an arc segment 22, and a second straight segment 23. The first straight segment 21 is a vertically positioned starting reference segment, parallel and opposite to the first straight segment 11 of the volute casing, together forming the air inlet 101, thereby eliminating inlet turbulence and ensuring uniform air intake. The arc segment 22 protrudes towards the impeller 3, and its radius of curvature is optimized to precisely control the gap in the volute tongue region, suppressing vortex generation. The second straight segment 23 is an inclined ending reference segment, together with the second straight segment 15 of the volute casing, forming a trumpet-shaped expanding air outlet 102, achieving a smooth transition of airflow deceleration and diffusion.

[0055] Specifically, the coordinated design of the volute profile and the volute tongue profile creates the acceleration and diffusion zones of the cross-flow duct 100. The parallel straight structure of the inlet 101 ensures uniform air intake, while the trumpet-shaped expansion of the outlet 102 reduces outlet velocity pulsation. Thus, the entire cross-flow duct 100 forms a continuous airflow guiding path from inlet to outlet, effectively mitigating the flow separation and energy loss problems caused by traditional scaling designs in small-diameter fans. This design not only improves airflow stability but also significantly reduces high-frequency eddy noise, thereby meeting the high-efficiency and low-noise requirements of small-diameter cross-flow impeller fans.

[0056] Furthermore, the B-spline curve 12 is controlled and set by design point b, design point i, design point j, design point k and design point c; the B-spline curve 12 between design point b and design point c is defined as curve bc, and the straight line connecting design point b and design point c is defined as straight line bc;

[0057] Define the angle ∠bij formed by design points b, i, and j as α1; define the angle ∠ijk formed by design points i, j, and k as α2; define the angle ∠jkc formed by design points j, k, and c as α3; define the perpendicular distance between design point i and line bc as h1; define the perpendicular distance between design point j and line bc as h2; define the perpendicular distance between design point k and line bc as h3.

[0058] Among them, 163°<α1<169°, 167°<α2<174°, 160°<α3<168°, 10%D

[0059] Specifically, B-spline curve 12 refers to a smooth curve whose shape is defined by multiple control points. Its purpose is to ensure that the transition characteristics of the curve in a small-diameter cross-flow impeller meet the flow field requirements. Design points b, i, j, k, and c together constitute the control point set of curve bc, and the positional relationship of these control points determines the overall shape of the curve. Angles α1, α2, and α3 are used to constrain the geometry of the initial, middle, and final segments of the curve, respectively, to avoid airflow separation caused by abrupt changes in curvature. Vertical distances h1, h2, and h3 are used to adjust the offset of the curve relative to the straight line bc, aiming to optimize the degree of convexity of the curve, thereby guiding the airflow to accelerate smoothly and reducing energy loss.

[0060] ​Specifically, by precisely defining the geometric parameters of B-spline curve 12, the airflow separation problem caused by scale effects in small-diameter cross-flow impellers was solved. The relative positions of design points b, i, j, k, and c were strictly constrained, allowing curve bc to dynamically adapt to fluid behavior within a limited space. The angle α1 was set to a range of 163° to 169°, ensuring a smooth transition at the beginning of the curve and preventing premature airflow separation near the impeller inlet due to an excessively small angle. The angle α2 was set to a range of 167° to 174°, making the middle section of the curve nearly straight, reducing unnecessary curvature fluctuations, and maintaining stable airflow adhesion in the acceleration region. The angle α3 was set to a range of 160° to 168°, ensuring a smooth connection between the end of the curve and subsequent curve segments, eliminating vortices that might be caused by sharp bends. Furthermore, the vertical distances h1, h2, and h3 are constrained to adjust the offsets at the beginning, middle, and end of the curve, respectively. This allows the curve to form a moderate convexity and convergence, guiding the airflow smoothly into the acceleration region and transitioning smoothly to the outlet, reducing disturbances and secondary flows. The synergistic effect of these parameters constructs an optimized curve adapted to small-scale flow fields, effectively suppressing airflow separation points, improving the overall aerodynamic performance of the fan, increasing fan efficiency, and reducing high-frequency noise. Simultaneously, this design forms an organic whole with other components of the volute profile, further optimizing the airflow acceleration and diffusion process, demonstrating its unique advantages in small-diameter cross-flow fan design.

[0061] Furthermore, the diameter of the impeller 3 is defined as D, the center of the impeller 3 is defined as point O, the distance between the first straight segment 11 of the volute and the first straight segment 21 of the volute tongue is defined as the inlet width L1, the distance between the second straight segment 15 of the volute and the second straight segment 23 of the volute tongue is defined as the outlet width L2, and the angle between the second straight segment 15 of the volute and the second straight segment 23 of the volute tongue is defined as the expansion angle θ.

[0062] Where L1 = 110%D ~ 125%D, L2: L1 = 1.5 ~ 1.65, 10° ≤ θ ≤ 15°.

[0063] In practical applications, the inlet width L1 refers to the distance between the straight section 11 of the volute and the straight section 21 of the volute tongue. This distance can be achieved through precise machining processes to ensure appropriate velocity and pressure distribution when the airflow enters the cross-flow duct 100. The outlet width L2 refers to the distance between the straight section 15 of the volute and the straight section 23 of the volute tongue. This distance is designed to allow the airflow to diffuse smoothly at the outlet 102 and reduce energy loss. The expansion angle θ is the angle between the straight section 15 of the volute and the straight section 23 of the volute tongue. This angle is designed to optimize the curvature of the airflow diffusion path, thereby suppressing vortex shedding and improving the uniformity of the outlet airflow.

[0064] Specifically, by establishing a proportional relationship between the inlet width L1, the outlet width L2, and the impeller diameter D, and limiting the range of the expansion angle θ, the diffusion behavior of the outlet airflow of a small-diameter cross-flow fan is systematically optimized, effectively suppressing airflow separation and thus improving the stability and uniformity of the outlet airflow. The inlet width L1 is set within the range of 110%D to 125%D based on the impeller diameter D. This proportional relationship fully considers the balance between fluid inertia and viscous forces under small dimensions, avoiding flow field blockage caused by excessively small inlet gaps or airflow disturbance caused by excessively large gaps, laying the foundation for a smooth transition of subsequent airflow to the outlet. The ratio of the inlet width L1 to the outlet width L2 is set between 1.5 and 1.65, and the expansion angle θ of the outlet 102 is set between 10° and 15°. By precisely controlling the opening width and expansion angle of the outlet 102, the high-speed airflow can be decelerated and diffused in a gradual manner. This prevents boundary layer separation caused by excessive expansion and avoids low dynamic pressure conversion efficiency caused by insufficient expansion, thus ensuring that the airflow energy is efficiently converted into static pressure. It also suppresses vortex shedding caused by excessive angle and overcomes insufficient diffusion caused by excessively small angle, ultimately achieving uniform and stable output of the outlet airflow.

[0065] Based on this, the aforementioned fan, by rationally setting the inlet width L1, outlet width L2, and expansion angle θ, not only solves the inherent defects of traditional scaling design methods for small-diameter cross-flow impellers, but also significantly improves the overall performance of the fan. By optimizing these key parameters, smooth airflow is achieved within the cross-flow duct 100, particularly creating an ideal diffusion effect in the outlet 102 region, effectively reducing airflow separation and energy loss, thereby improving the fan's operating efficiency and outlet stability.

[0066] Furthermore, the minimum distance between the straight segment 11 of the volute and the impeller 3 is defined as the volute clearance l2;

[0067] Among them, l2 = 8.5%D~10%D.

[0068] The volute clearance l2 refers to the minimum distance between the straight section 11 of the volute and the impeller 3. The purpose of introducing this parameter is to optimize the clearance value to avoid airflow separation and blockage caused by too small a clearance, while preventing vortex formation and energy dissipation caused by too large a clearance.

[0069] Specifically, the volute clearance l2 is designed with full consideration of the changing characteristics of fluids in small-diameter cross-flow fans. Under small-size conditions, traditional fixed-size clearance designs are insufficient to meet practical needs. By limiting l2 to 8.5% to 10% of the impeller diameter D, the clearance size is ensured to adapt to impellers of different diameters, maintaining a smooth airflow transition within the cross-flow duct 100. Furthermore, the volute clearance l2, along with the volute profile and volute tongue profile, forms a complete airflow guiding system, effectively suppressing airflow separation at small scales. In particular, when the volute clearance l2 is combined with features such as the B-spline curve 12 and the volute arc segment 13, it better maintains airflow velocity and guides it towards the outlet, thereby ensuring smooth airflow and improving the overall operating efficiency of the fan.

[0070] Furthermore, this technical solution, through precise control of the volute clearance l2, not only solves the flow field problem caused by improper clearance but also achieves a good fit with the overall structure of the fan. For example, at the air inlet 101, a reasonable clearance setting ensures smooth airflow, while in the cross-flow duct 100, it effectively reduces energy loss, ensures smooth airflow, and ultimately achieves a comprehensive improvement in fan performance.

[0071] Furthermore, the radius of curvature of the circular arc segment 22 of the volute tongue is defined as r1, and the minimum distance between the straight segment 21 of the volute tongue and the impeller 3 is defined as the volute tongue gap l1;

[0072] Where r1≤6%D; l1=9.5%D~11%D.

[0073] The radius of curvature r1 of the volute tongue arc segment 22 refers to the curvature of the curved segment protruding towards the impeller 3 in the volute tongue profile. Its purpose is to ensure that the geometric curvature of the volute tongue region is not too large, avoiding sharp inflection points at small dimensions due to an excessively small radius of curvature, thereby reducing the tendency of airflow separation and vortex generation at the volute tongue. The volute tongue gap l1 refers to the minimum distance between the straight segment 21 of the volute tongue and the impeller 3. It can be achieved by adjusting the design parameters of the volute tongue profile. Its purpose is to ensure that the volute tongue gap is within a reasonable range suitable for small-sized impellers, avoiding both flow field blockage and energy dissipation caused by an excessively small gap, and preventing airflow backflow and disturbance caused by an excessively large gap, ensuring a smooth transition of airflow in the volute tongue region.

[0074] Specifically, by coordinating and limiting the numerical range of the radius of curvature r1 of the volute tongue arc segment 22 and the volute tongue gap l1, the flow field structure in the volute tongue region is optimized to address the scale effect problem unique to small-diameter cross-flow wind turbines, thereby suppressing airflow separation and reducing noise. Further, limiting the radius of curvature r1 of the volute tongue arc segment 22 to no more than 6% of the wind turbine diameter D effectively avoids sharp inflection points due to excessively small curvature radii, thus reducing the tendency of airflow separation and vortex generation at the volute tongue. Simultaneously, limiting the minimum distance l1 between the straight segment 21 of the volute tongue and the wind turbine 3 to 9.5% to 11% of the wind turbine diameter D ensures a smooth transition of airflow in the volute tongue region, effectively reducing high-frequency vortex noise and improving wind pressure conversion efficiency. Overall, the precise matching of the radius of curvature r1 of the volute tongue arc segment 22 and the volute tongue gap l1 enables the volute tongue profile to achieve a balance between airflow guidance and energy conversion under small-diameter conditions, significantly improving the performance stability of the wind turbine in a compact space. Furthermore, this scheme, combined with the aforementioned volute profile design, optimizes the overall flow field structure of the cross-flow duct, further improving the fan's operating efficiency and airflow stability.

[0075] Furthermore, the volute arc segment 13 between the design point c and the design point d is defined as curve cd;

[0076] Define the radius of curvature of the curve cd as r2, and define the angle ∠cOd formed by the design point c, the center O, and the design point d as α4;

[0077] Where r2 = 75%D~85%D, 31°≤α4≤37°.

[0078] Curve cd refers to the geometric shape of the volute arc segment 13 between design point c and design point d. It can be achieved using a precisely calculated circular arc curve, with the aim of ensuring a smooth transition and velocity maintenance in the subsequent part of the airflow in the acceleration region. The radius of curvature r2 refers to the degree of curvature of curve cd, with the aim of avoiding insufficient airflow separation or diffusion due to excessive or insufficient curvature. The included angle α4 is the spatial angle formed by design point c, the center O, and design point d, with the aim of matching the rate of change of airflow direction with the inertial force of the small-scale flow field, thereby eliminating the risk of sudden changes in local flow.

[0079] Specifically, by precisely controlling the geometry of curve cd, the flow stability problem in the acceleration region of small-diameter fans is effectively solved. Based on the diameter D of the impeller 3, the radius of curvature r2 of curve cd is set within the range of 75%D to 85%D. This range avoids both insufficient airflow diffusion due to an excessively large radius of curvature, which would prevent velocity maintenance, and airflow separation caused by a sharp bend due to an excessively small radius of curvature. This ensures a smooth transition of airflow in the subsequent acceleration region and continuous directional force. Simultaneously, based on the spatial relationship between design point c, center O, and design point d, the included angle α4 is limited to the range of 31° to 37°. This angle design matches the rate of change of airflow direction with the inertial force of the small-sized flow field, eliminating the risk of sudden local flow changes. This not only suppresses vortex generation but also strengthens the geometric continuity with the subsequent volute arc segment 14, ultimately achieving efficient energy transfer and improved airflow stability.

[0080] Furthermore, the volute arc segment 14 between the design point d and the design point e is defined as curve de;

[0081] The radius of curvature of the curve de is defined as r3;

[0082] Where r3 = 285%D~300%D.

[0083] In practical applications, curve de refers to the section on the volute arc segment 14 that connects design points d and e. Its purpose is to guide the airflow smoothly from the acceleration zone to the outlet. The radius of curvature r3 is a key parameter for optimizing small-diameter cross-flow fans. By limiting r3 to the range of 285% to 300% of the impeller diameter D, it is possible to effectively balance deceleration efficiency and flow stability, and avoid eddies and energy dissipation caused by mismatched radius of curvature.

[0084] Specifically, by clearly defining the boundaries of curve de and its radius of curvature, a smooth connection between the deceleration and diffusion regions and the outlet profile is ensured. Based on the spatial relationship between the impeller's geometric center O and design points d and e, curve de is precisely positioned, thus avoiding airflow separation problems caused by abrupt changes in the profile. Simultaneously, by setting a specific range for r3, the high-speed airflow can achieve gradual deceleration on curve de, smoothly converting dynamic pressure into static pressure, ensuring the uniformity and stability of the outlet airflow. Furthermore, this technique, combined with the aforementioned overall design of the volute profile, further optimizes the flow characteristics of the airflow throughout the entire cross-flow duct 100, significantly reducing energy loss and noise caused by flow field instability, reflecting a deep consideration of the scale effect of small-sized fans. Through the above technical solutions, not only is the problem of unstable deceleration and diffusion of high-speed airflow solved, but the overall operating efficiency of the fan and the quality of the outlet airflow are also improved, fully demonstrating the innovation and practicality of this technical solution in the design of small-diameter cross-flow fans.

[0085] Furthermore, the curve cd and the straight line segment 15 of the volute are tangent to the curve de.

[0086] By ensuring that curve cd is tangent to curve de, the potential curvature abruptness problem in the transition region from volute arc segment 13 to volute arc segment 14 is eliminated, thus maintaining the continuity of airflow during velocity guidance and pressure conversion. Simultaneously, the design of tangency between volute straight segment 15 and curve de avoids angular changes from the deceleration and diffusion region to the straight segment at the outlet, preventing vortices from forming due to abrupt changes in airflow direction when entering the funnel-shaped expansion outlet. This tangent design is particularly important in small-diameter cross-flow fans because the scale effect amplifies the flow's sensitivity to profile continuity; a smooth geometric transition effectively suppresses airflow separation points, improves the stability of the deceleration and diffusion process, and ensures uniform diffusion of the outlet airflow.

[0087] Furthermore, the midpoint of the curve bc is defined as the design point m;

[0088] Define the straight-line distance between the center O of the circle and the design point b as lb, the straight-line distance between the center O of the circle and the design point m as lm, the straight-line distance between the center O of the circle and the design point c as lc, the straight-line distance between the center O of the circle and the design point d as ld, and the straight-line distance between the center O of the circle and the design point e as le;

[0089] Wherein, lb:lm:lc:ld:le=1:1.04-1.05:1.13-1.14:1.23-1.25:1.38-1.39.

[0090] Specifically, the design point m refers to the geometric center of curve bc, and its function is to provide an intermediate control reference for B-spline curve 12. In practical applications, the design point m can be determined by calculating the midpoint of the parametric equation of curve bc, the purpose of which is to ensure that the curve shape can be precisely controlled through distance parameters. Among them, lb, as the reference distance, refers to the straight-line distance from the center O to the design point b, and its ratio to lm is set in the range of 1.04-1.05. This ratio ensures that the middle of curve bc expands appropriately, avoiding premature airflow separation in the initial acceleration section due to abrupt curvature changes. The ratio of lc to lb is set in the range of 1.13-1.14. This ratio ensures a smooth connection between the end of curve bc and arc cd, preventing vortices from being generated in the airflow at the connection point due to abrupt changes in direction. The ratio settings of ld and le further continue the gradual expansion trend of the acceleration region, guiding the airflow to transition evenly to the outlet section.

[0091] In detail, the above scheme systematically optimizes the geometry of the airflow acceleration region by establishing a distance ratio system from the center of the impeller to key points of the volute profile, thereby effectively suppressing airflow separation at small scales. In its implementation, lb serves as the reference distance, and its ratio to lm, ranging from 1.04 to 1.05, ensures a moderate outward expansion of the middle of curve BC, maintaining boundary layer stability for small-diameter impellers. lc, at a ratio of 1.13 to 1.14 times that of lb, ensures a smooth transition between the end of curve BC and the arc CD, preventing vortices from forming at the connection point due to abrupt changes in airflow direction. The subsequent ratios of ld and le further extend the gradual expansion trend of the acceleration region, guiding the airflow to transition evenly to the outlet section. The synergistic effect of the overall proportional relationships allows curve BC and arc CD to form a continuous and efficient acceleration channel, maximizing airflow kinetic energy conversion efficiency within a limited space while avoiding the flow instability problems caused by neglecting scale effects in traditional scaling designs.

[0092] Based on the overall structure of the aforementioned wind turbine, this solution solves the problem of local airflow separation in the acceleration region during operation of a small-diameter cross-flow wind turbine by precisely quantifying the specific curvature distribution of the B-spline curve. This significantly improves the energy conversion efficiency in the airflow acceleration region and effectively reduces the noise problem caused by airflow separation.

[0093] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the present invention.

Claims

1. A fan suitable for use in a small diameter through-flow wind turbine, characterised in that: The application relates to a kind of axial fan, including volute (1), volute tongue (2) and wind wheel (3), the volute (1) and the volute tongue (2) constitute air inlet (101) and air outlet (102), air inlet (101) and air outlet (102) are connected with the through-flow air channel (100) between, the wind wheel (3) is arranged in the through-flow air channel (100), the wind wheel (3) rotation drives external airflow from the air inlet (101) into, and is guided from the air outlet (102) by the through-flow air channel (100) and is discharged; The volute (1) is volute profile on one side of the through-flow air channel (100), the volute profile is sequentially connected by volute straight line segment one (11), B spline curve (12), volute circular arc segment one (13), volute circular arc segment two (14) and volute straight line segment two (15); The volute straight line segment one (11) is a vertically arranged straight line segment, the volute straight line segment one (11) is the starting reference segment of the volute profile, the B spline curve (12), the volute circular arc segment one (13) and the volute circular arc segment two (14) are all curve segments concave relative to the direction of the wind wheel (3), the volute straight line segment two (15) is a horizontally arranged straight line segment, and the volute straight line segment two (15) is the terminal reference segment of the volute profile; The connecting points between the volute straight line segment one (11), B spline curve (12), volute circular arc segment one (13), volute circular arc segment two (14) and the volute straight line segment two (15) are defined as design point b, design point c, design point d and design point e in sequence; The volute tongue (2) is volute tongue profile on one side of the through-flow air channel (100), the volute tongue profile is sequentially connected by volute tongue straight line segment one (21), volute tongue circular arc segment (22) and volute tongue straight line segment two (23); The volute tongue straight line segment one (21) is a vertically arranged straight line segment, the volute tongue straight line segment one (21) is the starting reference segment of the volute tongue profile, the volute tongue circular arc segment (22) is a curve segment convex to the direction of the wind wheel (3), the volute tongue straight line segment two (23) is an obliquely arranged straight line segment, and the volute tongue straight line segment two (23) is the terminal reference segment of the volute tongue profile; The volute straight line segment one (11) and the volute tongue straight line segment one (21) are arranged opposite to each other and parallel to each other, and the volute straight line segment one (11) and the volute tongue straight line segment one (21) constitute the air inlet (101); The volute straight line segment two (15) and the volute tongue straight line segment two (23) constitute the air outlet (102), and the air outlet (102) is trumpet-shaped and expands outward.

2. A fan suitable for use in a small diameter cross flow wind turbine according to claim 1, characterised in that: The B spline curve (12) is arranged by design point b, design point i, design point j, design point k and design point c; the B spline curve (12) between the design point b and the design point c is defined as curve bc, and the straight line connecting line between the design point b and the design point c is defined as straight line bc. An angle ∠bij formed by the design points b, i and j is defined as α1; an angle ∠ijk formed by the design points i, j and k is defined as α2; an angle ∠jkc formed by the design points j, k and c is defined as α3; a perpendicular distance between the design point i and the straight line bc is defined as h1; a perpendicular distance between the design point j and the straight line bc is defined as h2; a perpendicular distance between the design point k and the straight line bc is defined as h3; Wherein, 163° < α1 < 169°, 167° < α2 < 174°, 160° < α3 < 168°, 10%D < h1 < 13.5%D, 14.5%D < h2 < 18%D, 12.5%D < h3 < 16%D.

3. A fan suitable for use in a small diameter cross flow wind turbine according to claim 2, characterised in that: A diameter of the wind wheel (3) is defined as D, a center of the wind wheel (3) is defined as the center O, a distance between the straight line segment one (11) of the volute and the straight line segment one (21) of the tongue is defined as the inlet width L1, a distance between the straight line segment two (15) of the volute and the straight line segment two (23) of the tongue is defined as the outlet width L2, and an angle between the straight line segment two (15) of the volute and the straight line segment two (23) of the tongue is defined as the expansion angle θ; Wherein, L1 = 110% ~ 125%D, L2: L1 = 1.5 ~ 1.65, 10° ≤ θ ≤ 15°.

4. A fan suitable for use in a small diameter cross flow wind turbine according to claim 3, characterised in that: A minimum distance between the straight line segment one (11) of the volute and the wind wheel (3) is defined as the volute gap l2; Wherein, l2 = 8.5% ~ 10%D.

5. A fan suitable for use in a small diameter cross flow wind turbine according to claim 3, characterised in that: A curvature radius of the tongue circular arc segment (22) is defined as r1, and a minimum distance between the straight line segment one (21) of the tongue and the wind wheel (3) is defined as the tongue gap l1; Wherein, r1 ≤ 6%D; l1 = 9.5% ~ 11%D.

6. A fan suitable for use in a small diameter cross flow wind turbine according to claim 3, characterised in that: The volute circular arc segment one (13) between the design point c and the design point d is defined as the curve cd; A curvature radius of the curve cd is defined as r2, and an angle ∠cOd formed by the design point c, the center O and the design point d is defined as α4; Wherein, r2 = 75% ~ 85%D, 31° ≤ α4 ≤ 37°.

7. A fan suitable for use in a small diameter cross flow wind turbine according to claim 6, characterised in that: The volute circular arc segment two (14) between the design point d and the design point e is defined as the curve de; A curvature radius of the curve de is defined as r3; Wherein, r3 = 285% ~ 300%D.

8. A fan suitable for use in a small diameter cross flow wind turbine according to claim 7, characterised in that: The curve cd and the straight line segment two (15) of the volute are respectively tangent to the curve de.

9. A fan suitable for use in a small diameter cross flow wind turbine according to claim 3, characterised in that: A midpoint of the curve bc is defined as the design point m; A straight line distance between the center O and the design point b is defined as lb, a straight line distance between the center O and the design point m is defined as lm, a straight line distance between the center O and the design point c is defined as lc, a straight line distance between the center O and the design point d is defined as ld, and a straight line distance between the center O and the design point e is defined as le; Wherein, lb: lm: lc: ld: le = 1: 1.04-1.05: 1.13-1.14: 1.23-1.25: 1.38-1.39.

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