Air duct and axial flow fan with same

Abstract

The air cylinder comprises a flaring section and a straight cylinder section which are connected, the flaring angle of the flaring section is alpha, a jet flow hole is formed in the straight cylinder section, the jet flow hole penetrates through the cylinder wall of the straight cylinder section, the jet flow hole is close to the joint of the straight cylinder section and the flaring section, and the flaring angle of the straight cylinder section is alpha. The included angle between the center line of the jet hole and the axis of the straight cylinder section is beta, and beta / alpha is larger than or equal to 0.8 and smaller than or equal to 1.1. According to the air duct, when the air duct is applied to the axial flow fan, under the condition that an impeller of the axial flow fan rotates, due to the fact that the jet flow hole is close to the connecting position of the straight duct section and the flaring section, and the included angle formed between the center line of the jet flow hole and the axis of the straight duct section and the flaring angle of the flaring section of the air duct meets the condition that beta / alpha is larger than or equal to 0.8 and smaller than or equal to 1.1; therefore, airflow entering from the jet flow holes can be jetted into the air duct at a reasonable angle and directly strikes an airflow inner vortex formed between the tops of the blades of the impeller and the inner surface of the air duct, and finally the airflow inner vortex is crushed, so that the effect of reducing pneumatic noise is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of axial flow fans, and in particular relates to a wind tube and an axial flow fan having the same. Background Art

[0002] Axial flow fans are usually equipped with a wind tube, which is used to gather airflow. The wind tube includes a flared section and a straight section connected to each other. The flared section is used to accelerate the airflow, and the straight section is used to guide the airflow. The impeller of the axial flow fan is generally located in the straight section and close to the flared section. When the axial flow fan runs at a higher speed, an internal vortex of the airflow will be formed between the top of each blade of the impeller and the inner surface of the wind tube, resulting in a large aerodynamic noise. Summary of the invention

[0003] Therefore, the present invention provides a wind tube, which can solve the technical problem that when an axial flow fan equipped with the wind tube runs at a higher speed, an internal vortex of air flow will be formed in the wind tube, resulting in a large aerodynamic noise.

[0004] In order to solve the above problems, the present invention provides a wind tube, comprising a flared section and a straight section connected to each other, the flared angle of the flared section is α, and a jet hole is constructed on the straight section, the jet hole penetrates the wall of the straight section, and the jet hole is close to the connection between the straight section and the flared section, the angle formed between the center line of the jet hole and the axis of the straight section is β, 0.8≤β / α≤1.1.

[0005] In some embodiments, the jet hole is a tapered hole, a large opening of the tapered hole faces the outside of the straight tube section, and a small opening of the tapered hole faces the inside of the straight tube section.

[0006] In some embodiments, the diameter of the large opening is D 大 , the diameter of the small opening is D 小 , 1.25≤D 大 / D 小 ≤1.5.

[0007] In some embodiments, the number of the jet holes is multiple, and the jet holes are spaced apart along the circumference of the straight tube section, and the sum of the areas of the large openings of the jet holes is S 和 The end of the flared section away from the straight section forms a duct inlet, and the area of ​​the duct inlet is S 入 , 0.007≤S 和 / S 入 ≤0.012.

[0008] In some embodiments, along the axial direction of the wind tube, the length of the wind tube is L, and the end of the flared section away from the straight section forms a wind tube inlet, and the diameter of the wind tube inlet is D 入, 0.75≤D 入 / L≤1.0; and / or, the end of the flared section away from the straight section forms a duct inlet, and the diameter of the duct inlet is D 入 The end of the straight section away from the flared section forms a duct outlet, and the diameter of the duct outlet is D 出 , 0.82≤D 出 / D 入 ≤0.92.

[0009] In some embodiments, along the axial direction of the wind tube, the length of the wind tube is L, and the length of the flared section is L 1 , 0.2L≤L 1 ≤0.3L; and / or, 15°≤α≤40°.

[0010] The present invention also provides an axial flow fan, comprising the above-mentioned wind tube.

[0011] In some embodiments, an impeller is disposed in the straight section, and the impeller includes a hub and blades disposed on the hub. Along the axial direction of the wind tube, the length of the wind tube is L, and the distance between the center point of the hub and the starting end of the straight section is L. 2 , 0.05L≤L 2 ≤0.1L, the jet hole has a jet outlet facing the straight tube section, and the distance between the center point of the jet outlet and the starting end of the straight tube section is L 3 , 0.03L≤L 3 ≤0.06L.

[0012] In some embodiments, the blade includes a blade body and a winglet, the blade body having a blade root, a blade top and a suction surface, the winglet is located at the blade top and extends toward the side where the suction surface is located, and the winglet has an outer side surface facing away from the blade root, and a pit is formed on the outer side surface.

[0013] In some embodiments, the thickness of the winglet is t, and the depth of the pit is h. 坑 , 0.35≤h 坑 / t≤0.65; and / or, the thickness of the winglet is t, the diameter of the pit is D 坑 , 1.5≤D 坑 / t≤2.8.

[0014] In some embodiments, the number of the dimples is multiple, and the dimples are spaced apart along the width direction of the winglet, and the distance between the center points of two adjacent dimples is L. 4 , the diameter of the pit is D 坑 , 1.5≤L 4 / D 坑≤3.5.

[0015] In some embodiments, the number of the pits is multiple, and the pits are spaced apart along the length direction of the winglet, and the distance between the center points of two adjacent pits is L. 2 , the diameter of the pit is D 坑 , 1.1≤L 5 / D 坑 ≤1.6.

[0016] In some embodiments, the blade body further has a leading edge and a trailing edge, the chord length formed by a line between the midpoint of the leading edge and the midpoint of the trailing edge is C, the width of the winglet is W, and 0.02≤W / C≤0.05.

[0017] In some embodiments, the thickness of the winglet is t, 0.10≤t / W≤0.25.

[0018] In some embodiments, the installation angle of the winglet on the blade body is a, 75°≤a≤105°; and / or the winglet and the blade body are integrally formed.

[0019] The present invention provides an air duct and an axial flow fan having the same, which have the following beneficial effects:

[0020] When the wind tube of the present application is applied to an axial flow fan, when the impeller of the axial flow fan rotates, there is a certain pressure difference between the inside and outside of the wind tube. Under the action of the pressure difference, the airflow will also flow in through the jet hole on the straight tube section to form a jet. Since the jet hole is close to the junction of the straight tube section and the flared section, and the angle β formed between the center line of the jet hole and the axis of the straight tube section and the flared angle α of the flared section of the wind tube satisfy 0.8≤β / α≤1.1, the airflow entering from the jet hole will be injected into the wind tube at a reasonable angle and directly hit the airflow inner vortex formed between the top of the impeller blade and the inner surface of the wind tube, and finally break the airflow inner vortex, thereby achieving the effect of reducing the interference noise generated between the dynamic domain and the static domain and reducing the aerodynamic noise. It should be noted that the angle β is determined based on the angle α as the standard, and the angle difference between β and α is not large in order to enable the jet gas to better merge with the mainstream gas in the wind tube while breaking the airflow vortex, so as to reduce the impact and flow unevenness. When β / α is too large, the jet angle is perpendicular to the mainstream gas angle, which is easy to cause adverse effects such as impact; when β / α is too small, the required jet channel is long, the loss along the way is large, which is not conducive to the effect of the jet. Experimental verification shows that the best effect is achieved when β and α meet 0.8≤β / α≤1.1. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0022] Figure 1 It is a structural schematic diagram of an axial flow fan according to an embodiment of the present invention;

[0023] Figure 2 is a side view of an axial flow fan according to an embodiment of the present invention;

[0024] Figure 3 for Figure 2 A cross-sectional view of the axial flow fan in the AA direction of an embodiment of the present invention;

[0025] Figure 4 for Figure 2 A cross-sectional view of the axial flow fan in the BB direction of an embodiment of the present invention;

[0026] Figure 5 for Figure 2 A cross-sectional view of the axial flow fan in the BB direction of an embodiment of the present invention;

[0027] Figure 6 for Figure 5 An enlarged schematic diagram of the axial flow fan impeller at X in an embodiment of the present invention;

[0028] Figure 7 It is a schematic structural diagram of the blades of the axial flow fan according to an embodiment of the present invention;

[0029] Figure 8 A schematic diagram of the structure of a winglet of an axial flow fan blade according to an embodiment of the present invention;

[0030] Fig. 9 is a cross-sectional view of a blade of an axial flow fan according to an embodiment of the present invention;

[0031] Fig.10 It is a structural schematic diagram of an impeller of an axial flow fan according to an embodiment of the present invention;

[0032] Fig.11 for Fig.10 An enlarged schematic diagram of the impeller of the axial flow fan of the embodiment of the present invention at position Y;

[0033] Fig.12 for Fig.10 An enlarged schematic diagram of the impeller of the axial flow fan of the embodiment of the present invention at position Z;

[0034] Fig.13is a schematic structural diagram of an impeller of an axial flow fan according to an embodiment of the present invention from another viewing angle;

[0035] Fig.14 It is a front view of the impeller of the axial flow fan according to an embodiment of the present invention.

[0036] The reference numerals are:

[0037] 1. Expanded section; 2. Straight section; 3. Jet hole; 4. Air duct inlet; 5. Air duct outlet; 6. Hub; 7. Blade; 71. Blade body; 72. Winglet; 8. Blade root; 9. Blade top; 10. Suction surface; 11. Pit; 12. Leading edge; 13. Trailing edge; 14. Pressure surface. DETAILED DESCRIPTION

[0038] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0040] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0041] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0042] See also Figures 1 to 14 As shown, according to an embodiment of the present invention, there is provided a wind duct, comprising a flared section 1 and a straight section 2 connected to each other, the flared angle of the flared section 1 is α, a jet hole 3 is constructed on the straight section 2, the jet hole 3 penetrates the wall of the straight section 2, and the jet hole 3 is close to the junction of the straight section 2 and the flared section 1, the angle formed between the center line of the jet hole 3 and the axis of the straight section 2 is β, 0.8≤β / α≤1.1.

[0043] In this technical solution, when the air duct of the present application is applied to an axial flow fan, when the impeller of the axial flow fan rotates, there is a certain pressure difference between the inside and the outside of the air duct, and under the action of the pressure difference, the airflow will also flow in through the jet hole 3 on the straight tube section 2 to form a jet. Since the jet hole 3 is close to the junction of the straight tube section 2 and the flared section 1, and the angle β formed between the center line of the jet hole 3 and the axis of the straight tube section 2 and the flared angle α of the flared section 1 of the air duct satisfy 0.8≤β / α≤1.1, the airflow entering from the jet hole 3 will be injected into the air duct at a reasonable angle and directly hit the internal vortex of the airflow formed between the top of the impeller blade and the inner surface of the air duct, and finally break up the internal vortex of the airflow, thereby achieving the effect of reducing the interference noise generated between the dynamic domain and the static domain and reducing the aerodynamic noise. It should be noted that the angle β is determined based on the angle α. The small difference between the angles β and α is to enable the jet gas to better merge with the mainstream gas in the wind tube while breaking the air flow vortex, so as to reduce the impact and flow unevenness. When β / α is too large, the jet angle tends to be vertical relative to the mainstream gas angle, which is easy to cause adverse effects such as impact; when β / α is too small, the required jet channel is longer, and the loss along the way is large, which is not conducive to the effect of the jet. Experimental demonstration shows that the best effect is achieved when β and α meet 0.8≤β / α≤1.1. Among them, the flared section 1 is a bell-mouth structure, and the flared angle α of the flared section 1 can be regarded as the angle formed between any generatrix of the inner surface of the flared section 1 and the axis of the wind tube. The inner diameter of the end of the flared section 1 and the starting end of the straight section 2 are the same.

[0044] See also Figure 5 and Figure 6 As shown, the jet hole 3 is a tapered hole, the large opening of the tapered hole faces the outside of the straight tube section 2, and the small opening of the tapered hole faces the inside of the straight tube section 2. When the jet hole 3 is a tapered hole, the airflow can be accelerated in the process of flowing through the jet hole 3, so that the jet gas entering the wind tube can more easily break the vortex inside the airflow.

[0045] See also Figure 5 and Figure 6 As shown, the diameter of the large opening is D 大 , the diameter of the small opening is D 小 , 1.25≤D 大 / D 小 ≤1.5. Diameter of the largest opening D 大 The diameter of the small opening D 小 The ratio between them determines the acceleration of the airflow in the jet hole 3. 大 With D 小 When the ratio between them is too small, the acceleration effect of the jet gas in the jet hole 3 is insufficient. At this time, only the pressure difference between the inside and outside of the wind tube is used as the main force, and the jet gas is difficult to break the vortex inside the airflow. 大 With D小 When the ratio is too large, it means that the diameter of the small opening is too small, the effect area of ​​the jet gas is reduced, the acceleration effect is strong, and the jet gas with too fast speed will not only act on the air flow vortex in the wind tube, but also on the blade itself, affecting the blade performance and not conducive to noise reduction. 大 and D 小 Between 1.25≤D 大 / D 小 When ≤1.5, both the acceleration of the jet gas in the jet hole 3 and the effect of the jet gas can be guaranteed.

[0046] See also Figure 1 and Figure 2 As shown, there are multiple jet holes 3, each jet hole 3 is distributed at intervals along the circumference of the straight tube section 2, and the sum of the areas of the large openings of each jet hole 3 is S 和 The end of the expanded section 1 away from the straight section 2 forms a duct inlet 4, and the area of ​​the duct inlet 4 is S 入 , 0.007≤S 和 / S 入 ≤0.012.

[0047] In this embodiment, multiple jet holes 3 are distributed at intervals along the circumference of the straight tube section 2, indicating that multiple jet gases enter along the circumference of the wind tube, so that each airflow internal vortex formed on the circumference of the wind tube can be broken up, resulting in a better noise reduction effect. At the same time, each jet hole 3 and the wind tube inlet 4 are equivalent to forming two groups of gas inlets on the wind tube, wherein the wind tube inlet 4 is the mainstream gas inlet and each jet hole 3 is a jet gas inlet. When S 和 With S 入 When the ratio between S and is too large, it indicates that the amount of jet gas is large, and the jet formed consumes the impeller in the wind tube excessively, reducing the wind gathering effect of the wind tube. 和 With S 入 When the ratio between S and is too small, it is not enough to form a sufficient jet to break up the internal vortex of the airflow in the wind tube. 和 With S 入 Between 0.007≤S 和 / S 入 When ≤0.012, the multiple jets formed will neither consume the impeller in the wind tube excessively nor effectively break up the internal vortex of the air flow in the wind tube.

[0048] See also Figure 2 and Figure 4 As shown, along the axial direction of the wind tube, the length of the wind tube is L, and the end of the expanded section 1 away from the straight section 2 forms a wind tube inlet 4, and the diameter of the wind tube inlet 4 is D 入 , 0.75≤D 入 / L≤1.0. In this way, the diameter of the air duct inlet 4 and the length of the air duct can be ensured to be within a reasonable range, thereby ensuring the air intake of the air duct and ensuring that the air flow loss along the air duct is not too large.

[0049] See also Figure 4 As shown, the end of the straight section 2 away from the expanded section 1 forms a duct outlet 5, and the diameter of the duct outlet 5 is D 出 , 0.82≤D 出 / D 入 ≤0.92.D 出 With D 入 If the ratio is too large, the mainstream gas entering the wind tube will not be fully accelerated. 出 With D 入 If the ratio between D is too small, the gas flow path will change more severely, increasing the loss of mainstream gas. 出 With D 入 Between 0.82≤D 出 / D 入 When ≤0.92, it can ensure that the mainstream gas is accelerated in the wind tube and that the mainstream gas will not be lost too much in the wind tube.

[0050] See also Figure 2 As shown, along the axial direction of the wind tube, the length of the wind tube is L, and the length of the expansion section 1 is L 1 , 0.2L≤L 1 ≤0.3L. The expansion section 1 is mainly used to accelerate the mainstream gas. The length of the expansion section 1 should not be too long, otherwise it will cause additional losses along the mainstream gas and reduce the overall performance of the axial flow fan. 1 When ≤0.3L, the expansion section 1 can not only effectively accelerate the mainstream gas, but also the mainstream gas will not generate large additional loss along the way when flowing through the expansion section 1. It should be noted that the wall thickness of the wind tube is T. In order to ensure the overall strength of the wind tube, T and L satisfy: 0.018≤T / L≤0.04.

[0051] As a specific implementation, 15°≤α≤40°. When the flaring angle α of the flaring section 1 is too small, the wind gathering and acceleration effect of the flaring section 1 cannot be exerted; when the flaring angle α of the flaring section 1 is too large, additional airflow impact loss will be caused, which is not conducive to the performance of the fan. Experimental demonstration shows that when 15°≤α≤40°, the flaring section 1 not only has a good wind gathering and acceleration effect, but also does not produce a large airflow impact loss.

[0052] According to an embodiment of the present invention, an axial flow fan is further provided, comprising the aforementioned wind tube and an impeller. The impeller is arranged in the straight section 2, and the impeller comprises a hub 6 and blades 7 arranged on the hub 6. Along the axial direction of the wind tube, the length of the wind tube is L, and the distance between the center point of the hub 6 and the starting end of the straight section 2 is L. 2 , 0.05L≤L 2 ≤0.1L, the jet hole 3 has a jet outlet facing the straight tube section 2, and the distance between the center point of the jet outlet and the starting end of the straight tube section 2 is L 3 , 0.03L≤L 3 ≤0.06L.

[0053] In this embodiment, the starting end of the straight section 2 is the end where the straight section 2 and the flared section 1 meet, and the jet outlet of the jet hole 3 is the small opening of the tapered hole. When the impeller is too far away from the starting end of the straight section 2, the gas will lose some kinetic energy and pressure on the path from the flared section 1 to the impeller, resulting in additional energy loss; when the impeller is too close to the starting end of the straight section 2, the gas may not be fully concentrated and evenly distributed just after passing through the collector before entering the impeller, which will have an adverse effect on the performance of the fan. Experimental demonstration shows that when 0.05L≤L 2 ≤0.1L, the impeller is in a suitable position. When the distance between the center point of the jet outlet and the starting end of the straight section 2 satisfies 0.03L≤L 3 When ≤0.06L, it indicates that the position of the jet outlet of the jet hole 3 is accurately configured relative to the position of the impeller, so that the jet gas can fully exert its crushing effect on the internal vortex of the air flow formed between the top of the blade and the inner surface of the wind tube. There are multiple blades, each of which is installed along the circumference of the hub 6, and the blade root 8 of each blade is connected to the hub 6 as a whole. The center point of the hub 6 is on the axis of the wind tube.

[0054] As a specific implementation method, the diameter of the impeller is D 叶 , the inner diameter of the straight section 2 is D 直 , 0.96≤D 叶 / D 直 ≤0.98. When the impeller diameter D 叶 and the inner diameter D of the straight section 2 直 When the impeller and the fan are equal, it is the most ideal situation. At this time, the impeller fits the inner surface of the wind tube without leakage loss. In terms of impeller performance, D 叶 / D 直 The closer it is to 1, the better the fan performance. However, in actual applications, due to the rotation of the impeller, if the diameter of the impeller is equal to the inner diameter of the straight section 2, the blades will inevitably deform during the rotation process. Therefore, considering both aspects, when 0.96≤D 叶 / D 直When ≤0.98, it can ensure that the fan performance has good performance and the safety of fan operation can be guaranteed.

[0055] See also Figure 7 and Figure 8 As shown, the blade 7 includes a blade body 71 and a winglet 72. The blade body 71 has a blade root 8, a blade top 9 and a suction surface 10. The winglet 72 is located at the blade top 9 and extends to the side where the suction surface 10 is located. The winglet 72 has an outer side surface facing away from the blade root 8, and a pit 11 is formed on the outer side surface.

[0056] In this technical solution, since a winglet 72 is provided at the blade tip 9 of the blade body 71, the winglet 72 can hinder the radial flow of the airflow, thereby reducing the radial flow loss of the airflow and reducing the blade torque. At the same time, the pit 11 formed on the outer surface of the winglet 72 can absorb the airflow and break the blade tip vortex generated on the outer side of the blade tip, that is, break the internal vortex of the airflow formed between the blade tip and the inner surface of the wind tube, reduce vortex shedding, and further reduce aerodynamic noise, thereby achieving noise reduction for the axial flow fan. Because the winglet 72 can reduce the radial flow loss of the airflow and the pit 11 thereon can absorb the airflow and reduce vortex shedding, the flow state on the blade surface can be improved, so that the performance of the axial flow fan is significantly improved. Among them, the blade body 71 also has a pressure surface 14.

[0057] See also Figure 8 , Fig.10 and Fig.11 As shown, the thickness of the winglet 72 is t, and the depth of the pit 11 is h 坑 , 0.35≤h 坑 / t≤0.65.

[0058] In this embodiment, when the pit 11 is shallow, the bottom of the pit 11 cannot generate a small adsorption vortex, and cannot play the role of adsorbing airflow to break the blade tip vortex; when the pit 11 is deep, the structural strength of the winglet 72 is greatly affected. Experimental verification shows that when the pit depth h of the pit 11 is 坑 and the thickness t of the winglet 72 satisfy 0.35≤h 坑 When / t≤0.65, both the adsorption effect on the airflow and the structural strength of the winglet 72 can be taken into consideration at the same time.

[0059] See also Figure 8 , Fig.10 and Fig.11 As shown, the diameter of the pit 11 is D 坑 , 1.5≤D 坑 / t≤2.8.

[0060] In this technical solution, when the diameter of the pit 11 is small, the airflow generating the tip vortex will directly pass over the pit 11; when the diameter of the pit 11 is large, it is not enough to guide the airflow and absorb the airflow. 坑 and the thickness t of the winglet 72 satisfy 1.5≤D 坑 When / t≤2.8, it can have a better adsorption effect on the airflow.

[0061] As a specific implementation, there are multiple pits 11, each pit 11 is spaced apart along the width direction of the winglet 72, and the distance between the center points of two adjacent pits 11 is L. 1 , the diameter of the pit 11 is D 坑 , 1.5≤L l / D 坑 ≤3.5.

[0062] In this embodiment, when the distance L between the center points of two adjacent dimples 11 in the width direction of the winglet 72 is 1 and the diameter D of the pit 11 坑 Between 1.5≤L l / D 坑 When ≤3.5, it indicates that the dimples 11 in the same row are evenly distributed on the winglet 72 and have appropriate spacing therebetween, and the dimples 11 in the same row can better act on the airflow, thereby better absorbing the airflow and breaking up the blade tip vortex.

[0063] More specifically, there are a plurality of dimples 11, each dimple 11 is spaced apart along the length direction of the winglet 72, and the distance between the center points of two adjacent dimples 11 is L. 2 , the diameter of the pit 11 is D 坑 , 1.1≤L 2 / D 坑 ≤1.6.

[0064] In this technical solution, when the distance L between the center points of two adjacent dimples 11 in the length direction of the winglet 72 is 2 and the diameter D of the pit 11 坑 Between 1.1≤L 2 / D 坑 When ≤1.6, it indicates that the dimples 11 in the same row are evenly distributed on the winglet 72 and have appropriate spacing therebetween, and the dimples 11 in the same row can better act on the airflow, thereby better absorbing the airflow and breaking up the blade tip vortex.

[0065] It can be understood that, finally, the dimples 11 are evenly distributed in multiple rows and columns on the winglet 72, and the distance between the center points of two adjacent dimples 11 in the same row is L. 1, the distance between the center points of two adjacent pits 11 in the same column is L 2 The purpose of the dimples 11 is to change the gas flow pattern by forming smaller adsorption vortices. When the dimples 11 are evenly distributed in multiple rows and columns on the winglet 72, it can ensure that when the gas flows through the outer side of the winglet 72, vortices with the same rotation trend are generated, which helps to adsorb the airflow. In addition, the even distribution of the dimples 11 in multiple rows and columns on the winglet 72 can also ensure that the dimples 11 will not be inconsistently worn.

[0066] See also Figure 2 and Figure 3 As shown, the blade body 71 also has a leading edge 12 and a trailing edge 13, the chord length formed by the line between the midpoint of the leading edge 12 and the midpoint of the trailing edge 13 is C, the width of the winglet 72 is W, and 0.02≤W / C≤0.05.

[0067] In this embodiment, if the width W of the winglet 72 exceeds a reasonable range, the weight of the blade will increase, and more shaft work will be required to work, resulting in additional losses in the blade. At the same time, the tip vortex is generated within a certain range of the blade tip, not in the entire process. The overly wide part of the winglet does not act on the tip vortex, but increases the resistance, and does not improve the performance of the blade. Experimental demonstration shows that when the width W of the winglet 72 and the average chord length C of the blade body 71 satisfy 0.02≤W / C≤0.05, the width of the winglet 72 can be within a reasonable range, and the blade has a suitable weight, which can not only improve the performance of the blade, but also does not cause additional losses to the blade. Among them, the chord length formed by the line between the midpoint of the leading edge 12 and the midpoint of the trailing edge 13 is the average chord length of the blade body 71.

[0068] See also Figure 2 As shown, the thickness of the winglet 72 is t, and 0.10≤t / W≤0.25.

[0069] In this technical solution, when the thickness t of the winglet 72 is small, the pit 11 formed will have a small pit depth and cannot play the role of adsorbing airflow; when the thickness t of the winglet 72 is large, the weight of the blade will also increase, resulting in additional losses of the blade. Experiments show that when the thickness t of the winglet 72 and the width W of the winglet 72 satisfy 0.10≤t / W≤0.25, the thickness of the winglet 72 can be within a reasonable range, and the blade can further have a suitable weight, so that not only can the pit 11 of appropriate depth be constructed on the winglet 72, but also no additional losses will occur to the blade. Among them, the winglet 72 is an arc-shaped body with appropriate width and thickness.

[0070] As a specific implementation manner, the length of the winglet 72 is greater than or equal to one quarter of the length of the blade tip 9 .

[0071] In this embodiment, the tip vortex is a rotating vortex formed at the blade tip due to the pressure difference between the upper and lower surfaces. The length of the winglet 72 is an important factor affecting the performance of the winglet 72. When the length of the winglet 72 is small, the winglet itself and the pits 11 formed thereon have a weak induction effect on the vortex at the blade tip, which is insufficient to improve efficiency and reduce noise. Therefore, in order for the winglet 72 and the pits 11 thereon to play a better role, the length of the winglet 72 needs to be greater than or equal to one quarter of the length of the blade tip 9. Among them, the length of the winglet 72 and the blade tip 9 refers to the arc length of the winglet 72 and the blade tip 9.

[0072] More specifically, the winglet 72 has a starting end and a trailing end. The starting end of the winglet 72 is connected to the top end of the leading edge 12 , and the trailing end is located between the starting end and the top end of the trailing edge 13 .

[0073] In this technical solution, since the airflow usually moves from the leading edge 12 of the blade body 71 to the trailing edge 13 of the blade body 71, when the starting end of the winglet 72 is connected to the top of the leading edge 12, the winglet 72 can better reduce the radial flow loss of the airflow, and at the same time, the pits 11 on the winglet 72 can better absorb the airflow to break up the blade tip vortex. Among them, the top of the leading edge 12 refers to the end where the leading edge 12 and the blade tip 9 are connected, and the top of the trailing edge 13 refers to the end where the trailing edge 13 and the blade tip 9 are connected.

[0074] See also Figure 4 and Figure 6 As shown, the installation angle of the winglet 72 on the blade body 71 is a, 75°≤a≤105°.

[0075] In this embodiment, when the installation angle of the winglet 72 on the blade body 71 is too large or too small, the effect of the winglet 72 on the radial flow of air will be weak. Experimental verification shows that when the installation angle a of the winglet 72 on the blade body 71 satisfies 75°≤a≤105°, the effect of the winglet 72 on the radial flow of air is better. Among them, the installation angle of the winglet 72 is determined based on the airfoil chord line at the blade tip 9 as a reference, and is set at 90° perpendicular to the airfoil chord line at the blade tip 9.

[0076] As a specific implementation, the winglet 72 and the blade body 71 are integrally formed.

[0077] In this technical solution, if the winglet 72 and the blade body 71 are assembled together as a split structure, when the axial flow fan rotates at high speed, the large centrifugal force can easily separate the winglet 72 and the blade body 71. However, when the winglet 72 and the blade body 71 are integrally formed, this problem can be well prevented from occurring.

[0078] Table 1 below shows a noise comparison between the axial flow fan of the present application and the axial flow fan of the prior art. After the present application optimizes the wind tube and the blades, at the same speed and the same outlet pressure, the total sound pressure level of the fan of the present application at a position twice the impeller diameter directly in front of the impeller is significantly reduced compared to the total sound pressure level of the fan of the prior art.

[0079] Table 1 is a noise comparison between the axial flow fan of the present application and the axial flow fan of the prior art at the same speed.

[0080] Impeller speed (rpm) Outlet pressure (pa) <![CDATA[Total sound pressure level (dB) at 2D in front of impeller 叶 > Axial flow fan of the prior art 1445 200 86 Axial flow fan of the present application 1445 200 82.5

[0081] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0082] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention, and these improvements and variations should also be regarded as the protection scope of the present invention.

Claims

1. A hair dryer, characterized in that: The invention comprises a flared section (1) and a straight section (2) connected to each other, the flared angle of the flared section (1) being α, the straight section (2) being provided with a jet hole (3), the jet hole (3) penetrating the wall of the straight section (2), and the jet hole (3) being close to the junction of the straight section (2) and the flared section (1), the angle formed between the center line of the jet hole (3) and the axis of the straight section (2) being β, 0.8≤β / α≤1.

1.

2. The hair dryer according to claim 1, characterized in that: The jet hole (3) is a tapered hole, the large opening of the tapered hole faces the outside of the straight tube section (2), and the small opening of the tapered hole faces the inside of the straight tube section (2).

3. The hair dryer according to claim 2, characterized in that: The diameter of the large opening is D 大 , the diameter of the small opening is D 小 , 1.25≤D 大 / D 小 ≤1.

5.

4. The hair dryer according to claim 3, characterized in that: The number of the jet holes (3) is multiple, and the jet holes (3) are distributed at intervals along the circumference of the straight tube section (2), and the sum of the areas of the large openings of the jet holes (3) is S. 和 The end of the flared section (1) away from the straight section (2) forms a duct inlet (4), and the area of ​​the duct inlet (4) is S 入 , 0.007≤S 和 / S 入 ≤0.

012.

5. The hair dryer according to claim 1, characterized in that: Along the axial direction of the wind tube, the length of the wind tube is L, and the end of the flared section (1) away from the straight section (2) forms a wind tube inlet (4), and the diameter of the wind tube inlet (4) is D 入 , 0.75≤D 入 / L≤1.0; and / or, the end of the flared section (1) away from the straight section (2) forms a wind tube inlet (4), and the diameter of the wind tube inlet (4) is D 入 The end of the straight tube section (2) away from the flared section (1) forms a duct outlet (5), and the diameter of the duct outlet (5) is D 出 , 0.82≤D 出 / D 入 ≤0.

92.

6. The hair dryer according to claim 1, characterized in that: Along the axial direction of the wind tube, the length of the wind tube is L, the length of the expansion section (1) is L1, 0.2L≤L1≤0.3L; and / or, 15°≤α≤40°.

7. An axial flow fan, characterized in that: The invention comprises the hair dryer as claimed in any one of claims 1 to 6.

8. The axial flow fan according to claim 7, characterized in that: An impeller is arranged in the straight tube section (2), and the impeller comprises a hub (6) and blades (7) arranged on the hub (6). Along the axial direction of the wind tube, the length of the wind tube is L, the distance between the center point of the hub (6) and the starting end of the straight tube section (2) is L2, 0.05L≤L2≤0.1L, and the jet hole (3) has a jet outlet facing the straight tube section (2), and the distance between the center point of the jet outlet and the starting end of the straight tube section (2) is L3, 0.03L≤L3≤0.06L.

9. The axial flow fan according to claim 8, characterized in that: The blade (7) comprises a blade body (71) and a winglet (72), wherein the blade body (71) has a blade root (8), a blade top (9) and a suction surface (10), wherein the winglet (72) is located at the blade top (9) and extends toward the side where the suction surface (10) is located, and wherein the winglet (72) has an outer side surface facing away from the blade root (8), wherein a pit (11) is formed on the outer side surface.

10. The axial flow fan according to claim 9, characterized in that: The thickness of the winglet (72) is t, and the depth of the recess (11) is h. 坑 , 0.35≤h 坑 / t≤0.65; and / or, the thickness of the winglet (72) is t, and the diameter of the pit (11) is D 坑 , 1.5≤D 坑 / t≤2.

8.

11. The axial flow fan according to claim 9, characterized in that: The number of the pits (11) is multiple, and the pits (11) are spaced apart along the width direction of the winglet (72). The distance between the center points of two adjacent pits (11) is L4, and the diameter of the pit (11) is D 坑 , 1.5≤L4 / D 坑 ≤3.

5.

12. The axial flow fan according to claim 9, characterized in that: The number of the pits (11) is multiple, and the pits (11) are spaced apart along the length direction of the winglet (72). The distance between the center points of two adjacent pits (11) is L2, and the diameter of the pit (11) is D. 坑 , 1.1≤L5 / D 坑 ≤1.

6.

13. The axial flow fan according to any one of claims 9 to 12, characterized in that: The blade body (71) further comprises a leading edge (12) and a trailing edge (13); the chord length formed by a line connecting the midpoint of the leading edge (12) and the midpoint of the trailing edge (13) is C; the width of the winglet (72) is W, and 0.02≤W / C≤0.

05.

14. The axial flow fan according to claim 13, characterized in that: The thickness of the winglet (72) is t, 0.10≤t / W≤0.

25.

15. The axial flow fan blade according to any one of claims 9 to 12, characterized in that: The installation angle of the winglet (72) on the blade body (71) is a, 75°≤a≤105°; and / or the winglet (72) and the blade body (71) are integrally formed.

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