CN109058157B - Centrifugal impeller and hollow blade thereof - Google Patents
Centrifugal impeller and hollow blade thereof Download PDFInfo
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- CN109058157B CN109058157B CN201810935033.3A CN201810935033A CN109058157B CN 109058157 B CN109058157 B CN 109058157B CN 201810935033 A CN201810935033 A CN 201810935033A CN 109058157 B CN109058157 B CN 109058157B
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- blade
- overflowing
- suction surface
- overflowing hole
- cavity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/26—Rotors specially for elastic fluids
- F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
- F04D29/281—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps for fans or blowers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/26—Rotors specially for elastic fluids
- F04D29/28—Rotors specially for elastic fluids for centrifugal or helico-centrifugal pumps for radial-flow or helico-centrifugal pumps
- F04D29/30—Vanes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D29/00—Details, component parts, or accessories
- F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
- F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
- F04D29/667—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by influencing the flow pattern, e.g. suppression of turbulence
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
The invention discloses a hollow blade which comprises a blade body, wherein a cavity is formed in the blade body, and a pressure surface and a suction surface of the blade body are respectively provided with a first overflowing hole and a second overflowing hole so that gas on the outer side of the pressure surface can flow into the outer side of the suction surface through the cavity. The hollow blade provided by the invention is provided with the cavity, and the cavity can slow down the speed of the airflow passing through the first overflowing hole and the second overflowing hole, so that the airflow flows out of the suction surface at a lower and more uniform speed, and the influence of the airflow on the main airflow in the impeller flow passage is reduced.
Description
Technical Field
The invention relates to the technical field of fluid machinery, in particular to a hollow blade. The invention also relates to a centrifugal impeller comprising the hollow blade.
Background
The centrifugal fan applies work to the gas through the rotation of the impeller, and the power loss in the fan mainly comes from separation loss, impact loss, secondary flow loss and wake loss. The principle of the separation loss is that in the process of flowing of a gas medium in an impeller flow channel, the cross section of the impeller flow channel is continuously increased, the flowing speed of the gas is slowly reduced, the thickness of a boundary layer on the surface of a blade is increased, the flowing speed of the gas flow is gradually reduced under the action of frictional resistance for fluid in the boundary layer on the surface of the blade, the kinetic energy of the fluid outside the boundary layer is continuously reduced, and the kinetic energy cannot be transferred to the fluid in the boundary layer, so that the frictional resistance is overcome. In addition, the gas flow velocity is reduced, and simultaneously, the pressure of the gas is continuously increased along the flow direction, so that the fluid velocity in the boundary layer near the tail edge of the blade is reduced to zero, the flow direction is reversed under the action of the counter pressure gradient, the backflow is generated, the backflow is taken away by the main flow, the main flow is separated from the surface of the blade, and a vortex is formed, namely, the vortex is separated. Fluid movement by vortex shedding, turbulence, or the like, which deflects the gaseous medium away from the most favorable flow direction, can reduce efficiency, impair acoustic performance and cause instability in the fan's characteristic curve, reducing fan efficiency.
In the prior art, a designer applies a design of a perforated structure to a blade, airflow enters from a pressure surface and flows out from a suction surface through an airflow hole, and due to the fact that the pressure difference between the pressure surface and the suction surface is large, the airflow has high flow velocity when flowing out from the suction surface, the speed of a main flow near the suction surface is seriously disturbed, and although the effect of providing kinetic energy to low-speed fluid on the suction surface is achieved, if the control is not proper, the flowing condition near the suction surface is easily deteriorated.
Therefore, how to avoid the interference of the air flow from the air flow holes to the main air flow is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide a hollow blade, wherein a cavity is formed in a blade body of the hollow blade, so that the air flow flowing to a suction surface can be buffered, and the air flow flowing out of an air flow hole is prevented from interfering with a main air flow. It is another object of the present invention to provide a centrifugal impeller comprising the above hollow blades.
In order to achieve the purpose, the invention provides a hollow blade which comprises a blade body, wherein a cavity is formed in the blade body, and a pressure surface and a suction surface of the blade body are respectively provided with a first overflowing hole and a second overflowing hole so that gas outside the pressure surface can flow into the outside of the suction surface through the cavity.
Preferably, the blade body comprises a first blade and a second blade, the first blade and the second blade constituting the pressure surface and the suction surface, respectively.
Preferably, the distance between the first overflowing hole and the tail edge of the blade body is smaller than or equal to 1/3 of the length of the pressure surface, and the second overflowing hole is located at the rear part of the suction surface.
Preferably, the total area of the first overflowing holes is smaller than or equal to the total area of the second overflowing holes.
Preferably, the number of the second overflowing holes is larger than that of the first overflowing holes, and the diameter of the second overflowing holes is smaller than that of the first overflowing holes.
Preferably, the second overflow aperture outlet axis is at an acute angle to a tangent of the suction surface to the trailing edge.
The invention also provides a centrifugal impeller which comprises any one of the hollow blades.
The hollow blade provided by the invention comprises a blade body, wherein a cavity penetrating through the blade body along the axial direction is formed in the blade body, a first overflowing hole is formed in the pressure surface of the blade body and is used for communicating the space above the blade body with the cavity, a second overflowing hole is formed in the suction surface of the blade body and is used for communicating the space below the suction surface with the cavity, part of gas on the pressure surface flows to the suction surface through the cavity, the gas velocity distribution in the boundary layer of the suction surface is changed, the fluid in the boundary layer can obtain kinetic energy, the friction resistance is overcome, the generation of backflow is avoided, and the vortex separation is restrained.
The cavity can slow down the speed of the airflow passing through the first overflowing hole and the second overflowing hole, so that the airflow can flow out of the suction surface at a lower and more uniform speed, and the influence of the airflow on the main airflow in the impeller flow passage is reduced. Meanwhile, the range of a low-speed area in the flow channel is reduced, and the speed gradient on the annular surface of the outlet of the impeller is reduced, so that the wake structure at the outlet of the centrifugal impeller is weakened, the pressure increase along the blades is more regular, and the efficiency of the impeller is improved.
In addition, in the prior art, the perforation position of the blade and the structure of the airflow hole need accurate numerical simulation for providing reference, and the numerical simulation has the disadvantages of complex calculation, large calculation amount and long calculation period, so that the design cost of the blade is high. The hollow blade provided by the invention is provided with the cavity, and the first overflowing hole and the second overflowing hole can be arranged in a staggered mode, so that the speed of adjusting airflow is reduced, the precision requirement of a punching position is reduced, and the calculation cost of numerical simulation is reduced.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
FIG. 1 is a schematic structural view of a hollow blade according to the present invention;
FIG. 2 is a schematic view of the distribution of hollow blades provided by the present invention;
fig. 3 is a schematic structural diagram of a centrifugal impeller provided by the present invention.
Wherein the reference numerals in fig. 1 to 3 are:
the pressure surface 1, the suction surface 2, the front edge 3, the rear edge 4, the first overflowing hole 11 and the second overflowing hole 21
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
Referring to fig. 1 to 3, fig. 1 is a schematic structural view of a hollow blade according to the present invention; FIG. 2 is a schematic view of the distribution of hollow blades provided by the present invention; fig. 3 is a schematic structural diagram of a centrifugal impeller provided by the present invention.
The hollow blade provided by the invention comprises a blade body, as shown in fig. 1, a cavity extending along the axial direction of the blade body is arranged in the blade body, a pressure surface 1 of the blade body is provided with a first overflowing hole 11, the first overflowing hole 11 penetrates through the pressure surface 1, and the cavity is communicated with a space above the pressure surface 1; the suction surface 2 of the blade body is provided with a second overflowing hole 21, and the second overflowing hole 21 penetrates through the suction surface 2 to communicate the cavity with the space below the suction surface 2. In the rotating process of the centrifugal impeller, the pressure of the air flow above the pressure surface 1 is high, the pressure of the air flow below the suction surface 2 is low, the adjusting air flow is formed between the first overflowing hole 11 and the second overflowing hole 21 under the action of pressure difference, the adjusting air flow flows along the curve in the figure 1, the air flow passes through the cavity from the outer side of the pressure surface 1 and flows into the outer side of the suction surface 2, the air flow speed distribution in the boundary layer of the suction surface 2 can be changed, fluid in the boundary layer can obtain kinetic energy, therefore, the friction resistance is overcome, the generation of backflow is avoided, and further vortex separation is restrained.
Alternatively, the cross section of the cavity may be circular, oval, airfoil, etc., wherein preferably the airfoil is formed, and the first and second overflow holes 11 and 21 may be circular holes, oval holes, petaloid perforations, or other shapes. The number of the first overflowing holes 11 and the second overflowing holes 21 can be multiple, so that the adjusted air flow is more uniform. The first overflowing hole 11 and the second overflowing hole 21 can be arranged in a staggered mode, so that gas passing through the first overflowing hole 11 cannot directly flow out of the second overflowing hole 21 to impact the main flow of the suction surface 2, and the adjusting effect of the cavity on the adjusting gas flow, namely the speed reducing effect and the uniform effect, are fully exerted. The offset arrangement means that the two are not located at the same radial position, i.e. the axes of the two are not located on the same line.
As shown in fig. 1, the cross section of the cavity is a wing shape, the blade body includes a first blade plate and a second blade plate, the first blade plate or the second blade plate is provided with a bending part bending backwards, and both the first blade plate and the second blade plate can be made by bending equal-thickness plates. The first blade plate and the second blade plate respectively form a pressure surface 1 and a suction surface 2, the bent part forms a front edge 3 of the blade body, and the rear parts of the first blade plate and the second blade plate are connected to form a tail edge 4 of the blade body. The first and second blades may be connected by welding, riveting or bolting.
In the embodiment, the hollow blade is provided with the cavity extending along the axial direction, the first overflowing hole 11 and the second overflowing hole 21 respectively communicate the cavity with the space on two sides of the blade body, when the hollow blade does work, the air flow is adjusted to pass through the cavity and flow into the suction surface 2 from the pressure surface 1 of the blade body, so that the fluid in the boundary layer obtains kinetic energy to flow to the tail edge 4 of the blade body, the generation of backflow is further avoided, the loss of the boundary layer is reduced, and the efficiency of the fan is improved.
Because the gas pressure in the flow passage is gradually increased from the front edge 3 to the tail edge 4, the distance between the first overflowing hole 11 and the tail edge 4 of the blade body is less than or equal to 1/3 of the length of the pressure surface 1, namely the first overflowing hole 11 is positioned in the area from the front edge 3 to two thirds of the length of the tail edge 4 to the tail edge 4 of the blade, the second overflowing hole 21 is positioned at the rear part of the suction surface 2 close to the tail edge 4, and the distance between the second overflowing hole 21 and the tail edge 4 is less than the distance between the first overflowing hole 11 and the tail edge 4, so that the gas pressure at the perforation structure of the pressure surface 1 is ensured to be greater than the gas pressure at the perforation structure of the suction surface 2.
In order to further reduce the velocity of the adjusting airflow and avoid the influence of the adjusting airflow on the main airflow, the area of all the first overflowing holes 11 is smaller than or equal to the area of all the second overflowing holes 21, and because the total area of the second overflowing holes 21 is larger than or equal to the total area of the first overflowing holes 11, the velocity of the adjusting airflow when the adjusting airflow flows out of the second overflowing holes 21 is smaller than the velocity when the adjusting airflow flows into the first overflowing holes 11.
The number of the second overflowing holes 21 is larger than that of the first overflowing holes 11, the diameter of the second overflowing holes 21 is smaller than that of the first overflowing holes 11, and all the second overflowing holes 21 are compact and fine round holes, so that the adjusting airflow can flow out more uniformly.
In addition, the influence of the adjusting airflow on the main airflow can be reduced by reducing the included angle between the adjusting airflow and the main airflow. Specifically, the main airflow flows from the front edge 3 to the tail edge 4 of the hollow blade, the speed direction of the main airflow is the same as the tangential direction of the suction surface 2 towards the tail edge 4, an acute angle is formed between the air outlet direction of the outlet of the second overflowing hole 21 and the tangential line of the suction surface 2 towards the tail edge 4, and the influence of the adjusted airflow on the main airflow can be reduced.
In this embodiment, the first overflowing hole 11 is located in the range of 1/3 lengths behind the pressure surface 1, the total area of the first overflowing hole 11 is smaller than or equal to the total area of the second overflowing hole 21, and the diameter of the first overflowing hole 11 is larger than that of the second overflowing hole 21, so that the velocity of the adjusting airflow entering below the suction surface 2 is low, and the interference of the adjusting airflow on the main airflow is reduced.
The invention also provides a centrifugal impeller, which comprises the hollow blades in any embodiment, the structure of the centrifugal impeller is shown in fig. 2 and 3, and the structures of the parts except the hollow blades can refer to the prior art and are not repeated herein.
It is noted that, in this specification, relational terms such as first and second, and the like are used solely to distinguish one entity from another entity without necessarily requiring or implying any actual such relationship or order between such entities.
The centrifugal impeller and the hollow blades thereof provided by the present invention are described in detail above. The principles and embodiments of the present invention are explained herein using specific examples, which are presented only to assist in understanding the method and its core concepts. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (5)
1. A hollow blade is characterized by comprising a blade body, wherein the blade body is provided with a cavity, a pressure surface (1) and a suction surface (2) of the blade body are respectively provided with a first overflowing hole (11) and a second overflowing hole (21), so that gas outside the pressure surface (1) can flow into the outside of the suction surface (2) through the cavity;
the distance between the first overflowing hole (11) and the tail edge (4) of the blade body is smaller than or equal to 1/3 of the length of the pressure surface (1), and the second overflowing hole (21) is located at the rear part of the suction surface (2);
the number of the second overflowing holes (21) is larger than that of the first overflowing holes (11), and the diameter of the second overflowing holes (21) is smaller than that of the first overflowing holes (11).
2. The hollow blade according to claim 1, wherein the blade body comprises a first blade and a second blade, which constitute the pressure side (1) and the suction side (2), respectively.
3. The hollow blade as claimed in claim 2, characterized in that the total area of the first flow-through openings (11) is smaller than or equal to the total area of the second flow-through openings (21).
4. The hollow blade according to any of claims 1 to 3, characterized in that the outlet axis of the second overflowing hole (21) forms an acute angle with the tangent of the suction surface (2) towards the trailing edge (4).
5. A centrifugal impeller comprising a hollow blade according to any one of claims 1 to 4.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810935033.3A CN109058157B (en) | 2018-08-16 | 2018-08-16 | Centrifugal impeller and hollow blade thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810935033.3A CN109058157B (en) | 2018-08-16 | 2018-08-16 | Centrifugal impeller and hollow blade thereof |
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| Publication Number | Publication Date |
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| CN109058157A CN109058157A (en) | 2018-12-21 |
| CN109058157B true CN109058157B (en) | 2020-11-10 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201810935033.3A Active CN109058157B (en) | 2018-08-16 | 2018-08-16 | Centrifugal impeller and hollow blade thereof |
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Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109973430B (en) * | 2019-05-08 | 2021-10-26 | 泛仕达机电股份有限公司 | Combined hollow wing blade |
| CN110374918B (en) * | 2019-07-31 | 2021-01-15 | 宁波方太厨具有限公司 | Impeller for centrifugal fan and control method thereof |
| CN112032109A (en) * | 2020-09-15 | 2020-12-04 | 中国航发沈阳发动机研究所 | Blade |
| CN112590379A (en) * | 2020-12-18 | 2021-04-02 | 无锡天辰技贸发展有限公司 | Thermoprinting mechanism of thermoprinting machine |
| CN115111189A (en) * | 2022-06-29 | 2022-09-27 | 广东顺威精密塑料股份有限公司 | Self-induction backward centrifugal fan blade |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB754055A (en) * | 1953-08-05 | 1956-08-01 | Westinghouse Electric Int Co | Improvements in or relating to centrifugal fan wheels |
| EP0807760B1 (en) * | 1996-05-17 | 2003-09-17 | Calsonic Kansei Corporation | Centrifugal multiblade fan |
| US8449249B2 (en) * | 2010-04-09 | 2013-05-28 | Williams International Co., L.L.C. | Turbine nozzle apparatus and associated method of manufacture |
| CN203453117U (en) * | 2013-08-20 | 2014-02-26 | 广东美的暖通设备有限公司 | Backward centrifugal wind wheel |
| CN204200676U (en) * | 2014-10-27 | 2015-03-11 | 安徽科达埃尔压缩机有限公司 | Centrifugal blower fan blade wheel |
| CN204610370U (en) * | 2015-04-22 | 2015-09-02 | 浙江理工大学 | A kind of centrifugal impeller of blade trailing edge perforation |
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