CN111828387A - Fan blade of large-flow low-speed fan - Google Patents

Fan blade of large-flow low-speed fan Download PDF

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Publication number
CN111828387A
CN111828387A CN202010830833.6A CN202010830833A CN111828387A CN 111828387 A CN111828387 A CN 111828387A CN 202010830833 A CN202010830833 A CN 202010830833A CN 111828387 A CN111828387 A CN 111828387A
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China
Prior art keywords
fan
blade
fan blade
area
flow
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CN202010830833.6A
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Chinese (zh)
Inventor
梁连国
桂幸民
吴光明
王佳算
姜春芳
梁惠娟
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Zhejiang Zhefeng Technology Co ltd
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Zhejiang Zhefeng Technology Co ltd
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Priority to CN202010830833.6A priority Critical patent/CN111828387A/en
Publication of CN111828387A publication Critical patent/CN111828387A/en
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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
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/38—Blades
    • F04D29/384—Blades characterised by form
    • F04D29/386—Skewed blades
    • 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
    • F04D29/02—Selection of particular materials
    • F04D29/023—Selection of particular materials especially adapted for elastic fluid pumps
    • 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
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/325—Rotors specially for elastic fluids for axial flow pumps for axial flow fans
    • 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
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/325—Rotors specially for elastic fluids for axial flow pumps for axial flow fans
    • F04D29/329—Details of the hub
    • 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
    • F04D29/32—Rotors specially for elastic fluids for axial flow pumps
    • F04D29/34—Blade mountings
    • 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
    • F04D29/666—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by means of rotor construction or layout, e.g. unequal distribution of blades or vanes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2300/00—Materials; Properties thereof
    • F05D2300/10—Metals, alloys or intermetallic compounds
    • F05D2300/17—Alloys
    • F05D2300/173—Aluminium alloys, e.g. AlCuMgPb

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structures Of Non-Positive Displacement Pumps (AREA)

Abstract

A fan blade of a large-flow low-speed fan comprises a hub sleeve, a fan blade, a fixed rod and a fixed bolt; the fan blades are rigidly connected with the fixed rods through the front end panel, the rear end panel and a plurality of fixed screws; the fan blade uses a U-shaped hoop to connect the fixed rod on the hub sleeve; the fan blade is straight in appearance, and the blade profile geometry of each cross section is the same, divide into three regions: the device comprises a front edge flow guide area, a middle pressurizing area and a tail edge flow rectifying area; the leading edge guide zone accounts for about 10 percent of chord length and can adapt to the relative airflow direction of the incoming flow under different linear speeds; the middle supercharging area is 50% chord length behind the leading edge flow guiding area, generates enough wind pressure rise through the geometric shape difference of the blade profile, and has the relative thickness not less than 15% so as to enable the fixing rod to be installed inside the middle supercharging area; the trailing edge rectifying area is about 40 percent of chord length at the rear part of the blade profile, and the geometric shape with small wedge angle and small curvature is adopted to reduce the static pressure difference and slow down the exhaust loss. The geometric coordinates of the blade profile surfaces of the three regions are generated by a plurality of polynomial functions.

Description

Fan blade of large-flow low-speed fan
[ technical field ] A method for producing a semiconductor device
The invention belongs to the field of fan application, and particularly relates to a fan blade of a high-flow low-speed fan, which is suitable for an axial flow type ventilation machine with the wind pressure lower than 300 Pa.
[ background of the invention ]
The failure patent 201020161228 hollow blade of fan discloses a fan blade, which is characterized in that the hollow blade is adopted, and the connection strength between the blade and the rotating shaft is enhanced.
For the fan blade, in addition to the above technology, the shape and structure of the aerodynamic performance of the blade are more important to determine, and are key design factors of the fan performance and energy efficiency. There are also enterprises that take reverse design to change their aerodynamic shape to circumvent the western patent, but are not aware of the same, so the resulting changes often severely degrade performance and do not provide an effective, self-designed product according to the needs of the user.
Traditionally, the high-flow low-speed fan adopts fan blades with equal-thickness blade profiles, the fan blades are twisted from a hub to a casing to adapt to the relative incoming flow direction, the fan is various, and various fans present unique personality due to different use objects and cannot form standard blade profiles to expand the application range. At present, fan blades with variable thickness blade profiles are widely applied to the field of axial flow type ventilation machinery, and the invention is a standard blade profile suitable for wind pressure lower than 300Pa formed through repeated design optimization and practical tests on the basis of long-term basic research.
The company has accumulated abundant manufacturing experience when engaged in fan design and manufacture for more than twenty years, is in close cooperation with universities and colleges, and makes great improvement and breakthrough on the fan blades of the high-flow low-speed fan. The scheme accordingly occurs.
[ summary of the invention ]
In order to improve the aerodynamic performance of the fan and overcome the defects of poor applicability, complex manufacturing and high cost of a large-flow low-speed fan in the current market, the invention provides the fan blade of the large-flow low-speed fan.
In order to achieve the purpose, the invention adopts the technical scheme that:
a fan blade of a large-flow low-speed fan comprises: the fan comprises a hub sleeve, fan blades, a fixed rod and a fixed bolt; the fan blades are uniformly arrayed on the hub sleeve in a radial shape through the fixing structure, the hub sleeve is rigidly fixed on a rotating shaft of the fan, the number of the fan blades can be 2-8 according to the requirements of air volume and air pressure, the fan blades are of a hollow structure, reinforcing ribs are arranged in the fan blades, and the fan blades are rigidly connected with the fixing rod through a front end panel, a rear end panel and a plurality of fixing screws; the fan blade fixing structure is a plurality of U-shaped hoops, and the fixing rod is connected to the hub sleeve by using the U-shaped hoops;
the fan blade is straight in appearance, the blade profile geometry of each section is completely the same, and the fan blade can be divided into three areas: the device comprises a front edge flow guide area, a middle pressurizing area and a tail edge flow rectifying area; the leading edge guide area accounts for about 10 percent of chord length and can adapt to the relative airflow direction of the incoming flow under different linear speeds; the middle supercharging area is 50% of chord length behind the leading edge flow guiding area, generates enough wind pressure rise through the geometric shape difference of the blade profile, and has the relative thickness not less than 15% so as to enable the fixing rod to be installed inside the middle supercharging area; the trailing edge rectifying area is about 40 percent of chord length at the rear part of the blade profile, and the geometric shape with small wedge angle and small curvature is adopted to reduce static pressure difference and slow down exhaust loss.
The geometric coordinates of the blade profile surfaces of the three regions are generated by a plurality of polynomial functions:
firstly, determining the geometry of the camber line which is suitable for the pneumatic effect by using the camber line bevel angle, generating a fourth-order polynomial fitting curve according to the designed camber line bevel angle, wherein the design formula is as follows:
α＝30.782c4-93.764c3+141.39c2-131.79c+33.3706
wherein c is the percentage chord length, and alpha is the camber line bevel angle;
secondly, calculating the coordinates of the mean camber line according to the bevel angle of the mean camber line to form a sextic polynomial curve, wherein the design formula is as follows:
y＝-3.8117×10-13c6+3.6398×10-10c5-1.4459×10-7c4+3.4525×10-5c3-6.7509×10-3c2+6.7714×10-1c-3.19373
wherein c is the percentage chord length, and y is the relative deflection of the mean camber line;
finally, the geometric coordinates of the blade profile surface are generated by the thickness distribution which is suitable for the aerodynamic rules of leading edge flow guiding, middle pressurizing, trailing edge rectifying and the like, and the design formula of the thickness distribution is as follows:
t＝-0.56403m6+2.1175m5-3.3814m4+3.2549m3-2.0297m2+0.58494m+0.021270
wherein m is the relative length of the mean camber line, and t is the relative half thickness.
As an optimization scheme, a front end panel and a rear end panel are arranged at two ends of the fan blade shell, and the peripheral contour lines of the front end panel and the rear end panel are matched with the peripheral contour line of the fan blade shell; the front panel is provided with a through hole for accommodating the fixed rod to pass through.
As an optimized scheme, the fan blade fixing structure comprises a plurality of U-shaped hoops and fixing rods; a plurality of annular grooves are formed in one side of the fixed rod, close to the hub sleeve, and the diameters of the annular grooves are matched with those of the U-shaped hoops; the fixed rod is fixed inside the fan blade shell by screws.
As an optimized scheme, the hub sleeve is provided with a plurality of semicircular grooves, and the radius of each semicircular groove is matched with the fixed rod of the fan blade; the number of the installed fan blades can be conveniently determined according to the using process.
As an optimized scheme, the hub sleeve is also provided with a plurality of through holes, so that the U-shaped hoop can conveniently penetrate through the through holes to tightly press the fixing rod on the hub sleeve; the key slot is arranged in the rotating shaft hole in the center of the hub sleeve, so that the hub sleeve can be conveniently fixed on a rotating shaft (not shown) of the fan.
As an optimized scheme, the fan blade is made of aluminum alloy or glass fiber reinforced plastic.
The invention has the following beneficial effects:
1. the blade profile which can adapt to a large attack angle range is adopted, the geometric shape of the blade is greatly simplified, the blade has more advanced pneumatic performance characteristics, and the formed standard blade is beneficial to high efficiency, low power consumption, low noise, corrosion resistance and high fatigue strength, and the manufacturing cost is reduced.
2. The hub is sleeved with a plurality of specifications, has different sizes and has different numbers of semicircular grooves; the fan blades rigidly arranged on the hub sleeve are replaceable and have various sizes and shapes; various combinations of the hub sleeve and the fan blades enable multi-specification standardization serialization of the fan to be implemented, various fan flow requirements are provided through changing of the diameter, the height difference and the number of the blades and scaling of the geometric shapes of the blades, and a user can freely select the optimal fan diameter according to the application.
3. The connection between the fan blade and the hub sleeve allows the angle of the fan blade to be partially adjusted, which is beneficial to simply and conveniently adjusting dynamic balance.
4. The fan blades have fixed geometric shapes and cannot be twisted under ultra-strong wind pressure.
[ description of the drawings ]
FIG. 1 is a schematic view of the general assembly of a fan blade according to the present invention;
fig. 2 is a schematic view of the back of the general assembly of the fan blade;
FIG. 3 is a schematic view of a fan blade component;
FIG. 4 is an exploded view of a fan blade structure;
fig. 5 is a schematic sectional view of a new blade profile (H is the maximum thickness and C is the chord length).
FIG. 6 is a cross-sectional view of an old fan blade in the prior art;
FIG. 7 is a comparison of blade profiles of the new and old blades of the present invention;
FIG. 8 is the calculation results of the full pressure characteristic curve of example 2;
FIG. 9 is a static pressure rise characteristic curve calculation result of example 2;
FIG. 10 shows the calculation results of the efficiency characteristics of example 2;
FIG. 11 shows the calculation results of the power characteristics of example 2;
FIG. 12 is the calculation results of the full pressure characteristic curve of example 3;
FIG. 13 is a static pressure rise characteristic curve calculation result of example 3;
FIG. 14 shows the calculation results of the efficiency characteristics of example 3;
FIG. 15 shows the calculation results of the power characteristics of example 3;
FIG. 16 is a full pressure characteristic curve of example 3 with different steps;
FIG. 17 is an efficiency characteristic curve in different steps of example 3.
Reference numerals:
1. a hub sleeve; 1.1 semicircular groove and 1.2 rotating shaft holes.
2. A fan blade; 2.1 fan blade casing, 2.1.1 strengthening rib, 2.2 wheel hub end panel, 2.2.1 dead lever through-hole, 2.3 blade top end panel, 2.3.1 front edge, 2.3.2 front edge diversion district, 2.3.3 middle part pressure boost area, 2.3.4 suction surface, 2.3.5 dead lever position, 2.3.6 trailing edge, 2.3.7 pressure face, 2.3.8 trailing edge rectification district.
3. Fixed rod, 3.1 ring groove.
A U-shaped hoop.
5. And a screw component.
6. A new fan blade.
7. Old fan blades.
[ detailed description ] embodiments
The technical solution of the present invention will be further described in detail with reference to the accompanying drawings and examples.
A blade of a high-flow low-speed fan mainly comprises a standard blade type fan blade and a fan assembly. Because a certain blade profile geometry is required to adapt to the convection fields of the wind turbines with different blade heights, different flow rates and different wind pressures, the blade must adapt to a large attack angle range, and meanwhile, in order to ensure that a pull rod for tensioning and fixing the blade has enough strength, the blade profile geometry of the blade adopts a pneumatic design different from the traditional geometric shape. The design characteristics include: leading edge flow guiding region 2.3.2, middle booster region 2.3.3 and trailing edge fairing 2.3.8 are generated from three polynomial function curves. The leading edge guide area 2.3.2 not only adapts to the direction of the incoming flow by using the leading edge 2.3.1, but also adapts to the change of the attack angle in a large range by using the leading edge guide area with about 10 percent of chord length, so that the low-loss attack angle range is increased, and the adaptability to the direction of the incoming flow is expanded; the gentle pressure surface 2.3.7 makes the air current entering the blower slow down, make its surface static pressure rise consistently, and the suction surface 2.3.4 accelerates sharply at the front, make the surface static pressure reach the maximum in the area of maximum thickness H, thus has formed the huge pressure difference of the pressure surface 2.3.7 and suction surface 2.3.4, form the middle pressurized area with front loading characteristic, the energy input static pressure potential energy of the impeller is mainly finished in this area, produce the sufficient wind pressure through the geometric shape difference of the blade profile to rise; about 40% of the chord length at the trailing edge of the airfoil is the trailing edge fairing 2.3.8 which acts to slow the static pressure rise at the pressure face 2.3.7, while the static pressure at the suction face 2.3.4 is still linearly increasing, providing a balanced static pressure at the flow to the trailing edge 2.3.6 to reduce the trailing edge at the exit of the airfoil. Because the aerodynamic structure characteristics of small wedge angle and small curvature of the trailing edge rectifying region 2.3.8 are effectively utilized, the trailing edge 2.3.6 can be in a square or triangular geometric shape and the like, and the requirement on the manufacturing precision of the trailing edge is effectively reduced; since the pressure surface 2.3.7 has a relatively low flow velocity, its friction losses are not decisive for the efficiency and the manufacturing accuracy can be reduced.
Example 1
As shown in fig. 1 to 5, a fan blade of a high-flow low-speed fan comprises: the hub sleeve 1 and the fan blade 2; in the embodiment, 4 fan blades 2 are uniformly arrayed on a hub sleeve 1 in a radial shape, and the hub sleeve 1 is fixed on a rotating shaft of a fan; the fan blade shell 2.1 is hollow, and a reinforcing rib 2.1.1 is arranged in the middle. The fan blade shell 2.1 is straight and straight in appearance, and the cross sections of all the positions are the same in size; the fan blade shell 2.1 is rigidly connected with the fixed rod through a front end panel, a rear end panel and a plurality of screw parts 5, and the fixed rod 3 is connected on the hub sleeve 1 by using a U-shaped hoop 4; the maximum thickness H area is positioned at the position of 20-30% chord length of the blade profile, and the thickness is larger than 116% of the diameter of the fixed rod, so that enough space can be ensured inside the blade profile to place the fixed rod, and the blade profile has definite front loading aerodynamic geometric characteristics.
In this embodiment, the fan blade is made of aluminum alloy. The two ends of the fan blade shell 2.1 are provided with a front end panel 2.2 and a rear end panel 2.3, and the peripheral contour lines of the front end panel 2.2 and the rear end panel 2.3 are matched with the peripheral contour line of the fan blade shell 2.1. The fixed rod 3 is provided with 2 annular grooves 3.1 on one side close to the hub sleeve 1, and the diameters of the annular grooves 3.1 are matched with the U-shaped hoops 4.
In the embodiment, the hub sleeve 1 is provided with 8 semicircular grooves 1.1, and the radius of the semicircular grooves is matched with the radius of a fixed rod 3 of a fan blade 2; the number of the semicircular grooves 1.1 exceeds the number of the fan blades 2, so that when 2, 4 or 8 fan blades are installed according to the using process, the hub sleeve does not need to be replaced. Similarly, if 6 semicircular grooves 1.1 are uniformly arrayed, 3 blades 2 can be installed on the same hub sleeve 1, and 6 blades 2 can also be installed on the same hub sleeve.
The hub sleeve 1 is also provided with a plurality of through holes 1.3, so that the U-shaped hoop 4 can conveniently penetrate through the through holes 1.3 to tightly press the fixing rod on the hub sleeve 1; a key groove is arranged in the central rotating shaft hole 1.2, so that the hub sleeve 1 can be conveniently fixed on a rotating shaft (not shown) of the fan.
Referring to fig. 6, the old fan blade in the prior art is defined as follows: the chord length of the blade profile is 231.85mm, the maximum thickness is 37.55mm, and the maximum relative thickness is 16.2%. As can be clearly seen by comparing with the new blade type shown in fig. 7 of the invention, the old blade is a typical modern airplane airfoil shape and has the characteristic of high lift loaded at the trailing edge, while the new blade type is a typical impeller blade type and has the characteristic of controllable diffusion pressurization. Both differ clearly from the aerodynamic principle to the structural form.
Another advantage of the new blade profile of the present invention is the forward maximum thickness, which is also a common feature of modern subsonic blade profiles. The characteristic enables the fan blade to have wider flow adaptability. Because of the capability, the equal-geometry blade profiles can be stacked into the fan blades along a straight line to form low-speed impellers which can adapt to the change of the attack angle under different radiuses, so that a universal standard blade profile is formed, a large flow range is adapted, and the manufacturing cost is reduced.
The advantages are revealed, the defects are avoided, and the front loading blade profile with more modern characteristics is formed on the premise of not reducing the application range and saving the manufacturing cost, so that the new blade profile has the characteristics of independent intellectual property in the real sense. The surface contour line geometry of the fresh air blade of the embodiment refers to the attached drawing 5, the maximum thickness and the relative position of the fresh air blade are changed, and the size of a fixed rod for fixing the fan blade can be guaranteed to be unchanged. Besides camber line curvature, the new blade type keeps the advantages of the original blade type before the maximum thickness, the camber line curvature of the blade type is enhanced after the maximum thickness, the effective pneumatic load is preposed, the straightness and a smaller wedge angle of the blade type are kept in a tail edge arrangement area, and the influence range of the pressure balance of a suction pressure surface to reduce the tail trace is facilitated. The tail edge geometry of the invention is no longer a key parameter, and the forming difficulty and the precision requirement of the thin-wall part are reduced.
Example 2
The parameters of the impeller of the embodiment 2 of the invention are as follows:
Figure BDA0002637907880000061
the original blade type and the new blade type fan blades are compared through numerical simulation, and fig. 8 to 11 are characteristic curves of full pressure, static pressure, efficiency and power changing along with flow respectively. For comparability, the same inlet metal angle is adopted for the two, namely the original blade profile (height difference 82.7) and the new blade profile (height difference 91.7) in the figure have the same inlet metal angle, and the original blade profile (height difference 97.4) and the new blade profile (height difference 106.3) have the same inlet metal angle.
The simulation results show that: the new blade profile maintains the characteristic that the total static pressure and the static pressure are improved compared with the original blade profile, and the new blade profile has stronger high supercharging capacity under different height difference conditions, which is consistent with the design of front load. Therefore, the new blade profile can meet the pressure rise requirement more easily in the application process.
The efficiency is on the left side of the peak efficiency no matter whether the blade is an original blade type or a new blade type, which shows that the fan blade has better large flow characteristic. The efficiency of the new blade profile is relatively low in the low-flow section, and the new blade profile has higher efficiency in the high-flow region, which shows that the new blade profile is more suitable for low-load application with smaller height difference, and the negative attack angle characteristic is more excellent, which is consistent with the general characteristic of the front loading blade profile. The smoothness and consistency of the power characteristics provide convenience for motor selection, and the motor is almost in the equal-power characteristic in the altitude difference debugging process.
Example 3
The parameters of the impeller in the embodiment 3 of the invention are as follows:
Figure BDA0002637907880000071
the original blade profile and the new blade profile are also compared by numerical simulation, and fig. 12 to 15 are characteristic curves of full pressure, static pressure, efficiency and power variation with flow rate, respectively. For comparability, the same inlet metal angle is adopted for both, namely the original blade profile (height difference of 110mm) and the new blade profile (height difference of 118.5mm) in the figure have the same inlet metal angle. The simulation results also feature example 2, i.e. the new blade profile maintains a higher total, static pressure lift capacity over the full flow range (fig. 12, 13), and at high flow rates the new blade profile has a higher efficiency (fig. 14). For design flow 50000m3The full pressure achieved by the original leaf type is 204.5Pa, while the new leaf type is 249Pa, which is much higher than the design requirement of 205 Pa. For the new leaf type, 56000m3The pressure rise requirement of 205Pa is met below/h, which shows that even if the diameter of the fan is reduced to a certain extent, the expected flow and pressure rise can be achieved, and the fan is certainly more compact and efficient, and is beneficial to reducing power and saving material cost.
The total pressure and efficiency characteristics according to the flow rate obtained by numerical simulation are shown in FIGS. 16 and 17 herein (in the figures, pt110 is the original type and the height difference is 110 mm; m is the new type and the height difference is 110mm to 130 mm) by changing the new type height difference of example 3. The results show that the height difference (m130) of the new leaf type 130mm is less than 50000m3The stall at flow/h is the maximum height difference of the inventive airfoil in example 3, the height difference is a usable solution from 118mm to 130mm, and the efficiency shows a tendency to rise (fig. 17). The new blade profile has a wide altitude difference adjusting range, which is closely related to the invention point of the blade profile.
Meanwhile, the fan number 12 of example 3 can be improved to the fan number 11 by adjusting the height difference, and the flow and the pressure rise are kept unchanged, while the power requirement can be further reduced by the obvious increase of the efficiency. These advantageous features all result from the aerodynamic profile of the blade that the invention is intended to protect.
Through the change of the loading mode, the blade profile of a certain type of low-speed low-load impeller is newly designed, the performance characteristics of new and old fan blades are calculated and compared under two operating conditions with different height differences, and the result of three-dimensional numerical simulation shows that the new fan blade has better application advantages.
The new blade profile is suitable for impellers with the diameter of more than 1000mm, and the impeller with the too small diameter can be reduced according to the chord length, so that whether the application requirements are worthy of improvement or not needs to be met, but the geometric integrity of the blade profile contour line is not easily changed.
The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents or modifications made within the design principles of the present invention, such as trailing edge cutting, thickness variation, geometric shape change, fixing rod change from circular to sheet, material replacement, etc., are all considered to be derivatives of the leaf-shaped technology of the present invention, and are all covered by the protection scope of the present invention.

Claims (6)

1. The utility model provides a fan blade of large-traffic low-speed fan, includes wheel hub cover, fan blade, and a plurality of fan blades are the even array of radial form through fixed knot structure and sheathe in at wheel hub, and the wheel hub cover is fixed on the fan pivot, and fan blade quantity is 2-8, and the fan blade casing is hollow, and the centre has strengthening rib, its characterized in that: the fan blade is straight and straight in appearance, and the cross sections at all positions are the same in size; the fan blade is rigidly connected with the fixed rod through a front end panel, a rear end panel and a plurality of screw components, the fan blade fixing structure is a plurality of U-shaped hoops, and the fixed rod is connected on the hub sleeve by the U-shaped hoops;
the fan blade is straight in appearance, the blade profile geometry of each section is completely the same, and the fan blade can be divided into three areas: the device comprises a front edge flow guide area, a middle pressurizing area and a tail edge flow rectifying area; the leading edge guide area accounts for about 10 percent of chord length and can adapt to the relative airflow direction of the incoming flow under different linear speeds; the middle supercharging area is 50% of chord length behind the leading edge flow guiding area, generates enough wind pressure rise through the geometric shape difference of the blade profile, and has the relative thickness not less than 15% so as to enable the fixing rod to be installed inside the middle supercharging area; the trailing edge rectifying area is about 40 percent of chord length at the rear part of the blade profile, and the static pressure difference is reduced by adopting a small wedge angle and a small curvature geometric shape, so that the exhaust loss is reduced;
the geometric coordinates of the blade profile surfaces of the three regions are generated by a plurality of polynomial functions, the camber line geometry which is suitable for the pneumatic effect is determined by the camber line bevel angle, a fourth-order polynomial fitting curve is generated according to the designed camber line bevel angle, and the design formula is as follows: 30.782c4-93.764c3+141.39c2-131.79c +33.3706, wherein c is the percent chord length and α is the mean camber angle;
secondly, calculating the coordinates of the mean camber line according to the bevel angle of the mean camber line to form a sextic polynomial curve, wherein the design formula is as follows:
y＝-3.8117×10-13c6+3.6398×10-10c5-1.4459×10-7c4+3.4525×10-5c3-6.7509×10- 3c2+6.7714×10-1c-3.19373
wherein c is the percentage chord length, and y is the relative deflection of the mean camber line;
finally, the geometric coordinates of the blade profile surface are generated by the thickness distribution which is suitable for the aerodynamic rules of leading edge flow guiding, middle pressurizing, trailing edge rectifying and the like, and the design formula of the thickness distribution is as follows:
t＝-0.56403m6+2.1175m5-3.3814m4+3.2549m3-2.0297m2+0.58494m+0.021270
wherein m is the relative length of the mean camber line, and t is the relative half thickness.
2. The fan blade of the large-flow low-speed fan according to claim 1, characterized in that: the two ends of the fan blade shell are provided with a front end panel and a rear end panel, and the peripheral contour lines of the front end panel and the rear end panel are matched with the peripheral contour line of the fan blade shell; the front panel is provided with a through hole for accommodating the fixed shaft to pass through.
3. The fan blade of the large-flow low-speed fan according to claim 1, characterized in that: the fan blade fixing structure comprises a plurality of U-shaped hoops and fixing rods; and a plurality of annular grooves are formed in one side of the fixed shaft close to the hub sleeve, and the diameters of the annular grooves are matched with those of the U-shaped hoops.
4. The fan blade of the large-flow low-speed fan according to claim 1, characterized in that: the hub sleeve is provided with a plurality of semicircular grooves, and the radius of the semicircular grooves is matched with the fixed shaft of the fan blade.
5. The fan blade of the large-flow low-speed fan according to claim 1, characterized in that: the hub sleeve is also provided with a plurality of through holes; a key groove is arranged in the central rotating shaft hole.
6. The fan blade of the large-flow low-speed fan according to claim 1, characterized in that: the fan blades are made of aluminum alloy or glass fiber reinforced plastic.
CN202010830833.6A 2020-08-18 2020-08-18 Fan blade of large-flow low-speed fan Pending CN111828387A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112576546A (en) * 2020-12-15 2021-03-30 华中科技大学 Optimization method of non-uniform-thickness airfoil axial flow blade

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112576546A (en) * 2020-12-15 2021-03-30 华中科技大学 Optimization method of non-uniform-thickness airfoil axial flow blade

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