CN111828387B - A fan blade of a large flow and low speed fan - Google Patents
A fan blade of a large flow and low speed fan Download PDFInfo
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- CN111828387B CN111828387B CN202010830833.6A CN202010830833A CN111828387B CN 111828387 B CN111828387 B CN 111828387B CN 202010830833 A CN202010830833 A CN 202010830833A CN 111828387 B CN111828387 B CN 111828387B
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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
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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
- F04D29/02—Selection of particular materials
- F04D29/023—Selection of particular materials especially adapted for elastic fluid pumps
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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
- F04D29/325—Rotors specially for elastic fluids for axial flow pumps for axial flow fans
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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
- F04D29/325—Rotors specially for elastic fluids for axial flow pumps for axial flow fans
- F04D29/329—Details of the hub
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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
- F04D29/34—Blade mountings
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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
- F04D29/666—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
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- 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
一种大流量低速风机的风叶，包括轮毂套、风叶、固定杆和固定螺栓；风叶通过前端面板、后端面板和若干固定螺丝与固定杆刚性连接；风叶使用U形箍将固定杆连接在轮毂套上；风叶外形平直，各截面的叶型几何相同，分为三个区域：前缘导流区、中部增压区和尾缘整流区；前缘导流区约占10％弦长，能够适应不同线速度下来流的相对气流方向；中部增压区是继前缘导流区之后的50％弦长，通过叶型几何外形差异产生足够的风压上升，并具有不小于15％的相对厚度，以使其内部能够安装固定杆；尾缘整流区为叶型后部约40％弦长，采用小楔形角、小曲率几何外形以使静压差减小，减缓排气损失。所述三个区域的叶型表面几何坐标由多个多项式函数生成。
A fan blade of a large-flow low-speed fan comprises a hub sleeve, a fan blade, a fixing rod and a fixing bolt; the fan blade is rigidly connected to the fixing rod through a front panel, a rear panel and a plurality of fixing screws; the fan blade uses a U-shaped hoop to connect the fixing rod to the hub sleeve; the fan blade has a straight shape, and the blade geometry of each section is the same, and is divided into three areas: a leading edge guide area, a middle supercharging area and a trailing edge straightening area; the leading edge guide area accounts for about 10% of the chord length, and can adapt to the relative airflow direction of the flow at different linear speeds; the middle supercharging area is 50% of the chord length after the leading edge guide area, and generates sufficient wind pressure rise through the difference in blade geometry, and has a relative thickness of not less than 15% so that the fixing rod can be installed inside; the trailing edge straightening area is about 40% of the chord length of the rear part of the blade, and adopts a small wedge angle and a small curvature geometry to reduce the static pressure difference and slow down the exhaust loss. The blade surface geometric coordinates of the three areas are generated by multiple polynomial functions.
Description
[ Field of technology ]
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 air pressure lower than 300 Pa.
[ Background Art ]
The failure patent 201020161228 discloses a fan blade of a hollow fan, which is characterized in that the hollow fan blade is adopted, and the connection strength between the fan blade and a rotating shaft is enhanced.
For fan blades, besides the above technology, it is more important to determine the shape and structure of the aerodynamic performance of the fan blade, which is a key design factor of fan performance and energy efficiency. There are also enterprises that adopt reverse designs to change their aerodynamic shape in order to circumvent western patents, but are known to be unaware of this, and the changes made thereby often result in severe performance degradation and are not able to provide an effective, self-designed product according to the needs of the user.
Conventionally, such a high-flow low-speed fan adopts a fan blade with a uniform thickness blade profile, the fan blade must be twisted from a hub to a casing to adapt to the relative incoming flow direction, the fan is various in variety, and various fans show unique individuality due to different using objects, so that the standard blade profile cannot be formed to expand the application range. At present, the variable-thickness blade profile fan blade is widely applied to the field of axial-flow type ventilation machinery, and the standard blade profile suitable for the air pressure lower than 300Pa is formed by repeated design optimization and practical tests on the basis of long-term basic research.
The fan is designed and manufactured by the company for more than twenty years, so that rich manufacturing experience is accumulated, the fan is closely cooperated with universities and colleges, and great improvement and breakthrough are carried out on the fan blade of the high-flow low-speed fan. The present case therefore occurs.
[ Invention ]
In order to improve the aerodynamic performance of a fan and solve the defects of poor applicability, complex manufacture and high cost of a high-flow low-speed fan in the current market, the invention provides a fan blade of the high-flow low-speed fan.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
The fan blade of the high-flow low-speed fan comprises a hub sleeve, fan blades, a fixing rod and fixing bolts, wherein a plurality of fan blades are uniformly arranged on the hub sleeve in a radial shape through a fixing structure, the hub sleeve is rigidly fixed on a fan rotating shaft, the number of the fan blades can be selected to be 2-8 according to the requirements of air quantity and air pressure, the fan blades are of hollow structures, 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 blade profile of each section is flat and straight, the blade profile geometry of each section is completely the same and can be divided into three areas, namely a front edge flow guiding area, a middle pressurizing area and a tail edge rectifying area, wherein the front edge flow guiding area occupies 10% of the chord length and can adapt to the relative airflow directions of incoming flows under different linear speeds, the middle pressurizing area is 50% of the chord length after the front edge flow guiding area, sufficient wind pressure rising is generated through the blade profile geometry difference and has a relative thickness of not less than 15%, so that a fixed rod can be installed in the blade profile, the tail edge rectifying area is 40% of the chord length at the rear part of the blade profile, and the tail edge rectifying area adopts a small wedge angle and a small curvature geometry to reduce static pressure difference and slow down exhaust loss.
The three regions of leaf surface geometry are generated by a plurality of polynomial functions:
firstly, determining the mean camber line geometry adapting to the pneumatic effect by using the mean camber line bevel angle, generating a fourth-time polynomial fitting curve according to the designed mean 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 percent chord length, and alpha is the mean camber line oblique angle;
Secondly, calculating a mean camber line coordinate according to the mean camber line bevel angle to form a six-degree polynomial curve, wherein the design formula is as follows:
y=-3.8117×10-13c6+3.6398×10-10c5-1.4459×10-7c4+3.4525
x 10 -5c3-6.7509×10-3c2+6.7714×10-1 c-3.19373, wherein c is the percent chord length and y is the camber line relative deflection;
finally, generating geometrical coordinates of the blade profile surface by thickness distribution adapting to the front edge flow guiding, middle pressurizing and tail edge rectifying aerodynamic rules, wherein a thickness distribution design formula 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, the two ends of the fan blade shell are provided with a front end panel and a rear end panel, 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, and the front end panel is provided with a fixing rod through hole for accommodating the fixing rod to pass through.
The fan blade fixing structure is characterized by comprising a plurality of U-shaped hoops and a fixing rod, wherein one side of the fixing rod, which is close to the hub sleeve, is provided with a plurality of annular grooves, the diameters of the annular grooves are matched with the U-shaped hoops, and the fixing rod is fixed inside the fan blade shell by screws.
As an optimization scheme, if semicircular grooves are formed in the hub sleeve, the radius of the semicircular grooves is matched with the fixing rods of the fan blades, and the number of the installed fan blades can be conveniently determined according to the using process.
As an optimization scheme, the hub sleeve is further provided with a plurality of through holes, the U-shaped hoops penetrate through the through holes to press the fixing rods on the hub sleeve conveniently, and a key slot is arranged in a rotating shaft hole in the center of the hub sleeve to fix the hub sleeve on a fan rotating shaft (not shown).
As an optimization scheme, the fan blade is made of aluminum alloy or glass fiber reinforced plastic.
The invention has the following beneficial effects:
1. the adoption of the blade profile which can adapt to a large attack angle range greatly simplifies the geometric shape of the blade and 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 reduces the manufacturing cost.
2. The hub sleeve has various specifications, different sizes and different numbers of semicircular grooves, the fan blades rigidly mounted on the hub sleeve are changeable, and have various sizes and various shapes, and various combinations of the hub sleeve and the fan blades enable the standardization and serialization of the fan to be implemented, and various fan flow requirements are provided through the change of diameters, height differences and blade numbers and the scaling of blade geometric shapes, so that a user can freely select the optimal fan diameter according to the application.
3. The connection of the fan blade and the hub sleeve allows the local adjustment of the fan blade angle, which is beneficial to the simple and convenient adjustment of dynamic balance.
4. The fan blade has a fixed geometric shape and cannot twist under super-strong wind pressure.
[ Description of the drawings ]
FIG. 1 is a schematic view of the present invention a fan blade total assembly schematic diagram;
FIG. 2 is a schematic view of the back of a fan blade assembly;
FIG. 3 is a schematic view of a fan blade assembly;
FIG. 4 is an exploded view of a fan blade structure;
FIG. 5 is a schematic cross-sectional view of fresh air She Shexing (H is the maximum thickness, and C is the chord length).
FIG. 6 is a cross-sectional view of an old fan blade of the prior art;
FIG. 7 is a diagram showing the comparison of the profile sections of the new and old blades of the present invention;
FIG. 8 is the calculation result of the full pressure characteristic curve of example 2;
FIG. 9 is a graph showing the calculation result of the hydrostatic lift characteristic curve in example 2;
FIG. 10 is a graph showing the calculation result of the efficiency characteristic curve of example 2;
FIG. 11 is a graph showing the power characteristic curve calculation result of example 2;
FIG. 12 is the calculation result of the full pressure characteristic curve of example 3;
FIG. 13 is a graph showing the calculation result of the hydrostatic lift characteristic curve in example 3;
FIG. 14 is a graph showing the calculation result of the efficiency characteristic curve of example 3;
fig. 15 is a power characteristic curve calculation result of example 3;
FIG. 16 is a graph showing the full pressure characteristic at different level differences in example 3;
FIG. 17 is a graph showing the efficiency characteristic of the difference in level of example 3.
Reference numerals:
1. 1.1 semicircle groove, 1.2 rotation shaft hole, 1.3 through hole.
2. The fan blade comprises a fan blade shell, a 2.1.1 reinforcing rib, a 2.2 hub end plate, a 2.2.1 fixing rod through hole, a 2.3 blade top end plate, a 2.3.1 front edge, a 2.3.2 front edge flow guiding area, a 2.3.3 middle pressurizing area, a 2.3.4 suction surface, a 2.3.5 fixing rod position, a 2.3.6 tail edge, a 2.3.7 pressure surface and a 2.3.8 tail edge rectifying area.
3. And 3.1 annular grooves.
4.U-shaped hoops.
5. A screw member.
6. New fan blade.
7. Old fan blades.
[ Detailed description ] of the invention
The technical scheme of the invention is further described in detail below 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 determined blade profile geometry is needed to adapt to the fan relative flow fields of different blade heights, different flow rates and different wind pressures, the blades must adapt to a large attack angle range, and meanwhile, in order to ensure that a pull rod for tensioning the fixed blades has enough strength, the blade profile geometry of the blades adopts a pneumatic design different from the past geometry. The design characteristics of the device comprise that a leading edge diversion area 2.3.2, a middle pressurizing area 2.3.3 and a trailing edge rectifying area 2.3.8 are generated by three polynomial function curves. The leading edge flow guiding area 2.3.2 not only adapts to the direction of incoming flow by utilizing the leading edge 2.3.1, but also adapts to a large range of attack angle change by the leading edge flow guiding area with the chord length of about 10%, the low-loss attack angle range is increased, the adaptability to the direction of incoming flow is expanded, the gentle pressure surface 2.3.7 slowly decelerates the airflow entering the fan, the surface static pressure of the air flow is uniformly increased, the suction surface 2.3.4 is rapidly accelerated at the front, the surface static pressure is maximized in the area with the maximum thickness H, a huge pressure difference of the pressure surface 2.3.7 and the suction surface 2.3.4 is formed, a middle pressurizing area with a front loading characteristic is formed, the static pressure potential energy conversion of impeller energy input is mainly completed in the area, the sufficient wind pressure is generated by the geometrical shape difference of the blade shape, the chord length of about 40% at the rear part of the blade shape is the trailing edge rectifying area 2.3.8, the static pressure of the pressure surface 2.3.7 is gradually increased, the static pressure of the suction surface 2.3.4 is still increased in a linear way, and the static pressure of the suction surface is enabled to reach the tail edge 2.3.6, and the tail edge has a balanced static pressure trace of the blade shape. The pneumatic structural characteristics of small wedge angle and small curvature of the tail edge rectifying area 2.3.8 are effectively utilized, the tail edge 2.3.6 can be in square or triangular geometric shapes, the requirement on the manufacturing precision of the tail edge is effectively reduced, and the friction loss of the pressure surface 2.3.7 has relatively low flow speed, so that the friction loss is not decisive for the efficiency, and the manufacturing precision can be reduced.
Example 1
As shown in figures 1 to 5, the fan blade of the high-flow low-speed fan comprises a hub sleeve 1 and fan blades 2, in the embodiment, 4 fan blades 2 are uniformly arranged on the hub sleeve 1 in a radial mode, the hub sleeve 1 is fixed on a fan rotating shaft, a fan blade shell 2.1 is hollow, and a reinforcing rib 2.1.1 is arranged in the middle of the fan blade shell. The fan blade shell 2.1 is straight in appearance and identical in section size, the fan blade shell 2.1 is rigidly connected with a fixed rod through a front end panel, a rear end panel and a plurality of screw parts 5, the fixed rod 3 is connected to the hub sleeve 1 through a U-shaped hoop 4, the maximum thickness H area is positioned at the chord length position of 20-30% of the blade profile, and the thickness is larger than 116% of the diameter of the fixed rod, so that enough space can be reserved inside the blade profile, and the fan blade shell has definite front loading pneumatic 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 identical to the peripheral contour lines of the fan She Keti 2.1.1. The side of the fixed rod 3 close to the hub sleeve 1 is provided with 2 annular grooves 3.1, and the diameter of the annular grooves 3.1 is matched with that of the U-shaped hoop 4.
In this embodiment, 8 semicircular grooves 1.1 are provided on the hub sleeve 1, the radius of which is adapted to the radius of the fixing rod 3 of the fan blade 2, and the number of the semicircular grooves 1.1 exceeds the number of the fan blade 2, so that the hub sleeve does not need to be replaced when 2,4 or 8 fan blades are installed according to the use process. Similarly, if 6 semicircular grooves 1.1 are uniformly arrayed, the same hub sleeve 1 can be provided with 3 blades 2 or 6 blades 2.
The hub sleeve 1 is also provided with a plurality of through holes 1.3, so that the U-shaped hoop 4 can conveniently pass through the through holes 1.3 to press the fixing rod on the hub sleeve 1, and a key slot is arranged in the central rotating shaft hole 1.2, so that the hub sleeve 1 can be conveniently fixed on a fan rotating shaft (not shown).
The old fan blade in the prior art is defined as a blade profile chord length 231.85mm, a maximum thickness of 37.55mm and a maximum relative thickness of 16.2% referring to figure 6. As can be clearly seen from a comparison of the novel airfoil of FIG. 7 of the present invention, the old fan blade is a typical modern aircraft airfoil with trailing edge loading high lift features, whereas the present invention is a typical turbine airfoil with controlled diffusion boost features. There is a clear difference between the two from the aerodynamic principle to the structural form.
Another advantage of the new airfoil of the invention is the prepositioning of maximum thickness, which is also a common feature of modern subsonic airfoils. The fan blade has wider flow adapting capability. Because of the capability, the uniform geometric blade profile can be adopted to be stacked into the fan blade along a straight line, so that the low-speed impeller which can adapt to the change of the attack angle under different radiuses is formed, the universal standard blade profile is suitable for a large flow range, and the manufacturing cost is reduced.
The method has the advantages of avoiding the defects, forming a front loading leaf profile with more modern characteristics on the premise of not reducing the application range and saving the manufacturing cost, and enabling the new leaf profile to have true independent intellectual property characteristics. In this embodiment, when the surface contour line of the fresh air blade is geometrically referred to fig. 5, the maximum thickness and the relative position thereof are all changed, so that the size of the fixing rod for fixing the fan blade is unchanged. Besides the camber line camber, the new blade profile maintains the advantageous characteristics of the original blade profile before the maximum thickness, strengthens the camber line camber of the blade profile after the maximum thickness, enables the effective pneumatic load to be prepositioned, maintains the straightness and smaller wedge angle of the blade profile in the tail edge finishing area, and is beneficial to balancing the pressure of the suction pressure surface so as to reduce the influence range of wake. The tail edge geometry of the invention is not a key parameter any more, and the molding difficulty and the precision requirement of the thin-wall part are reduced.
Example 2
The impeller parameters of embodiment 2 of the present invention are:
volume flow is 74300m 3/h;
The rotation speed is 480rpm;
diameter is 1800mm;
blade chord length 231.5mm;
6, the number of blades;
Tip clearance 9mm;
atmospheric temperature 293.15K (i.e., 20 ℃);
atmospheric pressure is 100813.7Pa.
The original blade profile and the new blade profile are compared through numerical simulation, and fig. 8 to 11 are characteristic curves of full pressure, static pressure, efficiency and power along with the change of flow respectively. For comparability, the same inlet metal angles are used for both, i.e. the original profile (height difference 82.7) and the new profile (height difference 91.7) in the figure have the same inlet metal angle, and the original profile (height difference 97.4) and the new profile (height difference 106.3) have the same inlet metal angle.
Simulation results show that the new profile maintains the characteristic that the total static pressure and the static pressure are improved compared with the original profile, and the new profile has stronger high supercharging capacity under the condition of different height differences, which is consistent with the front load design. Therefore, the new profile more easily meets the pressure rise requirement during application.
The efficiency is left of the peak efficiency, whether it is a new or a new profile, indicating that the fan blade has better high flow characteristics. The new profile is relatively low in efficiency in the low flow section and higher in efficiency in the high flow section, which means that the new profile is more suitable for low-load application with smaller height difference and the negative attack angle characteristic is better, which is consistent with the general characteristic of the front loading profile. The smoothness and consistency of the power characteristics provide convenience for motor selection, and the motor is almost equal in power characteristics in the height difference debugging process.
Example 3
The impeller parameters of embodiment 3 of the present invention are:
the volume flow is 50000m 3/h;
pressure rise of 205Pa
The rotation speed is 750rpm;
the diameter is 1200mm;
blade chord length 231.5mm;
4, the number of blades;
Tip clearance 10mm;
atmospheric temperature 293.15K (i.e., 20 ℃);
atmospheric pressure 101325Pa.
The original blade profile and the new blade profile were also compared by numerical simulation, and fig. 12 to 15 are characteristic curves of full pressure, static pressure, efficiency and power as a function of flow rate, respectively. To be comparable, the same inlet metal angles are used for both, i.e. the original profile (height difference 110 mm) and the new profile (height difference 118.5 mm) in the figure have the same inlet metal angle. The simulation results also have the characteristics of example 2, i.e. the new profile maintains a higher total, static pressure lifting capacity over the full flow range (fig. 12, 13), and the new profile has a higher efficiency at high flow (fig. 14). For the design flow rate of 50000m 3/h, the full pressure realized by the original blade profile is 204.5Pa, and the new blade profile is 249Pa, which is far higher than the design requirement of 205 Pa. For the new blade profile, the pressure rise requirement of 205Pa is met under 56000m 3/h, which shows that the expected flow and pressure rise can be achieved even if the diameter of the fan is reduced to a certain extent, which clearly makes the fan more compact and effective, and is beneficial to reducing power and saving material cost.
The new profile height difference of example 3 was changed, and the full pressure and the efficiency as a function of flow rate obtained by numerical simulation were as shown in fig. 16 and 17 herein (in the figures, pt110 is the original profile, height difference 110mm, m is the new profile, and the height difference varies from 110mm to 130 mm). The results show that the new profile 130mm height difference (m 130) produced stall at a flow rate of less than 50000m 3/h, is the maximum height difference of the inventive profile in example 3, a usable solution from 118mm to 130mm, and the efficiency showed an increasing trend (fig. 17). The novel leaf profile has wide height difference adjustment range, which is closely related to the invention point of the leaf profile.
Meanwhile, the fan No. 12 of the embodiment 3 can be improved to the fan No. 11 through adjustment of the height difference, the flow and the pressure rise are kept unchanged, and the significant increase of the efficiency can further reduce the power requirement. These advantageous features are derived from the aerodynamic profile of the fan blade that the invention is required to protect.
By changing the loading mode, the blade profile of a certain type of low-speed low-load impeller is designed completely, the performance characteristics of the new and old fan blades are calculated and compared under two operation working conditions with different height differences, and the three-dimensional numerical simulation result shows that the fresh air blade has better application advantages.
The new blade profile is suitable for impellers with diameters above 1000mm, and the impellers with too small diameters can be reduced according to chord lengths, so that whether the application requirements are worth improving or not is needed, but the geometric integrity of the profile of the blade profile is not easy to change.
The above embodiments are only preferred examples of the present invention, and are not intended to limit the present invention, and any modifications, equivalent substitutions or modifications, such as tail edge cutting, thickness variation, geometric shape variation, fixing rod changing from circular shape to sheet shape, material replacement, etc. made within the design principle of the present invention are all considered as derivatives of the blade shape of the present invention, and are included in the scope of the present invention.
Claims (6)
1. The fan blade of the high-flow low-speed fan comprises a hub sleeve and fan blades, wherein a plurality of fan blades are uniformly arranged on the hub sleeve in a radial manner through a fixing structure, the hub sleeve is fixed on a fan rotating shaft, the number of the fan blades is 2-8, a fan blade shell is hollow, and a reinforcing rib is arranged in the middle of the fan blade shell;
The blade profile of each section is flat and straight, the blade profile geometry of each section is completely the same and can be divided into three areas, namely a front edge flow guiding area, a middle pressurizing area and a tail edge rectifying area, wherein the front edge flow guiding area occupies 10% of the chord length and can adapt to the relative airflow directions of incoming flows under different linear speeds, the middle pressurizing area is 50% of the chord length after the front edge flow guiding area, sufficient wind pressure rising is generated through the blade profile geometry difference and has a relative thickness of not less than 15%, so that a fixed rod can be installed in the blade profile, the tail edge rectifying area is 40% of the chord length at the rear part of the blade profile, and the tail edge rectifying area adopts a small wedge angle and a small curvature geometry to reduce static pressure difference and slow down exhaust loss;
The geometrical coordinates of the leaf surface of the three areas are generated by a plurality of polynomial functions, the mean camber line geometry adapting to the aerodynamic effect is firstly determined by the mean camber line oblique angle, a fourth polynomial fitting curve is generated according to the designed mean camber line oblique angle, the design formula is alpha= 30.782c 4-93.764c3+141.39c2 -131.79c+33.3706, wherein c is the percentage chord length, and alpha is the mean camber line oblique angle;
Secondly, calculating a mean camber line coordinate according to the mean camber line bevel angle to form a six-degree 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 percent chord length, y is the camber line relative deflection;
finally, generating geometrical coordinates of the blade profile surface by thickness distribution adapting to the front edge flow guiding, middle pressurizing and tail edge rectifying aerodynamic rules, wherein a thickness distribution design formula 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 high-flow low-speed fan as set forth in claim 1, wherein the fan blade shell is provided with a front end panel and a rear end panel at two ends, 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, and the front end panel is provided with a fixing rod through hole for accommodating the fixing rod to pass through.
3. The fan blade of the high-flow low-speed fan as set forth in claim 1, wherein the fan blade fixing structure comprises a plurality of U-shaped hoops and a fixing rod, and a plurality of annular grooves are formed in one side of the fixing rod, which is close to the hub sleeve, and the diameters of the annular grooves are matched with the U-shaped hoops.
4. The fan blade of the high-flow low-speed fan as claimed in claim 1, wherein the hub sleeve is provided with a semicircular groove, and the radius of the semicircular groove is matched with the fixed shaft of the fan blade.
5. The fan blade of the high-flow low-speed fan as claimed in claim 1, wherein the hub sleeve is further provided with a plurality of through holes, and the central rotating shaft hole is internally provided with a key slot.
6. The fan blade of the high-flow low-speed fan of claim 1, wherein the fan blade is made of aluminum alloy or glass fiber reinforced plastic.
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| CN112576546B (en) * | 2020-12-15 | 2021-12-03 | 华中科技大学 | Optimization method of non-uniform-thickness airfoil axial flow blade |
| CN119337529A (en) * | 2024-11-07 | 2025-01-21 | 大连斯频德环境设备有限公司 | A design method for aerodynamic blade profile of a high-performance straight-blade axial flow fan |
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| CN100595439C (en) * | 2006-08-24 | 2010-03-24 | 上海交通大学 | Axial-flow energy-saving fan blades formed by extrusion cutting process |
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Denomination of invention: A fan blade for a high flow rate low speed fan Granted publication date: 20250418 Pledgee: Zhejiang Shangyu Rural Commercial Bank Co.,Ltd. Yucheng Sub branch Pledgor: Zhejiang Zhefeng Technology Co.,Ltd. Registration number: Y2025980028530 |