CN113153812A - C-type starting forward-bent multi-wing centrifugal fan impeller and preparation method thereof - Google Patents

C-type starting forward-bent multi-wing centrifugal fan impeller and preparation method thereof Download PDF

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CN113153812A
CN113153812A CN202110352639.6A CN202110352639A CN113153812A CN 113153812 A CN113153812 A CN 113153812A CN 202110352639 A CN202110352639 A CN 202110352639A CN 113153812 A CN113153812 A CN 113153812A
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blade
impeller
centrifugal fan
type
curve
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CN113153812B (en
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刘小民
王加浩
田晨晔
席光
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Xian Jiaotong University
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Xian Jiaotong University
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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
    • F04D25/00—Pumping installations or systems
    • F04D25/02—Units comprising pumps and their driving means
    • F04D25/08—Units comprising pumps and their driving means the working fluid being air, e.g. for ventilation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
    • F04D17/08—Centrifugal pumps
    • F04D17/16—Centrifugal pumps for displacing without appreciable compression
    • 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
    • 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
    • F04D29/40—Casings; Connections of working fluid
    • F04D29/42—Casings; Connections of working fluid for radial or helico-centrifugal pumps
    • F04D29/44—Fluid-guiding means, e.g. diffusers
    • F04D29/441—Fluid-guiding means, e.g. diffusers 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
    • F04D29/66—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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction

Abstract

The invention discloses a C-type starting forward-bent multi-wing centrifugal fan impeller and a preparation method thereof, a fish body central line equation of a C-type starting curve section of cyprinid fish is obtained by adopting a reverse reconstruction mode to form an impeller structure comprising an impeller front disk, an impeller rear disk and a circumferential array between the impeller front disk and the impeller rear disk, the section of a blade vertical to the width direction of the blade is a C-type section, the middle arc line of the C-type section is fitted with a curve to form a blade structure, the impeller is used on the camber line of the blades of the multi-wing centrifugal fan, can improve the airflow flow in the impeller flow channel, reduce the flow separation of the airflow in the flow channel between the blades, inhibit the vortex, reduce the pressure pulsation and turbulent flow pulsation on the surfaces of the blades on the premise of increasing the air quantity of the fan, therefore, the air quantity and the air pressure of the fan are increased, the pneumatic noise of the fan is reduced, the resistance reduction effect can be effectively realized, and the effect of effectively reducing the pneumatic noise of the impeller while increasing the air and increasing the pressure is achieved.

Description

C-type starting forward-bent multi-wing centrifugal fan impeller and preparation method thereof
Technical Field
The invention belongs to a multi-wing centrifugal fan impeller, and particularly relates to a C-type starting forward-bent multi-wing centrifugal fan impeller and a preparation method thereof.
Background
The multi-wing centrifugal fan has the characteristics of compact structure, high pressure coefficient, large flow coefficient and the like, so the multi-wing centrifugal fan is widely applied to the field of household appliances such as air conditioners, range hoods and the like, and along with the vigorous promotion of energy conservation and emission reduction, the air conditioners, the range hoods and the like have higher and higher requirements on the air volume and the air pressure of the multi-wing centrifugal fan. The impeller is used as a main acting part of the multi-wing centrifugal fan, and the performance of the impeller determines the air volume, the air pressure and the noise of the fan. When the multi-wing centrifugal fan operates, the impeller is used as the most main working part of the multi-wing centrifugal fan, and when airflow flows through the blade channel of the impeller, large turbulence pulsation is generated on the wall surface of the blade, and large internal flow vortex is generated in the blade channel, so that airflow flowing in the blade channel is blocked, and aerodynamic noise is generated. Therefore, on the premise of increasing the air volume and the air pressure of the fan, the airflow flowing condition in the impeller flow channel is improved, the flow vortex in the inter-blade flow channel is reduced, and the turbulence pulsation of the inter-blade flow channel is reduced, which is the main task of the structural design of the multi-wing centrifugal fan impeller. The selection types of camber line curves of the existing multi-wing centrifugal fan are arc camber lines which are formed by single arcs or multiple arcs. The blade camber line formed by a single circular arc or multiple circular arcs is limited by the characteristics of the circular arcs and only has circular arc radius, circular arc central angle and arch point circular radius structures, so that the design freedom of the shape of the flow channel between the blades is low, reasonable streamline blade camber line molded lines cannot be formed, the flow channel between the blades is relatively unreasonable, a large number of vortex areas generated by flow separation exist between the blade flow channels, the flow loss is large, and the pneumatic performance is correspondingly reduced.
Disclosure of Invention
The invention aims to provide a C-type starting forward-bent multi-wing centrifugal fan impeller and a preparation method thereof, so as to overcome the defects of the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
the utility model provides a C type starts preceding curved formula multiple wing centrifugal fan impeller, includes impeller front bezel, impeller back plate and circumference array in the blade between impeller front bezel and impeller back plate, and the cross-section of blade perpendicular to its width direction is C type cross-section, and the mean camber line in C type cross-section is first curve y1jA second curve y2jAnd a third curve y3jFitting curves which are connected in sequence;
Figure BDA0003002619790000021
wherein the first curve y1jEnd of and third curve y3jThe connecting line of the end parts is the chord length of the blade, the included angle between the chord length of the blade and the tangent line of the inner ring of the fan impeller is 120-130 degrees, and j is 0.36-1.8 degrees.
Furthermore, the arc length of two adjacent blades between the front impeller disc and the rear impeller disc along the inner ring of the fan impeller is C, and C is-0.0015 (A)3+0.0617(A)2+0.4334A, where A is the length of the chord of the blade.
Further, the mean camber line fitting equation of the C-shaped cross section is:
Figure BDA0003002619790000022
k is the scaling size.
Further, the thickness of the blade is not more than 0.5 mm.
A C-type starting forward-bent multi-wing centrifugal fan impeller forming method comprises the following steps:
s1, obtaining a fish body center line equation of the C-type starting curve segment of the cyprinid fish in a reverse reconstruction mode;
s2, obtaining the length of the chord length of the blade according to the known inner ring diameter and outer ring diameter of the fan impeller and the known inlet angle beta of the camber line of the blade, comparing the length of the chord length of the blade with the chord length of a fish body centerline equation to obtain a scaling ratio, and then scaling the fish body centerline equation according to the scaling ratio to obtain a blade camber line fitting equation;
and S3, obtaining a mean camber line curve according to a mean camber line fitting equation of the blade, performing left-right equal-thickness deviation to obtain a C-shaped section, performing linear stretching on the C-shaped section to obtain a blade structure, and arranging the blades between a front impeller disc and a rear impeller disc along the circumference to obtain the multi-wing centrifugal fan impeller.
Further, specifically, a body profile of a C-type starting PIV flow field of the cyprinus carpio is obtained in a reverse reconstruction mode, the lowest point of the central profile of the cross section of the cyprinus carpio in the C-type starting form is used as the origin, the tangent line of the lowest point of the central profile is used as the Y axis to establish an x-Y coordinate system, characteristic points (x, Y) of the central line of the cyprinus carpio are extracted, and the central line of the cyprinus carpio is established to obtain a blade camber line fitting curve.
Further, the fish body centerline equation obtained in step s1 is:
Figure BDA0003002619790000031
j＝0.36-1.8。
further, the mean arc fitting equation is:
Figure BDA0003002619790000032
k is the scaling size.
Further, the blade pitch of two adjacent blades is C:
C＝-0.0015(A)3+0.0617(A)2+0.4334A，
where a is the length of the chord of the blade.
Furthermore, the included angle between the tangent of the camber line of the front edge of the blade and the tangent of the inner ring of the fan impeller is 10-20 degrees.
Compared with the prior art, the invention has the following beneficial technical effects:
the invention relates to a C-type starting forward-bent multi-wing centrifugal fan impeller, which adopts an impeller front disk, an impeller rear disk and blades circumferentially arrayed between the impeller front disk and the impeller rear disk, wherein the section of each blade, which is vertical to the width direction, is a C-type section, and a blade structure formed by fitting a curve to a mean camber line of the C-type section is used on the mean camber line of the blades of the multi-wing centrifugal fan.
Furthermore, the impeller adopting the carp C-shaped starting blade has better inter-blade flow channels, and meanwhile, the blades can inhibit flow separation in the blade channels, reduce vortexes in the blade channels and enhance the work capacity of the blades.
A C-type starting forward-bent multi-wing centrifugal fan impeller manufacturing method includes the steps that a camber line of blades is obtained according to body molded lines of a carp C-type starting PIV flow field, the shape of flow channels among the blades can be more reasonable due to the adoption of a C-type starting fish body midline structure, flow separation among the blade flow channels can be greatly reduced, the internal flow condition of the blade channels is improved, vortexes and turbulence pulsation in the blade channels are reduced, and flow loss is reduced, so that the pneumatic performance is correspondingly improved.
Drawings
Fig. 1 is a schematic view of a fan impeller blade mounting structure in an embodiment of the present invention.
Fig. 2 is a schematic perspective view of a fan impeller according to an embodiment of the present invention.
Fig. 3 is a schematic perspective view of a blade according to an embodiment of the present invention.
Fig. 4 is a schematic diagram of a fish body centerline structure obtained by using a reverse reconstruction method in the embodiment of the present invention.
FIG. 5 is a schematic structural diagram of a C-shaped starting fish body in the embodiment of the invention; FIG. 5a is a C-shaped starting fish body profile; fig. 5b is a comparison coincidence of the center line of the C-shaped starting fish body and the cross section of the blade.
FIG. 6 is a graph of a mean camber line fit in an embodiment of the present invention.
FIG. 7a is a graph of the results of a first curve fit curve; FIG. 7b is a graph of the results of a second curve fit curve;
FIG. 7c is a graph of the results of a third curve fit; FIG. 7d is a graph of the results of a fourth curve fit.
Fig. 8 is a schematic view of an impeller mounting structure in an embodiment of the present invention.
Fig. 9a is a velocity flow diagram of a multi-wing centrifugal fan applying a conventional circular arc blade at a main air inlet side along an axial 50% section, and fig. 9b is a velocity flow diagram of a multi-wing centrifugal fan applying a carp-like C-shaped starting blade at a main air inlet side along an axial 50% section.
FIG. 10a is a velocity flow diagram of a multi-blade centrifugal fan employing conventional circular-arc blades at 90% axial cross-section at the primary inlet side; fig. 10b is a velocity flow diagram of a multi-wing centrifugal fan employing a carp-like C-shaped start-up blade at a main air inlet side along an axial 90% cross-section.
FIG. 11a is a cloud of turbulent kinetic energy at 50% of the cross-section of a conventional curved-blade multi-blade centrifugal fan along the axial direction at the primary air inlet side; FIG. 11b is a cloud of turbulent kinetic energy at 50% of the axial cross-section of a multi-wing centrifugal fan using a carp-like C-shaped start-up blade at the primary air inlet side.
FIG. 12a is a cloud of turbulent kinetic energy at 90% of the axial cross-section of a multi-wing centrifugal fan employing conventional circular arc blades at the primary air inlet side; FIG. 12b is a cloud of turbulent kinetic energy at 90% of the axial cross-section of a multi-wing centrifugal fan using a carp-like C-shaped start-up blade at the primary air inlet side.
FIG. 13a is a velocity vector diagram of a multi-blade centrifugal fan employing conventional circular-arc blades at 90% of the cross-section of the main inlet side along the axial direction; fig. 13b is a velocity vector diagram of a 90% cross section of a multi-wing centrifugal fan using a carp-like C-shaped start blade along the axial direction at the side of a main air inlet.
Wherein, 1, impeller front disc; 2. an impeller rear disc; 3. a blade; 4. blade chord length; 5. a first curve; 6. a second curve; 7. a third curve; 8. the included angle between the chord length of the blade and the tangent line of the inner ring of the fan impeller; 9. the blade mean camber line inlet angle; 10. blade mean camber exit angle; 11. the diameter of the inner ring; 12. the diameter of the outer ring; 13. blade pitch; 14. the central line of the fish body; 15. the molded line at the fish head; 16. deflecting the contour of the inner side of the fish body; 17. deflecting the outer contour of the fish body; 18. a vertical line.
Detailed Description
The invention is described in further detail below with reference to the accompanying drawings:
as shown in fig. 1 and 2, a C-shaped starting forward-bent multi-wing centrifugal fan impeller comprises an impeller front disk 1, an impeller rear disk 2 and blades 3 circumferentially arrayed between the impeller front disk and the impeller rear disk, wherein a section of each blade 3 perpendicular to the width direction of the blade is a C-shaped section, and a mean camber line of the C-shaped section is a first curve y 1j5. Second curve y2j6 and a third curve y3j7 sequentially connected fitting curves, namely a fish body central line equation;
Figure BDA0003002619790000061
wherein the first curve y 1j5 ends with the trailing edge of the blade, the third curve y3jThe end part of the blade 7 is a blade front edge; the connecting line between the tail edge of the blade and the front edge of the blade is the chord length 4 of the blade, and the included angle (beta) 8 between the chord length 4 of the blade and the tangent line of the inner ring of the fan impeller is 120-130 degrees; i.e. the line between the front and rear ends of the blade 3 is the blade chord length.
The section of the blade 3 perpendicular to the width direction is a C-shaped section, namely the cross section of the blade is a C-shaped section, the mean camber line of the C-shaped section of the blade 3 is in the shape of a center line of a C-shaped starting fish body of the carp imitation, and the mean camber line is a streamline spline curve.
As shown in fig. 1, an included angle (β 1) between a tangent of a camber line of a leading edge of a blade 3 and a tangent of an inner ring of a fan impeller is a blade camber inlet angle 9, an included angle (β 2) between a tangent of a camber line of a trailing edge of the blade 3 and a tangent of the inner ring of the fan impeller is a blade camber outlet angle 10, wherein the range of the blade camber inlet angle β 1 is 10 to 20 °, the range of the blade camber outlet angle β 2 is 160 and 175 °, and since the shape of the camber line of the blade is fixed, only one of the parameters β 1 and β 2 needs to be determined, and the position of the camber line of the blade can be fixed. The cross sections of the blades are equal.
The blade distance between two adjacent blades 3 between the front impeller disk and the rear impeller disk is C, namely the two adjacent blades 3 between the front impeller disk and the rear impeller disk are alongThe arc length of the inner ring of the fan impeller is C, C is-0.0015 (A)3+0.0617(A)2+0.4334a, where a is the length of the chord length 4 of the blade, and the length of the chord length 4 of the blade can be obtained according to the known inner ring diameter (R1)11 and outer ring diameter (R2)12 of the fan impeller and the included angle (β)8 between the chord length 4 of the blade and the tangent line of the inner ring of the fan impeller. An included angle beta 3 between a chord line of the blade and a tangent line at the starting point of a camber line of the blade (the endpoint of the camber line of the front edge of the blade 3) is a fixed value, and beta 03 is 110 degrees; the included angle between the chord length 4 of the blade and the tangent line of the inner ring of the fan impeller is beta, and beta is beta 1+ beta 3, so that the chord line installation angle beta of the blade can be determined after the beta 1 is determined, the included angle beta between the chord length 4 of the blade and the tangent line of the inner ring of the fan impeller is determined, the included angle beta is deviated from the arc tangent line of the starting point of the chord line of the blade on the inner ring of the fan impeller by the angle beta, and then the included angle beta is extended to the outer diameter circle of the fan impeller, so that the length A of the chord length of the blade can be determined. After the arc length (namely the blade distance 13) of two adjacent blades 3 along the inner ring of the fan impeller is determined by the formula, the number of the blades of the impeller can be obtained, and the C-shaped starting forward-bent multi-blade centrifugal fan impeller imitating the carp family can be obtained.
As shown in figure 3, the camber line of the blade 3 is matched with the central line of a C-shaped starting fish body when carp swims, the carp has efficient and quick swimming performance due to C-shaped starting, no vortex exists around the whole fish body profile and the fish body resistance is small when the C-shaped starting is carried out, and the central line of the fish body is in a good streamline form and has very effective resistance reduction characteristics. As shown in fig. 4, by adopting a reverse reconstruction mode, firstly, a body profile and a flow field diagram of a carp C-type starting PIV flow field are obtained, and a low-resistance and streamline fish body center line when the carp C-type is started is obtained.
The method comprises the following steps of obtaining a C-type started camber line structure of the cyprinid fish in a reverse reconstruction mode, and adopting the following method:
firstly, carrying out PIV experiment on the C-type starting posture of the cyprinoid to obtain the C-type starting posture of the cyprinoidThe fish shape and flow field of the fish are shown in fig. 4; then, an x-Y coordinate system is established by taking the lowest point of the center profile of the fish body cross section of the carp in the C-type starting form as the origin and taking the tangent line of the lowest point of the center profile as the Y axis, as shown in fig. 5a, and characteristic points (x1, Y1) of the external shape of the fish body cross section profile are extracted, so as to establish the external shape of the fish body of the carp in the C-type starting form, and characteristic points (x, Y) of the central line of the fish body are extracted according to the external shape of the fish body drawn when the fish body is in the C-type starting form, so as to establish the central line 14 of the fish body, as shown in fig. 5 a. Segmenting the extracted fish body central line according to the curve characteristics of the fish body central line to obtain a first curve characteristic point, a second curve characteristic point, a third curve characteristic point and a fourth curve characteristic point, as shown in fig. 6; respectively fitting according to the characteristic points (x, y) of the four molded lines to obtain a first curve, a second curve, a third curve and a fourth curve, and respectively constructing y of the central curve of each fish body1j、y2j、y3jAnd y4jAs shown in fig. 7a, 7b, 7c, 7 d. As shown in fig. 4, the fourth curve is the molded line 15 at the fish head, and since the fish head is not provided with a skull, but not a spinal bone, and cannot be bent, the center line at the fish head is a straight line, as shown in fig. 4 and 5a, the center line at the fish head, i.e., the fourth curve, is not applied to the middle arc line of the blade, and only the first curve, the second curve and the third curve are applied to the middle arc line of the blade. And three fitting curves obtained according to the first curve, the second curve and the third curve are sequentially connected end to end, and the shape of the fitting curves is the shape of the arc line in the blade.
According to the constructed C-type carp starting fish body centerline equation, when the C-type carp starting fish body centerline equation is applied to a blade mean camber line, firstly, the length A of the chord length of the blade is determined according to the known inner ring diameter 11 and outer ring diameter 12 of a fan impeller and the known inlet angle beta 1 or outlet angle beta 2 of the blade mean camber line, the scaling ratio K is obtained by comparing the length A of the chord length of the blade with the chord length B of the mean camber line (namely the chord length of the fish body centerline equation curve), and then the whole mean camber line equation is scaled according to the multiple relation of K to obtain the intermediate equation yk of the C-type carp starting blade which is applied to determining the known inner ring diameter 11 and outer ring camber line diameter 12 and the known inlet angle beta 1 or outlet angle beta 2 of the blade mean camber line. Discretizing the obtained blade mean camber line equation yk to obtain a series of characteristic points (x, yk) of the blade mean camber line of the carp C-shaped starting blade simulation blade, then drawing the blade mean camber line according to the series of characteristic points (x, yk), performing left-right equal-thickness offset on the arranged blade mean camber line to obtain a C-shaped section of the carp C-shaped starting blade simulation, performing linear stretching on the C-shaped section to obtain the carp C-shaped starting forward-bent multi-wing centrifugal fan blade 3, and finally forming the corresponding relation between the carp C-shaped starting forward-bent blade simulation and the fish body center line as shown in fig. 5 b.
According to the constructed carp-imitated C-shaped starting forward-bent multi-wing centrifugal fan blade, the camber line of the blade is only required to determine the inlet angle 9 of the camber line of the blade or the outlet angle 10 of the camber line of the blade except for the inner ring diameter (R1)11 and the outer ring diameter (R2)12 of the impeller, and the blade is different from parameters such as the radius of a circular arc, the central angle, the radius of a camber point circle and the like of the blade with the camber line of a single-circular-arc blade or a multi-circular-arc blade. Therefore, for the two parameters of the blade of the invention, only one of the parameters of the blade is needed to be determined, and the position of the camber line of the blade can be fixed, namely, only one of the parameters of the inlet angle 9 of the camber line of the blade or the outlet angle 10 of the camber line of the blade is needed to be determined, and the other parameter is automatically determined.
Establishing an x-Y coordinate system by taking the lowest point of the center profile of the cross section of the carp body in the C-type starting form of the carp as an origin and taking a tangent line at the lowest point of the center profile as a Y axis, extracting characteristic points (x1, Y1) of the profile of the cross section profile of the fish body, establishing the profile of the fish body of the carp in the C-type starting form of the carp, making a plurality of vertical lines 18 from the characteristic point of the deflected inner profile 16 of the fish body to the deflected outer profile 17 of the fish body, taking the middle points (x, Y) of all vertical lines of the fish body in the form, namely the characteristic points (x, Y) of the center line of the fish body, and sequentially connecting the extracted characteristic points (x, Y) of the center line of the fish body to establish the center line 14 of the carp in the C-type starting form of the carp, as shown in fig. 4 and 5.
Figure BDA0003002619790000091
The above equation is a fish body midline equation under the C-type starting state of fish bodies with different sizes, wherein j represents the difference degree of the fish body midline sizes when the C-type starting of the cyprinus carpio with different sizes is carried out, and j is 0.36-1.8.
According to the known inner ring diameter (R1)11 and outer ring diameter (R2)12 and the included angle (beta) 8 between the chord length 4 of the blade and the tangent line of the inner ring of the fan impeller, the length of the chord length 4 of the blade can be obtained, and the equations of the first curve, the second curve and the third curve are scaled to obtain the camber line equation of the blade applied to a specific impeller, namely the scaled camber line equation, which is shown as follows:
Figure BDA0003002619790000101
wherein s1, s2, s3 are the equation y of fitting the curve 1 according to the specific blade size1jFitting curve 2 equation y2jFit curve 3 equation y3jScaled blade camber line equation scaled, K being the scale at which the scaling is performed.
The three-dimensional Reynolds average Navier-Stokes equation set was numerically solved using the computational fluid dynamics commercial software FLUENT. The Mach number of the flow in the fan is small, the flow can be regarded as incompressible flow, and the turbulence model is a standard k-e model. Comparing and analyzing the internal flow state and air volume of the multi-wing centrifugal fan adopting the cyprinid-like C-type starting forward-bent multi-wing centrifugal fan blade and the multi-wing centrifugal fan adopting the conventional single-arc blade, wherein the number of the blades is 60, the inner diameter of the impeller is 210mm, and the outer diameter of the impeller is 250 mm; the inlet angle of the blade adopting the blade structure is 20 degrees; as shown in fig. 9. The numerical calculation model is shown in fig. 8. Calculating the maximum air quantity when the static pressure at the outlet is 0, wherein the air quantity of the multi-wing centrifugal fan adopting the Cyprinus carpiod C-shaped starting forward-bent type multi-wing centrifugal fan blade is 1332m3The corresponding efficiency is 37.3 percent, and the air quantity of the multi-wing centrifugal fan adopting the conventional circular arc blade impeller is 1240m3Compared with the traditional Chinese medicine, the air quantity of the Cyprinus carpiovar C-shaped starting forward-bent type multi-wing centrifugal fan blade fan is increased by 92m3The air volume is relatively increased by 7.5 percent。
The C-shaped section of the carp-like C-shaped starting forward-bent multi-wing centrifugal fan blade has a larger bending degree compared with a single-arc or double-arc blade. The area of the pressure surface of the C-shaped starting forward-bent type multi-wing centrifugal fan blade imitating the carp family is 4235mm2The area of the pressure surface of the conventional single-arc blade is 3024mm2The area of the pressure surface of the straight blade is increased by 1611mm relative to the area of the pressure surface of the conventional straight blade2And the improvement is 40 percent. The area of the pressure surface of the C-shaped starting forward-bent blade of the carpool-imitating family fish is greatly increased, so that the C-shaped starting forward-bent blade has stronger acting capacity than that of a single-arc blade and a multi-arc straight blade, and the flow of a fan is relatively increased by about 7.5%.
Based on the numerical calculation, the flow field in the fan is analyzed by cutting off 50% and 90% of the cross section of the main air inlet side of the impeller along the axial direction, as shown in fig. 9-12. Fig. 9 is a velocity flow diagram of a multi-blade centrifugal fan using a conventional arc blade and a carp-like C-shaped starting forward-bent blade at a main air inlet side along an axial 50% section, and a comparison of the velocity flow diagram and the velocity flow diagram shows that the swirl in the impeller flow channel of the blade of the present invention at the main air inlet side of the impeller along the axial 50% section is significantly reduced to a great extent, the swirl in each inter-blade flow channel almost disappears, the flow in the blade channel is more stable, and the flow velocity is relatively higher. Fig. 10 is a velocity flow diagram of a multi-blade centrifugal fan using a conventional arc blade and a carp-like C-shaped starting forward-bent blade at a main air inlet side along an axial 90% cross section, and a comparison of the velocity flow diagram and the velocity flow diagram shows that the intercalary flow channel vortex of the carp-like C-shaped starting blade is greatly reduced in the left area of the impeller, and compared with the conventional arc blade, the intercalary flow channel vortex is almost disappeared in the lower area of the impeller, the flow in the blade channel is more stable, and the flow velocity is relatively high. Therefore, the impeller adopting the carp-like C-shaped starting blade has a better flow passage between blades, and meanwhile, the blade can inhibit flow separation in the flow passage, reduce the vortex in the flow passage and enhance the work capacity of the blade. Fig. 11 is a turbulent kinetic energy cloud chart of a multi-wing centrifugal fan applying a conventional arc blade and a carp-like C-shaped starting forward-bent blade at a main air inlet side along an axial 50% section, and a comparison of the two shows that on the 50% section of the impeller main air inlet side, the intensity of turbulent flow in the fan adopting the carp-like C-shaped starting forward-bent blade is obviously smaller than that of the conventional arc blade fan, the intensity of turbulent kinetic energy in a fan outlet area, a volute tongue area and an impeller left side area is obviously weakened, and the intensity of turbulent flow in other impeller areas is weakened to different degrees relative to the arc blade fan. Fig. 12 is a turbulent kinetic energy cloud chart of a multi-wing centrifugal fan applying a conventional arc blade and a carp-like C-shaped starting forward-bent blade, wherein the cross section of the multi-wing centrifugal fan is 90% of that of the multi-wing centrifugal fan at the main air inlet side along the axial direction, and a comparison between the two shows that the turbulence intensity in the fan adopting the carp-like C-shaped starting forward-bent blade is obviously smaller than that of the conventional arc blade fan, the turbulence kinetic energy intensity of the left area of the whole impeller is obviously weakened, and the turbulence intensity of other impeller areas is weakened to different degrees compared with the arc blade fan. Fig. 13 is a velocity vector diagram of a multi-wing centrifugal fan applying a conventional arc blade and a carp-like C-type starting blade, which is a 90% cross section along the axial direction at the side of a main air inlet, and a comparison of the two shows that the swirl in the inter-leaf flow channel of the blade is reduced, the flow separation in the leaf channel is weakened, the velocity vector at the outlet of the blade is more uniform, and the outlet velocity is higher, which indicates that the working capacity of the blade is relatively higher, the area change of the leaf channel is more consistent with the fluid flow characteristic, and meanwhile, the inlet angle of the airflow at the inlet of the blade is tangent to the inlet angle of the arc line in the carp-like C-type starting blade, the inlet has no impact, and the airflow flow characteristic at the inlet is better improved. This further demonstrates that the carp-like C-shaped starting blade has better hydrodynamic properties than the circular arc blade.
The cloud pictures and the flow charts in the fan adopting the arc blades and the C-shaped starting forward-bent blades imitating the carpoolfish show that the vortices in the blade channels adopting the C-shaped starting forward-bent blades imitating the carpoolfish are obviously reduced, the development of a large turbulent flow area in the blade channels is inhibited, and the flow separation of airflow in the blade channels is also relieved, so that the aerodynamic noise of the blade channels caused by the pressure pulsation on the surfaces of the blades is reduced.
The intensity and the size of the vortex in the C-shaped starting forward-bent blade channel of the carp-like fish are reduced compared with those of an arc blade, flow separation is relieved, pressure pulsation and turbulence pulsation of a suction surface of the blade and a front edge of the blade are weakened, and airflow speed at an outlet of the blade is higher and more uniform, so that the purposes of increasing flow and wind pressure of a fan and reducing aerodynamic noise of the blade channel are achieved.

Claims (10)

1. The utility model provides a C type starts preceding curved formula multiple wing centrifugal fan impeller, its characterized in that, including impeller front bezel (1), impeller back plate (2) and circumference array in impeller front bezel and impeller back plate between blade (3), blade (3) be C type cross-section perpendicular to its width direction's cross-section, the pitch arc of C type cross-section is first curve y1j(5) A second curve y2j(6) And a third curve y3j(7) Fitting curves which are connected in sequence;
Figure FDA0003002619780000011
wherein the first curve y1j(5) End of and third curve y3j(7) The connecting line of the end parts of the blades is a blade chord length (4), the included angle (8) between the blade chord length (4) and the tangent line of the inner ring of the fan impeller is 120-130 degrees, and j is 0.36-1.8.
2. The impeller of the centrifugal fan with multiple blades and forward bending starting type in C type as claimed in claim 1, wherein the arc length of two adjacent blades (3) between the front disk of the impeller and the back disk of the impeller along the inner ring of the impeller of the fan is C, C-0.0015 (A)3+0.0617(A)2+0.4334A, where A is the length of the chord (4) of the blade.
3. The C-shaped startup forward-curved type multi-wing centrifugal fan impeller according to claim 1, wherein the mean camber line fitting equation of the C-shaped section is as follows:
Figure FDA0003002619780000012
k is the scaling size.
4. A C-type startup forward-curved multi-wing centrifugal fan impeller according to claim 1, characterized in that the thickness of the blades (3) is not more than 0.5 mm.
5. A preparation method of a C-type starting forward-bent multi-wing centrifugal fan impeller is characterized by comprising the following steps:
s1, obtaining a fish body center line equation of the C-type starting curve segment of the cyprinid fish in a reverse reconstruction mode;
s2, obtaining the length of the chord length of the blade according to the known inner ring diameter and outer ring diameter of the fan impeller and the known inlet angle beta of the camber line of the blade, comparing the length of the chord length of the blade with the chord length of a fish body centerline equation to obtain a scaling ratio, and then scaling the fish body centerline equation according to the scaling ratio to obtain a blade camber line fitting equation;
and S3, obtaining a mean camber line curve according to a mean camber line fitting equation of the blade, performing left-right equal-thickness deviation to obtain a C-shaped section, performing linear stretching on the C-shaped section to obtain a blade structure, and arranging the blades between a front impeller disc and a rear impeller disc along the circumference to obtain the multi-wing centrifugal fan impeller.
6. The preparation method of the C-type startup forward-bent multi-wing centrifugal fan impeller according to claim 5, characterized by specifically obtaining a body profile of a carp C-type startup PIV flow field by a reverse reconstruction method, establishing an x-Y coordinate system by taking a lowest point of a center profile of a fish body cross section of a carp in a C-type startup form as an origin and a lowest point tangent line of the center profile as a Y axis, extracting feature points (x, Y) of a fish body center line, and establishing the fish body center line by the x-Y coordinate system to obtain a blade middle arc line fitting curve.
7. The method for preparing the C-shaped starting forward-bent multi-wing centrifugal fan impeller according to claim 5, wherein the fish body centerline equation obtained in step s1 is as follows:
Figure FDA0003002619780000021
j＝0.36-1.8。
8. the method for preparing the C-shaped starting forward-bent type multi-wing centrifugal fan impeller according to claim 7, wherein the mean camber line fitting equation is as follows:
Figure FDA0003002619780000022
k is the scaling size.
9. The method for preparing the C-shaped starting forward-bent type multi-wing centrifugal fan impeller according to claim 5, wherein the blade spacing between two adjacent blades is C:
C＝-0.0015(A)3+0.0617(A)2+0.4334A，
where a is the length of the chord of the blade.
10. The method for preparing a C-shaped starting forward-bent multi-wing centrifugal fan impeller according to claim 5, wherein an included angle between a camber line tangent of a blade leading edge of each blade and a fan impeller inner ring tangent is 10-20 °.
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