CN113007135A - Axial flow blade and axial flow fan - Google Patents

Axial flow blade and axial flow fan Download PDF

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Publication number
CN113007135A
CN113007135A CN202110447622.9A CN202110447622A CN113007135A CN 113007135 A CN113007135 A CN 113007135A CN 202110447622 A CN202110447622 A CN 202110447622A CN 113007135 A CN113007135 A CN 113007135A
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China
Prior art keywords
blade
line
fan
section
axial flow
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CN202110447622.9A
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CN113007135B (en
Inventor
王军
丁炎炎
梁钟
蒋博彦
杨筱沛
肖千豪
凌杰达
詹婷军
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Huazhong University of Science and Technology
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Huazhong University of Science and Technology
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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
    • F04D19/00—Axial-flow pumps
    • F04D19/002—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
    • 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
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D29/00—Details, component parts, or accessories
    • F04D29/66—Combating cavitation, whirls, noise, vibration or the like; Balancing
    • F04D29/661—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps
    • F04D29/667—Combating cavitation, whirls, noise, vibration or the like; Balancing especially adapted for elastic fluid pumps by influencing the flow pattern, e.g. suppression of turbulence

Abstract

The invention belongs to the field of axial flow fans, and discloses an axial flow blade, wherein the profile of the axial flow blade comprises a blade leading edge line (1), a blade pressure surface profile (2), a blade suction surface profile (3) and a blade trailing edge line (4), wherein the blade pressure surface profile (2) and the blade suction surface profile (3) are formed by stacking according to a preset airfoil profile thickness rule by taking a middle arc (5) as a reference; the camber line arc (5) changes from the root of the blade to the top of the blade along the radial position of the fan according to a specific bending rule; the change curve of the blade placing angle of the camber line arc on the blade section along with the blade section relative to the blade height and the change curve of the blade bending angle along with the blade section relative to the blade height are all constructed by a quadratic B-spline (B-spline) curve. The invention controls the blade setting angle and the blade bending angle to be distributed along the radial direction of the blade through the secondary B-Spline curve controlled by specific parameters, and aims to effectively improve the efficiency of the fan.

Description

Axial flow blade and axial flow fan
Technical Field
The invention belongs to the field of axial flow fans, and particularly relates to an axial flow blade and an axial flow fan.
Background
Novel distortion axial compressor fan blade is as a general impeller machinery, and the wide application is in various ventilation and pneumatic heat dissipation occasions, and its operating characteristic includes: the airflow flows into the impeller flow channel, the impeller enables the airflow to obtain energy, and a blade top gap exists between the top of the movable blade of the axial flow fan and the casing, so that friction collision between the movable and static parts is avoided. Under the pressure differential between the suction and pressure surfaces at the blade tip, a portion of the fluid flows across the tip clearance to form a tip clearance flow, which typically occurs in the tip region in the form of a leakage vortex under the resultant action of the main flow velocity. The performance degradation that it causes is a major part of the mechanical and aerodynamic problems of the impeller. After the tip leakage flow and the main flow are mixed with each other, flow loss is caused, and the efficiency of the compressor is reduced. Meanwhile, the leakage flow can also cause airflow blockage in the compressor, so that the pressure ratio is reduced, even rotating stall is caused, and surging occurs. The flow separation and stall caused by the influence of the twisted incoming flow near the end wall and the transverse secondary flow in the blade cascade are one of the main factors influencing the stable operation of the fan and reducing the working efficiency of the fan.
For the traditional axial flow fan blade, the blade design usually follows the equal-annular-quantity twisting rule or the equal-reaction-force twisting rule, the impeller designed by the equal-annular-quantity twisting rule generally has higher efficiency, meanwhile, the theoretical pressure and the efficiency are better matched with the actual value, the blade reaction is usually larger, particularly, the blade root is easy to generate negative reaction, and the blade is seriously twisted. The impeller designed by the equal-reaction-degree twisting rule is low in reaction degree and small in blade twisting, but is low in general efficiency, and the designed performance parameters are more different from the actual performance parameters.
Disclosure of Invention
In view of the above defects or improvement requirements of the prior art, an object of the present invention is to provide an axial flow blade and an axial flow fan, based on a specific bending rule, a secondary B-Spline curve (i.e., a secondary B-Spline curve) controlled by specific parameters controls a blade placement angle and a blade bending angle to be distributed along a radial direction of the blade, so as to affect a load of the axial flow fan along the radial direction of the blade, improve a tip leakage vortex near a suction surface caused by a tip leakage flow, reduce a range of a transverse secondary flow in a cascade, reduce a flow separation loss at an impeller end region, and improve fan efficiency.
In order to achieve the above object, according to one aspect of the present invention, there is provided an axial flow vane, characterized in that the profile thereof is composed of a vane leading edge line (1), a vane pressure surface profile (2), a vane suction surface profile (3) and a vane trailing edge line (4), wherein the vane leading edge line (1) and the vane trailing edge line (4) are both arc-shaped for smoothly connecting the vane pressure surface profile (2) and the vane suction surface profile (3);
recording a connecting line of a front edge point P1 and a tail edge point P2 of the mean camber line arc (5) as a blade chord line, wherein the lengths of the blade chord lines corresponding to the mean camber line arcs (5) at different radial positions of the fan are the same preset fixed values along the radial direction of the fan from the root part to the top end of the blade; the blade pressure surface molded line (2) and the blade suction surface molded line (3) are obtained by stacking according to a preset airfoil thickness rule by taking a corresponding camber arc (5) as a reference;
and, camber line circular arc (5) of the different radial positions of fan are according to specific turn rule along the fan radial, by the blade root to the blade top change, corresponding blade pressure face molded lines (2) and blade suction surface molded lines (3) along fan radial stack can obtain blade pressure face and blade suction surface, specific:
recording the included angle between the chord line of the blade and the hub line of the fan as a blade placing angle beta, recording the blade at a certain radial position from the root part of the blade to the top end of the blade along the radial direction of the fanThe diameter corresponding to the section of the blade is Di, the relative blade height of the section of the blade is (Di-D2)/(D1-D2), the blade chord line on the section of the blade has a blade setting angle beta i, wherein D1 is the diameter corresponding to the section where the top end of the blade is located, and D2 is the diameter corresponding to the section where the root of the blade is located; and the blade chord line on the section where the blade top end is located has a blade mounting angle beta 1, the blade chord line on the section where the blade root is located has a blade mounting angle beta 2, then beta 2/beta 1 is more than or equal to 0.44 and less than or equal to 1.63, and the change curve of the ratio beta i/beta 1 along with the ratio (Di-D2)/(D1-D2) is a quadratic B-spline curve; the secondary B-spline curve is controlled by 3 control points, except 2 end point control points, the third control point is recorded as P4, and then the P4 point simultaneously satisfies the following conditions: di is more than or equal to 0.6P4D2)/(D1-D2) is not more than 0.9, and the distance between two connecting points of the change curve is recorded as L2, and the distance between P4 and the connecting line between the two connecting points of the change curve is recorded as L1, so that the L1/L2 is not less than 0.19 and not more than 0.31;
recording a central angle corresponding to the camber line arc (5) as a blade bending angle theta, recording a diameter corresponding to the blade section at a certain radial position from the blade root to the blade top end along the radial direction of the fan as Di, wherein the relative blade height of the blade section is (Di-D2)/(D1-D2), the blade bending angle of the camber line arc (5) on the blade section is thetai, wherein D1 is the diameter corresponding to the section where the blade top end is located, and D2 is the diameter corresponding to the section where the blade root is located; recording the blade bending angle of the mean camber line arc (5) on the section where the blade top end is located as theta 1, and the blade bending angle of the mean camber line arc (5) on the section where the blade root is located as theta 2, wherein theta 2/theta 1 is more than or equal to 1.56 and less than or equal to 2.33, and the variation curve of the ratio theta i/theta 1 along with the ratio (Di-D2)/(D1-D2) is a quadratic B-spline curve; the secondary B-spline curve is controlled by 3 control points, except 2 end point control points, the third control point is recorded as P7, and then the P7 point simultaneously satisfies the following conditions: di is more than or equal to 0.6P7D2)/(D1-D2) is not more than 0.9, and the distance between the connecting line of the two end points of the change curve is L4, and the distance between P7 and the connecting line of the two end points of the change curve is L3, so that the L3/L4 is not less than 0.125 and not more than 0.23.
As a further optimization of the invention, a quadratic B-Spline curve corresponding to the change curve of the ratio beta i/beta 1 along with the ratio (Di-D2)/(D1-D2) is obtained by firstly determining a P4 control point and then fitting by an interpolation method;
and a quadratic B-Spline curve corresponding to the change curve of the ratio theta i/theta 1 along with the ratio (Di-D2)/(D1-D2) is obtained by firstly determining a P7 control point and then fitting by an interpolation method.
Further preferably, the ratio of D2/D1 is 0.46. ltoreq.D 2/D1. ltoreq.0.52.
As a further optimization of the invention, if the lengths of the chord lines of the blades corresponding to the camber line arcs (5) at different radial positions of the fan are all C, C/D2 is more than or equal to 0.197 and less than or equal to 0.266.
In a further preferred embodiment of the present invention, the axial flow blade is provided on an annular impeller having an outer diameter D2.
According to another aspect of the present invention, the present invention provides an axial-flow impeller having the above axial-flow blades, characterized by comprising an annular impeller and a plurality of axial-flow blades uniformly arranged on the annular impeller, wherein the profile shapes of any 2 axial-flow blades are identical.
According to still another aspect of the present invention, there is provided an axial flow fan having the above axial flow impeller.
Compared with the prior art, the technical scheme of the invention controls the blade installation angle and the blade bending angle to be distributed along the radial direction of the blade through the secondary B-Spline curve, thereby influencing the load of the axial flow fan along the radial direction of the blade and reducing the flow loss caused by the leakage vortex at the blade top. The fan model adopting the design method of the invention is used for carrying out aerodynamic performance test on the basis of GB/T1236-2000 'Industrial ventilator-standardized air duct performance test', and the fan efficiency is improved to a certain extent.
The axial flow blade is designed based on a specific bending rule, and the axial flow blade and the axial flow fan based on the novel bending rule are obtained. In the axial flow blade, the twisting rule of the middle part of the blade is realized by distributing different blade placement angles at different radial positions, and the distribution rule adopts secondary B-spline curve fitting to obtain the radial distribution of the blade placement angles along the blade (the invention also controls the twisting degree of the middle part of the blade through P4); the bending rule of the middle part of the blade is realized by distributing different blade bending angles at different radial positions, and the distribution rule adopts quadratic B-spline curve fitting to obtain the radial distribution of the blade bending angles along the blade (the invention also controls the bending degree of the middle part of the blade by P7). The axial flow fan blade is formed by stacking blade profiles distributed at different radial positions (namely, the three-dimensional shape of the blade is formed by stacking different cross-section profiles of the impeller in the radial direction). The included angle between the chord line at the top of the blade and the axial direction is beta 1, the included angle between the chord line at the root of the blade and the axial direction is beta 2, and beta 2/beta 1 is more than or equal to 0.44 and less than or equal to 1.63. The blade twist rule is fitted by a B-spline curve. The camber line of the blade is in a single-arc structure, the central angle theta 2 of the camber line at the root position of the blade, and the central angle theta 1 of the camber line at the top position of the blade are respectively equal to or greater than 1.56 and equal to or less than 2.33 of theta 2/theta 1. And fitting the radial distribution rule of the central angle of the blade profile line through a B spline curve.
It is known in the prior art that a quadratic B-spline curve can be controlled in shape by three control points, for example, a complete B-spline curve expression can be obtained by a B-spline basis function according to a de Boor-Cox recursion formula (see, for example, the related literature: [1 ]]Hole computer graphics basic course [ M ]]Qinghua university Press, 2008 [2 ]]Boehm W.Inserting New Knots into B-spline Curves[J]Computer-Aided Design,1980,12(4): 199-. Except 2 end point control points, a third control point controls the bending degree of the middle part of the curve; in the invention, taking a quadratic B-spline curve corresponding to a change curve of the ratio beta i/beta 1 along with the ratio (Di-D2)/(D1-D2) as an example, control points of the quadratic B-spline curve are P3, P4 and P5 (wherein P3 and P5 are two-end point control points), the blade placing angle change at the radial position of a fan at the P4 point is smoother, and the distances L1/L2 between the P4 point and the connecting lines of the P3 and P5 points are larger, so that the overall twisting degree of the blade is higher (because the P4 meets the condition that 0.6 is more or less (Di is larger)P4D2)/(D1-D2) is less than or equal to 0.9, that is, the position where the blade placement angle changes most rapidly is located near the blade root). The change of the bending angle of the blade is the same.
According to the invention, the secondary B-Spline is adopted to construct the blade twisting rule, so that the radial load distribution of the blade is controlled, the flow field at the end region is influenced by the blade placing angle and the bending angle, the leakage flow at the top end of the blade is reduced, the leakage vortex of the blade top near the suction surface is inhibited, the range of the transverse secondary flow in the nearby blade channel is reduced, the flow loss caused by the flow separation at the top end of the blade is reduced, and the efficiency of the fan is improved.
Drawings
FIG. 1 is a schematic view of a profile of an axial flow fan impeller blade.
Fig. 2 is a schematic view of the profile of an axial flow fan impeller and blades of different radial cross sections according to the present invention. Line a shown in fig. 2 represents the fan leading edge hub line and line B represents the fan trailing edge hub line (leading edge hub line is parallel to trailing edge hub line).
FIG. 3 is a schematic diagram of a second B-spline curve for constructing a radial twisting rule and a blade profile bending rule of an axial flow fan.
FIG. 4 is a schematic view of a cross-sectional profile of a blade, an impeller and a three-dimensional shape of the blade of an axial flow fan in the prior art. Wherein (a) in fig. 4 corresponds to the sectional profile of the blade, (b) in fig. 4 corresponds to the three-dimensional shape of the blade, and (c) in fig. 4 corresponds to the three-dimensional shape of the impeller.
FIG. 5 is a schematic cross-sectional profile of an axial flow fan blade, an impeller and a blade in three-dimensional modeling according to an embodiment. Wherein (a) in fig. 5 corresponds to the blade section profile, (b) in fig. 5 corresponds to the three-dimensional shape of the blade, and (c) in fig. 5 corresponds to the three-dimensional shape of the impeller.
FIG. 6 is a schematic diagram of a cross-sectional profile of a blade, an impeller and a three-dimensional shape of the blade of the two-axis flow fan according to the embodiment. Wherein (a) in fig. 6 corresponds to the blade section profile, (b) in fig. 6 corresponds to the three-dimensional shape of the blade, and (c) in fig. 6 corresponds to the three-dimensional shape of the impeller.
FIG. 7 is a comparison diagram of the radial twist rule of the blades of the axial flow fan in different schemes.
FIG. 8 is a schematic diagram showing the comparison of the blade profile bending rules of different radial positions of blades of an axial flow fan in different schemes.
FIG. 9 is a comparison diagram of full pressure-flow coefficient curves of different axial flow fans.
FIG. 10 is a comparison diagram of efficiency-flow coefficient curves of different schemes of axial flow fans.
Fig. 11 is a schematic axial position and circumferential position of a middle section 1 of a flow passage of an axial flow fan. In fig. 11, (a) corresponds to an axial position diagram, and in fig. 11, (b) corresponds to a circumferential position diagram.
Fig. 12 is a schematic view of a streamline at a section 1 of a blade of a prior art axial flow fan (the position of the section 1 is shown in fig. 11).
FIG. 13 is a schematic view of the streamline at the section 1 of an axial flow fan blade according to the embodiment (the position of the section 1 is shown in FIG. 11).
FIG. 14 is a schematic view of a streamline at a section 1 of a blade of a biaxial fan according to the embodiment (the position of the section 1 is shown in FIG. 11).
The meaning of the reference symbols in fig. 1 is as follows: the blade is characterized in that 1 is a blade leading edge line, 2 is a blade pressure surface molded line, 3 is a blade suction surface molded line, 4 is a blade trailing edge line, and 5 is a camber line circular arc.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The novel twisted axial flow fan blade is characterized in that a blade profile is composed of a blade leading edge line 1, a blade pressure surface profile line 2, a blade suction surface profile line 3 and a blade trailing edge line 4, wherein the blade pressure surface profile line 2 and the blade suction surface profile line 3 are obtained by stacking according to a preset airfoil profile requirement by taking a mean camber line arc 5 as a reference (in the subsequent embodiment of the invention, the blade profile line is designed by adopting an NACA 65 airfoil profile for the axial flow fan blade, and other airfoil profiles known in the prior art can be adopted besides the NACA 65 airfoil profile. The blade leading edge line 1 and the blade trailing edge line 4 are in a circular arc structure and are smoothly connected with the pressure surface molded line 2 and the suction surface molded line 3. The blade profile configuration is shown in figure 1.
In addition, the mean camber line of the blade is in a single-arc structure, the length of a connecting line between the leading edge point P1 of the mean camber line and the trailing edge point P2 of the mean camber line is recorded as a blade chord length C (the connecting line is a blade chord line), the value of C is preset, and the values of C corresponding to the mean camber lines of the blades at different radial positions of the fan along the radial direction of the fan from the root of the blade to the top of the blade are all the same fixed value.
Based on the invention, as shown in fig. 2, during specific design, β 2 (i.e., the root-shaped blade setting angle of the novel twisted axial-flow blade) and β 1 (i.e., the top-shaped blade setting angle of the novel twisted axial-flow blade) may be set first, as shown in fig. 3, the radial twist rule is obtained by fitting a secondary B-spline curve controlled by three control points (i.e., P3, P4, and P5), the twist degree of different radial positions in the middle of the blade is determined by the ratio L1/L2 between the B-spline curve L1 (i.e., the distance from the P4 control point to the connecting line of the P3 and the P5 control points) and L2 (i.e., the connecting line distance from the P3 control point to the P5 control point), and the blade-shaped line setting angles of the remaining different radial.
Specifically, the secondary B-spline forming the blade twisting law is controlled by three control points, wherein the abscissa of the P3 control point is 0 and is determined by the relative blade height of the cross section where the blade root is located, and the ordinate is determined by the ratio beta 2/beta 1 of the blade root setting angle beta 2 and the blade top setting angle beta 1; the abscissa of the P5 control point is 1, which is determined by the relative blade height of the cross section where the blade top is located, and the ordinate is 1, which is determined by the ratio beta 1/beta 1 of the blade top installation angle beta 1 to the blade top installation angle beta 1; the abscissa of the point P4 is determined by the relative blade height (Di-D2)/(D1-D2) of a certain section in the middle (more than or equal to 0.6 and less than or equal to 0.9 are required), and the ordinate is determined by the ratio beta i/beta 1 of the placing angle beta i of the certain section in the middle of the blade and the placing angle beta 1 of the top of the blade; the P3 control point controls the blade root setting angle, the P5 control point controls the blade top setting angle, and the P4 control point controls the blade middle setting angle, namely the twist rule. The second B-spline constituting the blade twist law is shown in FIG. 3.
As shown in fig. 2, θ 2 (i.e., the root profile blade bending angle of the novel twisted axial flow blade) and θ 1 (i.e., the tip profile blade bending angle of the novel twisted axial flow blade) are set, as shown in fig. 3, the radial twisting law is obtained by fitting a secondary B-spline curve controlled by three control points (i.e., P6, P7, and P8), the twisting degrees of different radial positions in the middle of the blade are determined by a ratio L3/L4 between a B-spline curve L3 (i.e., the distance from a P7 control point to a P6 control point connecting line and a P8 control point connecting line) and L4 (i.e., the distance from a P6 control point connecting line and a P8 control point connecting line), and the blade profile bending angles of the remaining different radial positions are obtained.
Specifically, the secondary B-spline forming the blade bending rule is controlled by three control points, wherein the abscissa of the P6 control point is 0 and is determined by the relative blade height of the section where the blade root is located, and the ordinate is determined by the ratio theta 2/theta 1 of the bending angle theta 2 of the blade root to the bending angle theta 1 of the blade top; the abscissa of the P8 control point is 1, which is determined by the relative blade height of the section where the top of the blade is located, and the ordinate is 1, which is determined by the ratio theta 1/theta 1 of the bending angle theta 1 of the top of the blade to the bending angle theta 1 of the top of the blade; the abscissa of the point P7 is determined by the relative blade height (Di-D2)/(D1-D2) of a certain section in the middle (more than or equal to 0.6 and less than or equal to 0.9 are required), and the ordinate is determined by the ratio theta i/theta 1 of the bending angle theta i of the certain section in the middle of the blade and the bending angle theta 1 of the top of the blade; the P6 control point controls the bending angle of the blade root, the P8 control point controls the bending angle of the blade top, and the P7 control point controls the bending angle of the blade middle part, namely the bending rule. The second B-spline constituting the blade bending law is shown in FIG. 3.
The method comprises the steps that the blade top installation angle and the blade root installation angle (namely beta 2/beta 1 is more than or equal to 0.44 and less than or equal to 1.63) of the axial flow fan are reasonably configured, the twisting degrees of different radial positions in the middle of the blade are limited to a certain extent (namely L1/L2 is more than or equal to 0.19 and less than or equal to 0.31), and the blade installation angles of different radial positions are determined; the bending angle of the top of the blade and the bending angle of the root of the blade of the axial flow fan are reasonably configured (namely theta 2/theta 1 is more than or equal to 1.56 and less than or equal to 2.33), the bending degrees of different radial positions in the middle of the blade are limited to a certain extent (namely L3/L4 is more than or equal to 0.125), and the bending angles of the blades at different radial positions are determined. Compiling a program on a Matlab platform to complete a blade parametric design process, and establishing mapping between blade structure parameters and the coordinates of the blade profile lines at different radial positions: and stacking blade molded lines distributed at different radial positions to obtain a fan blade space three-dimensional shape, so as to obtain a complete axial flow fan impeller. The impeller and the blade structure of the embodiment of the invention are shown in fig. 5 and 6, and loads at different positions of the blade are redistributed by reasonably setting the radial twisting and bending rules of the blade. The fan designed by the traditional mode and the fan designed by the method provided by the invention are subjected to three-dimensional modeling and numerical simulation, the internal flow field of the fan is subjected to visual processing, and the structure of the flow field at the top end of the blade is changed, the leakage flow at the top of the blade is reduced, and the leakage vortex caused by the leakage flow at the top of the blade near the suction surface of the blade is inhibited in the operation process of the blade designed based on the B-spline bending rule. The modified inner cross-sectional streamline of the blade path is shown in fig. 13 and 14.
The traditional drawing mode is adopted to design the blades of the axial flow fan, the equal-circulation-quantity twisting rule or the equal-reaction-force twisting rule is usually followed, part of the calculation process refers to an empirical formula obtained by a series of experiments, and the flow loss of the designed blades at special positions is difficult to avoid. According to the method, the parameterized design process of the blade is preferably completed through a Matlab platform compiler, and the stacking rule of different radial positions of the blades with different axial flows is accurately controlled through fitting the radial distortion rule of the blade and the radial bending rule of the blade profile by secondary B-spline. Thereby achieving the purpose of accurately controlling the modeling of the blade.
The following is a detailed analysis with reference to examples one and two. The prototype fan is an axial flow fan designed according to an equal circulation design method, the structural parameters used by the prototype fan and the two embodiments of the invention are shown in table 1, and since the prototype fan is not designed by a B-spline curve, the parameters of L1/L2, L3/L4, (Di-D2)/(D1-D2) related to the B-spline curve are marked by "-". The blade modeling comparison schematic diagram refers to fig. 4, 5 and 6. In addition, specific values of C, D1, D2, beta 2 and theta 2 are only examples and can be flexibly adjusted, and the key point of the invention lies in the bending rule related to the blade placement angle and the blade bending angle.
TABLE 1
Figure BDA0003037520530000091
Figure BDA0003037520530000101
The embodiment of the invention is applied to the axial flow fan, samples are taken for the model, aerodynamic performance test is carried out according to GB/T1236-2000 'Industrial ventilator-standardized air duct performance test', and test data are shown in tables 2 and 3.
TABLE 2
Coefficient of flow 0.170 0.226 0.283 0.339 0.396
Full pressure coefficient of the prior art 0.250 0.280 0.242 0.177 0.120
Example full pressure coefficient 0.293 0.310 0.301 0.227 0.140
EXAMPLE two Total pressure coefficient 0.287 0.311 0.330 0.273 0.179
TABLE 3
Coefficient of flow 0.170 0.226 0.283 0.339 0.396
Prior art Fan efficiency (%) 60.27 67.87 70.67 63.01 51.87
Example one Fan efficiency (%) 62.17 71.97 77.14 70.76 54.51
Example two fan efficiency (%) 58.27 66.65 75.13 72.11 57.27
Compared with the impeller in the prior art, the impeller of the axial flow fan has the advantages that the full pressure coefficients of the axial flow fans in the first embodiment and the second embodiment are improved to different degrees compared with the fan in the prior art under the condition that the flow coefficients are the same. The full pressure coefficient of the embodiment I has the same trend with the flow change as that of the impeller in the prior art, the full pressure is obviously improved under the condition of small flow, and the maximum full pressure coefficient of the impeller is improved by 10.63 percent relative to that of the impeller in the prior art; in the second embodiment, the maximum full pressure corresponds to the deviation of the flow coefficient to a large flow, the full pressure coefficient is obviously improved under a large-flow working condition, the maximum full pressure coefficient of the impeller is improved by 17.68% compared with the prior art, and a schematic diagram of a full pressure-flow coefficient curve of the fan under different working conditions refers to fig. 9. For the efficiency of the fan, the variation trend of the efficiency of the first embodiment along with the flow is the same as that of the impeller in the prior art, the efficiency of the fan is improved to a certain extent under different flows, the efficiency is improved to the maximum at the highest efficiency point, and the maximum efficiency is improved by 6.47% compared with that of the impeller in the prior art; in the second embodiment, the maximum efficiency point corresponds to a point where the flow coefficient is shifted to a large flow, the efficiency of the fan is slightly lower than that of the fan in the prior art under a small-flow working condition, the efficiency is improved to some extent under a medium-high-flow working condition, compared with the maximum efficiency of the impeller in the prior art, the maximum efficiency is improved by 4.46%, and a curve schematic diagram of the efficiency-flow coefficient of the fan under different working conditions refers to fig. 10.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims (7)

1. The axial flow blade is characterized in that the profile of the axial flow blade comprises a blade leading edge line (1), a blade pressure surface profile (2), a blade suction surface profile (3) and a blade trailing edge line (4), wherein the blade leading edge line (1) and the blade trailing edge line (4) are both arc-shaped and are used for smoothly connecting the blade pressure surface profile (2) and the blade suction surface profile (3);
recording a connecting line of a front edge point P1 and a tail edge point P2 of the mean camber line arc (5) as a blade chord line, wherein the lengths of the blade chord lines corresponding to the mean camber line arcs (5) at different radial positions of the fan are the same preset fixed values along the radial direction of the fan from the root part to the top end of the blade; the blade pressure surface molded line (2) and the blade suction surface molded line (3) are obtained by stacking according to a preset airfoil thickness rule by taking a corresponding camber arc (5) as a reference;
and, camber line circular arc (5) of the different radial positions of fan are according to specific turn rule along the fan radial, by the blade root to the blade top change, corresponding blade pressure face molded lines (2) and blade suction surface molded lines (3) along fan radial stack can obtain blade pressure face and blade suction surface, specific:
recording an included angle between a chord line of the blade and a hub line of the fan as a blade mounting angle beta, recording a diameter corresponding to a blade section at a certain radial position from the root of the blade to the top of the blade as Di, wherein the relative blade height of the blade section is (Di-D2)/(D1-D2), the blade mounting angle of the chord line of the blade on the blade section is beta i, wherein D1 is the diameter corresponding to the section where the top of the blade is located, and D2 is the diameter corresponding to the section where the root of the blade is located; and the blade chord line on the section where the blade top end is located has a blade mounting angle beta 1, the blade chord line on the section where the blade root is located has a blade mounting angle beta 2, then beta 2/beta 1 is more than or equal to 0.44 and less than or equal to 1.63, and the change curve of the ratio beta i/beta 1 along with the ratio (Di-D2)/(D1-D2) is a quadratic B-spline curve; the secondary B-spline curve is controlled by 3 control points, except 2 end point control points, the third control point is recorded as P4, and then the P4 point simultaneously satisfies the following conditions: di is more than or equal to 0.6P4D2)/(D1-D2) is not more than 0.9, and the distance between two connecting points of the change curve is recorded as L2, and the distance between P4 and the connecting line between the two connecting points of the change curve is recorded as L1, so that the L1/L2 is not less than 0.19 and not more than 0.31;
recording the central angle corresponding to the arc (5) of the mean camber line as the bending angle theta of the blade along the windIn the radial direction, the diameter corresponding to the blade section at a certain radial position is recorded as Di from the blade root to the blade top, the relative blade height of the blade section is (Di-D2)/(D1-D2), the blade bending angle of a mean camber line arc (5) on the blade section is theta i, wherein D1 is the diameter corresponding to the section where the blade top is located, and D2 is the diameter corresponding to the section where the blade root is located; recording the blade bending angle of the mean camber line arc (5) on the section where the blade top end is located as theta 1, and the blade bending angle of the mean camber line arc (5) on the section where the blade root is located as theta 2, wherein theta 2/theta 1 is more than or equal to 1.56 and less than or equal to 2.33, and the variation curve of the ratio theta i/theta 1 along with the ratio (Di-D2)/(D1-D2) is a quadratic B-spline curve; the secondary B-spline curve is controlled by 3 control points, except 2 end point control points, the third control point is recorded as P7, and then the P7 point simultaneously satisfies the following conditions: di is more than or equal to 0.6P7D2)/(D1-D2) is not more than 0.9, and the distance between the connecting line of the two end points of the change curve is L4, and the distance between P7 and the connecting line of the two end points of the change curve is L3, so that the L3/L4 is not less than 0.125 and not more than 0.23.
2. The axial-flow blade as claimed in claim 1, wherein a quadratic B-Spline curve corresponding to a variation curve of the ratio β i/β 1 with the ratio (Di-D2)/(D1-D2) is obtained by determining a P4 control point and fitting the control point by an interpolation method to obtain a quadratic B-Spline curve;
and a quadratic B-Spline curve corresponding to the change curve of the ratio theta i/theta 1 along with the ratio (Di-D2)/(D1-D2) is obtained by firstly determining a P7 control point and then fitting by an interpolation method.
3. The axial flow blade according to claim 1, wherein D2/D1 is 0.46. ltoreq.D 2/D1. ltoreq.0.52.
4. The axial flow blade as claimed in any one of claims 1 to 3, wherein the chord line lengths of the blades corresponding to the camber line arcs (5) at different radial positions of the fan are all C, and then, C/D2 is more than or equal to 0.197 and less than or equal to 0.266.
5. The axial flow blade according to any one of claims 1 to 4, wherein the axial flow blade is adapted to be disposed on an annular impeller having an outer diameter D2.
6. The axial-flow impeller with the axial-flow blades according to any one of claims 1 to 5, comprising an annular impeller and a plurality of axial-flow blades uniformly arranged on the annular impeller, wherein the profile shapes of any 2 axial-flow blades are identical.
7. An axial flow fan having the axial flow impeller according to claim 6.
CN202110447622.9A 2021-04-25 2021-04-25 Axial flow blade and axial flow fan Active CN113007135B (en)

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CN113217418A (en) * 2021-06-29 2021-08-06 中国科学院工程热物理研究所 Pneumatic appearance structure of multistage axial compressor

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CN104564804A (en) * 2013-10-22 2015-04-29 珠海格力电器股份有限公司 Wind wheel blade, cross-flow wind wheel and design method of wind wheel blade
CN104912846A (en) * 2015-07-10 2015-09-16 珠海格力电器股份有限公司 Draught fan impeller and blade skeleton line fitting method thereof as well as draught fan
CN111779707A (en) * 2020-07-20 2020-10-16 佛山市南海九洲普惠风机有限公司 Equal-thickness sweepback axial flow blade and axial flow fan
CN112160937A (en) * 2020-09-21 2021-01-01 华中科技大学 Cross-flow fan blade

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Publication number Priority date Publication date Assignee Title
KR20090005960U (en) * 2007-12-12 2009-06-17 삼성전자주식회사 Centrifugal fan and refrigerator having the same
CN104564804A (en) * 2013-10-22 2015-04-29 珠海格力电器股份有限公司 Wind wheel blade, cross-flow wind wheel and design method of wind wheel blade
CN104912846A (en) * 2015-07-10 2015-09-16 珠海格力电器股份有限公司 Draught fan impeller and blade skeleton line fitting method thereof as well as draught fan
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CN112160937A (en) * 2020-09-21 2021-01-01 华中科技大学 Cross-flow fan blade

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113217418A (en) * 2021-06-29 2021-08-06 中国科学院工程热物理研究所 Pneumatic appearance structure of multistage axial compressor

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