Cross-flow fan blade parametric modeling method based on three-dimensional reverse extraction

Abstract

The invention discloses a cross-flow fan blade parametric modeling method based on three-dimensional reverse extraction, and the method comprises the steps: fixing a rotating shaft of a cross-flow fan as a global Z axis under a three-dimensional coordinate system; the method comprises the following steps: taking any cut single blade of the cross-flow fan, rotating blade suction surface molded lines at a blade hub and a wheel cover along a rotating shaft to obtain two annular surfaces, and extracting opposite lines as a meridian plane hub line and a meridian plane wheel cover line; a flow channel contour is defined in the meridian plane two-dimensional sketch, the flow channel contour comprises a meridian plane hub line, a meridian plane wheel casing line, an inlet and an outlet, and a closed loop is formed in the meridian plane two-dimensional sketch to construct a single flow channel; a Bezier curve is used as a stacking line of blade contours to generate pressure surface molded lines and suction surface molded lines at the sections of a blade hub and a blade cover, a blade three-dimensional model is constructed through three-dimensional modeling software based on the pressure surface molded lines and the suction surface molded lines at the sections of the blade hub and the blade cover, and a hub is generated. And parameters of angles and thicknesses of the blades in the streamline direction at the wheel casing are distributed.

Description

Technical Field

[0001] The invention relates to the technical field of optimization of crossflow fan blades for household air conditioners, and in particular to a parameterized modeling method for crossflow fan blades based on three-dimensional reverse extraction. Background Art

[0002] Crossflow fans are commonly used in household air conditioners. They have the characteristics of no axial length restriction, uniform air flow and stable air volume. Blade selection is one of the key factors in the performance assessment of crossflow fans, but the geometric extraction and optimization of crossflow fan blades are very lacking.

[0003] Crossflow fan blades usually have complex three-dimensional curved surfaces, and the blade cross-section may vary at different positions. How to accurately extract the geometric parameters of the blades is a bottleneck restricting the development of optimization technology for household air-conditioning crossflow fan blades. There are two unreasonable aspects of the traditional blade parameterization method: First, the traditional blade parameterization method is based on the extraction of blade geometric parameters on a two-dimensional plane. In fact, the blades on the three-dimensional plane have different geometric parameters such as the radius of curvature and the chord length of different blade cross-sections on the thickness side. The traditional blade parameterization method cannot take this into account and is not practical. Secondly, when using the traditional blade parameterization method for blade optimization, the operation is cumbersome and difficult, which affects the efficiency of optimizing the aerodynamic performance of crossflow fan blades.

[0004] The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Summary of the invention

[0005] The present invention provides a parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction. The three-dimensional reverse extraction method can accurately and efficiently extract the three-dimensional model parameter information of the blades, greatly reducing the workload of blade analysis; through the three-dimensional parametric modeling method, the three-dimensional blade design is optimized, thereby more scientifically improving the aerodynamic performance of the crossflow fan blades.

[0006] A parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction includes: Step 1, fixing the rotation axis of the crossflow fan to be the global Z axis in the three-dimensional coordinate system; Step 2: Take a single blade of the crossflow fan that is truncated at random, rotate the suction surface profile of the blade at the blade hub and the wheel cover along the rotation axis to obtain two annular surfaces, cut the two annular surfaces into four regions along the YZ plane and the ZX plane respectively, retain the XY positive semi-axis partial cross section, make the retained XY positive semi-axis partial cross section perpendicular to the global ZX plane, and extract the opposite lines as the meridian hub line and the meridian wheel cover line; Step 3, create a meridian plane 2D sketch in a separate ZX plane, define the flow channel profile in the meridian plane 2D sketch, the flow channel profile includes the meridian plane hub line and the meridian plane wheel house line, the inlet and the outlet, and form a closed loop in the meridian plane 2D sketch to construct a single flow channel; Step 4: Use Bezier curve As the stacking line of the blade contour, the pressure surface and suction surface profiles at the blade hub and wheel cover sections are generated, where P(t) is the coordinate of any point of the parameterized Bezier curve; n is the order of the parameterized Bezier curve; i is the current order, i=0, 1, 2, . . . ; P i is the position vector of each vertex; B i,n (t) is the Bernstein basis function, ; t is the curve parameter variable, ; Step five, based on the pressure surface and suction surface profiles at the blade hub and wheel cover sections, construct a three-dimensional model of the blade using three-dimensional modeling software to generate the angle and thickness distribution parameters of the blade along the streamline direction at the hub and wheel shaft.

[0007] In the parametric modeling method of a crossflow fan blade based on three-dimensional reverse extraction, in step two, the meridian plane two-dimensional sketch is kept consistent with the scanned image by adjusting the angle distribution of the strands.

[0008] In the parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction, in step three, the inlet and outlet are obtained by extending the two end points of the meridian hub line and the meridian wheel cover line by a certain distance, and then connecting the upper and lower end points to supplement the inlet and outlet pipe sections to form a closed loop.

[0009] In the parametric modeling method of a crossflow fan blade based on three-dimensional reverse extraction, in step three, the inlet and outlet are respectively extended along the leading edge and trailing edge of the crossflow fan blade, so that the airflow enters from the inlet, passes through the leading edge and trailing edge of the blade, and finally flows out from the outlet.

[0010] In the parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction, in step four, the Bezier curve describes the blade shape, and a line with an elliptical curvature of 1 is used to describe the hub and wheel cover at the leading edge and trailing edge of the blade.

[0011] In the parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction, in step five, the three-dimensional modeling software is BladeEditor software.

[0012] In the parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction, the meridian plane formed by the inlet, outlet, hub, wheel cover, leading edge and trailing edge is on the same sketch plane.

[0013] In the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, in step five, the Pareto optimal frontier is obtained by changing the weight factors of three conflicting objective parameters during the optimization process using a genetic algorithm.

[0014] In the parametric modeling method of a crossflow fan blade based on three-dimensional reverse extraction, a fifth-order Bezier curve is used to fit six control points to describe the changes in the blade meridian flow channel wheel cover profile.

[0015] In the parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction, the crossflow fan blades are arranged in an air conditioner.

[0016] Compared with the prior art, the present invention has the following advantages: the present invention utilizes a three-dimensional reverse extraction method to accurately and efficiently extract blade three-dimensional model parameter information, while taking into account the actual three-dimensional blades, greatly reducing the workload of blade analysis; the present invention utilizes a three-dimensional parametric modeling method to optimize the three-dimensional blade design, thereby more scientifically improving the aerodynamic performance of the crossflow fan blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] By reading the detailed description of the preferred specific embodiments below, various other advantages and benefits of the present invention will become clear to those of ordinary skill in the art. The drawings in the specification are only for the purpose of illustrating the preferred embodiments and are not considered to be limitations of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings.

[0018] In the attached picture: Figure 1 It is a schematic diagram of the process of extracting parameters of crossflow fan blades; Figure 2 It is a schematic diagram of the meridian plane of a single flow channel of a blade; Figure 3 This is a schematic diagram of the distribution of the middle arc line profile on the blade wheel cover side; Figure 4 It is a schematic diagram of the distribution of the blade installation angle along the relative meridian length on the blade wheel cover side; Figure 5 It is a schematic diagram of the distribution of the arc line profile on the blade hub side; Figure 6 It is a schematic diagram of the distribution of blade installation angles along the relative meridian length on the blade hub side; Figure 7 It is a schematic diagram of blade 3D model parameter extraction.

[0019] The present invention is further explained below in conjunction with the accompanying drawings and embodiments. DETAILED DESCRIPTION

[0020] The specific embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the specific embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0021] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the present invention, but the description is based on the general principles of the specification and is not intended to limit the scope of the present invention. The scope of protection of the present invention shall be determined by the attached claims.

[0022] To facilitate understanding of the embodiments of the present invention, further explanation will be given below by taking specific embodiments as examples in conjunction with the accompanying drawings, and each of the accompanying drawings does not constitute a limitation on the embodiments of the present invention.

[0023] like Figures 1 to 7 As shown, the parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction includes the following steps: Step 1, fixing the rotation axis of the crossflow fan to be the global Z axis in the three-dimensional coordinate system; Step 2: Take a single blade of the crossflow fan that is truncated at random, rotate the suction surface profile of the blade at the blade hub and the wheel cover along the rotation axis to obtain two annular surfaces, cut the two annular surfaces into four regions along the YZ plane and the ZX plane respectively, retain the XY positive semi-axis partial cross section, make the retained XY positive semi-axis partial cross section perpendicular to the global ZX plane, and extract the opposite lines as the meridian hub line and the meridian wheel cover line; Step 3, create a meridian plane 2D sketch in a separate ZX plane, define the flow channel profile in the meridian plane 2D sketch, the flow channel profile includes the meridian plane hub line and the meridian plane wheel house line, the inlet and the outlet, and form a closed loop in the meridian plane 2D sketch to construct a single flow channel; Step 4: Use Bezier curve As the stacking line of the blade contour, the pressure surface and suction surface profiles at the blade hub and wheel cover sections are generated, where P(t) is the coordinate of any point of the parameterized Bezier curve; n is the order of the parameterized Bezier curve; i is the current order, i=0, 1, 2, . . . ; P i is the position vector of each vertex; B i,n (t) is the Bernstein basis function, ; t is the curve parameter variable, ; Step five, based on the pressure surface and suction surface profiles at the blade hub and wheel cover sections, construct a three-dimensional model of the blade using three-dimensional modeling software to generate the angle and thickness distribution parameters of the blade along the streamline direction at the hub and wheel shaft.

[0024] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, in step two, the meridian plane two-dimensional sketch is kept consistent with the scanned image by adjusting the angle distribution of the strands.

[0025] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, in step three, the inlet and outlet are obtained by extending the two end points of the meridian hub line and the meridian wheel cover line by a certain distance, and then connecting the upper and lower end points to supplement the inlet and outlet pipe sections to form a closed loop.

[0026] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, in step three, the inlet and outlet are respectively extended along the leading edge and trailing edge of the crossflow fan blade, so that the airflow enters from the inlet, passes through the leading edge and trailing edge of the blade, and finally flows out from the outlet.

[0027] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, in step four, the Bezier curve describes the blade shape, and a line with an elliptical curvature of 1 is used to describe the hub and wheel cover at the leading edge and trailing edge of the blade.

[0028] In the preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, in step five, the three-dimensional modeling software is BladeEditor software.

[0029] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, the meridian plane formed by the inlet, outlet, hub, wheel cover, leading edge and trailing edge is on the same sketch plane.

[0030] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, in step five, the Pareto optimal frontier is obtained by changing the weight factors of three conflicting objective parameters during the optimization process using a genetic algorithm.

[0031] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, a fifth-order Bezier curve is used to fit six control points to describe the changes in the blade meridian flow channel wheel cover profile.

[0032] In a preferred implementation of the parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, the crossflow fan blades are arranged in an air conditioner.

[0033] In one embodiment, Figure 1 As shown, a parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction includes: extracting a single blade and outlining the projection lines of the blade wheel cover and hub profile on the global ZX plane; drawing the meridian hub and the inlet and outlet at both ends of the wheel cover line on the same ZX plane to form a closed curve; using a 5th-order Bezier curve to fit the blade hub and wheel cover profile and a 3rd-order Bezier curve to fit the blade installation angle distribution curve for blade parametric control.

[0034] In one embodiment, if Figure 2 As shown, the structure required for drawing the meridian profile of a single blade includes: a wheel cover rotation surface 1 of the blade 3, a hub rotation surface 2 of the blade 3, a meridian plane profile inlet area 5, a meridian plane profile outlet area 6, a meridian plane wheel cover line 4 and a meridian plane hub line 7; wherein the meridian plane refers to establishing the blade meridian plane profile line on the global ZX plane.

[0035] In one embodiment, if Figure 3 As shown in the figure, 6 control points are fitted with a 5th-order Bezier curve to describe the change of the blade meridian flow channel wheel cover profile. The blade profile coordinates calculated by the 5th-order Bezier curve blade modeling method are highly accurate and can meet actual needs to accurately calculate the mechanical properties of the fan, such as pressure drop, torque, input power, output power, and efficiency.

[0036] In one embodiment, if Figure 4 As shown, a third-order Bezier curve is used to fit 9 control points to describe the change of the blade installation angle on the blade cover side with the relative meridian length of the blade, so as to determine the change of the blade geometric angle along the blade mid-arc line.

[0037] In one embodiment, if Figure 5 As shown, a 5th-order Bezier curve is used to fit 5 control points to describe the change of the hub profile of the blade meridian flow channel. In order to ensure that the collective profile after the blade profile modification is the same as the original blade profile, the control points cannot change at the leading and trailing edges of the blade, that is, the blade Bezier curve fitting must pass through the leading and trailing edge control points of the blade.

[0038] In one embodiment, if Figure 6As shown, a third-order Bezier curve is used to fit six control points to describe the change of the blade installation angle on the blade hub side with the relative meridian length of the blade.

[0039] In one embodiment, if Figure 7 As shown, the extracted spatial control points of the hub and wheel cover profile of the blade three-dimensional model are used to generate a three-dimensional blade along the stacking line of the wheel cover and the wheel axle profile. The leading and trailing edges of the blade are depicted by an ellipse with a curvature of 1.

[0040] Although the embodiments of the present invention are described above in conjunction with the accompanying drawings, the present invention is not limited to the above specific embodiments and application fields, and the above specific embodiments are only illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can also make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present invention, all of which belong to the protection of the present invention.

Claims

1. A parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction, characterized in that: The steps include: Step 1, fixing the rotation axis of the crossflow fan to be the global Z axis in the three-dimensional coordinate system; Step 2: Take a single blade of the crossflow fan that is truncated at random, rotate the suction surface profile of the blade at the blade hub and the wheel cover along the rotation axis to obtain two annular surfaces, cut the two annular surfaces into four regions along the YZ plane and the ZX plane respectively, retain the XY positive semi-axis partial cross section, make the retained XY positive semi-axis partial cross section perpendicular to the global ZX plane, and extract the opposite lines as the meridian hub line and the meridian wheel cover line; Step 3, create a meridian plane 2D sketch in a separate ZX plane, define the flow channel profile in the meridian plane 2D sketch, the flow channel profile includes the meridian plane hub line and the meridian plane wheel house line, the inlet and the outlet, and form a closed loop in the meridian plane 2D sketch to construct a single flow channel; Step 4: Use Bezier curve As the stacking line of the blade contour, the pressure surface and suction surface profiles at the blade hub and wheel cover sections are generated, where P(t) is the coordinate of any point of the parameterized Bezier curve; n is the order of the parameterized Bezier curve; i is the current order, i=0, 1, 2, . . . ; P i is the position vector of each vertex; B i,n (t) is the Bernstein basis function, ; t is the curve parameter variable, ; Step five, based on the pressure surface and suction surface profiles at the blade hub and wheel cover sections, construct a three-dimensional model of the blade using three-dimensional modeling software to generate the angle and thickness distribution parameters of the blade along the streamline direction at the hub and wheel shaft.

2. The parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: Step 2: The meridian plane 2D sketch is made consistent with the scanned image by adjusting the angle distribution of the strands.

3. The parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: In step three, the inlet and outlet are formed by extending the two end points of the meridian hub line and the meridian wheel cover line by a certain distance, and then connecting the upper and lower end points to supplement the inlet and outlet pipe sections to form a closed loop.

4. The parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: In step three, the inlet and outlet are respectively extended along the leading edge and trailing edge of the crossflow fan blade, so that the airflow enters from the inlet, passes through the leading edge and trailing edge of the blade, and finally flows out from the outlet.

5. The parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: In step 4, the Bezier curve describes the shape of the blade, and a line with an elliptical curvature of 1 is used to describe the hub and wheel cover at the leading edge and trailing edge of the blade.

6. The parametric modeling method of crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: In step 5, the 3D modeling software is BladeEditor software.

7. The parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: The meridian plane formed by the inlet, outlet, hub, wheel cover, leading edge and trailing edge is on the same sketch plane.

8. The parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: In step five, the Pareto optimal frontier is obtained by changing the weight factors of the three conflicting objective parameters in the genetic algorithm optimization process.

9. The parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: A fifth-order Bezier curve is used to fit six control points to describe the changes in the wheel cover profile of the blade meridian flow channel.

10. The parametric modeling method for crossflow fan blades based on three-dimensional reverse extraction according to claim 1 is characterized in that: The crossflow fan blades are arranged in the air conditioner.

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