CN113250755A - Blade profile design method based on non-uniform rational B-spline curve and blade - Google Patents
Blade profile design method based on non-uniform rational B-spline curve and blade Download PDFInfo
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- CN113250755A CN113250755A CN202110407125.6A CN202110407125A CN113250755A CN 113250755 A CN113250755 A CN 113250755A CN 202110407125 A CN202110407125 A CN 202110407125A CN 113250755 A CN113250755 A CN 113250755A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D5/00—Blades; Blade-carrying members; Heating, heat-insulating, cooling or antivibration means on the blades or the members
- F01D5/12—Blades
- F01D5/14—Form or construction
- F01D5/141—Shape, i.e. outer, aerodynamic form
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- 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
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Abstract
The present disclosure relates to a method for designing a blade profile based on non-uniform rational B-spline curves, the blade profile having a leading edge and a trailing edge, the leading edge having a leading edge point, and a blade, the method comprising: constructing a non-uniform rational B-spline curve of the leading edge camber line and a non-uniform rational B-spline curve of the trailing edge camber line to form a camber line of the airfoil; establishing a thickness profile of the leading edge, a thickness profile of the trailing edge, a non-uniform rational B-spline profile of the leading edge thickness, and a non-uniform rational B-spline profile of the trailing edge thickness to form a thickness profile of the airfoil; obtaining the molded line of the suction surface and the molded line of the pressure surface of the blade profile according to the camber line of the blade profile and the thickness distribution curve of the blade profile; and constructing the blade profile according to the profile of the suction surface and the profile of the pressure surface. By the design method, the design of the blade profile can be optimized, so that the designed blade profile has smaller aerodynamic loss and higher aerodynamic efficiency.
Description
Technical Field
The disclosure relates to the technical field of machine manufacturing, in particular to a blade profile design method based on a non-uniform rational B-spline curve and a blade.
Background
At present, in the technical field of mechanical manufacturing, a controllable diffusion blade profile is usually designed in a combined manner by adopting simple curves such as a hyperbolic spiral line, a quadratic arc curve, a high-order polynomial curve and the like, but the curvature of the blade profile cannot be in smooth transition by the design mode, so that the flow speed is locally leaped, the aerodynamic loss is increased, and the overall efficiency of a gas turbine is influenced. Meanwhile, when the controllable diffusion blade profile is designed, the blade profile is often designed in a mode of giving geometric parameters, so that the design of the blade profile is limited by a geometric modeling method, the design space is reduced, the design flexibility is poor, the number of control parameters is large, the parameter distribution is difficult to grasp, the parameter distribution is too dependent on the experience of designers, and the design process consumes a lot of time.
It is to be noted that the information disclosed in the above background section is only for enhancement of understanding of the background of the present disclosure, and thus may include information that does not constitute prior art known to those of ordinary skill in the art.
Disclosure of Invention
The invention aims to provide a blade profile design method based on a non-uniform rational B-spline curve and a blade.
The present disclosure provides, in one aspect, a method for designing a blade profile based on a non-uniform rational B-spline curve, the blade profile having a leading edge and a trailing edge, the leading edge having a leading edge point, the method comprising:
constructing a non-uniform rational B-spline curve of the leading edge camber line and a non-uniform rational B-spline curve of the trailing edge camber line to form a camber line of the airfoil;
establishing a thickness profile of the leading edge, a thickness profile of the trailing edge, a non-uniform rational B-spline profile of the leading edge thickness, and a non-uniform rational B-spline profile of the trailing edge thickness to form a thickness profile of the airfoil;
obtaining the molded line of the suction surface and the molded line of the pressure surface of the blade profile according to the camber line of the blade profile and the thickness distribution curve of the blade profile;
and constructing the blade profile according to the profile of the suction surface and the profile of the pressure surface.
In an exemplary embodiment of the present disclosure, the constructing the non-uniform rational B-spline curve of the leading edge mean camber line and the non-uniform rational B-spline curve of the trailing edge mean camber line to form a mean camber line of the airfoil comprises:
obtaining a trailing edge point of the trailing edge according to the leading edge point, the chord length of the blade profile and the mounting angle of the blade profile;
obtaining the maximum deflection point of the blade profile according to the front edge point and the rear edge point;
setting a first weighting factor and connecting the leading edge point and the point of maximum deflection according to the first weighting factor to form a non-uniform rational B-spline curve of the leading edge mean camber;
setting a second weight factor and connecting the trailing edge point and the point of maximum deflection according to the second weight factor to form a non-uniform rational B-spline curve of the trailing edge mean camber line;
connecting the non-uniform rational B-spline curve of the leading edge camber line and the non-uniform rational B-spline curve of the trailing edge camber line to form a camber line of the airfoil.
In an exemplary embodiment of the present disclosure, said deriving a point of maximum deflection of said airfoil from said leading edge point and said trailing edge point comprises:
obtaining a tangent line of a non-uniform rational B-spline curve of the camber line of the leading edge at the leading edge point according to the inlet airflow angle of the blade profile;
obtaining a tangent of the non-uniform rational B-spline curve of the trailing edge mean camber line at the trailing edge point, the tangent of the trailing edge point intersecting the tangent of the leading edge point at a first reference point;
setting a first scale factor and a second scale factor, and obtaining a maximum deflection point of the blade profile according to the leading edge point, the trailing edge point, a tangent of the leading edge point, a tangent of the trailing edge point and the first reference point;
wherein, the setting a first scale factor and a second scale factor, and obtaining the maximum deflection point of the blade profile according to the leading edge point, the trailing edge point, the tangent of the leading edge point, the tangent of the trailing edge point, and the first reference point, includes:
according to the first scale factor, the leading edge point, the trailing edge point and the first reference point, obtaining a second reference point on a tangent of the leading edge point and obtaining a third reference point on a tangent of the trailing edge point;
and obtaining the maximum deflection point of the blade profile according to the second scale factor, the second reference point and the third reference point.
In an exemplary embodiment of the present disclosure, the establishing the thickness profile of the leading edge includes:
establishing a leading edge arc having a first radius;
setting a first included angle, and establishing a first tangent which is tangent to the front edge circular arc and has the first included angle with the horizontal direction, wherein a first tangent point is arranged between the first tangent and the front edge circular arc;
setting a semi-major axis of a leading edge ellipse, and constructing a leading edge ellipse which passes through the leading edge point and is tangent to the first tangent line at the first tangent point according to the semi-major axis of the leading edge ellipse;
and according to the front edge ellipse, cutting a short arc between the front edge point and the first tangent point to obtain a thickness curve of the front edge.
In an exemplary embodiment of the present disclosure, the establishing the thickness profile of the trailing edge includes:
establishing a trailing edge arc having a second radius;
setting a second included angle, and establishing a second tangent which is tangent to the trailing edge circular arc and has the second included angle with the horizontal direction, wherein a second tangent point is arranged between the second tangent and the trailing edge circular arc;
setting a semimajor axis of a trailing edge ellipse, and constructing a trailing edge ellipse passing through the trailing edge point and tangent to the second tangent line at the second tangent point according to the semimajor axis of the trailing edge ellipse;
and intercepting a short arc between the leading edge point and the second tangent point according to the trailing edge ellipse to obtain a thickness curve of the trailing edge.
In an exemplary embodiment of the present disclosure, the establishing a non-uniform rational B-spline curve of the leading edge thickness comprises:
connecting the first tangent point and the leading edge point to obtain an auxiliary line of the non-uniform rational B-spline curve of the leading edge thickness at the first tangent point;
obtaining a fourth reference point according to the maximum thickness of the blade profile and the position of the blade profile at the maximum thickness;
establishing a tangent line of the non-uniform rational B-spline curve of the leading edge thickness at the fourth reference point, and intersecting an auxiliary line of the non-uniform rational B-spline curve of the leading edge thickness at the first tangent point at a fifth reference point;
setting a third scale factor and a fourth scale factor, and establishing a non-uniform rational B-spline curve of the leading edge thickness according to the third scale factor, the fourth reference point and the fifth reference point.
In an exemplary embodiment of the present disclosure, the establishing a non-uniform rational B-spline curve of the leading edge thickness according to the third scaling factor, the fourth reference point, the fifth reference point comprises:
acquiring a sixth reference point on the tangent line at the first tangent point according to the third scale factor, wherein the sixth reference point is located between the first tangent point and the fifth reference point;
acquiring a seventh reference point on a tangent line at the fourth reference point according to the fourth scale factor, wherein the seventh reference point is located between the fourth reference point and a fifth reference point;
setting a third weight factor, and establishing a non-uniform rational B-spline curve of the leading edge thickness according to the third weight factor, the first tangent point, the fourth reference point, the sixth reference point and the seventh reference point.
In an exemplary embodiment of the present disclosure, the establishing a non-uniform rational B-spline curve of the trailing edge thickness comprises:
connecting the second tangent point and the trailing edge point to obtain an auxiliary line of the non-uniform rational B-spline curve of the trailing edge thickness at the second tangent point;
obtaining an eighth reference point according to the maximum thickness of the blade profile and the position of the blade profile at the maximum thickness;
establishing a tangent line of the non-uniform rational B-spline curve of the trailing edge thickness at the eighth reference point, and intersecting an auxiliary line of the non-uniform rational B-spline curve of the trailing edge thickness at the second tangent point at a ninth reference point;
setting a fifth scale factor and a sixth scale factor, and establishing a non-uniform rational B-spline curve of the trailing edge thickness according to the fifth scale factor, the sixth scale factor, the eighth reference point and the ninth reference point.
In an exemplary embodiment of the present disclosure, the obtaining a profile of a suction side and a pressure side of the airfoil according to a camber line of the airfoil and a thickness profile of the airfoil includes:
extracting a thickness value of the thickness distribution curve in a first direction;
superimposing the thickness values on both sides of the mean camber line in a second direction to form a profile of the suction side and a profile of the pressure side of the airfoil;
wherein the first direction is a direction of a chord of the airfoil, and the second direction is perpendicular to the first direction.
The present disclosure provides a blade designed by using any one of the above blade profiles design methods based on non-uniform rational B-spline curves.
The technical scheme provided by the disclosure can achieve the following beneficial effects:
according to the design method of the blade profile based on the non-uniform rational B-spline curve, the mean camber line of the blade profile and the thickness distribution curve of the blade profile are constructed through the non-uniform rational B-spline curve, the problem that the curvature of the blade profile cannot be smoothly transited can be solved, the aerodynamic loss can be reduced, and the aerodynamic efficiency of the blade profile is improved. Meanwhile, by introducing the non-uniform rational B-spline curve, the design means and the design mode can be flexible and diverse, more degrees of freedom are provided for splicing, fitting and fairing operation of the blade profile curve and the curved surface, and the design space of the blade profile is further enhanced.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure. It is to be understood that the drawings in the following description are merely exemplary of the disclosure, and that other drawings may be derived from those drawings by one of ordinary skill in the art without the exercise of inventive faculty.
FIG. 1 shows a flow diagram of a method for designing a leaf profile based on a non-uniform rational B-spline curve according to an exemplary embodiment of the present disclosure;
FIG. 2 illustrates a schematic diagram of forming a mean camber line according to an exemplary embodiment of the present disclosure;
FIG. 3 illustrates a schematic diagram of a thickness profile forming a leading edge according to an exemplary embodiment of the present disclosure;
FIG. 4 illustrates a schematic view of a thickness profile forming a trailing edge according to an exemplary embodiment of the present disclosure;
FIG. 5 shows a schematic diagram of a non-uniform rational B-spline curve forming a leading edge thickness according to an exemplary embodiment of the present disclosure;
FIG. 6 shows a schematic diagram of a non-uniform rational B-spline curve forming a trailing edge thickness according to an exemplary embodiment of the present disclosure;
FIG. 7 illustrates a schematic view of the profile forming the suction side and the profile forming the pressure side according to an exemplary embodiment of the present disclosure.
Description of reference numerals:
1. a chord; 2. tangent to the leading edge point; 3. tangent to the trailing edge point; 4. a mean camber line; 5. an auxiliary line at a first tangent point; 6. a thickness profile of the leading edge; 7. an auxiliary line at the second tangent point; 8. a thickness profile of the trailing edge; 9. a tangent at a fourth reference point; 10. a non-uniform rational B-spline curve of leading edge thickness; 11. tangent line at eighth reference point; 12. a non-uniform rational B-spline curve of trailing edge thickness; 13. profile of the suction surface; 14. the profile of the pressure face.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their detailed description will be omitted.
Although relative terms, such as "upper" and "lower," may be used in this specification to describe one element of an icon relative to another, these terms are used in this specification for convenience only, e.g., in accordance with the orientation of the examples described in the figures. It will be appreciated that if the device of the icon were turned upside down, the element described as "upper" would become the element "lower". When a structure is "on" another structure, it may mean that the structure is integrally formed with the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via another structure.
The terms "a," "an," "the," "said" are used to indicate the presence of one or more elements/components/etc.; the terms "comprising" and "having" are intended to be inclusive and mean that there may be additional elements/components/etc. other than the listed elements/components/etc.; the terms "first" and "second", etc. are used merely as labels, and are not limiting on the number of their objects.
The present disclosure firstly provides a method for designing a leaf profile based on a non-uniform rational B-spline curve, which can be used for designing a leaf profile with controllable diffusion, but is not limited thereto, and can also be used for designing other leaf profiles, and can be selected according to actual needs. The blade adopting the blade profile can be used for a compressor, but is not limited to the compressor. The blade profile designed by the design method based on the non-uniform rational B spline curve provided by the disclosure can reduce aerodynamic loss and improve the aerodynamic efficiency of the blade adopting the blade profile and the overall efficiency of the compressor.
The airfoil may have a leading edge and a trailing edge, wherein the leading edge may have a leading edge point. As shown in FIGS. 1 to 7, the method for designing the leaf profile based on the non-uniform rational B-spline curve may include the following steps:
s10, constructing a non-uniform rational B-spline curve of a leading edge camber line and a non-uniform rational B-spline curve of a trailing edge camber line to form a camber line 4 of the blade profile;
s20, establishing a thickness curve 6 of the leading edge, a thickness curve 8 of the trailing edge, a non-uniform rational B-spline curve 10 of the leading edge thickness and a non-uniform rational B-spline curve 12 of the trailing edge thickness to form a thickness distribution curve of the blade profile;
s30, obtaining a molded line 13 of a suction surface and a molded line 14 of a pressure surface of the blade profile according to the camber line 4 of the blade profile and the thickness distribution curve of the blade profile;
and S40, constructing a blade profile according to the profile 13 of the suction surface and the profile 14 of the pressure surface.
The above steps are explained in detail below:
in step S10, as shown in FIG. 2, the non-uniform rational B-spline curve of the leading edge mean camber line and the non-uniform rational B-spline curve of the trailing edge mean camber line may be constructed to form the profile mean camber line 4. Specifically, the trailing edge point Q of the airfoil trailing edge can be found from the leading edge point O, the chord 1 length of the airfoil, and the stagger angle α of the airfoil. For example: a coordinate system can be established, wherein the X axis is an abscissa axis, the Y axis is an ordinate axis, the leading edge point O of the blade profile can be taken as a coordinate origin, the chord 1 length of the blade profile can be L, and the installation angle of the blade profile can be α, so that when the included angle between the chord 1 of the blade profile and the vertical direction is α, the end of the chord 1 of the blade profile far from the leading edge point O is the trailing edge point Q.
Further, a maximum deflection point D of the blade profile can be obtained according to the leading edge point O and the trailing edge point Q. Specifically, the method comprises the following steps: a tangent 2 of the non-uniform rational B-spline curve of the camber line of the leading edge at the leading edge point can be obtained according to the inlet airflow angle beta of the blade profile. For example: when the leading edge point O of the blade profile is the origin of coordinates and the inlet airflow angle is beta, a straight line with an included angle beta with the vertical direction can be made through the leading edge point O, and the straight line can be a tangent 2 of a non-uniform rational B-spline curve of a camber line in the leading edge at the leading edge point.
Further, a non-uniform rational B-spline curve of the trailing edge mean camber line may be obtained at the tangent 3 of the trailing edge point, and the tangent 3 of the trailing edge point and the tangent 2 of the leading edge point may intersect at the first reference point A. For example: the non-uniform rational B-spline of the trailing edge mean camber line may have a first derivative of 0 at the trailing edge point tangent 3, where the trailing edge point tangent 3 may be a horizontal line. It will be appreciated that a horizontal line can be drawn through the trailing edge point Q, such that the horizontal line is a tangent 3 to the non-uniform rational B-spline curve of the trailing edge mean camber line at the trailing edge point.
The tangent 2 of the non-uniform rational B-spline curve of the leading edge mean camber line at the leading edge point and the tangent 3 of the non-uniform rational B-spline curve of the trailing edge mean camber line are extended to intersect at a point, which is the first reference point A.
Next, a first scaling factor K may be set1And a second scale factor K2And obtaining a maximum deflection point D of the blade profile according to the leading edge point O, the trailing edge point Q, the tangent line 2 of the leading edge point, the tangent line 3 of the trailing edge point and the first reference point A. Specifically, the method comprises the following steps: may be based on a first scale factor K1Leading edge point O, trailing edge point Q and first reference point a result in a second reference point B on tangent 2 of the leading edge point and a third reference point C on tangent 3 of the trailing edge point. For example: the first scale factor K1The ratio of the distance between the leading edge point O and the second reference point B to the distance between the second reference point B and the first reference point a, or the ratio of the distance between the trailing edge point Q and the third reference point C to the distance between the third reference point C and the first reference point a. Thus, by the first scale factor K1It is possible to obtain exactly the second reference point B on the tangent 2 of the leading point and exactly the third reference point C on the tangent 3 of the trailing point.
Further, it can be based on a second scale factor K2And obtaining a maximum deflection point D of the blade profile by the second reference point B and the third reference point C. For example: the second scale factor K2The distance between the second reference point B and the point of maximum deflection D and the distance between the third reference point C and the point of maximum deflection D may be used. Thus, by the second scale factor K2And the maximum deflection point D of the blade profile can be accurately obtained.
A first weighting factor may be set and the leading edge point O and the point of maximum deflection D are connected according to the first weighting factor to form a non-uniform rational B-spline curve of the leading edge mean camber. Meanwhile, a second weighting factor may be set and the trailing edge point Q and the point of maximum deflection D are connected according to the second weighting factor to form a non-uniform rational B-spline curve of the trailing edge mean camber.
It should be noted that the value of the first weighting factor may be the same as the value of the second weighting factor, but may also be different, and this is not limited in this disclosure, and may be set according to actual needs. In addition, the change of the weight factor can change the curvature of the non-uniform rational B-spline curve, and when the weight factor is 0, the non-uniform rational B-spline curve is a straight line; when the weighting factor is greater than 0, the non-uniform rational B-spline curve is a curved line, and the curvature of the non-uniform rational B-spline curve gradually increases as the weighting factor increases.
Therefore, the design means and the design mode of the method are more flexible and diversified by using the non-uniform rational B-spline curve, more freedom degrees are provided for the splicing, fitting and fairing operation of the curve and the curved surface, the regulation and control capability of the curve of the blade profile is improved, and the design flexibility and the design space of the blade profile are further improved.
Further, the non-uniform rational B-spline curve of the leading edge mean curve and the non-uniform rational B-spline curve of the trailing edge mean curve may be connected to form a mean curve of the blade profile. It should be noted that. When connecting the non-uniform rational B-spline curve of the leading edge mean camber line and the non-uniform rational B-spline curve of the trailing edge mean camber line, it is necessary to connect the end points of the two non-uniform rational B-spline curves at the point D of maximum deflection.
In step S20, a leading edge thickness curve 6, a trailing edge thickness curve 8, a leading edge thickness non-uniform rational B-spline curve 10, and a trailing edge thickness non-uniform rational B-spline curve 12 may be established to form a thickness profile of the airfoil.
Specifically, as shown in FIG. 3, a first radius r may be established1Is set to a first included angle lambda1And a first included angle lambda is formed between the arc tangent with the front edge and the horizontal direction1Wherein there may be a first tangent point E between the first tangent and the leading edge arc.
The semi-major axis of the leading edge ellipse may then be set and a leading edge ellipse passing through the leading edge point O and tangent to the first tangent line at the first tangent point E may be constructed from the semi-major axis of the leading edge ellipse. For example: the analytic expression of the front edge ellipse can be obtained according to the major semi-axis and the first tangent point E of the front edge arc, and the front edge ellipse can be obtained according to the analytic expression of the front edge ellipse.
From the above-mentioned leading edge ellipse, a short arc between the leading edge point O and the first tangent point E can be taken to obtain the thickness curve 6 of the leading edge. It will be appreciated that in the leading edge ellipse there are two arcs between the leading edge point O and the first tangent point E, the shorter of which is the short arc described above.
In addition, as shown in FIG. 4, a second radius r may be established2Is set to a second included angle lambda2And a second included angle lambda is formed between the second included angle lambda and the horizontal direction and is tangent to the arc of the trailing edge2Wherein there may be a second tangent point F between the second tangent line and the trailing arc.
The semi-major axis of the trailing edge ellipse may then be set and the trailing edge ellipse passing through the trailing edge point Q and tangent to the second tangent at the second tangent point F may be constructed from the semi-major axis of the trailing edge ellipse. For example: the analytic expression of the trailing edge ellipse can be obtained according to the semiaxis of the trailing edge arc and the second tangent point, and the trailing edge ellipse can be obtained according to the analytic expression of the trailing edge ellipse.
From the trailing edge ellipse described above, a short arc between the trailing edge point Q and the second tangent point F can be taken to obtain the thickness curve 8 of the trailing edge. It will be appreciated that in the trailing edge ellipse there are two arcs between the trailing edge point Q and the second tangent point F, the shorter of which is the short arc described above.
Further, as shown in fig. 5, the first tangent point E and the leading edge point O may be connected to obtain an auxiliary line 5 of the non-uniform rational B-spline curve of the leading edge thickness at the first tangent point.
And obtaining a fourth reference point G according to the maximum thickness of the blade profile and the position S of the blade profile at the maximum thickness. It should be noted that, since the thickness of the blade profile needs to be superimposed on the mean camber line 4 in the later step, and the mean camber line 4 is located at the middle position of the blade profile, half of the maximum thickness of the blade profile is needed to obtain the fourth reference point G here. Namely: the position S of the blade profile at the maximum thickness position is the abscissa of the fourth reference point G, and half of the maximum thickness of the blade profile is the ordinate of the fourth reference point G.
After the fourth reference point G is obtained, a tangent 9 of the non-uniform rational B-spline curve 10 of the leading edge thickness at the fourth reference point may be established and intersected with the auxiliary line 5 of the non-uniform rational B-spline curve 10 of the leading edge thickness at the first tangent point at the fifth reference point H.
A third scale factor K may be set3And a fourth scale factorK4And according to a third scale factor K3A fourth scale factor K4A fourth reference point G, a fifth reference point H establishes a non-uniform rational B-spline curve 10 of leading edge thickness. Specifically, the method comprises the following steps:
may be based on a third scaling factor K3A sixth reference point I is acquired on the auxiliary line 5 at the first tangent point, which may be located between the first tangent point E and the fifth reference point H. For example: the third scale factor K3May be a ratio of a distance between the first tangent point E to the sixth reference point I to a distance between the fifth reference point H to the sixth reference point I. Therefore, according to the distance from the first tangent point E to the fifth reference point H, the sixth reference point I can be obtained.
May be based on a fourth scaling factor K4A seventh reference point J is obtained on the tangent 9 at the fourth reference point, which may be located between the fourth reference point G and the fifth reference point H. For example: the fourth scale factor K4May be a ratio of a distance between the fourth reference point G to the seventh reference point J to a distance between the fifth reference point H to the seventh reference point J. Thus, the seventh reference point J can be obtained according to the distance between the fourth reference point G and the fifth reference point H.
A third weighting factor may be set and a non-uniform rational B-spline curve 10 of leading edge thickness may be established based on the third weighting factor, the first tangent point E, the fourth reference point G, the sixth reference point I, and the seventh reference point J. It should be noted that the pattern of the non-uniform rational B-spline curve of the leading edge thickness is changed by changing the value of the third weighting factor.
Further, as shown in fig. 6, the second tangent point F and the trailing edge point Q may be connected to obtain the auxiliary line 7 of the non-uniform rational B-spline curve 12 of the trailing edge thickness at the second tangent point.
And obtaining an eighth reference point M according to the maximum thickness of the blade profile and the position S of the blade profile at the maximum thickness. It should be noted that, since the thickness of the blade profile needs to be superimposed on the mean camber line 4 in the later step, and the mean camber line 4 is located at the middle position of the blade profile, half of the maximum thickness of the blade profile is needed to obtain the eighth reference point M here. Namely: the position of the blade profile at the maximum thickness position is the abscissa of the eighth reference point M, and half of the maximum thickness of the blade profile is the ordinate of the eighth reference point M.
After the eighth reference point M is obtained, a tangent line 11 of the non-uniform rational B-spline curve of the trailing edge thickness at the eighth reference point can be established and intersected with the auxiliary line 7 of the non-uniform rational B-spline curve 12 of the trailing edge thickness at the second tangent point at the ninth reference point N.
A fifth scale factor K may be set5And a sixth scale factor K6And according to a fifth scaling factor K5A sixth scale factor K6An eighth reference point M, a ninth reference point N establish a non-uniform rational B-spline curve 12 of trailing edge thickness. Specifically, the method comprises the following steps:
may be based on a fifth scaling factor K5A tenth reference point P is obtained on the auxiliary line 7 at the second tangent point, which may be located between the second tangent point F and the ninth reference point N. For example: the fifth scale factor K5May be a ratio of a distance between the second tangent point F to the tenth reference point P to a distance between the ninth reference point N to the tenth reference point P. Thus, the tenth reference point P may be obtained according to the distance from the second tangent point F to the ninth reference point N.
May be based on a sixth scaling factor K6An eleventh reference point R is obtained on the tangent 11 at the eighth reference point, which may be located between the eighth reference point M and the ninth reference point N. For example: the sixth scale factor K6May be a ratio of a distance between the eighth reference point M to the eleventh reference point R to a distance between the ninth reference point N to the eleventh reference point R. Thus, the eleventh reference point R may be obtained according to a distance between the eighth reference point M and the ninth reference point N.
A fourth weighting factor may be set and the non-uniform rational B-spline curve 12 for the trailing edge thickness may be established based on the fourth weighting factor, the second tangent point F, the eighth reference point M, the tenth reference point p, and the eleventh reference point R. It should be noted that the pattern of the non-uniform rational B-spline curve 12 for the trailing edge thickness is varied by varying the value of the fourth weighting factor.
The leading edge thickness profile 6, the trailing edge thickness profile 8, the leading edge thickness non-uniform rational B-spline curve 10, and the trailing edge thickness non-uniform rational B-spline curve 12 may be interconnected to form a profile thickness profile. Specifically, one end of the front edge thickness curve 6 where the first tangent point E is located may be connected to one end of the front edge thickness non-uniform rational B-spline curve 10 where the first tangent point E is located, one end of the front edge thickness non-uniform rational B-spline curve 10 where the fourth reference point G is located may be connected to one end of the rear edge thickness non-uniform rational B-spline curve 12 where the eighth reference point M is located, and finally one end of the rear edge thickness non-uniform rational B-spline curve 12 where the second tangent point F is located may be connected to one end of the rear edge thickness curve 8 where the second tangent point F is located, so as to finally form the leaf-shaped thickness distribution curve. The connection sequence of the curves is not limited in the present disclosure, and can be adjusted according to actual needs.
In addition, the present disclosure compares the first scale factor K1A second scale factor K2A third scale factor K3A fourth scale factor K4A fifth scale factor K5A sixth scale factor K6Specific numerical values of the first weight factor, the second weight factor, the third weight factor and the fourth weight factor are not limited, and all the numerical values can be selected according to actual needs in a design process, and are within the protection scope of the disclosure.
In step S30, as shown in fig. 7, the profile 13 of the suction surface and the profile 14 of the pressure surface of the airfoil may be obtained from the camber line 4 of the airfoil and the thickness profile of the airfoil. Specifically, the method comprises the following steps:
the thickness values of the thickness profile in a first direction W, which may be the chord 1 direction of the profile, may be extracted. For example: the thickness profile of the blade profile may be divided in the first direction W with the chord 1 of the blade profile as a coordinate axis to form a plurality of first division points. Each first division point may have a corresponding coordinate on the axis of the chord 1. The method for obtaining the coordinate value of the first dividing point on the chord 1 may be: and an auxiliary line is made along the second direction Z through the first dividing point, the auxiliary line is extended and intersected with the coordinate axis, and therefore the value corresponding to the intersection of the auxiliary line and the coordinate axis is the coordinate value of the first dividing point on the chord 1. The second direction is perpendicular to the first direction.
Further, the camber line 4 of the blade profile may be divided in the first direction W with the chord 1 of the blade profile as a coordinate axis to form a plurality of second division points T. And coordinate values on the chord 1 of each second division point T are acquired. The method for obtaining the coordinate value of the second division point T on the chord 1 will not be described in detail, and the method for obtaining the coordinate value of the first division point T on the chord 1 will be described in detail.
Furthermore, the thickness values may be superimposed on both sides of the camber line 4 in the second direction Z to form a profile line 13 of the suction side and a profile line 14 of the pressure side of the profile. Specifically, the method comprises the following steps:
the first division points and the second division points T having the same coordinate value on the chord 1 may be in one-to-one correspondence, and the thickness value corresponding to each first division point is superimposed at the second division point T corresponding thereto along the second direction Z, so as to form a first superimposed point U and a second superimposed point V, where the first superimposed point U and the second superimposed point V are located at two sides of the central arc 4, respectively. Finally, all the first superposition points U are connected one by one to form the molded line 13 of the suction surface of the blade profile, and all the second superposition points V are connected one by one to form the molded line 14 of the pressure surface of the blade profile.
In step S40, a profile may be constructed from the profile 13 of the suction side and the profile 14 of the pressure side as described above. Specifically, the shape of one longitudinal section of the airfoil can be obtained by the profile 13 of the suction side and the profile 14 of the pressure side, and the airfoil can be constructed according to the shape of the longitudinal section, thereby completing the design of the airfoil.
In addition, the present disclosure may also program the above-described steps to generate a computer program, and store it in a computer readable medium. All the parameters used in the above steps can be input into the program, and the above steps are automatically run by the program, so that the shape of the profile 13 of the suction surface, the shape of the profile 14 of the pressure surface and the shape of the airfoil are automatically generated.
In another aspect of the present disclosure, a blade is provided, which may be a blade profile designed by the above-mentioned method for designing a blade based on a non-uniform rational B-spline curve.
The blade profile designed by the blade profile design method can solve the problem that the curvature of the blade profile cannot be smoothly transited, can reduce aerodynamic loss, and improves the aerodynamic efficiency of the blade adopting the blade profile. Meanwhile, due to the fact that the non-uniform rational B-spline curve is introduced in the process of designing the blade profile, the design means and the design mode of the blade profile are flexible and diverse, more degrees of freedom are provided for splicing, fitting and fairing operation of the blade profile curve and the curved surface of the blade, the design space of the blade profile is further enhanced, and meanwhile the design space of the blade is enhanced.
Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the disclosure disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of the disclosure following, in general, the principles of the disclosure and including such departures from the present disclosure as come within known or customary practice within the art to which the disclosure pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the disclosure being indicated by the following claims.
Claims (10)
1. A method of designing a bucket based on a non-uniform rational B-spline curve, the bucket having a leading edge and a trailing edge, the leading edge having a leading edge point, the method comprising:
constructing a non-uniform rational B-spline curve of the leading edge camber line and a non-uniform rational B-spline curve of the trailing edge camber line to form a camber line of the airfoil;
establishing a thickness profile of the leading edge, a thickness profile of the trailing edge, a non-uniform rational B-spline profile of the leading edge thickness, and a non-uniform rational B-spline profile of the trailing edge thickness to form a thickness profile of the airfoil;
obtaining the molded line of the suction surface and the molded line of the pressure surface of the blade profile according to the camber line of the blade profile and the thickness distribution curve of the blade profile;
and constructing the blade profile according to the profile of the suction surface and the profile of the pressure surface.
2. The method of claim 1, wherein the constructing the non-uniform rational B-spline curve of the leading edge mean camber line and the non-uniform rational B-spline curve of the trailing edge mean camber line to form a mean camber line of the airfoil comprises:
obtaining a trailing edge point of the trailing edge according to the leading edge point, the chord length of the blade profile and the mounting angle of the blade profile;
obtaining the maximum deflection point of the blade profile according to the front edge point and the rear edge point;
setting a first weighting factor and connecting the leading edge point and the point of maximum deflection according to the first weighting factor to form a non-uniform rational B-spline curve of the leading edge mean camber;
setting a second weight factor and connecting the trailing edge point and the point of maximum deflection according to the second weight factor to form a non-uniform rational B-spline curve of the trailing edge mean camber line;
connecting the non-uniform rational B-spline curve of the leading edge camber line and the non-uniform rational B-spline curve of the trailing edge camber line to form a camber line of the airfoil.
3. The method of claim 2, wherein said deriving a point of maximum deflection for said airfoil from said leading edge point and said trailing edge point comprises:
obtaining a tangent line of a non-uniform rational B-spline curve of the camber line of the leading edge at the leading edge point according to the inlet airflow angle of the blade profile;
obtaining a tangent of the non-uniform rational B-spline curve of the trailing edge mean camber line at the trailing edge point, the tangent of the trailing edge point intersecting the tangent of the leading edge point at a first reference point;
setting a first scale factor and a second scale factor, and obtaining a maximum deflection point of the blade profile according to the leading edge point, the trailing edge point, a tangent of the leading edge point, a tangent of the trailing edge point and the first reference point;
wherein, the setting a first scale factor and a second scale factor, and obtaining the maximum deflection point of the blade profile according to the leading edge point, the trailing edge point, the tangent of the leading edge point, the tangent of the trailing edge point, and the first reference point, includes:
according to the first scale factor, the leading edge point, the trailing edge point and the first reference point, obtaining a second reference point on a tangent of the leading edge point and obtaining a third reference point on a tangent of the trailing edge point;
and obtaining the maximum deflection point of the blade profile according to the second scale factor, the second reference point and the third reference point.
4. The method of claim 1, wherein said establishing a thickness profile of said leading edge comprises:
establishing a leading edge arc having a first radius;
setting a first included angle, and establishing a first tangent which is tangent to the front edge circular arc and has the first included angle with the horizontal direction, wherein a first tangent point is arranged between the first tangent and the front edge circular arc;
setting a semi-major axis of a leading edge ellipse, and constructing a leading edge ellipse which passes through the leading edge point and is tangent to the first tangent line at the first tangent point according to the semi-major axis of the leading edge ellipse;
and according to the front edge ellipse, cutting a short arc between the front edge point and the first tangent point to obtain a thickness curve of the front edge.
5. The method of claim 1, wherein said establishing a thickness profile of said trailing edge comprises:
establishing a trailing edge arc having a second radius;
setting a second included angle, and establishing a second tangent which is tangent to the trailing edge circular arc and has the second included angle with the horizontal direction, wherein a second tangent point is arranged between the second tangent and the trailing edge circular arc;
setting a semimajor axis of a trailing edge ellipse, and constructing a trailing edge ellipse passing through the trailing edge point and tangent to the second tangent line at the second tangent point according to the semimajor axis of the trailing edge ellipse;
and intercepting a short arc between the leading edge point and the second tangent point according to the trailing edge ellipse to obtain a thickness curve of the trailing edge.
6. The method of claim 4, wherein said creating a non-uniform rational B-spline curve of the leading edge thickness comprises:
connecting the first tangent point and the leading edge point to obtain an auxiliary line of the non-uniform rational B-spline curve of the leading edge thickness at the first tangent point;
obtaining a fourth reference point according to the maximum thickness of the blade profile and the position of the blade profile at the maximum thickness;
establishing a tangent line of the non-uniform rational B-spline curve of the leading edge thickness at the fourth reference point, and intersecting an auxiliary line of the non-uniform rational B-spline curve of the leading edge thickness at the first tangent point at a fifth reference point;
setting a third scale factor and a fourth scale factor, and establishing a non-uniform rational B-spline curve of the leading edge thickness according to the third scale factor, the fourth reference point and the fifth reference point.
7. The method of claim 6, wherein said creating a non-uniform rational B-spline curve of the leading edge thickness according to the third scaling factor, the fourth reference point, and the fifth reference point comprises:
acquiring a sixth reference point on the tangent line at the first tangent point according to the third scale factor, wherein the sixth reference point is located between the first tangent point and the fifth reference point;
acquiring a seventh reference point on a tangent line at the fourth reference point according to the fourth scale factor, wherein the seventh reference point is located between the fourth reference point and a fifth reference point;
setting a third weight factor, and establishing a non-uniform rational B-spline curve of the leading edge thickness according to the third weight factor, the first tangent point, the fourth reference point, the sixth reference point and the seventh reference point.
8. The method of claim 5, wherein said creating a non-uniform rational B-spline curve of said trailing edge thickness comprises:
connecting the second tangent point and the trailing edge point to obtain an auxiliary line of the non-uniform rational B-spline curve of the trailing edge thickness at the second tangent point;
obtaining an eighth reference point according to the maximum thickness of the blade profile and the position of the blade profile at the maximum thickness;
establishing a tangent line of the non-uniform rational B-spline curve of the trailing edge thickness at the eighth reference point, and intersecting an auxiliary line of the non-uniform rational B-spline curve of the trailing edge thickness at the second tangent point at a ninth reference point;
setting a fifth scale factor and a sixth scale factor, and establishing a non-uniform rational B-spline curve of the trailing edge thickness according to the fifth scale factor, the sixth scale factor, the eighth reference point and the ninth reference point.
9. The method for designing a airfoil based on non-uniform rational B-spline curves as claimed in claim 1, wherein said obtaining profiles of a suction side and a pressure side of said airfoil from a mean camber line of said airfoil and a thickness profile of said airfoil comprises:
extracting a thickness value of the thickness distribution curve in a first direction;
superimposing the thickness values on both sides of the mean camber line in a second direction to form a profile of the suction side and a profile of the pressure side of the airfoil;
wherein the first direction is a direction of a chord of the airfoil, and the second direction is perpendicular to the first direction.
10. A blade, characterized in that the blade is designed by the method for designing a blade profile based on non-uniform rational B-spline curves according to any one of claims 1 to 9.
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