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Improved CST (Class Function/Shape Function Transformation) airfoil profile parametric method
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A parametric and airfoil technology, applied in the field of airfoil parameterization, can solve the problems of poor airfoil shape control ability and achieve the effect of improving the fitting ability
Inactive Publication Date: 2016-05-11
XIAN AIRCRAFT DESIGN INST OF AVIATION IND OF CHINA
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[0006] The purpose of the present invention is: aiming at the problem that the CST airfoil parameterization method has a poor ability to control the airfoil shape, an improved CST airfoil parameterization method with precise airfoil shape control ability is proposed to meet the requirements of modern aircraft shapes. design requirements
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Embodiment 1
[0029] The NASASC(2)-0414 airfoil is parameterized by the improved CST airfoil parameterization method, figure 2 For NASASC(2)-0414 airfoil shape. At this time, the node form is The m-order B-spline of , the spline only has 0.01 as internal nodes. Specific steps are as follows:
[0030] (1) The shape of the NASASC(2)-0414 airfoil is preprocessed by formula ③, so that the vertical coordinates of the trailing edge points of the upper and lower airfoils are 0, image 3 is the preprocessed Y(x) curve.
[0031] (2) Calculate the Ratio(x) curves of the upper and lower airfoils by formula ④, Figure 4 is the Ratio(x) curve of the upper airfoil, Figure 5 is the Ratio(x) curve of the lower airfoil.
[0032] (3) Select the node as The 8th order B-spline, Figure 6 For the B-spline basis function curve, the linear sum of the B-spline basis functions is used as the shape function of the improved CST airfoil parameterization method;
[0033] (4) Utilize the shape function to c...
Embodiment 2
[0039] Still using the improved CST airfoil parameterization method to parameterize the NASASC(2)-0414 airfoil. At this time, the node form is For B-splines of order m, node set 1 and node set 2 are not all empty. Specific steps are as follows:
[0040] (1) The shape of the NASASC(2)-0414 airfoil is preprocessed by formula ③, so that the vertical coordinates of the trailing edge points of the upper and lower airfoils are 0, image 3 is the preprocessed Y(x) curve;
[0041] (2) Calculate the Ratio(x) curves of the upper and lower airfoils by formula ④, Figure 4 is the Ratio(x) curve of the upper airfoil, Figure 5 is the Ratio(x) curve of the lower airfoil;
[0042] (3) Select the node as The 6th order B-spline, Figure 12 For the B-spline basis function curve, the linear sum of the B-spline basis functions is used as the shape function of the improved CST airfoil parameterization method;
[0043] (4) Utilize the shape function to carry out least squares fitting to t...
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Abstract
The invention discloses an improved CST (Class Function / Shape Function Transformation) airfoil profile parametric method, which comprises the following steps: firstly, preprocessing the outline of an airfoil profile; then, calculating the Ratio(x) curve of the airfoil profile; determining the node and the order of a B spline, taking the linear sum of the primary function of the B spline as a shape function of the improved CST airfoil profile parametric method; utilizing the shape function to fit the Ratio(x) curve of the airfoil profile to obtain a value of a design variable; then, calculating and fitting the airfoil profile and a maximum fitting error, if the maximum fitting error meets precision requirements, finishing parameterization, otherwise, increasing the order of the B spline, and regulating the node of the B spline; and repeating the above process until parameterization is finished.
Description
technical field [0001] The invention belongs to the field of aircraft design, in particular to airfoil parameterization method Background technique [0002] The airfoil parameterization method describes the airfoil as a form of design variable, and its ability to control the airfoil shape has an important impact on the final design result of the airfoil. The CST (Classfunction / ShapefunctionTransformation) parameterization method is a new type of parameterization method proposed by BrendaM.Kulfan of Boeing Company in the United States in 2006. , 2006, AIAA-2006-6948) and "AUniversalParametricGeometryRepresentationMethod-"CST"" (BrendaM.Kulfan, 45thAIAAAerospaceSciencesMeetingandExhibit, 2007, AIAA-2007-62). The parameterization method uses the combination of class function (Class function) and shape function (Shape function) to describe the geometric shape of two-dimensional curve. When parametrizing the airfoil, the class function of the CST parametric method is fixed, and...
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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/50
Inventor 张德虎张健
Owner XIAN AIRCRAFT DESIGN INST OF AVIATION IND OF CHINA
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