CN118260874B - Method for obtaining airfoil profile parameters of corner guide vane - Google Patents
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Abstract
The invention discloses a method for obtaining profile parameters of wing profiles of corner guide vanes, which relates to the field of pneumatic design of wind tunnel equipment, and comprises the following steps: acquiring coordinate data of a camber line and thickness distribution of a corner guide vane airfoil; and obtaining characteristic parameters of the corner guide vane airfoil according to the coordinate data, wherein the characteristic parameters comprise: the coordinates of the front edge point and the rear edge point, the maximum camber, the maximum thickness, the position and the rear edge thickness of the corner guide vane airfoil; establishing an expression of a camber line and thickness distribution curve parameterization curve, and solving and obtaining control parameters of the expression by utilizing characteristic parameters of the corner guide vane airfoil, the camber line of the corner guide vane airfoil and thickness distribution coordinate data; solving and obtaining the profile coordinates of the wing profile of the corner guide vane according to the expression and the control parameter; the invention can realize high-precision description of the wing profile of the corner guide vane by using fewer parameters, and simultaneously improve the quality of the wing profile in the space range of design parameters.
Description
Technical Field
The invention relates to the field of pneumatic design of wind tunnel equipment, in particular to a method for obtaining wing profile parameters of a corner guide vane.
Background
The corner section is a section in the wind tunnel for realizing airflow steering, and the reflux wind tunnel generally realizes circulation of airflow in the tunnel body through 4 corners of 90 degrees. In order to suppress flow separation caused by centrifugal force when the airflow turns, a blade cascade composed of a plurality of corner guide pieces is arranged in the corner section for guiding. The corner guide vane of the common wind tunnel adopts a 1/4 arc bent plate airfoil or a double-arc airfoil, the pressure distribution of the lee surface of the airfoil is not ideal, and a larger inverse pressure gradient exists. In order to avoid flow separation, the corner guide plates are arranged to be large in consistency, the airflow friction effect is obvious, and the pressure loss is high. In order to reduce the corner section pressure loss, the corner guide vane airfoil profile needs to be optimized, and the corner guide vane arrangement consistency is reduced by improving the surface pressure distribution characteristic under the premise of avoiding flow separation.
In airfoil optimization design, the airfoil profile needs to be described. The traditional discrete contour point coordinate description method can simply and directly express the curve, but the method has the advantages of more parameters, poor contour continuity and smoothness control in the contour adjustment process, low airfoil optimal design efficiency and great difficulty. The parametric curve description is carried out on the profile of the airfoil, so that the number of parameters for describing the profile of the airfoil is reduced, and the method is a basic approach for optimizing the design of the airfoil.
The corner guide vane has the design requirement of large airflow direction torsion angle, and compared with aerofoils of aviation, wind power, water power, turbine machinery and the like: the camber of the airfoil is usually above 0.15 and is far greater than that of a conventional airfoil; the leading edge point is greatly offset toward the lower airfoil surface, and there is a reversal in the direction of curvature of the lower airfoil surface. When the wing profile of the corner guide vane is described, if parametric curve description is carried out on the wing profile, the upper wing profile is a non-single curve in a rectangular coordinate system, the curvature direction of the lower wing profile is inverted for many times, and the parametric description is difficult and has large error. Therefore, the parametric description of the airfoil profile of the corner guide vane generally carries out parametric curve description on the camber line and the thickness distribution curve of the airfoil, and in the method, when parameter adjustment is carried out in a design parameter space in the design process of the airfoil with larger camber, singular points or turning easily occur on the profile of the lower airfoil, the formed profile surface is not smooth, the optimization efficiency is reduced, and even the optimization fails. In addition, the conventional airfoil profile parametric curve description method has the defects that key characteristic parameters such as camber and thickness of a design target airfoil profile are not controlled, control parameters have no clear value range, the airfoil profile curvature direction turning and position described by parameter combination are uncontrollable, and other problems are difficult to meet the parametric description and design requirements of the corner guide vane airfoil profile with large thickness and large attack angle.
Disclosure of Invention
In view of the above problems, there is an urgent need to develop a method for obtaining airfoil profile parameters of corner guide vane, which reduces the number of control parameters, improves the high-precision description of airfoil profile and improves the airfoil profile quality in the space range of design parameters, and meets the requirements of optimizing the design of airfoil profile of corner guide vane.
The invention aims to realize high-precision description of the wing profile of the corner guide vane by using fewer parameters, and simultaneously improve the quality of the wing profile in the space range of design parameters.
To achieve the above object, the present invention provides a method for obtaining airfoil profile parameters of a corner guide vane, the method comprising:
Acquiring coordinate data of a camber line and thickness distribution of a corner guide vane airfoil;
and obtaining characteristic parameters of the corner guide vane airfoil according to the coordinate data, wherein the characteristic parameters comprise: the coordinates of the front edge point and the rear edge point, the maximum camber, the maximum thickness, the position and the rear edge thickness of the corner guide vane airfoil;
Establishing an expression of a camber line and thickness distribution curve parameterization curve, and solving and obtaining control parameters of the expression by utilizing characteristic parameters of the corner guide vane airfoil, the camber line of the corner guide vane airfoil and thickness distribution coordinate data; and solving and obtaining the contour coordinates of the wing profile of the corner guide vane according to the expression and the control parameter.
By adopting the technical scheme provided by the invention, the problem of multi-value parameter curve description of the wing surface curve near the front edge point due to large camber of the wing surface of the corner guide vane wing profile is solved by describing the camber line and the thickness curve of the corner guide vane by adopting the parameter curves respectively, so that the fitting precision is high and the error is small.
By adopting the technical scheme provided by the invention, when the wing profile of the corner guide vane is designed: the segmented Bezier curves are adopted to describe the camber line and the thickness distribution curve respectively, after the control parameters such as the maximum camber, the maximum thickness, the trailing edge thickness and the like of the wing section of the corner guide vane are restrained, the number of the control parameter variables is 11 (which is equivalent to the common wing section parameter description methods such as Parsec) and the parameter space dimension is smaller; the wing profile designed by any parameter combination in the constraint space has single peak and convex distribution characteristics of an arc line and a thickness distribution curve, meets the geometric topological design requirement of the wing profile of the corner guide vane, and avoids the misunderstanding. Therefore, by adopting the technical scheme of the invention, optimization iteration of the airfoil profile of the corner guide vane is facilitated.
Preferably, the expression corresponding to the camber line parameterized curve of the corner guide vane airfoil is a first expression, and the first expression is:
；
wherein Cf is the control point of the Bezier curve of the front section of the camber line of the corner guide vane, cp is the control point of the Bezier curve of the rear section of the camber line of the corner guide vane, and the calculation modes of Cf and Cp are as follows:
；
Wherein C i=xCi+j*yCi, j is an imaginary symbol, x is an abscissa, y is an ordinate, x Ci is an abscissa of C i, y Ci is an ordinate of C i, C 0 is a complex coordinate of a leading edge point of a camber line in a corner guide vane airfoil, C 6 is a complex coordinate of a trailing edge point of a camber line in a corner guide vane airfoil, C 3 is a complex coordinate of a maximum camber position point in a corner guide vane airfoil, C 1、C2、C4 and C 5 are complex coordinates of parameterized control points, Z Cf (s, cf) is a bezier curve equation of a front section of a corner guide vane camber line controlled by s and Cf, Z Cp (s, cp) is a bezier curve equation of a rear section of a corner guide vane camber line controlled by s and Cp, s is a bezier curve position control parameter, C is a complex coordinate of a bezier curve control point of a corner guide vane camber line, subscript i is a sequence number representing different control points, and b i,3(s) is a four-time bernstant polynomial.
Preferably, based on the bezier curve dimensionless control parameter c f at the front section of the mean camber line of the corner guide vane and the bezier curve dimensionless control parameter c p at the rear section of the mean camber line of the corner guide vane, the dimensionless expressions of Cf and Cp are obtained, specifically:
；
；
Wherein Cf (c f) is a dimensionless expression of Cf, cp (c p) is a dimensionless expression of Cp, 、、、、AndAll are independent dimensionless control variable parameters with the value interval within the range of [0,1 ].
Preferably, the solution of b i,3(s) is:
。
preferably, the expression corresponding to the thickness distribution curve parameterization curve of the corner guide vane airfoil is a second expression, and the second expression is:
；
Wherein Hf is a control point of a Bezier curve at the front section of the thickness curve of the corner guide vane, hp is a control point of a Bezier curve at the rear section of the thickness curve of the corner guide vane, and expressions of Hf and Hp are respectively as follows:
；
Where H i=xHi+j*yHi, j is an imaginary symbol, x is the abscissa, y is the ordinate, x Hi is the abscissa of H i, y Hi is the ordinate of H i, H 0 is the leading edge point of the thickness profile of the corner guide vane airfoil, H 6 is the trailing edge point of the thickness profile of the corner guide vane airfoil, H 6=1+yH6,yH6 is the trailing edge thickness of the corner guide vane airfoil, H 3 is the maximum thickness position of the thickness profile of the corner guide vane airfoil, H 1、H2、H4 and H 5 are parameterized control points; Z Hf (s, hf) is Bezier curve equation of the front section of the corner deflector thickness curve controlled by s and Hf, Z Hp (s, hp) is Bezier curve equation of the rear section of the corner deflector thickness curve controlled by s and Hp, s is Bezier curve position control parameter, H is complex coordinates of Bezier curve control point of the corner deflector thickness curve, subscript i is control parameter serial number representing different control points, b i,3(s) is a four-degree Bernstein polynomial. Preferably, based on the non-dimensional control parameter h f of the bezier curve at the front section of the corner guide vane thickness curve and the non-dimensional control parameter h p of the bezier curve at the rear section of the corner guide vane thickness curve, the non-dimensional expressions of Hf and Hp are obtained, specifically:
；
；
Wherein Hf (h f) is a non-dimensional expression of Hf, hp (h p) is a non-dimensional expression of Hp, 、、、AndAll are independent dimensionless control variable parameters with the value interval within the range of [0,1 ].
Preferably, in order to avoid singularities in the lower airfoil curve, the radius of curvature at the maximum camber position should be greater than 1/2 of the maximum thickness, the method further comprising constraining the control variable parameters in the following manner:
；
Wherein y H3 is the maximum thickness of the corner baffle.
Preferably, the method further comprises solving c f、cp、hf and h p by using a nonlinear programming solver, specifically:
；
；
；
；
Where y H3 is the corner baffle maximum thickness, s.t. is a constraint, delta Cf（cf）、δCp（cp）、δHf（hf) and delta Hp（hp) are objective functions for c f、cp、hf and h p, respectively, 、、、、AndAre independent dimensionless control variable parameters with the value interval within the range of 0 and 1,、、、AndThe numerical control system is characterized in that the numerical control system is an independent dimensionless control variable parameter with a value interval within a range of [0,1], x Ci is an abscissa of C i, y Ci is an ordinate of C i, C is a complex coordinate of Bezier curve control points of mean arcs of corner guide vanes, and subscript i is a serial number and represents different control points, and specifically:
；
wherein Z Ctar and Z Htar are respectively the mean camber line and the thickness distribution curve of the airfoil of the corner guide vane, s is the Bezier curve position control parameter, ds is the differentiation of s, c f is the Bezier curve dimensionless control parameter of the front section of the mean camber line of the corner guide vane, c p is a non-dimensional control parameter of a Bezier curve at the rear section of the camber line of the corner deflector, h f is a non-dimensional control parameter of a Bezier curve at the front section of the thickness curve of the corner deflector, and h p is a non-dimensional control parameter of a Bezier curve at the rear section of the thickness curve of the corner deflector; Z Cf(s,Cf(cf)) is the bezier curve equation for the front segment of the camber line of the corner baffle controlled by s and Cf (c f), cf (c f) is a dimensionless expression of Cf, Z Cp(s,Cp(cp)) is the bezier curve equation for the rear segment of the camber line of the corner baffle controlled by s and Cp (c p), Cp (c p) is a dimensionless expression of Cp, Z Hf(s,Hf(hf)) is a Bezier curve equation for the front segment of the corner baffle thickness curve controlled by s and Hf (h f), Z Hp(s,Hp(hp)) is a Bezier curve equation for the back segment of the corner baffle thickness curve controlled by s and Hp (h p), Hf (h f) is a non-dimensional expression of Hf, and Hp (h p) is a non-dimensional expression of Hp.
Preferably, the calculating according to the expression and the control parameter to obtain the profile coordinates of the corner guide vane airfoil specifically includes:
Step a: according to the control number N of the contour points, N points of the position control parameters s E [0,1] of the incremental Bezier curve are determined;
step b: calculating to obtain a mean camber line coordinate { Z Cf(s,Cf),ZCp (s, cp) } and a thickness distribution curve discrete coordinate { Z Hf(s,Hf),ZHp (s, hp) } based on Cf, cp, hf and Hp respectively determined by c f、cp、hf and h p, and a Bezier curve position control parameter s determined by step a, wherein the mean camber line coordinate { Z Cf(s,Cf),ZCp (s, cp) } is marked as (x C,yC), the thickness distribution curve discrete coordinate { Z Hf(s,Hf),ZHp (s, hp) } is marked as (x H,yH);cf is a corner baffle mean camber line front segment Bezier curve dimensionless control parameter, c p is a corner baffle mean camber line rear segment Bezier curve dimensionless control parameter, h f is a corner baffle thickness curve front segment Bezier curve dimensionless control parameter, h p is a corner baffle thickness curve rear segment Bezier curve dimensionless control parameter, cf is a corner baffle mean camber line front segment Bezier curve control point, cp is a corner baffle mean camber curve rear segment Bezier curve point, and a corner baffle thickness curve front segment Bezier curve point;
Step c: fitting (x C,yC) by adopting a segmented spline curve to obtain a mean camber line dip angle (x C,θC) corresponding to the position of the mean camber line coordinate point;
Step d: fitting the (x H,yH) by adopting a segmented spline curve, and interpolating to obtain a thickness coordinate (x C,yHC) corresponding to the abscissa of each point of the mean camber line;
Step e: the upper airfoil surface coordinate Z up and the lower airfoil surface coordinate Z lw of the corner guide vane airfoil are obtained based on (x C,yC)、(xC,θC) and (x C,yHC), wherein x C is a mean camber line abscissa, y C is a mean camber line ordinate, y HC is a thickness corresponding to the mean camber line abscissa, and θ C is a mean camber line inclination corresponding to the mean camber line abscissa.
Preferably, the corner baffle airfoil upper airfoil coordinate Z up and the lower airfoil coordinate Z lw are calculated as follows:
。
the one or more technical schemes provided by the invention have at least the following technical effects or advantages:
the invention can realize high-precision solving of the wing profile of the corner guide vane by using fewer parameters, and simultaneously improves the quality of the wing profile in the space range of design parameters.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention;
FIG. 1 is a schematic view of a corner baffle airfoil profile
FIG. 2 is a schematic diagram of a mean camber line parameter curve;
FIG. 3 is a schematic diagram of thickness profile parameters;
FIG. 4 is a graph of a parametric description error curve of a corner baffle airfoil;
Wherein, the upper airfoil surface of the 1-corner guide vane airfoil, the lower airfoil surface of the 2-corner guide vane airfoil, the camber line of the 3-corner guide vane airfoil, the front edge point of the 4-corner guide vane airfoil, the rear edge point of the 5-corner guide vane airfoil, the maximum camber position of the camber line of the 6-corner guide vane airfoil and the maximum thickness position of the thickness distribution curve of the 7-corner guide vane airfoil.
Detailed Description
In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. In addition, the embodiments of the present invention and the features in the embodiments may be combined with each other without collision.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than within the scope of the description, and therefore the scope of the invention is not limited to the specific embodiments disclosed below.
Embodiment one;
The corner guide vane airfoil parameterization description method comprises the following steps: acquiring coordinate data of a camber line and thickness distribution of the wing profile of the corner guide vane; obtaining a plurality of characteristic parameters of the wing profile according to the coordinate data, wherein the characteristic parameters comprise coordinates of a front edge point and a rear edge point of the wing profile of the corner guide vane, the maximum camber, the maximum thickness and the position, and the thickness of the rear edge; establishing a parametric curve description method of the camber line and the thickness distribution curve, and solving control parameters of the parametric curve of the camber line and the thickness distribution curve by utilizing characteristic parameters of the airfoil of the corner guide vane, the camber line of the airfoil of the corner guide vane and thickness distribution coordinate data; and solving the wing profile coordinates of the corner guide vane according to the established parameterized curve and the control parameters.
In an alternative embodiment, the mean camber line parameterization describing method adopts a segmented bezier curve, and specifically includes:
；
wherein Cf is the control point of the Bezier curve of the front section of the camber line of the corner guide vane, cp is the control point of the Bezier curve of the rear section of the camber line of the corner guide vane, and the calculation modes of Cf and Cp are as follows:
；
Wherein C i=xCi+j*yCi, j is an imaginary symbol, x is an abscissa, y is an ordinate, x Ci is an abscissa of C i, y Ci is an ordinate of C i, C 0 is a complex coordinate of a leading edge point of a camber line in a corner guide vane airfoil, C 6 is a complex coordinate of a trailing edge point of a camber line in a corner guide vane airfoil, C 3 is a complex coordinate of a maximum camber position point in a corner guide vane airfoil, C 1、C2、C4 and C 5 are complex coordinates of parameterized control points, Z Cf (s, cf) is a bezier curve equation of a front section of a corner guide vane camber line controlled by s and Cf, Z Cp (s, cp) is a bezier curve equation of a rear section of a corner guide vane camber line controlled by s and Cp, s is a bezier curve position control parameter, C is a complex coordinate of a bezier curve control point of a corner guide vane camber line, subscript i is a sequence number representing different control points, and b i,3(s) is a four-time bernstant polynomial.
Based on the non-dimensional control parameter c f of the bezier curve at the front section of the camber line of the corner deflector and the non-dimensional control parameter c p of the bezier curve at the rear section of the camber line of the corner deflector, the non-dimensional expressions of Cf and Cp are obtained, specifically:
；
；
Wherein Cf (c f) is a dimensionless expression of Cf, cp (c p) is a dimensionless expression of Cp, 、、、、AndAll are independent dimensionless control variable parameters with the value interval within the range of [0,1 ].
Wherein b i,3(s) is a four-degree Bernstan polynomial, and the solving mode is as follows:
。
in an alternative embodiment, the solution of the thickness distribution curve parameterization adopts a segmented bezier curve, which specifically includes:
；
Wherein Hf is a control point of a Bezier curve at the front section of the thickness curve of the corner guide vane, hp is a control point of a Bezier curve at the rear section of the thickness curve of the corner guide vane, and expressions of Hf and Hp are respectively as follows:
；
Where H i=xHi+j*yHi, j is an imaginary symbol, x is the abscissa, y is the ordinate, x Hi is the abscissa of H i, y Hi is the ordinate of H i, H 0 is the leading edge point of the thickness profile of the corner guide vane airfoil, H 6 is the trailing edge point of the thickness profile of the corner guide vane airfoil, H 6=1+yH6,yH6 is the trailing edge thickness of the corner guide vane airfoil, H 3 is the maximum thickness position of the thickness profile of the corner guide vane airfoil, H 1、H2、H4 and H 5 are parameterized control points; Z Hf (s, hf) is Bezier curve equation of the front section of the corner deflector thickness curve controlled by s and Hf, Z Hp (s, hp) is Bezier curve equation of the rear section of the corner deflector thickness curve controlled by s and Hp, s is Bezier curve position control parameter, H is complex coordinates of Bezier curve control point of the corner deflector thickness curve, subscript i is control parameter serial number representing different control points, b i,3(s) is a four-degree Bernstein polynomial. In the embodiment of the invention, based on the non-dimensional control parameter h f of the front section Bezier curve of the thickness curve of the corner guide vane and the non-dimensional control parameter h p of the rear section Bezier curve of the thickness curve of the corner guide vane, a non-dimensional expression of Hf and Hp is obtained, specifically:
；
；
Wherein Hf (h f) is a non-dimensional expression of Hf, hp (h p) is a non-dimensional expression of Hp, 、、、AndAll are independent dimensionless control variable parameters with the value interval within the range of [0,1 ].
Wherein, in order to avoid the occurrence of singular points on the lower airfoil surface curve, the curvature radius of the maximum camber position is larger than 1/2 of the maximum thickness, namely, the control variable parameter meets the following nonlinear constraint requirements:
；
Wherein y H3 is the maximum thickness of the corner baffle.
In an alternative embodiment, aiming at the coincidence of the profile of the corner guide vane airfoil and the camber line and thickness distribution curve of the parameterized airfoil, a nonlinear programming solver is adopted to solve c f、cp、hf and h p, specifically:
；
；
；
；
Where y H3 is the corner baffle maximum thickness, s.t. is a constraint, delta Cf（cf）、δCp（cp）、δHf（hf) and delta Hp（hp) are objective functions for c f、cp、hf and h p, respectively, 、、、、AndAre independent dimensionless control variable parameters with the value interval within the range of 0 and 1,、、、AndThe numerical control system is characterized in that the numerical control system is an independent dimensionless control variable parameter with a value interval within a range of [0,1], x Ci is an abscissa of C i, y Ci is an ordinate of C i, C is a complex coordinate of Bezier curve control points of mean arcs of corner guide vanes, and subscript i is a serial number and represents different control points, and specifically:
；
wherein Z Ctar and Z Htar are respectively the mean camber line and the thickness distribution curve of the airfoil of the corner guide vane, s is the Bezier curve position control parameter, ds is the differentiation of s, c f is the Bezier curve dimensionless control parameter of the front section of the mean camber line of the corner guide vane, c p is a non-dimensional control parameter of a Bezier curve at the rear section of the camber line of the corner deflector, h f is a non-dimensional control parameter of a Bezier curve at the front section of the thickness curve of the corner deflector, and h p is a non-dimensional control parameter of a Bezier curve at the rear section of the thickness curve of the corner deflector; Z Cf(s,Cf(cf)) is the bezier curve equation for the front segment of the camber line of the corner baffle controlled by s and Cf (c f), cf (c f) is a dimensionless expression of Cf, Z Cp(s,Cp(cp)) is the bezier curve equation for the rear segment of the camber line of the corner baffle controlled by s and Cp (c p), Cp (c p) is a dimensionless expression of Cp, Z Hf(s,Hf(hf)) is a Bezier curve equation for the front segment of the corner baffle thickness curve controlled by s and Hf (h f), Z Hp(s,Hp(hp)) is a Bezier curve equation for the back segment of the corner baffle thickness curve controlled by s and Hp (h p), Hf (h f) is a non-dimensional expression of Hf, and Hp (h p) is a non-dimensional expression of Hp.
In an alternative embodiment, the method for obtaining the profile coordinates of the corner guide vane airfoil according to the expression and the control parameter solution specifically includes:
Step a: according to the control number N of the contour points, N points of the position control parameters s E [0,1] of the incremental Bezier curve are determined;
step b: calculating to obtain a mean camber line coordinate { Z Cf(s,Cf),ZCp (s, cp) } and a thickness distribution curve discrete coordinate { Z Hf(s,Hf),ZHp (s, hp) } based on Cf, cp, hf and Hp respectively determined by c f、cp、hf and h p, and a Bezier curve position control parameter s determined by step a, wherein the mean camber line coordinate { Z Cf(s,Cf),ZCp (s, cp) } is marked as (x C,yC), the thickness distribution curve discrete coordinate { Z Hf(s,Hf),ZHp (s, hp) } is marked as (x H,yH);cf is a corner baffle mean camber line front segment Bezier curve dimensionless control parameter, c p is a corner baffle mean camber line rear segment Bezier curve dimensionless control parameter, h f is a corner baffle thickness curve front segment Bezier curve dimensionless control parameter, h p is a corner baffle thickness curve rear segment Bezier curve dimensionless control parameter, cf is a corner baffle mean camber line front segment Bezier curve control point, cp is a corner baffle mean camber curve rear segment Bezier curve point, and a corner baffle thickness curve front segment Bezier curve point;
Step c: fitting (x C,yC) by adopting a segmented spline curve to obtain a mean camber line dip angle (x C,θC) corresponding to the position of the mean camber line coordinate point;
Step d: fitting the (x H,yH) by adopting a segmented spline curve, and interpolating to obtain a thickness coordinate (x C,yHC) corresponding to the abscissa of each point of the mean camber line;
Step e: the upper airfoil surface coordinate Z up and the lower airfoil surface coordinate Z lw of the corner guide vane airfoil are obtained based on (x C,yC)、(xC,θC) and (x C,yHC), wherein x C is a mean camber line abscissa, y C is a mean camber line ordinate, y HC is a thickness corresponding to the mean camber line abscissa, and θ C is a mean camber line inclination corresponding to the mean camber line abscissa.
The corner guide vane airfoil upper airfoil coordinate Z up and lower airfoil coordinate Z lw are calculated as follows:
。
The wing profile of a corner guide vane adopts the analytical curve design adopted by the NACA 4 digital wing profile, and the bending degree of the wing profile design is 0.15 and the thickness is 0.12. The method is adopted to carry out outline parameterization solving on the wing profile, and the capability of solving the wing profile of the corner guide vane and the error of solving results are examined.
FIG. 1 shows a schematic diagram of the corner guide vane airfoil, wherein tables 1-3 are first to third coordinate tables of a mean camber line and a thickness distribution curve of the corner guide vane airfoil, the corner guide vane airfoil is divided into an upper airfoil and a lower airfoil, a complex coordinate Z Ctar of which the equidistant center line of the airfoil curve is the mean camber line of the airfoil is expressed as Z Ctar=xCtar+i*yCtar, x Ctar is the mean camber line abscissa, and y Ctar is the mean camber line ordinate; the sum of the distances from the mean camber line to the upper airfoil surface and from the mean camber line along the direction is the local thickness, and the complex coordinate Z Htar which is the airfoil thickness distribution curve along the mean camber line abscissa is expressed as Z Htar=xCtar+i*yHtar, wherein x Htar is the thickness distribution curve abscissa, and y Htar is the thickness distribution curve ordinate.
TABLE 1 first coordinate Table of camber line and thickness distribution curve of corner guide vane airfoil
TABLE 2 second coordinate Table of camber line and thickness distribution curve of corner guide vane airfoil
TABLE 3 third coordinate Table of camber line and thickness distribution curve of corner guide vane airfoil
The proposal of the application is adopted to carry out parameterization solving on the wing profile of the corner guide vane.
The airfoil camber line leading-edge point position C 0=xC0+i*yC0 = 0, the trailing-edge point position C 6=xC6+i*yC6 = 1, the maximum thickness position C 3=xC3+i*yC3 = 0.4+0.23i. The thickness profile has a leading edge point position H 0=xH0+i*yH0 =0, a trailing edge point position H 6=xH6+i*yH6 =1+0.000252 i, and a maximum thickness position H 3=xH3+i*yH3 =0.3+0.12i.
Fig. 2 shows a schematic diagram of a parametric description of camber lines of a certain corner guide vane airfoil, which is divided into a front section and a rear section Z Cf,ZCp by a maximum camber position point C 3.
Fig. 3 shows a schematic diagram of parameterized solution of a thickness distribution curve of an airfoil of a certain corner guide vane, and the airfoil is divided into a front section and a rear section Z Hf,ZHp by a maximum thickness position point H 3.
Solving by nonlinear programming fitting to obtain control parameters c f、cp、hf and h p:
；
Defining position parameters s to be distributed between 0 and 1 in a cosine function, and counting 101 points:
；
Substituting control parameters c f、cp、hf and h p and a position parameter s into a parameterized description equation, and defining a complex coordinate Z Ctar for obtaining a parameterized description airfoil mean camber line to be expressed as Z Cres=xCres+i*yCres, wherein x Cres is an abscissa of the parameterized description airfoil mean camber line, and y Cres is an ordinate of the parameterized description airfoil mean camber line; the complex coordinate Z Hres of the parameterized airfoil thickness profile is expressed as Z Hres=xHres+i*yHres, wherein x Hres is the abscissa of the parameterized airfoil thickness profile and y Hres is the ordinate of the parameterized airfoil thickness profile; referring to tables 4-6, tables 4-6 are first through third coordinate tables parameterized to describe airfoil mean camber lines and thickness profiles;
TABLE 4 first coordinate table parametrically describing airfoil mean camber line and thickness distribution curve
TABLE 5 parameterized second coordinate table describing airfoil mean camber line and thickness distribution curve
TABLE 6 third coordinate Table parametrically describing mean camber line and thickness distribution curve of airfoil
The result of parameterizing the airfoil and corner guide vane airfoil error is shown in figure 4, wherein the abscissa is the abscissa of the corner guide vane airfoil profile coordinate system, and the ordinate is the mean camber line and thickness distribution curve percentage error; the maximum error of the camber line and the thickness distribution curve is respectively smaller than 0.001% and 0.015%.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
Claims (9)
1. A method of obtaining corner baffle airfoil profile parameters, the method comprising:
Acquiring coordinate data of a camber line and thickness distribution of a corner guide vane airfoil;
and obtaining characteristic parameters of the corner guide vane airfoil according to the coordinate data, wherein the characteristic parameters comprise: the coordinates of the front edge point and the rear edge point, the maximum camber, the maximum thickness, the position and the rear edge thickness of the corner guide vane airfoil;
Establishing an expression of a camber line and thickness distribution curve parameterization curve, and solving and obtaining control parameters of the expression by utilizing characteristic parameters of the corner guide vane airfoil, the camber line of the corner guide vane airfoil and thickness distribution coordinate data; solving and obtaining the profile coordinates of the wing profile of the corner guide vane according to the expression and the control parameter;
And solving according to the expression and the control parameter to obtain the contour coordinates of the wing profile of the corner guide vane, wherein the method specifically comprises the following steps:
Step a: according to the control number N of the contour points, N points of the position control parameters s E [0,1] of the incremental Bezier curve are determined;
Step b: calculating to obtain a mean camber line coordinate { Z Cf(s,Cf), ZCp (s, cp) } and a thickness distribution curve discrete coordinate { Z Hf(s,Hf), ZHp (s, hp) } based on Cf, cp, hf and Hp respectively determined by c f、cp、hf and h p, and a Bezier curve position control parameter s determined by step a, wherein the mean camber line coordinate { Z Cf(s,Cf), ZCp (s, cp) } is marked as (x C,yC), the thickness distribution curve discrete coordinate { Z Hf(s,Hf), ZHp (s, hp) } is marked as (x H,yH);cf is a corner baffle mean camber line front segment Bezier curve dimensionless control parameter, c p is a corner baffle mean camber line rear segment Bezier curve dimensionless control parameter, h f is a corner baffle thickness curve front segment Bezier curve dimensionless control parameter, h p is a corner baffle thickness curve rear segment Bezier curve dimensionless control parameter, cf is a corner baffle mean camber line front segment Bezier curve control point, cp is a corner baffle mean camber curve rear segment Bezier curve point, and a corner baffle thickness curve front segment Bezier curve point;
Step c: fitting (x C,yC) by adopting a segmented spline curve to obtain a mean camber line dip angle (x C,θC) corresponding to the position of the mean camber line coordinate point;
Step d: fitting the (x H,yH) by adopting a segmented spline curve, and interpolating to obtain a thickness coordinate (x C,yHC) corresponding to the abscissa of each point of the mean camber line;
Step e: the upper airfoil surface coordinate Z up and the lower airfoil surface coordinate Z lw of the corner guide vane airfoil are obtained based on (x C,yC)、(xC,θC) and (x C,yHC), wherein x C is a mean camber line abscissa, y C is a mean camber line ordinate, y HC is a thickness corresponding to the mean camber line abscissa, and θ C is a mean camber line inclination corresponding to the mean camber line abscissa.
2. The method for obtaining parameters of a corner guide vane airfoil profile according to claim 1, wherein the expression corresponding to the camber line parameterization curve of the corner guide vane airfoil is a first expression, and the first expression is:
；
wherein Cf is the control point of the Bezier curve of the front section of the camber line of the corner guide vane, cp is the control point of the Bezier curve of the rear section of the camber line of the corner guide vane, and the calculation modes of Cf and Cp are as follows:
；
Wherein C i=xCi +j*yCi, j is an imaginary symbol, x is an abscissa, y is an ordinate, x Ci is an abscissa of C i, y Ci is an ordinate of C i, C 0 is a complex coordinate of a leading edge point of a camber line in a corner guide vane airfoil, C 6 is a complex coordinate of a trailing edge point of a camber line in a corner guide vane airfoil, C 3 is a complex coordinate of a maximum camber position point in a corner guide vane airfoil, C 1、C2、C4 and C 5 are complex coordinates of parameterized control points, Z Cf (s, cf) is a bezier curve equation of a front section of a corner guide vane camber line controlled by s and Cf, Z Cp (s, cp) is a bezier curve equation of a rear section of a corner guide vane camber line controlled by s and Cp, s is a bezier curve position control parameter, C is a complex coordinate of a bezier curve control point of a corner guide vane camber line, subscript i is a sequence number representing different control points, and b i,3(s) is a four-time bernstant polynomial.
3. The method for obtaining the airfoil profile parameters of the corner guide vane according to claim 2, wherein the dimensionless expressions of Cf and Cp are obtained based on the bezier curve dimensionless control parameter c f at the front section of the mean camber line of the corner guide vane and the bezier curve dimensionless control parameter c p at the rear section of the mean camber line of the corner guide vane, specifically:
；
；
Wherein Cf (c f) is a dimensionless expression of Cf, cp (c p) is a dimensionless expression of Cp, 、、、、AndAll are independent dimensionless control variable parameters with the value interval within the range of [0,1 ].
4. A method for obtaining parameters of a corner baffle airfoil profile according to claim 2, wherein the solution of b i,3(s) is:
。
5. the method of claim 1, wherein the expression corresponding to the parameterized curve of the thickness profile of the corner guide vane airfoil is a second expression, and the second expression is:
；
Wherein Hf is a control point of a Bezier curve at the front section of the thickness curve of the corner guide vane, hp is a control point of a Bezier curve at the rear section of the thickness curve of the corner guide vane, and expressions of Hf and Hp are respectively as follows:
；
Wherein, H i=xHi +j*yHi, j is an imaginary symbol, x is an abscissa, y is an ordinate, x Hi is an abscissa of H i, y Hi is an ordinate of H i, H 0 is a corner baffle airfoil thickness profile leading edge point, H 6 is a corner baffle airfoil thickness profile trailing edge point, H 6=1+yH6,yH6 is a corner baffle airfoil trailing edge thickness, H 3 is a corner baffle airfoil thickness profile maximum thickness position, H 1、H2、H4 and H 5 are parameterized control points; z Hf (s, hf) is a Bezier curve equation of the front section of the corner deflector thickness curve controlled by s and Hf, Z Hp (s, hp) is a Bezier curve equation of the rear section of the corner deflector thickness curve controlled by s and Hp, s is a Bezier curve position control parameter, H is the complex coordinates of the Bezier curve control point of the corner deflector thickness curve, subscript i is the control parameter number representing the different control points, and b i,3(s) is a four-time Bernstein polynomial.
6. The method according to claim 5, wherein the dimensionless expressions of Hf and Hp are obtained based on the corner-deflector thickness-curve front-section bezier-curve dimensionless control parameter h f and the corner-deflector thickness-curve rear-section bezier-curve dimensionless control parameter h p, specifically:
；
；
Wherein Hf (h f) is a non-dimensional expression of Hf, hp (h p) is a non-dimensional expression of Hp, 、、、AndAll are independent dimensionless control variable parameters with the value interval within the range of [0,1 ].
7. A method of obtaining corner baffle airfoil profile parameters according to claim 3, further comprising constraining the control variable parameters in the following manner:
；
Wherein y H3 is the maximum thickness of the corner baffle.
8. A method of obtaining corner baffle airfoil profile parameters according to claim 1, further comprising solving c f、cp、hf and h p using a nonlinear programming solver, in particular:
；
；
；
；
Where y H3 is the corner baffle maximum thickness, s.t. is a constraint, delta Cf（cf）、δCp（cp）、δHf（hf) and delta Hp（hp) are objective functions for c f、cp、hf and h p, respectively, 、、、、AndAre independent dimensionless control variable parameters with the value interval within the range of 0 and 1,、、、AndThe numerical control system is characterized in that the numerical control system is an independent dimensionless control variable parameter with a value interval within a range of [0,1], x Ci is an abscissa of C i, y Ci is an ordinate of C i, C is a complex coordinate of Bezier curve control points of mean arcs of corner guide vanes, and subscript i is a serial number and represents different control points, and specifically:
；
wherein Z Ctar and Z Htar are respectively the mean camber line and the thickness distribution curve of the airfoil of the corner guide vane, s is the Bezier curve position control parameter, ds is the differentiation of s, c f is the Bezier curve dimensionless control parameter of the front section of the mean camber line of the corner guide vane, c p is a non-dimensional control parameter of a Bezier curve at the rear section of the camber line of the corner deflector, h f is a non-dimensional control parameter of a Bezier curve at the front section of the thickness curve of the corner deflector, and h p is a non-dimensional control parameter of a Bezier curve at the rear section of the thickness curve of the corner deflector; Z Cf(s,Cf(cf)) is the bezier curve equation for the front segment of the camber line of the corner baffle controlled by s and Cf (c f), cf (c f) is a dimensionless expression of Cf, Z Cp(s,Cp(cp)) is the bezier curve equation for the rear segment of the camber line of the corner baffle controlled by s and Cp (c p), Cp (c p) is a dimensionless expression of Cp, Z Hf(s,Hf(hf)) is a Bezier curve equation for the front segment of the corner baffle thickness curve controlled by s and Hf (h f), Z Hp(s,Hp(hp)) is a Bezier curve equation for the back segment of the corner baffle thickness curve controlled by s and Hp (h p), Hf (h f) is a non-dimensional expression of Hf, and Hp (h p) is a non-dimensional expression of Hp.
9. The method for obtaining parameters of corner baffle airfoil profile according to claim 1, wherein the corner baffle airfoil upper airfoil coordinate Z up and lower airfoil coordinate Z lw are calculated by:
。
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