CN110908338A - Blade profile spline reverse curvature correction method and system for turbine blade - Google Patents
Blade profile spline reverse curvature correction method and system for turbine blade Download PDFInfo
- Publication number
- CN110908338A CN110908338A CN201911144158.5A CN201911144158A CN110908338A CN 110908338 A CN110908338 A CN 110908338A CN 201911144158 A CN201911144158 A CN 201911144158A CN 110908338 A CN110908338 A CN 110908338A
- Authority
- CN
- China
- Prior art keywords
- interpolation point
- spline curve
- leaf
- control vertex
- blade
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
- G05B19/41—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by interpolation, e.g. the computation of intermediate points between programmed end points to define the path to be followed and the rate of travel along that path
- G05B19/4103—Digital interpolation
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/30—Nc systems
- G05B2219/33—Director till display
- G05B2219/33078—Error table, interpolate between two stored values to correct error
Landscapes
- Engineering & Computer Science (AREA)
- Computing Systems (AREA)
- Theoretical Computer Science (AREA)
- Human Computer Interaction (AREA)
- Manufacturing & Machinery (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Numerical Control (AREA)
Abstract
The invention provides a method and a system for correcting the reverse curvature of a blade profile spline curve of a turbine blade, wherein the method comprises the following steps: calculating to obtain node vectors and control vertex information of the leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade; calculating a second derivative vector of the leaf spline curve at each interpolation point as a curvature vector; determining a control vertex needing to be adjusted according to the curvature vector of each interpolation point, and adjusting the position information of the control vertex; and constructing an adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex. The method ensures that the control vertex of the leaf-shaped spline curve keeps convex through small adjustment of the control vertex on the leaf-shaped spline curve in a smaller adjustment range, thereby automatically eliminating the situation of reverse curvature of the leaf-shaped spline curve, remarkably improving the modeling efficiency of the leaf-shaped spline curve and reducing the influence of human factors in the modeling process.
Description
Technical Field
The invention belongs to the technical field of curve smoothing treatment, and particularly relates to a method and a system for correcting the reverse curvature of a blade profile spline curve of a turbine blade.
Background
In the turbine blade modeling process, a designer interpolates a type point by using a spline curve to generate a blade profile section line (also called a blade profile spline curve) interpolated at the type point. Due to the possible reasons of insufficient precision of profile point data, inconsistency of a modeling software and an analysis software parameterization method and the like, after a profile line of the profile section is generated, curvature vector distribution of the profile line needs to be checked, and fluctuation conditions of the profile line are observed. If the reverse condition exists in the curvature vectors of the section lines, the designer can manually adjust the original interpolation points until the curvature vectors of the section lines meet the non-fluctuation condition. The undulation of the direction of the curvature vector of the profile line can cause the surface of the model to be corrugated. The small fluctuation can reduce the surface smoothness of the model, so that the model can not meet the design requirements in the process of simulation checking calculation. The large fluctuation also causes the conditions of difficult blade processing, reduced use performance and the like. The surface of the turbine blade with curvature fluctuation is easy to generate boundary layer separation of high-speed airflow at the blade back. The boundary layer separation can enable the working state of the blades to deviate from the design working condition, the front-back pressure drop ratio of the turbine blades is reduced, the turbine cannot generate the required power, the shaft work is reduced, and the power output by the turbine to the air compressor is reduced. It follows that the flow angle to the following stages of turbine blades deviates step by step from the design conditions, resulting in a reduction in the overall performance of the turbine blades. In addition, the boundary layer separation generates increased dissipation vortex in a low-speed area, and the working efficiency of the blade is reduced.
For the condition that the smoothness of the spline curve does not meet the standard, the curve can be qualified by generally increasing the order of the curve or removing a heavy node. In the spline curve interpolation process, if the direction indicated by the curvature vector repeatedly appears on the two sides of the curve, the given curve can be re-interpolated only by adjusting the control vertex and re-parameterizing or adopting the NURBS curve. The reason for this may be that the given original interpolation point data is not qualified, or the parameterization method does not reach the standard, so that the direction of the curvature vector existing on the sample line generated according to the given point fluctuates and distributes on both sides of the curve. The reverse curvature of the curve can cause the product surface to have ripples, and for the aerodynamic surface, the ripples of the surface can increase the energy consumption and reduce the service performance of the product.
In the reverse curvature correction process of the existing spline interpolation curve, a designer often depends on observing the distribution condition of curvature vectors of section lines to manually adjust the position of an interpolation point. The method has certain randomness, can not ensure the stability of the design quality, and needs to consume certain manpower and labor, thereby reducing the modeling efficiency.
Disclosure of Invention
To overcome the above-mentioned problems, or to at least partially solve the above-mentioned problems, embodiments of the present invention provide a method and system for correcting the inverse curvature of a spline curve of a blade profile of a turbine blade.
According to a first aspect of embodiments of the present invention, there is provided a blade profile spline reverse curvature correction method for a turbine blade, including:
calculating to obtain node vectors and control vertex information of the leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade;
calculating a second derivative vector of the leaf spline curve at each interpolation point as a curvature vector;
determining a control vertex needing to be adjusted according to the curvature vector at each interpolation point;
adjusting the position information of the control vertex needing to be adjusted according to the control vertex information;
and constructing an adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex.
On the basis of the above-described embodiment, the present invention may be further modified as follows.
The step of calculating and obtaining the node vector and the control vertex information of the leaf-shaped spline curve according to the interpolation point data of the leaf-shaped spline curve of the turbine blade comprises the following steps:
calculating the parameter value of each interpolation point by adopting a preset parameterization method for the interpolation point data of the blade-shaped spline curve of the turbine blade;
calculating a node vector of the leaf spline curve according to the parameter value of each interpolation point;
and calculating to obtain the control node of the leaf-shaped spline curve according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline curve.
Further, the preset parameterization methods comprise a uniform parameterization method, an accumulated chord length parameterization method, a centripetal parameterization method and a Foley parameterization method.
Further, the calculating the parameter value of each interpolation point by using a preset parameterization method for the interpolation point data of the blade-shaped spline curve of the turbine blade comprises the following steps:
calculating the parameter value of each interpolation point by adopting a parameterization method of accumulated chord length:
wherein Q iskIs the coordinate of the kth interpolation point, | Qk-Qk-1L is the distance between the kth interpolation point and the (k-1) th interpolation point,
is the parameter value of the kth interpolation point.
Further, the calculating the node vector of the leaf spline according to the parameter value of each interpolation point includes:
u0＝…＝up＝0，um-p＝…＝um＝1，m＝n+p+1；
U＝[u0，u1，u2，……，un+p+1]，u∈[up，un+1]；
wherein m is the total number of node vectors of the leaf spline curve, n and p are positive integers, p is the frequency of the B spline basis function, n is (the number of interpolation points +1),
is the parameter value of the ith interpolation point.
Further, the step of calculating a control node of the leaf-shaped spline curve according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline curve includes:
and according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline curve, calculating and obtaining a control node of the leaf-shaped spline curve by a matrix inversion method:
wherein the content of the first and second substances,
the parameter value for the kth interpolation point,
as a value of a parameter
P-th order B-spline basis function of (Q)kIs the coordinates of the kth interpolation point.
Further, the calculating a second derivative vector of the leaf-shaped spline curve at each interpolation point as a curvature vector includes:
calculating a second derivative of each interpolation point of the leaf-shaped spline curve through the following formula, wherein the first derivative is a tangent vector of the leaf-shaped spline curve, and the second derivative is a curvature vector of the leaf-shaped spline curve:
C(k)(u)＝Ni，p-k(u)Pi (k)；
in the formula, C(k)(u) is the k-th derivative value at u as the parameter value of the interpolation point, when k is 2, C(2)(u)＝Ni，p-2(u)Pi (2)The parameter value for an interpolation point is the derivative value of order 2 at u, i.e. the curvature vector at that interpolation point.
Further, the determining the control vertex to be adjusted according to the curvature vector at each interpolation point includes:
judging whether the curvature vector direction at each interpolation point is consistent with the theoretical direction;
recording the index value of an interpolation point with the curvature vector direction inconsistent with the theoretical direction, and acquiring the index value of a control vertex related to the index value of the corresponding interpolation point, wherein an index value interval formed by the index values of the control vertex is an abnormal interval, and the control vertex in the abnormal interval is a control vertex needing to be adjusted.
Further, the adjusting the position information of the control vertex to be adjusted according to the control vertex information includes:
for any abnormal interval, judging whether the curve segment of the leaf-shaped spline curve in any abnormal interval meets a convexity-keeping condition;
if the control vertex does not meet the requirement, the span of any abnormal interval needs to be expanded, and the position information of the control vertex in the abnormal interval after the span is expanded is adjusted;
and if so, adjusting the position information of the control vertex in any abnormal interval.
Further, the constructing an adjusted leaf spline curve based on the adjusted position information of the control vertex further includes:
calculating the minimum distance between each interpolation point and the adjusted leaf-shaped spline curve, and judging whether each minimum distance is within an allowable value range;
and if not, adjusting the adjusted leaf-shaped spline curve again.
According to a second aspect of the embodiments of the present invention, there is provided a blade-profile spline reverse curvature correction system for a turbine blade, including:
the first calculation module is used for calculating and obtaining node vectors and control vertex information of the leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade;
the second calculation module is used for calculating a second derivative vector of the leaf spline curve at each interpolation point as a curvature vector;
the determining module is used for determining a control vertex needing to be adjusted according to the curvature vector at each interpolation point;
the adjusting module is used for adjusting the position information of the control vertex needing to be adjusted according to the control vertex information;
and the construction module is used for constructing the adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex.
According to a third aspect of the embodiments of the present invention, there is also provided an electronic device, including a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor calls the program instructions to execute the leaf-shaped spline reverse curvature correction method for a turbine blade provided in any one of the various possible implementations of the first aspect.
According to a fourth aspect of embodiments of the present invention, there is also provided a non-transitory computer readable storage medium storing computer instructions for causing a computer to perform the method for leaf-spline reverse curvature correction of a turbine blade provided in any one of the various possible implementations of the first aspect.
The embodiment of the invention provides a method and a system for correcting the reverse curvature of a blade-shaped spline curve of a turbine blade.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic overall flow chart of a method for correcting the inverse curvature of a blade-shaped spline curve of a turbine blade according to an embodiment of the present invention;
FIG. 2-a is a schematic view of a complete airfoil spline curve for a turbine blade;
FIG. 2-b is a schematic view of the curvature distribution of the leaf spline curve;
FIG. 2-c is an enlarged schematic view of an intermediate detail of FIG. 2-b;
FIG. 3-a is a schematic diagram of an expanded abnormal region and a schematic diagram of comparison before and after expansion;
3-b are schematic and comparative before and after adjustment diagrams for a single control vertex without the first control vertex;
3-c are schematic and pre-and post-adjustment comparison diagrams for multiple control vertices without the first control vertex;
3-d are schematic and comparative before and after adjustment diagrams including a first control vertex and for a single control vertex;
FIG. 4 is a schematic view of the inverse anomaly of the vector of curvature of a blade spline of a turbine blade;
FIG. 5 is a comparison graph of the leaf spline curves formed before and after control vertex adjustment;
FIG. 6 is a schematic view of a blade spline curve reverse curvature correction system for a turbine blade according to an embodiment of the present invention;
fig. 7 is a schematic view of an overall structure of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
In an embodiment of the present invention, a method for correcting the blade-shaped spline curve reverse curvature of a turbine blade is provided, and fig. 1 is a schematic flowchart of an overall method for correcting the blade-shaped spline curve reverse curvature of a turbine blade according to an embodiment of the present invention, where the method includes:
calculating to obtain node vectors and control vertex information of the leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade;
calculating a second derivative vector of the leaf spline curve at each interpolation point as a curvature vector;
determining a control vertex needing to be adjusted according to the curvature vector at each interpolation point;
adjusting the position information of the control vertex needing to be adjusted according to the control vertex information;
and constructing an adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex.
It can be understood that in the blade profile design of the turbine blade, in order to ensure that the curvature of the blade profile spline curve keeps convex, the finally obtained blade curved surface does not generate local shape torsion, and a smooth curved surface appearance is obtained. 2-a, 2-b and 2-c, FIG. 2-a is a complete blade profile curve of the turbine blade, and FIG. 2-b is a schematic view of the target curve curvature distribution, which is shown with the direction opposite to the direction of the curvature vector for ease of viewing; the longer the curvature vector in the curvature distribution diagram, the larger the curvature value at the point; in the figure, the intersection point of a connecting line of curvature vector end points and a target blade line is a position where the direction of curvature vectors is reversed, the blade line has an inflection point at the intersection point, and the part of detail of the circle in the figure is a position where the curvature vectors are reversed frequently and needs to be processed. 2-c is a magnified view of the middle part of detail, and it can be seen that the situation that the cursors fluctuate on both sides of the blade profile is easy to occur at the trailing edge of the blade profile.
The embodiment of the invention provides a method for correcting the reverse curvature of a leaf spline curve, aiming at solving the problem of the reverse curvature of a curve caused by unqualified original interpolation points or parameterization methods in the modeling process of the leaf spline curve.
On the basis of the above embodiment, in the embodiment of the present invention, the calculating and obtaining the node vector and the control vertex information of the leaf-shaped spline curve according to the interpolation point data of the leaf-shaped spline curve of the turbine blade includes:
calculating the parameter value of each interpolation point by adopting a preset parameterization method for the interpolation point data of the blade-shaped spline curve of the turbine blade;
calculating a node vector of the leaf spline curve according to the parameter value of each interpolation point;
and calculating to obtain the control node of the leaf-shaped spline curve according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline curve.
First, an interpolation point file of the leaf spline curve is read, the format is converted, and the leaf spline curve is rendered by a graphics library. The graphic library is a library which can convert original data into visual elements and display complex resources by using an vivid and visual expression mode for deepening understanding of a user.
And calculating the parameter value of each interpolation point by adopting a proper parameterization method for the rendered interpolation point data. The parameterization is that a parameter segmentation is determined for a group of ordered interpolation points in the leaf spline curve, and is called to carry out parameterization on the interpolation points. The general parameterization methods implemented for interpolation points are: uniform parameterization, cumulative chord length parameterization, centripetal parameterization, Foley parameterization, and the like. The embodiment of the invention uses a parameterization method for accumulating chord lengths under the condition that the control vertex distribution is more uniform.
For the interpolation point data of the blade-shaped spline curve of the turbine blade, calculating the parameter value of each interpolation point by adopting a parameterization method of accumulated chord length comprises the following steps:
where n is the number of interpolation points of the leaf spline curve, QkIs the coordinate of the kth interpolation point, | Qk-Qk-1L is the distance between the kth interpolation point and the (k-1) th interpolation point,
is the parameter value of the kth interpolation point.
On the basis of the foregoing embodiments, in an embodiment of the present invention, calculating the node vector of the leaf spline according to the parameter value of each interpolation point includes:
u0＝…＝up＝0，um-p＝…＝um＝1，m＝n+p+1；
U＝[u0，u1，u2，……，un+p+1]，u∈[up，un+1]；
wherein m is the total number of node vectors of the leaf spline curve, n and p are positive integers, p is the frequency of the B spline basis function, n is (the number of interpolation points +1),
is the parameter value of the ith interpolation point.
Wherein the content of the first and second substances,
finger ball
The index values i j, i j +1, i j +2
And (4) homogenizing and neutralizing. For example, when j is 2 and p is 3, the following is:
on the basis of the foregoing embodiments, in the embodiments of the present invention, calculating the control node of the leaf-shaped spline according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline includes:
and calculating to obtain the control vertex of the leaf-shaped spline curve by a matrix inversion method according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline curve, wherein the formula is as follows:
wherein the content of the first and second substances,
the parameter value for the kth interpolation point,
as a value of a parameter
P-th order B-spline basis function of (Q)kIs the coordinate of the kth interpolation point, PiIs the ith control vertex. According to the formula, a linear equation system of (n +1) × (n +1) can be constructed, wherein (n +1) is the number of control vertexes, and the embodiment of the invention adopts matrixAnd solving the equation set to obtain the control vertex of the leaf-shaped spline curve.
On the basis of the foregoing embodiments, in the embodiment of the present invention, calculating the second derivative vector of the leaf-type spline curve at each interpolation point as the curvature vector includes:
and solving a second derivative of each interpolation point of the leaf-shaped spline curve through the following formula, wherein the first derivative is a tangent vector of the leaf-shaped spline curve, and the second derivative is a curvature vector of the leaf-shaped spline curve:
Pi (0)＝Pi，k＝0；
C(k)(u)＝Ni，p-k(u)Pi (k)；
in the formula, C(k)(u) is the k-th derivative value at u as the parameter value of the interpolation point, when k is 2, C(2)(u)＝Ni，p-2(u)Pi (2)The parameter value for an interpolation point is the derivative value of order 2 at u, i.e. the curvature vector at that interpolation point.
On the basis of the foregoing embodiments, in an embodiment of the present invention, determining a control vertex to be adjusted according to a curvature vector at each interpolation point includes:
judging whether the curvature vector direction at each interpolation point is consistent with the theoretical direction;
recording the index value of the interpolation point with the curvature vector direction inconsistent with the theoretical direction, and acquiring the index value of the control vertex related to the corresponding index value of the interpolation point, wherein the index value interval formed by the index values of the control vertex is an abnormal interval, and the control vertex in the abnormal interval is the control vertex needing to be adjusted.
It can be understood that in the process of judging whether the direction of the curvature vector at each interpolation point is consistent with the theoretical direction, the direction of the curvature vector accords with the direction required in engineering, is perpendicular to the tangent vector of the leaf-type spline curve and points to the concave side of the leaf-type spline curve; and the curvature vector meeting the conditions is qualified, otherwise, the curvature vector is abnormal.
When the curvature vector direction at the interpolation point is inconsistent with the theoretical direction, recording the index value of the interpolation point with the curvature vector direction inconsistent with the theoretical direction, and acquiring the index value of the control vertex related to the corresponding interpolation point index value, specifically, according to the parameter value of the interpolation point with the curvature vector direction inconsistent with the theoretical direction
Calculating the vector U ═ U at the node0，u1，u2，......，un+p+1]Position [ i, i + 1] of the interval in (1)]Interval of parameter values from interpolation point [ i, i + 1]]The associated control vertex is [ P ]i-p，Pi-p+1，...，Pi]That is, the index value interval of the control vertex to be adjusted is [ i-p, i]。
On the basis of the foregoing embodiments, in an embodiment of the present invention, adjusting, according to control vertex information, position information of a control vertex that needs to be adjusted includes:
for any abnormal interval, judging whether the curve section of the leaf-shaped spline curve in any abnormal interval meets a convexity-keeping condition;
if the control vertex does not meet the requirement, the span of any abnormal interval needs to be expanded, and the position information of the control vertex in the abnormal interval after the span is expanded is adjusted;
and if so, adjusting the position information of the control vertex in any abnormal interval.
It is understood that "expanding the span of the abnormal interval" in the embodiment of the present invention means that the control vertex of the abnormal interval has no adjustment capability, and it is necessary to include the control vertex before the abnormal interval into the processing range, see fig. 3-a, where it is assumed that the original control vertex interval of the leaf-type spline curve to be adjusted is Pi、Pi+1、Pi+2And Pi+3，Pi-1And PiThe extension of the line does not guarantee that all control vertices in the original control vertex interval lie on the concave side of the leaf spline curve (P)i+3At Pi-1And PiLine extension L0The other side of) the vertex P needs to be controlledi-1Taking in the adjusting range, as the first control point of the adjusting interval, reexamining and finding the control vertex Pi-2And Pi-1Extension line L of connecting line2Can satisfy the following Pi-1All control vertexes inside are positioned on one side of the curve concave; sequentially constructing control vertexes Pi-1And Pi、Pi+1、Pi+2、……、PnIs connected with a straight line L2The line with the smallest included angle is L1(ii) a To control the vertex PiAs a starting point, the leaf-shaped spline curve is separated from PiThe curvature vector of the nearest point is the direction structure ViCalculating ViAnd L1And L2The intersection of (A) and (B) is obtained as C1And C2To find out C1、C2Midpoint P ofi' is replacing PiThe new control vertex.
The situation of adjusting the position information of the control vertex includes a plurality of situations, and the adjustment is performed for one (see fig. 3-b) to a plurality (see fig. 3-c) of points in the adjustment interval, such as the positions of the first control vertex (see fig. 3-b) not containing the leaf-shaped spline curve and the first control vertex (see fig. 3-d) containing the leaf-shaped spline curve.
In FIG. 3-b, the first control vertex P for a spline curve that does not contain a leaf is pointed0And only one control vertex needs to be adjusted: construct control vertex PiAnd Pi-1Is a connecting line L2(ii) a Sequentially constructing control vertexes PiAnd Pi+1、Pi+2、……、PnIs taken from the line L2The line with the smallest included angle is L1(ii) a To control the vertex Pi+1As a starting point, the leaf-shaped spline curve is separated from Pi+1The curvature vector of the nearest point is the direction structure V1(ii) a Calculating V1And L1And L2The intersection of (A) and (B) is obtained as C1And C2To find out C1、C2Of midpoint P'i+1To replace Pi+1The new control vertex.
In FIG. 3-c, for the first control vertex P that does not contain a leaf spline curve0And the need to adjust multiple control vertices: construct control vertex PiAnd Pi-1Is a connecting line L2(ii) a Sequentially constructing control vertexes PiAnd Pi+1、Pi+2、……、PnIs taken from the line L2The line with the smallest included angle is L1(ii) a To control the vertex Pi+1As a starting point, the leaf-shaped spline curve is upward away from the control vertex Pi+1The curvature vector of the nearest point is the direction structure Vi+1(ii) a Calculating Vi+1And L1And L2The intersection of (A) and (B) is obtained as C1And C2To find out C1、C2Of midpoint P'i+1To replace Pi+1The new control vertex. Fabricated apex P'i+1And PiOf link line L'2(ii) a Sequentially constructing control vertices P'i+1And Pi+2、……、PnIs taken from the line L'2The line with the smallest included angle is L'1(ii) a To control the vertex Pi+2As a starting point, from Pi+2The curvature vector of a point on the nearest curve is a directional structure Vi+2(ii) a Calculating Vi+2And L'1And L'2The intersection of (A) gives C'1And C'2Obtaining C'1、C′2Of midpoint P'i+2To replace Pi+1The new control vertex. The same way can recur the position of the subsequent new control vertex.
In FIG. 3-d, for the first control vertex P containing the leaf spline curve0The control vertex P is constructed in succession0And P1、P2、……、PnSo as to ensure that all the control vertexes are positioned on the concave side of the leaf-shaped spline curve, and the straight line of the concave side of the leaf-shaped spline curve is L2(ii) a To control the vertex P1As a starting point, the leaf-shaped spline curve is separated from P1The curvature vector of the nearest point is the direction structure V1(ii) a Calculating V1And L1The intersection point was P'1To replace P1The new control vertex.
And adjusting the control vertex in each abnormal interval by the method to obtain an adjusted new control vertex, and constructing the leaf spline curve based on the new control vertex.
It can be understood that, referring to fig. 4, a schematic diagram of the inverse anomaly of the curvature vector of the leaf-type spline curve is shown, where P is the control vertex, T is the tangent vector, V is the curvature vector, and VR is a connecting line between the control vertex and the reference point, and referring to fig. 5, a comparison diagram of the leaf-type spline curve before and after adjustment is shown.
On the basis of the foregoing embodiments, in an embodiment of the present invention, after constructing the adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex, the method further includes:
calculating the minimum distance between each interpolation point and the adjusted leaf-shaped spline curve, and judging whether each minimum distance is within an allowable value range;
and if not, adjusting the adjusted leaf-shaped spline curve again.
It is understood that, by constructing the adjusted spline curve according to the above-described embodiment, the minimum distance between each interpolation point and the adjusted leaf-shaped spline curve is calculated for the original interpolation points, and whether each minimum distance is within the allowable value range is determined. If the minimum distance between the original interpolation point and the adjusted leaf-shaped spline curve exceeds the allowable value range, the difference between the adjusted leaf-shaped spline curve and the leaf-shaped spline curve before adjustment is larger, so that the adjusted leaf-shaped spline curve needs to be adjusted again, the adjusted leaf-shaped spline curve is ensured to be relatively close to the leaf-shaped spline curve before adjustment, and the minimum distance between the original interpolation point and the adjusted leaf-shaped spline curve is embodied to be within the allowable range.
Through the embodiments, in the interpolation process of the leaf spline curve, the curvature vector of each point on the leaf spline curve is maintained to point to the concave direction of the leaf spline curve through small adjustment of the control vertex, and the fluctuation of the leaf spline curve is eliminated, so that the leaf spline curve has the characteristic of smooth change; meanwhile, the method has the advantages of reducing manual intervention in the modeling process of the leaf spline curve, improving the modeling stability of the leaf spline curve and the like, along with small calculation amount.
The blade-type spline curve reverse curvature correction method for the turbine blade provided by the embodiment of the invention can be implemented by adopting a computer program, and comprises the following specific steps:
reading and rendering an interpolation point file, and calculating a node vector and a control vertex of the leaf spline curve, wherein the method specifically comprises the following steps:
reading a file path by adopting a C + + data stream function ifstream input (str _ path, ios:: in), judging the effectiveness of the path, extracting and storing coordinate information of an interpolation point, and rendering the interpolation point data by adopting a VTK visual pipeline.
And calculating the distance Length [ i ] between adjacent interpolation points and the sum TotalLength of all distance values, and normalizing the distance values, wherein the parameter value at the interpolation point i is Length Temp [ i-1], the node vector of the interpolation curve is U, and the parameter is obtained by parameterization of the chord length.
The control vertex of the leaf spline curve is back-calculated by using a matrix, namely colPivHousehole der Qr (). solution (InterpolationVector) function in an Eigen3 library, wherein the matrix is an n + 1-dimensional square matrix, the InterpolationVector is an n + 1-dimensional vector of interpolation point coordinates, and the ControlVector is an n + 1-dimensional vector of control vertex coordinates.
Second order vector derivation calculation and reverse curvature determination
The basis functions are calculated as follows:
provision for
Ni，0(u) is 1, if ui≤u≤ui；Ni，kAnd (u) is 0, and other curve second derivative vector calculation is realized by adopting a method of derivation of a basis function, and the method comprises the following steps:
the method for determining the reverse curvature is shown in fig. 4, in which the reference point is the midpoint reference point between the first and last points of the curve, and is located away from the control vertex PiThe director at the point on the nearest curve is TiThe curvature vector is Vi, and the connection line between the control vertex and the reference point is VRiCalculating the vector product
Such as:
it means that there is no need to adjust the control vertex, if an abnormal situation occurs
It indicates that control vertex P is neededjAnd (6) adjusting. And for the control vertex which does not meet the control polygon convex protection, adding the control vertex index value related to the parameter value of the point into an abnormal interval table for subsequent adjustment. For example, for parameter value ui≤u＜ui+1，i∈[p，n]The position of the point is controlled by P +1 control vertexes Pi-p、Pi-p+1、……、PiCalculated to obtain [ i-p, i]And storing the abnormal interval table.
Adjusting the control vertex: and traversing the abnormal interval table, and adjusting the control vertex polygons in different forms in different adjusting modes under the condition that the control vertex polygons are not convex. To is directed atThe case where the control vertex section does not have sufficient adjustment capability (see fig. 3-a) is mainly divided into the case where only one control vertex is included (see fig. 3-b), the case where a plurality of control vertices to be adjusted are included (see fig. 3-c), and the 0 th control vertex P0In case of an adjustment interval, special handling is required (see fig. 3-d). Through the adjustment, the adjustment of the control polygon convex protection can be met, so that the condition that the spline curve meets the condition that the curvature vector points to the concave direction of the curve in the definition domain is ensured, and the curve fluctuation is eliminated.
Data saving and output: updating the position of the original control vertex replaced by the adjusted control vertex (see fig. 5, where the dotted line is the spline curve before adjustment and the solid line is the spline curve after adjustment), a new spline curve can be obtained. The stream output (str _ path, stream:: out) instruction outputs the control vertex and the node vector to the disk for saving. And calculating the minimum distance between the original interpolation point and the new spline curve as the adjustment error output of the curve, and storing, wherein the minimum distance between the point and the spline curve is calculated by adopting a SISL library function s1957 ().
The blade-type spline curve reverse curvature correction method and system for the turbine blade provided by the embodiment of the invention have the following advantages:
(1) in the conventional spline interpolation curve reverse curvature correction process, a designer often observes the curvature vector distribution condition of a section line and manually adjusts the position of an interpolation point.
(2) Compared with the traditional manual adjustment method, the method has the advantages that the manual labor is reduced, uncertain factors in the leaf-shaped spline curve modeling process are reduced, and the modeling stability and the modeling efficiency of the leaf-shaped spline curve are improved.
(3) The algorithm process is simple, the calculated amount is small, the requirement on machine configuration is small, and the method is easy to understand.
In another embodiment of the present invention, a system for modifying the inverse curvature of a spline curve of a bucket blade is provided for implementing the method of the preceding embodiments. Therefore, the description and definition in each embodiment of the aforementioned blade-type spline curve reverse curvature correction method for a turbine blade can be used for understanding each execution module in the embodiment of the present invention. Fig. 6 is a schematic diagram of the overall structure of a blade-shaped spline curve inverse curvature correction system for a turbine blade according to an embodiment of the present invention, which includes a first calculation module 61, a second calculation module 62, a determination module 63, an adjustment module 64, and a construction module 65.
The first calculating module 61 is configured to calculate and obtain a node vector and control vertex information of a leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade;
a second calculating module 62, configured to calculate a second derivative vector of the leaf-type spline curve at each interpolation point as a curvature vector;
a determining module 63, configured to determine a control vertex to be adjusted according to the curvature vector at each interpolation point;
an adjusting module 64, configured to adjust the position information of the control vertex to be adjusted according to the control vertex information;
and a constructing module 65, configured to construct an adjusted leaf spline curve based on the adjusted position information of the control vertex.
The blade-shaped spline curve reverse curvature correction system of the turbine blade provided by the embodiment of the invention corresponds to the blade-shaped spline curve reverse curvature correction method of the turbine blade provided by the foregoing embodiment, and the relevant technical features of the blade-shaped spline curve reverse curvature correction system of the turbine blade can refer to the relevant technical features of the blade-shaped spline curve reverse curvature correction method of the turbine blade, and are not described herein again.
Fig. 7 illustrates a physical structure diagram of an electronic device, and as shown in fig. 7, the electronic device may include: the system comprises a processor (processor)01, a communication Interface (Communications Interface)02, a memory (memory)03 and a communication bus 04, wherein the processor 01, the communication Interface 02 and the memory 03 complete mutual communication through the communication bus 04. Processor 01 may call logic instructions in memory 03 to perform the following method: calculating to obtain node vectors and control vertex information of the leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade; calculating a second derivative vector of the leaf spline curve at each interpolation point as a curvature vector; determining a control vertex needing to be adjusted according to the curvature vector at each interpolation point; adjusting the position information of the control vertex needing to be adjusted according to the control vertex information; and constructing an adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex.
In addition, the logic instructions in the memory 03 can be implemented in the form of software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The present embodiments provide a non-transitory computer-readable storage medium storing computer instructions that cause a computer to perform the methods provided by the above method embodiments, for example, including: calculating to obtain node vectors and control vertex information of the leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade; calculating a second derivative vector of the leaf spline curve at each interpolation point as a curvature vector; determining a control vertex needing to be adjusted according to the curvature vector at each interpolation point; adjusting the position information of the control vertex needing to be adjusted according to the control vertex information; and constructing an adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex.
Those of ordinary skill in the art will understand that: all or part of the steps for implementing the method embodiments may be implemented by hardware related to program instructions, and the program may be stored in a computer readable storage medium, and when executed, the program performs the steps including the method embodiments; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.
The above-described embodiments of the apparatus are merely illustrative, and the units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment. One of ordinary skill in the art can understand and implement it without inventive effort.
Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware. With this understanding in mind, the above-described technical solutions may be embodied in the form of a software product, which can be stored in a computer-readable storage medium such as ROM/RAM, magnetic disk, optical disk, etc., and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the embodiments or some parts of the embodiments.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A method for correcting the inverse curvature of a blade profile spline curve of a turbine blade, comprising:
calculating to obtain node vectors and control vertex information of the leaf-shaped spline curve according to interpolation point data of the leaf-shaped spline curve of the turbine blade;
calculating a second derivative vector of the leaf spline curve at each interpolation point as a curvature vector;
determining a control vertex needing to be adjusted according to the curvature vector at each interpolation point;
adjusting the position information of the control vertex needing to be adjusted according to the control vertex information;
and constructing an adjusted leaf-shaped spline curve based on the adjusted position information of the control vertex.
2. The method for modifying the inverse curvature of a blade-form spline curve of a turbine blade according to claim 1, wherein the calculating the nodal vectors and the control vertex information of the resulting blade-form spline curve from the interpolation point data of the blade-form spline curve of the turbine blade comprises:
calculating the parameter value of each interpolation point by adopting a preset parameterization method for the interpolation point data of the blade-shaped spline curve of the turbine blade;
calculating a node vector of the leaf spline curve according to the parameter value of each interpolation point;
and calculating to obtain the control node of the leaf-shaped spline curve according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline curve.
3. The method for blade-profile spline inverse curvature correction of a turbine blade of claim 2, wherein the preset parameterization methods include a uniform parameterization method, an accumulated chord length parameterization method, a centripetal parameterization method, and a Foley parameterization method.
4. The method for blade-spline reverse curvature correction of a turbine blade according to claim 3, wherein the calculating the parameter value of each interpolation point using a preset parameterization method for the interpolation point data of the blade-spline of the turbine blade comprises:
calculating the parameter value of each interpolation point by adopting a parameterization method of accumulated chord length:
wherein Q iskIs the coordinate of the kth interpolation point, | Qk-Qk-1L is the distance between the kth interpolation point and the (k-1) th interpolation point,
is the parameter value of the kth interpolation point.
5. The method of blade-spline reverse curvature correction for turbine blades according to claim 4, wherein said calculating a nodal vector of the blade-spline based on the parameter values for each interpolation point comprises:
u0＝…＝up＝0，um-p＝…＝um＝1，m＝n+p+1；
U＝[u0，u1，u2，……，un+p+1]，u∈[up，un+1]；
wherein m is the total number of node vectors of the leaf spline curve, n and p are positive integers,p is the number of B-spline basis functions, n is (interpolation point number +1),
is the parameter value of the ith interpolation point.
6. The method of claim 2, wherein the step of calculating the control nodes of the spline curve based on the parameter values of each interpolation point and the nodal vectors of the spline curve comprises:
and according to the parameter value of each interpolation point and the node vector of the leaf-shaped spline curve, calculating and obtaining a control node of the leaf-shaped spline curve by a matrix inversion method:
wherein the content of the first and second substances,
the parameter value for the kth interpolation point,
as a value of a parameter
P-th order B-spline basis function of (Q)kIs the coordinates of the kth interpolation point.
7. The method of blade-spline reverse curvature modification of a turbine blade according to claim 6, wherein the calculating a second derivative vector of the blade-spline curve at each interpolation point as a curvature vector comprises:
calculating a second derivative of each interpolation point of the leaf-shaped spline curve through the following formula, wherein the first derivative is a tangent vector of the leaf-shaped spline curve, and the second derivative is a curvature vector of the leaf-shaped spline curve:
Pi (0)＝Pi，k＝0；
C(k)(u)＝Ni，p-k(u)Pi (k)；
in the formula, C(k)(u) is the k-th derivative value at u as the parameter value of the interpolation point, when k is 2, C(2)(u)＝Ni，p-2(u)Pi (2)The parameter value for an interpolation point is the derivative value of order 2 at u, i.e. the curvature vector at that interpolation point.
8. The method for blade-spline reverse curvature modification of a turbine blade according to claim 1, wherein the determining a control vertex to be adjusted based on the curvature vector at each interpolation point comprises:
judging whether the curvature vector direction at each interpolation point is consistent with the theoretical direction;
recording the index value of an interpolation point with the curvature vector direction inconsistent with the theoretical direction, and acquiring the index value of a control vertex related to the index value of the corresponding interpolation point, wherein an index value interval formed by the index values of the control vertex is an abnormal interval, and the control vertex in the abnormal interval is a control vertex needing to be adjusted.
9. The method of leaf spline reverse curvature modification of a turbine blade of claim 8, wherein said adjusting the position information of the control vertices to be adjusted based on the control vertex information comprises:
for any abnormal interval, judging whether the curve segment of the leaf-shaped spline curve in any abnormal interval meets a convexity-keeping condition;
if the control vertex does not meet the requirement, the span of any abnormal interval needs to be expanded, and the position information of the control vertex in the abnormal interval after the span is expanded is adjusted;
and if so, adjusting the position information of the control vertex in any abnormal interval.
10. The method for blade-spline reverse curvature modification of a turbine blade according to claim 1, wherein the constructing the adjusted blade-spline curve based on the position information of the adjusted control vertex further comprises:
calculating the minimum distance between each interpolation point and the adjusted leaf-shaped spline curve, and judging whether each minimum distance is within an allowable value range;
and if not, adjusting the adjusted leaf-shaped spline curve again.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911144158.5A CN110908338B (en) | 2019-11-20 | 2019-11-20 | Blade profile spline reverse curvature correction method and system for turbine blade |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911144158.5A CN110908338B (en) | 2019-11-20 | 2019-11-20 | Blade profile spline reverse curvature correction method and system for turbine blade |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110908338A true CN110908338A (en) | 2020-03-24 |
| CN110908338B CN110908338B (en) | 2020-11-17 |
Family
ID=69818326
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911144158.5A Expired - Fee Related CN110908338B (en) | 2019-11-20 | 2019-11-20 | Blade profile spline reverse curvature correction method and system for turbine blade |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110908338B (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2739764B2 (en) * | 1989-12-15 | 1998-04-15 | 富士通株式会社 | Robot scanning speed control method |
| JPH10254526A (en) * | 1997-03-13 | 1998-09-25 | Toshiba Mach Co Ltd | Numerical controller |
| CN101201609A (en) * | 2007-12-04 | 2008-06-18 | 大连船舶重工集团有限公司 | Method for driving numerical control forming mill process watercraft sectional material component parts with inverse line mode |
| CN103344442A (en) * | 2013-07-26 | 2013-10-09 | 中国重汽集团济南动力有限公司 | Hybrid power system test bed and operating method thereof |
| CN103676786A (en) * | 2013-12-23 | 2014-03-26 | 北京航空航天大学 | Curve fairing method based on accelerated speed principle |
| CN105975759A (en) * | 2016-04-29 | 2016-09-28 | 山东科技大学 | L curve-based spectrum correction iteration method |
| CN108038259A (en) * | 2017-11-06 | 2018-05-15 | 中国商用飞机有限责任公司 | Method based on curvature generation Pneumatic component shape |
| CN108415367A (en) * | 2018-03-13 | 2018-08-17 | 南京航空航天大学 | A kind of automatic fiber placement track overall situation curvature Smoothing Algorithm |
-
2019
- 2019-11-20 CN CN201911144158.5A patent/CN110908338B/en not_active Expired - Fee Related
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2739764B2 (en) * | 1989-12-15 | 1998-04-15 | 富士通株式会社 | Robot scanning speed control method |
| JPH10254526A (en) * | 1997-03-13 | 1998-09-25 | Toshiba Mach Co Ltd | Numerical controller |
| CN101201609A (en) * | 2007-12-04 | 2008-06-18 | 大连船舶重工集团有限公司 | Method for driving numerical control forming mill process watercraft sectional material component parts with inverse line mode |
| CN103344442A (en) * | 2013-07-26 | 2013-10-09 | 中国重汽集团济南动力有限公司 | Hybrid power system test bed and operating method thereof |
| CN103676786A (en) * | 2013-12-23 | 2014-03-26 | 北京航空航天大学 | Curve fairing method based on accelerated speed principle |
| CN105975759A (en) * | 2016-04-29 | 2016-09-28 | 山东科技大学 | L curve-based spectrum correction iteration method |
| CN108038259A (en) * | 2017-11-06 | 2018-05-15 | 中国商用飞机有限责任公司 | Method based on curvature generation Pneumatic component shape |
| CN108415367A (en) * | 2018-03-13 | 2018-08-17 | 南京航空航天大学 | A kind of automatic fiber placement track overall situation curvature Smoothing Algorithm |
Non-Patent Citations (1)
| Title |
|---|
| 刘定焜: "《曲线曲面光顺的理论研究与实现》", 《中国优秀硕士学位论文全文数据库 信息科技辑》 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110908338B (en) | 2020-11-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN113505443B (en) | Self-adaptive Cartesian grid generation method for three-dimensional streaming problem with any shape | |
| Wang | A Quadtree-based adaptive Cartesian/Quad grid flow solver for Navier-Stokes equations | |
| JP5890105B2 (en) | Designing parts modeled by parallel geodesic lines | |
| JP2002070504A (en) | Blade shape designing method and information medium | |
| JP6708995B2 (en) | Blade design method and blade for axial flow fluid machine | |
| WO2021203711A1 (en) | Isogeometric analysis method employing geometric reconstruction model | |
| CN110689492B (en) | Image edge smoothing method and device | |
| CN110555214A (en) | compressor blade profile construction method and compressor blade | |
| CN108509718B (en) | Far-field wake two-dimensional analytic model based on mass conservation | |
| Ji et al. | Computer 3D vision-aided full-3D optimization of a centrifugal impeller | |
| CN110908338B (en) | Blade profile spline reverse curvature correction method and system for turbine blade | |
| CN111047684A (en) | Model simplification method based on three-dimensional model characteristics | |
| Shang et al. | Effective re-parameterization and GA based knot structure optimization for high quality T-spline surface fitting | |
| JP4981313B2 (en) | Three-dimensional shape processing apparatus, curved surface creation program, and curved surface creation method | |
| CN112967333B (en) | Complex point cloud skeleton extraction method and system based on grading | |
| CN111524236A (en) | Self-adaptive triangular network simplification method based on plane analysis | |
| CN117726710B (en) | Curve dispersion-based drawing method and related device | |
| Zhang et al. | A nonconforming surface mesh generation method by binary tree | |
| CN118097067B (en) | Triangular mesh model curved surface expansion method based on filtering processing | |
| CN117934764B (en) | Model simplifying method and system based on mesh model | |
| CN114419055B (en) | Developable surface segmentation-fitting method based on Gaussian image | |
| Harris et al. | Using the medial axis to represent flow features for feature-aligned unstructured quad-dominant mesh generation | |
| Lan et al. | Optimizing Mesh Simplification: A Newton-Based Approach to Quadratic Error Metrics | |
| CN113642130A (en) | Blade inner cavity design method, machine readable storage medium and data processing device | |
| Martínez Morera et al. | Subdivision curves on surfaces and applications |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20201117 Termination date: 20211120 |