A fully parameterized design method for high-skew propellers

Abstract

The present invention provides a fully parameterized large skew propeller design method, which specifically includes the following steps: S1: determining the characteristic parameters of the airfoil section, namely, the chord length, the maximum camber, the maximum thickness, the leading edge radius and the trailing edge radius; and determining the corresponding trim, skew and pitch of the airfoil section under different radial directions; S2: using three-dimensional modeling software, establishing the airfoil section model of the large skew propeller airfoil under different radial directions; S3: obtaining the original parameter curve according to the chord length, the maximum camber, the maximum thickness, trim, skew and pitch corresponding to the airfoil section model under different radial directions; performing curve fitting on each original parameter curve to obtain the corresponding fitting parameter curve, and obtaining the large skew propeller airfoil surface model by the integration method; and connecting the large skew propeller airfoil surface model with the constructed hub model to form a closed large skew propeller model. The present invention solves the problem that it is difficult to achieve flexible control of the geometric shape of the large skew propeller in the prior art.

Description

Technical Field

[0001] The present invention relates to the field of ship propulsion technology, and in particular to a fully parameterized large-skew propeller design method. Background Art

[0002] The currently proposed methods for propeller modeling usually require manual establishment of a three-dimensional solid propeller model. For example, Zhang Hongwei et al. proposed a program design method for calculating propeller type value point coordinates, and manually imported the data file through ProE software for solid modeling, but did not study the rapid modeling method after the type value points were imported into the software; Wu Lihong et al. used MATLAB to calculate the spatial coordinate points of the propeller blades, and read the spatial coordinate points into ProE at one time, but needed to manually establish a three-dimensional solid propeller; Liu Kanle et al. used PropCAD and Rhino software to study the rapid method of propellers, but ultimately still needed to manually complete the establishment of the propeller three-dimensional model.

[0003] The manual method of building a three-dimensional model is difficult to achieve flexible control of the geometric shape of the large skew propeller. It is impossible to change the solid model by changing the characteristic parameters, and it is impossible to establish the relationship between the geometric characteristics of the large skew propeller and the performance of the large skew propeller. Summary of the invention

[0004] In view of the technical problems existing in the existing propeller modeling methods, a fully parameterized large skew propeller design method is provided. By establishing a fully parameterized large skew propeller model, the large skew propeller model can be flexibly controlled when studying the relationship between the geometric characteristics of the large skew propeller and the performance of the large skew propeller, which meets sufficient optimization design sample space, ensures the high efficiency of the performance prediction and optimization of the large skew propeller, and improves the large skew propeller performance optimization system.

[0005] The technical means adopted by the present invention are as follows:

[0006] A fully parameterized high-skew propeller design method specifically comprises the following steps:

[0007] S1: Determine the camber distribution line and thickness distribution line of the airfoil section at different radial directions according to the large skew propeller airfoil, determine the characteristic parameters of the airfoil section, and simultaneously determine the longitudinal inclination, skew and pitch corresponding to the airfoil section at different radial directions;

[0008] The characteristic parameters of the airfoil section include chord length, maximum camber, maximum thickness, leading edge radius and trailing edge radius;

[0009] S2: Use 3D modeling software to build the airfoil section model of the large side-skew propeller airfoil at different radial directions

[0010] According to the camber distribution line, thickness distribution line and characteristic parameters determined in step S1, a characteristic parameter description method is used to establish an airfoil section model of the large skew propeller airfoil at different radial directions;

[0011] S3: Use 3D modeling software to build a large side-skew propeller model

[0012] According to the chord length, maximum camber, maximum thickness, trim, skew and pitch corresponding to the airfoil section model under different radial directions, the original parameter curves are obtained: maximum chord length curve, maximum thickness curve, maximum camber curve, pitch curve, trim curve and skew curve;

[0013] According to the F-spline curve fitting principle, each original parameter curve is fitted to obtain the corresponding fitting parameter curve. In the curve fitting process, the variance of the fitting points between the final fitting parameter curve and the original parameter curve is guaranteed to be the smallest. According to the fitting parameter curve, the large skew propeller airfoil surface model is obtained by the integration method.

[0014] In the 3D modeling software, the airfoil surface model of the large skew propeller is connected with the constructed hub model through Boolean operation to form a closed large skew propeller model.

[0015] Furthermore, the large skew propeller model includes several large skew propeller airfoil surface models, and other large skew propeller airfoil surface models are obtained by copying and rotating a large skew propeller airfoil surface model in three-dimensional modeling software.

[0016] Furthermore, the 3D modeling software used is CAESES.

[0017] Furthermore, step S4 is also included: parametric control of the large skew propeller model is achieved by adjusting the chord length, maximum camber, maximum thickness, leading edge radius, trailing edge radius, longitudinal tilt, skew and pitch corresponding to the airfoil section model of the large skew propeller airfoil at different radial directions in the three-dimensional modeling software.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The fully parametric large skew propeller design method provided by the present invention establishes a large skew propeller by means of fully parametric modeling, can realize flexible control of the geometric model of the large skew propeller, converts the geometric information of the solid model into characteristic parameters, and can realize accurate expression of the solid model by defining the characteristic parameters; by changing the characteristic parameters, the solid model can be changed, so that the performance of the large skew propeller can be optimized; and the parametric modeling of the large skew propeller can better establish the relationship between the geometric characteristics of the large skew propeller and the performance of the large skew propeller.

[0020] Based on the above reasons, the present invention can be widely promoted in the field of ship propulsion. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 It is a schematic diagram of the airfoil section of the large side-skew propeller of the present invention.

[0023] Figure 2 It is a schematic diagram of the longitudinal inclination, lateral inclination and pitch of the present invention.

[0024] Figure 3 It is the mapping relationship between the airfoil parameter curve and the high skew propeller model in the fully parameterized high skew propeller design method of the present invention.

[0025] Figure 4 The figure is a schematic flow chart of the fully parameterized large skew propeller design method of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] like Figure 1-4 As shown, the wing section is the most important part in the design of a large skew propeller, and the airfoil performance determines the overall performance of the large skew propeller; and the wing section shape directly affects the hydrodynamic performance of the wing section, so it is necessary to adopt a suitable wing section parameterization method to express the continuous and smooth wing section geometric shape; the method provided by the present invention can achieve accurate expression of the entity model by defining characteristic parameters; the present invention provides a fully parameterized large skew propeller design method, which specifically includes the following steps:

[0029] S1: Determine the camber distribution line and thickness distribution line of the airfoil section at different radial directions according to the large skew propeller airfoil, determine the characteristic parameters of the airfoil section, and simultaneously determine the longitudinal inclination, skew and pitch corresponding to the airfoil section at different radial directions;

[0030] The characteristic parameters of the airfoil section include chord length, maximum camber, maximum thickness, leading edge radius, and trailing edge radius.

[0031] like Figure 1 As shown in the figure, the front point on the airfoil section is called the leading edge point, and the last point is called the trailing edge point. The distance between the leading edge point and the trailing edge point is the chord length. The flow velocity on the upper surface of the airfoil is faster (suction surface), and the flow velocity on the lower surface is slower (pressure surface). The trailing edge tip is taken as the center of the circle, and a circle is made from the trailing edge to the leading edge, which is tangent to the pressure surface and the suction surface. The centers of all circles are connected to form the camber distribution line of the airfoil section. The maximum value of the distance from the center line to the inner chord is called the maximum camber. The maximum distance between the suction surface and the pressure surface is the maximum thickness. Different leading edge and trailing edge shapes will cause different changes to the performance of the airfoil, and it is necessary to ensure that the thickness of the trailing edge meets the design requirements. Therefore, setting the leading edge radius and the trailing edge radius as characteristic parameters to control the shapes of the leading edge and the trailing edge can make the change of the airfoil shape more flexible.

[0032] like Figure 2 As shown, a straight line formed by connecting the center points of the chord lines of the airfoil section at different radial directions when there is no skew and trim is used as a blade reference line; a straight line formed by connecting the center points of the chord lines of the airfoil section at different radial directions of the large skew propeller airfoil adopted in this application is used as a propeller reference line; the longitudinal distance between the blade reference line and the propeller reference line is called the trim (rake); the angle formed by the blade reference line and the propeller reference line in the front view direction is called the skew (skew); take an airfoil section, extend the chord line of the airfoil section, and circle the axis for one circle. The axial distance between the two end points A and B of the spiral line formed is the pitch (pitch) of the airfoil section of the propeller airfoil at this radial direction;

[0033] S2: Use 3D modeling software to build the airfoil section model of the large side-skew propeller airfoil at different radial directions

[0034] According to the camber distribution line, thickness distribution line and characteristic parameters determined in step S1, a characteristic parameter description method is used to establish an airfoil section model of the large skew propeller airfoil at different radial directions;

[0035] S3: Use 3D modeling software to build a large side-skew propeller model

[0036] According to the chord length, maximum camber, maximum thickness, trim, skew and pitch corresponding to the airfoil section model under different radial directions, the original parameter curves are obtained: maximum chord length curve, maximum thickness curve, maximum camber curve, pitch curve, trim curve and skew curve;

[0037] The chord length curve, maximum thickness curve and maximum camber curve can express the shape of the large skew propeller airfoil, and the pitch curve, skew curve and pitch curve can express the distribution of the large skew propeller airfoil in the circumferential, axial and radial directions.

[0038] According to the F-spline curve fitting principle, each original parameter curve is fitted to obtain the corresponding fitting parameter curve. In the curve fitting process, the variance of the fitting points between the final fitting parameter curve and the original parameter curve is guaranteed to be the smallest. According to the fitting parameter curve, the large skew propeller airfoil surface model is obtained by the integration method.

[0039] The present invention uses fewer control variables to accurately fit the curve and the idea of ​​minimizing the variance of the fitting points, which greatly reduces the error between the fitting parameter curve and the original parameter curve; the F-Spline curve is used to express the characteristic parameters of the propeller blade parameters, which can clearly express the distribution of the propeller chord length, thickness, camber, pitch, side tilt, and pitch parameters, and at the same time, a smoother distribution curve is generated after changing the parameters. The surface model generated in this way can maintain good smoothness;

[0040] In the 3D modeling software, the airfoil surface model of the large skew propeller is connected with the constructed hub model through Boolean operation to form a closed large skew propeller model.

[0041] Furthermore, the large skew propeller model includes several large skew propeller airfoil surface models, and other large skew propeller airfoil surface models are obtained by copying and rotating a large skew propeller airfoil surface model in three-dimensional modeling software.

[0042] Furthermore, the 3D modeling software used is CAESES.

[0043] Furthermore, step S4 is also included: parametric control of the large skew propeller model is achieved by adjusting the chord length, maximum camber, maximum thickness, leading edge radius, trailing edge radius, longitudinal inclination, skew and pitch corresponding to the airfoil section model of the large skew propeller airfoil at different radial directions in the three-dimensional modeling software. Specifically, by changing various parameters, the airfoil shape can be changed, thereby achieving parametric control of the large skew propeller model.

[0044] Furthermore, the F-spline curve fitting specifically includes the following steps:

[0045] S31: for a certain original parameter curve, select the first and last two points as reference points of the fitting curve, the first point represents the starting point of the first F-spline curve, and the last point represents the end point of the second F-spline curve;

[0046] S32: intercepting n fitting points from the head point to the tail point on the original parameter curve to fit the original parameter curve, each intercepted point can be used as the end point of the first F-spline curve and the starting point of the second F-spline curve, and the two F-spline curves corresponding to each point are fitted into an intermediate fitting curve, and finally n intermediate fitting curves are obtained;

[0047] S33: Calculate the variance of n fitting points intercepted from each intermediate fitting curve and n fitting points intercepted from the original parameter curve, and take the intermediate fitting curve with the smallest variance as the final fitting parameter curve. The variance calculation formula is as follows:

[0048] s 2 =[(x1-x) 2 +...(x n -x) 2 ] / n

[0049] Among them, s 2 represents the variance, x1....x n Represents the value of each fitting point, x represents x1....x n The average value of , n represents the number of fitting points.

[0050] Furthermore, step S32 extracts 50 fitting points from the original parameter curve from the head point to the tail point for curve fitting.

[0051] The present invention can express the geometric characteristics of a large skew propeller in a parameterized manner. When studying the relationship between the geometric parameters of a large skew propeller and the performance of a large skew propeller, the method provided by the present invention can be used. By defining characteristic parameters, the precise expression of the entity model can be achieved; by changing the characteristic parameters, the entity model can be changed, and the parametric modeling of the large skew propeller can be achieved, and a sufficient sample space for optimization calculation can be established. The flexibility of parameterized control ensures the high efficiency of performance prediction and optimization of the large skew propeller, and improves the performance optimization system of the large skew propeller.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fully parameterized high-skew propeller design method, characterized in that: The specific steps include: S1: Determine the camber distribution line and thickness distribution line of the airfoil section at different radial directions according to the large skew propeller airfoil, determine the characteristic parameters of the airfoil section, and simultaneously determine the longitudinal inclination, skew and pitch corresponding to the airfoil section at different radial directions; The characteristic parameters of the airfoil section include chord length, maximum camber, maximum thickness, leading edge radius and trailing edge radius; S2: Use 3D modeling software to build the airfoil section model of the large side-skew propeller airfoil at different radial directions According to the camber distribution line, thickness distribution line and characteristic parameters determined in step S1, a characteristic parameter description method is used to establish an airfoil section model of the large skew propeller airfoil at different radial directions; S3: Use 3D modeling software to build a large side-skew propeller model According to the chord length, maximum camber, maximum thickness, trim, skew and pitch corresponding to the airfoil section model under different radial directions, the original parameter curves are obtained: maximum chord length curve, maximum thickness curve, maximum camber curve, pitch curve, trim curve and skew curve; According to the F-spline curve fitting principle, each original parameter curve is fitted to obtain the corresponding fitting parameter curve. In the curve fitting process, the variance of the fitting points between the final fitting parameter curve and the original parameter curve is guaranteed to be the smallest. According to the fitting parameter curve, the large skew propeller airfoil surface model is obtained by the integration method. In the 3D modeling software, the airfoil surface model of the large skew propeller is connected with the constructed hub model through Boolean operation to form a closed large skew propeller model.

2. The fully parameterized high-skew propeller design method according to claim 1, characterized in that: The large skew propeller model includes several large skew propeller airfoil surface models, and other large skew propeller airfoil surface models are obtained by copying and rotating a large skew propeller airfoil surface model in three-dimensional modeling software.

3. The fully parameterized high-skew propeller design method according to claim 1, characterized in that: The 3D modeling software used is CAESES.

4. The fully parameterized high-skew propeller design method according to claim 1, characterized in that: The method also includes step S4: parameterizing the large skew propeller model by adjusting the chord length, maximum camber, maximum thickness, leading edge radius, trailing edge radius, longitudinal inclination, skew and pitch corresponding to the airfoil section model of the large skew propeller airfoil at different radial directions in the three-dimensional modeling software.

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