Three-dimensional modeling method and system for annular propeller

Abstract

The invention relates to the technical field of ship propulsion, and discloses a three-dimensional modeling method and system for an annular propeller, and the method comprises the steps: obtaining geometric basic parameters of the annular propeller, building a rotating coordinate system based on pitch change, and defining a reference line of the annular propeller; acquiring profile value parameters and control angle information of the annular propeller along the pitch direction, wherein all the parameters are continuously distributed according to sections in the pitch direction. And based on the reference line and the control angle of the annular propeller, mapping the profile parameter to a three-dimensional space under a cylindrical coordinate system, sequentially calculating three-dimensional coordinate points of the blade section at each pitch position, controlling the camber angle, the roll angle and the vertical angle of each pitch point, and completing position transformation and attitude adjustment of the blade section. And performing fairing connection on the three-dimensional coordinate points of the blade sections at all the pitches by adopting a B spline curve, fitting the profile contour, constructing a continuous blade surface, and generating a three-dimensional geometric model of the annular propeller. The method lays a foundation for follow-up development of physical characteristics and scientific problems of the annular propeller.

Description

Technical Field

[0001] This invention relates to the field of ship propulsion technology, specifically to a three-dimensional modeling method and system for annular propellers. Background Technology

[0002] Since Archimedes first designed the propeller around 200 BC, humans have relied on this high-speed rotating device with radial blades for propulsion in the air or water for centuries. However, traditional propellers still have some unresolved drawbacks, reaching a bottleneck in improving propulsion efficiency and reducing hydrodynamic noise. The introduction of the toroidal propeller has brought new ideas because it has the potential to improve propulsion efficiency and reduce vibration and noise. In recent years, it has received widespread attention. Currently, research has begun abroad and it is being applied in the marine field. In 2013, Sharrow Marine applied for a patent for a toroidal propeller and developed a marine propulsion device. They claimed that the propulsion device could improve propulsion efficiency and reduce noise in underwater propulsion. In 2017, MIT updated and applied for a patent for a toroidal propeller, which was approved in 2020. However, in China, research on toroidal propellers is still in its infancy.

[0003] A reliable modeling method is a prerequisite for conducting scientific research on toroidal propellers. However, the geometry of toroidal propellers is complex, and currently, a mathematical expression for the geometry of toroidal propellers and its modeling methods have not yet been established, which limits their research and development. Summary of the Invention

[0004] Therefore, the technical problem solved by this invention is that a reliable modeling method is a prerequisite for conducting scientific research on annular propellers. However, the geometry of annular propellers is complex, and currently, a mathematical expression for the geometry of annular propellers and its modeling methods have not been established, which limits their research and development.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a three-dimensional modeling method for annular propellers, comprising: obtaining the basic geometric parameters of the annular propeller, determining the structural composition of the blade entry section, tip section and discharge section according to the axial direction of the total pitch, establishing a rotating coordinate system based on pitch variation and defining the annular propeller reference line.

[0006] The form parameters and control angle information of the annular propeller are obtained along the pitch direction. The form parameters include chord length, pitch ratio, maximum thickness, maximum camber, pitch and skew. The control angle information includes outboard angle, roll angle and vertical angle. All parameters are continuously distributed in segments along the pitch direction.

[0007] Based on the annular propeller reference line and control angle, the model parameters are mapped to a three-dimensional space in cylindrical coordinates. The three-dimensional coordinate points of the blade profile at each pitch position are calculated sequentially. The outward tilt angle, side tilt angle, and vertical angle of each pitch point are controlled to complete the position transformation and attitude adjustment of the blade profile.

[0008] B-spline curves were used to smoothly connect the three-dimensional coordinate points of the blade profile at all pitches, fit the profile contour, and construct a continuous blade surface to generate a three-dimensional geometric model of the annular propeller.

[0009] As a preferred embodiment of the three-dimensional modeling method for the annular propeller described in this invention, the acquisition of the geometric basic parameters of the annular propeller includes: collecting the total pitch, diameter, radius, hub-to-diameter ratio, and number of blades of the annular propeller; dividing the blades into three parts: the entry section, the tip section, and the discharge section; determining the pitch axial path from the root to the tail of the blades; and defining the curve formed by the change of radius with distance in the pitch direction as a reference line in the rotating coordinate system when the annular propeller is rotating in place.

[0010] In a preferred embodiment of the three-dimensional modeling method for the annular propeller described in this invention, the reference line comprises: a two-dimensional function curve based on pitch variation constructed in a rotating coordinate system. The curve is defined between the pitch axial direction and the local radius of the blade, forming a differentiable continuous path that controls the position mapping of the blade profile in cylindrical coordinates. The center point of the blade profile at any pitch position coincides with the corresponding point on the reference line.

[0011] As a preferred embodiment of the three-dimensional modeling method for annular propellers described in this invention, the step of obtaining the shape parameters and control angle information of the annular propeller along the pitch direction includes: setting the local radius, chord length, pitch ratio, maximum thickness, and maximum camber of the blade profile at each pitch position, and setting the pitch and skew values ​​respectively. A thickness distribution function and a camber distribution function are constructed based on the read shape points, and recorded as the correspondence between pitch position and parameters.

[0012] As a preferred embodiment of the three-dimensional modeling method for annular propellers described in this invention, the outward inclination angle includes: defining the angle between the radial line at each pitch position in the radial direction and the reference line as the outward inclination angle, setting it to a negative value in the entry section, setting it to a positive value in the discharge section, and continuously varying it as a transition region in the tip section, thereby achieving precise control of the offset angle between the entry section and the discharge section on the entire blade structure. The outward inclination angle is a pitch control input and participates in determining the projection position of the cross-section in the cylindrical coordinate system.

[0013] As a preferred embodiment of the three-dimensional modeling method for annular propellers described in this invention, the side tilt angle includes: the side tilt angle is the angle between the tangent of the blade reference line at the pitch of the blade section and the radial straight line. By adjusting the rotation state of the section in the thickness direction, the side tilt angle changes continuously along the pitch direction, so that the section thickness is adapted to the total longitudinal tilt change.

[0014] In a preferred embodiment of the three-dimensional modeling method for the annular propeller described in this invention, the vertical angle includes: the vertical angle being the angle between the chord of the profile and the tangent of rotation, reflecting the offset direction of the incoming angle of attack; the vertical angle adopts a segmented continuous distribution strategy in the pitch direction, with the tip segment set as the peak value, and the inlet and outlet segments decreasing to zero values ​​sequentially. The vertical angle adjusts the rotation state of each pitch profile around the tangent of rotation, constituting a geometric adjustment input for adaptability to the angle of attack.

[0015] As a preferred embodiment of the three-dimensional modeling method for the annular propeller described in this invention, the step of sequentially calculating the three-dimensional coordinate points of the blade profile at each pitch position includes: at each pitch position, projecting the radius, chord length, camber, and thickness functions onto the cylindrical coordinate system, and combining the outward tilt angle, side tilt angle, and vertical angle at the current pitch point, performing three rotation transformations to obtain the final coordinate expression of the profile point in three-dimensional space. The three sets of angles respectively control the translation, normal deflection, and angle of attack attitude of the blade profile.

[0016] As a preferred embodiment of the three-dimensional modeling method for the annular propeller described in this invention, the method for generating the three-dimensional geometric model of the annular propeller includes: constructing the blade envelope boundary by B-spline interpolation based on the coordinates of the center points of the cross-sections at all pitches, constructing the blade mesh using the cross-section point set, establishing a smooth spatial transition surface through parametric expression, and outputting a visualized three-dimensional structural model of the annular propeller.

[0017] A three-dimensional modeling system for a ring-shaped propeller, characterized in that it includes:

[0018] The parameter acquisition and segmentation module acquires the basic geometric parameters of the annular propeller, determines the structural composition of the blade entry section, tip section, and discharge section based on the axial direction of the total pitch, establishes a rotating coordinate system based on pitch variation, and defines the annular propeller reference line.

[0019] The model value extraction and database construction module obtains the model value parameters and control angle information of the annular propeller along the pitch direction. The model value parameters include chord length, pitch ratio, maximum thickness, maximum camber, pitch and skew, and the control angle information includes outboard angle, roll angle and vertical angle. All parameters are continuously distributed in segments along the pitch direction.

[0020] The profile coordinate mapping module, based on the annular propeller reference line and control angle, maps the model parameters to a three-dimensional space in cylindrical coordinate system, calculates the three-dimensional coordinate points of the blade profile at each pitch position in sequence, controls the outward tilt angle, side tilt angle and vertical angle of each pitch point, and completes the position transformation and attitude adjustment of the blade profile.

[0021] The spline fitting modeling module uses B-spline curves to smoothly connect the three-dimensional coordinate points of the blade profile at all pitches, fits the profile contour, constructs a continuous blade surface, and generates a three-dimensional geometric model of the annular propeller.

[0022] The beneficial effects of this invention are as follows: Because the blade of a ring propeller is a closed structure with a complex geometry, the radial distribution of geometric parameters in traditional propellers is no longer applicable. Currently, no scholar has proposed a mathematical expression method for it. This invention establishes a mathematical expression method for the geometry of a ring propeller, using a distribution of geometric parameters along the pitch. It also requires the introduction of three geometric parameters—outer tilt angle, side tilt angle, and vertical angle—to fully express its geometric shape. Based on the method established in this invention, by inputting geometric parameters, the coordinate points on each pitch blade section of the ring propeller can be quickly calculated, thereby establishing a smooth three-dimensional geometric model of the ring propeller. This enables rapid three-dimensional modeling of the ring propeller, laying a solid foundation for subsequent research on the physical characteristics and scientific problems of ring propellers. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0024] Figure 1 The first embodiment of the present invention provides an overall flowchart of a three-dimensional modeling method and system for a ring propeller.

[0025] Figure 2 A schematic diagram of a ring propeller, which is provided in the first embodiment of the present invention, for a three-dimensional modeling method and system of a ring propeller.

[0026] Figure 3 This is a schematic diagram illustrating the coordinate system definition of the annular propeller of the present invention, which is a three-dimensional modeling method and system for annular propellers provided in the first embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram illustrating the change in the reference line of the annular propeller before and after the outboard angle, provided as a first embodiment of the present invention, which is a three-dimensional modeling method and system for annular propellers.

[0028] Figure 5 This is a schematic diagram of the thickness of the propeller blade before and after rotation, provided as the first embodiment of the present invention, which is a three-dimensional modeling method and system for annular propellers.

[0029] Figure 6 The first embodiment of the present invention provides a three-dimensional modeling method and system for annular propellers, and the vertical angle diagram of the annular propeller of the present invention is shown.

[0030] Figure 7 This is a schematic diagram showing the coordinate points and model correspondence of a three-dimensional modeling method and system for a ring propeller provided in the first embodiment of the present invention. Detailed Implementation

[0031] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0032] Example 1, referring to Figures 1-6 As an embodiment of the present invention, a three-dimensional modeling method for a ring-shaped propeller is provided, comprising:

[0033] Determine the geometric parameters of the annular propeller, including the annular propeller diameter, hub-to-diameter ratio, and number of blades. The annular propeller consists of blades and a hub. Each blade is a closed annular structure, including an inlet section, a tip section, and an outlet section.

[0034] Introducing the concept of pitch, the shape parameters of traditional propellers vary radially, i.e., they are functions related to the radius. This method is not applicable to the closed blades of annular propellers. In order to accurately express the geometric shape of annular propellers, this invention introduces the concept of pitch, defining the axial distance between the root of the inlet section and the root of the outlet section as the total pitch L (span). Pitch refers to the axial distance l between the midpoint of the chord line of each blade section and the root of the inlet section, excluding the total longitudinal tilt. The geometric parameters of the annular propeller are distributed along the pitch direction.

[0035] Define a reference line for the annular propeller. Assume that the annular propeller rotates in place and the rotating coordinate system fixed on the annular propeller is (x, r, θ). Define the curve formed by the radius changing along the pitch when θ = 0 on the plane as the reference line of the annular propeller. The reference line of the annular propeller can be expressed by formula (1).

[0036]

[0037] Where x represents the position variable along the axial direction (pitch direction). r represents the radius of the blade profile in cylindrical coordinates (radial position). θ represents the rotation angle coordinate in cylindrical coordinates. l represents the pitch variable, indicating the distance position of the blade profile along the axial direction. l (l) represents the radius function value corresponding to the pitch l. The radial profile of the annular propeller reference line is defined as θ = 0, which represents the initial angle of the reference line (the plane is set as θ = 0).

[0038] Determine the model parameters of the annular propeller, including the radius, chord length, pitch ratio, maximum thickness, maximum camber, longitudinal tilt, and sideslip of the annular propeller along the pitch direction, as well as the thickness and camber distribution of the blade profile along the chord length direction.

[0039] Introducing the camber angle, the angle between the radial line of the pitch in the projection profile and the annular propeller reference line is defined as the camber angle. The angle between the entry and exit sections of the annular propeller blades is increased or decreased by controlling the outward tilt angle along the pitch direction. There is a certain interval between the entry and exit sections of the blades, and the exit section is located in the wake of the entry section. In order to achieve the best propulsion efficiency matching, the outward tilt angle should be reasonably selected. Under normal circumstances, the outward tilt angles of the entry and exit sections of the annular propeller are opposite. After introducing the outward tilt angle, combined with the distribution of the blade profile around the blade reference line, the mathematical expression of the three-dimensional coordinates of the annular propeller in the cylindrical coordinate system o-xrθ can be initially obtained as formula (2).

[0040]

[0041] Where, x T y represents the relative axial offset distance of the blade profile in the rotating coordinate system. b represents the total chord length of the profile. s represents the axial distribution variable of points within the profile relative to the profile centerline. β represents the outward inclination angle, defined as the angle between the radial line at the pitch position and the tangent to the reference line. b This represents the offset value of the lower boundary point in the profile thickness distribution function. f This represents the offset value of the upper boundary point in the profile thickness distribution function.

[0042] Introducing the roll angle and using formula (2) to represent the geometry of the annular propeller presents a problem: the total longitudinal roll variation at the blade tip is very large, which leads to the thickness distribution of the tip section being different from the actual blade profile. Formula (2) alone cannot fully and accurately express the geometry of the annular propeller. In order to ensure that each blade profile of the annular propeller can accurately reflect the actual thickness distribution, the roll angle ψ is introduced here. The geometric meaning of the roll angle is the angle between the tangent of the blade reference line at the location of the blade profile and the radial straight line, that is, the rotation angle of the blade profile from the horizontal position to the position perpendicular to the blade reference line. After introducing the roll angle, the blade profile at each pitch can more realistically reflect the thickness distribution of the blade. In the cylindrical coordinate system o-xrθ, after adding the roll angle to the blade profile at each pitch l, the three-dimensional coordinate mathematical expression formula in formula (2) becomes the following formula (3).

[0043]

[0044] Where ψ represents the tilt angle, which is the angle by which the profile is rotated about the normal direction of its location, used to restore the true thickness direction. cosψ and sinψ represent the adjustment components of the vertical rotation angle of the profile.

[0045] Introducing a vertical angle, the angle of attack of the blade profile is only affected by the pitch when there is no roll angle. However, the introduction of the roll angle will bring a problem, namely, the incoming flow of the blade profile at each pitch l on the blade will change. In order to better adjust the incoming flow angle of the annular propeller blade profile and adapt it to the working environment, a vertical angle α is introduced here. The geometric meaning of the vertical angle is the angle between the chord of the blade profile and the rotation tangent. By adjusting the vertical angle, the blade profile can be lifted or pulled down relative to the rotation tangent. Setting a vertical angle at the tip section can make the fluid suck into the interior of the blade "ring", but it will also increase the rotational resistance. In addition, the vertical angle at the tip section can also make the fluid generate a flow that deviates from the direction of advance. Therefore, the vertical angle of the blade needs to be rotated reasonably. In the cylindrical coordinate system o-xrθ, after adding a vertical angle to the blade profile at each pitch l, the three-dimensional coordinate mathematical expression formula in equation (3) becomes the following equation (4).

[0046]

[0047] Where α represents the vertical angle, which is the angle between the chord of the section and the tangent of rotation. cosα and sinα represent the projection adjustment of the vertical angle in the spatial direction, used to correct the angle of attack of the section.

[0048] The three-dimensional coordinates of the annular propeller are determined by the above steps. After introducing the pitch, outward tilt, side tilt and vertical angle of the annular propeller, the three-dimensional coordinate points on the blade section at each pitch l in the cylindrical coordinate system o-xrθ are mathematically expressed as formula (5), and the three-dimensional coordinates of the annular propeller at each pitch l in the rectangular coordinate system o-xyz are expressed as formula (6).

[0049]

[0050] Where y = rcosθ represents the transformation from cylindrical coordinates to rectangular coordinates, and z = rsinθ represents the transformation from cylindrical coordinates to rectangular coordinates.

[0051] The three-dimensional model of the annular propeller is determined. Based on the geometric values ​​of the annular propeller in the above steps, the smooth geometric shape curve of the annular propeller is expressed by the B-spline curve parameters, and the three-dimensional coordinates of the annular propeller are obtained, thus generating the three-dimensional model of the annular propeller.

[0052] Example 2, refer to Figure 7 As an embodiment of the present invention, a three-dimensional modeling method and system for a ring propeller is provided. To verify the beneficial effects of the present invention, a simulation experiment is conducted for scientific demonstration.

[0053] A program was developed in FORTRAN to generate a 3D model of a toroidal propeller. Given the geometric features of the toroidal propeller (diameter, hub-to-diameter ratio, number of blades and radius, chord length, pitch, thickness, trim, skew angle, outboard angle, vertical angle, blade profile distribution along the pitch), the program obtains the 3D coordinates of the blade profile at each pitch by running the program. These coordinates can then be imported into 3D software to fit a 3D model of the toroidal propeller. The specific implementation process of the method proposed in this invention is as follows:

[0054] The geometric parameters of the annular propeller were determined, including an overall pitch of 160 mm, a diameter of 800 mm, a hub-to-diameter ratio of 0.2, a number of blades of 3, and a blade profile type of NACA66-mod.

[0055] To determine the reference line of the annular propeller, assume that the annular propeller rotates in place and the rotating coordinate system fixed on the annular propeller is (x, r, θ). Define the curve formed by the radius changing along the pitch when θ = 0 on the plane as the reference line of the annular propeller. The blade profile of the annular propeller is distributed along the reference line.

[0056] Determine the model parameters of the annular propeller, including the radius, chord length, pitch ratio, maximum thickness, maximum camber, longitudinal tilt, and sideslip of the annular propeller along the pitch direction, as well as the thickness and camber distribution of the blade profile along the chord length direction.

[0057] The outboard angle is determined by controlling its magnitude along the pitch direction to increase or decrease the offset angle between the entry and exit sections of the annular propeller blades. There is a certain interval between the entry and exit sections, with the exit section located in the wake of the entry section. To achieve optimal propulsion efficiency, the outboard angle must be appropriately selected. The outboard angles of the entry and exit sections of the annular propeller are opposite; that is, the outboard angle of the entry section is negative, and the outboard angle of the exit section is positive. The tip section is the transitional region between the positive and negative outboard angle values.

[0058] The roll angle is determined geometrically as the angle between the tangent to the blade reference line at the location of the blade profile and the radial line. It represents the rotation angle of the blade profile from a horizontal position to a position perpendicular to the blade reference line. By introducing blade profiles at each radius, a specific rotation angle can be freely selected, ensuring that the blade tip thickness is approximately equal to the blade profile thickness. Simultaneously, to ensure blade smoothness, the roll angle varies continuously between the entry, tip, and exit sections, ranging from 0° to 180°. The change in roll angle should correspond to the change in overall pitch. In the entry and exit sections, since the overall pitch change is small, the roll angle change does not need to be large. However, in the tip section, the overall pitch change is larger, and the roll angle change should be larger. In this example, the roll angle increases slowly from 0° to 20° in the entry section, rapidly from 20° to 160° in the tip section, and slowly from 160° to 180° in the exit section.

[0059] Determining the vertical angle, geometrically defined as the angle between the chord line of the blade profile and the tangent of rotation, allows for the reasonable adjustment of the incoming angle of attack of the annular propeller blade profile. By adjusting the vertical angle, the blade profile can be raised or lowered relative to the tangent of rotation. Setting a vertical angle at the tip section allows fluid to be drawn into the interior of the blade "ring," but this also increases rotational resistance. Furthermore, a vertical angle at the tip section can cause the fluid to flow away from the direction of propulsion. Therefore, the vertical angle of the blade must be rotated appropriately. There are typically three distribution patterns of the vertical angle across the pitch: 1) The vertical angle of all blade profiles is set to zero. 2) The vertical angles of the inlet and tip sections are positive, while the vertical angle of the outlet section is negative. 3) The vertical angles of all blade profiles are positive, but the vertical angles of the inlet and tip sections should be greater than those of the outlet section. In this example, the peak vertical angle is at the tip, decreasing rapidly from the tip to the root of the inlet and outlet sections.

[0060] The three-dimensional coordinates of the propeller are determined. The geometric values ​​of the annular propeller determined by the above steps are processed by B-spline curve parameterization to obtain the smooth geometric shape curve of the annular propeller. The three-dimensional coordinate points of the upper blade section of each pitch of the annular propeller are obtained by the three-dimensional coordinate formulas (7) and (8).

[0061]

[0062] To obtain a three-dimensional model of the propeller, import the obtained three-dimensional coordinate points of the annular propeller into 3D software. Figure 7 .

[0063] Example 3, an embodiment of the present invention, provides a three-dimensional modeling system for a ring-shaped propeller, comprising:

[0064] The parameter acquisition and segmentation module acquires the basic geometric parameters of the annular propeller, determines the structural composition of the blade entry section, tip section, and discharge section based on the axial direction of the total pitch, establishes a rotating coordinate system based on pitch variation, and defines the annular propeller reference line.

[0065] The model value extraction and database construction module obtains the model value parameters and control angle information of the annular propeller along the pitch direction. The model value parameters include chord length, pitch ratio, maximum thickness, maximum camber, pitch and skew, and the control angle information includes outboard angle, roll angle and vertical angle. All parameters are continuously distributed in segments along the pitch direction.

[0066] The profile coordinate mapping module, based on the annular propeller reference line and control angle, maps the model parameters to a three-dimensional space in cylindrical coordinate system, calculates the three-dimensional coordinate points of the blade profile at each pitch position in sequence, controls the outward tilt angle, side tilt angle and vertical angle of each pitch point, and completes the position transformation and attitude adjustment of the blade profile.

[0067] The spline fitting modeling module uses B-spline curves to smoothly connect the three-dimensional coordinate points of the blade profile at all pitches, fits the profile contour, constructs a continuous blade surface, and generates a three-dimensional geometric model of the annular propeller.

[0068] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0069] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0070] More specific examples (a non-exhaustive list) of computer-readable media include: electrical connections (electronic devices) having one or more wires, portable computer disk drives (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Furthermore, computer-readable media can even be paper or other suitable media on which programs can be printed, because programs can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in computer memory.

[0071] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc. It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0072] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A three-dimensional modeling method for a ring-shaped propeller, characterized in that, include: Obtain the basic geometric parameters of the annular propeller, determine the structural composition of the blade entry section, tip section and discharge section according to the axial direction of the total pitch, establish a rotating coordinate system based on pitch variation and define the annular propeller reference line; The form parameters and control angle information of the annular propeller are obtained along the pitch direction. The form parameters include chord length, pitch ratio, maximum thickness, maximum camber, pitch and skew. The control angle information includes outboard angle, roll angle and vertical angle. All parameters are continuously distributed in segments along the pitch direction. Based on the annular propeller reference line and control angle, the model parameters are mapped to a three-dimensional space in cylindrical coordinate system. The three-dimensional coordinate points of the blade profile at each pitch position are calculated sequentially. The outward tilt angle, side tilt angle and vertical angle of each pitch point are controlled to complete the position transformation and attitude adjustment of the blade profile. B-spline curves were used to smoothly connect the three-dimensional coordinate points of the blade profile at all pitches, fit the profile contour, and construct a continuous blade surface to generate a three-dimensional geometric model of the annular propeller.

2. The three-dimensional modeling method for annular propellers as described in claim 1, characterized in that: The process of obtaining the geometrical fundamental parameters of the annular propeller includes: Collect the total pitch, diameter, radius, hub-to-diameter ratio, and number of blades of the annular propeller. Divide the blades into three parts: the entry section, the tip section, and the discharge section. Determine the pitch axial path from the root to the tail of the blades. When the annular propeller is rotating in place, define the curve formed by the change of radius with distance in the pitch direction as the reference line in the rotating coordinate system.

3. The three-dimensional modeling method for annular propellers as described in claim 2, characterized in that: The reference line includes: A reference line is constructed in the rotating coordinate system, which is a two-dimensional function curve based on pitch variation. The curve is defined between the pitch axial direction and the local radius of the blade, forming a differentiable continuous path to control the position mapping of the blade profile in the cylindrical coordinate system. The center point of the blade profile at any pitch position coincides with the corresponding point on the reference line.

4. The three-dimensional modeling method for annular propellers as described in claim 3, characterized in that: The acquisition of the annular propeller's shape parameters and control angle information along the pitch direction includes: Set the local radius, chord length, pitch ratio, maximum thickness and maximum camber of the blade profile at each pitch position, and set the longitudinal tilt and skew values ​​respectively; Based on the reading values, a thickness distribution function and an camber distribution function are constructed and recorded as the correspondence between pitch position and parameters.

5. The three-dimensional modeling method for annular propellers as described in claim 4, characterized in that: The outward tilt angle includes: The angle between the radial line at each pitch position in the radial direction and the reference line is defined as the outward inclination angle. It is set to a negative value in the entry section, a positive value in the exit section, and continuously varies in the tip section as a transition area. This achieves precise control of the offset angle between the entry and exit sections throughout the entire blade structure. The outward inclination angle is the pitch control input and participates in determining the projection position of the profile in the cylindrical coordinate system.

6. The three-dimensional modeling method for annular propellers as described in claim 5, characterized in that: The roll angle includes: The side tilt angle is the angle between the tangent of the blade reference line at the pitch of the blade profile and the radial straight line. By adjusting the rotation of the profile in the thickness direction, the side tilt angle changes continuously along the pitch direction, so that the profile thickness is adapted to the total longitudinal tilt change.

7. The three-dimensional modeling method for annular propellers as described in claim 6, characterized in that: The vertical angle includes: The vertical angle is the angle between the chord of the profile and the tangent of the rotation, reflecting the offset direction of the incoming angle of attack. The vertical angle adopts a segmented continuous distribution strategy in the pitch direction, with the tip segment set as the peak value, and the inlet and outlet segments decreasing to zero value in turn. The vertical angle adjusts the rotation state of each pitch profile around the tangent of the rotation, forming a geometric adjustment input for adaptability to the angle of attack.

8. The three-dimensional modeling method for annular propellers as described in claim 7, characterized in that: The step of sequentially calculating the three-dimensional coordinates of the leaf profile at each pitch position includes: At each pitch position, the radius, chord length, camber, and thickness functions are projected onto the cylindrical coordinate system. Combined with the outward tilt, side tilt, and vertical angle at the current pitch point, three rotation transformations are performed to obtain the final coordinate expression of the profile point in three-dimensional space. The three sets of angles control the translation, normal deflection, and angle of attack attitude of the blade profile, respectively.

9. The three-dimensional modeling method for annular propellers as described in claim 8, characterized in that: The three-dimensional geometric model for generating the annular propeller includes: Based on the coordinates of the center points of the profiles at all pitches, the leaf envelope boundary is constructed by B-spline interpolation, the leaf surface mesh is constructed using the profile point set, and the spatial smooth transition surface is established through parametric expression, outputting a visualized three-dimensional structural model of the annular propeller.

10. A three-dimensional modeling system for a ring-shaped propeller, characterized in that: The parameter acquisition and segmentation module acquires the basic geometric parameters of the annular propeller, determines the structural composition of the blade entry section, tip section and discharge section based on the axial direction of the total pitch, establishes a rotating coordinate system based on pitch variation and defines the annular propeller reference line. The model value extraction and database construction module obtains the model value parameters and control angle information of the annular propeller along the pitch direction. The model value parameters include chord length, pitch ratio, maximum thickness, maximum camber, pitch and skew, and the control angle information includes outboard angle, side angle and vertical angle. All parameters are continuously distributed in segments along the pitch direction. The profile coordinate mapping module, based on the annular propeller reference line and control angle, maps the model parameters to a three-dimensional space in cylindrical coordinate system, calculates the three-dimensional coordinate points of the blade profile at each pitch position in sequence, controls the outward tilt angle, side tilt angle and vertical angle of each pitch point, and completes the position transformation and attitude adjustment of the blade profile. The spline fitting modeling module uses B-spline curves to smoothly connect the three-dimensional coordinate points of the blade profile at all pitches, fits the profile contour, constructs a continuous blade surface, and generates a three-dimensional geometric model of the annular propeller.

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