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CN-122021048-A - Twisted rudder leading edge design method and system

CN122021048ACN 122021048 ACN122021048 ACN 122021048ACN-122021048-A

Abstract

The invention discloses a design method and a system for a twisted rudder leading edge, which are characterized in that flow field data of a propeller wake flow are obtained and subjected to multi-scale decomposition to identify a rotation direction leading region, a kinetic energy concentrating region and a shearing sensitive region in the wake flow, on the basis, a mapping relation between wake flow characteristic parameters and leading edge geometric parameters is established, a direction-spreading discrete distribution of leading edge target torsion angles and leading edge curvature parameters is generated, a leading edge torsion angle distribution function and a leading edge curvature distribution function which continuously change along the direction of rudder blade expansion are constructed in an interpolation mode, the leading edge is subjected to parametric description according to the distribution function, and the space torsion directions and the leading edge geometric forms of the leading edge are determined at different direction-spreading positions, so that the three-dimensional twisted rudder leading edge geometry is formed. According to the invention, the characteristics of the wake flow of the propeller are converted into the input variables of the guide edge design, so that the self-adaptive matching of the guide edge geometry to the wake flow structure is realized, the rudder front inflow condition is improved, the energy recovery effect is improved, and the unsteady load risk is reduced.

Inventors

  • CHEN BO
  • CHEN SIZHEN
  • CHU JIAJUN

Assignees

  • 江苏华帝海洋工程设备制造有限公司

Dates

Publication Date
20260512
Application Date
20260211

Claims (10)

  1. 1. The design method of the twisted rudder leading edge is characterized by comprising the following steps of: S1, under the self-propulsion working condition of a propeller, acquiring flow field data of a wake flow of the propeller at a preset reference surface, wherein the flow field data at least comprises an axial speed component, a circumferential speed component and time change information corresponding to the speed component; S2, carrying out multi-scale decomposition on the flow field data, identifying characteristic regions of the wake field, and carrying out parameterization expression on each characteristic region to form wake flow characteristic parameter sets, wherein the characteristic regions comprise a spiral direction leading region, a kinetic energy concentration region and a shearing sensitive region; S3, constructing a mapping relation between wake characteristic parameters and twisted rudder leading edge geometric parameters according to the wake characteristic parameter set, wherein the geometric parameters at least comprise leading edge torsion angle parameters and leading edge curvature parameters, so that the geometric parameters can be continuously changed along with the rudder blade expanding position; s4, generating a leading edge torsion angle distribution function and a leading edge curvature distribution function which continuously change along the rudder blade expanding direction according to the mapping relation, so as to determine the geometric states of the twisted rudder leading edge at different expanding positions; and S5, outputting the guide edge torsion angle distribution function and the guide edge front edge curvature distribution function as final design results, and constructing a three-dimensional geometric form of the twisted rudder guide edge so as to realize the matching design between the guide edge geometry and the propeller wake flow characteristics.
  2. 2. The twisted rudder leading edge design method according to claim 1, wherein the step S1 includes: providing a reference surface at a predetermined axial position downstream of the axis of the propeller Time sequence sampling is carried out on the propeller wake flow on the reference surface, and axial velocity components of the wake flow at different radial positions and circumferential positions are obtained Circumferential velocity component , wherein, Representing the position of said reference surface in the axial direction, r representing the radial coordinate with respect to the axis of the propeller, The circumferential angle coordinate is represented, and t represents the sampling time; in a complete propeller rotation period, carrying out time statistics on the axial speed component and the circumferential speed component, and respectively calculating the period average value of the axial speed component and the circumferential speed component, wherein the period average axial speed And a periodic average circumferential velocity The method meets the following conditions: Wherein T 0 is the starting time of period statistics, and T p is the rotation period of the propeller; Calculating the pulsation intensity of the axial velocity of the wake flow based on the fluctuation condition of the axial velocity component in a propeller rotation period It satisfies the following conditions: Wherein, the A preset positive number for avoiding zero denominator; Thereby at the reference plane Wake flow field data is formed that includes both periodic average axial velocity, periodic average circumferential velocity, and axial velocity pulse intensity.
  3. 3. The twisted rudder leading edge design method according to claim 2, wherein the identifying of the turning dominant region in step S2 includes: Let rudder blade spanwise height be H r , reference plane The spanwise coordinate in the rudder blade projection range is marked as z, and the spanwise normalized coordinate is defined as , Is the lower boundary coordinate of the rudder blade spanwise range, is positioned on the reference plane On which discrete sampling point sets are established , The radial sampling coordinates are represented as such, Representing the circumferential sampling angle coordinate, and mapping each sampling point to the normalized spanwise coordinate corresponding to the rudder blade spanwise coordinate z Thereby establishing a one-to-one correspondence between the reference surface sampling points and the rudder blade spanwise positions; for any unfolding position Selecting a sampling point set corresponding to the spanwise location on the reference surface And calculates the periodic average circumferential velocity in the sampling point set The spanwise statistical mean of (a): Wherein, the Representing a set of sampling points Each sampling point in the inner part carries out arithmetic average; According to the statistical mean value of the spanwise direction Is to determine the spin direction attribute when When the spanwise position is determined to be a forward rotation region The reverse rotation area is determined, and the rotation strength threshold coefficient is introduced to avoid the symbol noise interference of weak rotation area When (when) And determining the spanwise layer as a spiral dominant layer, The maximum value of the amplitude of the average circumferential speed of the global period of the reference plane; And merging all the spanwise position sets which simultaneously meet the spanwise direction judging condition and the spanwise strength threshold condition, defining the spanwise position sets as a spanwise dominant region, and determining the upper and lower boundary intervals of the spanwise dominant region in the rudder blade spanwise direction through the minimum spanwise coordinates and the maximum spanwise coordinates corresponding to the sets.
  4. 4. A twisted rudder leading edge design method according to claim 3, wherein the identifying of the kinetic energy concentration area in step S2 includes: for the radial position on the reference plane, for the periodic average circumferential velocity Statistical averaging is carried out along the circumferential angle direction, and radial circumferential kinetic energy density characteristic quantities are defined as follows: Wherein, the Representing a full circumferential arithmetic average at a fixed radial coordinate r; for the radial normalized coordinates, Is the radius of the propeller; for the radial circumferential kinetic energy density characteristic quantity in the whole radial position range Comparing and determining the maximum value Introducing a proportional threshold coefficient When (when) And when the radial section is judged to be a kinetic energy concentrated radial zone, all radial positions meeting the condition are concentrated to form radial continuous or discrete kinetic energy concentrated sections, and the corresponding area of the radial section on the reference surface is defined as a kinetic energy concentrated area for representing the main distribution position of recoverable circumferential kinetic energy in the wake of the propeller.
  5. 5. The twisted rudder leading edge design method according to claim 4, wherein the identifying of the shear sensitive area in step S2 includes: First, a shear/surge sensitivity index is constructed: Wherein, the A pulsation intensity representing an axial velocity on the reference surface; Representing the periodic average axial velocity; representing two-dimensional gradient operators defined in a reference plane, ; Under the discrete sampling condition, the radial partial derivative of the periodic average axial speed is approximately calculated by adopting a central difference mode: The circumferential partial derivative of the periodic average axial speed is approximately calculated by adopting an angular center difference mode: Wherein, the Representing the i-th radial sampling point coordinate, Represents the jth circumferential sampling angle; Based on the radial partial derivative and Zhou Xiangpian derivative, calculating the periodic average axial velocity gradient modulus in the reference plane as follows: and thus obtain the shear/fluctuation sensitivity index corresponding to each sampling point of the reference surface ; Analyzing the statistical distribution of the shear/surge sensitivity index in the whole sampling point range of the reference surface, and correspondingly obtaining all sampling points Sorting the values, selecting the statistical value Q q with quantiles Q, and when a certain sampling point meets the following conditions And collecting all sampling points meeting the condition on a reference plane and defining the sampling points as a shearing sensitive area for representing an area which is more sensitive to control surface pressure pulsation, local cavitation and vibration response under the combined action of speed pulsation and speed gradient in the wake of the propeller.
  6. 6. The twisted rudder leading edge design method according to claim 5, wherein the step S3 includes: Rudder blade spanwise normalized coordinates As independent variable, constructing the leading edge torsion angle parameter Is used for the spread-direction continuous mapping relation, The rudder blade spanwise coordinate corresponding to the mth spanwise discrete layer, In order to make the torsion direction of the leading edge consistent with the direction attribute of the spiral direction leading area, the guiding edge is positioned at each spreading position Where the sign function of the direction of rotation is introduced , wherein, Is a sign function and is used for representing positive and negative attributes of the numerical value; to be spread to the position Statistical mean of spanwise direction of periodic average circumferential velocity when Indicating a positive twist when The time indicates reverse twist; after determining the torsion direction, the guide edge torsion angle amplitude is designed to be determined by the rotation strength characteristic quantity Kinetic energy covering characteristic quantity Risk suppression feature quantity The common driving, constructing the spanwise continuous mapping relation of the torsion angle of the edge guiding target is as follows: Wherein, the To be spread to the position The torsion angle of the edge guiding target at the position, The exponential parameters p, q and s are non-negative real numbers and are used for adjusting the sensitivity degree of the rotation direction intensity characteristic quantity, the kinetic energy coverage characteristic quantity and the risk suppression characteristic quantity to the guide edge torsion angle; As a truncated function, when Get a when B is taken when the time is, otherwise x is taken; through the mapping relation, the steering angle of the steering wheel is continuously changed in the direction of the rudder blade, the torsion effect is enhanced in the area with dominant steering direction and concentrated kinetic energy, and the torsion amplitude is restrained in the area with higher shearing or pulsation risk, so that the torsion distribution of the steering wheel is obtained, wherein the torsion distribution is matched with the structural characteristics of the wake flow of the propeller.
  7. 7. The twisted rudder leading edge design method according to claim 6, wherein the step S3 includes: firstly, constructing a non-uniformity degree index of inflow in the direction of the exhibition: Wherein, the A global maximum value which is a modulus value of a periodic average axial velocity gradient in a reference plane; an extremely small positive number for preventing the denominator from being zero; On the basis, the target distribution of the leading edge curvature is designed to be determined by the inflow non-uniformity index And risk suppression feature quantity Commonly adjusted and employing leading edge radius of curvature As an intermediate variable, the spanwise continuous mapping relationship of the leading edge curvature radius is defined as: Wherein w 1 、w 2 is a non-negative weight coefficient used to characterize the relative contribution of inflow non-uniformity and shear sensitivity to leading edge passivation requirements; representing the range of allowable leading edge radii of curvature; According to the radius of curvature of the leading edge Determining leading edge curvature parameters as ; The curvature parameter of the leading edge is continuously changed in the direction of the rudder blade, the passivation degree of the leading edge is automatically increased in the area with strong inflow gradient or high shearing/pulsation risk, and the curvature change is kept small in the non-sensitive area, so that the geometric distribution of the leading edge matched with the wake structure of the propeller and the local pressure distribution characteristic is obtained.
  8. 8. The twisted rudder leading edge design method according to claim 7, wherein the step S4 includes: In the spread discrete sequence for obtaining the torsion angle of the edge guiding target Spread-wise discrete sequence of leading edge radii of curvature Then, N z is the total number of spanwise discrete layers, and the discrete sequence is converted into a leading edge torsion angle distribution function and a leading edge curvature distribution function which continuously change along the spanwise direction of the rudder blade, and the process includes: Opposite edge twist angle distribution function Leading edge radius of curvature distribution function Interpolation construction is carried out by adopting a segmented cubic Hermite interpolation function, and the interpolation construction is carried out between each adjacent spanwise node interval Respectively to inside And (3) with Constructing a piecewise cubic polynomial to enable the function value to be continuous and the first derivative to be continuous; in any adjacent node interval In, define normalized interval parameters Definition of Hermite basis functions as Accordingly, the leading edge twist angle distribution function within the interval is expressed as: Wherein, the 、 A guide edge torsion angle discrete value at the adjacent direction-expanding node; And (3) with Respectively nodes And (3) with A first derivative of the lead edge torsion angle with respect to the spanwise coordinate; In the same manner, a discrete sequence of leading edge radii of curvature of the guide edge Constructing a spanwise continuous radius of curvature distribution function And further by A leading edge curvature distribution function is determined, Representing the geometric curvature of the leading edge at the corresponding spanwise location.
  9. 9. The twisted rudder leading edge design method according to claim 8, wherein step S5 includes: In obtaining a leading edge torsion angle distribution function continuously changing along the rudder blade expanding direction Radius of curvature distribution function of leading edge And then, generating a space description for constructing the three-dimensional twisted rudder leading edge geometry in a parameterization mode: first, defining the guiding datum line in the state of not applying torsion The reference line is used for representing the spatial position of the guide edge in the direction of the rudder blade in the untwisted state, and is parameterized and expressed as , wherein, , The reference projection curve of the rudder blade shape at the leading edge is used for determining; Subsequently, in either deployed position In the local cross-section plane, a leading edge local coordinate system is established, and the normal unit vector is defined as The tangential unit vector is defined as , Is consistent with the chord direction of the rudder blade section and And (3) with Orthogonal in the cross-sectional plane; with said leading edge twist angle distribution function Characterizing the rotation angle of the local direction of the leading edge relative to the reference direction, applying a twisted unit vector of the leading edge direction Expressed as On the basis, the leading edge curvature radius distribution function is utilized Defining the geometric circular arc shape of the leading edge in the partial section, wherein the curvature of the leading edge meets the following condition The curvature is used for controlling the passivation degree of the front edge at the corresponding spreading position, and the leading edge is approximately expressed as radius in the partial section Determining the circle center position and the circle arc end point according to the geometric continuity condition of the circle arc and the rest part of the rudder blade section, thereby obtaining the front edge geometry of the guide edge section at the spreading position; By positioning each of the display positions Direction vector of warp direction Determining direction and radius of curvature of leading edge And determining the leading edge curves of the leading edge sections in the local arc shapes, and connecting the leading edge curves along the direction of the spanwise direction of the rudder blade to form continuous three-dimensional twisted rudder leading edge curved surfaces, so that the leading edge space geometric states matched with wake flow characteristics are determined at different spanwise positions.
  10. 10. A twisted rudder leading edge design system based on the method of any one of claims 1 to 9, characterized in that the system comprises the following modules: The flow field data acquisition and management module is used for acquiring or importing propeller wake flow field data under a self-propulsion working condition, wherein the flow field data at least comprises an axial speed component, a circumferential speed component and related data representing unsteady pulsation intensity on a reference surface, and uniformly managing the flow field data with different sources or different sampling densities so as to ensure that subsequent processing is carried out under the definition of consistent space reference and coordinates; The data preprocessing and unifying module is used for preprocessing the flow field data and comprises the steps of denoising and outlier removing the sampled data, interpolating and unifying or resampling a space sampling grid, phase aligning a time sequence and carrying out reference system correction on a speed component, so that an axial speed component and a circumferential speed component are expressed under the same coordinate system, and a wake flow data set with alignable time and space is formed; The multi-scale decomposition and characteristic region identification module is used for respectively carrying out radial scale decomposition, spanwise scale decomposition and time scale decomposition on the wake flow data after the unification treatment, identifying the axial inflow non-uniformity degree and the circumferential kinetic energy distribution characteristics through radial statistics, identifying a wake flow swirling dominant region and the boundary thereof through spanwise statistics, and identifying a shearing sensitive region through the coupling of pulsation intensity and speed gradient, thereby obtaining a swirling dominant region, a kinetic energy concentration region and a shearing sensitive region; the wake characteristic parameter set construction module is used for parametrizing the rotation direction leading region, the kinetic energy concentration region and the shearing sensitive region to form a wake characteristic parameter set which can be indexed according to the spreading position and is used as input for generating guide edge geometric parameters; The geometric parameter mapping generation module is used for establishing a mapping relation between wake characteristic parameters and guide geometric parameters based on the wake characteristic parameter set, generating a spanwise discrete distribution of guide target torsion angles and a spanwise discrete distribution of guide front edge curvature or front edge curvature radius, and applying an allowable range constraint to the torsion angle amplitude; The spreading direction serialization and manufacturability guarantee module is used for converting the spreading direction discrete distribution of the guide edge target torsion angle and the front edge curvature or the front edge curvature radius into function expression continuously changing along the spreading direction of the rudder blade so as to ensure the continuity and smoothness of the guide edge geometric parameter in the spreading direction and avoid abrupt change of the geometric parameter; And the three-dimensional guide edge geometry generating module is used for constructing a guide edge datum line based on the continuous guide edge torsion angle distribution function and the front edge curvature or front edge curvature radius distribution function, determining the space torsion direction and the front edge geometry of the guide edge at each spreading position, and connecting the guide edge sections at each spreading position along the spreading direction so as to generate a continuous three-dimensional torsion rudder guide edge geometry model.

Description

Twisted rudder leading edge design method and system Technical Field The invention belongs to the field of ship propulsion system design, and particularly relates to a twisted rudder leading edge design method and system. Background In a ship propulsion system, a propeller and a rudder are usually relatively close in space position, a wake field with obvious rotation characteristics and strong non-uniformity is formed behind the propeller when the propeller works, the rudder blade is in the wake action area for a long time, and the hydrodynamic characteristics born by the rudder blade are obviously different from those under open water conditions. The propeller wake exhibits not only a significant radial gradient in the axial velocity profile, but also a strong rotation-induced velocity in the circumferential direction, accompanied by complex turbulent pulsations and shear structures. The complex wake environment has important influence on the lift force characteristic, the resistance characteristic, the rudder shaft load, the cavitation and vibration performance of the rudder, and is one of key factors for restricting the further improvement of the propulsion efficiency and the maneuvering performance. In order to improve the disadvantageous interference between propeller and rudder and to recover the rotational energy in the wake of the propeller, rudder designs with twisted leading edges are increasingly occurring in the prior art. The scheme generally changes the geometric form of the rudder blade leading edge to enable the rudder blade leading edge to be attached to the rotating direction of the propeller wake flow to a certain extent, so that the rectification wake flow is realized, the energy loss is reduced, and the propulsion efficiency is improved. However, the existing design method of the twisted guide quarter rudder mostly depends on engineering experience or a small amount of parameterization, for example, adopting sinusoidal, folded line type or curve type guiding edges, and comparing and screening different schemes through numerical calculation or model test. Although the method has a certain effect in practical engineering application, the design thought of the method is still basically remained at the level of presetting geometric forms and then performing performance verification. Because the propeller wake has obvious spatial non-uniformity and time fluctuation characteristics, the flow structure of the propeller wake continuously changes along with the rotation of the blade, and the propeller wake shows differences in different radial positions, different spanwise heights and different working conditions, and the actual characteristics of the wake field are difficult to accurately reflect by the existing twisted edge guiding design method based on the fixed geometric type. Especially under the multi-working condition operation condition, the model selection is simply carried out by means of single or few edge guiding forms, limited improvement can be obtained only under specific working conditions, and the problems of extra resistance, increase of rudder shaft torque or cavitation risk increase and the like can be introduced under other working conditions. In addition, in the twisted guide edge design process in the prior art, the wake flow of the propeller is usually taken as a result object of performance evaluation, namely, the influence of the wake flow on rudder performance is observed through calculation or experiment, and the wake flow field is less analyzed and utilized as a systematic design basis. The axial speed distribution, the circumferential rotation characteristic and the turbulence pulsation information contained in the wake flow cannot be effectively extracted and converted into parameters capable of guiding the geometrical design of the rudder blade leading edge, so that the determination of the leading edge torsion angle, the change rule and the action range lacks uniform theoretical basis, and the design process has stronger experience and trial-and-error property. Under the background, how to more fully know the space and time characteristics of the propeller wake flow and avoid conducting edge guiding selection only by experience or limited parameters, so that effective matching between the twisted edge guiding geometry and the actual wake flow characteristics is realized, and the technical problem to be solved in the existing marine twisted rudder design technology is urgent. Disclosure of Invention In order to solve the technical problems, the invention provides a design method and a system for a twisted rudder leading edge. Specifically, the technical scheme provided by the invention is as follows: a design method of a twisted rudder leading edge comprises the following steps: S1, under the self-propulsion working condition of a propeller, acquiring flow field data of a wake flow of the propeller at a preset reference surface, wherein the flow field data at lea