CN104834774A - Comprehensive optimization design method and design platform for stratospheric composite material propeller - Google Patents

Abstract

The invention provides a comprehensive optimization design method and a design platform for a stratospheric composite material propeller, and aims to research composite material propeller designs, including an aerodynamic shape design and a structural design under the conditions of high altitude and low Reynolds number. The aerodynamic design of the propeller comprises an airfoil profile design and a propeller type design; the structural design refers to a lay-up design of a composite material; the requirement of fluid-solid coupling is considered actively in aerodynamic and structural optimization, so that aerodynamic-structural comprehensive integral design is realized. The method comprises the selection of design variables, the calculation of aerodynamic/structural performance and the implementation of an optimization process, so that a good design effect is achieved, and good reference is provided for the determination of a next-step fine design scheme.

Description

A kind of stratosphere composite propeller Synthetical Optimization method and design platform

Technical field

The present invention relates to stratosphere Design of Propeller technical field, be specially a kind of stratosphere composite propeller Synthetical Optimization method and the design platform of considering fluid structurecoupling.

Background technology

The design of stratosphere screw propeller relates to multiple subjects that pneumatic, structure etc. exists coupling, and high performance design proposal requires the requirement initiatively considering fluid structurecoupling in pneumatic and structure optimization, realizes pneumatic, structure composition integrated design.There is the features such as optimized variable is many, analytical work amount is large, exchanges data is complicated in such complex optimization problem.At present, considering both at home and abroad the screw propeller Optimization Design also imperfection of solid-fluid coupling deformation impact, is all study the elastic deformation of fixed wing and pneumatic, Optimal Structure Designing substantially.Therefore, propose Synthetical Optimization method, and be necessary based on this stratosphere composite propeller Synthetical Optimization platform building consideration fluid structurecoupling.First be the problem how a large amount of pneumatic, structural design variable are chosen, the existing design for stratosphere screw propeller does not also have the method for clear and definite minimizing design variable, increases difficulty to optimizing process; Next is that optimizing process relates to multiple subject, and interdisciplinary exchanges data also has problems, and organizes and implements and has certain difficulty, in the urgent need to a kind of complete optimization system coordinating to be coupled between every subjects.

Existing document has carried out Primary Study for the optimization design problem of stratosphere composite propeller at present, but all mainly for simple pneumatic design or structural design, is not effectively combined by these two subjects and carry out comprehensive Design.Want the comprehensive Design of really effectively carrying out stratosphere screw propeller, current problem demanding prompt solution has: one is On The Choice that is pneumatic, Structure Optimization Variables; Two is the data problem of transmission in fluid and structural simulation module; Three is integration problems of pneumatic, structural calculation module and fluid and structural simulation module; Four is select suitable optimization method and optimisation strategy.

Summary of the invention

In order to overcome the situation that the pneumatic design that exists in existing method for designing and structural design isolate mutually, the present invention proposes a kind of stratosphere composite propeller Synthetical Optimization method considering fluid structurecoupling.

Technical scheme of the present invention is:

A kind of described stratosphere composite propeller Synthetical Optimization method, is characterized in that: comprise the following steps:

Step 1: choose design variable:

Pneumatic design variable is the propeller pitch angle of the radial location residing for propeller blade maximum chord length, propeller blade maximum chord length, screw propeller blade root place chord length, screw propeller blade tip place chord length, screw propeller blade root place propeller pitch angle, screw propeller blade tip place propeller pitch angle, propeller blade maximum chord length present position;

Structural design variable is: the laying distance of the laying number of plies of laying group number, each laying group, the laying angle of each laying group, each laying group, the material of each laying group;

Step 2: use Latin hypercube experimental design method value in the span of design variable, obtain some samples;

Step 3: for each group sample point, the pneumatic design variable extracted wherein carries out Pneumatic Calculation, and the structural design variable extracted wherein carries out Structure Calculation, and consider the impact of fluid structurecoupling in Structure Calculation:

Step 3.1: control section by 12 and propeller blade is divided into 11 regions along exhibition to direction; According to 7 pneumatic design variablees and propeller blade chord length, propeller pitch angle along blade exhibition to the regularity of distribution in direction, obtain chord length and propeller pitch angle that 12 control section, and adopt the mode of Quadric spline curve matching to obtain the aerodynamic configuration of propeller blade between adjacent control section, set up the aerodynamic model of propeller blade, and enter step 3.2 with this aerodynamic model;

Step 3.2: based on the propeller blade aerodynamic model entering this step, by solving the averaged Navier-Stokes equation under absolute coordinate system based on the fully implicit solution dual time method introducing Multigrid Technique and exercise testing technology that contain the sub-iteration of newton-type, numerical simulation screw propeller axial flow Viscous Flow, obtains the pneumatic distributed force of screw propeller under axial flow state, pulling force, power, torque and efficiency;

Step 3.3: based on propeller blade aerodynamic model and four groups of structural design variablees, obtained the structural model of propeller blade by parametric modeling;

Step 3.4: the pneumatic distributed force of step 3.2 gained is transformed on the grid of the structural model of step 3.3 gained, then carries out structure finite element calculating, obtain the stress of propeller blade, strain, frequency, displacement and weight;

Step 3.5: structural model grid displacement step 3.4 obtained is transformed on aerodynamic model surface mesh, obtain new aerodynamic model surface mesh, and judge whether to meet the condition of convergence, if do not meet the condition of convergence, return step 3.2 with the new aerodynamic model surface mesh obtained, if meet the condition of convergence, end step 3, obtain the response that this group sample point is corresponding, described response is the Pneumatic Calculation result meeting the condition of convergence: the pneumatic distributed force of screw propeller under axial flow state, pulling force, power, torque and efficiency, and meet the Structure Calculation result of the condition of convergence: the stress of propeller blade, strain, frequency, displacement and weight,

Step 4: it is complete whether some samples that determining step 2 obtains all calculate, if do not calculate complete, returns and performs step 3, otherwise set up sample set with some samples that step 2 obtains, and enter step 5 with this sample set;

Step 5: according to entering the response structure agent model that in the sample set of this step and sample set, sample is corresponding, and enter step 6 with this agent model;

Step 6: based on the agent model entering this step, adopts genetic algorithm to be optimized:

Step 6.1: initial population scale and maximum evolutionary generation are set, and optimization object function and the constraint condition of setting up pneumatic and Structure Calculation; Described optimization aim is: pneumatic efficiency is the highest, weight is the lightest, frequency is the highest; Described constraint condition is: pneumatic restraint condition: power is not more than the peak power output of screw propeller drive motor, and torque is not more than the torque capacity that screw propeller drive motor can provide; Structure constraint: stress, strain meet the requirement of laminated material own;

Step 6.2: adopt mixing floating-point encoding method to encode to pneumatic design variable, adopt the method for integer coding to encode to structural design variable, the coding mapping of pneumatic design variable and structural design variable is become a gene string;

Step 6.3: set up fitness function according to the optimization object function of step 6.1 and constraint condition; The initial population that random generation is made up of N number of gene string, and enter step 6.4 with initial population;

Step 6.4: using adaptability function is assessed the population entering this step, obtains the highest C of a fitness value gene string; Crossover and mutation operation is carried out to C the gene string obtained, obtains population of new generation;

Step 6.5: judge whether to reach maximum evolutionary generation, if do not reach maximum evolutionary generation, then return step 6.4 with population of new generation, carry out another generation evolution, if reach maximum evolutionary generation, then the maximum adaptation degree gene string obtained in evolutionary process is decoded, obtain optimum sample;

Step 7: adopt the Pneumatic Calculation of step 3 and structure computation method to obtain the response of optimum sample; Calculate the response of the optimum sample that this suboptimization obtains and the last difference optimizing the response of the optimum sample obtained, and judge whether the difference ratio of the response of optimum sample that suboptimization obtains therewith is not more than 1%, if, then export optimum sample and response thereof that this suboptimization obtains or lastly optimize the optimum sample and response thereof that obtain, otherwise, the optimum sample this suboptimization obtained adds sample set, obtains new sample set; Step 5 is returned with new sample set.

Further preferred version, a kind of described stratosphere composite propeller Synthetical Optimization method, is characterized in that: the span of pneumatic design variable is the radial location residing for propeller blade maximum chord length: 50%R ~ 80%R; Propeller blade maximum chord length: 0.1R ~ 0.2R; Screw propeller blade root place chord length: 0.05R ~ 0.2R; Screw propeller blade tip place chord length: 0.02R ~ 0.1R; Screw propeller blade root place propeller pitch angle: 25 ° ~ 45 °; Screw propeller blade tip place propeller pitch angle: 5 ° ~ 10 °; The propeller pitch angle of propeller blade maximum chord length present position: 10 ° ~ 15 °; R is propeller blade radius.

Further preferred version, a kind of described stratosphere composite propeller Synthetical Optimization method, it is characterized in that: in step 3.5, the condition of convergence is: the propeller blade displacement calculated according to this structure finite element, obtain the maximum twist angle of blade after this iterative computation, and judge whether the difference of the blade maximum twist angle that this iterative computation obtains and the blade maximum twist angle that last iteration calculates is less than or equal to 0.1 °, if, then meet the condition of convergence, otherwise do not meet the condition of convergence.

Described a kind of stratosphere composite propeller Synthetical Optimization platform, is characterized in that: comprise host computer system, aerodynamic analysis computing module, structural analysis and computation module; Host computer system, aerodynamic analysis computing module become Unified Global with structural analysis and computation module by 100,000,000 Fiber connection; Host computer system comprises main control module, database module and fluid and structural simulation module; By main control module In-put design variate-value, constraint condition and objective function, and run Pneumatic Calculation module, structural calculation module and fluid and structural simulation module; Database module provides access interface for needing the module of accessing database, and database module comprises aerodynamic model database, structural model database and fluid structure interaction mode database.

Beneficial effect

The present invention can the pneumatic and structural design of coordination optimization, and the stratosphere composite propeller Synthetical Optimization problem of fluid structurecoupling is considered in process, and that considers pneumatic and structure to stratosphere screw propeller requires very strong specific aim.The present invention, by considering the feedback of fluid structurecoupling, can obtain pneumatic, the structural model of global optimum.By having the data transmission of each intermodule of unified interface standard, efficiently solve each intermodular data communication difficult, the automatic synchronization achieving each module relating to pneumatic and structure subject runs.

Utilize this invention in pneumatic, structure optimization, consider the requirement of fluid structurecoupling in the design phase of stratosphere screw propeller, the impact of elastic deformation on pneumatic design and structural design can be obtained, thus fine reference role is played to the determination of its next step Fine design scheme.Utilize this invention just can utilize interaction between pneumatic, structure subject in the concept phase, design and not only meet pneumatic efficiency requirements weight but also light structure simultaneously; Simultaneously by realizing pneumatic, structure-integrated design, can effectively solve in traditional separately design when structure optimization and pneumatic design conflict, fluid structurecoupling convergence can not be reached and negate the problem of a large amount of previous work, shortening the design cycle, improve design efficiency.

Accompanying drawing explanation

Accompanying drawing 1 is the hardware composition frame chart of the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling.

Accompanying drawing 2 is the operational flow diagram of the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling.

Accompanying drawing 3 is the Pneumatic Calculation module detailed design explanations of the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling.

Accompanying drawing 4 is the structural calculation module detailed design explanations of the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling.

Accompanying drawing 5 is the fluid and structural simulation module detailed design explanations of the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling.

Accompanying drawing 6 is detailed design explanations that the response surface of the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling is set up.

Accompanying drawing 7 is pneumatic, the structure global optimization detailed design explanation of the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling.

Accompanying drawing 8 is that analysis result output module program describes in detail.

Embodiment

Below in conjunction with specific embodiment, the present invention is described:

The present embodiment constitutes the stratosphere composite propeller Synthetical Optimization platform considering fluid structurecoupling by 3 computing machines.As shown in Figure 1,1 is host computer system, and 2 is aerodynamic analysis computer system, and 3 is structural analysis and computation machine system.Hardware system described in the present embodiment comprises host computer system, aerodynamic analysis computer system and structure analysis computer system becomes Unified Global by 100,000,000 Fiber connection.By the main control module of host computer system as operating system of user, comprise main control module, database module and fluid and structural simulation module, wherein main control module and fluid and structural simulation module are control module, the structural analysis and computation module of the aerodynamic analysis computing module and structural analysis and computation machine system that call aerodynamic analysis computer system carries out analytical calculation, and adopts database module to store data.Data exchange interface between each module and database module adopts standardization.Wherein database module is the intermediary that modules exchanges data mutually, and main control module is responsible for the work coordinating each module.

Database module, in order to initialization data library structure, provides access interface for needing the sub-module of accessing database.Database module includes aerodynamic model database, this database in order to design Storage initially with the data relevant to aerodynamic optimization model in process of optimization; Structural model database, this database is used for the data that model of structural optimization is relevant in Optimization Storage Design process; Fluid structure interaction mode database, this database is used for storing the data that in iterative process, aerodynamic model is relevant with structural model; The access interface that database management module provides is standardized, mutually exchanges data between each sub-module and database according to this standard interface, coordinates modules.

And concrete method step is as follows:

Step 1: choose design variable:

In the present embodiment, the pneumatic design of screw propeller refers to that paddle type designs: determining that number of blade is 2, under the prerequisite of given diameter of propeller blade, optimizes chord length distribution and torsion angle distribution, makes the efficiency of screw propeller reach optimum.Therefore, design variable is decided to be chord length distribution and torsion angle distribution.

Because stratosphere screw propeller adopts the symmetrical structure of two leaf oars, the parameter of single bladed paddle only need be optimized.In the present invention, single bladed paddle leaf is divided for from blade root to blade tip and control section by 12, definition screw propeller rotation center is the position of location and installation axle, the position of other sections is by the ratio of radius residing for each section (distance of distance installation shaft) relative to propeller radius, and namely relative radius determines the position of each section.Screw propeller comprises propeller hub and blade, because the design of propeller hub is not significantly contributed for the improvement of aeroperformance, therefore the present invention only considers the paddle type design of blade.Because the size of propeller hub is included in the diameter of screw propeller, skim and give propeller hub reserved size, so the blade root of blade is positioned at 20% place, blade tip is positioned at 100% place, and each section is not equally distributed, but according to the significance level that erect-position improves for aeroperformance, be divided into two regions to arrange and control section.Arrange that controls a section from blade root to 70% every 10%, arrange that controls a section from 70% to blade tip every 5%.The information that control section comprises has: baseline airfoil, chord length and torsion angle.Wherein, baseline airfoil is unit chord length and torsion angle is the aerofoil profile parametrization coordinate information of 0 degree; Chord length is by the chord length of aerofoil profile after baseline airfoil convergent-divergent; Torsion angle is that baseline airfoil reverses the required angle reversed of a certain angle.Connected by SPL between each control section, smooth paddle type can be generated.Given 12 of the present invention controls section baseline airfoil, optimizes paddle type by the chord length and propeller pitch angle optimizing each section.Consider 12 section chord lengths and propeller pitch angle totally 24 variablees, should not to control and quantity is too large, so plan quafric curve of the present invention describes the chord length distribution of blade, do the fairing that not only can ensure blade profile like this but also make problem be simplified process.In view of the screw propeller studied controls the blade chord length regularity of distribution of section, the curve describing blade chord length distribution in the present invention is described by two sections of quafric curves, one section be blade root to maximum chord length present position, another section is that maximum chord length present position is to blade tip.And expression formula is respectively: y ₁=a (x-x _max) ²+ y _maxand y ₂=b (x-x _max) ²+ y _max, wherein x _maxradius residing for maximum chord length, y _maxfor maximum chord length, x is for controlling the radial location residing for section, y ₁, y ₂for each control section chord length.Rule of thumb, in view of the maximal value of two sections of quafric curves is all in maximum chord length present position, therefore only need determine that radius residing for maximum chord length and chord length, blade root place chord length and blade tip place chord length four variablees can obtain a and b, and then determine two sections of quafric curves, thus obtain according to the absolute radius of each control section the chord length distribution that whole blade controls section.Meanwhile, in the present invention, plan quafric curve describes the propeller pitch angle distribution of blade.Expression formula is: y ₃=cx ²+ dx+e.Wherein x is for controlling the radial location residing for section, y ₃for propeller pitch angle.Only need determine that blade root place propeller pitch angle, the propeller pitch angle of maximum chord length present position and blade tip place propeller pitch angle three variablees can determine the expression formula of quafric curve.

So the pneumatic design variable chosen is the propeller pitch angle of the radial location residing for propeller blade maximum chord length, propeller blade maximum chord length, screw propeller blade root place chord length, screw propeller blade tip place chord length, screw propeller blade root place propeller pitch angle, screw propeller blade tip place propeller pitch angle, propeller blade maximum chord length present position.The span of the radial location residing for maximum chord length is: 50%R-80%R; The span of maximum chord length is: 0.1R-0.2R; The span of blade root place chord length is: 0.05R-0.2R; The span of blade tip place chord length is: 0.02R-0.1R.Wherein R is blade radius.The span of blade root place propeller pitch angle is: 25 °-45 °; The span of blade tip place propeller pitch angle is: 5 °-10 °; The propeller pitch angle span of maximum chord length present position is 10 °-15 °.

In the present embodiment, blade is laterally divided into 11 by the control section number described in aerodynamic optimization by propeller arrangement and optimizes regions, determine the laying angle of the laying number of plies in each region, every one deck and material properties and then obtain the structural information of screw propeller.But 33 design variables like this, not only quantity is large but also complicated owing to considering the constraint rule such as continuity, globality of composite plys between each variable, adds design process difficulty and complexity.Consider that screw propeller is that slender bodies cuts Rotating fields, propose with laying group number in the present invention, the laying number of plies of each laying group, the laying angle of each laying group, the laying distance of each laying group, the material of each laying group is design variable, optimize this simultaneously and singlely add four groups of variablees, obtain to optimize ply stacking-sequence and thickness simultaneously, the continuity of fiber can be ensured, the compound substance that typical case that stress concentrates is applicable to slender bodies propeller arrangement can be reduced and cut Rotating fields, reduce design variable number, and the coupling do not existed between variable and restriction.In the present invention, namely the concept of laying group can be reduced to the laying number of plies of critical area (blade root place the 1st optimizes region), and often group spreads n layer (n<4) at most; The concept of laying group angle is the laying angle of each laying group of critical area, and often the interior paving of group is identical to angle, to ensure the continuity of fiber; The concept of laying group laying distance can be reduced to that laying group can extend to which to optimize the number in region, and the maximum laying distance of laying group is for optimizing areal, to ensure the Rotating fields of cutting of slender bodies screw propeller; The material of laying group can be reduced to laying group and compose material properties.

Step 2: use Latin hypercube experimental design method value in the span of design variable, obtain some samples.

Step 3: for each group sample point, the pneumatic design variable extracted wherein carries out Pneumatic Calculation, and the structural design variable extracted wherein carries out Structure Calculation, and consider the impact of fluid structurecoupling in Structure Calculation.

Step 3.1: control section by 12 and propeller blade is divided into 11 regions along exhibition to direction; According to 7 pneumatic design variablees and propeller blade chord length, propeller pitch angle along blade exhibition to the regularity of distribution in direction, obtain chord length and propeller pitch angle that 12 control section, and adopt the mode of Quadric spline curve matching to obtain the aerodynamic configuration of propeller blade between adjacent control section, set up the aerodynamic model of propeller blade, and enter step 3.2 with this aerodynamic model.

Step 3.2: based on the propeller blade aerodynamic model entering this step, by solving the averaged Navier-Stokes equation under absolute coordinate system based on the fully implicit solution dual time method introducing Multigrid Technique and exercise testing technology that contain the sub-iteration of newton-type, numerical simulation screw propeller axial flow Viscous Flow, obtains the pneumatic distributed force of screw propeller under axial flow state, pulling force, power, torque and efficiency.

In the present embodiment, Pneumatic Calculation is the calculating under blade is in axial flow state, and calculate and only need carry out a blade, the impact of another blade is realized by periodic boundary condition.Conveniently catch trailing vortex and implementation cycle property boundary condition, adopt chimera grids.Computing grid comprises two covers: the blade grid of C-H type and the background grid of H-H type.Blade grid, for simulating VISCOUS FLOW, catches near field trailing vortex; The net point in two swing circle faces of background grid is one to one, and this enforcement for swing circle boundary condition is very easily.The present invention by experiment method for designing chooses initial sample point in the respective span of seven pneumatic design variablees, structure y ₁, y ₂and y ₃three One-place 2-th Order curves, 12 chord length and propeller pitch angle information controlling section can be determined in the relative radius position residing for each section.The foundation of aerodynamic model can be described by following steps:

(1) by controlling structure SPL between section every two adjacent control sections at 12, the actual geometric model of blade is obtained.

(2) blade surface grid is generated, by controlling section adopts identical spline method again to layout at 12, suitably encrypt in leading edge and trailing edge, along exhibition to direction between each control section uniform stationing, blade surface grid can be obtained by three-dimensional spline interpolation.

(3) generate blade space lattice, blade grid is C-H type grid, and generates H type grid along exhibition to direction, generates C type grid along chordwise direction.Blade grid, for simulating VISCOUS FLOW, catches near field trailing vortex.

(4) generation background grid, background grid is H-H type grid, and the net point in two of background grid swing circle faces is one to one.

(5) determine the nest relation of grid, the grid cell in the nested grid system that in the present invention, blade grid and background grid form is divided into calculation level, hole frontier point, hole point, artificial outer boundary, some classes such as artificial inner boundary, physical boundary etc.:

5-1) calculation level refers to the point being arranged in nested grid system computational fields inside, participates in flow field iterative for discrete;

5-2) border, hole refers to that background grid exists border, hole on blade grid, and flow variables interpolation from blade grid of these unit obtains.

5-3) hole point refers to the point being positioned at hole border inner.These points do not participate in flowing and calculate.

5-4) artificial outer boundary refers to that blade grid outer boundary is exactly artificial outer boundary, and its value interpolation from background grid obtains.

5-5) physical boundary comprises far field boundary, object plane border.

(6) aeroperformance carrying out screw propeller calculates.It is obtain under the flowing of axial flow state that propeller of the present invention calculates, and can think a kind of quasi-steady flow.The present invention's employing is fixed on the governing equation of the integrated form under rotating coordinate system:

$\frac{\&PartialD;}{\&PartialD;t}\underset{\mathrm{\&Omega;}}{\&Integral;\&Integral;\&Integral;}\mathrm{WdV}+\underset{\&PartialD;\mathrm{\&Omega;}}{\&Integral;\&Integral;}\stackrel{=}{H^{\text{'}}}\&CenterDot;\mathrm{ndS}-\underset{\&PartialD;\mathrm{\&Omega;}}{\&Integral;\&Integral;}\stackrel{=}{H^{\text{'}}}\&CenterDot;\mathrm{ndS}+\underset{\mathrm{\&Omega;}}{\&Integral;\&Integral;\&Integral;}\mathrm{GdV}=0$

In formula,

$\begin{array}{cc}W=\left[\begin{array}{c}\mathrm{\&rho;}\\ \mathrm{\&rho;u}\\ \mathrm{\&rho;v}\\ \mathrm{\&rho;w}\\ \mathrm{\&rho;E}\end{array}\right]& \stackrel{=}{H^{\text{'}}}\end{array}=\left[\begin{array}{c}\mathrm{\&rho;}(q-q_b)\\ \mathrm{\&rho;u}(q-q_b)+p{I}_x\\ \mathrm{\&rho;v}(q-q_b)+p{I}_y\\ \mathrm{\&rho;w}(q-q_b)+p{I}_z\\ \mathrm{\&rho;H}(q-q_b)+p{q}_b\end{array}\right]$

$\begin{array}{cc}G=\left[\begin{array}{c}0\\ \mathrm{\&rho;}{(\mathrm{\&omega;}\&times;q)}_x\\ \mathrm{\&rho;}{(\mathrm{\&omega;}\&times;q)}_y\\ \mathrm{\&rho;}{(\mathrm{\&omega;}\&times;q)}_z\\ 0\end{array}\right]& \end{array}\stackrel{=}{H_v}=\left[\begin{array}{c}0\\ {\mathrm{\&tau;}}_{\mathrm{xx}}{I}_x+{\mathrm{\&tau;}}_{\mathrm{xy}}{I}_y+{\mathrm{\&tau;}}_{\mathrm{xz}}{I}_z\\ {\mathrm{\&tau;}}_{\mathrm{xy}}{I}_x+{\mathrm{\&tau;}}_{\mathrm{yy}}{I}_y+{\mathrm{\&tau;}}_{\mathrm{yz}}{I}_z\\ {\mathrm{\&lambda;}}_x{I}_x+{\mathrm{\&lambda;}}_y{I}_y+{\mathrm{\&lambda;}}_z{I}_z\\ {\mathrm{\&tau;}}_{\mathrm{xx}}{I}_x+{\mathrm{\&tau;}}_{\mathrm{xy}}{I}_y+{\mathrm{\&tau;}}_{\mathrm{xz}}{I}_z\end{array}\right]$

Wherein, G is that blade rotates the coriolis force source item introduced.ρ, (u, v, w), p, E represent density, three components, pressure, the unit mass total energy of speed under rectangular coordinate system of fluid respectively.Q=(u, v, w) ^tfor fluid velocity vectors, q _b=u _bi _x+ v _bi _y+ w _bi _zfor the movement velocity vector on control volume border, I _x, I _y, I _zbe respectively the unit coordinate vector under rotating coordinate system.

Flow variables is defined in grid cell centers place, and hypothesis is constant on whole unit.In order to improve the accuracy that flux calculates, will be divided into two parts:

$\stackrel{=}{H^{\text{'}}}=\stackrel{=}{H_i}-\stackrel{=}{H_r}$

Wherein

$\begin{array}{cc}\stackrel{=}{H_i}=\left[\begin{array}{c}\mathrm{\&rho;q}\\ \mathrm{\&rho;uq}+p{I}_x\\ \mathrm{\&rho;vq}+p{I}_y\\ \mathrm{\&rho;wq}+p{I}_z\\ \mathrm{\&rho;Hq}\end{array}\right]& \stackrel{=}{H_r}\end{array}=\left[\begin{array}{c}\mathrm{\&rho;}{q}_b\\ \mathrm{\&rho;u}{q}_b\\ \mathrm{\&rho;v}{q}_b\\ \mathrm{\&rho;w}{q}_b\\ \mathrm{\&rho;E}{q}_b\end{array}\right]=W\&CenterDot;q_b$

For the sticky flux of nothing adopt cell centered scheme to carry out discrete herein, and rotate flux the method of resolving is adopted to utilize Stokes formula that Line Integral is converted into line integral.Time stepping method adopts implicit expression LU-SGS.Turbulence model adopts B-L (Baldwin-Lomax) algebraic model.

After Flow Field Calculation convergence, the pneumatic distributed force of aerodynamic grid node can being obtained, the pulling force T of screw propeller, torque M and power P can being obtained, by being transformed into tension coefficient c by integration _t and power coefficient $c_P(c_P=\frac{P}{\mathrm{\&rho;}{N_s}^2{D}^4})$ The efficiency of screw propeller can be obtained $\mathrm{\&eta;}(\mathrm{\&eta;}=\frac{c_T}{c_P}\mathrm{\&lambda;}).$

Step 3.3: based on propeller blade aerodynamic model and four groups of structural design variablees, obtained the structural model of propeller blade by parametric modeling.

Step 3.4: the pneumatic distributed force of step 3.2 gained is transformed on the grid of the structural model of step 3.3 gained, then carries out structure finite element calculating, obtain the stress of propeller blade, strain, frequency, displacement and weight.

Due to aerodynamic model grid and structural model stress and strain model inconsistent, coupling be realized and calculate, need to carry out exchanges data (concrete visible document: aviation journal, Mar between different grid.252013Vol.34No.3541-546 the application of local dynamic station method for interchanging data in wind-structure interaction).In the present invention, first interpolation area is determined.The first step, to each pneumatic site, finds recent topology unit (e) be adjacent.Specific practice is: (1) finds the structure node nearest with it to each pneumatic node, (2) all structural units comprising recent topology point are found out, obtain the vertical range of pneumatic point and each structural unit successively, distance reckling is looked for structural unit.Second step, is adjacent the dihedral angle determination interpolation area between unit according to recent topology unit (e).Specific practice is: (1) brings most proximity structure unit into interpolation scope in, then obtain active cell successively and be adjacent dihedral angle between unit, if angle is less than α (if the value of α is excessive may introduce some noise spots, too small meeting makes interpolation scope too little, capital has influence on the fairness of interpolation rear curved surface, way herein repeatedly attempts a rear selected suitable value according to the curvature of curved surface and the thickness of grid), then find out the common node of two unit forming dihedral angle.(2) all unit comprising common node are included in interpolation scope, (triangle grid comprises at most 12 nodes to whole nodes that within the scope of interpolation, all unit comprise, quadrilateral mesh comprises at most 16 nodes), be last interpolation area.After interpolation region is determined, the transmission multiple spot of aerodynamic force chooses method, and its basic thought is from nearest some load of structure overabsorption of pneumatic point, otherwise distributes less.For pneumatic some j, suppose with it at a distance of being L _isystem point between exist one with pneumatic virtual semi-girder, system point is assigned to load p _itime deformation energy be:

$U_i=\frac{1}{6\mathrm{EJ}}{P}_i^2{L}_i^3$

In formula, EJ is the bending strength of beam, so the deformation energy of whole system is:

$U=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{U}_i$

Being assigned to load on system point should make the deformation energy of system minimum, and meets static(al) equivalence principle.

$\begin{array}{cc}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{P}_i=P_j& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{P}_i\&CenterDot;x_i=P_j\&CenterDot;y\end{array}$

$\begin{array}{cc}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{P}_i\&CenterDot;y_i=P_j\&CenterDot;y_j& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{P}_i\&CenterDot;z_i=P_j\&CenterDot;z_j\end{array}$

Set up Lagrangian function:

$G(\mathrm{\&lambda;},{\mathrm{\&lambda;}}_x,{\mathrm{\&lambda;}}_y,{\mathrm{\&lambda;}}_z)=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}(\frac{1}{6\mathrm{EJ}}{P}_i^2{L}_i^3-\mathrm{\&lambda;}{P}_i-{\mathrm{\&lambda;}}_x{P}_i\stackrel{\&OverBar;}{x_i}-{\mathrm{\&lambda;}}_y{P}_i\stackrel{\&OverBar;}{y_i}-{\mathrm{\&lambda;}}_z{P}_i\stackrel{\&OverBar;}{z_i})$

In formula

$\begin{array}{ccc}\stackrel{\&OverBar;}{x_i}=x_i-x_j& \stackrel{\&OverBar;}{y_i}=y_i-y_j& \stackrel{\&OverBar;}{z_i}=z_i-z_j\end{array}$

Order

$\frac{\&PartialD;}{\&PartialD;P_i}G(\mathrm{\&lambda;},{\mathrm{\&lambda;}}_x,{\mathrm{\&lambda;}}_y,{\mathrm{\&lambda;}}_z)=0$

And make 3EJ=1 and get final product:

$P_i{L}_i^3=\mathrm{\&lambda;}+{\mathrm{\&lambda;}}_x\stackrel{\&OverBar;}{x_i}+{\mathrm{\&lambda;}}_y\stackrel{\&OverBar;}{y_i}+{\mathrm{\&lambda;}}_z\stackrel{\&OverBar;}{z_i}$

Bring static(al) equivalent condition into obtain:

$\left[\begin{array}{cccc}\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\stackrel{\&OverBar;}{x_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\stackrel{\&OverBar;}{y_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}\stackrel{\&OverBar;}{z_i}{L}_i^{-3}\\ \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{x}_i{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{x}_i\stackrel{\&OverBar;}{x_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{x}_i\stackrel{\&OverBar;}{y_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{x}_i\stackrel{\&OverBar;}{z_i}{L}_i^{-3}\\ \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{y}_i{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{y}_i\stackrel{\&OverBar;}{x_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{y}_i\stackrel{\&OverBar;}{y_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{y}_i\stackrel{\&OverBar;}{z_i}{L}_i^{-3}\\ \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{z}_i{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{z}_i\stackrel{\&OverBar;}{x_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{z}_i\stackrel{\&OverBar;}{y_i}{L}_i^{-3}& \underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{z}_i\stackrel{\&OverBar;}{z_i}{L}_i^{-3}\end{array}\right]\&bull;\left[\begin{array}{c}\mathrm{\&lambda;}\\ {\mathrm{\&lambda;}}_x\\ {\mathrm{\&lambda;}}_y\\ {\mathrm{\&lambda;}}_z\end{array}\right]=\left[\begin{array}{c}{p}_j\\ p_j\&CenterDot;x_j\\ p_j\&CenterDot;y_j\\ p_j\&CenterDot;z_j\end{array}\right]$

Try to achieve λ _x, λ _y, λ _z, the load p on pneumatic site j can be obtained _jbe assigned to the load p on system point _i.

And structure finite element calculates the parameterized finite element structure computation model of employing in the present invention:

(1) stress and strain model.On the basis of pneumatic geometric model, structured grid division is carried out to model, upwards arrange grid node uniformly at control section and exhibition, form uniform structuring quadrilateral mesh.For the ease of analyzing, in the present invention, unified propeller hub is set for all blades, and forms unstructured quadrilateral mesh at propeller hub place.

(2) cell attribute of each grid cell is set.Be that each grid cell gives the composite plys number of plies, angle and material information by optimization region.

(3) impose restriction.The constraint that can retrain translation and rotate six-freedom degree direction is applied at propeller hub place.

(4) external force is applied.The next aerodynamic force distribution of aerodynamic model-structural model load transfer is applied across at blade surface.

(5) the element displacement matrix that the polynomial expression generating description unit displacement attribute describes.Equilibrium condition is utilized to derive the stiffness matrix [k] of unit e ^(e)with load vectors p ^(e).

(6) aggregation units equation obtains total balance equation group.Unit stiffness matrix and load vectors are combined by appropriate ways, thus sets up the system of equations of following form: [k] { δ }={ P} obtains global stiffness balance equation.Wherein, [k] is called global stiffness matrix; { δ } is integrally-built displacement of joint; { P} acts on the external force on the finite element node of total.

(7) unknown displacement of joint is solved.Change total balance equation by the boundary condition of problem, structure can not be moved by rigid body, thus solve displacement of joint { δ }.

(8) calculating of unit strain and stress.The strain and stress of the relevant equation calculated unit of solid mechanics or structural mechanics can be utilized according to the displacement of joint of known point.

(9) integration is carried out to the displacement of each unit, stress and strain and obtain the stress of whole screw propeller, strain, frequency, maximum displacement and weight information.

Step 3.5: structural model grid displacement step 3.4 obtained is transformed on aerodynamic model surface mesh, obtain new aerodynamic model surface mesh, and judge whether to meet the condition of convergence, if do not meet the condition of convergence, return step 3.2 with the new aerodynamic model surface mesh obtained, if meet the condition of convergence, end step 3, obtain the response that this group sample point is corresponding, described response is the Pneumatic Calculation result meeting the condition of convergence: the pneumatic distributed force of screw propeller under axial flow state, pulling force, power, torque and efficiency, and meet the Structure Calculation result of the condition of convergence: the stress of propeller blade, strain, frequency, displacement and weight.

The above-mentioned condition of convergence is: the propeller blade displacement calculated according to this structure finite element, obtain the maximum twist angle of blade after this iterative computation, and judge whether the difference of the blade maximum twist angle that this iterative computation obtains and the blade maximum twist angle that last iteration calculates is less than or equal to 0.1 °, if, then meet the condition of convergence, otherwise do not meet the condition of convergence.

Under the running status of screw propeller reality, elastic deformation will inevitably be produced under Aerodynamic force action, such distortion can cause again the distribution of body structure surface upper aerodynamic power, the change of aerodynamic profile makes again structure produce new elastic deformation, the mutual distortion that the interaction of this aerodynamic force and structural elasticity power produces may be tending towards convergence, finally reaches equilibrium state; Also may be tending towards dispersing and causing structural failure, therefore consider that the impact of fluid structure interaction is very important at the structured design phase of screw propeller.

The calculating of the consideration fluid structurecoupling in the present invention carries out after the FEM (finite element) calculation completing primary structure model, after completing a FEM (finite element) calculation, the stress of screw propeller, strain, grid node displacement information can be extracted, and then carry out by the conversion of structural model grid to the displacement on aerodynamic model grid, what first will do before positional displacement interpolation is the determination of interpolation area.The first step, to each pneumatic site, finds recent topology unit (e) be adjacent.Specific practice is: (1) finds the structure node nearest with it to each pneumatic node, (2) all structural units comprising recent topology point are found out, obtain the vertical range of pneumatic point and each structural unit successively, distance reckling is looked for structural unit.Second step, is adjacent the dihedral angle determination interpolation area between unit according to recent topology unit (e).Specific practice is: (1) brings most proximity structure unit into interpolation scope in, then obtain active cell successively and be adjacent dihedral angle between unit, if angle is less than α (if the value of α is excessive may introduce some noise spots, too small meeting makes interpolation scope too little, capital has influence on the fairness of interpolation rear curved surface, way herein repeatedly attempts a rear selected suitable value according to the curvature of curved surface and the thickness of grid), then find out the common node of two unit forming dihedral angle.(2) all unit comprising common node are included in interpolation scope, (triangle grid comprises at most 12 nodes to whole nodes that within the scope of interpolation, all unit comprise, quadrilateral mesh comprises at most 16 nodes), be last interpolation area.

After interpolation area is determined, the interpolation TPS method of displacement.Thin flat plate batten W (x, y, z) is considered to the infinite slab by given nodal displacement Wi.The static balancing differential equation relevant with plane load to flexural deformation is:

$D{\&dtri;}^{4}W=q$

D represents dull and stereotyped elasticity coefficient, and q is dull and stereotyped distributed load.Obtain after arranging:

$W(x,y,z)=a_0+a_{1}x+a_{2}y+a_{3}z+\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{F}_i{r}_i^2\ln r_i^2$

In formula:

$r_i^2={(x-x_i)}^2+{(y-y_i)}^2+{(z-z_i)}^2$

N+4 unknown number can have two formulas below to determine:

$\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{F}_i=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{x}_i{F}_i=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{y}_i{F}_i=\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{z}_i{F}_i=0$

$\begin{array}{cc}{W}_j=a_0+a_1{x}_j+a_2{y}_j+a_3{z}_j+\underset{i=1}{\overset{N}{\mathrm{\&Sigma;}}}{F}_i{r_{\mathrm{ij}}}^2\ln {r_{\mathrm{ij}}}^2& j=\mathrm{1,2},...,N\end{array}$

Try to achieve interpolation coefficient and substitute into the displacement that above formula can obtain pneumatic node later.

After obtaining the displacement of pneumatic node, be added on original aerodynamic model mesh point coordinate and obtained new aerodynamic configuration, iteration, until meet the elasticity condition of convergence, export the stress of screw propeller now, strain, frequency, maximum displacement and weight information, in order to follow-up set up agent model time use.

Step 4: it is complete whether some samples that determining step 2 obtains all calculate, if do not calculate complete, returns and performs step 3, otherwise set up sample set with some samples that step 2 obtains, and enter step 5 with this sample set.

Step 5: according to entering the response structure Kriging agent model that in the sample set of this step and sample set, sample is corresponding, and enter step 6 with this agent model.

Because in the present invention, although design variable is through reduction in various degree, but still belong to the category that design variable is large, and it is more discrete, so the present invention is based on agent model technology, by the method for test design, obtain the sample point corresponding to design variable, by calling analytical model (structural model or aerodynamic model), calculate the response corresponding to design variable sample point, the response corresponding to all sample points is gone out according to this process computation, these numerical value calculated are utilized to set up agent model, optimized algorithm is adopted to be optimized acquisition optimum solution based on agent model.

Step 6: based on the agent model entering this step, adopts genetic algorithm to be optimized:

Step 6.1: initial population scale and maximum evolutionary generation are set, and optimization object function and the constraint condition of setting up pneumatic and Structure Calculation; Described optimization aim is: pneumatic efficiency is the highest, weight is the lightest, frequency is the highest; Described constraint condition is: pneumatic restraint condition: power is not more than the peak power output of screw propeller drive motor, and torque is not more than the torque capacity that screw propeller drive motor can provide; Structure constraint: stress, strain meet the requirement of laminated material own.

Step 6.2: adopt mixing floating-point encoding method to encode to pneumatic design variable, adopt the method for integer coding to encode to structural design variable, the coding mapping of pneumatic design variable and structural design variable is become a gene string.

By the floating number chromosome becoming a type arranged together in above mentioned 7 pneumatic design variable specified scopes.4*p+1 structural design variable is made up of (p is the laying number of plies) the chromosome of two types: critical area chromosome and control chromosome.Wherein, critical area chromosome is two, is respectively laying group laying angle chromosome and laying group dyeing material body.Wherein, laying group laying angle chromosome is used for encoding to angle to the paving of each laying group, the concrete numerical value to angle is spread: laying group dyeing material body is used for encoding to the material of each laying group with the representative of different integers, the association attributes of different materials shifts to an earlier date assignment to different integer, represents different materials with different integer.Controlling chromosome is two, is respectively the laying group number of plies and controls chromosome and laying group laying distance controlling chromosome.Wherein, the laying group number of plies controls chromosome function and is: the integer coding function containing scale-of-two " switch " chromosome function, is specially: when its scale-of-two " switch " is for off status, represents the corresponding laying group number of plies and does not exist; When its scale-of-two " switch " is for open state, have a non-zero value, this non-zero value represents corresponding laying group number of plies value; Laying group laying distance controlling chromosome function is: the integer coding function containing scale-of-two " switch " chromosome function, is specially: when its scale-of-two " switch " is for off status, and representing corresponding laying group laying distance is 0; When its scale-of-two " switch " is for open state, there is a non-zero value, the optimization subfield value that the representative of this non-zero value is laid from root.

In the present invention, the paving of each laying group is controlled to angle θ by integer coding, discrete paving is converted into integer process to angle, as: set each laying group to spread span to angle for [-67.5,112.5], when generation gene string, a random number is produced within the scope of this, if when the numerical value of this random number is between [-67.5 ,-22.5], laying group paving is-45 ° to the value at angle; When the random number produced is between [-22.5,22.5], laying group paving is 0 ° to the value at angle; When the random number produced is between [22.5,67.5], laying group paving is 45 ° to the value at angle; And when the random number produced is between [67.5,112.5], laying group paving is 90 ° to the value at angle.In actual optimization, with 1,2,3,4} representative-45 °, and 0 °, 45 °, 90 ° }.Laying group laying distance variable and laying group spread to angle variable processing mode in like manner.In the present invention, have 11 and optimize region, the span of laying group laying distance is [0,12], if the random number generated is in [i, i+1] scope, then this laying group lays front i region, and namely the value of laying group laying distance is i.If random number is in [0,1] scope, then this laying group does not exist, and namely the value of laying group laying distance is 0; If in [1,2] scope, this laying group only lays first region; If random number is in [11,12] scope, then laying group lays all 11 regions, and namely the value of laying group laying distance is 11.The laying group number of plies becomes and belongs to discrete variable with the material of laying group, therefore encodes to each laying group number of plies and material with integer, the field of definition value of the laying group number of plies can be 0,1,2,3,4}; As got 0, represent that this laying group does not exist, as got, { 1,2,3,4} represents in this laying group have 1/2/3/4 laying individual layer respectively.The field of definition value of the material of laying group can be 1,2,3,4}, as represented material 1 with 1, representing material 2 with 2, representing material 3 with 3, represent material 4 with 4.

Step 6.3: set up fitness function according to the optimization object function of step 6.1 and constraint condition; The initial population that random generation is made up of N number of gene string, and enter step 6.4 with initial population.

Step 6.4: using adaptability function is assessed the population entering this step, obtains the highest C of a fitness value gene string; Crossover and mutation operation is carried out to C the gene string obtained, obtains population of new generation.

Step 6.5: judge whether to reach maximum evolutionary generation, if do not reach maximum evolutionary generation, then return step 6.4 with population of new generation, carry out another generation evolution, if reach maximum evolutionary generation, then the maximum adaptation degree gene string obtained in evolutionary process is decoded, obtain optimum sample.

Step 7: adopt the Pneumatic Calculation of step 3 and structure computation method to obtain the response of optimum sample; Calculate the response of the optimum sample that this suboptimization obtains and the last difference optimizing the response of the optimum sample obtained, and judge whether the difference ratio of the response of optimum sample that suboptimization obtains therewith is not more than 1%, if, then export optimum sample and response thereof that this suboptimization obtains or lastly optimize the optimum sample and response thereof that obtain, otherwise, the optimum sample this suboptimization obtained adds sample set, obtains new sample set; Step 5 is returned with new sample set.

After exporting optimum sample and response thereof, decode, obtain 12, screw propeller and control section chord length and torsion angle, and the composite plys information in 11 regions.

As shown in Figure 2, the stratosphere composite propeller Synthetical Optimization platform of the consideration fluid structurecoupling described in the present embodiment comprises main control module, the Pneumatic Calculation module based on N-S equation, the structural calculation module based on finite element, fluid and structural simulation module and database module.Data exchange interface between each module and database module adopts standardization.Wherein database module is the intermediary that modules exchanges data mutually, and main control module is responsible for the work coordinating each module.After setting up data interface standard, concrete implementation is as follows:

First the present embodiment performs step 1000, determines pneumatic, the structural design variable of screw propeller and its respective span; Perform step 2000, adopt Latin hypercube experimental design method to choose pneumatic and initial sample point that is structure optimization parameter; Perform step 3000, for a certain or certain several sample point; Perform step 4000, adopt multithreads computing to carry out the Pneumatic Calculation of sample point; Perform step 5000, adopt multithreads computing to carry out the Structure Calculation of sample point; Perform step 6000, adopt multithreads computing to carry out the fluid and structural simulation of sample point; Perform step 7000, after fluid and structural simulation convergence, the pneumatic of sample point and structural response is recorded in database module, and judge whether the response of all sample points calculates complete, if do not calculate complete, continue to perform step 3000-7000, if calculate complete, continue to perform following steps; Perform step 8000, by all sample points and response thereof, adopt agent model to set up response surface; Perform step 9000, select suitable to add point methods; Perform step 10000, be optimized by genetic algorithm; Perform step 11000, obtain new sample point; Perform step 12000, adopt multithreads computing to carry out the Pneumatic Calculation of sample point; Perform step 13000, adopt multithreads computing to carry out the Structure Calculation of sample point; Perform step 14000, adopt multithreads computing to carry out the fluid and structural simulation of sample point; Perform step 15000, judge whether to meet stopping criterion, if not then repeated execution of steps 8000-15000; If then perform step 16000, export screw propeller finally pneumatic and Optimal Structure Designing scheme.

As shown in Figure 3, when performing step 4000 and 12000 and carrying out the Pneumatic Calculation of screw propeller: first perform step 4100, the sample points certificate of input aerodynamic optimization parameter and pneumatic controling parameters; Perform step 4200, generate propeller contour model; Perform step 4300, generate blade surface grid; Perform step 4400, generation background grid, the size in far field gets 10 times of blade radiuses; Perform step 4500, generate the middle transition grid rotated relative to background grid, cylindrical radius gets 2 times of blade radiuses, highly gets 2-3 times of blade radius; Perform step 4600, use finite volume method to solve time-dependent average Navier-Stokes equation numerical simulation screw propeller Viscous Flow; Perform step 4700, in aerodynamic data library module, record screw propeller often organizing the pneumatic efficiency under sample point, demand power, demand torque.

As shown in Figure 4, when performing step 5000 and 13000 and carrying out the Structure Calculation of screw propeller: first perform step 5100, the aerodynamic configuration model of input structure Optimal Parameters, step 4100 gained and propeller hub size; Perform step 5200, build the parametric modeling of propeller arrangement model; Perform step 5300, the pneumatic pressure of step 4700 gained to be distributed the distributed force be transformed on structured grid node by load transfer; Perform step 5400, call finite-element structure analysis program, finite element analysis is carried out to propeller arrangement model; Perform step 5500, in structured data library module, record the heavy information of the frequency of screw propeller, stress, strain, maximum displacement and oar.

As shown in Figure 5, in execution step 6000 and 14000, when carrying out the wind-structure interaction calculating of screw propeller: first perform step 6100, according to the structured grid nodal displacement of step 5500 gained, call displacement interpolation procedure, be interpolated into the deflection on aerodynamic grid node, form new aerodynamic grid model; Perform step 6200, the Pneumatic Calculation program called based on N-S equation calculates, and obtains the distribution of aerodynamic grid node pressure; Perform step 6300, in the new aerodynamic configuration generated according to step 6100 and step 5100, the structure optimization parameter of input remains unchanged and carries out structure parameterization modeling; Perform step 6400, call load transfer program, the distribution of the aerodynamic grid node pressure of step 6200 gained is transformed into the pressure distribution of structured grid node; Perform step 6500, the structural computing program called based on finite element calculates; Perform step 6600, obtain the maximum displacement of structure node displacement and structure node; Perform step 6700, judge whether maximum displacement restrains, then continue execution 6100-6600 if not, if then export structure model.

As shown in Figure 6, when the present embodiment execution step 8000 constructs agent model: first perform step 7000, whether the response inquiring about all sample points calculates complete: if not, continue to perform step 3000-7000; Otherwise, perform step 8200, selected agent model kind; Performing step 8300, is agent model setting constructing variable; Perform step 8400, the agent model needed for structure; Perform step 8500, structure result is preserved and sends agent model and construct complete message.

As shown in Figure 7, when the present embodiment execution step 9000 and 10000 carries out agent model optimizing: first perform step 9200, selected type of adding some points; Performing step 9300, is setting constructing variable of adding some points; Perform step 9400, perform and add point process accordingly; Perform 10100, selected suitable optimization method; Perform step 10200, be corresponding optimization method setup parameter, carry out optimizing; Perform step 10300, obtain optimizing result, preserve and send optimizing end.

As shown in Figure 8, set forth 16000 modules in example, optimum results data outputting module, be mainly used for pneumatic and Optimal Structure Designing result data output.First perform step 16200, the parameter of correlation output is set, such as output variable, form etc.; Then 16300 are performed, export propeller design parameter scheme and Pneumatic Calculation result thereof, then perform step 16400, export propeller arrangement design parameter scheme and Structure Calculation result thereof, finally perform step 16500, carry out the visualization processing of propeller and structural design scheme.

Claims (4)

1. a stratosphere composite propeller Synthetical Optimization method, is characterized in that: comprise the following steps:

Step 1: choose design variable:

Pneumatic design variable is the propeller pitch angle of the radial location residing for propeller blade maximum chord length, propeller blade maximum chord length, screw propeller blade root place chord length, screw propeller blade tip place chord length, screw propeller blade root place propeller pitch angle, screw propeller blade tip place propeller pitch angle, propeller blade maximum chord length present position;

Structural design variable is: the laying distance of the laying number of plies of laying group number, each laying group, the laying angle of each laying group, each laying group, the material of each laying group;

Step 2: use Latin hypercube experimental design method value in the span of design variable, obtain some samples;

Step 3: for each group sample point, the pneumatic design variable extracted wherein carries out Pneumatic Calculation, and the structural design variable extracted wherein carries out Structure Calculation, and consider the impact of fluid structurecoupling in Structure Calculation:

Step 3.1: control section by 12 and propeller blade is divided into 11 regions along exhibition to direction; According to 7 pneumatic design variablees and propeller blade chord length, propeller pitch angle along blade exhibition to the regularity of distribution in direction, obtain chord length and propeller pitch angle that 12 control section, and adopt the mode of Quadric spline curve matching to obtain the aerodynamic configuration of propeller blade between adjacent control section, set up the aerodynamic model of propeller blade, and enter step 3.2 with this aerodynamic model;

Step 3.2: based on the propeller blade aerodynamic model entering this step, by solving the averaged Navier-Stokes equation under absolute coordinate system based on the fully implicit solution dual time method introducing Multigrid Technique and exercise testing technology that contain the sub-iteration of newton-type, numerical simulation screw propeller axial flow Viscous Flow, obtains the pneumatic distributed force of screw propeller under axial flow state, pulling force, power, torque and efficiency;

Step 3.3: based on propeller blade aerodynamic model and four groups of structural design variablees, obtained the structural model of propeller blade by parametric modeling;

Step 3.4: the pneumatic distributed force of step 3.2 gained is transformed on the grid of the structural model of step 3.3 gained, then carries out structure finite element calculating, obtain the stress of propeller blade, strain, frequency, displacement and weight;

Step 3.5: structural model grid displacement step 3.4 obtained is transformed on aerodynamic model surface mesh, obtain new aerodynamic model surface mesh, and judge whether to meet the condition of convergence, if do not meet the condition of convergence, return step 3.2 with the new aerodynamic model surface mesh obtained, if meet the condition of convergence, end step 3, obtain the response that this group sample point is corresponding, described response is the Pneumatic Calculation result meeting the condition of convergence: the pneumatic distributed force of screw propeller under axial flow state, pulling force, power, torque and efficiency, and meet the Structure Calculation result of the condition of convergence: the stress of propeller blade, strain, frequency, displacement and weight,

Step 4: it is complete whether some samples that determining step 2 obtains all calculate, if do not calculate complete, returns and performs step 3, otherwise set up sample set with some samples that step 2 obtains, and enter step 5 with this sample set;

Step 5: according to entering the response structure agent model that in the sample set of this step and sample set, sample is corresponding, and enter step 6 with this agent model;

Step 6: based on the agent model entering this step, adopts genetic algorithm to be optimized:

Step 6.1: initial population scale and maximum evolutionary generation are set, and optimization object function and the constraint condition of setting up pneumatic and Structure Calculation; Described optimization aim is: pneumatic efficiency is the highest, weight is the lightest, frequency is the highest; Described constraint condition is: pneumatic restraint condition: power is not more than the peak power output of screw propeller drive motor, and torque is not more than the torque capacity that screw propeller drive motor can provide; Structure constraint: stress, strain meet the requirement of laminated material own;

Step 6.2: adopt mixing floating-point encoding method to encode to pneumatic design variable, adopt the method for integer coding to encode to structural design variable, the coding mapping of pneumatic design variable and structural design variable is become a gene string;

Step 6.3: set up fitness function according to the optimization object function of step 6.1 and constraint condition; The initial population that random generation is made up of N number of gene string, and enter step 6.4 with initial population;

Step 6.4: using adaptability function is assessed the population entering this step, obtains the highest C of a fitness value gene string; Crossover and mutation operation is carried out to C the gene string obtained, obtains population of new generation;

Step 6.5: judge whether to reach maximum evolutionary generation, if do not reach maximum evolutionary generation, then return step 6.4 with population of new generation, carry out another generation evolution, if reach maximum evolutionary generation, then the maximum adaptation degree gene string obtained in evolutionary process is decoded, obtain optimum sample;

Step 7: adopt the Pneumatic Calculation of step 3 and structure computation method to obtain the response of optimum sample; Calculate the response of the optimum sample that this suboptimization obtains and the last difference optimizing the response of the optimum sample obtained, and judge whether the difference ratio of the response of optimum sample that suboptimization obtains therewith is not more than 1%, if, then export optimum sample and response thereof that this suboptimization obtains or lastly optimize the optimum sample and response thereof that obtain, otherwise, the optimum sample this suboptimization obtained adds sample set, obtains new sample set; Step 5 is returned with new sample set.

2. a kind of stratosphere composite propeller Synthetical Optimization method according to claim 1, is characterized in that: the span of pneumatic design variable is the radial location residing for propeller blade maximum chord length: 50%R ~ 80%R; Propeller blade maximum chord length: 0.1R ~ 0.2R; Screw propeller blade root place chord length: 0.05R ~ 0.2R; Screw propeller blade tip place chord length: 0.02R ~ 0.1R; Screw propeller blade root place propeller pitch angle: 25 ° ~ 45 °; Screw propeller blade tip place propeller pitch angle: 5 ° ~ 10 °; The propeller pitch angle of propeller blade maximum chord length present position: 10 ° ~ 15 °; R is propeller blade radius.

3. a kind of stratosphere composite propeller Synthetical Optimization method according to claim 1, it is characterized in that: in step 3.5, the condition of convergence is: the propeller blade displacement calculated according to this structure finite element, obtain the maximum twist angle of blade after this iterative computation, and judge whether the difference of the blade maximum twist angle that this iterative computation obtains and the blade maximum twist angle that last iteration calculates is less than or equal to 0.1 °, if, then meet the condition of convergence, otherwise do not meet the condition of convergence.

4. a stratosphere composite propeller Synthetical Optimization platform, is characterized in that: comprise host computer system, aerodynamic analysis computing module, structural analysis and computation module; Host computer system, aerodynamic analysis computing module become Unified Global with structural analysis and computation module by 100,000,000 Fiber connection; Host computer system comprises main control module, database module and fluid and structural simulation module; By main control module In-put design variate-value, constraint condition and objective function, and run Pneumatic Calculation module, structural calculation module and fluid and structural simulation module; Database module provides access interface for needing the module of accessing database, and database module comprises aerodynamic model database, structural model database and fluid structure interaction mode database.