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2011 Vol. 43, No. 3

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Numerical investigation of self-aligning spiked bodies at hypersonic speeds
Geng Yunfei Chao Yan
The conventional fixed spike method, in which the spike is mounted with an alignment along the body-axis, always failed at relatively high angles of attack; therefore, a new self-aligning spike method is investigated in the present paper. This method is applied to 3D axi-symmetrical blunt cone and compressed wedge configurations at hypersonic speeds. Numerical simulations are carried out to verify this new concept. Spiked geometries with different L/D parameters at angle of attack ranged from 0 to 12 degrees are investigated. Numerical results reveal that the self-aligning spike method has great capability in drag and heat reduction as compared with the conventional fixed spikes. It can still effectively work even at relatively large angles of attack. This new method can resolve the problem that encountered by the conventional spike method.
2011, 43(3): 441-446. doi: 10.6052/0459-1879-2011-3-lxxb2010-732
The study on micro-scale particle coagulation due to turbulent shear mechanism using TEMOM model
Yu Mingzhou Jiang Ying Zhang Kai
The coagulation due to turbulent shear is the mainmechanism leading to the instability of micro- and nanoparticle-ladenmultiphase flows. The Smoluchowski mean-filed theory is considered to be agood selection for solving this problem since it can be coupled to someturbulent models. In this study, the Taylor-expansion method of moments(TEMOM) is first applied in micro- and nanoparticle coagulation due toturbulent shear mechanism in which the closure of Smoluchowski equation aswell as the relationship between the numerical accuracy and the order ofTaylor series expansion are emphatically investigated. The result show thepartial 4-order Taylor expansion method of moments can be applied to analyzethe problem involving micro- and nanoparticle turbulent shear coagulationwith high accuracy, and the pseudo self-preserving size distribution isfound in micro- and nanoparticle-laden multiphase systems dominated byturbulent shear mechanism.
2011, 43(3): 447-453. doi: 10.6052/0459-1879-2011-3-lxxb2010-115
Numerical research on the interaction between ionized gas and magnetic field under high hall parameter
Hu Haiyang Yang Yunjun Zhou Weijiang
By coupling Poisson's equation for the electric potentialfield with flow-field N-S equations through Lorentz force and the jouleheat, numerical simulation of magneto-fluid with low magnetic Reynoldsnumber was carried out. The influence of the Hall effect and the externalcircuit was considered. The Poisson's equation ill-conditioned matrix causedby high Hall parameter was overcomed by LUSGS pretreatment BI-CGSTABalgorithm without pseudo time step. Numerical simulations of two kind ofphenomenon, hypersonic magneto-fluid flow around a circular cylinder whenHall parameter reaching about 10$^2$ and the energy deposition in scramjetisolator, indicate that external circuit, electrode cooling measures andplasma uniformity have great influence on the electro-magnetic force.
2011, 43(3): 453-460. doi: 10.6052/0459-1879-2011-3-lxxb2010-287
Breakdown of locally heated and subcooled laminar films with interfacial shear
Ye Xuemin Li Chunxi Yan Weiping
The theoretical models of critical film thickness andminimum wetting rate were established for locally heated and subcooledlaminar films under different flow directions of gas and liquid, and theeffects of the contact angle, film temperature, interfacial shear and heatflux were discussed driving by gravity or/and interfacial shear. Theinvestigation shows that the critical film thickness and minimum wettingrate increase with increasing heat flux. The effect of contact angle isclearly different in different range of heat flux under gravity driving, andthe film temperature has a contrary influence on minimum wetting ratedriving by gravity and interfacial shear. The critical film thickness andminimum wetting rate decrease with cocurrent shear. Under the combination ofgravity and interfacial shear, the effect of cocurrent shear on minimumwetting rate is closely related with the ratio of gravity to shear, and theincreasing countercurrent shear leads the critical film thickness andminimum wetting rate to decrease.
2011, 43(3): 461-467. doi: 10.6052/0459-1879-2011-3-lxxb2009-673
Numerical simulation of the severe slug flow between water-air phases in a declination pipe-riser
Gao Song You Yunxiaing Li Wei Hu Tianqun Yu Zhong
In the present paper, a numerical method for simulatingthe characteristics of two-phase flows in a declination pipe-riser systemwith the gas and fluid was developed. The Brackbill modelwas applied to simulate surface tension between two phases and the VOF method was used to capture themoving interfaces between gas-liquid phases. At low superfical velocity of gas and liquidsuperficial velocities, severe slug flows in such a pipe-riser system weresimulated and the variety characteristics for flow parameters were analyzed.The results show that the flow parameter characteristics due to such asevere slug flow have remarkably periodic characteristics, including theflow pattern, pressure, slug velocity, average phase velocity at the riseroutlet and gas volume fraction, and severe slug flow in a period consists offour evolvement stages where the characteristics of such flow parameters ineach evolvement stage were further given. The numerical results are goodagreements with experimental results reported in the references, showingthat the proposed method is effective.
2011, 43(3): 468-475. doi: 10.6052/0459-1879-2011-3-lxxb2009-675
A study of sediment transport modele in one-dimensional numerical channel network model
Han Dong Fang Hongwei Chen Minghong He Jianguo Bai Jing
Hydrodynamics and sediment transport model are generallyused to simulate the evolution of natural alluvial rivers. In this paper, anexplicit recursive method for sediment transport in channel network ispresented. Based on hydrodynamic calculation, the method can be used todirectly calculate non-equilibrium sediment transport process, involvingsuspended load and bed-load gradation adjustments one by one node in eachriver. This method avoids solving the matrix of the relationship betweenfirst and last sections, which is popular in traditional methods. Aone-dimensional mathematical model with the sediment transport method isapplied to the Jingjiang River-Dongting Lake region in the Three GorgesProject. Results are greatly in accord with the actual measurement.Computation cost is reduced and high accuracy is obtained in the new method.Moreover, the differences among different models of suspended load diversionin the node are discussed in the paper.
2011, 43(3): 476-481. doi: 10.6052/0459-1879-2011-3-lxxb2010-384
Research on the deposition efficiency of nanoparticle in human nasal cavity
Zhao Xiaodong Zhang Kai Tian Fuzhen
The Eulerian and Lagrangian method are used tonumerically simulate the transport and deposition of nanoparticle in humannasal cavity with finite volume method. The k-w turbulence model is used toget the flow field, and one-way coupling Lagrangian method is used to trackthe trajectory of nanoparticle with Stokes, Brownian and thermophoreticforce considered in this model. It's found that Deposition in the nasalcavity is high for very small nanoparticles. The particle diameter range inwhich the deposition drops from 80% to 18% is between 1,nm and 10,nm.From 10,nm to 150,nm however, there is only a small change in the depositioncurve from 18% to 5%. These results are helpful to develop themedicine the disease of human nasal cavity.
2011, 43(3): 482-487. doi: 10.6052/0459-1879-2011-3-lxxb2010-512
Parametric variational principle and numerical algorithm for LQ optimal control with constrained control input
Peng Haijun Gao Qiang Zhang Hong-Wu Wu Zhigang Zhong Wanxie
Based on the theory of analogy, the parametricvariational principle derived from plastic mechanics and contact mechanicsis developed and applied to the theory of optimal control. New coupledequations of Hamilton canonical equation and linear complementarity equationare established for the problem of LQ optimal control with constrainedcontrol input. By dividing the continuous time into a series of equidistantintervals, a new numerical algorithm based on the parametric quadraticprogramming method for solving the coupled-equations is proposed in thediscrete time domain. Numerical simulations show that the algorithm given inthis paper is effective for the problem of LQ optimal control withconstrained control input and the convergence speed and accuracy of thealgorithm is satisfactory.
2011, 43(3): 488-495. doi: 10.6052/0459-1879-2011-3-lxxb2010-465
Collocation interval finite element method
Qiu Zhiping Qi Wuchao
Based on shortcoming analysis of `point approximation'interval finite element method with Taylor expansion, collocation intervalfinite element method based on the first Chebyshev polynomials which canapproach objective function in global domain is proposed in this paper. Themethod does not require the sensitivities of the objective function withrespect to uncertain variables and the assumption of narrow interval is alsonot needed. The method is suitable for solving the case that the objectivefunction is strongly nonlinear with respect to the uncertain variables. Theorthogonal expansion coefficients of the objective function are obtainedfrom Gauss-Chebyshev quadrature formula. So Gauss integration points arecollocated in the intervals of uncertain variables. The main computationaleffort is to calculate the values of objective function at Gaussianintegration points. When the number of the uncertain variables is $m$ and theten-point Gauss integral method is introduced, it is needed to analyze thesystem with 12m times. Examples show that the collocation interval finiteelement method can still obtain almost exact interval bounds in the casethat other interval finite element methods are invalid.
2011, 43(3): 496-504. doi: 10.6052/0459-1879-2011-3-lxxb2010-382
Stochastic harmonic function and spectral representations
Chen Jianbin Li Jie
Stochastic harmonic function representations and their properties are studied. In thepaper, it is firstly proved that as the distributions of the random frequencies are consistent with thetarget power spectral density function, the power spectral density of the stochastic harmonicprocess is identical to the target power spectral density. Further, it is proved that the stochasticharmonic process is asymptotically normally distributed. The rate of approaching normaldistribution is discussed by adopting Pearson distribution to describe the one-dimensionaldistribution of the stochastic harmonic process. Compared to existing representations of stochasticprocess, very few stochastic harmonic components can capture the exact target power spectraldensity. This greatly reduces the number of the random variables and thus eases the difficulty ofstochastic dynamics. Finally, linear and nonlinear responses of a multi-degree-of-freedom systemsubjected to random ground motions are carried out to exemplify the effectiveness and advantagesof the stochastic harmonic representations.Keywords: Stochastic harmonic function, power spectral density function, covariance function,stationary process, nonlinearity
2011, 43(3): 505-513. doi: 10.6052/0459-1879-2011-3-lxxb2010-375
Analysis of equivalent elastic modulus of a honeycomb sandwich
Chen Daiheng Yang Lu
In this paper, in-plane equivalent elastic modulus of ahoneycomb sandwich, consisting of hexagonal cell core and face sheet, isstudied by using a theoretical analysis. It is shown that the equivalentelastic modulus can not been analyzed with high precision by treating thehoneycomb as a composite of two materials: the core and the face sheet,because the core consists of portions of the slanting cell walls and thevertical cell walls, whose rigidities differ greatly. Dividing the core intothe slanting cell wall portion and the vertical cell wall portion, andregarding the honeycomb as a composite of three materials, a method tocalculate elastic modulus is proposed based on the principle of the minimumpotential energy, and its validity is verified by numerical results of FEM.
2011, 43(3): 514-522. doi: 10.6052/0459-1879-2011-3-lxxb2010-113
Ratcheting study of pressurized lateral nozzle of cylinder
Yang Lidong Dong Junhua Gao Bingjun
Lateral nozzle of cylinder or lateral tee piping is widely used in nuclear,electric, petroleum and chemical industries. The cylinder or the piping maysuffer plastic accumulation, namely ratcheting, due to fluid pressuretogether with seismic load and thermal expansion. Extensive and quantitativeratcheting investigation is necessary to detemine the ratcheting boundaryfor the safety of the structure. As the phenomenological cyclic plasticconstitutive models have made a great progress in the last two decades, someinvestigators have taken advantage of the advanced model to evaluate theratcheting of simple structure of pressure vessels and piping. However, fewliterature studied ratcheting and ratcheting boundary of complicatedstrctures such as lateral nozzle of cylinder or lateral tee piping.In this paper, ratcheting of pressurized lateral nozzle of cylinder made of20$^{\#}$ carbon steel was experimentally studied with a multiaxial fatiguetesting system and a self-designed in-plane bending apparatus for lateralnozzle structure. The specimen, pressurized by a pumping station withadjustable pressure, was simply supported on a stiff beam, and pulled in apulsatile way by the servo-hydraulic testing machine to simulate thein-plane cyclic bending. Ratcheting strains were acquired by multi-channelstrain processors with strain gauges. The cyclic loading and the strainacquirement were controlled and processed simutaneously by a computer.Ratcheting strains were detected around the acute angle region of thestructure. It was found that ratcheting mainly occured in the direction ofthe first principle strain, which is directed to the intersecting weld. Themaximum ratcheting strain occured at the nozzle side of the acute angleregion in the symmetrical plane for the structue. Ratcheting boundaries ofgauged points were experimentally determined by step pressure loading.Numerical ratcheting analysis of structure was accomplished by secondarydevelopment of ANSYS with four typical kinematic hardening models, in whichOhno-Wang model and its modified models improved the prediction ofratcheting strain. Ratcheting boundaries of gauged points were numericallydetermined by the equivalent plastic strain increment control method withMJS model(Modifed Jiang-Sehitoglu model) and validated to be in goodagreement with that experimental results. Finally, the ratcheting boundaryof the structure was determined according to the values of maximumratcheting strain point, which may be used to evaluate the shakedown of thestructure.
2011, 43(3): 523-532. doi: 10.6052/0459-1879-2011-3-lxxb2009-698
The Green's function solution of Lamb's problem for a saturated porous medium
Ding Boyang Chen Jun Pan Xiaodong
At the beginning of last century, Lamb obtained thedisplacement solutions of a wave field on the semi-infinite space subjectedto a concentrated force. These solutions are widely applied in soildynamics, seismic engineering and geophysics. Lamb's achievements are stillbeing regarded as an important tool to solve the response and vibrationproblems in current research and engineering. However, it should be notedthat Lamb's solutions only satisfy a homogeneous single medium. There aremany dynamic problems of the multi-phase or saturated porous medium inpractice. Thus, scientists and technicians have been concerned with thedisplacement solutions to a semi-infinite space of a saturated porous mediumsubjected to a concentrated force. Philippacopoulos obtained the solutions onthe semi-infinite space of a saturated porous medium subjected to aconcentrated force in 1987. This step occurred for 73 years after Lambfinished the above-mentioned work, then 25 years after that Biot put forwarda dynamics equation of a saturated porous medium. It is the mathematicaldifficulty that inhibits the development, and the most distinct difficultyis the coupling of fast and slow dilational waves in the dynamic equation ofa saturated porous medium. Philippacopoulos have not solved the couplingproblem. His solutions are gained with a corresponding determinant of Eigenequations, which equals to zero, so that the solutions are complex and thededuction is complicated. The loads applied to a saturated porous mediumhave been varied such as the moving, the torsions, the swing and so on. Atthis stage we should decouple the fast and slow dilational waves forregularization of solving the dynamics problem of a saturate porous medium.Based on the Homholtz's solution for the Biot dynamics equation of asaturated porous medium with complex-coefficient and Fourier transformation,especially, according to the reverse of the fast and slow dilational waveson vibration phase, the authors solved the coupling of the fast and slowdilational waves and obtained Green's function to the dynamics equation of asaturated porous medium in 1999. These results are consistent with Chen'sresults (1994) which were obtained by referring to the continuity of thesolution to the dynamics equation with an inhomogeneous term $\delta $function and the discontinuity of its first order derivative. Utilizing theGreen functions and its transformation form in axisymmetric cylindricalcoordinates, using Sommerfeld's integral and the influence of a free surfacefield, the authors obtained the dynamic displacement solutions of asaturated porous medium subjected to a concentrated force in thesemi-infinite space. Naturally, the solutions are consistent with thePhilippacopoulos's solutions. When a saturated porous medium decays asingle-phase medium, the results are consistent with Lamb's results. Thewhole process of deduction is common with a clear physical meaning. Hence,it not only justifies the method of solving (by means of) a coupling of fastand slow dilational waves of a saturated porous medium in this paper, italso provides reference to regularization and generalization for solving thedynamics problem in the semi-infinite space of a saturated porous medium.
2011, 43(3): 533-541. doi: 10.6052/0459-1879-2011-3-lxxb2010-090
Simulation and comparison of different dynamical models of space webs
Li Jingyang Yu Yang Hexi Baoyin Junfeng Li
Space webs which have great potential applications inorbit Service, recovery of spacecraft, orbit cleaning, space interceptor,woven from lightweight and pliable rope, are webs of unstable configurationformed by throwing and spreading. This paper adopts the finite elementsoftware ABAQUS in order to model the system of elastic webs and the systemof flexible webs, compares the projecting of two finite element models,proposes metrics on the deployable of webs' system and focuses on tractionmass, projectile point, projectile velocity of webs and equivalent dampingeffect of ropes on webs' deployable under a variety of different conditions.The results of simulation indicate that the unfolding effect of flexiblewebs is better than that of the elastic webs; traction mass, projectilevelocity of webs and equivalent damping effect of ropes are the key factorsin effectively webs' unfolding, and projectile point is the main factor todecide the unfolding area to the predetermined location.
2011, 43(3): 542-550. doi: 10.6052/0459-1879-2011-3-lxxb2010-390
On the moment lyapunov exponent of a viscoelastic plate subjected to the excitation of wide band noises
Huang Yong Li Shenghong Liu Xianbin
In the present paper, the moment Lyapunov exponent of aviscoelastic plate in a supersonic gas flow subjected to the excitation ofwide band noises is investigated. A aeroelastic model for two coupleddegrees-of-freedom panel is established by using the Von Karman platestheory, the quasi-first-order piston theory and Galerkin approximation. Viathe stochastic averaging method, the four-dimensional system is reduced to atwo-dimensional one. Through the logarithmic polar transformation , and thenGirsanov theorem and Feynmann-Kac formula, the backward differentialoperator is then obtained. By expanding the eigenfunctions as a Fouriercosine series, the approximate analytic expansion of the moment Lyapunovexponent is then obtained and matched by the Monte Carle simulation results.Finally, the influences of the system parameters, gas dynamical parametersand the spectral density of noises on the stochastic stability ofviscoelastic plate is studied.
2011, 43(3): 551-560. doi: 10.6052/0459-1879-2011-3-lxxb2009-776
Vibration analysis of cylindrical helical springs considering warping deformation effect
Hao Ying Yu Aimin
The free vibrational behavior of cylindrical helicalsprings with rectangular cross sections is analytically investigated in thispaper based on spatial curved beam theory. In the differential equations ofmotion of the springs, all displacement functions and a generalized warpingcoordinate are defined at the centroid principal axes and the warping effectupon the natural frequencies is also considered in present study. Explicitanalytical expressions which give the vibrating mode shapes are derived byrigorous application of the symbolic computing package MATHEMATICA and aprocess of searching is used to determine the exact natural frequencies.Numerical examples are provided for the springs with the rectangularcross-section and clamped-clamped and clamped-free boundary conditions. Thefree vibrational parameters are chosen as the ratio of the width to height(a / b = 0.6 - 1.7) for a rectangular cross section, the number of activeturns (n = 6 - 12), the helix pitch angle (\bar {\alpha } = 5 - 12.5^\circ ) and the radial of cylinder (R = 4 - 10mm) in a wide range.Validation of the proposed model has been achieved through comparison with afinite element model using three-dimensional solid elements (Solid 45) andthe available literature, showing a good agreement among them.
2011, 43(3): 561-569. doi: 10.6052/0459-1879-2011-3-lxxb2010-101
Frictional contact analysis of spatial prismatic joints in multibody systems
Qi Zhaohui Luo Xiaoming Huang Zhihao
In traditional methods, the details of relative motionbetween two bodies is necessary to locate contact points. When they areapplied to analyze the contact in a joint, the bodies linked by the jointmust be taken as free, no matter how small the clearance of the joint is. Asa result, such drawback makes numerical solution inefficient and inaccuratein some cases. It is found that, the system of contact forces in a joint andthe system of constraint reaction forces of the joint are equivalent, andthe motion of possible contact points in joint relate each other inherently.Based on these facts, this paper present a method for frictional contactanalysis of spatial prismatic joints, by which the positions and forces ofcontacts can be obtained while the kinematic constraints of prismatic jointsare kept. Numerical examples prove the validity of the method.
2011, 43(3): 570-578. doi: 10.6052/0459-1879-2011-3-lxxb2009-669
The iterative digraph cell mapping method of non-smooth dynamical systems
Li Shuang He Qun
Digraph cell mapping method (DCMM) is an effectivetechnique to analyze the global behavior of dynamical systems. Recently, ithas been applied to the study of crises and stochastic bifurcation, whichachieved a series of good results. However, many researches by DCMM arebased on smooth dynamical systems, and it is unknown whether this method canbe applied to non-smooth systems. In this paper, the key problem namedexpansion of cell flow is discussed in detail when the digraph cell mappingmethod is applied to analyze non-smooth dynamical systems. It is found thatbecause of non-smooth boundary the expansion of cell flow is usuallyserious, which may result in analysis distortion of DCMM. For the aboveproblem, the notion of the artificial node set is introduced to record whichstate cells may cause the expansion of cell flow. Taking the artificial nodeset as the redivided object, an iterative version of DCMM together with itseffective algorithm is designed to decrease the expansion of cell flow andimprove the computing accuracy. Furthermore some remarks are suggested forreaders to analyze complex non-smooth systems. In the iterative processes,the present method can not only keep the integrality of all computingresults but also significantly enhance the computing efficiency. As anillustrative example, the Duffing-van der Pol vibro-impact system withcomplex nonlinear structures is taken to demonstrate the validity of theproposed method.
2011, 43(3): 579-585. doi: 10.6052/0459-1879-2011-3-lxxb2010-042
Research of the dynamic experimental modeling for viscoelastic composite beam
Wu Jian Ye Min Li Xing Dou Suguang
The viscoelastic materials are used widely with thedevelopment of new materials, and the nonlinear dynamic behavior inviscoelastic composite structure is becoming increasingly outstanding andimportant. The main purpose of this paper is a study of some nonlineardynamic problems of viscoelastic composite structure under parametricexcitation by using the experimental modeling method. The dynamic modelingmethod based on the theory analysis increases the difficulty on account ofthe complexity of the constitutive relation of viscoelastic materials. So itis one of the important means in the construction of dynamic model tocombine theory with experiment. The establishment of the experimental modelcorresponding to the theoretical model and the related identification theoryof nonlinearity system must be considered in the experimental modeling.A series of composite material samples are synthesized by using ABS(acrylonitrile-bu- tadine-styrene copolymer) resin as basic material andadding rutile nanoscaled titania from 1% to 10% as reinforcedmaterial. The experiment platform of the nonlinear parametric excitationvibration system is set up. The vibration is investigated for thenanocomposites beam with one end pinned and the other movable support, whenaxial excitation and controlled Drp-frictional forces are applied. By takingthe experimental modeling method and applying to the Incremental HarmonicBalance Nonlinearity Identification, the dynamical equation of theviscoelastic composite beam is then built. Based on numerical simulation,comparisons between theoretical model and experimental system show goodagreement in qualitative and quantitative analysis. The theoretical model isapplicable for a class of composite materials with different weight ratiosof reinforced material and matrix.
2011, 43(3): 586-597. doi: 10.6052/0459-1879-2011-3-lxxb2010-326
Moving mass identification of vehicle-bridge coupled system based on virtual distortion method
Zhang Qingxia Duan Zhongzheng Jankowski Lukasz
In the inverse analysis of vehicle-bridge coupled system,moving vehicle (load) identification is a crucial problem. Traditionallymoving vehicles are identified by identifying the equivalent moving forces,which is a well-known ill-conditioning problem, and hence is sensitive tonoise. Moreover identification of moving forces require the number ofsensors equal to or bigger than the number of unknown forces to obtain theunique solution. In order to avoid these drawbacks, this paper presents aneffective method to identify moving vehicles. Vehicle parameters are chosenas the variables, which are optimized by minimizing the square distancebetween the measured structural responses and estimated responses. Duringthe optimization, the computational work is reduced a lot by the proposedconcepts of dynamic moving influence matrix based on Virtual DistortionMethod (VDM), which consists of impulse response matrix with respect to thechanging positions of the moving masses and is independent of mass values,and only needs to be computed once in advance. In this way, the repeatedlyconstruction of the variant system matrix is avoided, and hence theoptimization efficiency is improved. In this method, a mass-spring dampingmodel with two degree of freedoms (Dofs) is used to simulate moving vehicleand its dynamic behavior. Moving vehicles and the bridge are analyzed asdifferent substructures. In addition the equivalent moving loads arereconstructed simultaneously, such that the well-conditioning of theidentification is ensured and makes the method be accurate and robust tonoise. Moreover the number of the necessary sensors is decreased. Thenumerical costs are considerably reduced further by using the concepts ofVDM, which belongs to fast reanalysis method, that is, the response of themodified structure equals to the response of an intact structure subjectedto the same external load and to certain virtual distortions which model thechanges of the actual structure. In this way, during the optimization, thestructural response under given optimization variables are estimated quicklywithout the whole analysis of the global structure. Numerical experiment ofa frame beam with 5{\%} Gaussian measurement error is used to verify theproposed method, where the effectiveness of different simplified vehiclemodels is compared. It demonstrates that masses of multiple moving vehiclescan be identified using fewer sensors. When the roughness of road surface isneglected, under normal speed, the structural response is mainly caused bythe weight of vehicles, and the coupling between the vehicle and bridge israther low, therefore the influence of the vehicle spring stiffness anddamping is very weak on the mass identification. For the identification ofmultiple vehicles, masses of the mass-spring damping model with two Dofs canbe identified satisfactorily with the stiffness and damping as the estimatedinitial values. The identification considering the road roughness or highspeed using the proposed method in this paper is undergoing.
2011, 43(3): 598-610. doi: 10.6052/0459-1879-2011-3-lxxb2009-481
Multi objective optimization methodology for airfoil robust design under geometry uncertainty
Li Jiaozan Gao Zhenghong
Traditionally, aerodynamic shape optimization has focusedon obtaining the best design given the requirements and flow conditions.However, the manufacturing accuracy of the optimal shape is depends on theavailable manufacturing technology and other factors, such as manufacturingcost. It is imperative that the performance of the optimal design isretained when the component shape differs from the optimal shape due tomanufacturing tolerances and normal wear and tear. These requirementsnaturally lead to the idea of robust optimal design wherein the concept ofrobustness to various perturbations is built into the design optimizationprocedure. Here we demonstrate how both multi-objective evolutionaryalgorithm and surrogate model can be used to achieve robust optimal designs.Test cases include the deterministic optimization and robust design ofairfoils, and the results were compared. It was shown that the presentrobust aerodynamic shape optimization method is a useful tool to design themore practical airfoil for air vehicles.
2011, 43(3): 611-615. doi: 10.6052/0459-1879-2011-3-lxxb2010-066
Moving-particle semi-implicit method research based on large eddy simulation
Pan Xujie Zhang Huaixin Sun Xueyao
The moving-particle semi-implicit method (MPS), coupledwith a large eddy simulation (LES), is presented to free surface problem forturbulent flow. The control equation for LES is derived though the filteringoperation of the Navier-Stokers equation. In the control equation,additional Reynolds stress terms are only different between LES and MPS.Therefore MPS is extended to LES by coupled with a sub-particle-scale (SPS)turbulence model and the Smagorinsky model which is able to describe theReynolds stress terms. The MPS-LES method is used in the case of simulationof resonance sloshing, and the simulation result is very close to that ofexperiment or other numerical simulation.
2011, 43(3): 616-620. doi: 10.6052/0459-1879-2011-3-lxxb2010-403
High-order discontinuous galerkin solution of linearized Euler equations
Lu Hongqiang Zhu Guoxiang Song Jiangyong Wu Yizhao
In this paper, the linearized Euler equations (LEE) foraero-acoustics are solved using high-order Discontinuous Galerkin (DG) onunstructured grid for complex geometries. The background field, calculatedusing Finite Volume Method on structured grid, is first transferred into theLEE grid with a highly accurate method . A straightforward quadrature-freeimplementation method and parallel computing are used to accelerate thecomputation. Numerical tests indicate that very detailed features can beresolved even though high order DG was used on very coarse grids.
2011, 43(3): 621-624. doi: 10.6052/0459-1879-2011-3-lxxb2010-077
The structure analysis about the cavitation flow around the cascade hydrofoil by numerical and experimental study
Shi Suguo Wang Guoyu Huang Biao
The unsteady dynamics of cavitating flows around ahydrofoil and in a cascade hydrofoil are investigated by numerical andexperimental methods. Experiments around a hydrofoil and on a cascadehydrofoil are carried out in a rectangular test section of a cavitationtunnel,and the lift and drag force are conducted and the frequencycharacteristics of lift signals are analyzed. The cavitation model incalculation is Kubota model which can describe the unsteady vortexcavitation accurately; the filter-based turbulence model can capture theunsteady characteristics in the flow more exactly; the reliability of thenumerical model is validated by the experiment of the cavitation tunnel. Theresults show that a good agreement is obtained between the experimental dataand the numerical simulation results. Compared the results around ahydrofoil, the cavitation thickness about the cascade hydrofoil is thinner;the adverse pressure gradient near the wall of the cascade hydrofoil issmaller; the intensity of the re-entrant jet and the velocity gradient inthe mixing field are smaller and the shedding time is longer.
2011, 43(3): 625-629. doi: 10.6052/0459-1879-2011-3-lxxb2010-427
Thermoelastic behavior of interface of composite plate under thermal shock
Xiong Qilin Xiao-geng Tian Shen Yapeng Xia Ronghou
Based on the generalized thermoelasticity with twothermal relaxation times (G-L theory), the mechanical parameters through thezero-impedance interface in a laminated plate under transient thermal shock,such as the displacement, stress and temperature, are studied by using thefinite element method. The displacement, stress and temperature near theinterface of the composite plate are obtained. With the influence ofspecific heat capacities, heat conduction coefficients, thermal relaxationtime and densities of two materials, it is found that the displacement andstress through the interface of composite plate has a sudden change. Theresults are useful to obtain the deflection of composite plate caused byheat.
2011, 43(3): 630-634. doi: 10.6052/0459-1879-2011-3-lxxb2010-284
Dynamic characteristics of spinning Rayleigh beams
Qian Xin Du Xingwen
This paper derives the motion equations of the spinningRayleigh beam under gravitation using the extended Hamilton principle andinvestigates the dynamic characteristics of spinning Rayleigh beam under ahinged-hinged boundary condition. The present equations show that animportant gyroscopic term induced by centrifugal force is missing in similarequations in the literature, but this term is indispensable in the modelingand analysis of spinning beams. The influences of rotary inertia, spinningspeed, gyroscopic effects, slenderness ratio on whirling frequencies,whirling modes and critical speeds are investigated in detail usinganalytical and numerical methods. The results show that the forward whirlingspeed increases up to the critical speed, and then decreases with thespinning speed; the corresponding backward whirling speed decreases thespinning speed. Each forward whirling speed is higher than the correspondingbackward whirling speed. For a spinning Rayleigh beam, there areinfinite-dimensional forward and backward critical speeds.
2011, 43(3): 635-640. doi: 10.6052/0459-1879-2011-3-lxxb2009-712