TOPOLOGY AND VORTEX STRUCTURES OF A CURVING TURBINE CASCADE WITH TIP CLEARANCE (Ⅱ)- TOPOLOGICAL FLOW PATTERN AND VORTEX STRUCTURE IN THE TRANSVERSE SECTION OF A BLADE CASCADE

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TOPOLOGY AND VORTEX STRUCTURES OF A CURVING TURBINE CASCADE WITH TIP CLEARANCE (Ⅰ)- EXPERIMENTAL MODEL AND TOPOLOGICAL FLOW PATTERNS ON BOTH ENDWALLS AND BLADE SURFACES

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TOPOLOGY AND VORTEX STRUCTURES OF A CURVING TURBINE CASCADE WITH TIP CLEARANCE (Ⅰ)- EXPERIMENTAL MODEL AND TOPOLOGICAL FLOW PATTERNS ON BOTH ENDWALLS AND BLADE SURFACES

By means of ink trace visualization of the flows in conventional straight, positively curved and negatively curved cascades with tip clearance, and measurement of the aerodynamic parameters in the transverse section, and by appling topology theory, the structures on both endwalls and blade surfaces were analyzed. Compared with conventional straight cascade, blade positive curving eliminates the separation line of the upper passage vortex and leads the secondary vortex to change from close separation to open separation, while blade negative curving effects merely the positions of singular points and the intensities and scales of vortex. Foundation items: 973 Project of China; the Doctoral Foundation of Education Ministry of China (EDAF24403003) Biography: YANG Qing-hai (1969−)     

NOISE AT INCEPTION AND COLLAPSE OF A CAVITY

The paper analyzes the noise at inception and collapse of an isolated bubble cavityfilled with gas and vapour.The expressions and their numerical solutions of the soundpressure and the vibration velocity are presented.The results indicate that the noise occurs at every stage of a cavity.The noise hascomparatively big value only at the late period of collapse.The sound pressure is ofmagnitude 100db.     

NUMERICAL STUDY OF PARTICLE DISTRIBUTION IN WAKE OF LIQUID-PARTICLE FLOWS PAST A CIRCULAR CYLINDER USING DISCRETE VORTEX METHOD

Particle-laden water flows past a circular cylinder were numerically investigated. The discrete vortex method (DVM) was employed to evaluate the unsteady water flow fields and a Lagrangian approach was applied for tracking individual solid particles. A dispersion function was defined to represent the dispersion scale of the particle. The wake vortex patterns, the distributions and the time series of dispersion functions of particles with different Stokes numbers were obtained. Numerical results show that the particle distribution in the wake of the circular cylinder is closely related to the particle's Stokes number and the structure of wake vortices: (1) the intermediate sized particles with Stokes numbers, St, of 0.25, 1.0 and 4.0 can not enter the vortex cores and concentrate near the peripheries of the vortex structures, (2) in the circular cylinder wake, the dispersion intensity of particles decreases as St is increased from 0.25 to 4.0.     

A STUDY ON YIELD AND FLOW OF ORTHOTROPIC MATERIALS

On the assumption that the yield criterion of orthotropic materials is isomorphic withHuber-Mises criterion of isotropic materials,we put forward a dimensionless stress yieldcriterion,and obtained the associated plastic flow law.Using experimental stress-straincurves in various simple stress states,generalized effective stress-strain formulae may bederived correspondingly in various forms.     

LIE SYMMETRIES AND CONSERVED QUANTITY OF A BIPED ROBOT

I. INTRODUCTION It is well known there are close relationships between the symmetries and conservation laws inmechanical systems. The symmetric principles are among the key issues in mechanics. Two e?ectivemethods of studying the symmetries and conservation laws of mechanical are Noether’s method[1] andLie’s method. The approach to Lie symmetries was reported in the 19th century, but no applicationin mechanics appeared until 1979[2]. In recent years, studies of Lie’s method have be…     

MODEL OF CENTRIFUGAL EFFECT AND ATTITUDE MANEUVER STABILITY OF A COUPLED RIGID-FLEXIBLE SYSTEM

IntroductionThedynamicandcontrolofcoupledrigid_flexiblesystemisaleading_edgeresearchsubjectthathasdrawnextensiveattentionfromtheacademiccommunityintheworld[1].TheresearchconductedbyKaneetal.in 1 987[2 ]suggestedthat,thetraditionalmodelapplyingstructuraldynamicsassumptionaboutelasticdeformationindiscriminately[3,4 ],ineffect,hasneglectedtheso_called“dynamicstiffening”effectresultedfromcoupledrigid_flexiblesystem .Therefore ,itisofparticularimportancetoresearchtheactionofcoupledrigid_flexibles…     

REFLECTION AND RADIATION OF A WAVE SYSTEM AT THE OPEN END OF A SUBMERGED ELASTIC PIPE

The reflection and radiation of a wave system at the open end of a submerged.semi-infinite elastic pipe are studicd.This wave system consists of a flexural wave in the pipe,anacoustic surface wave in the fluid exterior to the pipe and an acoustit wave in the pipe’sinterior.Fourier transfrom techniques are used to formulate this semi-infinite geometryproblem rigorously as a Wiener-Hopf type equation.An approximate solution is obtainedby using a perturbation method in which the ratio of the massdensities of the fluid and thepipe material is regarded as a small parameter.The calculation of the reflection coefficientis emphasized,and the polar plots of the radiation coefficient are also presented.     

MAXIMAL ELEMENTS OF A FAMILY OF GB-MAJORIZED MAPPINGS IN PRODUCT FC-SPACES AND APPLICATIONS

A new family of GB-majorized mappings from a topological space into a finite continuous topological spaces （in short, FC-space） involving a better admissible set-valued mapping is introduced. Some existence theorems of maximal elements for the family of GB-majorized mappings are proved under noncompact setting of product FCspaces. Some applications to fixed point and system of minimax inequalities are given in product FC-spaces. These theorems improve, unify and generalize many important results in recent literature.     

THE BOUNDED SOLUTION OF A CLASS OF DIFFERENTIAL-DIFFERENCE EQUATION OF ADVANCED TYPE AND ITS ASYMPTOTIC BEHAVIOR

In this paper, we consider the differential-difference equation of advanced type with perturbation term. It is shown that if the bounded solution of the reduced equation has negative exponential order and the perturbation term f satisfies certain condition, then the bounded solution of the perturbation equation has negative exponential order.     

LAGRANGE'S THEOREM FOR A CLASS OF NONHOLONOMICSYSTEMS AND ITS APPLICATION

I.IntroductionSinceE.T.Whittaker.proposedfoestabilit}'problellll'lofnonholononlicsystemsin1904forthefirsttime,thescholarsathomeandabroad11a\'emadealotofresearchesontheequilibriunlstabilityoflinearand11olllinearnonllolollolnicsystems,andhaveobtainedaseriesofimportantresultslZ--7].Hobbled'er,theexpositionandapplicationrelatedtoLagrange'stheorenlinthestabilityanalysisfornonholonomicsystemsisseldonlseenuptonow.Althoughitwasmentionedinreference[3].aspecialdiscussionhasnotbeencarriedoutyet.Asafam…     

TRANSMISSION AND DIFFRACTION PATTERN BY A MONOLAYER OF OPAQUE SPHERES

Transmission and diffraction of radiation through a monolayer of monodisperse opaque spherical particles at different particle concentrations are studied theoretically and by numerical calculation. It is found that the transmission and the diffraction pattern are strongly dependent on the receiving aperture and the monolayer density.     

THE CALCULATION OF BENDING AND STABILITY OF A THIN RECTANGULAR PLATE FOR VARIABLE RIGIDITY

The subject discussed in this paper is the rectangular plate.Its two opposite edges are simply supported,while the othertwo are arbitrary,and the rigidity of the plate is variablealong the direction parallel to the simply supported edges.In order to solve the problem,the author adopts the finiteplate-strip element method,which is different from theusual finite element method or the finite strip method.Thesteps of the above method is no longer to establish a rigidi-ty matrix for elements or strips and gather them into a totalmatrix for solution.Now the relation of transfer betweenthe strain and inner force of every plate-strip is shown.Fi-nally a practical example is given and this method is foundto be easier and more effective.     

SOME THEOREMS FOR DETERMINING THE DEFINITENESS AND CHANGEABILITY OF SIGN OF FUNCTIONS AND THE APPLICATION TO THE CONDITIONAL STABILITY OF THE MOTION OF THE AXIS OF A SLEEPING TOP

This paper gives some theorems for determiningthe definiteness and changeabilitg of sign of func-tions as well as the application to the axis of asleeping top.The necessarg and sufficient condi-tion of the conditional stabilitg of the rotion isobtained.Which coincides With that.of the stabilitgof nutation angle and also with that of the stabili-ty of total variables in the equations of cotion.     

A METHOD OF FINDING THE PRINCIPAL MODES OF NONLINEAR VIBRATION SYSTEMS AND THEIR STABILITIES

This paper presents a new method of finding the principal modes of nonlinear vibrationsystems,by means of which the problem of finding principal modes of nonlinear systems istransferred to the problem of finding real roots of a set of algebraic equations.The methodis applicable to various kinds of nonlinear vibration systems with many degrees of freedom,and is simple in calculation.The paper presents another new method of analyzing thestabilities of principal modes of nonlinear systems.     

ON THE STRUCTURE OF CONTINUA AND THE MATHEMATICAL PROPERTIES OF ALGEBRAIC ELASTODYNAMIC OF A TRICLINIC STRUCTURAL SYSTEM

This paper is neither laudatory nor derogatory but it simply contrasts with what mightbe called elastostatic(or static topology),a proposition of the famous six equations.Theextension strains and the shearing strainsfor all i,j,k=1,2,3.which were derived by A.L.Cauchy,are linearly expressed in terms of nine partialderivatives of the displacement function(u_i,u_j,u_k)(?)u(x~i,x~j,x~k)and it is impossiblefor the inverse proposition to sep up a system of the above six equations in expressing thenine components of matrix((?)(u_i,u_j,u_k)/(?)(x~i,x~j,x~k)).This is due to the fact that ourgeometrical representations of deformation at a given point are as yet incomplete .On theother hand,in more geometrical language this theorem is not true to any triangle,exceptorthogonal,for“squared length”in space.The purpose of this paper is to describe some mathematic laws of algebraicelastodynamics and the relationships between the above-mentioned important questions.     

INTERACTION BETWEEN A SCREW DISLOCATION AND A PLASTIC ZONE OF AN ARBITRARY SHAPE

A plastic deformation zone near a screw dislocation is treated as an equivalent trans- formation inclusion by means of the Eshelby inclusion theory.A closed-form solution for deter- mining the interaction between a screw dislocation and a plastically deformed zone of an arbitrary shape is obtained by using the solution between a dislocation and an equivalent transformation inclusion.