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中文核心期刊

1994 Vol. 26, No. 5

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NUMERICAL SIMULATION OF 3-D HYPEKSONIC FLOW AND NEAR WAKE AROUND BE-ENTBY VEHICLE
The knowledge of complex three-dimehsional hypersonic visous flow over re-entry bodies is of great importance in the preliminary design of atmospheric re-entry vehicles.The thin-layer Navier-Stokes equations are solved with Harte-Yee's second-order TVD fiuitedifference scheme for three-dimensional hypersonic flowfields over a re-entry vehicle, whereM_∞ =7.35,Re_∞=7.5×10 ̄5,α=10°,20°。The detailed flowfield structures are given.The pressure distributions along body surface at various angles of attack are compa...
1994, 26(5): 513-520. doi: 10.6052/0459-1879-1994-5-1995-576
THE EFFECTS OF EXTERNAL EXCITATION ON DEPARATED SHEAR LAYER
An experimental research about the effects of external excitation on shearlayer bounding the reverse flow region was carried out.The model is a sharp leading-edgewedge like model with oscillating flap, The experimental Reynolds number is 6.67×10 ̄5。The inherent character of the evolution of peak frequency in shear layer bounding reverseregion for the casses with and without excitation is revealed.The response of local shearlayer to excitation is studied. The main function of excitation are to change the evol...
1994, 26(5): 521-529. doi: 10.6052/0459-1879-1994-5-1995-577
A NEW REGION-SPLIT METHOD
A new region-split method is established on the basis of the characteristicdirection method, which is easy to be implemented on the barotropic shallow water modelwhose region is the Sphere or Hemisphere. This method has three advantages. First,theboundary conditions on the common boundary of the split regions need no special treatment.because the boundaries of the split regions can tally naturally on the common boundaryNext,using the natural periodic boundary condition along the meridional direction in then...
1994, 26(5): 530-535. doi: 10.6052/0459-1879-1994-5-1995-578
THE DISCUSSION ON MECHANISM OF BAND-EMERGING OF STRANGE ATTRACTOR
Based on the geometric structure of strange attractor which has been suggestedin[1], the mechanism of band-emerging of strange attractor is discussed,and the criterionproducing band-emerging of strange attractor is obtained.As an example. Henon map isused to illustrate t hat the mechanism is reasonable
1994, 26(5): 535-540. doi: 10.6052/0459-1879-1994-5-1995-579
STIFNESS AND STRENGTH OF ELASTIC MATRIX WITH MISORIENTED MICROCRACKS AND PROLATE SPHEROIDS
In This paper,a new andytical model is used to study the influence of misorientedmicrocracks on stiffness and strength of prolate spe roid-rei nforced composite material witheighst rain. The interaction b etween microcracks and prolate spheroids is analysed usingequlvalent inclusion method and the stress field, constitutive relation and the critical failurecondition are given.
1994, 26(5): 541-550. doi: 10.6052/0459-1879-1994-5-1995-580
THE DYNAMIC RESPONSE OF THE CRACK IN THE INTERFACE BETWEEN TWO DISSIMILAR ORTHOTROPIC MATERIALS AFTER IMPACT
In this paper, the elastic-plastic dynamic response at the tip of semi-infinitecrack in the interface between two dissimilar orthotropic materials subjected to impact isinvestigated. By means of the integral transform, Wiener-Hopf technique and Cagniard-deHoop's inverting path,the analytic solution of the question is acquired,and then the dynamicintensity factor of the crack is also obtained. By using Dugdale mode,tWo relations areobtained.One is the extending velocity of its plastic domain with the propaga...
1994, 26(5): 551-558. doi: 10.6052/0459-1879-1994-5-1995-581
STATISTICAL ENERGY ANALYSIS FOR NON-CONSERVATIVELY COUPLED SYSTEMS UNDER HIGH- FREQUENCY WIDE-BAND CORRELATED EXCITATIONS
In this paper,based on the theory of power flow and energy distribution be-tween non-conservat ively co upled os cillators under correlated excit at ions, the equations ofenergy balance for the oscillators are derived and statistical energy analysis theory for non-conservatively coupled systems under correlated excitations is developed. The results showthat the input power vector is substited by the equivalent one, the symmetrical statisticalenergy parameter matrix is substited by the non-symmetical statis...
1994, 26(5): 559-569. doi: 10.6052/0459-1879-1994-5-1995-582
THEORY OF NONLOCAL ASYMMETRIC PLASTICITY
By the nonlocal continuum theory,with small strain and small local rotationassumption,we consider the effect of body couple for asymmetric stress field by assumingthat the energy functions of symmetric and the asymmetric part of stress can be formulatedindep endent ly By means of t he principle of thermo dynamics and the concept of yieldsurface,a new t heory for nonfo cal asymmet ric elasto- plasticity is est ablished
1994, 26(5): 570-582. doi: 10.6052/0459-1879-1994-5-1995-583
EVALUATION OF GREEN'S FUNCTION FOR A POINT DYNAMIC LOAD IN THE INTERIOR OF AN ELASTIC HALF-SPACE
A solution of Green’s function is presented for a point dynamic load in theinterior of an elastic half-space which fully satisfies the boundary conditions on the freesurface. By means of the modified Hankel functions,the infinite integral is transformed intofinite ones in the complex domain, which makes the evaluation of Green’s function easierand more conveniently This solution serves the theorectical basis for the application ofboundary element method in the analysis of dynamic soil-structure interaction ...
1994, 26(5): 583-592. doi: 10.6052/0459-1879-1994-5-1995-584
A NEW METHOD OF MODELING MULTIBODY SYSTEM
A new met hod of modeling multibody system is presented based on the prok-erty of constrains.The method have more strong computational stability and more highercomputational efficiency.
1994, 26(5): 593-598. doi: 10.6052/0459-1879-1994-5-1995-585
A NEW DIGITAL SPECKLE CORRELATION METHOD AND ITS APPLICATION
A new improved digital speckle correlation method一cross search method wasdescribed in this paper.The method will greatly reduce the computing time, and thus theapplications of digital correlation method using personal computer can be realized.Anewformula for calculating correlation coefficient wais presented based on the probability theoryBy this formula,the measuring accuracy of digital correlation method can be greatly im-proved.Some technique problems for obtaining high precision were discussed. The prim...
1994, 26(5): 599-607. doi: 10.6052/0459-1879-1994-5-1995-586
AN EXPERIMENTAL STUDY ON THREE-DIMENTIONAL TEMPERAIURE STRUCTURES OF BAROCLINIC WAVES IN A ROTATING FLUID SUBJECT TO A NEGATIVE RADIAL TEMPERATURE GRADIENT
In this paper, the covective motion of baroclinic fluidis studied experimentally inarotating annulus subject to a negative radialtem perature gradient. General characteristicsof baroclinic wave in this svstem have been obtained.Through measuring temperature fieldof baroclinic waves at many levers and fine grids,we have obtained the three-dimentionaltemperature structures of baroclinic wave and temperature distributions of quasi-surfacewave-state jetstream. The unstability of wave-wave transformation has als...
1994, 26(5): 608-615. doi: 10.6052/0459-1879-1994-5-1995-587
CONCENTRATION MEASUREMENT AND ITS TWO-DIMENSIONAL DIGITAL CALIBRATION BY A PLIF TECHNIQUE
The fluorescence intensity distributions in water tank are obtained for con-centration measurement by a PLIF technique, and a two-dimensional digital calibrationequation and method are then proposed in order to account for the nonuniform distributionand attenuation of intensity of a laser thin. Based on the above,the concentration field ofround turbulent jet is measured and calibrated. Finally, the results of jet are analyzed andcompared with those of the semi-empirical theory.
1994, 26(5): 616-624. doi: 10.6052/0459-1879-1994-5-1995-588
EFFECT OF LONGITUDINAL VORIICES ON THE TURBULENT STRUCTURE IN NEAR-WALL REGION
The effect of longitudinal vortices on the turbulent structure of near-wall regionWas investigated with hydrogen bubble technique in a rectangular duct A wider high-speedstreak appears in the downwash region of vortex(where secondary flow is directed towardsthe wall),the flow is stable and the streamwise velocity is higher inside the streak)a regionincluding low-speed streaks is shown in the upwash part of vortex (where the secondaryflow is directed away from the wall),the flow structure is complicated and ...
1994, 26(5): 625-630. doi: 10.6052/0459-1879-1994-5-1995-589
ROLE OF SUCTION AND PRESSUREGRADIENTIN THE TRANSITION PROCCES OF BOUNDARY LAYER
In the paper secondary instability theory is used to analyse the effect of suctionsand pressure gradients on the charact eristics of spatially growing 3-D subharmonic distur-baces in b oundary layer flow. The end res ults indicate that suctions shows an apparentlaminar flow control on the boundary layer flows,and unfavorable pressure gradients haveastrong destability effects.
1994, 26(5): 631-635. doi: 10.6052/0459-1879-1994-5-1995-590
ON A THEORY FOR ELASTOPLASTICITY OF COMPOSITES
A simple theory for describing elastoplastic behavior(nonlinear stress-strainrelations) of composites has been developed in terms of Green’s function theory and per-turbation method. For the metal-matrix composites reinforced with ceramic particles, twodifferent solutions,namely average t- matrix approximation(ATA) and coherent-potential ap-proximation(CPA), have been given. A calculation exainple of SiCp /Al composites indicatesthat the theoretical predictions are consistent with experimental results。
1994, 26(5): 636-640. doi: 10.6052/0459-1879-1994-5-1995-591