力学学报

STUDY ON NEAR WAKE FLOWS OF A FLAT PLATE IN STEADY, OSCILLATORY AND COMBINED FLOWS

Numerical simulation of near wake flows of a flat plate in three kindsof oncoming flow is made using discrete vortex model and an improved vorticity creation technique. The gross features and detailed structure, such as velocity profile, turbulent intensities etc., of near wake of the flat plate in uniform oncoming flow are calculated and compared with available previous results. A new vortex mode, describing vortex shedding, pairing and moving in near wake of the plate for harmonic oscillatory oncoming flo...

1991, 23(5): 513-524. doi: 10.6052/0459-1879-1991-5-1995-871

PDF

AN EXPERIMENTAL STUDY OF FLUCTUATING LIFT ON A SQUARE-SECTION CYLINDER OSCILLATING TRANS-VERSELY IN A UNIFORM STREAM

Experiments on a square-sertion cylinder fixed and forced to oscillate transversely in uniform stream were conducted in a water tank. The Reynolds number of the experiments is in the range 3·103 to 104, the amplitude to side length ratio A/D is up to 0.7 and the range of reduced velocity 4.5≤Vt≤12.This study aims at investigating the lock-in phenomenon, fluctuating lift and the phase shift between fluctuating lift and displacement of the oscillating cylinder. The problems on the aeroelastic instability rela...

1991, 23(5): 525-532. doi: 10.6052/0459-1879-1991-5-1995-872

PDF

NUMERICAL SOLUTION OF SUPG FINITE ELEMENT METHOD FOR SUPERSONIC VISCOUS FLOW

A streamline upwind/Petrov-Galerkin (SUPG) weighted residual formulation has been developed in the present paper for the quasi-simplified N-S equations. Numerical calculations have been made for the Burgers' equation, the shock reflection on a solid wall, and the supersonic laminar flow over a flat plate and two-dimensional compression corner flow by using the present method. The numerical results show that the present method has good accuracy, convergence, and stability properties.

1991, 23(5): 533-541. doi: 10.6052/0459-1879-1991-5-1995-873

PDF

STEADY-SHEAR VISCOSITY AND TRANSIENT STRESS RESPONSE FOR ELASTO-THIXOTROPIC FLUIDS

A phenomenological mode! for dispersed systems which exhibit complex theological behaviour such as shear and time-dependent viscosity, yield stress, and elastici'y is proposed. The model extends the Quemeda model to describe the viscosity function with a structural parameter A which varies according t'o different kinetic orders of particle aggregation and segregation. The transient stress response is obtained by solving on instantaneous Maxwell model with an assumed shear modulus function G of the same form...

1991, 23(5): 542-548. doi: 10.6052/0459-1879-1991-5-1995-874

PDF

THREE EXACT SOLUTIONS OF INCOMPRESSIBLE POTENTIAL FLOW INDUCED BY TWO CIRCLES

Lagally (1929) has given the exact solution for the two dimensional incompressible potential flow indued by two fixed circles in a uniform stream. In this paper, three exact solutions are obtained for two dimensional incompressible potential flow induced by two circles moving or expanding in a still fluid in three cases: (i) expansion (or contraction) of themselves, (ii) approach to (or departure from) each other, (iii) their movements perpendicular to the connected-centre-line in opposite directions.

1991, 23(5): 549-555. doi: 10.6052/0459-1879-1991-5-1995-875

PDF

INVERSE MODE OF CALCULATION OF THREE-DIMENSIONAL INCOMPRESSIBLE SEPARATED FLOWS IN BOUNDARY LAYER

In this paper an inverse mode of calculation of separated flows in the three-dimensional incompressible boundary layer is presented. The curvilinear semiorthogonal coordinate system and a turbulence model considering the anisotropy of eddy-viscosity are used. And the transformed coordinates and the Keller's box method are applied in the numerical analysis. The calculated results are found in good agreement with experimental data.

1991, 23(5): 556-563. doi: 10.6052/0459-1879-1991-5-1995-876

PDF

FURTHER STUDY OF THE IDENTITY OF INCOMPATIBLE DISPLACEMENT ELEMENT AND GENERALIZED HYBRID ELEMENT

本文通过定义非协调位移元的单元特性函数,提出了一种建立非协调元与广义杂交元之间的等价关系的一般方法,进一步证明了两种有限元模型之间存在强等价性,为两种单元模型的构造提供了相互借鉴的理论依据和有效的准则。

1991, 23(5): 564-570. doi: 10.6052/0459-1879-1991-5-1995-877

PDF

THE ANTI-PLANE SHEAR FIELD FOR CRACK IN INFINITE SLAB OF AN ELASTO-DAMAGED MATERIAL

This paper is concerned with an infinite slab containing a semi-infinite crack, which is subjected to the anti-plane shear km field at infinity. The slab is made of elasto-damaged material. The analytical solution is obtained by use of conformal mapping. The shape of damage zone, damage dissipative enetgy, shear opening displacements on crack surface and some stress distribution curves are shown. The far field condition is checked. The asymptotic behavior near the tip of the crack is given.

1991, 23(5): 571-580. doi: 10.6052/0459-1879-1991-5-1995-878

PDF

DISPLACEMENT WAVE OF THE BLOOD VESSEL-A MECHANICAL MODEL

According to the clinical observations and model experiment, we have de-veloped a theoretical model and its mathemational equations to investigate the displacement wave of the blood vessel. The wave performance and its criterion of occurrence have been obtained by using perturbation theory and numerical method. The present study suggests that the displacement wave is governed by the blood velocity wave performance and the machanical behavior of the blood vessel, not the pressure performance. A clinical crit...

1991, 23(5): 581-588. doi: 10.6052/0459-1879-1991-5-1995-879

PDF

MOIRE INTERFEROMETRY FOR MEASURING 3-D DISPLACEMENT FIELDS IN REAL TIME SIMUTANEOUSLY

A specially arranged moire interferometry is proposed for measuring 3-D displacement fields in real time simuraneously. An optical arrangement is developed, which consists of three interferometry systerms: one normal incidence holographic interferometry and two Moire interferometry arrangements. An experimental demonsf-ation is conducted using a disc specimen with a high frequency cross line grating on its surface. The normal-mcidence holographic interferometry is used for obtaining the out of plane displac...

1991, 23(5): 589-594. doi: 10.6052/0459-1879-1991-5-1995-880

PDF

PULSED HOLOGRAPHIC AND SPECKLE INTERFEROMETRY TO INVESTIGATE THE DEFORMATION ON PLATES

The major objective of this study is to investigate the dynamic experimental technique about the deformation, of the finite-circular metal plates after normal impact. Holographic interferometry and defoeus speckle photography are utilized to record "he transient response of plates. Synchronization of the event with the pulses from the new type DJ-1 ruby laser is accomplished with the electronical equipment designed by the authors. Hot.kmson type instrumented bar loading apparatus is used to determine the lo...

1991, 23(5): 595-600. doi: 10.6052/0459-1879-1991-5-1995-881

PDF

EXPERIMENTAL STUDY ON TURBULENT CHARACTERISTICS UNDER BUCKET ENERGY DISSIPATORS BY USING A 2-D LDA SYSTEM

Turbulence measurements downstream of an energy dissipators, including the rever.se flow region were performed using a two-dimensional Laser Doppler Anemometer (2-D LDA). The mean velocity distributions, turbulence intensities and Reynolds shear stresses were revealed in and around the separated shear layer and recirculation region. The patterns of the streamlines were calculated and drawn, and then, the reattachtnent properties were stu-died varying with Froude numbers. Finally, the transition process of t...

1991, 23(5): 601-608. doi: 10.6052/0459-1879-1991-5-1995-882

PDF

EXPERIMENTAL GH SINGULARITY FIELD AROUND GROWING CRACK TIP

The displacement fields ux,uy of growing crack tip for LY12-M material specimens with double edge cracks are measured using Moire method. The experimental singularity fields are compared with GH theoretical field. The size and shape of the experimental GH singularity fields are obtained. The di screpancy of experiment and theory is within ±10%. The experiments show thatthere is (InA/r)α+1 singularity dominant around growing crack tip. The shape of thisregion of dominant singularity are batterfly wing, then ...

1991, 23(5): 606-616. doi: 10.6052/0459-1879-1991-5-1995-883

PDF

ABOUT THE BASIC INTEGRAL VARIANTS OF HQLONOMIC NONCONSERVATIVE DYNAMICAL SYSTEMS

In this paper, we prove that for holonomic nonconservative dynamical systems the integral invariant of Poincare and Cartan and the universal integral invariant of Poincare do not exist. Instead of that, we introduce the integral variants of Poincare and Car-tan's type and of Poincare type for holonomic nonconservative dynamical systems, and use those variants to solve the problem of nonlinear vibration. We also prove that the integral invariants introduced in references [1] and [2] are merely the basic inte...

1991, 23(5): 617-625. doi: 10.6052/0459-1879-1991-5-1995-884

PDF

MECHANISM ANALYSIS ON ATOMIZATION OF A NON-NEWTONIAN FLUID JET

A linearized stability analysis and a numerical calculation are carried out for the mechanism of atomization of a second-order fluid jet. In spite of the importance of atomization in applications, the mechanism that controls atomization processes has not yet been made clear even though several theorys have been proposed. In this paper the viscosity effects and elasticity effects of a second-order fluid for the atomization process are determined qualitatively and compared with Rei'z and Bracco's experimental...

1991, 23(5): 626-633. doi: 10.6052/0459-1879-1991-5-1995-885

PDF

AN INVESTIGATION INTO THE FIELD IDENTIFICATION TECHNIQUE OF MODAL PARAMETERS OF ROTATING SYSTEM

Based on the time-domain vibrating parameter identification theory, the field identification technique of modal parameters or rotating system composed of oil-film bearings and rotor is investigated in the present paper. The method proposed by this paper does not need artifical excitation force and oniy needs the vibration signal of bearings and neck journals. This method can be applied on-line.

1991, 23(5): 634-640. doi: 10.6052/0459-1879-1991-5-1995-886

PDF

1991 Vol. 23, No. 5

NoticeMORE+

Exquisite ArticlesMORE+

Download Center

Author Center