The relationship between plastic flow macrolocalization and a dislocation structure

We have established a quantitative relationship between the spatial period of localization of plastic straining and the parameters of the dislocation structure of a zirconium alloy. It is found that the wavelength of localized straining is proportional to the average size of elements of a dislocation substructure formed in the material in various stages of plastic flow. A quantitative interpretation of this relationship is proposed.     

The structure of laminar flow of gas from a porous mesh insert

The results are given of an experimental investigation of nonuniformities of velocity in the vicinity of an envelope of porous mesh materials under conditions of laminar flow of air from that envelope. The obtained data are generalized along with the available literature data. Techniques are planned and recommendations given for ensuring a local continuous outflow of gas coolant to a porous surface under conditions of transpiration cooling of the wall.     

The structure of gasdynamic flow in a supersonic separator of natural gas

Results are given of calculations of flow within the two-dimensional Euler model of supersonic swirling flow of gas in a supersonic separator of natural gas. The formulation of the problem is given, numerical experiment is performed, and the basic parameters of gas flow (velocity components, pressure, and so on) are obtained as functions of radius. The process of relaxation of flow to steady state with the formation of shock wave is considered, and the shock wave structure is determined. The behavior of gasdynamic parameters is analyzed under conditions of separation in the region of shock wave and behind it.     

Wave structure of turbulent flow in a tube

The wave theory of turbulence is applied to determine the fluctuation field u of shear flow in a tube.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 48, No. 5, pp. 738–746, May, 1985.     

Visualization of flow structure in a vortex furnace

The spatial structure of a swirling flow in a model vortex furnace with distributed input of fuel-air-mixture jets has been studied. The results of experimental and numerical investigations of a three-dimensional (3D) field of time-averaged velocities in an isothermal laboratory model of a vortex furnace have been used to image the structure of flow. Vortex structures have been identified using λ₂ and Q criteria, as well as the concept of “minimum total pressure.” The vortex core of the flow has a V-shaped 3D structure.     

Experimental study of flow structure and heat transfer under a jet flow past a spherical-cavity obstacle

The results of an experimental study of the aerodynamic characteristics and heat transfer under a jet flow past a spherical-cavity obstacle are presented. It has been revealed that in a spherical cavity the flow becomes nonstationary and is characterized by low-frequency oscillations of local values of the heat flow density. The heat transfer intensity in a hollow is lower than on a flat obstacle, and in the region of depression this decrease is practically completely compensated by an increase in the heat-transfer surface area. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 4, pp. 29–37, July–August, 2006.     

Formation of structure in a flow of a suspension of neutrally floating particles

It is shown that in a flow with a nonuniform vorticity, the concentration field of the suspension is also nonuniform. Stationary Couette and Poiseuille flows in a flat gap and in a capillary are examined in detail.     

Effect of thermal nonstationarity on the structure of a turbulent flow

Results of an experimental study on the effect of thermal stationarity on the flow structure are given.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 41, No. 4, pp. 621–624, October, 1981.     

Effect of surfactants on the flow friction and flow structure of a gas-liquid dispersion in a vertical annular channel

The authors report on the effect of adding a surfactant on two-phase flow structure, flow friction, and true gas content in an annular channel.     

Generation of intensive narrow-band disturbances in a flow with a large-scale hydrodynamic structure

This paper analyzes the reasons for the appearance of intensive narrow-band disturbances and self-sustained oscillations in a flow with an inhomogeneity on its boundary. It has been shown that self-sustained oscillations are due to the formation of large-scale cocurrent hydrodynamic systems with vortex structures and acoustic feedback. It is supposed that the vortex formed in the zone near the edge of the surface generates noise as a result of the involvement in the rotary motion of the azimuth-inhomogeneous structure. It is noted that self-sustained oscillations can be avoided or suppressed by disorganizing the elements of the large-scale hydrodynamic structure. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 4, pp. 682–689, July–August, 2008.     

Hydraulic parameters and structure for a gas-liquid flow in a spiral channel

Measurements have been made on the true volume gas content, pressure difference, and structural features of an air-water mixture moving in a spiral. The characteristics are similar to those of a two-phase medium flowing in a straight tube.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 2, pp. 199–203, August, 1987.     

The effect of bubbles on the structure of flow and the friction in downward turbulent gas-liquid flow

Results are given of a numerical study of local structure of downward gas-liquid flow in a vertical pipe. The numerical model is based on the use of two-liquid Eulerian approach. Investigation is performed of the impact made by the variation of the degree of dispersion of the gas phase, volumetric flow ratio of gas, channel diameter, and velocity of the liquid phase on the local structure and skin friction in two-phase flow.     

The flow of a fluid film entrained by a supersonic flow of gas

We have conducted an experimental study into the flow of a high-viscosity fluid directed through an orifice of small diameter onto the surface of a body contained within a supersonic flow of air.Notation M Mach number for the outlet cross section of the nozzle - Re_D Reynolds number calculated from the parameters of the unperturbed flow at the outlet section of the nozzle and from the diameter of model rounding - P₀ total pressure in the pressure chamber of the wind tunnel, Pa - T₀ deceleration temperature - sweepback angle of leading edge of plate (between the normal to the direction of the unperturbed flow and the generatrix of the leading edge), deg - d orifice diameter, mm - angle between direction of unperturbed flow and radius vector of orifice, deg - frictional stress at boundary separating fluid and gas, Pa - Q volumetric fluid flow rate, cm³/sec - kinematic viscosity of fluid, cSt - q /q_g ratio of the velocity head of the fluid at the outlet from the orifice to the local velocity head of the gas - thickness of fluid film, mm - b width of fluid film, mm - angle between tangents to the side boundaries of the fluid film, deg - s coordinate calculated from the center of the orifice along the midline of the film or along the axis of wedge symmetry, mm - z coordinate calculated along the normal to the axis, mm Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 59, No. 2, pp. 181–186, August, 1990.     

Response probability structure of a structurally nonlinear fluttering airfoil in turbulent flow

The stationary probability structure for the aeroelastic response of a structurally nonlinear fluttering airfoil subject to random turbulent flow is examined numerically. The airfoil is modelled as a two-dimensional flat plate with degrees of freedom in torsion and heave (vertical displacement). The nonlinearity is a hardening cubic stiffness force in the torsional direction. The aerodynamic force and moment are assumed to be linear, thus limiting the analysis to small oscillations; unsteady effects are retained. Furthermore, both parametric and external random coloured excitations are considered. It is found that depending on the value of turbulence variance and nonlinear cubic stiffness coefficient, the pitch marginal probability density functions (PDF) exhibits uni-, bi- or double bi-modality; the nature of the bi-modality is not unique. An explanation of the behaviour is provided via an analysis of the joint PDF in pitch and pitch rate for which both the deterministic and random responses are examined. More generally, it is found that the random excitation effectively ‘decouples’ the nonlinear responses such that the pitch, pitch rate, heave and heave rate marginal PDFs transition from uni- to bi-modality at different airspeeds. It is argued that a fundamental cause of the observed behaviour is the synergy between the nonlinearity and the random external excitation.     

Flow structure and heat transfer during the separation of a pulsating flow

The results of experimental studies of heat transfer in the separation region and the kinematic structure of the air flow in a channel behind a rib under superimposed discharge pulsations are presented. The effect of heat transfer enhancement of up to1.5 times in comparison with the stationary regime has been established. In the near wake behind the obstacle, it was up to five times. An observable decrease in the reat-tachment length (of up to two times) has been revealed under the pulsating flow regimes. The mechanism of these phenomena has been established, and typical features of the structure of pulsating separated flows have been described on the basis of the results of visualization experiments. The classification of these flows is proposed, and a regime map has been drawn up.     

Laser tomography for flow structure analysis

A laser tomography system is described that is intended for three-dimensional visualization and analysis of the processes occurring in hydromechanical and gasdynamic flows. Optical schemes are given of three-dimensional illumination of the region being investigated, based on the sweeping light sheet technique. The developed system of optical tomography is used to scan the flow structure being investigated by means of successive optical planes, and the resultant digital images are processed and reconstructed using computer techniques which make it possible to display three-dimensional images of the “frozen” surface structure of flow in different directions. Commercially available standard software packages are used for image and data processing. Results are given of the experimental investigation of a free jet flow by means of optical tomography     

Influence of polymer admixtures on the turbulence structure of flow behind a grating

Experimental investigations of the action of small (20–80 ppm) polymer admixtures on the turbulence structure in the wake behind a grating are performed in a water channel of closed type. The velocity fluctuations are measured by using a single-component Doppler laser velocimeter (DLV). A signal from the DLV was recorded on magnetic disc from three channel sections and the onedimensional energy and dissipation spectra were computed therefrom. It is shown that polymer insertion resulted in reduction of the turbulence level at short ranges from the grating and its increase far from the grating. Influence of the polymer in the spectral distribution appeared in an energy increase in the low-frequency domain and its fast degeneration in the high-frequency band, accompanied by contraction of the spectrum width.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 58, No. 4, pp. 550–556, April, 1990.     

The flow of a second grade fluid

A method for studying plane steady flows of a second grade fluid is discussed. Basic equations are recast in a new curvilinear coordinate system, by employing some results from differential geometry, and the partial differential equations are derived for the coefficients E, F and G of the first fundamental form of the metric, which are taken as unknown functions. By placing certain conditions on these coefficients, a priori, flows are determined which have such a property. Some illustrations in detail are given which reflect the use of this method.     

Flexibly driving micro flow in a Lab-on-Chip system via dry porous structure

This paper is dedicated to present a low cost way for flexibly driving micro flow in a Lab-on-Chip system through utilizing the wetting mechanism. The unique merit of the method lies in its intentional employment of the wettability between liquid and the dry porous structure. The device thus fabricated only constitutes with a piece of dry porous material and a micro tube filled with liquid. When starting driving, connecting the objective liquid to the micro tube with pre-filled liquid at the entrance; then attaching the dry material to the exit end of the micro tube. Due to wettability between the pre-filled liquid and the dry material, the volume of the pre-filled liquid would decrease which subsequently induce a pressure reduction in the micro tube. As a result, the objective liquid will be jammed into the micro tube by the atmospheric pressure. With this working principle, the driving device is provided with several advantages such as being simple, cheap, safe, and clean; it also owns a wide range of applications in micro fluidics analysis. Theoretical interpretation and demonstration experiments were performed to evaluate the working performances of the driving device. Several factors liable to affect the running state of the driving device have been proposed and evaluated. It has been proved that this driving device is highly feasible and can be adopted as a micro pump for disposable Lab-on-Chip.