Pressure Waves in a Gas–Liquid Medium with a Stratified Liquid–Bubbly Mixture Structure

Evolution and decay of pressure waves of moderate amplitude in a vertical shock tube filled by a gas–liquid medium with a nonuniform (stepwise) distribution of bubbles over the tube cross section are studied experimentally. The gas–liquid layer has the form of a ring located near the tube wall or the form of a gas–liquid column located in the center of the tube. It is shown that the nonuniformity of bubble distribution over the tube cross section increases the attenuation rate of pressure waves.     

Motion of a cylindrical cavity near a free boundary of a liquid

The dynamics of a cylindrical cavity in a liquid with no allowance for vertical displacement are considered in [1–3]. The present study investigates the pulsation motion of a cylindrical cavity near a free boundary of a liquid, allowing for displacement of the axis of the cavity in the vertical direction.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 173–176, November–December, 1988.     

Application of the Density-Functional Method for Numerical Simulation of Flows of Multispecies Multiphase Mixtures

Numerical examples of application of the density functional used to describe isothermal flows of two-phase two-species mixtures are given. The following flows are calculated in a two-dimensional formulation: impact of a drop on a liquid layer, breakdown of a drop in the velocity field of the Couette flow, formation of the wetting angle of a drop on a solid surface, and development of the Rayleigh–Taylor and Kelvin–Helmholtz instabilities at the gas–liquid interface.     

Electroconvective stability of a weakly conducting liquid

In inhomogeneous electric fields, at sufficiently high field strengths, a weakly conducting liquid becomes unstable and is set in motion [1–4]. The cause of the loss of stability and the motion is the Coulomb force acting on the space charge formed by virtue of the inhomogeneity of the electrical conductivity of the liquid [4–13]. This inhomogeneity may be due to external heating [4–6], a local raising of the temperature by Joule heating [2, 7, 8], and nonlinearity of Ohm's law [9–13]. In the present paper, in the absence of a temperature gradient produced by an external source, a condition is found whose fulfillment ensures that the influence of Joule heating on the stability can be ignored. Under the assumption that this condition is satisfied, a criterion for stability of a weakly conducting liquid between spherical electrodes is obtained.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 137–142, July–August, 1979.     

Development of ship waves in a nonhomogeneous liquid

The article discusses the three-dimensional problem of unsteady-state waves arising on a free surface and at the interface between two liquids of different densities, with motion of the source. Analogous problems for steady-state waves in a two-layer liquid have been investigated in [1–6], and for unsteady-state waves in a homogeneous liquid in [7, 8].Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 137–146, July–August, 1970.     

Surface waves and stability of free surface of a magnetizable liquid

Linear theory of surface waves in a magnetizable liquid is examined. A stability criterion for a plane-free surface of a magnetizable liquid is studied for an arbitrary magnetization law.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 4, pp. 35–40, July–August, 1974.     

Prediction of amount of entrained droplets in vertical annular two-phase flow

Prediction of amount of entrained droplets or entrainment fraction in annular two-phase flow is essential for the estimation of dryout condition and analysis of post dryout heat transfer in light water nuclear reactors and steam boilers. In this study, air–water and organic fluid (Freon-113) annular flow entrainment experiments have been carried out in 9.4 and 10.2 mm diameter test sections, respectively. Both the experiments covered three distinct pressure conditions and wide range of liquid and gas flow conditions. The organic fluid experiments simulated high pressure steam–water annular flow conditions. In each experiment, measurements of entrainment fraction, droplet entrainment rate and droplet deposition rate have been performed by using the liquid film extraction method. A simple, explicit and non-dimensional correlation developed by Sawant [Sawant, P.H., Ishii, M., Mori, M., 2008. Droplet entrainment correlation in vertical upward co-current annular two-phase flow. Nucl. Eng. Des. 238 (6), 1342–1352] for the prediction of entrainment fraction is further improved in this study in order to account for the existence of critical gas and liquid flow rates below which no entrainment is possible.Additionally, a new correlation is proposed for the estimation of minimum liquid film flow rate at the maximum entrainment fraction condition. The improved correlation successfully predicted the newly collected air–water and Freon-113 entrainment fraction data. Furthermore, the correlations satisfactorily compared with the air–water, helium–water and air–genklene experimental data measured by Willetts [Willetts, I.P., 1987. Non-aqueous annular two-phase flow. D.Phil. Thesis, University of Oxford]. However, comparison of the correlations with the steam–water data available in literature showed significant discrepancies. It is proposed that these discrepancies might have been caused due to the inadequacy of the liquid film extraction method used to measure the entrainment fraction or due to the change in mechanism of entrainment under high liquid flow conditions.     

On the use of salt tracers for measuring the dynamics of a liquid by optical methods

During the sedimentation of small salt crystals in a stationary liquid, long cylindrical salt tracers are formed; it is proposed to use these in studying free flows during the pulsed turbulization of the liquid.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 70–74, September–October, 1973.     

Numerical simulation of unsteady inviscid flows with free surfaces

The boundary element method is used to calculate numerically the unteady flow of a capillary liquid associated with the interaction of an expanding gas cavity and the free surface of the liquid.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 3–7, March–April, 1990.     

Problem of Increasing the Survivability of Two–Stage Ballistic Guns

The paper proposes methods for increasing the survivability of light–gas guns, including new designs and nonconventional modes of shot. It is established theoretically and experimentally that a decrease in the cone angle of the conical adapter to 2.5 — 3° leads to a severalfold increase in the survivability of the high–pressure chamber. A compound piston with a liquid or gel–like filler is designed. The mode of shot from a light–gas gun with superlight pistons and without a diaphragm is justified and tested experimentally. Conical and measuring adapters with liners made of thermally– and wear–resistant alloys are designed to prevent ablation of the light–gas gun barrel.     

Influence of the atmosphere on the magnitude of the hydrodynamic forces in the case of a disk in a flat encounter with the surface of a compressible liquid

If the velocities with which bodies enter liquids are small, and the bodies are not too blunt, the magnitudes of the hydrodynamic forces can be satisfactorily determined in the framework of the approximation of an incompressible liquid and depend on the density of the liquid, the velocity of entry, and the geometrical parameters (shape of the body, angles of entrance and attack). If the velocity is increased or the encounter with the surface becomes nearly flat, the compressibility of the liquid and the presence of an atmosphere begin to influence the hydrodynamic forces significantly. The influence of the compressibility on the magnitude of the impact loads has been investigated theoretically and experimentally [1–8]. The influence of the atmosphere in the case of an incompressible liquid has also been taken into account [9–11]. In the case of a flat encounter the two factors (compressibility of the liquid and presence of the atmosphere) simultaneously influence the development of the impact process. The present paper reports experimental results and computer calculations of the impact loads in the case of a flat encounter of a disk and the surface of a compressible liquid in atmospheres of helium, air, and freon.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 15–20, May–June, 1984.     

Determination of the frequencies of the oscillations of a low-viscosity liquid rotating in an axisymmetric vessel

The damping rate and frequencies of the normal modes of a low-viscosity liquid rotating in an axisymmetric vessel are found. The boundary-layer method enables one to express the result in terms of the solutions of the corresponding problem for an ideal liquid.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 128–133, March–April, 1980.     

Numerical simulation of the dynamics of a liquid in a moving axisymmetric cavity

The problem of the motion of an ideal liquid with a free surface in a cavity within a rigid body has been most fully studied in the linear formulation [1, 2]. In the nonlinear formulation, the problem has been solved by the small-parameter method [3] and numerically [4–7]. However, the limitations inherent in these methods make it impossible to take into account simultaneously the large magnitude and the threedimensional nature of the displacements of the liquid in the moving cavity. In the present paper, a numerical method is proposed for calculating such liquid motions. The results of numerical calculations for spherical and cylindrical cavities are given.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 174–177, March–April, 1984.     

On the determination of nonlinear oscillations of a liquid in a circular cylinder sector

The main hydrodynamic coefficients of equations, describing large oscillations of an ideal incompressible and homogeneous liquid in tanks having the form of a cylindrical sector are calculated. Nonlinear oscillations of a liquid in cylindrical containers have been investigated in [1–3]. Here we use the method of solving some nonlinear problems of the oscillations of an ideal liquid in arbitrary containers, proposed in [4]. The dependence of the calculated coefficients on the geometrical parameters of the tank, which is important in practical applications, is analyzed.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 124–131, September–October, 1970.The authors thank G. S. Narimanov for attention and advice.     

Dynamics of soluble gas bubbles

The problem of the mass, thermal and dynamic interaction between a bubble containing a soluble gas and a liquid is considered. It is shown that this problem can be reduced to the problem of the behavior of a vapor bubble with phase transitions investigated in detail in [1–3]. Expressions are obtained for the rate of decay of the radially symmetric oscillations of the bubbles due to the solubility of the gas in the liquid. The effective coefficients of mass transfer between the radially pulsating bubbles and the liquid are determined. A numerical solution is obtained for the problem of the radial motion of a bubble created by a sudden change of pressure in the liquid which, in particular, corresponds to the behavior of the bubbles behind the shock front when a shock wave enters a bubble screen.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 6, pp. 52–59, November–December, 1985.     

Theoretical and experimental investigation of funneling in liquids draining from axisymmetric vessels

The axisymmetric draining of a high-viscosity liquid from conical and cylindrical vessels is investigated with allowance for the change in the shape of the free surface.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 4, pp. 20–25, July–August, 1988.The authors are grateful to A. F. Olitskii for determining the viscosity characteristics of the experimental liquid.     

Experimental investigation of laminar flow of a liquid with a free surface in triangular-shaped channels

Results are given of an experimental study of laminar flow of a liquid in triangular-shaped open channels with tangential frictional stress at the free surface. Experiments were carried out when the liquid flow in inclined triangular-shaped channels had Reynolds numbers R < 10 and the working range of Reynolds numbers of the approach air stream was R = (1.6–3.6)·10⁴. The data are presented in relative coordinates as a dependence of the hydraulic resistance coefficient of the liquid on the tangential frictional stress at the free surface. It is shown that with an increase of the tangential frictional stress the hydraulic resistance coefficient considerably increases.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 1, pp. 168–170, January–February, 1977.     

Hydrodynamics of a liquid with deformable and interacting particles

Interest in the hydrodynamics of a liquid with particle rotations and microdeformations has recently intensified [1–9] in connection with the technical applications of different artificially synthesized structured media. A model of a liquid with deformable microstructure was first proposed in [4] and was thermodynamically analyzed in [6], in which a model of a liquid was constructed by means of methods from the thermodynamics of irreversible processes. A model of a macro- and microincompressible liquid with particle rotations and deformations has been proposed [7, 8] based on constitutive equations from [6]. Below we will solve the sphere rotation problem in an infinite liquid given different boundary conditions on the rates of particle rotation and microdeformation within the context of the system of equations presented in [7]. The solution of an analogous problem for a micropolar liquid simulating a suspension with solid particles has been obtained [9] and the solution for a viscous liquid was found by Stokes in [10].Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnieheskoi Fiziki, No. 1, pp. 79–87, January–February, 1976.     

Motion of a viscous liquid between two rotating spheres

An analysis is presented of the steady-state asymmetric motion of an incompressible viscous liquid between two concentric spheres rotating with constant angular velocities about various axes passing through their common center. The reaction force of the liquid on the inner sphere is determined; this force reduces to a resistive torque.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 179–180, May–June, 1974.     

Forces exerted by a liquid on a vapor bubble growing within IT

Using the basic equations of hydromechanics and also the Lagrange equations of the second kind, expressions are derived for the force acting between a liquid and a vapor bubble growing within it. Cases studied include those of the growth of a bubble on a thin filament or plane surface in an ideal liquid and a liquid of low viscosity. The sign of the hydrodynamic forces depends on the particular law of growth of the vapor bubble.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 3, pp. 165–170, May–June, 1973.