Electrogas- and electrohydrodynamic control of gas and liquid jets and flows. 2. Physical principles

The paper deals with the electrophysical principles of the method of electrogas- and electrohydrodynamic conversion of electric signals to pneumatic (hydraulic) signals and vice versa for the control of gas and liquid jets and flows in electropneumohydraulic systems, including problems of formulating requirements for the working media and electric circuits of converters, estimating the limiting ranges of pressure, velocity, and temperatures of the working media and limiting dynamic possibilities, and determining conditions for production of potential signals, stable control, and extension of the control ranges. St. Petersburg State Technical University, St. Petersburg 195251. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 3, pp. 34–42, May–June, 2000.     

Gas-dynamic shock waves in a relaxing gas

St. Petersburg State University, St. Petersburg 199004. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 36, No. 3, pp. 92–97, May–June, 1995.     

Effect of viscosity of the wave process in a nonuniform flow with a critical level

A continuous analytical representation of an acoustic-gravitational field in a medium with a nonuniform flow in the presence of a critical layer is constructed. It is shown that taking into account the effect of viscosity eliminates singular values of the field. St. Petersburg State University, St. Petersburg 198904. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 2, pp. 97–101, March–April, 2000.     

Structure of the plasma jet of a pulsed erosional electric-discharge source

St. Petersburg. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, No. 5, pp. 13–18, September–October, 1994.     

Special features of self-sustained oscillations in a supersonic underexpanded jet impinging on an obstacle with a restricted cross-section

Effect of the obstacle size on the flow structure and the transient conditions arising in a supersonic underexpanded jet normally impinging on a flat restricted obstacle is studied. Baltic State Technical University, St. Petersburg 198005. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 4, pp. 143–149, July–August, 1999.     

Properties of pulsating blood flow through resistive blood vessels

The results of measuring the resistance when the flow changes from steady to pulsating are discussed on the basis of simple mathematical models of the individual vessel and the microvascular module. Moscow, St Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.2, pp. 83–89, March–April, 1994.     

Maximum turning angles of a supersonic flow in shock-wave systems

The possibility of creating shock-wave systems to achieve maximum supersonic flow turning angles is considered. The relation between these systems and both geometrically conditioned optimal systems and the shock-wave structures formed as a result of interaction between gasdynamic discontinuties is investigated. St. Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 3, pp. 148–156, May–June, 1998.     

Shock-wave structure in a dispersing plasma

The shock-wave structure in an isotropic plasma is studied in the scale of the Debye shielding radius. The boundary condition at “infinity” is due to the dissipation mechanism of ions reflected from the ion wavefront. The case of the absence of dissipation corresponds to a collisionless shock wave. It is known that there is a critical Mach number above which the laminar shock wave is impossible. In addition, two types of boundary conditions which occur if collisions in an equilibrium high- and low-ionized plasma are taken into account are considered. The reflected ions are assumed to be scattered by electrons in the first case, and the momentum of the reflected ions is assumed to be transferred to uncharged particles in the second case. The critical Mach number of a shock wave does not exist under the conditions of collision dissipation of a flux of reflected ions. St. Petersburg State University, St. Petersburg 198904. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 14–21, May–June, 1998.     

Scale-up criterion of turbulent flows of dilute polymer solutions and a generalized dependence of the friction coefficient

Dilute polymer solutions that reduce turbulent friction are treated as viscoelastic liquids for which, in addition to the Reynolds number, the scale-up criteria include the Deborah or elasticity number. Introduction of a generalized (viscoelastic) Reynolds number makes it possible to reduce the experimental curves for the drag coefficients obtained in pipes of various diameters at different and concentrations to a unified dependence. St. Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 191–196, July–August, 1998.     

On the transient regime in nonstationary supersonic flow past a body

The transient regime in gas flow past a stepwise accelerated body is analyzed by the method of singular perturbations at small Froude numbers. A marked effect of the initial conditions on the shock layer gas flow is demonstrated. The problem of flow past a wedge is solved in quadratures. St.Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 111–121, January–February, 1997.     

Bottom effect on limiting Stokes waves

The problem of limiting progressive Stokes waves characterized by a crest angle of 120° propagating in an inviscid incompressible fluid of finite depth is solved numerically. The wave forms are obtained and the range of Froude numbers, calculated from the fluid depth and the phase velocity, on which solutions exist is determined. St. Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 125–129, July–August, 1994.     

Gas-dynamic method of decreasing the force of penetration of a solid into ground

A new gas-dynamic method for decreasing the resistance of ground to the penetration of a solid body is developed. The physical essence of the process is considered. Theoretical fundamentals of scaled modeling are given. Results of experimental studies are presented, and the range of parameter for which the method is effective is determined. Mozhaiskii Military Space-Engineering Academy, St. Petersburg 197082. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 3, pp. 196–199, May–June, 1999.     

Decay of a centered prandtl-mayer compression wave in a steady gas flow

Discontinuity decay at a singular point of a centered compression wave is considered. Analytical solutions are given that allow one to determine the type of reflected discontinuity that issues from the point of decay and the boundaries of ranges of parameters within which a solution of the problem exists. Baltiisk State Technical University, St. Petersburg 198005. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 3, pp. 59–68, May–June, 1998.     

Ablation of a hydrogen pellet in a light-gas gun bore

An ablation model for a hydrogen pellet accelerating in a thermonuclear facility fuel-injector bore is developed. The model is based on the Lagrange internal-ballistic problem complemented by the Stefan conditions on the ablating surface of the pellet Calculations demonstrate that, during pellet motion in the bore under the action of the gas, the pellet length remains almost unchanged, while due to the heat exchange with the bore walls the pellet diameter decreases by 4–10% St. Petersburg. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 1, pp. 3–11, January–February, 1999.     

Numerical studies of transportation of granular material by a pin-point blast using models of the mechanics of continuous and granular media

Mathematical models for numerical studies of transportation of a mass of loose granular material during occurrence of a series of deep gas-dynamic ejections are developed using methods of the mechanics of continuous and granular media. Features of the kinematics and dynamics of development of this phenomenon are analyzed. Results of a numerical experiment and recommendations on use of the models in studies of specific transportation regimes are given. Mozhaisk Military Space-Engineering Academy, St. Petersburg 197082. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 1, pp. 3–14, January–February, 1998.     

Description of mass growth of crystals from solutions with allowance for the disappearance of crystal faces during crystal growth

Mass crystallization was studied on the basis of a crystal-size distribution function for a kinetic law of growth of faces (when the growth rate of a crystal face does not depend on the size and shape of the face) and with allowance for vanishing of individual faces during crystal growth. It is proposed that the crystallization problem should be reduced to a system of equations that admit analytical solutions in some cases of practical interest. Russian Research Center “Applied Chemistry,” St. Petersburg 197198. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 39, No. 2, pp. 121–134, March–April, 1998.     

Behavior of the unsteady jet of a mixture of a pressurized gas and dispersed particles discharged from a circular duct into the atmosphere

The unsteady axisymmetric jet produced by discharge of a mixture of a pressurized gas and dispersed particles from a circular duct into the atmosphere is studied within the framework of two-velocity, two-temperature gas dynamics. An attempt is undertaken to allow for the effective pressure due to random particle motion. The collision mechanism is found to be essential to radial expansion of the flow. Experimental data that support the results obtained are reported. Mozhaiskii Military Spacecraft Engineering Academy, St. Petersburg 197082. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 1, pp. 151–157, January–February, 1999.     

Numerical analysis of vortex cell efficiency in laminar and turbulent flows past a circular cylinder with embedded rotating bodies

The effect of flow intensification in small-sized vortex cells on the flow pattern in the near wake downstream of a cylinder and the cylinder drag in laminar and turbulent flows is analyzed on the basis of a numerical simulation of the two-dimensional steady-state flow past a circular cylinder with rotating cylindrical bodies built into the cylinder contour. St. Petersburg, Saratov. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No. 4, pp. 88–96, July–August, 2000. The study was carried out with the support of the Russian Foundation for Basic Research (projects Nos. 99-01-01115 and 99-01-00772).     

Numerical study of initial pulsed motion of a powder layer in a duct under the action of a compressed gas

One-dimensional plane pulsed joint motion of a gas phase and a disperse phase in the presence of friction of the latter against the duct walls are studied numerically using the model of a heterogeneous medium. It is established that two qualitatively different regimes of motion are possible, depending on the initial conditions in a high-pressure chamber and the value of the friction factor. It is found that the powder exit velocity is self-similar with respect to friction. Mozhaiskii Military Space Engineering Academy, St. Petersburg 197082. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 40, No. 6, pp. 122–127, November–December, 1999.     

Pulsed discharge of a two-phase medium from a bounded duct capable of longitudinal motion

The regularities of the initial stage of discharge of a two-phase disperse medium from a bounded duct capable of longitudinal motion are established. Numerical results obtained within the framework of a medium with nonequilibrium for velocities and temperatures are compared with analytical solutions of the equilibrium mechanics of disperse systems for the case where the characteristic time of the process is of the order of the characteristic times of velocity and thermal relaxation or smaller. Mozhaiskii Military Space Engineering Academy, St. Petersburg 197082. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 41, No. 1, pp. 84–91, January–February, 2000.