Separation curves of a flow classification apparatus of finite length

A simplified model of operation of a flow classification apparatus of finite length for the case of a low-concentrated suspension has been analyzed. An analytical and numerical analysis of the behavior of the separation function has been made. Particular emphasis has been placed on such characteristics of classification as the size and sharpness of separation. A self-similar solution for the concentration of particles in each phase has been obtained and compared to the numerical solution. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 171–178, May–June, 2006.     

Investigation of regimes of thermogravitational convection of a fluid between coaxial semicylinders with a heat-conducting shell in the presence of a local energy source

A numerical analysis has been made of the thermodynamic regimes of natural convection of a Newtonian fluid satisfying the Boussinesq approximation in the gap between coaxial semicylinders with finitely-thick walls in the presence of the heat-release source under the conditions of convective heat exchange with the environment. A mathematical model has been formulated in the dimensionless variables current function–velocity vorticity vector–temperature in polar coordinates. Streamlines and velocity and temperature fields reflecting the influence of the Prandtl number Pr = 0.7 and 7.0, the nonstationarity factor 0 < τ ≤ 300, the dimensions of the energy source, and of the relative thermal conductivity on the flow regimes and heat transfer have been obtained.     

Filtration of a gas-condensate mixture near the hydraulic fracture

The problem of filtration of a gas-condensate mixture near the operating well with a hydraulic fracture has been investigated. It was assumed that flow is three-dimensional in the matrix and two-dimensional on the fracture. It has been shown that for steady-state flow, the problem is split into a purely physicochemical problem on phase transitions and a nonlinear partial boundary-value problem for the pressure field. An example of numerical solution for the fracture with a prescribed conductivity field has been given. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 3, pp. 409–416, May–June, 2008.     

Simulation of the supersonic turbulent flow around a cylinder with coaxial disks

The turbulent axisymmetric flow around a stepped body — a cylinder with coaxial front and rear disks — has been calculated with the aid of a VP2/3 package based on multiblock computational technologies and the generalized procedure of pressure correction. The computational model has been tested with the example of a supersonic flow around a sphere. The numerical forecasts made with the use of Spalart–Allmares shear stress transfer and eddy viscosity transfer models have been compared with the data of the aeroballistic experiment, wind tunnel tests, and the results of the calculation of the flow around the disk–cylinder arrangement by a simplified zonal model in a wide range of variation of the incident flow Mach number (from 1.5 to 4). We have obtained a good agreement between the calculated transverse flow density distributions in the front stalling zone and those determined from the interferograms for the wave-drag-rational disk–cylinder arrangement. The influence of the rear disk on the drag of the disk–cylinder–disk arrangement has been estimated.     

Dynamics of the viscous interaction of a ring vortex with a flat screen

A separation turbulent flow has been mathematically simulated on the basis of numerical solution of nonstationary Navier-Stokes equations for determining the dynamics of viscous interaction of a ring vortex with a flat screen. The problem was solved for an axisymmetric turbulent flow at Reynolds numbers falling within the range 10⁵–10⁷. On the basis of the calculation data obtained, the interaction of a ring vortex with a turbulent flow induced on the screen and with the secondary ring vortices was investigated. The data obtained are in qualitative agreement with the analogous data obtained by other authors with the use of the discrete-vortex method and the boundary-layer theory as well as with the available experimental and calculation data obtained for a laminar flow. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 1, pp. 184–190, January–February, 2008.     

Numerical investigation of the laminar shock-wave gas flow excited by harmonic vibrations of the piston in a closed cylindrical tube

The shock-wave gas flow in a closed cylindrical tube caused by harmonic vibrations of a flat piston has been considered. The solution has been obtained by means of numerical integration of the system of nonstationary equations of a narrow channel written in divergent form. A scheme of the 1st order of time accuracy and a scheme of the 2nd order of space accuracy have been used. The regularities in the behavior of the dynamic and temperature boundary layers for the unstable regime of gas flow in the tube at various moments of the cycle have been analyzed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 2, pp. 139–144, March–April, 2006.     

Calculation of unsteady flow past a cube on the wall of a narrow channel using URANS and the Spalart–Allmaras turbulence model

The results of numerical simulation of fully developed turbulent flow in a channel with the cube on the lower wall (for the characteristic Reynolds number Re = 40,000) within the framework of the traditional approach to the solution of unsteady Reynolds-averaged Navier–Stokes equations (URANS) in combination with the semiempirical Spalart–Allmaras turbulence model (with a correction for rotation) have been presented. A detailed comparative analysis of the results of numerical simulation of local and integral flow characteristics and the Martinuzzi experimental data has shown that the self-oscillating regime of flow past the cube is a superposition of oscillations of the arms of a horseshoe vortex and the rear arched and detached vortex structures. Using fast Fourier transformation, it has been found that the oscillations are of a bimodal character in the longitudinal and vertical directions, whereas in the transverse direction, they are of a unimodal character.     

Simulation of the turbulent mixing of a passive impurity in a jet mixer

Results of numerical simulation of the mixing of a turbulent jet with a cocurrent incompressible-fluid flow (Schmidt number Sc ≈ 1000) in a cylindrical channel of circular cross section (axisymmetric mixer) with the use of the standard k-ε turbulence model and different models for the averaged value of the mixture fraction and its variance have been given. For the problem of mixing of an inert passive impurity, two regimes of flow — the regime with the formation of a recirculation zone and that without its formation — have been considered. The formulated statistical model has been verified with the use of experimental data and results of calculation by large-eddy simulation. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 4, pp. 666–681, July–August, 2008.     

Mathematical simulation of a supersonic flow around complex objects. Influence of the position of a wing on the gasdynamic characteristics of a complex object

Results of numerical simulation of a supersonic flow around spatial configurations of flying vehicles with the use of the Euler equations are presented. A model of a complex object was constructed on the basis of simpler base objects. Results of numerical solution of the problem on a three-dimensional flow around objects with an ogival-cylindrical airframe and a triangular wing with a diamond-shaped profile, arranged in different ways, at a Mach number M_∞ = 4.03 and an angle of attack α = 10.1^o have been analyzed. Calculation data were compared with the analogous data of a physical experiment. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 47–55, May–June, 2006.     

On the dynamic strength of a disk with a central cylinder-conic opening

The problem of nonstationary dynamic behavior of a disk weakened by a central cylinder-conic opening under the action of suddenly applied loading is considered. Determining relations are given in the form of a system of integral equations in an arbitrary oblique coordinate system. A numerical solution has been obtained by using a hybrid difference scheme constructed on the basis of the method of flow correction. Our generalized versions of the S.K. Godunov method for the case of a nonorthogonal system of coordinates were used as basic schemes. The locations of maximum stresses that precede the appearance of plasticity zones have been determined for a particular elastic body. Translated from Problemy Prochnosti, No. 2, pp. 79–87, March–April, 1997.     

Control of the aerodynamic characteristics of wing airfoils by nonstationary energy supply in transonic flow

The possibility of controlling the aerodynamic characteristics of wing airfoils in transonic regimes of flight using one-sided pulse-periodic energy supply has been studied. The flow structure near the symmetric airfoil at different angles of attack and its aerodynamic characteristics as functions of the value of energy in its nonsymmetric (about the airfoil) supply have been determined by numerical solution of two-dimensional nonstationary gasdynamic equations. A comparison of the obtained results and the data of calculation of flow past the airfoil at different angles of attack without energy supply has been made. It has been established that a prescribed lift can be obtained, using energy supply, with a much higher fineness ratio of the airfoil than that in the case of flow past it at an angle of attack. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 1, pp. 18–22, January–February, 2009.     

The temperature field of a medium due to an instantaneous concentrated force

The temperature field of an isotropic medium subjected to the action of an instantaneous concentrated force has been found. The temperature is determined as a solution of a coupled system of differential equations in an infinite space. A numerical analysis of the results obtained is made. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 5, pp. 989–993, September–October, 2008.     

Measurement of viscoplastic properties of a liquid in experiments with a torsion viscosimeter

The results of a numerical solution of the problem of vibrations of a torsion viscosimeter filled with an incompressible viscoplastic liquid are presented. It has been shown that in the vicinity of the rotation axis there appears a dead zone, whose boundary changes in the process of vibrations. The influence of plastic properties of the liquid on the characteristics of viscosimeter vibrations has been determined. A method for identifying viscoplastic properties by the observed parameters of vibrations is proposed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 1, pp. 124–127, January–February, 2007.     

Hydrodynamic theory of the “Struya” former-flowmeter

We have formulated the fundamentals of the hydrodynamic theory of the “Struya” former-flowmeter — a device for measuring the fluid flow rate and forming a homogeneous flow and a representative sample for subsequent qualitative analysis of the fluid medium composition. On the basis of the numerical solution of the Navier–Stokes equations, computer simulation of the flow of a viscous medium in the “Struya” former has been carried out. Models of homogeneous flow of a single incompressible fluid and of inhomogeneous flow of a two-phase dispersive fluid have been considered. Numerical calculations have confirmed the high characteristics of the “Struya” former which, as compared to the standard restrictions, has the lowest level of hydraulic losses and the highest accuracy of differential pressure formation. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 82, No. 2, pp. 308–319, March–April, 2009.     

Analytical solutions of hydromagnetic boundary-layer flow of a non-Newtonian power-law fluid past a continuously moving surface

Summary The boundary-layer flow of a power-law non–Newtonian fluid over a continuously moving surface in the presence of a magnetic field B(x) applied perpendicular to the surface has been investigated. An analytical solution is obtained and compared with the numerical solution of the resulting non linear ordinary differential equation. The effects of the Stewart number (N) and the power law-index (n) on the velocity profiles and the skin-friction are studied.     

Numerical simulation of laminar flow of oil and heat transfer near a circular cylinder with arched guide plates

We have investigated the intensification of the heat transfer from a cylinder in an oil medium due to the setting of arched guide plates on the basis of the numerical solution of the Navier-Stokes and energy equations with the help of multiblock computer-aided technologies realized in the VP2/3 package. Calculations have been made for the laminar nonstationary cross flow around a heated cylinder in a viscous medium with a strong temperature dependence of its thermophysical characteristics. Comparison has been made between the numerical forecasts of the drag, local heat transfer, thermohydraulic efficiency, and total Nusselt number for a cylinder with plates and for a single cylinder. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 4, pp. 705–711, July–August, 2008.     

Bilateral bending of a plate with nonsymmetric through-thickness arc crack with allowance for the contact of its edges

The problem of bending of plates with nonsymmetric through-thickness arc crack with distributed moments at infinity with allowance for the contact of the crack edges has been examined on the basis of the classical theory of plate bending. The conditions for the existence of the solution of the problem in this formulation have been established. A numerical analysis of intensity factors of forces and moments, contact force between the crack edges has been performed, the results of which have been graphically illustrated. __________ Translated from Problemy Prochnosti, No. 5, pp. 135–141, September–October, 2006. Report on International Conference “Dynamics, Strength, and Life of Machines and Structures” (1–4 November 2006, Kiev, Ukraine).     

Design of multimode axisymmetric hypersonic nozzles with the use of optimization methods

On the basis of the solution of direct problems with the use of various medium models and numerical methods of integration of gas flow equations, methods for designing super- and hypersonic nozzles have been developed. Multimode nozzles in the ranges of Mach numbers 8–14 and 14–20 satisfying given conditions have been designed.     

Numerical simulation of a viscous separation flow around a rotating circular cylinder

Results of numerical solution of Navier-Stokes equations in stream function-vortex variables for a nonstationary laminar flow around a circular cylinder with a rotational degree of freedom are presented. The cases of definite, free, and inertial rotation of the indicated cylinder were considered. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 3, pp. 75–81, May–June, 2006.     

Interaction of a combination of bodies in supersonic flow. Interference and diffraction of shock waves in flow over two bodies of revolution

Results are presented of numerical investigations of three-dimensional supersonic flows in a disturbed region of jointly streamlined two identical bodies arranged in parallel which represent combinations of a cone with a semivertex angle of 20° and a cylinder with a fineness ratio of 5. Longitudinal flow over bodies has been studied numerically based on the Euler equation at a Mach number of incident flow equal to 4.03 and a zero angle of attack. The effect has been shown of the distance between the axes of models on the flow structure and disturbed and total aerodynamic characteristics of bodies. Calculated results have been compared with data of the physical experiment. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 4, pp. 81–90, July–August, 2006.