Home – Home – Jornals – Thermophysics and Aeromechanics 2005 number 3

The experiments on visualization of complex flows in a wind tunnel and water channel have been conducted. The structures of wake, separation, and laminar-turbulent transition were determined and investigated in a separated boundary layer downstream of a sphere for Reynolds numbers from 22

A technique is proposed for computation of gas dynamic parameters in a shock layer at a flow around an oscillating axisymmetric body of revolution with generatrix breaks under conditions of an intense surface mass exchange. The numerical computations using the developed technique were carried out to estimate the influence of the Mach number and the mass exchange intensity on the flow around a body with complex geometric shape. The dependencies are obtained, which enable the determination of the time of the velocity and pressure decay in a shock layer near the design angle of attack.

A method for the solution of problems of optimizing the shapes of cascades of blades is developed and applied, which is termed the gradient-variation method and based on calculation of a gradient of the optimization problem functional using the values of flow parameter variations in the design variables determined from the system of gas dynamics equations in variations. A test comparison of its efficiency with a similar (gradient) method in which a functional gradient is computed by finite differences at the solution of specific problems of the optimization of cascades of blades was performed. A considerable acceleration of the process of searching for extremum was obtained. Numerical and graphical results of solving the problems of the shape optimization of blade cascades are presented.

A direct numerical simulation of a fully developed turbulent channel flow is carried out. A control volume method on a nonuniform grid and the high-resolution schemes in time and space are used to solve the full Navier

Results are reported of an experimental study of characteristics of a wave field generated in the test section of a wind tunnel by a piezoceramic source and an obliquely cut gasdynamic whistle located, respectively, in the stilling chamber of the nozzle and at the nozzle exit.

Calculation was carried out for phase velocity and deformation wave decay in a layer of viscoelastic material fixed tightly on the solid substrate. The inner structure of the wave was analyzed

The unsteady free convection flow past an isothermal vertical plate with constant mass flux is dealt with. The governing partial differential equations are transformed into a set of dimensionless equations, which are solved numerically using a finite-difference method. The dimensionless governing equations are unsteady, two-dimensional, coupled, and non-linear. Many results are obtained and a representative set of these results is displayed graphically to illustrate the influence of the various physical parameters on the local and average skin friction, Nusselt number and Sherwood number are also displayed graphically.

The features of interaction of a heterogeneous flow with obstacles are considered for different conditions; they result either in obstacle material erosion or build-up of a coating on the obstacle surface. The impact interaction between the heterogeneous flow and the obstacle at the particle velocity about 1000

The influence of thermal properties of filtrating liquids and gravitational forces on the counterflow impregnation process is investigated with the aid of mathematical modelling. Two variants of conditions under which such processes may arise in oil pools are considered.

A numerical simulation method was applied for study of vapor bubble dynamics; this bubble grows in uniformly superheated liquid at the superheat limit. The model of temperature-uniform equilibrium vapor bubble was applied; the model takes into account a time dependency in vapor pressure and density inside the bubble. These computations were compared with the available theoretical models and experimental results. The observed high velocity of bubble surface in experiments on explosive boiling of the liquid may be explained by a prolonged dynamic stage: during this stage a considerable pressure difference is sustained between the liquid and vapor bubble.

The pressure of saturated vapor and gaseous density of ternary ozone-free C10M1 refrigerant were measured at the lines of phase equilibrium by isochoric piezometer method over the temperature range of 310 403 K at pressures from dew line to 3

The known models used to describe the crystallization from the evaporating liquid disperse phase of the solution aerosol consider only one of the features of such processes: either the solvent (water) evaporation or the growth of the dissolved substance crystals. It is possible to take into account a relation between these processes with the aid of the equations for material balance of the solvent and the dissolved substance. The mechanisms of exchange processes are assumed to be known. Then a model is obtained, which enables a concurrent computation of the air humidity, the dissolved substance concentration, the sizes of the crystal and the droplet at any moment of time. The model application is illustrated by the example of a computation of the evaporation dynamics of a droplet of the kitchen salt solution. The times of the crystal birth and the complete solvent evaporation are computed for the given initial conditions.

Radiant boundary conditions used by the method of mid-fluxes are analyzed in respect to solution of one-phase Stefan problem in a layer of semitransparent material. Non-absorbing, absolutely absorbing, and combined (absorbing, transmitting, and reflecting) properties of the layer boundaries are considered in the framework of the gray and selective models as well as their connection with phase transformations.

One-phase Stefan problem was numerically simulated in a semitransparent layer with boundaries transparent for radiation. It is shown that at low temperatures of a medium to the right of a sample, convection plays a determining role, and at high temperatures, radiation is the most important factor. Since there is no absorption at the layer boundaries, a plate is heated faster and fusion processes become slower.

Some peculiarities of the computation of electric arc characteristics in a multiply connected region on the basis of the method of fictitious domains are considered. The use of the model of a local thermodynamic equilibrium of plasma is shown to be invalid within the framework of the above method, and the absence of regularization at the computation of electric current flow leads to the appearance of anomalous results.

The results of computation of an electric arc with an annular attachment on the external lateral surface of the cylindrical cathode are presented. The influence of the current and the inter-electrode distance on the arc characteristics and thermal effect of the arc on the anode surface are considered.

An algorithm is proposed for solving the problem of refining the drag coefficients in complex hydraulic nets in the presence of pressure probes in some intervals of the net. The algorithm enables the determination of the drag of net intervals at least for problems of small dimension. To find the drag coefficients in hydraulic nets with several hundreds of intervals and more an algorithm is required for solving large ill-conditioned systems of linear equations. One can also replace the system intervals with equivalent simpler intervals, thereby reducing concurrently the problem dimension and making the system of equations better conditioned.

26 June 2005 is the 70th anniversary of Vladimir E. Nakoryakov, the eminent Russian scholar in the field of thermal physics, the Full Member of the Russian Academy of Sciences. On behalf of numerous friends and colleagues, we wish Vladimir Nakoryakov sound health and many more years of creative work.

Professor Oleg Nikolaevich Lebedev, ex-Chancellor of the Novosibirsk State Academy of Waterborne Traffic, Honored Worker of Science and Technology, the Full Member of the Russian Academy of Natural Sciences, Doctor of Technical Sciences died on July 3, 2005 at age of 76.