Home – Home – Jornals – Thermophysics and Aeromechanics 2007 number 3

The paper described the creative path of K.E. Tsiolkovsky, the founder of theoretical cosmonautics, who devoted his life to solving various problems in the field of aerodynamics and rocket engineering, creating dirigibles with a metallic shell, jet planes, and air-cushioned trains, and studying the origin of planets, the Sun, and the Universe. The main engineering proposals of a scientist of great originality, which found applications in modern rocket and space engineering, are briefly analysed. The versatility of his interests is demonstrated; his research is shown to deal with many fields of science and technology, including the kinetic theory of gases, geology, cosmology, biology, philosophy, sociology, theology, and language science.

The results of experimental study of a nonlinear varicose instability of the streaky structure generated by roughness element in unswept-wing boundary layer are presented. Features of the varicose breakdown of longitudinal steady streaky structure such as modulation of structure in transverse and streamwise directions by secondary disturbance, occurrence of the new streaky structures and L -structures downstream are shown. Spatio-temporal pictures of the hot-wire visualization of flow during spatial evolution of the streaky structures under influence of secondary high-frequency disturbance are discussed. Features of the adverse pressure gradient influence upon processes of the nonlinear varicose instability evolution and flow structure are revealed. Essential influence of the adverse pressure gradient on evolution of disturbances is shown. Comparison of varicose instability of the streaky structures generated in two different ways (the roughness element as in the given work, and continuous air blowing as in the earlier published work) is the carried out.

The main characteristics of an acoustic resonance developing in a channel flow past flat bluff bodies with different trailing-edge shapes have been experimentally examined. It is shown that the range of flow velocities at which the resonance is observed is wider for a model with sharp trailing edge compared to a plate with blunt trailing edge.

The behavior of the velocity vorticity vector on a discontinuity surface arising in the supersonic non-uniform flow of combustible gas around a body with the formation of a shock or detonation wave is studied. The free stream is generally vortical and has a given distribution of parameters. The formulas are obtained for the vorticity vector components in a special coordinate system related to the wave. It is shown that in this case the vorticity vector normal to the wave remains continuous across the discontinuity surface, and in the case of axisymmetric flows, also the quantity remains continuous, which is equal to the ratio of the tangent vorticity component to density, although the quantities themselves taken separately undergo a discontinuity.

A self-similar solution is obtained for a one-dimensional problem of diffusion mixing of vapor and gas, which is followed by condensation process. Two limiting cases of mixing are considered: in the first one, the vapor and gas occupy in their initial states the volumes of semi-infinite extension, in the second case, the vapor has a semi-infinite extension, and constant values of temperature and gas concentration are maintained at its boundary. The peculiarities of the temperature and concentration fields are analysed versus the vapor and gas temperatures, and the temperature values are found, at which the mixing occurs with the condensate formation.

The paper presents the developed physical and mathematical models, calculation procedure based on finite-element method, and also the software for the numerical studying the processes of the non-stationary conjugate heat exchange and phase transition during the surface processing with high-concentrated energy fluxes with stationary, pulse, and movable heat sources (fusing of coatings, surface layer quenching, surface cleaning, etc.). The proposed and realized method permits to study the processes within a wide range of the power density of external heat fluxes qÎ [ 10⁷; 10^14] W/m² with significantly different spatial and temporal scales. The results presented are of interest for understanding and simulation of the processes occurring at the surface processing of the coatings and materials with high-concentrated energy fluxes.

Results of experimental studies on the local characteristics of heat transfer from a lead heat carrier to the surface of a cooled tube in an annular gap are shown at control and alteration of oxygen admixture content under the conditions of power circuits with heavy liquid-metal heat-transfer agent. This work is aimed at obtaining the grounded formulas for engineering calculations of heat transfer surfaces. Investigations were carried out at the lead temperature of 400- 500

Chemical transformations at incomplete methane oxidation in the air medium were studied experimentally at reaction activation on the wall of an annular microchannel. Methane was oxidized incompletely on a rhodium catalyst deposited on an inner wall of the channel. Concentrations of the products of chemical transformations were measured in the outlet gas mixture for different reactor temperatures and stay times. We have determined the range of channel wall temperatures and stay times of the mixture corresponding to an increase in the portion of hydrogen and carbon dioxide indicating transition from predominant methane combustion to cascade chemical reactions with activation of steam and carbon dioxide methane conversions. It is shown that the kinetic model of chemical transformations of methane in the air medium depends significantly on the temperature of channel walls and stay time of the mixture. The effect of outer diffusion deceleration on the rate of chemical transformations at incomplete methane oxidation under the strained conditions is determined.

Results of experimental studies of low-frequency acoustics of gas-liquid bubble media aimed at the check-up of the theory of resonance dispersion of sound of a new type are presented. According to the theory, together with well-known high-frequency dispersion of sound in the gas-liquid media, connected with resonance of volumetric bubble oscillations and, respectively, with resonance compressibility, there should be low-frequency resonance dispersion of sound caused by resonance of related spheroidal-progressive bubble oscillations and, correspondingly, by resonance of the efficient dynamic density of a medium. It is shown that experimental data on the velocity and attenuation coefficient of sound in the bubble media prove the existence of resonance dispersion caused by related progressive-deformation oscillations of bubbles.

The stationary modes of the end-face tube electrodes operation are under consideration. The formation of cathode and anode jets which cause dramatic increase in the electrode erosion at the arc current growth has been explained. We have considered the ways to increase the life-time of the continuous operation of tube electrodes. The analysis of the thermophysical interaction of the arc spot and electrode surface has enabled us to choose the optimum metal for the electrode.

The AC plasma electric furnace with graphite electrodes was tested using methane as the modelling gas. Its advantage for production of hydrogen and fine soot was demonstrated. It was found that 1150- 1200

Conversion of coals with various degrees of metamorphism in supercritical water (SCW) was studied under the isochoric conditions at the temperatures of 380- 800

A technique is developed for optimal control of dynamic processes in boiler aggregate based on the nonlinear mathematical programming and its program implementation is conducted. A comparison is presented for the regulation of dynamic process of the loading variation of the TP-81 boiler on the basis of the given technique and while using the conventional proportional-integral-differential regulators.

4 August, 2007  is the 60th anniversary of Prof. Amir A. Gubaidullin, the well-known scientist, Doctor of the Phisical and Mathematical Sciences. The entire life of A.A. Gubaidullin shows his aspiration for cognition, devotion to science, remarkable talent, and  honesty.