Home – Home – Jornals – Thermophysics and Aeromechanics 2014 number 3

July 18, 2014 is the 100 year Anniversary of the out-standing scientist, Hero of Socialist Labor, Academician Samson S. Kutateladze. He made an inva-luable contribution to the development of the science of heat and mass transfer. The personality of Samson Kutateladze was inseparably connected with the history of thermophysics development.

The hydrodynamic processes occurring at injection of cryogenic liquid into water pool were studied experimentally. Processes accompanying the phase transitions were registered. Data testify the developing pressure burst with an amplitude sufficient for possible formation of gas hydrates when methane is injected as a cryogenic fluid.

The article provides statistical data on the characteristics of subcooled liquid boiling and behavior of vapor and air bubbles resulted from high-speed shooting. The authors have described a number of new phenomena going along with water boiling.

The structure of gas-droplet polydisperse jet was studied experimentally and numerically. Experiments were carried out using the Particle Image Velocimetry/Particle Tracking Velocimetry/Interferometric Particle Imaging methods, which allowed simultaneous measurements of parameters for the average and pulsation carrying and disperse phases. Gas phase turbulence was calculated using the model of Reynolds stresses transfer. Significantly non-isotropic character of velocity pulsation of particles along and across the section of the gas-droplet jet was demonstrated in experiments and calculations. Strong dependence of axial pulsations of disperse phase velocity on the size of its particles is observed.

Results of laboratory research and numerical simulation of 3D separated channel flow behind a semi-cylindrical spanwise rib in laminar and transitional to turbulence flow regimes are presented. Data on dynamics of flow structure and evolution of large-scale vortical structures generated in the obstacle wake zone have been obtained.

The wavy downflow of a viscous liquid film in the presence of the turbulent gas flow was analyzed theoretically. Two-dimensional stationary running waves are calculated in a wide range of Reynolds numbers of liquid and gas. Hydrodynamics of liquid is calculated based on complete Navier-Stokes equations. The wave interface surface is considered as a small perturbation and equations in gas are linearized near the main turbulent flow. Different optimal downflow regimes are determined, and the main wave characteristics are compared in detail with and without the co- and counter-current gas flows. It is shown that at high velocities of the co-current gas flow, the calculated waves correspond to ripples observed in experiments.

The paper studies the process of floating a gas hydrate particle in liquid. The typical depths when gas bubble floating is accompanied by gas hydrate formation (or with zero gain of hydrate) were calculated. The low depths were identified when floating occurs with hydrate dissociation. The model assumes that the gas hydrate formation is limited by heat transfer from interface to the surrounding liquid. The model for gas hydrate dissociation assumes the rate governed by thermal conductivity of hydrate particle and by convective heat transfer to surrounding water. The temperature of the gas hydrate surface equals the phase transition temperature at the given water pressure. Comparative analysis of thermal conductivity and convective heat transfer effects on hydrate dissociation rate was performed for different initial radius of the particle.

Interdiffusion in potassium-lead melts containing 30, 40, 50, 66.7, and 84.4 at. % Pb was investigated using gamma-ray attenuation technique in the temperature range from 550 to 970 K. It was found that the concentration dependence of interdiffusion coefficient has a maximum in the vicinity of 40–50 at. % Pb. It was shown that this feature is associated with the trend of forming ionic complexes of K₄Pb₄ in liquid alloys.

A mathematical model is proposed for the process of modifying the metal surface layer by refractory nano-size particles with the aid of the pulse laser radiation, which accounts for the surface tension dependence on the presence of surface-active substance in the melt. Numerical modeling has been carried out, from the results of which the influence of the surface –active admixture on the character of forming flows, distribution of particles of the modifying substance in the metal, and the melt crystallization process have been estimated.

Present work analyzes the flow hydrodynamics and mass transfer mechanisms in double Rushton and CD–6 impeller on wide range (0.0075–0.25 m/s) of superficial gas velocity (ν_g) in a gas-liquid phase bioreactor by employing computational fluid dynamics (CFD) technique. The volume averaged velocity magnitude and dissipation rate are found higher with increasing superficial gas velocity. Higher relative power draw (P_g/P₀) is predicted in CD–6 than the Rushton impeller but no significant difference in volume averaged mass transfer coefficient (kLa) observed between these two types of impeller. The ratio of power draw with mass transfer coefficient has been found higher in CD-6 impeller (25–50 %) than the Rushton impeller.

In the present paper, we evaluate the effectiveness of the coordinated solution to the optimization problem for the parameters of cycles in gas turbine and combined cycle power plants and to the optimization problem for the gas-turbine flow path parameters within an integral complex problem. We report comparative data for optimizations of the combined cycle power plant at coordinated and separate optimizations, when, first, the gas turbine and, then, the steam part of a combined cycle plant is optimized. The comparative data are presented in terms of economic indicators, energy-effectiveness characteristics, and specific costs. Models that were used in the present study for calculating the flow path enable taking into account, as a factor influencing the economic and energy effectiveness of the power plant, the heat stability of alloys from which the nozzle and rotor blades of gas-turbine stages are made.

The lab-scale burner device with proprietary design was used for combustion of diesel fuel in a steam-enhanced regime. This operation mode ensures drastic intensification of liquid hydrocarbon combustion due to supply of superheated steam jet to the combustion zone. The particle image velocimetry technique was used for study of velocity field in the burner flame. The method of seeding of flow zone with new kind of tracers (micro-sized silica particles produced from silicon oil added to liquid fuel) was tested.

Combustion of n-butanol was studied experimentally at the two-phase flow in a rectangular channel of 4-mm height. Characteristics of the two-phase flow in channels with close configuration were analyzed, and the conditions of flame spread in the channel were determined. The dependencies of flame propagation velocity on flow velocity of the gas mixture with different oxygen contents were measured.