Home – Home – Jornals – Thermophysics and Aeromechanics 2011 number 2

Development of cosmonautics and preparation to the first manned space flights are briefly observed. Details of the development of the first Soviet intercontinental ballistic missile R-7, which served as a basis for creating Sputnik, Vostok, Voskhod, Molniya, and Soyuz launchers, are given. The contributions of the outstanding designers of space engineering, W. von Braun, S.P. Korolev, V.P. Glushko, and academician M.V. Keldysh, to the development of astronautics and first manned space missions are demonstrated. A list of test launches and manned flights of Vostok and Mercury spacecrafts and the basic characteristics of Vostok, Redstone, Atlas-D, Voskhod, and Soyuz launchers are presented.

An investigation of aerodynamic performance for micro air vehicle (MAV) wing is performed. It is shown, what is a reason of significant wing performance difference between tests, which were carried out in different wind tunnels. New method for estimation of wind tunnel condition influence on experimental results is suggested.

Results of numerical investigation of the effect of heat boundary layer thickness in front of a sudden expansion of a round tube on turbulent transfer in the zone of flow separation, attachment, and relaxation are presented. Before separation the flow was hydrodynamically stable, and the heat layer in front of expansion could change its thickness in maximally possible limits: from zero to a half of tube diameter. The Reynolds number varied from 6.7∙10³ to 1.33∙10⁵. It was found that the growth of heat layer thickness leads to reduction of heat transfer intensity in the separation area and moving away of the coordinate of maximal heat transfer from the place of tube expansion. Generalizing dependence for the maximum Nusselt number is given for variation of the heat layer thickness. Comparison with experimental data of [1] proved the main behavior tendencies of heat and mass transfer processes in separation flows behind a backward-facing step with different thermal prehistory.

The stability of the Couette - Poiseuille flow of a monodisperse mixture is considered. Sufficient stability conditions are derived. Results of the computation of the spectrum are presented. A considerable stabilization of the flow with particles admixture to small disturbances is observed. It is found that the regions of instability generation may have complex geometry. The influence of the main velocity profile and admixture parameters on the stability conditions is considered.

On the basis of the previously developed asymptotic theory of turbulent particle-laden flow with particle deposition in channels coupled with the transport model for the particle Reynolds stress, an asymptotic solution to the problem on the deposition of particles in the limit of high Reynolds numbers was obtained. The numerical calculations confirmed the presence, in the region of the transition from the diffusion-impaction regime of particle sedimentation to the inertia-moderated regime, bifurcation phenomenon of a solution found previously in earlier studies. Features of particle accumulation in the viscous sublayer are analyzed. On the basis of the numerical solution, correlations for particle deposition velocity were obtained. Boundary conditions of the wall-function type for particle concentration whose use allows widening the applicability limits of the equilibrium Eulerian models in terms of particle inertia are proposed.

Laboratory samples of small-sized energy converters based on thermo-electric method of heat conversion which source is diffusion microflame are presented in the work. Processes of combustion, energy conversion, and cooling in the proposed systems have been experimentally studied. Relatively high efficiency of the studied systems (energy-conversion 0.8 % at generated electric power of 130 mW) complying with the current world level for such devices is shown. The advantages of the proposed power generators are absence of forced-cooling system and catalysts, assemblage simplicity and usage of available materials and components. On the basis of investigation results, possible ways of further improvement of test samples have been determined with the view of energy conversion efficiency increase.

Filtration and separation properties were studied for filters made from open-porosity ceramics (sintered from authors-developed silicon dioxide nanopowder tarkosil". Key parameters were measured for samples of ceramics produced at different sintering temperatures: porosity, gas permeability coefficient, relative time of standard volume fill-up, gas mixture separation coefficient. The possibility of using the described ceramics for helium enrichment was demonstrated with examples of helium-nitrogen and helium-methane mixtures.

The modification of electrodiffusional method of the wall shear stress measurements is applied for registration of the Taylor bubble shear stress in an upward liquid flow. Time realization of shear is considered as a structure frozen into the flow, which moves together with a bubble. Experiments were carried out in laminar and transitional liquid flows. The wall shear stress in the liquid film around bubble averaged over the tube perimeter is presented for different flow Reynolds numbers and different lengths of the bubble.

The thermal-diffusive model was applied to the problem of flame propagation in a microchannel with controlled temperature distribution in the walls; this demonstrated the possibility of formation of oscillating or rotating spatial flame structures, which were described previously in experimental works on microcombustion. Two cases were considered: combustion in a rectangular channel and in the clearance between two disks with radial feeding of premixture. In both cases, the typical across size of the channel was lower than the critical diameter determined with respect to the ambient temperature. The gas flow was assigned and described by the Poiseuille-flow velocity profile. Formation of oscillating flame in a rectangular channel and rotating patterns in a radial channel was observed for a certain range of gas flow rate. At low flow rates beyond this range, repetitive ignition/extinction of flame took place; at high flow rate we observed a steady flame mode. Formation of these special flame structures is related to heat transfer between gas and hot walls of the channel, as well as to velocity maldistribution in the microchannel.

Dependence of spectral and energy characteristics of cesium plasma radiation on electric power P_{L has been found. It is shown that with PL growth metal vapor pressure increases; transformation of spectral structure of radiation manifested in disappearance of individual lines and increase of steady monotone takes place. Redistribution of average radiation power in individual spectral ranges is observed.}

The paper presents the investigation of plasma melting of the mixed bottom and fly incineration ash at various mixing ratios of the components. Chemical compound of the bottom and fly ash as well as the slag after its melting was analyzed by different methods, and the content of toxic components in them was determined. It is demonstrated that the direct disposal of the fly and bottom incineration ash may cause dioxin and heavy metal contamination of the environment. The influence of melted ash basicity on the resulting slag compound was studied. The mass balance of the melting process was defined. The tests were performed to determine the heavy-metals leaching from the ash and slag. It is also shown that the slag after plasma melting is dioxin-free and environmentally friendly.

The work presents the results of cycle computation for vapor compression pumps based on ozone-safe mixed refrigerants. Non-azeotropic binary refrugerants R32/R152а (30/70) and R32/R134а (30/70) were considered as working substances. Properties of non-azeotropic refrigerants were calculated according to the additivity method of thermodynamic functions and method of Lemmon and Jacobsen. Deviations in the values of thermophysical properties obtained with two methods have been determined. It is shown that at the use of non-azeotropic mixture R32/R152a (30/70), energy conversion ratio increases by 2.2−3.6 % compared with the results for R32/R134a (30/70) at temperature difference between the processes of boiling and condensation from 28 to 53 °С.

On April 13, 2011 Chief researcher of Lavrentiev Institute of Hydrodynamics SB RAS, Doctor of Physics and Mathematics, Professor Vladimir B. Kurzin  was  80 years of age.