Heat exchange between a selectively emitting liquid and a laminar gas flow in the presence of an external source of radiation

An investigation is conducted in the solution of a number of practical problems of the radiative and combined heat exchange in nonuniform systems having widely different physical properties. The processes of thermal interaction between the ocean and the atmosphere have been treated in the paper [1], the effect of thermal radiation on the melting and solidification of semitransparent crystals has been investigated in [2], the flow of a selectively emitting gas around the lateral surface of an object evaporating under the action of radiative heating has been discussed in [3], and heat transfer from a jet to the molten mass of glass in a glassmaking furnace tank has been investigated in [4]. The radiative and combined heat exchange between a selectively emitting liquid and a transparent heat-conducting laminar gas flow in the case of a specified external thermal radiation field is discussed in this paper. The energy conservation equations are set up taking into account the heat transfer by radiation, convection, and molecular thermal conduction. A differential approximation is used in calculating the values of the radiation fluxes. A system of fundamental computational equations is solved by the method of finite differences and iterations and by the Runge-Kutta method. The results of the calculations are presented in the form of graphs.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 116–122, May–June, 1976.     

Kinetics of the thermal decomposition of dinitramide

The kinetic regularities of the thermal decomposition of dinitramide in aqueous solutions of HNO₃, in anhydrous acetic acid, and in several other organic solvents were studied. The rate of the decomposition of dinitramide in aqueous HNO₃ is determined by the decomposition of mixed anhydride of dinitramide and nitric acid (N₄O₆) formed in the solution in the reversible reaction. The decomposition of the anhydride is a reason for an increase in the decomposition rates of dinitramide in solutions of HNO₃ as compared to those in solutions in H₂SO₄ and the self-acceleration of the process in concentrated aqueous solutions of dinitramide. The increase in the decomposition rate of nondissociated dinitramide compared to the decomposition rate of the N(NO₂)₂ ⁻ anion is explained by a decrease in the order of the N−NO₂ bond. The increase in the rate constant of the decomposition of the protonated form of dinitramide compared to the corresponding value for neutral molecules is due to the dehydration mechanism of the reaction. For Part 1, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 41–47, January, 1998.     

Mn site substitution of La0.67Ca0.33MnO3 with closed shell ions: Effect on magnetic transition temperature

Mn site is substituted with closed shell ions (Al, Ga, Ti, Zr and a certain combination of Zr and Al) and also with Fe and Ru ions carrying the magnetic moment (S=5/2 and 2 respectively) at a fixed concentration of 5 at %. Substitution did not change either the crystal symmetry or the oxygen stoichiometry. All substituents were found to suppress both the metal-insulator and ferromagnetic transition temperatures (T _p(ρ) and T _C, respectively) to varied extents. Two main contributions identified for the suppression are the lattice disorder arising due to difference in the ionic radii between the substituent (r _M) and the Mn³⁺ ion (r _Mn ³⁺) and in the case of the substituents carrying a magnetic moment, the type of magnetic coupling between the substituent and that of the neighboring Mn ion.     

Deformation of liquid line with the collision of jets

With the study of the collision of metallic plates accelerated by an explosion, investigation of plastic deformations in the collision zone is of great importance. In [1] a method is expounded for investigations of deformation with explosion welding under conditions of wave formation; the method consists of the pressing of a thin wire into the metallic plate. With collision of the plates, the flowing metal carries the wire with it; the change in the form of the latter makes it possible to evaluate the character of the plastic deformation in the collision zone. From an investigation of the deformation of the wires, such important characteristics as the viscosity of the metals can be found. The method set forth in [1] is one of the few means of investigating the deformation of metals with high-speed collisions. The difficulties in the investigation are bound up with the small times of the process and with the high pressures, developing with an explosion and demolishing the experimental unit. In [1], from an analysis of viscous flow during the collision of plates, a dependence of the shift on the distance to the interface between the materials, described by a parabola, is derived. It is noted that, near the interface, the theoretical and experimental results differ considerably. It is important to make an attempt at a theoretical analysis of the wire deformation if, with the collision of metallic plates, a jet is formed and the interface between the materials is even. In this case, the flow differs strongly from the flow under conditions of wave formation [2], and near the interface the flow cannot be described by a parabolic dependence; this dependence will probably be exponential. To describe flow with the formation of a jet, in [3] a model of an ideal liquid is employed. Since the analysis of a collision between viscous jets with a free boundary is bound up with serious difficulties, in the first approximation it is advisable to consider the deformation of the liquid line with the deformation of ideal jets.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 6, pp. 65–71, November–December, 1977.The author wishes to express his thanks to N. S. Kozin and V. V. Efremov for a number of valuable observations with an evaluation of the work, and N. M. Maksimova for her aid in making the numerical calculation.     

Radiative-Convective Heat Transfer in Discharge Chamber at Turbulent Gas Flow

In the paper radiative-convective heat transfer in electric arc flowed through by Ar in the discharge chamber is studied. The equation system for heat, mass and momentum transfer in boundary layer approximation is considered, and the turbulence model with radiation pulsation and electrodynamic values is suggested. By solution of the equation system with the help of finite differences method distributions of temperature, heat flows and turbulent transfer coefficients over chamber length were obtained. The radiation and turbulence influence on the electric arc characteristics is analysed.     

Nonstationary reaction of a thin-walled cylindrical shell in a fluid subjected to a concentrated impulsive force

Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Prikladnaya Mekhanika, Vol. 25, No. 4, pp. 39–46, April, 1989.     

Attempt to perform bistatic radio location of the sun using Venera-16

Radiophysics and Quantum Electronics -