Том 54, № 4 (2016)

Low-temperature hydrogen plasma has been investigated under the conditions of electron cyclotron resonance by emission spectroscopy. The molecular distribution functions over the low rotational and vibrational levels of the hydrogen molecule in the d³Π_u^- triplet state have been measured. The translational, rotational, and vibrational temperatures of the ground and excited triplet states of the hydrogen molecule are determined. The obtained translational and vibrational temperatures indicate that low-temperature hydrogen plasma under the conditions of electron cyclotron resonance is a more efficient source of vibrationally excited hydrogen molecules in comparison with the other gas discharges.

The results of calculation of the chemical composition of plasma of the DC atmospheric pressure discharge in air in contact with aqueous solutions of sulfonol (C₁₂H₂₅C₆H₄SO₃Na) in the concentration range of 0–10 g/L at a discharge current of 40 mA are presented. At modeling, the combined solution of Boltzmann equation for the electron gas, equations of vibrational kinetics for ground states of N₂, O₂, H₂O, and NO molecules, equations of chemical kinetics and plasma conductivity equation were used. It was shown that sodium atoms appearing as a result of transfer processes from the liquid cathode affect the chemical composition of the plasma and the characteristics of the electron gas.

The integral emissivity of oxide materials at high temperatures are evaluated by means of the band model; its behavior is explained. A simplified model of the band structure at high temperatures is proposed, and the expression for the calculation of the relative population of the states under thermodynamic equilibrium is obtained. The urgency of the measurements of absorption and emission of oxide materials for the determination of the density-of-states distribution and the band structure of substances at high temperatures and melting is demonstrated.

The results of thermodynamic studies of the cobaltic manganites NdM₂^IICoMnO₆ (M^II is Mg, Ca, Sr, or Ba) are presented. In the calorimetric studies of the heat capacity within the range of 298.15–673 K, a second kind λ-shaped phase transitions in the C_p(T) dependences was discovered: at the temperatures of 373 and 523 K for NdMg₂CoMnO₆; at 348 and 498 K for NdCa₂CoMnO₆; at 423 and 548 K for NdSr₂CoMnO₆; and at 323 and 498 K for NdBa₂CoMnO₆. We derive the equations for the temperature dependence of the heat capacity with account for these phase transitions. We calculate the temperature dependences of the thermodynamic functions: entropy, S⁰(T), enthalpy, H⁰(T)–H⁰(298.15), and the reduced thermodynamic potential, Φ^xx(T), of the studied manganites.

The results of experimental studies of heat removal from convex and concave heating surfaces of annular channels with swirl and transit flow in the precrisis region are presented. The dependences describing the data on the heat removal rate from convex and concave heating surfaces are given.

The effect of quantum corrections to the rate constants of chemical reactions on the time of thermal ignition of hydrogen-containing mixtures is studied. It is shown that, at high pressures (30–100) atm and temperatures in the range of (700–900) K, accounting for the quantum corrections to the initiation reaction H₂ + O₂ → 2OH brings the data on the calculated ignition delay times of the hydrogen-containing mixture into agreement with the previously published results of measurements.

The results of numerical simulation of transonic cross flow of a perfect gas around a circular cylinder at high Reynolds numbers are used to solve the thermal problem. The temperature distributions along the central line and the influence of Reynolds and Mach numbers on them are presented. The temperature fields and the transition of the near-wake solution to the far-wake solution are studied.

This paper presents an original method for formation of an operating area of investigations of the electrophysical characteristics of the high-temperature electrode insulation of units of transmission electrogenerating channels within cesium vapors on the base of the same unit under investigation, which eliminates the appearance of spurious discharges and enhances the measuring accuracy. The authoring configuration of experimental specimens additionally provides the possibility to control the interlaminar hermiticity of the ceramic–metal composition, which reflects the quality of the diffusion connection of the ceramic and metallic layers. Results of experimental investigation of the electric resistance and the breakdown voltage of the insulating layer in vacuum, cesium vapor, and cesium plasma are given for specimens of the ceramic–metal composition in the SB1 alloy (Nb + 1% Zr)–Al₂O₃ (0.3 mm)–SB1 alloy (Nb + 1% Zr) system.

The operating conditions of gas-distribution stations located on gas-main pipelines are analyzed. It is shown that there is a technological pressure difference in natural gas at most stations, which can be used for liquefaction of natural gases. The data of the numerical investigation, demonstrating that it is possible to abandon the use of flame heaters of reduced natural gas due to the use of the gasdynamic energy separation effect by simultaneously cooling the natural gas going to liquefaction, are given. This technique can be applied on a quarter of all gas-distribution stations of the Russian Federation (about 1000 stations).

A short survey of the available knowledge on heat transfer of gaseous heat carriers with variable physical properties (gases and their mixtures, in particular, those catalytically reacting on a wall, high pressure vapor, as well as single-phase supercritical pressure heat carriers) to turbulent flows upon intense heating in tubes is presented. The problem of heat transfer deterioration under high heat loads (in particular, in the context of flow laminarization) is discussed. The existing knowledge about the nature of these phenomena and methods for their prediction are considered. The empirical relationships for estimating the temperature regime of the wall under conditions of normal and deteriorated heat transfer are presented. The consequences of the transition to new standards in properties of supercritical pressure heat carriers are shown from the viewpoint of accuracy in the engineering analysis of heat transfer by the existing methods. Ways of rehabilitation for old empirical formulas are proposed for the case of using new standards of thermophysical properties.

Streamlining of a circular cylinder with a localized heat source modeling an MHD actuator in which the plasma arc channel moves along the cylinder surface under the action of the Lorentz force in a radial magnetic field is studied experimentally and simulated numerically. It is shown that the presence of a moving heat release region leads to a break in the symmetry in cylinder streamlining by the external flow and the appearance of a nonzero lift force and circulation.

The cavitation rupture strength of liquid is studied by the molecular dynamics methods for simple materials by the example of argon in the presence of neon. Results on negative rupture pressure are obtained for different concentrations of the gas dissolved in the system. A linear dependence between these parameters is established.