Vol 61, No 6 (2023)

This year marks 60 years since publication of the first issue of High Temperature. During this time, one of the main sections of the journal has been devoted to research in the fields of heat and mass transfer and physical gas dynamics.

Clusters of active Brownian particles in gas-discharge plasma are considered as open systems with energy exchange with the environment. The evolution of a cluster of 19 active Brownian particles with a partially absorbing metal surface (so-called Janus particles) when exposed to intense laser radiation is shown. The formation of strongly correlated clusters of charged particles with increasing laser radiation power was observed experimentally. Based on an analysis of the trajectories of particles, the region of their localization, and changes in their kinetic energy, fractal dimension, and dynamic entropy for different values of laser radiation power density, the self-organization of a cluster of strongly interacting particles in the plasma of a high-frequency glow discharge is studied.

The study considers a two-component electroneutral equilibrium complex plasma of finite-sized macroions with charges Z (Z 
 1) and point oppositely charged microions with unit charges. System pressure was calculated in the Poisson–Boltzmann approximation with regard to nonlinear screening of macroions by microions in the average Wigner–Seitz cell model. One of the calculation methods obtains pressure by calculating the nonideal part of the Helmholtz free energy; the second is specific to the Wigner–Seitz average cell model. It is shown that the pressure and isothermal compressibility of the plasma are positive over the entire range of macroion concentrations.

The correlation dependence of thermal conductivity 
 of liquid refrigerants on the saturation line is developed as a simple function of temperature 
: 
 (where 
 is the criterion unit, 
, and 
 is the critical temperature). This dependence satisfies the requirements of dynamic scale theory (ST), and in particular, the passage to the limit 
. The proposed correlation dependence is tested using the example of describing the thermal conductivity of 17 liquid substances in the range of state parameters from the saturation line to the critical pressure 
 and in the temperature range from the triple point temperature Ttr to 
. The substances reviewed include nine fourth-generation refrigerants of hydrofluorochloro derivatives of olefins, seven hydrochlorofluorocarbons and hydrofluorocarbons, and C3H8. Using the description of 
 of C3H8 as an example, it is shown that the proposed correlation dependence not only qualitatively but also quantitatively accurately conveys the behavior of 
 in the vicinity of the critical point. Based on the statistical analysis, it is shown that the proposed correlation with significantly less uncertainty describes the data on the thermal conductivity of liquid hydrofluorochloro derivatives of olefins both on the saturation line and in the single-phase region. Based on the proposed methodology, the thermal conductivity of the cis-isomer R1225ye(Z) is calculated for the first time in the temperature range 

High-temperature differential mass spectrometry was used to study the vaporization processes and thermodynamic properties of samples of the Fe2O3–TiO2 system containing 25, 35, and 45 mol. % iron oxide. As shown earlier, at temperatures above 1400 K, Fe2O3, losing oxygen, turns into FeO. Therefore, in this article, a mass spectrometric thermodynamic study of the FeO–TiO2 system was carried out at a temperature of 1760 K. The composition and partial pressures of vapor, as well as the values of FeO activities and excess Gibbs energy in the FeO–TiO2 system were determined. Using the Wilson polynomial made it possible for the first time to estimate the mixing enthalpy and excess entropy in the FeO–TiO2 system at 1760 K. The thermodynamic properties of melts of the FeO–TiO2 system at 1760 K were modeled using the generalized lattice theory of associated solutions, and the relative numbers of bonds of various types in the model melt lattice were calculated, indicating the preferential formation of Fe–O–Ti bonds at a FeO content of 55 mol %. It is shown that at a temperature of 1760 K, the found values of the excess Gibbs energy in the FeO–TiO2 system are evidence of negative deviations from the ideality.

In the present paper, we calculated the elastic, mechanical, and thermophysical properties of NbN/MgO(001) layers in the temperature range 600–900°C using higher order elastic constants. With two fundamental factors, nearest-neighbour distance as well as hardness parameter, the second and third order elastic constants are estimated using the Born–Mayer potential approaches. The computed values of second order elastic constant are used to calculate Young modulus, thermal conductivity, Zener anisotropy, bulk modulus, thermal energy density, shear modulus as well as Poisson ratio in order to assess the thermal and mechanical properties of NbN/MgO(001) layers. Additionally, the second order elastic constant is also used to calculate the wave velocities for shear and longitudinal modes of propagation along crystalline orientations [100], [110], [111]. Temperature dependent Debye average velocity, hardness, and ultrasonic Grüneisen parameters are evaluated. The fracture/toughness B/G ratio in the current investigation is more than 1.75, indicating that the NbN/MgO(001) nanostructured layer is ductile in nature in this temperature range. The selected materials are fully satisfying the Born mechanical stability requirement. The time required for thermal relaxation is calculated and how ultrasonic waves are attenuated by thermo-elastic relaxation and phonon–phonon interaction mechanisms. The findings with other well-known physical features are helpful for industrial applications.

The paper presents the results of a numerical study of the interaction of detonation waves with counterpropagating pressure waves in a bubbly liquid. The change in the parameters of a detonation wave as it passes through the front of a counterpropagating pressure wave is analyzed. The possibility of controlling propagation of the detonation process by changing the state of the bubble system by counterpropagating pressure waves is studied.

The influence of preliminary ionization and excitation of molecules of a fuel–air mixture when exposed to an electron beam created in an external electric field on increasing the intensity of combustion processes is considered. To study the effect of electron beam plasma on the combustion of a propane–air mixture, a series of experiments were carried out. The characteristics of the propane–air mixture are determined before and after irradiation with an electron beam in the presence and absence of an external electric field. The boundaries of the combined effect of an electron beam and an external electric field are found to increase the efficiency of combustion of a propane–air mixture in a subsonic flow. A physical model of processes in a non-self-sustaining discharge in a subsonic flow of a combustible mixture under known experimental conditions is developed.

The study examines aspects of the generation of the second optical harmonic in the centrosymmetric antiferromagnet NiO when exposed to narrowband terahertz pulses with an electric field strength on the order of 1 MV/cm. It was found that when exposed to terahertz pulses with a frequency of 1 THz, which corresponds to the antiferromagnetic resonance frequency of NiO, a significant decrease in the intensity of the second harmonic is observed versus exposure to pulses with a frequency of 1.5 THz. It is shown that the observed decrease in the intensity of second harmonic generation can be explained by multipath interference during the propagation of a narrowband terahertz pulse in a thin sample.

The main problems and features of the study of two-phase flows are considered. The main methods for the mathematical modeling of two-phase flows, which describe the interface boundary, interface interactions, and turbulence of the carrier phase at different hierarchical levels, are briefly described. Some of the latest research results on two-phase flows with solid particles, droplets, and bubbles are described and analyzed: effective methods of thermal protection of power propulsion systems operating on solid fuels; determining the contribution of carbon nanoparticle condensation to the combustion and detonation of gaseous hydrocarbons; aircraft anti-icing methods; specific features of the development and stability of a spray plume; acoustic wave propagation in multifractional polydisperse vapor–gas–droplet mixtures of gas with solid particles; development of detonation waves in a bubbly liquid; and many others.

The melting temperature of zirconium was measured at different pressures in the range from 1 to 4000 bar by pulsed current heating. The obtained pressure dependence of the melting temperature gives an estimate of the slope of the zirconium melting line of 62 K/GPa, which agrees well with the results of ab initio calculations.

A mathematical model of nonisothermal filtration of a fluid into a medium with double porosity is constructed. The influence of the filtration and thermophysical parameters of a fractured porous formation on the temperature and pressure in the bottom of a vertical oil well due to production is studied. Based on the proposed model, a computational algorithm for interpreting the results of the thermohydrodynamic studies of vertical wells is developed. Measurements of the pressure and temperature in the bottom of the well after its start-up are used as the initial information.