The results of the development and testing of copper-water loop heat pipes with flat-oval and flat disk-shaped evaporators are presented. The active zones of the evaporators are 27 and 26.5 cm2, respectively. The devices were tested in a horizontal position with a heat source having a heating surface of 16 cm2. A flat flow heat exchanger was used as a heat sink, through which water was pumped at a temperature of 40°C. At a maximum heat load of 900 W, loop heat pipes with a flat-oval evaporator showed a thermal resistance of 0.036°C/W. For loop heat pipes with a disk-shaped evaporator, these values were 800 W and 0.054°C/W, respectively. The devices can be effectively used in cooling systems for objects with a heating surface up to 30 cm2, dissipating up to 230–520 W at a maximum temperature of 70–90°C. Examples of the use of loop heat pipes in such systems are presented.

The effect of the size and structure of soot particles synthesized during combustion in a flat premixed flame of hydrocarbons and during pyrolysis behind shock waves on their optical properties is analyzed. Experiments are conducted to measure the optical properties and structure of soot particles in a propylene–air flame and during the pyrolysis of mixtures of 3% of acetylene, 5% of ethylene, and 2% of propylene in argon behind shock waves in an shock tube. The function of the refractive index of soot particles and its change in the visible and near-IR spectral ranges are obtained using the laser-induced incandescence method. The mean soot particle sizes and parameters of the internal structure of soot particles are measured using transmission electron microscopy. Based on the analysis of the results obtained in this study and those available in the literature, it is found that, as the size of soot particles increases, the refractive index function for them at a wavelength of 1064 nm increases by a factor of 2.5 (from 0.2 to 0.5) and depends on the synthesis conditions and type of hydrocarbon. The ratio of the refractive index at a wavelength of 1064 nm to its value at 532 nm with an increase in the average particle size increases slightly or remains approximately constant (in the range of 0.8 to 1.15) for most soot particles or increases more significantly (from 1.1 to 1.5) in the case of acetylene soot. The observed significant changes in the optical properties are correlated to a decrease in the average distance between parallel graphene planes in the structure of growing soot particles and an increase in the number of adjacent parallel planes. These structural changes characterize the graphitization process of soot particles as they grow.

Based on two- and three-dimensional numerical simulations, a new physical phenomenon is predicted during the decay of an elongated plasma region with hot electrons formed as a result of target ablation in vacuum by a femtosecond laser pulse focused on its surface by a cylindrical lens into a stripe with a width of several to hundreds of microns. It is established that both in the absence and in the presence of external magnetic field (up to ~103 T), oriented along the target surface in the direction of the axis of the semicylinder with electrons heated to keV energies, the multiple formation of thin filaments of the electron current and their further expansion together with the cold plasma cloud’s expansion can occur. It is shown that an inhomogeneous system of such filaments with the transverse dimensions ranging from a few to tens of microns develops due to the Weibel-type instability resulting from the anisotropic cooling of an expanding electron cloud and exists at times ranging from picoseconds to nanoseconds, creating localized magnetic fields ranging in strength from a few to several hundreds of T.

This paper presents a mathematical formulation of the problem of artificial freezing of a soil containing mineralized pore water (brines). The case of soil freezing with the help of a single freezing column is considered. It has been established that the migration of dissolved salt in brine occurs only through molecular diffusion. A numerical algorithm is proposed that allows to calculate the distribution of temperature and concentrations of the studied components and phases: brine, ice, salt dissolved in liquid brine, and salt precipitated into a solid insoluble precipitate. A numerical solution of the problem is obtained and some features of the temperature and concentration fields of the studied components and phases are studied.

A numerical study of turbulent (Re = 40 000) flow around a solitary conical dimple with a depth of 0.233 of the spot diameter on the wall of a narrow channel (with a cross section of 2.5 × 0.33) is carried out with change in slope angle θ. The transformation of the jet-vortex structure of the mean flow from a symmetric system of paired vortices to a monotornado flow leads to an intensification of the separated flow and heat transfer enhancement. The maximum velocities of the return and secondary flows increase by 25 and 40%, respectively, while the maximum turbulent energy drops abruptly by 30%. The minimum relative negative friction at the bottom of the dimple decreases by a factor of 2.5 (reaching –1.5). After θ = 45°, there is a fairly rapid decrease in the intensity of the separated flow in the dimple. The thermal efficiency of the control section with a dimple noticeably lags behind the growth of relative hydraulic losses; however, thermal-hydraulic efficiency THE = (Numm/Nummpl)/(ξ/ξpl)1/3 is close to unity.

In this work, samples of metallic aluminum are objects of sub- and supercritical water oxidation. Experimental studies have been carried out, and dependences of the effect of temperature, pressure, reaction time, and pH of the oxidizing agent on the phase composition of the oxidation products and their adsorption properties have been revealed. Experimental studies have been carried out in the temperature range of 275–380°C, reaction time from 3 to 12 h, and different water pH of 7–12. Maximum specific surface S = 120.2 m2/g samples obtained at temperature T = 380°C and reaction time τ = 3 h with pH 12. The phase composition of this sample included aluminum oxide γ-Al2O3 (92.3 wt %) and corundum α-Al2O3 (7.7 wt %).

The temporal dynamics of the change in the thermally-induced induced reflection coefficient of polycrystalline gold, aluminum, and molybdenum at a wavelength of 800 nm as a result of exposure to a femtosecond laser pulse (at a wavelength of 400 nm) with an intensity of up to 0.2 TW in the in the picosecond time range is studied using pump-probe optical scheme with phase-sensitive detection. New experimental data are obtained on the change in the reflection coefficient under strongly nonequilibrium conditions when the electron subsystem is heated to temperatures of ~10 kK, which are relevant for the development of the experimental base for numerical simulation.

An experimental setup and a technique for measuring the thermal conductivity of permanent-magnet samples with different orientations of magnetic-field lines in space are described. The anisotropy of the thermal conductivity of the magnet is revealed. The obtained measurement results are presented in the form of graphs and generalized by regression equations. The mechanism of heat conduction is refined, and the reason for the anisotropy of the thermal conductivity of a homogeneous body under the influence of a magnetic field is established. An explanation of the causes of the appearance of dark and light spots on the surface of the Sun is given.

The possibility is shown of measuring the temperature field, the droplets sizes, and the irrigation pattern of an impact surface during spray cooling with the use of high-speed IR thermography, video visualization, and a transparent design of the heating element. New experimental data on the heat transfer intensity are obtained. In particular, it is shown that the heat transfer coefficients during spray cooling are 1.5 times higher than the maximal heat transfer under multijet cooling regime. The liquid flow rate for the spray nozzle is lower by almost 5 times compared to the multijet nozzle.

In this paper, we study the shock compressibility and spall strength of composites reinforced with carbon fibers and glass fibers using a VISAR laser interferometer. A two-wave configuration is shown to form in both composites during the propagation of a shock wave along the fibers. The two-wave configuration in fiberglass is observed up to a shock-compression pressure of 18 GPa while in a carbon-fiber reinforced polymer (CFRP), it is recorded in the entire studied range of pressures up to 33 GPa. The Hugoniots and spall strength of composites were determined at various fiber orientations.