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High-resolution spectra corresponding to the rotational and the ν₂-ν₂ bands of the two most abundant isotopic species of ozone with one heavy ¹⁸O oxygen atom were recorded using SOLEIL synchrotron radiation source in the range 30-200 cm^-1. Additionally, the ν₂ vibrational-rotational bands were recorded between 550 and 880 cm^-1 using a classical glowbar source that made it possible to extend and refine information compared to published data on the observed transitions of these bands. The analyses of recorded spectra permitted us to deduce experimental set of energy levels for the ground (000) and the first bending (010) vibrational states, which significantly exceeds literature data in terms of rotational quantum numbers. For both isotopic species, the weighted fits of all experimental line positions were carried out including previously published microwave data. As a result of this work, the improved values of rotational and centrifugal distortion parameters for the states (000) and (010) were obtained that permitted modelling the experimental line positions with a weighted standard deviation of 1.284 (2235 transitions) and 0.908 (4597 transitions), respectively, for ¹⁶O¹⁶O¹⁸O, and 1.168 (824 transitions) and 1.724 (2381 transitions) for ¹⁶O¹⁸O¹⁶O.

The paper presents the results of a numerical study of flow gas dynamics and integral parameters of the flow at the channel entrance located behind a conical or plane shock wave. The free-stream Mach number range is М = 2 - 4 and the range of the slopes of the compression surfaces of the wedge and cone is δ= 10 - 90°. Data on the flow structure at the channel entrance, mean-mass Mach numbers, total pressure loss, and flow rate coefficients are obtained. A comparative analysis of these parameters is performed, and advantages and drawbacks of the channel entrance positions in various types of the flow are noted.

Rarefied gas flow into a vacuum through short linearly diverging and converging channels has been examined with the direct simulation Monte Carlo method. Solution to the problem has been suggested using complete geometric setup, with quite large areas on inlet and outlet of a model channel in examined geometry. A mass flow rate through the channel and flow field both inside the channel and upstream and downstream have been calculated in a wide range of gas rarefaction. These calculation results are comparable to corresponding data for the channel with constant cross section. A strong impact of channel geometry and gas rarefaction has been proved.

The paper presents the results of experimental study for rising a cluster of monodisperse gas bubbles in viscous liquid with/without surfactant for the Reynolds number in the range Re = 0.01 ÷ 1. The influence of surfactant type on the dynamics the bubble cluster rise has been analyzed. The qualitative pattern of monodisperse bubbles cluster rise was defined as a function of initial volumetric concentration in the range С_V = 0,001 ÷ 0,04. New experimental data were obtained on velocity and drag coefficient for a compact cluster of monosize bubbles rising in a liquid with/without surfactant (both for contact and contactless type of bubble rising.

The paper studies the quality of water spraying by a pneumatic injection system designed for water injection into the input system of a piston internal ignition engine. The system consists of a two-cylinder piston compressor with compression of water-air mixture phase in the compressor’s cavities. The piston compressor has connection to the atomizer through long channels. The droplet sizes were measured through automatic image processing by the Shadow Photography method. The velocity field of droplets was measured by the 2D-PIV method . Experimental results demonstrated that the injection system offers a high quality of spraying for the air/water mass ratio higher than 0.46. The value of Sauter mean diameter was less than 31.1 µm.

The research considers the microwave treatment of snow-and-ice mass with the stages of heating and melting. A nonlinear mathematical model for two-phase Stephan problem was developed for the case of laminar set of dielectrics. We offer approximate analytical solutions for taking into account the thermophysical and electrophysical properties of layers; this approach allows parametric analysis.

The papers analysis the flow patterns for air flow around cubic-shaped buildings. Experimental and simulation data were compared for the flow problems with different scales. Geometry parameters for the models can be varied from 0.025 to 6 m, meanwhile the range of Reynolds number for considered data is from 10⁴ to 10⁶. The study proves that the problem is scalable one: this creates a foundation for running the lab-scale wind tunnel experiments.

Using an ultrasonic interferometer in the temperature range from 293 to 393 K at pressures from 0.13 to 1.5-2.8 MPa, the speed of sound U was measured in helium-xenon gas mixtures with a helium content of 60.34, 71.72, and 85.32 at. %. The measurement errors of temperature, pressure and speed of sound were ±20 mK, ±4 kPa and ± (0.15-0.30) %, respectively. By approximating the experimental data for each composition, equations were obtained to describe changes in the speed of sound as a function of pressure and temperature over the entire measurement range. The existing reference and experimental data on the speed of sound in inert gases and He-Xe mixtures were analyzed. A method for calculating U of mixtures with a helium content above 71.7 at. % He to a temperature of 1500 K and a pressure of up to 7 MPa was developed.

Numerical simulation was applied to the processes of heat and moisture transfer and for ice-water phase transition in a season-thawed soil layer. Analysis was performed for consequences of natural wildfire on the soil temperature and the thawing depth as a function of water retention by soil for the condition of Siberian permafrost zone. Calculations demonstrate that the permafrost thawing depth increases due to burnout of the top organic horizon. The quantitative indexes of natural wildfire impact depend on water retention properties of the upper organic horizon of soil.

Using isothermal drop calorimeter, the enthalpy increment of the Na₁₅Pb₄ and Na₅₀Pb₅₀ alloys was measured and the heat capacity was determined in the temperature range of 420-1075 K, including the solid and liquid states. It has been established that the values of the heat capacity of melts significantly exceed the calculations of this value according to the laws for an ideal solution, and this difference decreases with increasing temperature. The obtained results confirm the currently known fact that various complexes with a partially ionic character of the interatomic interaction are formed in melts of alkali metals with lead systems.