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Results of studying interaction of two colliding axisymmetric laminar microjets of hydrogen in the course of their diffusion combustion are reported. Gas exhaustion occurs with identical velocities through pairs of micronozzles, which are thin-walled cylindrical tubes with an inner diameter of 200   m. The transverse positions of the tubes with respect to each other are changed during the experiment. Specific features of flame formation from two interacting microjets are found for different transverse positions of the tubes, and the results are compared with flames of single microjets with the same exhaustion velocity.

This study is aimed at understanding some characteristics of the shock wave generated by a novel composite charge consisting of an inner high explosive, a medium non-detonating layer, and an outer aluminized explosive. The influence of the shell restraints and initiation modes on the peak overpressure and impulse of the charge is investigated. Numerical models are developed based on the mapping function of AUTODYN for determining the spatial distribution of the shock wave overpressure. By means of validation experiments, the accuracy of the developed model is verified. It is found that the peak overpressure and impulse obtained from experiments and simulations are in good agreement, with a deviation of less than 16.9%. The difference in the overpressures at various azimuths decreases with increasing distance, and the shock wave profile eventually evolves into a spherical shape. The radial overpressure of the shelled composite charge is initially greater than that in the axial direction and decays rapidly with increasing distance. The azimuth corresponding to the maximum peak overpressure is shifted from 75oC for the bare charge to 110 °C for the shelled charge. It is found that the energy utilization of the composite charge under inner initiation is apparently smaller than that under simultaneous initiation.

The countercurrent flow of a falling liquid film and a turbulent gas flow in a narrow vertical channel is considered. In the case of small Reynolds numbers and when certain conditions are met for the parameters of such a flow, the problem reduces to the study of one evolutionary integrodifferential equation for the deviation of the film thickness from the unperturbed level. A numerical study of the evolution of periodic disturbances has been carried out. Several solutions to the model equation are presented

A mathematical model is proposed that describes the formation of internal hydraulic jumps and the mixing of co-directed flows of an ideal stratified fluid in the Boussinesq approximation. The model is based on a three-layer representation of the flow taking into account the entrainment of fluid from the outer layers into the intermediate vortex layer and is represented as a system of heterogeneous conservation laws. The speed of entrainment is given by the equilibrium condition within the framework of a more general model of evolution of the mixing layer. The speed of propagation of disturbances and the concepts of subcritical and supercritical flows are formulated. It is shown that the model is suitable for describing the mixing and splitting of flow in deep-sea currents. Solutions corresponding to the flow around an obstacle with the formation of an internal hydraulic jump and a region of intense mixing were constructed. The results of numerical modeling were shown to be in good agreement with experimental data.

Results of studying gas flows in a setup used for cold gas-dynamic spraying are reported. The setup consists of a cylindrical inlet channel with a central rod connected at a right angle with a rectangular slotted channel. Injection of a high-pressure gas through the inlet channel leads to gas acceleration. It is shown that there are velocity and pressure disturbances in a supersonic overexpanded jet exhausting from the channel, which arise due to the presence of compression and expansion waves, as well as streamwise vortices. The contribution of streamwise vortices to pressure and velocity disturbances is approximately 30%. Streamwise vortices are formed at the entrance of the slotted channel owing to curvature of streamlines.

Zeolites of the structural type ZSM-5 were synthesized using a template, which was pentaerythritol (PER), carbamide (CA), or a deep eutectic solvent (DES) - a binary mixture of PER and CA. It is determined by IR spectroscopy and X-ray diffraction analysis that the nature of the templates used in the synthesis of zeolites affects the phase purity and the degree of crystallinity of the obtained samples. The textural and acidic properties of zeolites and Mo-containing catalysts prepared from them by dry mechanical mixing with nanoscale molybdenum powder have been studied. It is shown that the textural properties of zeolites depend on the template nature. The use of CA promoted obtaining the zeolite with maximal specific surface area and pore volume. The strength of the acid centres of unmodified samples, depending on the structure-forming additive, decreases in the series: DES > CA > PER, and the concentration of acid centers of both types, on the contrary, decreases for zeolites in the series: PER > CA > DES. The catalytic activity of synthesized zeolites has been studied in the processes of non-oxidative methane conversion and refining of the straight-run gasoline fraction of oil. The dependence of the activity and stability of samples on their physicochemical properties caused by the template nature is determined. It has been shown that zeolite synthesized using DES and the 4.0%Mo/ZSM-5 catalyst obtained on its basis exhibit higher activity and stability in the processes of non-oxidative methane conversion into aromatic hydrocarbons and in upgrading the straight-run gasoline fraction of oil, in comparison with zeolite-based catalysts obtained using PER or CA.

The methods for producing cryogels and hydrogels from viscous aqueous solutions of polyvinyl alcohol (PVA) and their rheological properties are considered. Freezing an aqueous solution of polyvinyl alcohol, its exposure to negative temperature and subsequent thawing at a positive temperature lead to the formation of elastic cryogels. Chemical cross-linking of individual PVA molecules into spatial networks is accompanied by the transformation of aqueous solutions into hydrogels. Sodium tetraborate and glyoxal were used to structurise the polymer solutions. It has been determined that the interaction of these reagents with the functional groups of the polymer causes an increase in the viscosity of three-component systems “PVA - glyoxal - water” and “PVA - sodium tetraborate - water” with time. The kinetics of gel formation in the products of chemical reactions was investigated at different concentrations. It is shown that the viscosity of the studied systems increases with an increase in the concentrations of low-molecular reagents in both cases (PVA - glyoxal and PVA - sodium tetraborate). Hydrogels formed at a positive temperature were subjected to additional freezing-thawing cycle, cryogels were obtained, and their rheological properties were studied. The elastic properties of cryogels were determined to be more clearly pronounced than those of hydrogels. Hydrogels can be used as instantaneous gel-forming systems to protect from dangerous chemicals and to make waterproof barriers in hydraulic structures, as the elastic properties are enhanced after cryogenic exposure.

Using information from the database of the Institute of Petroleum Chemistry SB RAS and the methods of statistical and spatial analysis of geographical information systems, we evaluated the data on oil occurrence conditions in the Bazhenov, Domanik and Kuonamka Formations of the oil and gas bearing territories of Russia, the development of which will allow discovering the new sources of increased oil production. The digital maps of the arrangement of hydrocarbon fields in the Bazhenov, Domanik and Kuonamka sediments over the territories of the Volga-Ural, Timan-Pechora and Lena-Tunguska oil and gas bearing basins are presented. The distribution of oils from these deposits over the depth of occurrence in each basin is shown. The lithological features of reservoir rocks are established. The average values of reservoir parameters characterising the filtration and capacitance properties of the pools in these sediments are determined. To analyse the conditions of Bazhenov oil occurrence, a batch of 2833 oil samples from 127 fields of the West Siberian basin was used, for Domanik oil - 407 samples from 195 fields of the Volga-Ural and Timan-Pechora basins, and for Kuonamka oil - 117 samples from 28 fields of the Lena-Tunguska basin. A comparative analysis of the geological and physical characteristics producing a direct impact on the development regime and the effectiveness of technologies used to extract these hard-to-recover oils was carried out: permeability and porosity of rocks, reservoir temperature and pressure. It is shown that the Domanik and Kuonamka sediments are the closest in characteristics to the reservoirs of the developed American shale oil fields, which indicates the possibility for effective application of the positive experience of the United States for Russian oilfields. The results of the study can be used in the development of new and improvement of existing methods and technologies for the extraction and processing of hard-to-recover oils from the studied sediments.

Biogeochemical transformations of sulphur in the saline lakes of southeastern Transbaikalia have been studied. Quantitative measurements show that hydrogen sulphide is present in the water and bottom sediments of most of the lakes studied. In addition to hydrogen sulphide, the presence of sulphate, thiosulphate, and elemental sulphur was detected in the water column, while sulphate and elemental sulphur were found in the bottom sediments. It was established that elemental sulphur exists in the lakes primarily in the form of suspension and colloids, as well as polysulphidic sulphur, the amount of which increases with increasing water pH. It is concluded from the isotopic ratios of sulphur for sulphate, hydrosulphide ions, and elemental sulphur that sulphur in the studied natural systems is controlled by biological and geochemical processes. One of the processes controlling the behaviour of sulphate ions in the lakes is sulphate reduction, which leads to the enrichment of sulphate sulphur and depletion of sulphur in hydrogen sulphide with the ³⁴S isotope. It is shown that oxidation of reduced sulphur in the lakes proceeds with the participation of oxygen, iron, manganese, as well as various bacteria. The presence of an additional source of sulphur and/or absence of sulphur reduction causes ³²S accumulation in sulphate ions. It is determined that the loss of sulphate ions due to their bacterial reduction in bottom sediments is most pronounced in the chloride and soda lakes of the I and III subtypes. In the sulphate and soda lakes of the II subtype, an increase in the amount of sulphate ions was detected.

The discharge of untreated or insufficiently treated sewage into water bodies leads to their pollution, contributing to the emergence and spread of viruses and bacteria that have a negative impact on the ecosystem. One of the indicators of water contamination by pathogenic microorganisms is ammonium ions. The sorption method based on industrial waste as sorbent precursors has become widespread for treating wastewater from ammonium ions. The article presents the results of studies of a calcined sorbent based on ash-and-slag wastes from thermal power engineering plants for the treatment of real wastewater, discharged into the Kuban river within the city of Krasnodar, to remove ammonium ions (NH₄⁺ concentration 21 mg/dm³). The effect of sorption time (10, 30, 60, 90, 150, and 180 min) and sorbent dose (0.5, 1, 2, 3, and 5 g) on treatment efficiency is investigated. The experimental data are processed on the basis of kinetic equations. It is shown that the equation of the pseudo-first-order (Lagergren) provides the best description of experimental data on sorption in comparison with the pseudo-second-order equation (Ho and McKay) and the Elovich equation. It has been established that internal diffusion adsorption is the limiting stage. Treatment efficiency was 72.8 % at a sorbent dose of 5 g for solution volume 50 cm³ and sorption time 180 min. It is shown that the sorbent dose affects the time within which the phase equilibrium between the solution and calcined sorbent is established. The larger is sorbent dose, the larger number of adsorption centres are occupied by ammonium ions per unit time, so, for the fixed ammonium ion concentration in initial solution, shorter sorption time will be necessary to achieve equilibrium. For real wastewater, the time necessary for equilibrium to be achieved exceeds the value determined experimentally with the model mixtures using small sorbent doses. Reasonability of the application of calcined sorbent for treatment of real wastewater is confirmed.