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Based on a system of gas dynamics equations for a mixture of vibrationally excited chemically reacting molecular gases, the effect of a carbon dioxide additive on the stability of a hypersonic boundary layer of neutral nitrogen on a plate was studied. Calculations were performed for five mixture composition variants. Steady-state flow parameters were calculated using a locally self-similar approximation of the boundary layer equations. Within the framework of linear stability theory, the dependences of the critical Reynolds numbers Re_δc and the laminar-turbulent transition Reynolds numbers Re_xT* on the molar concentration of the additive were obtained. In particular, for a 50% mixture, the relative increase in both criteria compared to the corresponding values for a mixture of perfect gases is approximately 53%. Moreover, the contribution of CO₂ dissociation to the shift of the laminar-turbulent transition zone is twice as great as the contribution of vibrational mode relaxation. It is shown that the obtained dependence ofRe_xT* on the molar concentration of the additive correlates with the corresponding experimental results of Professor H. Hornung's group.

This paper considers a relation between the emissivity of metals from the V period of the Periodic System while melting process with thermophysical properties: surface tension coefficient (γ) and specific heat capacity (C_p). Taking the own and available experimental data and using the theoretical calculation within Foot’s approximation, we elucidated the laws of emissivity as a function of electronic stricture and interatomic interaction. It was demonstrated that a correlation between the emissivity and γ and C_p has a complicated behavior and this is dictated by general trends (emissivity increases with γ) and by a specific electron configuration for given elements. The results underline the importance of considering the periodicity and electronic configuration in forecasting the thermophysical properties of metals in the phase transition state.

The results of an experimental study of the influence of tabs (teeth) of various shapes on the intensity of turbulent heat transfer in the separation zone in the near wake of a backward-facing step are presented. In this stagnation region, a significant decrease in heat transfer is observed, which negatively affects the thermal-hydraulic efficiency. Five tab shapes were studied in the experiments: square, triangular, cylindrical, semi-cylindrical, and semi-conical ones. The tabs were installed at the step edge immediately before flow separation. Measurements were conducted at Reynolds number Re_Н = 4000 and varying tab pitch. It was found that square tabs with a pitch of 2.5 calibers (step height) have the greatest effect on flow and heat transfer, but at the same time, they cause the greatest hydraulic resistance, therefore, their thermal-hydraulic efficiency is lowest. Semi-conical tabs installed with a pitch of five calibers showed the best results.

The dynamics of dispersed phase propagation during injection of a gas-droplet wall jet into a co-current turbulent heated airflow is numerically simulated with variations in the droplet mass concentration at the inlet cross-section and their initial diameter. The solution is based on a system of axisymmetric Reynolds-averaged Navier-Stokes (RANS) equations, taking into account the two-phase character of the flow. The Eulerian approach is primarily used to describe the aerodynamics and heat and mass transfer in the gas and dispersed phases. The Lagrangian and full Lagrangian approaches are used in the study for additional verification of the developed mathematical model. A significant effect of the liquid mass concentration on the particle concentration profiles across the channel cross-section is demonstrated. The results obtained using the Eulerian and Lagrangian descriptions are compared. The applicability of both approaches for describing the dynamics and heat transfer of a two-phase wall jet is demonstrated (the difference between the two approaches does not exceed 15%).

A numerical study of the flow in a tangential vortex chamber using unsteady full and Reynolds-averaged Navier-Stokes equations is presented. The spatial flow of a viscous incompressible gas (air) is considered at Reynolds number Re = 3.4·10⁴. The distributions of the axial and circumferential velocity components, as well as their pulsations, are analyzed. It is established that the solution of the full Navier-Stokes equations provides distribution of parameters in a swirling flow close to the results of experimental measurements, whereas turbulence models based on the Boussinesq hypothesis do not allow numerically reproduction of the dynamics of a confined swirling flow.

Ground-based simulation of processes around space vehicles in open space is a topical issue for rocket industry. Some problems can be covered by middle-size vacuum-based gas-dynamic setups; they provide model flow regimes for imitation of natural regimes befitting from low financial and material costs. The updates for the laboratory vacuum setup LAMPUS-2 based in Novosibirsk State University and improvements in gas dynamic diagnostic tools enabled a wide range of study for supersonic jets emerging from a nozzle cluster. This paper presents the measurement results performed for binary cluster jets using photo visualization method and scanning of argon flows for different ratio of stagnation pressure to the ambient pressure. The process of condensation has a significant influence on the dynamics of interacting jets.

The three-dimensional structure of the flow in narrow gaps between fuel assembly (FA) rods has a decisive influence on the heat and mass transfer coefficients, which, in turn, determine the FA performance. In this work, instantaneous three-dimensional velocity fields were measured for the first time in a model of a FA peripheral cell using the Tomographic PIV method with high temporal resolution. The experiments were performed at Reynolds number Re = 2100. The study, conducted using the TR-Tomo PIV method, allowed characterization of the three-dimensional structure and dynamics of the flow in a narrow gap of a FA peripheral cell. Based on the obtained data, the components of the vorticity vector in the flow volume were calculated. It is shown that the key mechanisms, responsible for generation of extreme values of longitudinal vorticity, are transverse flow oscillations. These oscillations are quasi-periodic in nature (Sh = 0.091) and alternate with stabilization phases, which are characterized by a straight-through flow.

A newly discovered phenomenon-the sudden dispersion of starch grains upon a sharp decrease in ambient pressure-was experimentally studied. The aim of the study was to determine the mechanism of this phenomenon. This effect was observed for various types of starch: potato, corn, and rice. It was established that starch moisture content is the primary parameter determining the occurrence of this phenomenon. The experimental results showed that grain dispersion occurs due to the reactive force generated by evaporation and release of water from the starch grains. The release is caused by an increase in water vapor pressure within the starch grains due to a phase transition of water upon a decrease in external pressure. The data obtained may be useful for further research in materials science and biotechnology, as well as for the development of new methods for studying the properties of starch materials.

The development of optoelectronic methods for measuring through a multiphase barrier in the study of a dispersed component in experiments on modeling the natural and technical hydrodynamic systems is a pressing issue. The difficulties of direct measurements under hurricane conditions necessitate laboratory measurements. Spray formation was studied in detail during the laboratory experiments in the high-speed wind-wave channel (WWC) at the Institute of Applied Physics of the Russian Academy of Sciences (IAP RAS). A modern, non-contact optical method for diagnosing two-phase flows-laser Doppler anemometry (LDA)-was used to measure the kinematic characteristics of the aerosol flow. Experiments were carried out to measure the aerosol droplet aerodynamics in WWC of IAP RAS. It was demonstrated that the measuring system enables to measure all three components of the aerodynamic flow velocity through a multiphase barrier at wind speeds from 10 to 40 m/s over a wide range of conditions. The results of measurements were compared with the readings of the Pitot tube, and good agreement and reproducibility of the experimental results were shown.

A method to synthesis new hybrid derivatives of α-pinene with α-aminophosphonate fragment has been developed to obtain an additional centre of metal coordination in the molecules of potential extractants for heavy metals. It has been shown that O-alkyl ethers of α-amino oximes of the pinane series can be converted according to the two-stage version of Kabachnik-Fields reaction with dimethylphosphite and benzaldehyde into new chiral α-aminophosphonates with a satisfactory preparative yield (40-42 %). According to this scheme, terpene aminophosphonates are obtained as highly lipophilic products in the form of a pair of stereoisomers with a diastereomeric purity of 49-66 %.