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The physical processes of crystallization of melt droplets in water have been studied using the droplet granulation and melt centrifugation methods. A mathematical model has been developed that makes it possible to determine the cooling and crystallization rates and dendritic structural parameter of aluminum alloy granules from the initial data of the process, the diameter of melt droplets, and cooling conditions. Predicting the dendritic parameter of the microstructure of granules allows one to predict the level of microstructure dispersion and hence the strength properties of the granulate material. The model parameters take into account the speed of droplet motion, features of heat removal processes, and the temperature dependence of the thermophysical parameters of the media. An application program implementing the developed mathematical model has been developed. Implementation of the developed mathematical model has been carried out using the Microsoft Visual C++ programming language. The mathematical model has been tested in the granulation of highly alloyed aluminum alloys (D1 and D16 alloys of the Al-Cu-Mg system, and B95 and B96Ts alloys of the Al-Zn-Mg-Cu system) obtained by centrifugal melt spraying and the droplet methods with cooling in water. Crystallization rate in full-scale samples has been measured based on an analysis of the dendritic structural parameter of the material. Analysis of the calculated values of the dendritic parameter and its measurements for real granule samples has shown that there is good agreement between the simulation and measurement results.

The deposition of a nickel-based cermet coating containing 60 % tungsten carbide has been studied. The effect of substrate preheating up to 500 °С on the intensity of the in-situ synthesis of secondary ceramic particles obtained by dissolving the initial particles in a metallic matrix has been investigated. It has been shown that preheating contributes to the prevention of cracks and pores in the coating. Using synchrotron radiation, it has been found that additional heating of the sample during surfacing to a temperature of 500 °С does not cause significant changes in the phase composition of the resulting composite.

The influence of substrate preheating on the structure of a cermet-coating obtained by direct metal deposition from Ti64 alloy reinforced with B₄C particles. Coatings containing 15 %. B₄C were obtained for the first time. It has been shown that the use of substrate preheating makes it possible to produce cermet coatings without cracks. It has been found that in tribological tests, that the scratch volume of the cermet coating decreases by a factor of eight compared to the coating with the content of B₄C 10 %.

Results on a nanoparticle collision with a target calculated by the molecular dynamics method are presented. The first problem being solved is a nanoparticle collision with a target under the conditions of cold gas-dynamic spraying. The second problem deals with nanoparticle extension, which adheres to the target due to the collision. It is shown that a chemical bond between the nanoparticle and target due to the collision. The bond in the case of titanium nanoparticle impingement onto an aluminum target is found to be stronger than that in the case of aluminum nanoparticle impingement onto a titanium target. The reason is that the titanium nanoparticle penetrates into the aluminum target to a greater depth.

The centrally symmetric problem of determining the velocity field in a continuous elastoplastic medium under a camouflage explosion has been solved using the assumptions of the unoscillatory nature of the motion and the incompressibility of the medium in the regions of plasticity and elasticity. The solution was found using a camouflage equation-the relation for determining the pressure on the contact surface of an expanding explosion cavity. The solution allows one to estimate the dimensions of the expansion and plastic deformation regions and the impact of explosive disturbances on objects

A nitrogen jet expanding during its exhaustion from a nozzle into a vacuum chamber is numerically simulated by a hybrid approach. The flow parameters in the nozzle and in the near field of the jet are determined by solving the Navier-Stokes equations by using the ANSYS Fluent software. The gas flow at large distances from the nozzle exit is modeled by the Direct Simulation Monte Carlo method by using the SMILE software system. Such an approach makes it possible to perform sufficiently accurate simulations in the near field of the jet; moreover, the temperature nonequilibrium of the expanding gas jet and other effects of rarefaction in the far field of the jet are taken into account. The approach is verified by using various approximate analytical models of gas exhaustion into vacuum. A comparison of the numerical results with available experimental data shows that they are in good agreement.

The flow in a far plane momentumless turbulent wake is described using a mathematical model obtained from the algebraic Rodi model of Reynolds stresses. The model is similar to the two-parameter ( k ̶ ε ) turbulence model in the far-wake approximation with a modified empirical constant in the diffusion terms of the equations. A group-theoretical analysis of the mathematical model of the wake was carried out and and a self-similar reduction of the equations of models to a system of ordinary differential equations was performed. An approximate solution of the corresponding boundary value problem is constructed using an asymptotic expansion of the solution in the neighborhood of the singular point.

A passive method for reducing the drag of cylinder by installing a flat plate behind it at a Reynolds number Re=10⁵ has been studied. The paper presents the results of an ANSYS Fluent simulation of the flow around the cylinder-plate system, including the velocity and pressure fields, streamlines, and the dependences of the drag coefficient and the position of the separation point on the surface of the cylinder on the relative length of the plate. It has been found that the drag coefficient of the cylinder-plate system can be reduced by approximately 40% compared to the case of an isolated cylinder.

The full Navier-Stokes equations are used to study the linear stability of plane Poiseuille flow in a channel with the lower wall corrugated along the flow, due to which the flow has two velocity components. The generalized eigenvalue problem is solved numerically. Three types of disturbances are considered: flat periodic (the Floquet parameter is zero), flat doubly periodic (finite values of the Floquet parameter), and spatial. Neutral curves are analyzed in a wide range of the corrugation parameter and Reynolds number. It is found that the critical Reynolds number above which disturbances that increase over time appear depends in a complex way on the dimensionless amplitude and period of corrugation. It is shown that in the case of flow in a channel with corrugated wall, three-dimensional disturbances are usually more dangerous. The exception is the small amplitude of corrugation, at which plane disturbances are more dangerous.

This paper presents the results of a statistical analysis of the turbulent structure in a free bubbly jet at a Reynolds number of 12500 based on PIV measurements of the carrier-phase velocity. The distributions of higher-order statistical moments for velocity fluctuations (skewness and excess coefficients) and the energy spectra of turbulence for single-phase and gas-saturated jets were obtained after applying the procedure of statistical filtering to instantaneous velocity fields. The influence of the dispersed phase (bubbles with an average diameter of 0.8 mm) with a volume gas fraction of 0, 1, 2, and 3% for the specified characteristics of the continuous phase was analyzed.