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The possibility of controlling the structural-phase composition of a VT6–
B₄C titanium matrix composite during direct laser deposition was investigated. A
correlation was established between the laser processing parameters and the
resulting microstructure: changes in energy input led to changes in the
concentration of secondary phases (TiB, TiB₂, TiC). Synchrotron radiation
diffraction was employed to obtain high-resolution diffraction patterns, which were
used to determine the qualitative phase composition of the fabricated titanium
matrix composites. It was demonstrated that using a high-energy set of processing
parameters results in a significant increase in microhardness, reaching up to 750
HV_0.3.

In this paper, the modified polyaryletherketone (PAEK) was used as a toughening agent to prepare the PAEK/epoxy blends. Effect of PAEK on the erosive wear behaviors of blends was also investigated by the water jet technology. The surface morphologies of the wear scars were examined. With the increased of the PAEK content, the hardness and the impact toughness showed the phenomenon of first increased and then decreased. The erosive wear resistance of the epoxy resin blends was improved significantly, especially when PAEK content increases up to 35 phr. The erosion wear rate of the specimen shows 9.1% reduction than that of unmodified epoxy resin sample. The material removal occurred on the eroded surfaces of the epoxy blends due to the micro-ploughing, cracks, micro-cutting and plastic distortion. All these results suggested that the addition of PAEK could optimize the structural strength, indicating that the PAEK/epoxy blends are suitable for erosive environments.

This study delves into the impact of low-velocity loading and thermal effects on Functionally Graded Material (FGM) circular plates crucial in aeronautical and space engineering. Examining varied conditions, the focus lies on radial displacement and transverse deformations in hot, ambient, and cold environments. Notably, findings highlight an increased likelihood of damage in hotter scenarios, emphasizing the imperative need to design FGM plates with enhanced resistance against impact loads and thermal stresses in extreme conditions. These results bear crucial implications for aerospace applications, guiding the development of FGM plates that can effectively withstand challenges in diverse environments.

This research investigates the influence of Nb₂O₅ coatings, produced by using reactive sputtering technique, on the surface of middle-tension specimens M(T), regarding fatigue crack growth curves (da/dN versus DK) under exposure to a 0.6 mol L^-1 NaCl saline solution. Results demonstrated the corrosion process occurred in the vicinity of the crack tip, where stresses are elevated, and significant plastic deformation prevails, notably influenced by slip bands that induce micro-cracks, exposing fresh material layers to the corrosive surroundings. The Nb₂O₅ coatings enhanced the fatigue-corrosion resistance of the 2198-T851 aluminium alloy. This study marks an initial step towards more comprehensive investigations into the impact of Nb₂O₅ coating on improving the mechanical properties of the 2198-T851 aluminium alloy.

The experimental data on mass transfer during ethanol evaporation and combustion in the boundary layer on a horizontal surface are analyzed. The effects of a barrier (up to 15 mm high), external turbulence (up to 26%) and air velocity (up to 58 m/s), close to the flameout velocity in the boundary layer, are considered. The review is supplemented with experimental data for narrowing and expanding channels. The conclusion that the limits of mass transfer intensity during combustion are determined by the regularities for laminar and turbulent boundary layers on a smooth impermeable plate during evaporation without combustion is confirmed.

The paper considers spherical gas bubbles in liquid with radial oscillations induced by acoustic field. The account of development and application of the homobaric model is presented. Several publications on this topic have been discussed.

This work deals with the study of cavitation in a slit channel when flowing around NACA 0012 hydrofoils with smooth and periodic roughness on the surface. The research was aimed at the description of the dynamics of cavitation cavity development on smooth and rough hydrofoils and determination of differences between them. Computer modeling of cavitation flow in a slit channel formed behind an obstacle in the form of a wing was performed in the modern CFD package STAR CCM+. Visualization was obtained, computer modeling was carried out in a wide range of parameters, and a comparison with experimental data on the cavitating flow was made. The effect of periodic roughness on the features of occurrence and development of a cavitation cavity on the hydrofoil is described. The flow structure in roughness cells is shown. The obtained results can be used to control effectively the cavitation process in slit sections of various hydraulic engineering devices.

The paper describes the response of a viscoelastic layer glued onto a solid base to a non-stationary convective pressure wave. A complete equation of motion of coating material particles in the case of two-dimensional deformations is derived and it takes into account the viscosity of the medium. A system of equations for calculating the longitudinal and transverse dynamic compliance, determined by the ratio of the displacement components to the applied pressure, is obtained. The derived equations allow the description of not only stationary oscillations of the coating, but also the process of their stabilization. It is noted that, in addition to viscosity and Poisson ratio, stationary and dynamic compliances depend only on two parameters: the ratio of the disturbance wave velocity to the propagation velocity of shear oscillations in the coating and the ratio of the wavelength to the coating thickness. An example of calculating stationary compliance for a typical case of a silicone rubber coating is given. Attention is drawn to the need to take into account the transition period of the forced oscillation stabilization, since the coating cannot swing instantly due to inertia and viscosity. Known attempts to calculate this process have been analyzed.

Using a numerical model that includes a system of averaged hydrodynamic equations in the Oberbeck-Boussinesq approximation, differential equations for the Reynolds stress transfer and dissipation rate, a numerical model of the evolution of a flat turbulent spot in a turbulent stratified medium (degenerate background turbulence) is constructed. The components of the mass flux vector and the variance of density fluctuations are found from algebraic presentations of the local equilibrium approximation. Numerical modeling of the evolution of the turbulent mixing zone and the internal waves generated by this zone in a turbulent linearly stratified medium is performed. The calculation results demonstrate a significant effect of background turbulence on the development of the turbulent spot and internal waves generated by the spot. A large-scale turbulent background leads to generation of internal waves of significantly lower amplitude.

The experimental results on the study of the flow structure and pressure distributions on the wall and along the axis of the Coanda ejector mixing chamber are presented. The experiments were carried out in the range of changes in the absolute value of the total pressure in the prechamber P_K = 1.2 - 3.5 atm, which corresponded to both sub- and supercritical jet outflow regimes. The width of the annular gap through which the ejector flow was blown into the mixing chamber took the values h = 0.15, 0.25 and 0.5 mm. An increase in the vacuum on the wall in the initial part of the nozzle was observed with an increase in the total pressure. It was found that the static pressure distributions along the nozzle axis are characterized by the presence of a vacuum region almost along the entire length of the cylindrical channel. At subcritical jet outflows, recirculation zones can form in the vicinity of the channel axis near its inlet. A fundamentally different character of the velocity distribution and pulsation intensity in the cross-section of the mixing chamber is noted, depending on the outflow regimes.