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The dynamics of surface temperature changes for a water droplet resting on a structured black silicon substrate heated to 90°C were studied. The wetting properties of black silicon were analyzed during substrate heating in the temperature range of 30-90°C. Thermal imaging studies revealed that vapor nucleation sites form at temperatures close to the boiling point at the liquid-black silicon interface. The dynamics of temperature changes on the surface of a thin liquid droplet during the final stages of evaporation were studied, including the formation and subsequent development of bubble nuclei within the droplet. Convection and bubble formation were shown to result in non-uniform temperature fields.

This study is aimed at improving environmental efficiency by establishing the dependence of the parameters of optimal combustion of liquid hydrocarbon fuels (diesel fuel, crude oil, fuel oil, kerosene, waste oil) on their physical properties using steam atomization with superheated steam. The methodology includes the construction of regime maps of CO concentration with approximation by radial basis functions and smoothing by a median filter. During the study, a statistically significant linear relationship between the angular coefficients of the optimal regime equations and the Laplace number (r = 0.834, R2 = 0.7) was established. Based on the obtained dependences, an equation is proposed to calculate the optimal flow rate of superheated steam depending on the Laplace number for the optimal combustion mode of liquid hydrocarbon fuels in an atmospheric burner with steam atomization and a gasification chamber to reduce emissions of harmful substances.

An installation was designed, fabricated and studied for methane pyrolysis and hydrogen production. Methane heating and pyrolysis occurs by burning a fraction of methane-hydrogen mixture (60 % hydrogen and 40 % methane) produces by pyrolysis (a return for the plant demand). The installation thermal design was performed with the account for the heat consumed fro pyrolysis, insulation heat loss and flue gases loss. The study determined the plant heat power and the efficiency coefficient. Usage of methane-hydrogen mixture as fuel allows reducing the CO₂ emission as compared to known methods of hydrogen production.

Using the integral heat balance method, analytical solutions were obtained for the formation of dynamic and thermal boundary layers in a methane pyrolysis (thermal decomposition) reactor with variable viscosity and thermal diffusivity within these layers. It is shown that, on the inner surface of a metal reactor wall heated to 1000°C, a layer of stagnant gas forms due to high viscosity and thermal diffusivity, having the same temperature as the wall. Isotachs and isotherms in this layer are located perpendicular to the wall surface. In this case, boundary layers form at a certain distance from the wall, within which the velocity is practically zero and the temperature is equal to the wall temperature, significantly exceeding the gas temperature outside the boundary layers. In the near-wall layer of stagnant gas at high temperatures, intensive carbon formation (pyrolysis graphite) occurs, depositing on the reactor walls until the reactor flow cross-section is completely carbonized and the pyrolysis process stops.

To create an efficient microchannel reactor for hydrogen production, steam reforming of carbon monoxide in a slotted annular channel was experimentally studied. The microchannel reactor is formed by a submillimeter gap between two cylinders, with a catalyst applied to the outer side of the inner cylinder. Platinum applied on cerium oxide was used as a catalyst. The thermal characteristics of the shift reaction with the formation of carbon dioxide and hydrogen were experimentally studied. Experiments were carried out at a steam-to-carbon monoxide ratio of 3:1 at different mixture flow rates. It was shown that a fourfold increase in the mixture flow rate leads to a significant increase in the temperature difference between the reactor inlet and outlet, caused by the heat release of the reaction (from ΔT ≈ 20°C at a contact time of 189 ms to 80°C at a contact time of 46 ms). According to analysis of the composition of the outgoing gas, with an increase in the mixture flow rate, the degree of carbon monoxide conversion decreases significantly.

The paper presents the direct numerical simulation for a laminar flame of a premixed methane-air mixture using a detailed kinetic mechanism. During this study, the numerical module laminarSMOKE is supplemented by a problem of conjugated heat transfer between the flame and nozzle walls. A change in the isothermal boundary condition on the nozzle wall influencing the conjugated heat transfer condition results in a higher temperature of the temperature of the nozzle front edge, reduction in the flow density gradient near the nozzle boundary and a reduction in the low-frequency oscillation of flame caused by the buoyancy effect.

A study on transition processes for experimental time dependencies of the pitch angle for the case of free rotation of a body discovered the final intervals with a steady amplitude of oscillations - known as quasi self-oscillations. Statistical analysis demonstrated that the maximum possible difference between the amplitudes of self-excited oscillations (including the case of quasi self-excited oscillations) at the normalized oscillation frequency of 0.02 was about 1 degree.

The supercavitation cavities were studied in a slot channel with a wing-shaped body inside. The wing attack angle was 21°. The dynamics of tracing flat cavitation bubbles were studied using a high-speed camera. The methods of algorithmic diagnostics of two-phase flow were used to detect the size of bubbles, their velocity, direction of movement and spatial distribution. It is shown that there are three types of supercavitation cavities arising in slot channels: a transparent pulsating cavitation cavity with periodic vortex formation at the site of its closure; steam and a steam-water mixture coexisting inside the cavity; a cavity completely filled with liquid with tracing steam-gas bubbles inside. It is determined that the bubbles move into the supercavitation cavity from its boundaries to the center; further they move to the front of the cavity and merge with it. The maximum velocity of bubbles is half the velocity of the oncoming flow.

The emergence and development of a vortex system during the separation of a supersonic air flow on the rib of a dihedral model with face opening angle of 270° was studied in details. The appearance of a separation vortex above the lateral face was detected for a flow with an angle of attack α = 1º. For a case with α ∽ 2º, boundary layer separation occurs near the rib of angle-shaped configuration. With an increase in pressure drop between the top and lateral faces of the model, the separation flow size grows and at an angle α = 3.7º a new vortex form is observed (a secondary vortex). For a flow with an angle of attack α = 8º, a third vortex is clearly observed. This vortex is located above the secondary vortex and it has a minor influence on the pressure distribution and the limiting streamlines behavior on the lateral face. The flow at this angle of attack α results in repeated separations for thin boundary layers near the configuration rib and beneath the enlarged secondary vortex. Within the tested interval of the attack angle α = 8º - 24º , the sizes of those local separations remain almost the same. It was shown that analysis of limiting streamlines patterns and surface pressure distribution cannot fully elucidate the actual structure of complex vertical systems without gaining some additional data.

Theoretical models of aerothermochemical interaction between a flow surface and dissociated air are presented for the case of combustion and sublimation near the forward stagnation point of a blunt body. Research methods and results are generalized to obtain a solution based on the similarity method for the case of combustion and sublimation using graphite in arbitrary cross-sections of a cone, sphere, wedge, cylinder, plate, and spherically blunt cone under laminar flow conditions with high Reynolds numbers. For various geometric shapes in a wide range of hypersonic flow conditions, calculations of the mass flux, heat flux, and friction drag coefficient are presented, the results of which are linked by universal dependencies expressed in terms of the stagnation enthalpy, pressure, velocity gradient, pressure gradient parameter, and surface temperature.