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The effect of the parameters of a pulsed-periodic side jet on combustion of a hydrocarbon fuel in an axisymmetric channel flow with the Mach number of 1.7 is studied numerically. The Reynolds-averaged Navier-Stokes equations closed with the k-ε turbulence model are solved. Fuel combustion is modeled with the use of one reaction. It is demonstrated that the temperature of the gas generator for the jet produced only a minor effect on the shock wave structure of the flow. The key role belongs to the pressure of side jet injection. A transonic flow structure is obtained.

The paper presents a numerical simulation of a stagnant (suspending) gas slug in the Taylor flow fitted to the experimental conditions. The simulation is based on the unsteady model of k - ω SST (shear stress transport) turbulence. Simulation covers analysis of gas-and-liquid flow parameters in the zones ahead the slug, after the slug and for the liquid film. The study demonstrates a compliance between the experiment results and simulation regarding the liquid film shear stress, the slug nose shape and the film thickness.

The effect of the parameters of a pulsed-periodic side jet on combustion of a hydrocarbon fuel in an axisymmetric channel flow with the Mach number of 1.7 is studied numerically. The Reynolds-averaged Navier-Stokes equations closed with the k-e turbulence model are solved. Fuel combustion is modeled with the use of one reaction. It is demonstrated that the temperature of the gas generator for the jet produced only a minor effect on the shock wave structure of the flow. The key role belongs to the pressure of side jet injection. A transonic flow structure is obtained.

This study seeks to improve the film cooling performance by embedding a film hole in a V-shaped trench. The angle scale that makes up the V has been changed, 25°, 75° and 115°. The three novel designs were compared to rectangular (transverse) trench and conventional cylindrical hole. The main parameters of film cooling, cooling effectiveness, and total pressure loss, were discussed at three blowing ratios, M=0.5, 1.0, and 2.0. Fifteen cases were simulated using Reynolds averaged Navier-Stokes equations closed by the RNG k-ε model. A good agreement is obtained between CFD results with experimental data of the baseline case. The results showed that the use of compact jet in the trenches, whether transverse or V-shaped, enhances the film cooling effectiveness. The use of V-shaped trench helps to reduce the size of the kidney vortices (CRV) and, thus, enhance the film cooling performance. The V2 shaped trench is the most prefer in improving the film cooling efficiency and reducing the total pressure loss.

The paper presents a developed 2D mathematical model for a regenerative heat exchanger designed for a ventilation system operating with a periodic change in airflow direction. This kind of ventilation system saves the heat energy required for heating of domestic premises during a winter season. Results for calculations by a two-dimensional model are compared with one-dimensional modeling and with available experimental data. The authors formulated a definition of energy efficiency in terms of reduction in heat losses. Our calculations demonstrate that the efficiency of a regenerative heat exchanger might exceed 90 %. The numerical simulation was applied for parametric study of this problem; we revealed the influence of the heat exchanger operational and design parameters on the energy efficiency. Numerical experiments found a group of parameters most significant for energy efficiency of ventilation system; recommendations on system optimization were formulated.

The influence of the size of water droplets, temperature, and velocity of a streamlining jet of dry air on the rate of evaporation is considered. Due to the systematic studies using a thermal imager, it is shown that the interface temperature changes spontaneously. It is assumed that the temperature nonuniformity on the surface is caused by the release of vapor nanobubbles and can be characterized by the velocity of their outflow. Empirical regularities on the intensity of bubble release from a droplet are obtained both as a function of time and diameter, and in the criterion form.

The gasification of solid urotropine was experimentally studied at filtering a high-temperature flow of carbon dioxide through it. It was shown that with an increase in the temperature of the filtered gas from 650 to 920 K, the time of urotropine gasification decreased and the average gasification rate increased from 0.38 to 1.25 g/s, leading to an increase in the flow of urotropine gasification products. The maximum achieved value of the mass of urotropine gasification products was 0.8 g per 1 g of incoming gas. In the temperature range of 480-530 K, intensive gasification of urotropine occurred, while the temperature of the gaseous products leaving the reactor remained practically unchanged. The amount of noncondensable gaseous gasification products did not exceed 1% of the initial mass of the sample.

The object of an experimental study is a vapor bubble formed in a subcooled liquid as a result of absorption of laser radiation transmitted into the working volume through a thin optical fiber. Evolution of a bubble is characterized by its rapid growth and collapse with generation of a hot submerged jet. Some features of the process under study are considered in relation to the field of medicine. Normal saline is used as the working fluid. It is shown that under the same conditions (radiation power, optical fiber diameter, and initial temperature of liquid), the dimensions reached by a vapor bubble in saline solution are much smaller than those in pure water. A significant influence of the shape of a fiber tip on the nature of the process under study was revealed.

This paper considers the microwave processing for snow-ice mass comprising the heating and melting stages. The search for basic patterns of these processes aimed to optimization, control and design of stages is based on mathematical models and their implementation using analytical or numerical methods. A nonlinear mathematical model of the two-phase Stefan problem for a layered system of dielectrics was constructed. This approach takes into account the dependences of the medium permittivity and other parameters on the medium temperature and the design of a microwave radiation source.

Thin films of polycrystalline silicon are widely used in semiconductor industry. One of the methods for obtaining such structures on cheap and low-melting substrates is metal-induced crystallization, since the use of a metal (for example, Au) as a catalyst during crystallization of an amorphous semiconductor allows a considerable reduction of annealing temperature. However, the typical duration of metal-induced crystallization is several tens of hours, in contrast to the method of laser-induced crystallization. In the present work, for the first time it is proposed to combine the advantages of the laser-induced and Au-induced crystallization methods. The authors have identified laser-processing modes of thin films of non-stoichiometric silicon oxide (a-SiO_0,1) using nanosecond radiation with a wavelength in the infrared range which ensure the formation of polycrystalline silicon.