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The article presents the results of numerical simulation of the boundary layer of air on a heated surface in the presence of weak acceleration. The numerical model consists of a system of Prandtl equations describing dynamic and thermal processes in the boundary layer, and a κ-ω-γ turbulence model that allows reasonably simulating the laminar-turbulent transition and turbulence suppression. Finite-difference methods were used to solve differential equations. For some calculated cases, the turbulence model was switched off in order to obtain parameters of a known laminar flow. Modeling has shown that in the considered flow conditions, the occurrence and development of a local laminarized region near the wall is possible. In this case, the boundary layer includes the near-wall laminar and external turbulent sections. This nature of the flow leads to a level of friction and heat exchange that correspond to the intermediate flow relative to laminar and turbulent flows under the same conditions.

Known approaches to the determination of flow parameters in the test section of impulse wind tunnels are analyzed, and ways towards their improvement are outlined. An algorithm for calculating flow parameters in short-duration supersonic high-enthalpy wind tunnels using the experimental values of pressure in the prechamber, the total pressure behind the normal shock, and the flow velocity and stagnation temperature as a function of time, is developed. It is shown that the results of measurements and calculations using the developed algorithm for determining flow parameters fairly well comply with the calculations of flow parameters based on the gas-dynamic relations taking into account the losses of heat in the working path of the wind tunnel.

The paper discloses the study of flow crisis in the Ranque-Hilsch vortex tube with a squared cross-section channel. Previous studies have found the conditions for developing the hydraulic crisis for air flow in this type of tube. The crisis phenomenon is related to the event when the longitudinal velocity at the nearwall vortex-circulation zone interface approaches the value of velocity for spreading centrifugal waves along this boundary. The paper presents and discusses the new detail results in measuring the kinematic parameters of the crisis flow, including the parameter of velocity pulsation. The evidences of a hydraulic jump neat the exit of the swirl flow to the tube working channel.

The formation of circulation vortex cells in a liquid medium of a gas-vortex bioreactor has been experimentally studied. The study was carried out in an industrial glass bioreactor with a volume of 10 liters and a reactor vessel diameter D = 190 mm. The vortex motion of air was generated by a paddle wheel (activator) when 50 and 80% of the reactor vessel was filled with the model medium. A 65% water solution of glycerol with density ρ = 1150 кг/м³ and kinematic viscosity ν = 15 мм²/с was used as a model medium. To observe the pattern of vortex motion, the method of particle image velocimetry (PIV) was used. It is shown that when the activator rotates, the meridional and circulation motions of the liquid occur simultaneously. Regularities of the vortex motion of the model medium are determined depending on the reactor filling and the intensity of activator rotation. It is found that the cells of centrifugal circulation appear under the interface; with an increase in the activator rotational speed they develop into the depth of the reactor. It is established that centrifugal circulation of liquid develops similarly as it takes place in a closed vortex flow of one liquid and in a system of limited vortex motion of two immiscible liquids.

An intake has to provide air for the engine uniformly with minimum total pressure loss. Nowadays, regarding the usage of S-shaped intakes, optimization of these ducts has been considered. Uniform distribution of flow at the compressor inlet directly influences the engine performance, and non-uniformity of flow increases surge occurrence possibility. Flow separation along the duct causes a reduction of pressure recovery and engine thrust force. This research has optimized an S-shaped intake to reduce the total pressure loss and flow distortion. The genetic algorithm and artificial neural networks have been combined to decrease the computational cost. Two optimizations, using different conditions, have been studied. In the first case, by modifying centerline coordinates and area ratio of sections, new geometries have been produced, which have caused an improvement of 32.5 % in pressure recovery coefficient and a decrease of 35.8 % in flow distortion. In the second optimization, the shape of each section has also been changed. Super ellipse, egg-shaped and circular profiles are considered as cross sections of the duct. The second optimization has improved the pressure recovery coefficient by 35.5 % and decreased flow distortion by 39.2 %.

Results of numerical simulation of a supersonic (М_∞ = 7) flow past a cylinder with a frontal gas-permeable porous insert (porosity 95%, pore diameter 2 mm) installed at angles of attack α = 0÷10° are reported. The numerical modeling was performed based on the solution of three-dimensional Reynolds-averaged Navier-Stokes equations using three skeletal models: a model of intersecting hollow spheres, a model of non-intersecting hard spheres with a random arrangement of pores, and a model consisting of a set of toroidal elements. The calculated data on the drag coefficients and on the lift force of a cylinder with a frontal gas-permeable high-porosity insert are compared with the results of experiments carried out in the T-327 wind tunnel of ITAM SB RAS. A comparative analysis of the results of using three-dimensional skeletal models of highly porous cellular materials for modeling supersonic flows around bodies with gas-permeable porous inserts installed at various angles of attack is performed.

The density and thermal expansion coefficients of polycrystalline, liquid and amorphous phases of Fe₆₀Co₂₀Si₈B₁₂ alloy in the temperature range of 293÷1650 K have been measured by the monochromatic gamma-ray attenuation technique. The features of crystallization of the melt and amorphous film have been investigated. Reference tables of properties have been developed, their errors have been estimated, and approximation equations have been obtained.

The presented research investigated the thermal diffusivity (α) and the thermal conductivity (λ) of one of the most promising heat-resistant nickel alloys, Inconel 617. The measurements were carried out in the temperature range from 300 to 1475 K using the laser flash method on the LFA-427 setup. The estimated errors of the received data depending on temperature were 2-4% and 3-5% for α and λ, respectively. A comparison with the known literature data was made. The fitting equations for the temperature dependences of the studied properties have been received and a table of reference values has been compiled, which can be used in various engineering and scientific tasks.

The experimental study was performed for a submerged turbulent jet that enters a slot channel with the height of h = 4 mm. The oscillating turbulent jet is generated by a fluidic oscillator with two feedback channels and the exit nozzle with the throat width of d = h . The working fluid is distilled water. The two-component velocity field was acquired using the PIV method with a high resolution up 50 5 kHz. The information was gained about the sweeping turbulent jet (both structure and dynamics) entering a slot channel for the Reynolds number in the range from 1500 to 8000. The jet flow to the slot channel generates large-scale 2D vortex structures. The travel frequency of those structures depends on the jet sweeping frequency produced by a fluidic oscillator. Comparison of the research result with available experimental data demonstrated that for a flow in a slot channel (with geometry h/d = 1) has a smaller angle of jet sweeping. For a higher Re number we observe a variation in distributions of average and pulsation characteristics of the sweeping jet as well as a decrease in the dimensionless jet sweeping frequency.

Experimental data on reconstruction of the spatial structure of a swirl jet in a burner model are presented. An isothermal case of free jet mixing with ambient air at various levels of flow swirl is considered. The high-swirl flows under study are accompanied by the collapse of the vortex core and intense coherent flow pulsations associated with large-scale vortex structures. Experimental data on distributions of axial and tangential velocities were obtained by Particle Image Velocimetry (PIV). The contribution of coherent flow fluctuations to turbulent transport is estimated based on the Proper Orthogonal Decomposition (POD). The frequency of periodic pressure pulsations was measured using acoustic sensors. The frequency of the precessing vortex core (PVC) and the corresponding velocity distributions were measured at a fixed Reynolds number (16500). A nonmonotonic dependence of the Strouhal number on the flow swirl was obtained. The spatial vortex structure was visualized under isothermal conditions. Using POD analysis, it was shown that with an increase in swirl, the precession radius and the pitch of the helical structure of the PVC increase.