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In the vicinity of a semicircular airfoil with slot suction of air provided with a 0.2-diameter (chord) vortex cell installed on the backside of the wing, at low speeds and zero angle of attack the pattern of the unsteady separated airflow undergoes substantial changes, those changes being accompanied with the displacement of flow separation point toward the trailing edge. The slot suction of air and its blowout into the near wake in such an airfoil is organized using a discharge channel with a fan; from this channel, the air jet is discharged into atmosphere tangentially to the airfoil base, with the pressure drop in the fan being equal to twice the pressure head. Under such conditions, the integral force characteristics of the wing show dramatic changes: the lift force, initially being ultra-low negative, becomes positive, and the drag decreases two-fold. The static pressure decreases by two or three times on the upper arch of the profile, and it increases by two times on the lower part of the airfoil, the level of pressure pulsations decreasing by more than ten times.

A technique for designing the supersonic annular inlets with isentropic deceleration surfaces is considered. The contour of an isentropic supersonic nozzle constructed by the method of characteristics for an inviscid gas flow with given uniform parameters at the inlet and at the outlet is used as the basic configuration of the inlet. The reversed flow of a viscous gas is computed with the aid of numerical techniques in the contour under consideration and the real operational characteristics of the obtained inlet of a fixed geometry are determined in the range of the conditions of its application. In the process of computations, the minimum cross-sectional sizes are selected, which ensure the inlet start without a detached bow shock at the entrance.

The decay of a far wake and its turbulent fluctuations behind two thin discs of the same diameter D, oriented normal to the incident flow, have been studied using the Particle Image Velocimetry (PIV). The experimental study was carried out in a water flume (Re ≈ 2⋅10⁵) with varying distances between the discs (L_x = 4–8D) and their axes shift relative to each other (0, 0.5D and 1D). It is found that the velocity deficit behind two discs depends weakly on L_x, and at L_х > 40D, it becomes indistinguishable from the level of turbulent fluctuations of the incident flow. It is found that the decay of the average velocity deficit and its turbulent fluctuations in a wake of a tandem of discs can be described by the same analytical dependence with exponent -2/3 as for the wake decay of a single disc. However, at the same distance downstream, the value of deficit behind two discs is substantially higher than the corresponding value behind a single disc. Velocity fluctuations in a far wake behind a pair of discs depend weakly on longitudinal dimension L_x, but at the same time, in contrast to the velocity deficit, their level does not differ significantly from the level of fluctuations behind a single disc.

Numerical analysis of the swirling turbulent wake degeneration past a self-propelled body has been carried out. It has been shown that starting from the distances of the order of 100 diameters from the body, the flow becomes prac-tically shearless. A simplified mathematical model of the far swirling wake past a self-propelled body has been constructed.

The results of the numerical modeling of turbulent structure of the penetrating convection above the urban heat island with a small aspect ratio in a stably stratified medium at rest are presented. The gradient diffusion representations for turbulent momentum and heat fluxes are used, which depend on three parameters - the turbulence kinetic energy, the velocity of its spectral expenditure, and the dispersion of temperature fluctuations. These parameters are found from the closed differential equations of balance in the RANS approach of turbulence description. The distri-butions of averaged velocity and temperature fields as well as turbulent characteristics agree well with measurement data.

The results of numerical simulation of the structure of non-isothermal polydisperse bubbly turbulent flow and heat transfer behind a sudden tube expansion are presented. The study was carried out at a change in the initial dia-meter of the air bubbles within d_m1 = 1–5 mm and their volumetric void fraction β = 0–10 %. Small bubbles are available in almost the entire cross section of the tube, while the large bubbles pass mainly through the flow core. An increase in the size of dispersed phase causes the growth of turbulence in the liquid phase due to flow turbulization, when there is a separated flow of liquid past the large bubbles. Adding the air bubbles causes a significant reduction in the length of the separation zone and heat transfer enhancement, and these effects increase with increasing bubble size and their gas volumetric flow rate ratio.

There are various matching ways between turbocharger and engine, the variable nozzle turbine is the most significant method. The turbine design must be economic with high efficiency and large capacity over a wide range of operational conditions. These design intents are used in order to decrease thermal load and improve thermal efficiency of the engine. This paper presents an original design method of a variable nozzle vane for mixed flow turbines developed from previous experimental and numerical studies. The new device is evaluated with a numerical simulation over a wide range of rotational speeds, pressure ratios, and different vane angles. The compressible turbulent steady flow is solved using the ANSYS CFX software. The numerical results agree well with experimental data in the nozzleless configuration. In the variable nozzle case, the results show that the turbine performance characteristics are well accepted in different open positions and improved significantly in low speed regime and at low pressure ratio.

The paper presents results of computer simulation of the film cooling on the turbine blade leading edge model where the air coolant is supplied through radial holes and row of cylindrical inclined holes placed inside hemi-spherical dimples or trench. The blowing factor was varied from 0.5 to 2.0. The model size and key initial parameters for simulation were taken as for a real blade of a high-pressure high-performance gas turbine. Simulation was performed using commercial software code ANSYS CFX. The simulation results were compared with reference variant (no dimples or trench) both for the leading edge area and for the flat plate downstream of the leading edge.

The focus of this numerical study is to conceive a new basic film cooling configuration in order to increase film cooling effectiveness, especially at the leading edge zone between the injection holes where cooling is mostly needed. The new configuration, resulting from the tangential slot configuration and especially adapted to the leading edge of an asymmetrical blade, is compared to the uniform slot configuration. Three alternatives geometries were proposed and numerically tested to find the configuration that provides the best film cooling effectiveness. The simulation is conducted at a fixed density ratio of 1.0 and a blowing ratio of 0.7. A new parameter, Rc, is defined to measure the rate of blade coverage by the film cooling. The outcomes of the numerical results indicate that the three proposed configurations allow better thermal protection because of their higher film cooling coverage. At suction side, the new configurations provide a better film cooling coverage than the baseline case. The minimal improvement is at approximately 34%, with a light superiority of case 1. At pressure side, the use of the tangential slot is especially interesting for the allowed minimum adiabatic effectiveness values between 0.3 and 0.5.

The paper presents experimental data for production of a coating using cold gas dynamic spraying with a mask with transverse size in the range 0.3-1 mm and placed at different distances from the substrate. The coated samples were produced, and coating profiles were measured in the vicinity of the masked zone. The tests with depositing of aluminum powder and copper powder demonstrated that the distinct profile of masked zone is obtained for placing the mask at a distance below critical (depending of spray conditions). The most accurate boundary of the masked zone takes place at a minimal distance (depends on the coating thickness). Depending on the spraying conditions, the increase in the mask-substrate distance may result either in monotonic decline of the masked zone width or a slight increase for a certain range. Experimental data are generalized by normalizing with the transverse size of the mask (under other equal conditions).