КРИЗИС ВЛАСТИ В КАБАРДИНО-БАЛКАРИИ В АВГУСТЕ 1991 ГОДА Статья посвящена исследованию влияния путча 1991 г. на этнополитическую обстановку в Кабардино-Балкарской Республике. Анализируется процесс "включения" национального фактора в разгоревшееся политическое противоборство, вылившееся в кризис власти. Авторами впервые сформулирована и обоснована мысль о том, что события августа 1991 г. привели к объединению к тому времени уже нелояльных по отношению друг к другу национальных движений "титульных" народов Кабардино-Балкарии, что нашло выражение в выдвижении общего требования отставки первых лиц республиканской власти. Адрес статьи: www.gramota.net/materials/3/2017/9/58.html

1991년도 사업경과 보고

/pdf/on-self-propulsion-assessment-of-marine-vehicles-1zahwbqfql.pdf

On self-propulsion assessment of marine vehicles

Investigating the effect of geometric parameters on hydrodynamic and hydro-acoustic performances of submerged propellers

The current paper investigates flow around a blade section of a surface piercing hydrofoil. To this end, a thin wedge section is numerically modelled through an oblique water entry. The flow is numerically studied using a multiphase approach. The proposed numerical approach is validated in two steps. First, pressure and free surface around a wedge entering water are simulated and compared against previously published analytical results. Subsequently, cavitation phenomenon around a submerged supercavitating hydrofoil is modelled and analyzed. It is observed that cavity length, pressure, and lift force are accurately predicted. Subsequently, the main problem has been studied for two different cavitation numbers for a range of advanced ratios equivalent to fully, transition and partially ventilated conditions in order to investigate the effect of ambient pressure on hydrodynamics of the water entry of the foil. The numerical findings reveal that, when the cavitation number decreases, the start of transition mode is postponed and this mode is expanded for the larger range of velocity ratios. This implies that fully ventilated velocity ratio modes are expanded, too. However, in the transition mode, the cavitation number plays an essential role and may lead to a decrease in the pressure difference across the surface piercing hydrofoil which yields a decrease in the resultant force.

/pdf/probing-into-the-effects-of-cavitation-on-hydrodynamic-2s2ryal41t.pdf

Probing into the effects of cavitation on hydrodynamic characteristics of surface piercing propellers through numerical modeling of oblique water entry of a thin wedge

In the present paper, a numerical simulation has been carried out to determine the hydrodynamic characteristics in cavitating viscous flow of the conventional INSEAN E779A propeller in single and tandem configuration by using Singhal et al. cavitation model implemented in FLUENT Software. Firstly, calculations have been carried out on single E779A propeller in non-cavitating and cavitating flows. The computed performances have shown good agreement with experimental data. Next, the numerical approach has been applied in loaded conditions to the case of tandem propeller configurations with respectively 0.2 and 0.6 axial displacement. Results reveal that cavitation is qualitatively well predicted and the cavitation area is rather more pronounced on the fore propeller. Te use of tandem corotating propeller in loaded conditions is highlighted.

/pdf/numerical-simulation-of-the-cavitating-flow-around-marine-co-29ju7858ri.pdf

Numerical simulation of the cavitating flow around marine co-rotating tandem propellers

The present paper deals with the effect of the geometric characteristics on the propeller hydrodynamic performances. Several propeller configurations are created by changing number of blades, expanded area and pitch ratios. The Reynolds-Averaged Navier-Stokes (RANS) equations are solved using the commercial code FLUENT 6.3.26. The standard k−ε and the k−ω SST models are used for the steady uniform and the transient non-uniform ship wake. Overlapping propellers arise from high expanded area involve that the computational domain should be created with several multi-blocks. Thrust, torque and efficiency coefficients of the generated propellers are compared with available experimental data. The computational results reveal that both standard k−ε and k−ω SST models guarantee acceptable level of accuracy in open water condition and unsteady flow predictions. This parametric study has also allowed achieving optimal shape factors ensuring best hydrodynamic performances.

/pdf/effect-of-geometric-configurations-on-hydrodynamic-2gij4ys4mi.pdf

Effect of geometric configurations on hydrodynamic performance assessment of a marine propeller

In the present paper, a numerical simulation based on Kω-SST turbulence model has been carried out to determine the tandem propeller hydrodynamic characteristics in noncavitating viscous flow by using the commercial code Fluent. As the first step, the numerical approach has been applied to the case of single propeller and the comparison with experiment results was in a good agreement. Next, the effects of axial and angular displacement as well as the diameter ratio between the tandem propellers have been investigated. This part of the study reveals that the tandem with idem propeller diameters is strongly recommended to assure more advantages. Furthermore, the tandem geometry corresponding to the axial displacement equal to 0.6D seems to be the best configuration and the open water performances remain almost unchanged with the variation of angular displacement. On the other hand, details of the mutual interaction between tandem propellers were also given by showing pressure contours, streamlines and thrust coefficient. Globally, this study illustrates the advantages of replacing single propellers by tandem solution.

Impact of some geometrical aspects on the tandem co-rotating propeller hydrodynamic characteristics

When the flow of fluid passes through the tubes, part of the energy of the fluid is transmitted to these tubes. The exerted forces on the tubes by the fluid are one of the most important issues because it causes many problems in the systems that include bundles of tubes. The present paper presents an experimental study of a turbulent airflow around nine horizontal cylinders of an in-line tube bundle. One of the cylinders rotates with a speed of 1485 rpm around its axis, and the others are fixed. The purpose of this study is to show the effect of the cylinder rotation on the adjacent cylinders. This study is part of the physical analysis of the turbulent flow around obstacles, fixed or subject to a parietal rotation. The tube bundles was a subject to a series of subsonic wind tunnel experiments (Subsonic Wind Tunnel TE44). The tube test is equipped with a pressure tap placed on the center of the cylinder with a ratio between the tubes P / D = 1.44 (in line), with a variation of the azimuth angle from 0 °to 360 ° with a pitch of 15 °. The results obtained showed that there is a large influence of rotational movement of the cylinder on the other adjacent cylinders, so there are different excitation forces on the tube for the different positions within the bundle as well as deformation of the tube due to the pressure forces exerted on the latter. 

Experimental investigation of drag reduction by Rotational tube in a tube bundle

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Papers

Effect of geometric configurations on hydrodynamic performance assessment of a marine propeller

Numerical simulation of the cavitating flow around marine co-rotating tandem propellers

Impact of some geometrical aspects on the tandem co-rotating propeller hydrodynamic characteristics

Experimental investigation of drag reduction by Rotational tube in a tube bundle