Turbulent flow past a transverse cavity with inclined side walls. 1. Flow structure

The process of vortex formation in a cavity with inclined walls, which has a moderate aspect ratio, is experimentally studied, and the distribution of pressure coefficients is measured. The angle of inclination of the side walls ϕ is varied from 30 to 90°. It is found that the flow in the cavity becomes unstable in the range of inclination angles ϕ = 60–70°. Flow reconstruction occurs, which substantially alters the surface-temperature and static-pressure distributions. Large changes in these characteristics and their nonuniform distributions for these angles are observed across the cavity on its frontal wall and on the bottom. For small angles (ϕ = 30 and 45°), the pressure on the rear wall drastically increases, which leads to a small increase in pressure averaged over the entire cavity surface. __________ Translated from PrikladnayaMekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 5, pp. 68–76, September–October, 2006.     

Numerical Study of the Near-Wall Gas-Droplet Jet in a Tube with a Heat Flux on the Surface

A model for calculating the flow of a turbulent mixture of air and suspended liquid particles injected into the near-wall region is developed within a unified approach of mechanics of heterogeneous media in the two-velocity and two-temperature approximation of the Eulerian approach. The influence of droplet evaporation in the near-wall jet on heat transfer between the two-phase gas-droplet flow and the wall is studied in the case of heat addition to the latter. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 1, pp. 5–17, January–February, 2006.     

Some Features of a Turbulent Separated Flow and Heat Transfer Behind a Step and a Rib. 1. Flow Structure

The influence of the shape and size of the obstacle on separated flow and heat transfer is studied experimentally. Results of investigation and comparative analysis of the hydrodynamic structure of a separated flow behind a step and a rib are presented. A principally different character of transfer processes in the separated flow behind obstacles of these types is demonstrated. The flow structure in the secondary vortex region is considered.     

On Scalar Functionals of Nonlinear tensorial Constitutive Equations in the Theory of Plasticity for Nonisothermal Rectilinear Processes of Deformation

Based on base experiments formulated, methods are proposed to specify the scalar functional in the nonlinear equations that relate generalized stresses and finite strains in the theory of plasticity. The base experiments are conducted and the functionals are specified. It is shown that the nonlinear tensorial constitutive equations can be used to describe a nonisothermal process of deformation along a rectilinear path, which is distinct from the base ones, at high temperatures that cause creep strains     

New Crystal Devices for Use at the U-70 Accelerator

JETP Letters - In view of the successful experience in the generation of pion and kaon secondary beams using a focusing crystal, it has been proposed to build at the U-70 accelerator a new-type...     

Robust inverse optimization

Given an observation of a decision-maker’s uncertain behavior, we develop a robust inverse optimization model for imputing an objective function that is robust against mis-specifications of the behavior. We characterize the inversely optimized cost vectors for uncertainty sets that may or may not intersect the feasible region, and propose tractable solution methods for special cases. We demonstrate the proposed model in the context of diet recommendation.     

Specific features of solketal synthesis on KU-2-8 cation-exchange resin

Technological specific features of the solketal synthesis on a KU-2-8 cation-exchange resin were improved. Data are presented on the mutual solubility of the components in the glycerol–acetone–water and glycerol–acetone–water–ethanol systems. It is shown that use of ethanol for homogenization of the starting reagents is more than twice more efficient than performing the process with delivery of an emulsion of the reagents or reaching a full solubility of glycerol in acetone due to the 20-fold excess of the latter at 35°C. It is shown that the delivery of a glycerol emulsion in acetone to an immobile bed of a heterogeneous catalyst working in the falling-film mode leads to flooding of the reactor at spraying densities exceeding 0.15 m³ m^–2 h^–1.     

Electronic structure and phase composition of dielectric interlayers in multilayer amorphous nanostructure [(CoFeB)60C40/SiO2]200

Physics of the Solid State - The multilayer amorphous nanostructure [(CoFeB)60C40/SiO2]200 of alternating composite and dielectric layers was obtained by ion-beam sputtering on a rotating...     

Turbulent mixing of small-obstacle-induced perturbations with the separated shear layer behind a backward-facing step

In the present paper, we consider one of the most efficient and simple methods to additionally intensify the exchange processes and heat transfer in the separated flow behind a backward-facing step. The method uses small obstacles installed upstream the step; such obstacle act as turbulators smaller in size than the main obstacle. As the turbulators, solid mini ribs, comb ribbings, and wall-detached mini ribs were used. Intensification of the turbulent mixing process behind the main obstacle occurs due to the introduction of small-obstacle-induced 2D and 3D perturbations into the separated shear layer behind the step. Results of a detailed experimental study of the distributions of pressure and heat transfer for different heights of the small intensifier and its positions with respect to the step are reported. The influence of intensifier shape on the thermal and dynamic characteristics of the flow has been analyzed. The distributions of pressure and heat-transfer coefficients were used to evaluate the effectiveness of the various mini obstacles and the limits of their action on the drag and heat transfer.