Hydrogas dynamics of metal refining in intermediate ladles

A three-dimensional model is proposed for the hydrogas-dynamic phenomena within the intermediate ladle of a continuous-casting machine. The results—the distribution of the current function and the velocity field—permit quantitative estimation of the increase in the transfer coefficient at the slag-metal boundary. These data may be used in intermediate-ladle design. By this means, the content of nonmetallic inclusions in continuous-cast billet may be significantly reduced.     

Effect of metal coating on the optical losses in heated optical fibers

The effect of heating in air on the optical losses in metal-coated fibers has been studied. Two fibers were drawn from the same silica preform and coated by different metals (copper and aluminum). Dependences of a change in the optical losses on the temperature were measured in a 20–400°C range at a 50°C step. The optical losses of metal-coated fibers heated to temperatures below 300°C change mostly due to the microbending contribution. At temperatures above 300°C, the main contribution to increasing optical losses is due to the absorption on OH groups. It is established for the first time that the contribution to optical losses due to the OH groups is much more pronounced in Al-coated fibers than in Cu-coated ones. In addition, the Al-coated fibers exhibit growth in the optical losses above 300°C due the absorption on molecular hydrogen.     

Numerical analysis of the wind regime in the neighborhood of Pulkovo airport

The wind field in the neighborhood of Pulkovo airport is investigated by numerically solving the Reynolds equations by the finite-volume method, closed by means of the dissipative two-parameter turbulence model, and using multilayer near-wall functions.     

Reducing the influence of a transition process in field calibration of hydrophones at low frequencies with the use of quadrature-added harmonic signals

A method of reducing the signal settling time in a transmitter–receiver system in field calibration of a hydrophone at low frequencies in a non-anechoic water tank based on correction of the radio frequency response is considered. The advantage gained with the use of the radiation of quadrature-added harmonic signals in precise low-frequency calibration of hydrophones by comparison with pulse-tone radiation is demonstrated.     

MCVD of fluorosilicate glass

Preforms with a fluorosilicate glass core produced by the modified chemical vapor deposition process with SiF₄ as the fluorination agent were used to study the effect of initial vapor mixture composition on the refractive-index difference Δn between the fluorosilicate and silica glasses and the glass deposition rate. The results indicate that Δn can reach about −0.01. The marked reduction in the deposition rate of fluorosilicate glass with increasing SiF₄ concentration seems to be due to chemical reactions that lead to the formation of stable gaseous chlorofluorosilanes.     

Verification of the Multiblock Computational Technology in Calculating Laminar and Turbulent Flow around a Spherical Hole on a Channel Wall

A methodological numerical investigation of the three-dimensional flow of an incompressible viscous fluid around a deep spherical hole on a channel wall has been carried out within the framework of the multiblock approach on the set of intersecting rectangular and cylindrical grids.