The Photoelectrochemical Activity of Titanium Dioxide Nanosized Films in the Visible Spectral Region

From solutions of organic precursors, nanosized films of titanium dioxide with photoelectrochemical activity in the visible region are obtained. A possibility of photoelectrochemical oxidation of a number of organic compounds under illumination with monochromatic light at a wavelength of 464 nm is demonstrated, which may be due to a decrease in the n-TiO₂ band-gap energy to 2.7 eV.     

A polarization analyzer of optical radiation on the basis of the light diffraction by sound

A device with an acousto-optic polarization splitter as the basic unit has been developed to record polarization-modulated optical signals. It spatially separates input radiation into two beams with mutually orthogonal polarizations. The difference of their intensities serves as the measure of changes in the input-radiation polarization plane. Experiments were performed using a TeO₂ single crystal as the acousto-optic splitter and showed the high efficiency of splitting optical radiation with a wavelength of 0.63 μm in the range of acoustic frequencies of 10–26 MHz.     

Mass transfer between a flat-bottom side cavity and flow in a conduit

A procedure for calculating the concentration in the bottom zone of a flat-bottom side cavity of a conduit during the replacement of one gas by another is developed on the basis of experimental data. The procedure entails the determination of the volumetric flow rates between the gas in the cavity and the gas moving along the main conduit. It is shown that a significant intensification of mass transfer is observed in comparison with pure diffusion transfer for values of the dimensionless group Re^1.2Sc^0.5(l/d)^–0.3>10⁴.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 60, No. 6, pp. 902–907, June, 1991.     

Effect of a Sudden Change in Cross-Sectional Area of the Solid Rocket Motor Duct on Coagulation of Condensed Particles

Results of numerical simulations are reported for two-phase flows with allowance for coagulation and fragmentation of particles of polydisperse condensate in the combustor duct of the solid rocket motor (SRM) with a sudden change in cross-sectional area typical of solid-propellant charges of a complex shape. It is shown that a sudden change in cross-sectional area can lead to a significant (multiple) coagulation-induced increase in the mean particle size. The calculation results are validated by a test series on a model SRM with the use of a laser system for diagnosing particle dispersion.