A. V. Bobylev

Formation of rivulets in isothermal liquid film flow during transition to a three-dimensional wave regime

We present the results of an experimental investigation of the transition from a two-dimensional to three-dimensional (3D) flow in a liquid film flowing down a vertical plate of large dimensions. It is established that this transition is accompanied by the formation of rivulets. At large distances from the initial region, the wave regime can be almost completely suppressed in inter-rivulet regions.

Rivulet flow on the outer surface of an inclined cylinder

A study of the three-dimensional flow of a liquid film (rivulet) over the external part of an inclined cylinder was conducted for liquids with various physical properties. Patterns of the flow regimes were constructed. Good agreement is observed between the experimental data on the thickness and wall friction with the calculation with an asymptotic model in the case of a waveless rivulet. A comparison of the evolution of natural waves on rivulets with the theory of waves of maximal growth shows good agreement for small Re numbers. During the experiments, the wave characteristics of excited waves on a rivulet were investigated. The thickness, amplitude, frequency, and phase velocity of the waves over a wide range of variable parameters are given. Phase velocity integrated functions of the amplitude are constructed for various liquids. The friction on the cylinder wall is measured in the presence of natural and excited waves. The effects of wave regimes on the average values and RMS (root-mean-square) friction pulsations are studied.

The influence of aluminum anode alloys and alkaline electrolyte composition on performance of aluminum-air cells for portable applications

The influence of the composition of alkaline electrolyte and some anode alloys on performance of cells of aluminum-air power sources without electrolyte regeneration and circulation circuits is investigated in order to elaborate proposals for construction of portable sources. It is shown that with pure aluminum anodes, the cell capacity grows with increasing electrolyte concentration; At the same time, the use of potassium electrolytes with the same molar concentration as that of sodium electrolytes at lower electrolyte temperatures yields a considerable gain in specific capacity of cells. The use of aluminum alloys doped with indium and gallium or bismuth and gallium permits one to increase the specific capacity of cells with sodium electrolyte by 100–150 A·h per liter of electrolyte in a wide range of concentrations and at various electrolyte temperatures.

On the peculiarities of work of promising anode alloys for portable aluminum-air current sources

Peculiarities of Work of promising anode alloys for portable current sources, referred to Al-In-Ga and Al-Sn-Ga systems, are considered. The use of such alloys makes it possible to increase specific energy of portable aluminum-air current sources (AA CSs) without external service circuits by a factor of 2.5–3 compared to the two-component alloys proposed in the literature. The use of anodes of promising alloys in aluminum-air current sources with flow-through cells and an external electrolyte regeneration circuit appreciably simplifies restart of the source after long continuance in the no-load condition.

Flow structure in three-dimensional waves on a vertically falling liquid film

We have simultaneously measured the velocity vector and film thickness fields in three-dimensional (3D) waves formed upon the decay of regular 2D waves on a liquid film flowing down a vertical plate. Velocity fields at various distances from the plate surface in various regions of a 3D wave are constructed. It is shown that the liquid flow in the wave has a complex structure with regions of backflow and spanwise streams, which mainly occur under the main crest of the wave.

Rivulet dynamics at isothermal film flow

Averaged fields of thickness of an isothermal vertically flowing liquid film, obtained by the laserinduced fluorescence method, have been analyzed. The chosen minimum averaging time interval, at which the wave motion is completely averaged, allows one to observe rivulet dynamics in a transverse direction. It is found that short-lived rivulets, which are chains of no less than five to eight waves with similar transverse coordinates, are dominant structures on the film surface at Reynolds number Re > 50.