FEATURES OF ISOTHERMAL MULTICOMPONENT MIXING OF GAS MIXTURES CONTAINING METHANES AT CONVECTIVE INSTABILITY

The features of the change in the regimes "diffusion-gravitational concentration convection" in isothermal ternary gas mixtures have been studied experimentally and numerically. It is shown that, at a certain pressure, due to the difference in the diffusion coefficients of the components, an instability of mechanical equilibrium arises, leading to the appearance of structured convective formations. Calculation results are compared with experimental data on the location of the instability boundaries in the studied gas mixtures. Intensity of convective mixing is also influenced by the content of the component with the highest molecular weight in the initial mixture. In terms of Rayleigh numbers, a boundary relation is obtained that determines the regime change. The solution of the problem of multicomponent mixing in a cylindrical vertical channel of finite height with solid and impermeable boundaries for the substance made it possible to determine the concentration distribution along the length.

Partial Lubrication of Full Cylindrical Bearings

The phenomenon of cavitation in bearings is often studied under the assumption that the pressure and the pressure gradient both vanish along the unknown boundary of the cavitation bubble. However, such conditions (often named after Swift and Stieber) may be inconsistent with mass conservation. The discrepancy is particularly striking when the case of long bearings is studied within the so called Sommerfeld approximation. Therefore a complete analysis of the Sommerfeld case is carried out here again (in particular condition of starving feed are examined) under a hypothesis which allows mass-conservation and leads to a boundary relation of the Jakobson type.