Evgeny Anavitolievich Chinnov

Regimes of two-phase flow in micro- and minichannels (review)

The review deals with the analysis of the factors affecting the boundaries of two-phase regimes in the channels of different cross sections, whose minimal size is less than the capillary constant. The channels are classified by size. Data for two-phase flow regimes are systematized and summarized in tables for the round and rectangular tubes. It is indicated that the most studies identify the following two-phase flow regimes: bubble, slug and annular. The regimes found in some papers are described. The terminology used to describe the regimes is kept. Here we analyze the main factors affecting the structure of the two-phase flow, such as gas and liquid flow rates, parameters of the channel and input section, wettability of the inner surface of channels, liquid properties, and gravitational forces. It is shown that development of instability of the two-phase flow has a significant impact on formation, evolution, and change of the flow regimes.

Study of gas-water flow in horizontal rectangular channels

The two-phase flow in the narrow short horizontal rectangular channels 1 millimeter in height was studied experimentally. The features of formation of the two-phase flow were studied in detail. It is shown that with an increase in the channel width, the region of the churn and bubble regimes increases, compressing the area of the jet flow. The areas of the annular and stratified flow patterns vary insignificantly.

Formation of thermocapillary structures in a heated liquid film

The conditions of formation of a three-dimensional thermocapillary structure on the surface of a liquid film flowing along a heater with the constant temperature were studied numerically based on the derived system of equations. Formation of the thermocapillary structure was modeled by periodic perturbations in the transverse direction superimposed on the two-dimensional flow. It is shown in calculations that transversal perturbations can develop into periodic rivulet structures on the film surface if the Marangoni number exceeds some threshold value. It is revealed that the rivulet structure develops when the period belongs to a certain range, which is determined by the value of Marangoni number. The results of calculations are in a good agreement with experimental data.

Features of two-phase flow in a rectangular microchannel with the height of 300 μm

The two-phase flow in a narrow short horizontal channel of rectangular cross section with the width of 10 mm and height of 300 μm was studied experimentally. The features of the jet regime were studied in detail. It is shown that an increase in superficial velocity of jet pulsation frequency increases, and the ratio of unwetted area of the upper channel wall to the wetted area of the upper channel wall decreases.

Combustion of n-butanol in a flat minichannel

Combustion of n-butanol was studied experimentally at the two-phase flow in a rectangular channel of 4-mm height. Characteristics of the two-phase flow in channels with close configuration were analyzed, and the conditions of flame spread in the channel were determined. The dependencies of flame propagation velocity on flow velocity of the gas mixture with different oxygen contents were measured.