Instability of a liquid film moving under the effect of gravity and gas flow

1996 ◽  
Vol 22 ◽  
pp. 116
Author(s):  
S Alekseenko
Keyword(s):  
Liquid Film ◽  
Gas Flow

Annular Liquid Film Flow Under Local Heating in Microchannel

2005 ◽  
Author(s):  
Elizaveta Ya. Gatapova ◽  
Vladimir V. Kuznetsov ◽  
Oleg A. Kabov ◽  
Jean-Claude Legros
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Biot Number ◽  
Gas Flow ◽  
Film Flow ◽  
Local Heating ◽  
Local Heat Transfer ◽  
Flow Region ◽  
Local Heat ◽  
Liquid Film Flow

In our previous investigations the formation of liquid bump of locally heated laminar liquid film with co-current gas flow was obtained [1,2]. The evaporation of liquid was left out of account. Heat transfer to the gas phase was approximately specified by a constant Biot number [2,3]. The aim of this work is an investigation of the evaporation effect, the hydrodynamics and the heat transfer of liquid film flow in a channel 0.2–1 mm height. The 2-D model of locally heated liquid film moving under gravity and the action of co-current gas flow with low viscosity in a channel are considered. The channel can be inclined at an angle with respect to horizon. It is supposed that the height of the channel is much less than its width. Surface tension is assumed to depend on temperature. The velocity profiles for gas and liquid regions are found from problem of joint motion of isothermal non-deformable liquid film and gas flow. Using the findings the joint solution of heat transfer and diffusion problem with corresponding boundary condition is calculated. Having the temperature field in the whole of liquid and gas flow region we find a local heat transfer coefficient on the gas-liquid interface and Biot number as a function of flow parameters and spatial variables.

The Thermocapillary Convection in Locally Heated Laminar Liquid Film Flow Caused by a Co-Current Gas Flow in Narrow Channel

2003 ◽  
Author(s):  
E. Y. Gatapova ◽  
Y. V. Lyulin ◽  
I. V. Marchuk ◽  
O. A. Kabov ◽  
J.-C. Legros
Keyword(s):  
Free Surface ◽  
Analytical Solution ◽  
Liquid Film ◽  
Gas Flow ◽  
Surface Deformation ◽  
Plane Channel ◽  
Film Surface ◽  
Local Heat ◽  
Narrow Channel ◽  
Liquid Film Flow

A two-dimensional model of a steady laminar flow of liquid film and co-current gas flow in a plane channel is considered. It is supposed that the height of a channel is much less than its width. There is a local heat source on the bottom wall of the channel. An analytical solution for the temperature distribution problem in locally heated liquid film is obtained, when the velocity profile is linear. An analytical solution of the linearized equation for thermocapillary film surface deformation is found. A liquid bump caused by the thermocapillary effect in the region where thermal boundary layer reaches the film surface is obtained. Damped oscillations of the free surface may exist before the bump. This is obtained according to the solution of the problem in an inclined channel. It depends on the forces balance in the film. The defining criterion is found for this effect. The oscillations of free surface do not exist for horizontally located channel.

Turbulence Structures in Horizontal Two-Phase Flows Under Counter-Current Conditions

2006 ◽  
Author(s):  
Thomas D. Sta¨bler ◽  
Leonhard Meyer ◽  
Thomas Schulenberg ◽  
Eckart Laurien
Keyword(s):  
Liquid Film ◽  
Test Section ◽  
Gas Flow ◽  
Second Phase ◽  
Two Phase Flows ◽  
Two Phase ◽  
Flow Rates ◽  
Local Measurements ◽  
Counter Current ◽  
Film Flows

In order to improve the multi-dimensional numerical simulation of horizontal two-phase flows, the knowledge of local turbulent quantities is of great importance. In horizontal stratified flows, the denser (first) phase flows as a film beneath the other (second) phase. Under counter-current conditions, the second phase flows into the opposite direction of the first phase. In the present investigations a liquid film flows counter-currently to a gas flow. According to the flow rates of both phases, different flow regimes set in. In supercritical flows (Fr>1), the height of the liquid film increases in flow direction, while it decreases in subcritical flows (Fr<1). For sufficiently high gas flow rates the upper part of the liquid film flows into direction of the gas flow, while the lower part still flows into its initial direction opposite to the gas flow. Only a reduced amount of water reaches the end of the test section. This flow regime is referred to as partially reversed flow. The presented local measurements provide not only the mean and rms-velocities of the liquid film, but also the corresponding Reynolds stresses. Local measurements are carried out at two different positions along the test section for various boundary conditions. Furthermore, the liquid injection height has been varied. The kinematic and turbulent structures of the different flow patterns are presented and compared.

scholarly journals The Effect of a Flat-plate-Type Obstacle on the Thin Liquid Film Accompanied by a High Speed Gas Flow

1989 ◽  
Vol 3 (4) ◽  
pp. 389-404
Author(s):  
Tohru FUKANO ◽  
Katsuhiko KADOGUCHI ◽  
Mikio KANAMORI ◽  
Akira TOMINAGA
Keyword(s):  
Liquid Film ◽  
Flat Plate ◽  
High Speed ◽  
Gas Flow ◽  
Thin Liquid Film ◽  
Plate Type

scholarly journals Simulation of the flow of a two-layer liquid film on a cylindrical surface

2018 ◽  
Author(s):  
I. S. Tonkoshkur ◽  
T. E. Zaytseva
Keyword(s):  
Circular Cylinder ◽  
Liquid Film ◽  
Gas Flow ◽  
Plane Surface ◽  
Fluid Model ◽  
The Body ◽  
Polar Coordinates ◽  
Zero Approximation ◽  
Physical Parameters ◽  
Optimal Effect

The problem of a stationary joint flow of a two-layer liquid film and gas along the outer (or inner) surface of a circular cylinder of radius r0 is considered. It is assumed that the films are insoluble in one another, and there are no chemical reactions. The axis of the body is located vertically, and the films flow down from its top. The film is affected by gravity, as well as a gas stream directed upwards or downwards. A cylindrical coordinate system (r, θ, z) is introduced: the z coordinate is measured along the axis of the cylinder, r and θ are the polar coordinates in a plane perpendicular to the axis of the body. To describe the flow of a liquid film, a viscous incompressible fluid model is used, which is based on the equations of continuity and Navier-Stokes. The following boundary conditions are set on the interface surfaces: on the solid surface - draw off “sticking”, on the “liquid-liquid” and “liquid-gas” interfacial surfaces - the conditions of equilibrium of forces and continuity of speeds. To simplify these differential equations, the method of a small parameter, for which the relative thickness of the films is selected, is applied. Solutions of simplified equations (in a zero approximation) are obtained in analytical form. Functional dependences are obtained for calculating the optimal effect of the gas flow on the "working" film. In accordance with the described method, calculations of the flow of a two-layer film on the outer and inner surfaces of the circular cylinder are performed in cases where the gas stream is directed upwards, downwards , and also when the gas flow is absent. An increase in the relative thicknesses of the films δ1 and δ2 (with decreasing radius of the cylinder r0) leads to an increase in deviations from the case of a plane surface that corresponds to the limiting case δ1 = δ2 = 0. The results of calculations of the flow of a two-layer liquid film on the surface of a circular cylinder are presented. The analysis of the influence of physical parameters on the speed profiles is carried out. The results of calculations for determining the optimal effect of gas flow on a liquid film are presented, when the profile of the speed of the "working" film is the most uniform

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