Experimental study of the effects produced by the changes of the liquid and gas superficial velocities and the surface tension on the interfacial waves and the film thickness in annular concurrent upward vertical flows

2021 ◽  
Vol 120 ◽  
pp. 110224
Author(s):  
Yago Rivera ◽  
José-Luis Muñoz-Cobo ◽  
José-Luis Cuadros ◽  
César Berna ◽  
Alberto Escrivá
Keyword(s):  
Experimental Study ◽  
Surface Tension ◽  
Film Thickness ◽  
Interfacial Waves

Condensation of a Vapor Flowing Inside a Horizontal Rectangular Duct

1995 ◽  
Vol 117 (2) ◽  
pp. 418-424 ◽  
Author(s):  
Q. Lu ◽  
N. V. Suryanarayana
Keyword(s):  
Heat Transfer ◽  
Shear Stress ◽  
Heat Transfer Coefficient ◽  
Film Thickness ◽  
Transfer Coefficient ◽  
Interfacial Shear Stress ◽  
Interfacial Shear ◽  
Rectangular Duct ◽  
Interfacial Waves ◽  
Condensate Film

Condensation of a vapor flow inside a horizontal rectangular duct, using the bottom plate as the only condensing surface, was experimentally investigated. The experimental measurements included condensate film thickness and heat transfer coefficients with R-113 and FC-72. The condensate film thickness, measured with an ultrasonic transducer, was used to obtain the local heat transfer coefficient. The heat transfer coefficient increased with increasing inlet vapor velocity. The rate of increase was enhanced noticeably after the appearance of interfacial waves. Within the limited range of the experimental variables, a correlation between St and RegL was developed by a linear regression analysis. However, because of the effect of the interfacial waves, instead of a single correlation for the entire range of RegL, two separate equations (one for the wave-free regime and another for the regime with waves) were found. Analytical predictions of heat transfer rates in the annular condensation regime require the proper modeling of the interfacial shear stress. A properly validated interfacial shear stress model with condensation is not yet available. The measurement of condensate film thickness at several axial locations opens the door for determining the local interfacial stress and, hence, a model for the interfacial shear stress.

scholarly journals Influence of viscosity, surface tension, and inclination angle on motion of long bubbles in closed tubes

1966 ◽  
Vol 25 (4) ◽  
pp. 821-837 ◽  
Author(s):  
E. E. Zukoski
Keyword(s):  
Experimental Study ◽  
Surface Tension ◽  
Inclination Angle ◽  
Bubble Velocity ◽  
Vertical Tubes

An experimental study has been made of the motion of long bubbles in closed tubes. The influence of viscosity and surface tension on the bubble velocity is clarified. A correlation of bubble velocities in vertical tubes is suggested and is shown to be useful for the whole range of parameters investigated. In addition, the effect of tube inclination angle on bubble velocity is presented, and certain features of the flow are described qualitatively.

Bubble Entrapment in Sprayed Films

2014 ◽  
Author(s):  
A. Dalili ◽  
S. Chandra ◽  
J. Mostaghimi ◽  
H. T. Charles Fan ◽  
J. C. Simmer
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
The Other ◽  
Bubble Motion ◽  
Sauter Mean Diameter ◽  
Glass Substrates ◽  
Buoyancy Forces ◽  
Mean Diameter ◽  
Imagej Software ◽  
Bubble Movement

A compressed air sprayer was used to spray model paint onto two glass substrates at the same time. Afterwards, one glass substrate was placed on a LED light source and still photographs were taken from the top using a DSLR camera with a timer system. The other substrate was put on a balance to record weight. Pictures and weight measurements were taken at 5 second intervals for 15 minutes. The sprayed film thickness was varied. The pictures were analyzed using ImageJ software. Bubble Count vs. Time, Sauter Mean Diameter (SMD) of Bubbles vs. Time as well as Weight vs. Time was plotted. It was seen that the pace of weight loss was faster for thinner films. The rate of bubble escape also depended on film thickness. It took a longer time for thicker films to lose the bubbles entrapped in them. In the first 30 seconds, large bubbles escaped due to buoyancy forces and afterwards surface-tension driven flows became dominant. There was also a lot of bubble movement in thicker films. The effect of gravity was studied as well. Gravity did not affect the bubble escape rate since a downward facing film had the same bubble count as an upward facing film confirming that bubble motion was not due to buoyancy forces alone. However, the SMD of bubbles in a downward facing film was larger than an upward facing film. Buoyancy is not a factor in bubble escape from the downward facing film and only surface-tension driven flows play a role.

Deformation characteristics of ultra-thin liquid film considering temperature and film thickness dependence of surface tension

2011 ◽  
Vol 17 (5-7) ◽  
pp. 983-990 ◽  
Author(s):  
Hiroshige Matsuoka ◽  
Koji Oka ◽  
Yusuke Yamashita ◽  
Fumihiro Saeki ◽  
Shigehisa Fukui
Keyword(s):  
Surface Tension ◽  
Film Thickness ◽  
Liquid Film ◽  
Thin Liquid Film ◽  
Thickness Dependence ◽  
Deformation Characteristics
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