Turbulent Events and Gas-Side Mass Transfer Coefficients in a Wavy Air-Water Stratified Flow

Document Type : Research Article


Faculty of Chemical Engineering, Isfahan University of Technology, Isfahan, I.R. IRAN


Turbulence structure on the gas side of a wavy stratified flow was experimentally investigated in a near horizontal 18.7 cm (H) 10 cm (W) 5.5m (L) rectangular duct.By applying the Variable Interval Time Averaging (VITA) technique to the hot wire anemometer measurements frequency of occurrence of turbulent events were detected near the air-water interface. Experimental results showed that frequency of occurrence of turbulent events over the waves increased with the interfacial shear at the interface. Mass transfer coefficients were calculated making use of eddy cell model and calculated turbulent event frequencies. Predicted mass transfer coefficients show good agreement with experimental correlation. Conditional averages of turbulent events were obtained by applying VITA technique to the measured instantaneous velocities. Despite near wall region, both ejection and sweep can initiate turbulent event at the interface.


Main Subjects

[1] McCready M.J., Hanratty T.J., Effect of Air Shear on Gas Absorption by a Liquid Film, AIChE J., 31(12),
p. 2006 (1985).
[2] Lim I.S., Tankin R.S., Yuen M.C., Condensation Measurements of Horizontal Cocurrent Stream/ Water Flow, ASME J.Heat Transf., 106, p. 425, (1984).
[3] Kim H.J., Lee S.C., Bankoff S.G., Heat Transfer and Interfacial Drag in Counter Current Steam-Water Stratified, Int. j. Multi Phase Flow, 11(5), p. 593, (1985).
[4] Komori S., Nagaosa R., Murakami Y., Turbulence Structure and Mass Transfer Across a Sheared Air-Water Interface in Wind-Driven Turbulence, J.Fluid Mech, 249, p. 161 (1993).
[5] Lorencez C., Nasr-Esfahany M., Kawaji M., Ojha M., Liquid Turbulence Structure at a Sheared and Wavy Gas-Liquid Interface, Int.J.Multiphase Flow, 23(2), p. 205 (1997).
[6] Sakai Y., Watanabe T., Kamoara S., Kushida T., Nakamura I., Simultaneous Measurements of Concentration and Velocity in a CO2 Jet Issuing into a Grid Turbulence by Two Sensor Hot Wire Probe, Int. J. of Heat and Fluid Flow,22, p. 227 (2001).
[7] Narayanan S., Barooah P., Cohen J.M., “Experimental Study of the Coherent Structure Dynamics and Control of an Isolated Jet in Cross Flow”, 40th Aerospace Science Meeting and Exhibit, United Technologies Research Center, January 14-17, (2002).
[8] Klipp C., Mahrt L., Conditional Analysis of an Internal Boundary Layer, Boundary Layer Meteorology, 108, p. 1 (2003).
[9] Bruun H.H., "Hot Wire Anemometry, Principles and Signal Analysis",OxfordUniversityPress,Oxford,New York, , pp. 99 (1996).
[10] Blackwelder R.F., Kaplan R.E., On the Wall Structure of the Turbulent Boundary Layer, J. Fluid Mech, 76, p. 89 (1976).
[11] Kowalski J.E., “Wall and Interfacial Shear Stress in Stratified Flow in a Horizontal Pipe”, AIchE Ann. Meet.,San Francisco, (1984).
[12] Lorencez  C.,  Nasr-Esfahany  M.,  Kawaji  M., “Investigation of Turbulence Structure and Prediction of Interfacial Heat and Mass Transfer in Wavy Stratified Flow”, AIChE J., 43, p. 1426 (1997).
[13] Treybal  R.,  “Mass  Transfer  Operations", 3rd. ed., McGraw-Hill Inc,Singapore, (1980).