ANALYSIS OF COUNTERCURRENT LIQUID-VAPOR INTERACTIONS AND THE EFFECT ON THE LIQUID FRICTION FACTOR

A closed mathematical model of the liquid friction factor for flow occ urring in triangular grooves is presented. The model considers the int erfacial shear stresses due to liquid-vapor frictional interactions fo r countercurrent flow. Using a coordinate transformation and the Nacht sheim-Swigert iteration scheme, a method is developed by which the as ymptotic, two-point boundary value problem with one point-value varyin g can be solved. The coordinate transformation provides a means by whi ch the irregular cross section of the liquid flow can be changed into a regular shape, which can then be solved numerically. The solution yi elds the velocity distribution for countercurrent liquid-vapor flow an d allows the governing liquid flow equations to be solved for cases wh ere the liquid surface is strongly influenced by the vapor flow direct ion and velocity. To verify the analytical results, an experimental te st facility was constructed. The numerical solutions for channel angle s of 20 degrees, 40 degrees, and 60 degrees are compared with the corr esponding experimental data and found to be in good agreement.