Calculation of Frictional Pressure Drop of Annular Flow in Rolling Vertical Tubes

The calculation of the pressure drop of annular flow in rolling vertical tubes with three different diameters was studied.Based on separated flow model,it was found that calculations of annular flow frictional pressure drop with conventional Chisholm C-value were higher than the experimental data.Through the analysis,the Chisholm C-value under rolling condition was shown to decline exponent with the increase of slip ratio,then the correlation for C-value under rolling condition was proposed on the basis of the experimental data.Applying the new proposed correlation for C-value to separated flow model,it was shown that the calculations of annular flow frictional pressure drop correlated well with experimental data.