The present work has been carried out to investigate on the average void fraction of gas/non-Newtonian
fluids flow in downward inclined pipes. The influences of pipe inclination angle on the average void fraction
were studied experimentally. A simple correlation, which incorporated the method of Vlachos et al.
for gas/Newtonain fluid horizontal flow, the correction factor of Farooqi and Richardson and the pipe
inclination angle, was proposed to predict the average void fraction of gas/non-Newtonian power-law
stratified flow in downward inclined pipes. The correlation was based on 470 data points covering a wide
range of flow rates for different systems at diverse angles. A good agreement was obtained between theory
and data and the fitting results could describe the majority of the experimental data within ±20%.