An Improved Scaling Model of Buffeting Lift Forces in Air-Water Flows

This paper presents the results of a series of experiments to study the loading of a single rigid cylinder subjected to air-water cross-flow. Five rigid cylinders of same length and different diameters (12.15×10⁻³ m to 31.9×10⁻³ m) were tested over void fractions ranging from 10% to 80%. The fluctuating lift forces on the cylinder are measured and represented in the form of power spectral density. A scaling model of these forces previously developed from one series of experiments with one tube diameter (12.15×10⁻³ m) is tested on these new results by investigating the effect of tube diameter D. Unlike single phase results where the force spectra vary as D³, it is shown that for two-phase flows the force spectra vary as D². The experimental data collapse remarkably well. Both local void fraction and flow regime appear to be sensitive parameters. It confirms the importance of a precise knowledge of the local characteristics of two-phase flows in the study of buffeting forces mechanisms.