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 influence of diameter on the loading of a single rigid cylinder subjected to air-water cross-flow. Five rigid cylinders of same length and different diameters (⁠$12.15×10−3m$ to $31.9×10−3m$⁠) 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 $(12.15×10−3m)$ 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.