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

Abstract

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 (12.15×10−3 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.