Droplet distribution spectrum effects on dry ice growth on cylinders

Abstract

A detailed parametric analytical study along with a series of viscid multiphase numerical simulations of ice accretion were performed in comparison with experimental data of ice accretion on a 30 mm diameter cylinder. The study was performed for droplet distribution spectra, Langmuir (A-J), in addition to an experimental droplet distribution obtained in an icing tunnel. Analysis shows that droplet distribution spectrum has a pronounced effect on cloud impingement parameters, such as droplet overall collision efficiency (E), droplet local collision efficiency (β0), droplet maximum impingement angle (θ), droplet impact velocity (V0), accreted ice mass and density. The values of these parameters can significantly change at the same operating conditions and median volume diameter (MVD) with a change of droplet distribution spectrum. These differences are more pronounced at low values of droplet inertia parameter, (K). Further experimental, analytical and numerical investigations into those aspects at lower values of droplet inertia parameter are deemed necessary in order to expand the understanding of different cloud impingement parameters on the ice accretion process and performance of current icing theory in cases with low values of K. For the low values of K, which correspond to the values of E ≤ 0.10, the use of the full droplet spectrum is recommended in calculations instead of monodispersed. In addition, based on the results of this and previous works the Langmuir D distribution is recommended as standard or “first guess” distribution.