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  • Author or Editor: J. R. Stallabrass x
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Lasse Makkonen
and
J. R. Stallabrass

Abstract

The theory of Langmuir and Blodgett for the droplet collision efficiency was verified by growing rime ice accretions on rotating cylinders in a wind tunnel. The results show that the theory is in excellent agreement with the experimental data in the studied range of mean cylinder collision efficiency from 0.07 to 0.63.

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E. P. Lozowski
,
J. R. Stallabrass
, and
P. F. Hearty

Abstract

A model is described which simulates icing on an unheated, non-rotating cylinder. Both rime and glaze ice can be accounted for. The model computes the thermodynamic conditions and the initial icing rate as a function of angle around the upstream face of the cylinder. Although the model is not time-dependent, the initial icing rate can be used to compute local ice thickness after a specified time interval, and these in turn allow one to plot the ice accretion profile in either a single-step or multi-step fashion. Thus it is possible to predict total ice accretion cross-sectional area and mass for ice grown under varying conditions of airspeed, air temperature and pressure, cloud liquid water content, droplet size distribution, and cylinder size. Results are presented on the stagnation line growth rate as a function of liquid water content and airspeed, and examples of accretion profiles over a range of environmental conditions are provided. Although the model may be applied quite generally, the model results presented here are applicable to aircraft icing conditions.

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E. P. Lozowski
,
J. R. Stallabrass
, and
P. F. Hearty

Abstract

An experimental investigation of icing on non-rotating cylinders, under both wet and dry conditions was undertaken. Airspeeds of 30, 61 and 122 m s−1 appropriate to aircraft icing, liquid water contents of 0.4, 0.8 and 1.2 g m−3 and temperatures of − 15, − 8 and − 5°C, were explored. Dry accretions were lenticular or “spearhead” shapes, while wet accretions tended to develop “horns” and stagnation line depressions as the result of the runback of unfrozen water away from the stagnation line and its subsequent freezing further around the perimeter of the cylinder. Comparisons were made between the experimental accretion shapes and those predicted by the model described in Part I. The model performed best under dry growth conditions. Under wet conditions, the model behavior, while qualitatively correct, was unable to exactly duplicate the details of the accretion profiles. Nevertheless, under both dry and wet conditions, the model predictions of the accretion cross-sectional areas, were quite accurate.

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