An Appraisal of the Single Rotating Cylinder Method of Liquid Water Content Measurement

The theory of the single rotating cylinder method of liquid water content measurement is reviewed with particular emphasis on the various sources of possible error. The errors, although shown to be relatively small, may be reduced by taking into account the growth of the cylinder diameter resulting from the accreted ice, by employing a realistic value of ice density, and by using the actual median volume diameter of the droplet spectrum if this is known. Revised graphs for use with this method are presented. Comparative tests in an icing wind tunnel between the rotating cylinder method and another blade method showed substantial agreement, thus giving confidence in the veracity of this method of liquid water content measurement.