Simulated Atmospheric Rime Icing of Some Wind Speed Sensors

Abstract

Four commercially available wind speed sensors have been tested in an icing wind tunnel to determine the relative susceptibility of each to atmospheric icing and to determine the influence of ire accumulations upon the operation and accuracy of each. A comparison of relative susceptibility to icing was carried out on the basis of an average collection efficiency. A clear advantage of the large sensors over the smaller ones was found. The operation of each sensor is affected by ice accretion in three specific ways. These are (i) interference between ice on the support structure and the hub of the rotating assembly, (ii) growth of ice from the support into the volume swept by the rotating assembly, and (iii) a change in cup shape. An estimate of an ?effective? operating time under expected icing conditions was made. Results of this calculation indicate the useful operating life is only an the order of hours.