DEVELOPMENT OF A TOTAL LIQUID WATER CONTENT PROBE

This paper reports on the development and calibration of a prototype probe for measuring the liquid water content of Appendix C and SLD icing cloud conditions. The conceptual design was based on a total pressure probe, water collector and suction fan. The water droplet mass that was collected iso-kinetically by the probe was weighed, and the LWC was determined from the water mass and volumetric air drawn into the probe. Initial effort had concentrated on the evaluation of different methods of capturing and storing water droplets that entered the probe. Different types of the adsorbent materials were installed into a detachable water collector to remove water droplets from an ingress water cloud via adsorption e.g. water adsorbent and blotter papers, silica gel and molecular sieve desiccants and hydrophobic B-Gon fiber mesh. The basic test methodology was to inject a known amount of water directly into the probe inlet and comparing this to the amount adsorbed by the water collector. Tests conducted in a laboratory showed that collection efficiencies of 100.8 ± 8% for LWC between 0.5 and 4.0g/m 3 were obtained. The iso-kinetic function of the probe was tested successfully in the wind tunnel at velocities between 105 and 130mph. Iso-kinetic condition was attained within 3 seconds of engaging the suction fan of the probe. NOMENCLATURE