Simulation of a Bi-modal Large Droplet Icing Cloud in the NASA Icing Research Tunnel

Abstract

‡† ‡ ‡ An experimental effort was recently undertaken to simulate an icing cloud containing Super-cooled Large Droplets (SLD) in the Icing Research Tunnel (IRT) at the NASA Glenn Research Center. A spray sequencing method was used to reproduce the bimodal droplet distribution normally found in SLD clouds in nature. The spray sequencing process consisted of setting two different spray bar manifold pressures, each representing separate drop size and Liquid Water Content (LWC) conditions, and then spraying a target airfoil using several different sequence patterns. The spray bar conditions used were selected to produce the same freezing fraction conditions at the stagnation line on the airfoil in order to maintain thermal continuity from one spray exposure to the next. Results of the experiments include ice shape tracings and photographs of the various exposures. Ice shape tracings are then compared to identify differences in ice shape features resulting from the various sequencing patterns.