Experimental measurement of ice accretion due to mixed-phase icing clouds

The ingestion of ice crystals can result in engine icing incidents. These ice crystals are ingested into the engine, become partially melted and freeze on low pressure stators and casing. This paper introduces a series of mixed-icing experiments conducted inside the Pennsylvania State University Icing Wind Tunnel (PSU-IWT). The objective was to investigate how surface temperature and percentage melting of the icing cloud affect the ice accretion rate. An icing cloud was sprayed into the wind tunnel providing fully frozen water droplets. The fully glaciated cloud was partially melted using hot air ingestion. A NACA 0012 airfoil, instrumented with two thermocouples, was used as the test article. The temperature at the leading edge was maintained using internal temperature controlled airflow. The experimental results shows how variations from fully frozen to fully partially melted clouds affect the ice accretion thickness. Within the range of test conditions discussed in the paper, the ice accretion decreases with increases of the temperature of the ingested air. The increment of surface temperature reduces ice accretion until the surface temperature reached-10 °C. The erosion effect in PSU-IWT is less significant compared with results from similar test facilities. The capability of PSU-IWT in mixed-phase icing is verified and preliminary test results are shown.