Experimental Icing Tunnel Testing of a Large-Scale Propeller

Within the project “Propeller Ice Shed Measurement”, which received funding from the Austrian Research Promotion Agency, two experimental test campaigns were carried out in the Rail Tec Arsenal Icing Wind Tunnel using two different large-scale propellers, which both were equipped with an electrothermal ice protection system. In the first test campaign, a commercial general aviation propeller with a diameter of 2.032 m was used. For the second test campaign, a bespoke propeller with a diameter of 2.2 m was developed, based on NACA series airfoils. The main aim of the project was to generate a validation database for ice shapes and to investigate the ice shedding behavior on large propellers with an aerodynamic performance representative of transport category or large general aviation aircraft. Furthermore, the impact energy of the shed ice particles was investigated. In total, 45 icing test runs in Appendix C and Appendix O Freezing Drizzle conditions were performed (28 unprotected and 17 with an active IPS). The ice shapes along the entire blade radius were documented using high-resolution 3D scanning, with a total of 28 shapes being recorded. Selected cases from the second test campaign are presented. During the two test campaigns more than 250 ice shed events occurred, which were caused either naturally by the centrifugal load or by the activation of the ice protection system. The ice shedding characteristics were investigated, including estimations on the ice density and ice adhesion strength. The shed ice particles were tracked with a stereo camera setup to investigate their trajectories and velocities and captured in foam blocks oriented around the propeller plane for further evaluation of their volume, mass and density in order to derive their kinetic energy. An initial performance evaluation of the PrISM propeller under different icing conditions was also performed.