Aluminum Sample Characterization on the NRC AIWT Ice Adhesion Spin Rig

This paper presents the adhesion strength of ice on sanded and machine-finished aluminum test coupons as measured using the National Research Council of Canada (NRC) Altitude Icing Wind Tunnel (AIWT) spin rig. This rig is used to evaluate commercial and internally-developed coatings for low-adhesion properties, and the performance of ice on aluminum is required as a baseline to compare the coatings against. The tests are performed over a range of aerodynamic and icing cloud conditions, including variations in static air temperature and exposure time (and therefore accumulated ice mass). The data analysis includes an evaluation of the uncertainty in the results based on the measured ice mass repeatability and the measured shear stress repeatability. The results show the adhesive shear stress of ice, generated with a 20 μm icing cloud at a true airspeed of 80 m/s and a static air temperature of -20°C to create rime ice conditions, is 682 kPa (±13%) for aluminum coupons with a sanded finish and 579 kPa (±16%) for aluminum coupons with a machined finish. The results are comparable to those found in literature for aluminum samples tested using centrifugal methods. There was no observed trend in the adhesive shear stress with variations in temperature or ice mass, within the range of conditions tested.