Ice Accretion Roughness Variations on a Hybrid CRM65-Midspan Wing Model

Ice accretion roughness measurements were performed in the Icing Research Tunnel (IRT) at NASA Glenn Research Center for the Hybrid CRM65-Midspan model in a range of icing conditions. The Hybrid CRM65-Midspan model was chosen for this investigation because 1) the model exhibits high sweep relative to models previously explored in the roughness investigations, 2) the model has leading edge characteristics similar to wing shapes currently used in mid-size commercial airliners, and 3) the sweep and thickness ratios relate better to hybrid lifting body designs for N+2 and N+3 vehicles than other models available. The investigation consisted of multiple sets of tests which focused on 1) 0 deg-angle of attack cases replicating the conditions employed by Anderson et al. (1998) using both Appendix C and Supercooled Large Drop (SLD) cloud conditions, 2) cases based on the Max Scallop case by Broeren et al. (2016) and a “High Temperature” case with cloud properties similar to the Max Scallop case. Additional tests were performed 1) based on the Max Scallop case with variations in freestream static temperature and 2) using test section speeds near 10,000-ft hold flight conditions. The point clouds were characterized using the approach of McClain and Kreeger (2013) for the ice roughness variations and using the approach of McClain (2016) for the mean ice thickness variations. The resulting roughness and mean thickness variations generally follow the temporal scaling previously identified using airfoil models without sweep, but the collapse of the time progression profiles is not as tight as found for past measurements on models without sweep. Computational fluid dynamics (CFD) and LEWICE3D predictions reported by Yadlin et al. (2018) were used to compare the measured spatial roughness variations to predictions using the roughness correlations developed by McClain et al. (2021) for the Max Scallop cases.