Quantitative Comparison of Ice Accretion Shapes on Airfoils

The need to compare quantitatively ice accretions that form on aircraft during e ight in icing conditions has recently expanded from a research-oriented activity to more general applications. For example, verie cation of the calibration of ground-test facilities is often performed by comparing ice shapes produced at a specie c icing condition. Becauseicing tests in ground facilitiesare important in the aircraft certie cation process, concernsabout the subjectivity and consistency of these ice shape comparisons have increased. The ice accretion comparison method presented uses geometric features as well as several parameters extracted from a P-Fourier descriptor of theiceaccretionproe letodevelopasingleparameterthatcanbeused torankhowwelltwoiceshapescompare.The results of this automated method were found to be consistent with comparisons of ice accretions made visually and based on percent differences of geometric characteristics. Also, for comparisons of ice shapes having a calculated comparison parameter less than 0.075 (7.5%), the drag coefe cient of the iced airfoils differs by less than 10%. Higher values of the comparison parameter produce greater visual differences in the ice accretions and larger variations in the drag coefe cient.