Experimental assessment of rigid surface collision effects on suspended ice particles

In glaciated icing conditions, when the aircraft impacts ice particles in the cloud, the ice particles may rebound, fragment or stick to the aircraft surface, further affecting the ice accretion process. However, the fragmentation mechanism particularly near the minor fragmentation zone is complex and not clear. Here, two particle diameter levels (1.24 mm and 1.56 mm) and three impact velocity levels (7 m/s, 10 m/s, 16 m/s) were set to perform ice particle impact experiment on the self-developed high-speed ice particle impact experimental setup. A Kalman filter tracking algorithm and a projective stereological method were improved and used to track and calculate the volume of the fragments, respectively. According to the statistical analysis of the experimental results, it was found that the impact character number ξ is a valid dimensionless number for measuring the degree of fragmentation. The results of the fragment volume calculation were then verified and it was found that the addition of the semi-ellipsoid shape improves the accuracy of the calculation, reducing the mean relative error by more than 9 %. Finally, a correlation between the impact character number ξ and the distribution exponent Ψ̂ was obtained. Combined with the fragmentation mode probability model and the estimate correlation for the upper cut-off position, a possible model for the fragment volume distribution near the minor fragmentation zone was constructed. Due to the existence of scale invariance and the dimensionless number in this model, it may be applicable to a higher range of ξ.