An Investigation On The Icing Mechanics Of Supercooled Large Droplets Impacted On Dynamic Phenomena

On Oct.31, 1994, an accident involving an ATR72-212 series airplane, in which all passengers and crew are died, occurred in Roselawn, Indiana, US. This disaster investigation led to a conclusion that this aeroplane fulfilled the airworthiness directive, but involved in typical icing circumstance beyond the reach of the FAR 25, Appendix C, which induced icing anomaly. The supercooled large droplet (SLD) has a diameter more than 50μm with a complicated icing mechanism, which forms a significant flight safety risk. Since there are some defects on the dynamic models for icing simulation, the paper concentrates on discussing the specific dynamic phenomenon of SLD, summarizes the multifactor-effected breakup (MEB) model and the large droplet slipping (LDS) model, certifies its valid effect on SLD icing simulation with reformed ice accreting arithmetics. The paper indicates the MEB and LDS model can both improve SLD icing simulation positively. Based on the two models, the paper also analyzes the dynamic effects on droplet-colleting-rate and SLD icing characteristic of changing diameter-distribution, impinging-characteristic. Moreover, by simulating the ice sharps of NACA0012 at different AOAs and LWCs with new models, the paper reflects the complication of SLD-icing and its sensibility to flow conditions.