| SLD (Supercooled Large droplets) is the supercooled water droplets with diameter larger than 100 microns, and is not included in the current airworthiness standard FAR25 Appendix C icing envelope. The effect of SLD icing is very different from those common small-diameter water droplets, one of the typical factor is the dynamics effect of large droplets, such as the breakup and splashing phenomena upon impacting the wing . Compared to those common small-diameter water droplets, the dynamics of SLD significantly change the ice shape, and the ice shape is contributed by the combined result of the dynamic effect (breakup, impact and splash, flow)and the thermodynamic effect. The influence of these aspects to the ice shape is also different: such as effect of SLD breakup can result in reduction on the overall ice volume, while effect of SLD splash can result in reduction on the ice volume near the leading edge. The paper demonstrates the reasonability of the simulating system by icing simulation on droplets with small diameter, then points out the inaccuracy of icing simulation on SLD as a result of ignorance of the dynamic effect. According to the analysis of some key parameters in the model, this paper analyzes the movement of water droplets in the vicinity of the wing, and simulates the SLD ice accretion process in combination of the splash effect. The simulation results match well with the experimental results from ice wind-tunnel which reveals that there are some deficiencies in the breakup model though it is reasonable on certain degrees, so the mechanism of SLD breakup need to be studied and the new model of breakup need to be improved. |
