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Droplet deformation and breakup is an important issue that involved in the aircraft and engine icing field especially in the case of the Supercooled Large Droplets (SLD). In this paper, the modes of SLD breakup were discussed in detail based upon the classical theories of droplet breakup and typical icing conditions. It was found that the breakup modes involved in SLD are mainly vibration breakup, bag-type breakup, multimode breakup and shear breakup. A breakup model composed of the typical SLD breakup types was proposed.

Aircraft icing causes a great threaten to flight safety. With the development of anti-icing or de-icing systems for aircraft, some attention has been paid on coating strategies for an efficient way to prevent water remaining on the surface. By application of hydrophobic or super-hydrophobic coatings, characterized by low surface adhesion, shedding of liquid from the surface can be enhanced. The motivation behind this work is to identify the way that wettability affects the motion of runback water, and establish an empirical formula of critical departure diameter. The surface property is characterized by the equilibrium contact angle and the hysteresis angle. The relationship between the air speed and the droplet shedding diameter is studied, corresponding to different surfaces.

Euler method was used in calculating the gas-liquid two-phase flow field. With the help of the user defined function (UDF) in FLUENT software, the water local collection efficiency and ice accretion on three dimensional wings were solved. The flow motion of runback water was divided along the chordwise and spanwise direction respectively during the computation procedure and the classical Messinger model was modified to be applicable to simulate three dimensional ice accretion. The analysis about three dimensional mass and heat transfer was also performed according to the modified Messinger model. Based on the traditional method of calculating heat transfer coefficient on two dimensional surfaces, an improved method was applied to compute the heat transfer coefficient on three dimensional wings. The direction of ice accretion was defined to be normal to the wing surface. The comparative results showed that the three dimensional ice accretion code developed in this paper was effective.

Electro-thermal deicing process was an unsteady heat transfer process including phase change. Based on the investigation of such a process, a code was developed to numerically simulate electro-thermal deicing process. Phase change was performed by an enthalpy method. A staircase approach was used to describe the variable ice thicknesses along the icing surface. The control volume method was adopted to discretize the governing equations. Tri-diagonal matrix method, alternating direction implicit method and block-correction technique were used to solve the discrete equations. Results of temperature distribution in this investigation were compared with experimental results of previous study. Their good agreements indicate the validity of our simulation. The effects of icing conditions, such as ambient temperature, liquid water content (LWC) and flight velocity, etc., were analyzed through a case. Some useful conclusions were achieved.