468
B. Arizmendi et al.
behavior of droplets impinging in super-hydrophobic tilted surfaces [26]. It was
discovered that under certain surface angle and velocity, the droplets rebounded after
impacting. Furthermore, it was found that the implementation of super-hydrophobic
coatings over the surface of the wings could reduce the rate of ice accretion [27].
However, it was acknowledged that the use of these types of coatings required
additional ice protection means due to the physical degradation of the surface
itself. Further research from Antonini and collaborators found out that the use of
super-hydrophobic coatings could decrease the energy consumption of the fully
evaporative thermal anti-ice protection systems [28]. From a review of literature it is
concluded that the use of coatings could support the performance of ice protection
systems by decreasing the amount of icing over critical surfaces.
On a related note, the adhesion of ice to solid surfaces has also been investigated
over more than 50 years which highlights the relevance of the field [29]. This
research has been mainly conducted experimentally, to understand the mechanisms
of ice adhesion. Over the so-called icephobic materials, the ice accreted presents
low adhesion and therefore, if the layer of ice is large enough it detaches from
the surface and sheds. Research intended to link “icephobia” to wettability of the
surface. However, the link is not clear since some contemporaneous authors claim it
is independent [30] and other authors relate the two properties [31].
15.2.4.2 Ice Shedding
Ice shedding consists of the detachment of the accreted ice on a surface of, e.g.,
aircraft, rotating propellers, and helicopters. The study of the trajectories of large
ice particles is critical because those can impact over distant surfaces and cause
damages. With regards to the ice accreted over aircraft leading edge, the shed
particles can be ingested by the engines aft and cause damages. The stresses on
the accreted ice layer that cause the shedding are originated by inertia forces,
aerodynamic pressure forces, thermal stresses, and also flexing of the aircraft wings.
The numerical studies of ice shedding conducted by Scavuzzo concluded that there
is a critical value of the aircraft Mach number to which the aerodynamic forces are
significant enough to cause shedding in typical aeronautic applications [32].
Ice shedding in aircraft was studied by means of numerical models, for instance,
Zhang et al. developed a Finite Element Analysis (FEA) model to study ice
mechanics by means of a fracture mechanics framework [33]. It was concluded that
the shape of the ice strongly influences the shedding onset. In addition, Papadakis
et al. performed a complete study to model the trajectories of the ice shed by means
of a multi-body dynamic solver and CFD [34]. Moreover, included experimental
aerodynamic characteristics of the ice particles into the numerical model. The
authors acknowledged the randomness of the process. Consequently, they performed
a Monte Carlo approach to quantify the probability of the icing trajectories and to
find the most likely ones. The numerical modeling of the trajectories of ice particles
shed can help the design of de-icing systems to ensure those particles do not impact
on critical components or surfaces.
B. Arizmendi et al.
behavior of droplets impinging in super-hydrophobic tilted surfaces [26]. It was
discovered that under certain surface angle and velocity, the droplets rebounded after
impacting. Furthermore, it was found that the implementation of super-hydrophobic
coatings over the surface of the wings could reduce the rate of ice accretion [27].
However, it was acknowledged that the use of these types of coatings required
additional ice protection means due to the physical degradation of the surface
itself. Further research from Antonini and collaborators found out that the use of
super-hydrophobic coatings could decrease the energy consumption of the fully
evaporative thermal anti-ice protection systems [28]. From a review of literature it is
concluded that the use of coatings could support the performance of ice protection
systems by decreasing the amount of icing over critical surfaces.
On a related note, the adhesion of ice to solid surfaces has also been investigated
over more than 50 years which highlights the relevance of the field [29]. This
research has been mainly conducted experimentally, to understand the mechanisms
of ice adhesion. Over the so-called icephobic materials, the ice accreted presents
low adhesion and therefore, if the layer of ice is large enough it detaches from
the surface and sheds. Research intended to link “icephobia” to wettability of the
surface. However, the link is not clear since some contemporaneous authors claim it
is independent [30] and other authors relate the two properties [31].
15.2.4.2 Ice Shedding
Ice shedding consists of the detachment of the accreted ice on a surface of, e.g.,
aircraft, rotating propellers, and helicopters. The study of the trajectories of large
ice particles is critical because those can impact over distant surfaces and cause
damages. With regards to the ice accreted over aircraft leading edge, the shed
particles can be ingested by the engines aft and cause damages. The stresses on
the accreted ice layer that cause the shedding are originated by inertia forces,
aerodynamic pressure forces, thermal stresses, and also flexing of the aircraft wings.
The numerical studies of ice shedding conducted by Scavuzzo concluded that there
is a critical value of the aircraft Mach number to which the aerodynamic forces are
significant enough to cause shedding in typical aeronautic applications [32].
Ice shedding in aircraft was studied by means of numerical models, for instance,
Zhang et al. developed a Finite Element Analysis (FEA) model to study ice
mechanics by means of a fracture mechanics framework [33]. It was concluded that
the shape of the ice strongly influences the shedding onset. In addition, Papadakis
et al. performed a complete study to model the trajectories of the ice shed by means
of a multi-body dynamic solver and CFD [34]. Moreover, included experimental
aerodynamic characteristics of the ice particles into the numerical model. The
authors acknowledged the randomness of the process. Consequently, they performed
a Monte Carlo approach to quantify the probability of the icing trajectories and to
find the most likely ones. The numerical modeling of the trajectories of ice particles
shed can help the design of de-icing systems to ensure those particles do not impact
on critical components or surfaces.