15 In-flight Icing: Modeling, Prediction, and Uncertainty
473
addition model based on bisection of angle between adjacent panels. Blackmore and
Lozowski [54] and Blackmore et al. [55] introduced an icing model used to describe
spongy atmospheric icing, and a dendritic-growth layer was assumed to correlate the
microscopic ice growth with macroscopic mass/energy conservation. Kong and Lui
[56] introduced a method for predicting supercooled icing in which influences of
the flow velocity on ice growth were taken into account.
Currently respective prediction codes for ice accretion also exist, namely
LEWICE [57], ONERA [58], FENSAP-ICE [59], and PoliMIce [60] and others.
These codes are built as modelling frameworks in which aerodynamic solvers are
coupled to ice formation models. In addition, they solve energy and mass balances
in order to determine the amount of ice formed and its shape. Further details can be
found in Sect. 15.3.
15.2.6 Ice Accretion and Performances
The accumulation of ice in-flight on aircraft surfaces modifies the interactions
between the aircraft and the environment. For instance, ice accreted shapes change
the shape of the wing aerodynamic profiles and this influences the performance of
the aircraft. It is highlighted that ice accretion is always unwanted and it hinders its
operational performance and the safety. For this reason, aircraft must be effectively
protected against ice. This section will present an overview of the most important
effects of ice accretion on the performance and safety of the aircraft.
15.2.6.1 Fixed-Wing Icing Environment
Ice accumulates in all the aircraft surfaces that are exposed to the environment.
The study of the impact on the performance is crucial because of the number of
accidents which were proven to be caused by ice accretion in both ice protected and
unprotected aircraft [61]. The understanding of these effects supports the design of
better systems and the elaboration of more robust certification procedures.
The accumulation of ice, regardless of the severity, modifies the shape of
aerodynamic surfaces such as wings and stabilizers and therefore alters the flow
and the pressure distribution [62]. In the case of the aircraft wings it leads to a
dramatic increase in drag and a drop in lift. In addition, the maximum lift coefficient
decreases as well as the maximum angle of attack. The stall speed is also increased.
The change in shape experienced by the stabilizers, particularly the horizontal
stabilizer, decreases its critical angle of attack and reduces the amount of negative
lift it generates. This decreases its ability to compensate the nose-down pitching
moment which can undermine the aircraft stability [5]. Aircraft control surfaces
are located at the wings and stabilizers. The changes in the pressure distribution
over their surface alter the hinge moment and consequently the force required to
operate them. Furthermore, with the increased profile drag from ice accretion, a
473
addition model based on bisection of angle between adjacent panels. Blackmore and
Lozowski [54] and Blackmore et al. [55] introduced an icing model used to describe
spongy atmospheric icing, and a dendritic-growth layer was assumed to correlate the
microscopic ice growth with macroscopic mass/energy conservation. Kong and Lui
[56] introduced a method for predicting supercooled icing in which influences of
the flow velocity on ice growth were taken into account.
Currently respective prediction codes for ice accretion also exist, namely
LEWICE [57], ONERA [58], FENSAP-ICE [59], and PoliMIce [60] and others.
These codes are built as modelling frameworks in which aerodynamic solvers are
coupled to ice formation models. In addition, they solve energy and mass balances
in order to determine the amount of ice formed and its shape. Further details can be
found in Sect. 15.3.
15.2.6 Ice Accretion and Performances
The accumulation of ice in-flight on aircraft surfaces modifies the interactions
between the aircraft and the environment. For instance, ice accreted shapes change
the shape of the wing aerodynamic profiles and this influences the performance of
the aircraft. It is highlighted that ice accretion is always unwanted and it hinders its
operational performance and the safety. For this reason, aircraft must be effectively
protected against ice. This section will present an overview of the most important
effects of ice accretion on the performance and safety of the aircraft.
15.2.6.1 Fixed-Wing Icing Environment
Ice accumulates in all the aircraft surfaces that are exposed to the environment.
The study of the impact on the performance is crucial because of the number of
accidents which were proven to be caused by ice accretion in both ice protected and
unprotected aircraft [61]. The understanding of these effects supports the design of
better systems and the elaboration of more robust certification procedures.
The accumulation of ice, regardless of the severity, modifies the shape of
aerodynamic surfaces such as wings and stabilizers and therefore alters the flow
and the pressure distribution [62]. In the case of the aircraft wings it leads to a
dramatic increase in drag and a drop in lift. In addition, the maximum lift coefficient
decreases as well as the maximum angle of attack. The stall speed is also increased.
The change in shape experienced by the stabilizers, particularly the horizontal
stabilizer, decreases its critical angle of attack and reduces the amount of negative
lift it generates. This decreases its ability to compensate the nose-down pitching
moment which can undermine the aircraft stability [5]. Aircraft control surfaces
are located at the wings and stabilizers. The changes in the pressure distribution
over their surface alter the hinge moment and consequently the force required to
operate them. Furthermore, with the increased profile drag from ice accretion, a