15 In-flight Icing: Modeling, Prediction, and Uncertainty
475
deployed. The authors concluded that further considerations need to be included
into the model. Moreover, when ice accumulates in probes and in sensors, the
readings provided can be altered and this can provide misleading information about
the current flying situation. For instance, if ice accumulates in the outside air
temperature sensor, the reading will provide the temperature of the ice accreted
rather than the actual air temperature. Some other sensors are not designed to work
in icing conditions and the reading can be misleading and hinder the assessment of
the operating condition [11].
15.2.6.2 Rotating-Wing Icing Environment
Rotorcraft flight in icing environments is indeed a notoriously challenging phenomenon in which the formation of the ice is inherently unpredictable. This, coupled
with the complex multi-body rotorcraft aerodynamics, makes it infamously difficult
to prognosticate, not to mention the extent of time required to do so. If such
a scenario occurs, the presence of ice on the blades of the main rotor can lead
to severely damaging consequences to the helicopters’ performance capabilities,
becoming a serious threat to flight safety [64] and the cause of several aircraft
icing accidents [4]. It can prompt drastic alterations to the geometry and increase
the surface roughness thus, resulting in the increase of drag, reduction of lift and
premature onset stall. These aerodynamic changes invariably have implications
on the helicopter stability, flight condition, power and torque characteristics, and
component loading [65, 66]. The buildup of ice on the rotor blades can also alter the
trim conditions due to disturbing the blades balanced weight as well as modifying
the inertia and aero-elastic properties of the blades themselves [60].
15.3 Modeling Ice Accretion
This section will discuss the various numerical methods used to compute an inflight ice accretion simulation described in Sect. 15.2. It will briefly describe the
development of the methods in order to obtain an accurate solution. An in-flight
ice accretion computation is conventionally performed using a multi-stage process,
including a feedback loop to iteratively update the iced geometry as shown [67]:
• Flow Solver: Used to determine the flow field around the aerodynamic body.
• Droplet Solver: Required for computing the water droplet trajectories for the
local and global collection efficiency.
• Ice Accretion Solver: Necessary to predict the final ice shape around the
aerodynamic body.
• Mesh Morphing: Implemented for updating the newly accreted iced geometry
into the flow solver.
475
deployed. The authors concluded that further considerations need to be included
into the model. Moreover, when ice accumulates in probes and in sensors, the
readings provided can be altered and this can provide misleading information about
the current flying situation. For instance, if ice accumulates in the outside air
temperature sensor, the reading will provide the temperature of the ice accreted
rather than the actual air temperature. Some other sensors are not designed to work
in icing conditions and the reading can be misleading and hinder the assessment of
the operating condition [11].
15.2.6.2 Rotating-Wing Icing Environment
Rotorcraft flight in icing environments is indeed a notoriously challenging phenomenon in which the formation of the ice is inherently unpredictable. This, coupled
with the complex multi-body rotorcraft aerodynamics, makes it infamously difficult
to prognosticate, not to mention the extent of time required to do so. If such
a scenario occurs, the presence of ice on the blades of the main rotor can lead
to severely damaging consequences to the helicopters’ performance capabilities,
becoming a serious threat to flight safety [64] and the cause of several aircraft
icing accidents [4]. It can prompt drastic alterations to the geometry and increase
the surface roughness thus, resulting in the increase of drag, reduction of lift and
premature onset stall. These aerodynamic changes invariably have implications
on the helicopter stability, flight condition, power and torque characteristics, and
component loading [65, 66]. The buildup of ice on the rotor blades can also alter the
trim conditions due to disturbing the blades balanced weight as well as modifying
the inertia and aero-elastic properties of the blades themselves [60].
15.3 Modeling Ice Accretion
This section will discuss the various numerical methods used to compute an inflight ice accretion simulation described in Sect. 15.2. It will briefly describe the
development of the methods in order to obtain an accurate solution. An in-flight
ice accretion computation is conventionally performed using a multi-stage process,
including a feedback loop to iteratively update the iced geometry as shown [67]:
• Flow Solver: Used to determine the flow field around the aerodynamic body.
• Droplet Solver: Required for computing the water droplet trajectories for the
local and global collection efficiency.
• Ice Accretion Solver: Necessary to predict the final ice shape around the
aerodynamic body.
• Mesh Morphing: Implemented for updating the newly accreted iced geometry
into the flow solver.