The computer software LEWICE is an analytical ice
accretion package that simulates the thermodynamics of
the freezing process occurring when supercooled droplets impinge on a
body. LEWICE was developed at then NASA Lewis , now NASA Glenn, its
development continues to be supported by the Icing Branch at NASA Glenn.
LEWICE applies a time-stepping procedure to "grow" an ice accretion.
Initially a flow field is calculated, then particle trajectories and
impingements are calculated, then ice growth is calculated, the
is then modified and the process repeated until the length of the icing
encounter is reached. LEWICE is used to determine icing impingement
limits, failed deicer ice shapes, unprotected surfaces ice shapes,
thermal requirements of thermal ice protection systems. LEWICE is a
valuable tool when used be experienced users and combined with such
validation techniques as icing wind tunnel testing and flight testing.
The above ice shape was
predicted using LEWICE for the
unprotected horizontal stabilizer of Piper
Cherokee 6 (PA32-260). The aircraft is holding at the unrealistic
speed, for a PA32, of 130 kts. Such an accumulation would result in a
substantial increase in drag and reduction in lift for this surface.
The horn on the upper surface act much like a full span spoiler and
could produce such undesired phenomena as an elevator snatch.