M.Sc Thesis


M.Sc StudentDanny Abramov
SubjectPassive Prevention of Icing on the Rear Element of a
Two-Element Airfoil
DepartmentDepartment of Aerospace Engineering
Supervisors Professor Iosilevskii Gil
Mr. Michael Shafshalovich
Full Thesis textFull thesis text - English Version


Abstract

Today, two-element high-lift wings are the mainstream of UAV design activities, at least at IAI. They come to support the concept of high-lift loitering flight of operational (high drag) configurations. Two-element airfoils are variable camber, mission-adaptive arrangements that provide build-in options of take-off / landing flaps, ailerons, airbrake and decambering at high-speed flight. They improve loitering flight performance of a UAV under normal operating conditions. The challenge is in making these wings suitable for all-weather operations, and, in particular, suitable for operation in icing conditions. For a conventional wing, all weather operational capability requires installation of a deicing system at the leading edge - the most vulnerable part of the wing as far as maximum lift and drag characteristics are concerned. The problem is that two-element wings have two leading edges.


Installation of a deicing system on the leading edge of the rear element of a two-element wing is costly, carries large weight penalty and required maintenance. At the same time, ice accretion on the leading edge of the rear element is intolerable - since the rear element doubles as a control surface, restriction of its mechanical travel or reduction in its aerodynamic efficiency may lead to a loss of control. Passive prevention of ice accretion on the rear segment of two-element airfoil is a main objective of the present study. It is shown that small modification of the airfoil contours can exploit the difference in inertial properties of water droplets and air, and prevent them from hitting the leading edge of the rear element. With no water droplets there is no ice accretion.