F. Saeed et al., HYBRID AIRFOIL DESIGN METHOD TO SIMULATE FULL-SCALE ICE ACCRETION THROUGHOUT A GIVEN ALPHA-RANGE, Journal of aircraft, 35(2), 1998, pp. 233-239
A design procedure is presented for hybrid airfoils with full-scale le
ading edges and redesigned aft sections that exhibit full-scale airfoi
l water droplet-impingement characteristics throughout a given angle o
f attack or a range, The design procedure is an extension of a previou
sly published method in that it not only allows for subcritical and vi
scous-flow analysis in the design but is also capable of off-design dr
oplet-impingement simulation through the use of a flap system, The lim
itations of the nap-system-based design for simulating both on-and off
-design full-scale droplet-impingement characteristics and surface-vel
ocity distribution are discussed with the help of specific design exam
ples, In particular, this paper presents the design of two hybrid airf
oils at two different angles of attack, such that they simulate both t
he full-scale velocity distribution as well as droplet-impingement cha
racteristics at the respective design angles of attack, Both of the hy
brid airfoils are half-scale airfoil models with the nose section matc
hing the full-scale coordinates of the Learjet 305 airfoil back to 5%
chord on the upper surface and 20% chord on the lower surface, The eff
ect of nap deflection and droplet size on droplet-impingement characte
ristics is also presented to highlight the important limitations of th
e present method both on-and off-design. This paper also discusses imp
ortant compromises that must be made to achieve full-scale ice accreti
on simulation throughout a desired a range and suggests alternatives s
uch as applying a multipoint design approach.