Cw. Hustad et al., A NUMERICAL INVESTIGATION OF AEROFOIL BOUNDARY-LAYER MANIPULATOR PROFILE FOR CRUISE-FLIGHT CONDITIONS, Applied scientific research, 54(4), 1995, pp. 267-280
A computational study has been conducted to determine the variation of
device drag with profile shape and angle of attack for aerofoil bound
ary-layer manipulators (LEBUs) operating at high subsonic Mach numbers
. Calculations have been made at a free-stream Mach number of 0.80 for
both symmetrical and asymmetrical NACA-00xx and 44xx series devices i
ncluding an inverted cambered NACA-4409 profile. The LEBUs considered
were located in a turbulent boundary-layer at a mid-chord height h equ
ivalent to 0.67 delta from the wall. The present investigations sought
to confirm suggestions based upon experimental observations that ther
e may be some advantage in replacing a symmetrical device by an invert
ed asymmetrical profile form. The computations were performed using an
unstructured adaptive-mesh 3D Navier-Stokes code incorporating a Lam
and Bremhorst low-Reynolds number two-equation k - epsilon turbulence
model. The calculated flow field around a NACA-0009 aerofoil at zero a
ngle of attack was initially verified against experimental interferome
tric data. The calculated device drag coefficient at zero incidence wa
s 0.026 for the NACA-0009, similar to that measured in experiments. Ho
wever predicted drag for an inverted NACA-4409 was 0.085, this being c
onsiderably higher than anticipated. The results suggested that a slig
htly positive angle of attack may help minimise device drag but neithe
r profile is appropriate for use in transonic conditions. Improved res
ults may be obtained from inverted flat-topped profiles designed to mi
nimise losses associated with localised shocks.