In this paper, an analysis in computational uid dynamics (CFD) is presented on a
helicopter scale model with focus on the main-rotor blades.The helicopter model
is encapsulated in a background region and the ow eld is solved using Star CCM+.
A surface and volume mesh continuum was generated that contained approximately
seven million polyhedral cells, where the Finite Volume Method (FVM) was chosen
as a discretization technique. Each blade was assigned to an overset region
making it possible to rotate and add a cyclic pitch motion. Boundary information
was exchanged between the overset and background mesh using a weighted
interpolation method between cells. An implicit unsteady ow solver, with an
ideal gas and a SST (Mentar) K-Omega turbulence model were used. Hover and
forward cases were examined. Forward ight cases were done by changing the rotor
shaft angle of attacks and the collective pitch angle 0 at the helicopter
freestream Mach number of M = 0:128, without the inclusion of a cyclic pitch
motion. An additional ight case with cyclic pitch motion was examined at s = 0
and = 0. Each simulation took roughly 48 hours with a total of 96 parallel cores
to compute. Experimental data were taken from an existing NASA report for
comparison of the results. Hover ight coincided well with the wind tunnel data.
The forward ight cases (with no cyclic motion) produced lift matching the
experimental data, but had diculties in producing a forward thrust. Moments in
roll and pitch started to emerge. By adding a cyclic pitch successfully removed
the pitch and roll moments. In conclusion this shows that applying overset
meshes as a way to analyze the main-rotor blades using CFD does work. Adding a
cyclic pitch motion at 0 = 5 and s = 0 successfully removed the roll and
pitching moment from the results.
Author: Rodriguez, Christian Source: KTH
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