Abstract
<div class="section abstract"><div class="htmlview paragraph">Numerical investigation of airflow at a transonic speed over the wing of the NASA
high-lift Common Research Model (CRM) with and without a conformal vortex
generator (CVG), placed on the airfoil suction side has been performed. The
objective of the investigation was to assess the impact of CVG on the wing’s
lift to drag (L/D) ratio and tip vortices. The wing has aspect and taper ratios
of respectively 9, and 0.275, and a leading-edge sweep angle of 37.24 degrees.
The root and tip chords were respectively 11.81m and 2.73 m with an approximate
mean chord of 6.62 m. The angle of attack was 2.5 degrees. The CVG was distorted
V-shaped with a base distance of approximately 4.8 cm, a depth of 8.8 cm, and a
tip-to root angle of approximately 30.2<sup>0</sup>. The CVG is on both sides of
the tape pointing in opposite directions. The tape is 2 mm thick, 83 cm wide,
spanning the entire length of the wing surface. The leading edge of the CVG tape
starts at 60% of the chord from the leading edge of the airfoil. The airspeed
was 251 m/sec.at 40,000 ft elevation which corresponds to a Reynolds number
based on the mean chord of approximately 3.5x10<sup>7</sup>. Properties of the
air at this elevation were used for the simulation. The Mach number was 0.85.
These values correspond to the typical cruise speed of commercial airlines. The
grid size for the baseline airfoil after grid-dependency test was 8.62 million
and the one with CVG was about 10 million. Reynolds-Averaged Navier Stokes
(RANS) equations along with K-ɷ SST turbulence model with all y<sup>+</sup> wall
treatment were used. Results have shown a nearly 6% improvement in L/D ratio and
reduced tip vortices with CVG in place<b>.</b></div></div>