The range of applicability of classical panel methods for incompressible
flows has often been extended to address compressible, subsonic flows by
"compressibility corrections", where the solution for an incompressible flow
about a body (or a modified shape of body) is used to predict the
compressible results about the original shape - the classical approach is to
use the Prandtl-Glauert/Göthert approach. However, this has met with mixed
success and requires care in its correct application. This has led other
methods to use corrections to the incompressible solution for the pressures
about the body (e.g. the von Kármán-Tsien compressibility correction).
Recent work at Flow Solutions has obtained a new formulation of the
compressibility correction that yields accurate answers up to the onset
of transonic flow and does not suffer from the problems seen with other
Presented here is a comparison of NEWPAN with experimental results, for
a wing plus fuselage test case in subsonic compressible flow. This testcase
was reported by W.Schneider at DLR , and features a wing of Aspect Ratio
6 with a 9% thick RAE101 profile. Experimentally it was tested at Mach numbers
from 0.5 to 0.8.
NEWPAN results with Prandtl-Glauert compressibility correction show excellent
agreement with experiment - aside from the highest Mach number/incidence
combinations, where the experimental data shows that a shock has started to
form. Cpcrit, the value of pressure coefficient necessary to achieve local
sonic flow, is plotted for the high Mach number cases. Where the sectional
pressure distribution crosses the Cpcrit line we would expect poorer
experimental comparisons due to the presence of locally sonic flow.
 W.Schneider, Druckverteilungsmessungen an Pfeilflügel-Rumpf-Anordnungen bei hohen Unterschall-Machzahlen,
Teil II: Flügel mit dickem Rumpf, DFVLR, Aerodynamische Versuchsanstalt Göttingen, interner Bericht 70 A 40, 1970
Use the interactive NEWPAN results browser to view the comparison with
To change the spanwise section displayed in the graph plot,
left mouse click on a white wing section in the 3D view above.