22-10-2012, 05:12 PM
Design and Testing of a Blended Wing Body With Boundary Layer Ingestion Nacelles at High Reynolds Numbers
ABSTRACT
A knowledge-based aerodynamic design method coupled with an unstructured grid Navier-Stokes flow solver was used
to improve the propulsion/airframe integration for a BlendedWing Body with boundary-layer ingestion nacelles. A new zonal
design capability was used that significantly reduced the time required to achieve a successful design for each nacelle and the
elevon between them. A wind tunnel model was built with interchangeable parts reflecting the baseline and redesigned
configurations and tested in the National Transonic Facility (NTF). Most of the testing was done at the cruise design conditions
(Mach number = 0.85, Reynolds number = 75 million). In general, the predicted improvements in forces and moments as well
as the changes in wing pressures between the baseline and redesign were confirmed by the wind tunnel results. The
effectiveness of elevons between the nacelles was also predicted surprisingly well considering the crudeness in the modeling
of the control surfaces in the flow code. A novel flow visualization technique involving pressure sensitive paint in the
cryogenic nitrogen environment used in high-Reynolds number testing in the NTF was also investigated.