Experimental and numerical investigations are performed in an effort to elucidate the necessity of inclusion of three-dimensional effects in the determination of lift and drag forces during rapid pitching and impulsively started maneuvers to/at high angle of attack. Following the guidelines of the NATO RTO AVT 202 test case, wind tunnel data was acquired for pure pitching cases from 0 to 45 degrees for an AR 4 flat plate using the University of Dayton Low Speed Wind Tunnel (UD-LWST) and compared to a 2D Discrete Vortex Method (DVM).
Results show that the DVM compares well to the wind tunnel data in the pre-stall region before the deformation of the wake at the trailing edge by the trailing edge vortex and show similar trends in the post-stall region. It is believed that these differences in post-stall occur due to 3D effects and discussion is provided to support this assertion. The DVM is also used to compare results of a 45 degree linearly accelerated impulsive start case to data obtained in an experiment at the AFRL Horizontal Free-surface Water Tunnel under conditions identical to the simulation. Comparing these results again demonstrates the that DVM matches well to the water tunnel data except in a region where it is believed 3D instabilities are responsible for effects in the flowfield that are not adequately modeled by the 2D DVM.
Available at: http://works.bepress.com/aaron-altman/31/