Investigations of Flow Phenomena Over a Flat Plate and NACA0012 Airfoil at High Angles of Attack

摘要

In the present study, the flow and aerodynamic features of a sharp trailing edged flat plate airfoil are systematically compared with NACA0012 airfoil. The studies are conducted for three different Reynolds numbers 1.89 x 10(5), 2.83 x 10(5)and 3.78 x 10(5)and angles of attack 20 degrees, 25 degrees and 30 degrees. The present study shows that the occurrence of vortex shedding phenomena for the flat plate is substantially different from NACA0012 airfoil. Further, the re-attachment location of the shed vortices is closer to the trailing edge for the flat plate, whereas for NACA0012 airfoil it occurs at a certain distance upstream of the trailing edge. The NACA0012 airfoil generates higher lift coefficients at a higher Reynolds numbers of 2.83 x 10(5)and 3.78 x 10(5), whereas for the flat plate it occurs at a lower Reynolds number of 1.89 x 10(5). The spectra of lift coefficient reveal that the amplitude of the primary shedding frequency dominates for the flat plate and NACA0012 airfoil at lower and higher Reynolds numbers of 1.89 x 10(5)and 3.78 x 10(5), respectively, while it becomes almost same for an intermediate Reynolds number of 2.83 x 10(5). The present study reveals that the drag coefficient at high Reynolds number (3.78 x 10(5)) is directly proportional to the initial merging point of the two shed vortices for both the flat plate and NACA0012 airfoil.