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Comparison of the Aerodynamic Characteristics of the Eppler-197 and Modified Eppler-197 Airfoil Sections at Mach Number from 0.4 to 0.75

The objective of this paper is to study the aerodynamic characteristics of the modified Eppler-197 airfoil sections at high-subsonic Mach number. The mean-camber line of Eppler-197 airfoil section was used as the basic mean-camber line for the two modified airfoils. The surface around the mean-camber was created by using the symmetrical airfoil profiles, NACA64012 and NACA65012. The computational fluid dynamic code, ANSYS FLUENT, was used to determine the lift, drag, pitching-moment characteristics and drag-divergence Mach number of the modified airfoils. The flow condition in this study was at Reynolds number 3×106 and the Mach number varies from 0.4 to 0.75. The angle of attack was varied from the –2° to 6°. The results from calculation were compared with the data of the original Eppler-197 profile. The study shows that the modified profiles have better aerodynamic characteristics at all Mach number range. The lift-to-drag ratio of the modified profiles are higher than the original profile. The drag-divergence Mach number of modified airfoils increases between 0.69 percent to 7.15 percent at lift coefficient from 0.1 to 1.1. The rate of drag rise above the drag-divergence Mach number of the modified profiles are lower than the original profile. The pitching moment does not have significantly change.