Determination of the critical reynolds number for flow over symmetric NACA airfoils
Type :
Conference paper
Publication Status :
Published
Access :
restrictedAccess
Abstract
The determination of the critical Reynolds number is of practical importance in many engineering applications, particularly in determining the aerodynamic characteristics of air vehicles. In this study, we numerically investigated the laminar-turbulent transition location over NACA 0012, 0015, and 0018 airfoil profiles in order to determine their lower critical Reynolds number. To this end, a CFD FORTRAN code was developed based on the hybrid viscous-inviscid interaction method with an incorporated eN transition method to model the boundary layer flow around airfoil profiles. The results, in general, indicated that the laminar-turbulent transition location over an airfoil is strongly dependent on the Reynolds number and moves toward the downstream as the Reynolds number decreases. The lower critical Reynolds number was then defined as the velocity at which the flow becomes laminar over the airfoil, which corresponds to the conditions that the transition point located at the trailing edge of the airfoil. The lower critical Reynolds number for flow over NACA 0012, 0015, and 0018 airfoils were, therefore, determined to be 1 × 105, 5 × 104, and 3.5 × 104, respectively. Moreover, the variations of the transition location with the angle of the attack showed that the transition point moves toward the leading edge of the airfoil as the angle of attack increases.
Source :
2018 AIAA Aerospace Sciences Meeting
Date :
2018
Publisher :
American Institute of Aeronautics and Astronautics Inc, AIAA
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