Comparisons of theoretical methods for predicting airfoil aerodynamic characteristics

A number of airfoils have been tested in the Pennsylvania State University low-speed low-turbulence wind tunnel, and the results of these tests are compared with those predicted using several well-known theoretical methods. The theoretical methods used are the potential-flow/integral boundary-layer methods XFOIL 6.96 and PROFIL07 and the Reynolds-averaged Navier-Stokes solverOVERFLOW2.2e. This version of the OVERFLOWsolver contains an implementation of the transitional shear-stress transport turbulence model developed by Langtry and Menter ("Correlation-Based Transition Modeling for Unstructured Parallelized Computational Fluid Dynamics Codes," AIAA Journal, Vol. 47, No. 12, 2009, pp. 2894-2906). This model is capable of capturing the influence of transition on the flowfield through a local-correlation method. The airfoils considered for this study are the E 387, S805, PSU 94-097, HTR1555, S903, and S824. Although none of the theoretical methods considered were consistently the best overall, all codes predicted the drag well in the low-drag regions of these airfoils and the codes incorporating integral boundary-layer methods generally agreed better with the experimental data. The methods also all showed inconsistencies in predicting the maximum lift coefficient, with XFOIL and OVERFLOWfrequently overpredicting this value.