Experimental Results for a Low-Reynolds-Number Airfoil in a Low-Turbulence Wind Tunnel

The Pennsylvania State University (PSU) 94-097 airfoil was originally designed in the mid-1990s for use on winglets of high-performance sailplanes. This design problem is difficult because this application requires the airfoil to operate over a wide range of Reynolds numbers, from 0.7 × 10⁵ to 1.0 × 10⁶. At that time, over two decades ago, to validate the tools as well as the design itself, high-quality measurements of section characteristics and pressure distributions were made in the PSU low-speed low-turbulence wind tunnel with Reynolds numbers from 2.4 × 10⁵ to 1.0 × 10⁶. In addition to free-transition measurements, potential drag reductions using artificial turbulators were explored. More recently, this model was retested in the same facility at Reynolds numbers down to 1.0 × 10⁵. In addition, because this airfoil has been successfully employed on model aircraft and unmanned aerial vehicles, its performance using a simulated simple flap/aileron was measured and found to provide the necessary lift coefficient range to support the flight envelope without significant increases in drag. In this regard, it is comparable to similar flapped-equipped airfoils. Finally, as with the results from the original tests, with the exception of the maximum lift coefficient, theoretical predictions using well-known codes are found to be in good agreement with the wind-tunnel measurements.