Scale-model tests of airfoils in simulated heavy rain

Abstract

This paper discusses some of the surface water characteristics obtained in simulated heavy rain experiments conducted at the NASA Langley Research Center. The objective was to measure water film distributions and discrete film thicknesses on several two-dimensional model wings. The water film distributions on the upper surfaces are shown in photographs taken from cameras mounted above the models; the film thickness data were obtained using resistance sensors mounted flush with the upper and lower wing model surfaces. It was observed that two different clean wing models developed similar water film patterns consisting of a continuous sheet that extended to midchord and broke off in runoff streams. The water film pattern on the flapped model differed from the clean wing configuration. On the upper surface of the flapped model, the continuous sheet was thinner and a great deal of water was observed in and around the flap gaps.