Underwater Investigation of Stall Onset on an Elliptic Profile via Temperature-Sensitive Paint

Abstract

The onset of stall on an elliptic profile with 16% relative thickness is the focus of the present work. The experiments were conducted in the GWB water tunnel of TU Braunschweig on a two-dimensional model with a chord length c = 0.2 m. The model upper surface was equipped with a Temperature-Sensitive Paint (TSP) for the global, non-intrusive, time-resolved measurement of the surface temperature distribution. In order to enhance the tempe-rature differences induced by the flow on the surface, the model surface temperature was in-creased by an internal flow of warm water. The TSP data were acquired over a mid-span re-gion of approx. 0.2 × 0.3 m^2 at a frequency of 1 kHz. The model was also equipped with a row of pressure taps to measure the surface pressure distribution. The experiments were performed at two chord Reynolds numbers (Re = 2.5 and 5.0 × 10^5) for a wide range of angles-of-attack (−4° <= AoA <= 30°), thus enabling the study of a variety of flow conditions, including laminar-turbulent transition and flow separation. The final contribution will provide the temporal development of the surface temperature at pre-stall, stall and post-stall conditions, and an evaluation of the onset of stall.