Experimental Investigation of the Aeroelastic Behavior of a Laminar Airfoil in Transonic Flow

TLDR: In this article, the authors investigated the unsteady flow around an oscillating CAST 10-2 airfoil model at Mach numbers relevant for cruise flight of transport aircraft and provided a deeper insight in the nonlinearity of the lift polar.

Abstract: The unsteady flow around an oscillating CAST 10-2 airfoil model was investigated at Mach numbers relevant for cruise flight of transport aircraft. Unsteady pressure sensors and hot-film anemometry were used to characterize the unsteady flow and the laminar-turbulent transition on the airfoil. Results are presented for subsonic and transonic Mach numbers focusing at the transonic regime at M = 0.750. Thereby steady measurements serve as a starting point to gain a better understanding of flow physics. Transition positions, pressure distributions and the resulting lift coefficients are discussed and provide a deeper insight in the nonlinearity of the lift polar. Unsteady hot-film signals are discussed for one period and reveal a temporal asymmetry of the flow state and of the integral values lift and moment coefficient. Derivatives from these coefficients as functions of reduced frequency and amplitude are presented.