AN EXPERIMENTAL INVESTIGATION ON THE FREESTREAM TURBULENCE UPSTREAM OF A SWEPT WING

摘要

A considerable amount of theoretical and experimental research exists on the amplification of vorticity at the edge of the boundary layer near the stagnation point in two-dimensional flows. Experiments on cylinders, flat plates and wings have confirmed the theory of vorticity amplification. Here, the phenomenon is investigated when a sweep angle is added to the model, introducing a spanwise velocity component parallel to the leading edge. Two experimental investigations are presented, one on a straight cylinder and one on a swept wing NACA0050. The aim is to measure variations of the fluctuating component of the velocity close to the leading edge, investigating the difference between a swept and an unswept case. The experiments were carried out using two-dimensional Laser Doppler Anemometers (LDA), which measure two components of the velocity. For the cylinder, the behaviour of the fluctuating components confirms the predictions of the theory. In the case of the swept swing, where no systematic theory is available, a distinctive but less organized amplification of vorticity has been observed.