Time-resolved PIV measurements of a tip leakage flow

摘要

Time-resolved PIV and time-resolved stereo PIV measurements are carried out in the tip leakage vortex of a single non-rotating airfoil placed in the potential core of a flanged rectangular jet in free field conditions. The experiment is based on the improvement of an existing rig: a cambered airfoil (NACA5510) now mounted with a 16: 5 degrees +/- 0: 5 degrees angle of attack between two horizontal plates, a 10 mm gap being maintained between the airfoil tip and the lower (casing) plate. The mean flow velocity is 70 m/s, which corresponds to a 0.2 Mach number and a chord-based Reynolds number of 933, 000. Unlike in the former experiment carried out with this rig, the boundary layer thickness is now smaller than the gap, which significantly reduces the interaction between the upstream turbulence and the airfoil leading edge as well as the resulting interaction noise. The measurements described here include the far field. The upstream flow is characterised with hotwire anemometry. LDV profiles are also obtained in the tip leakage region and compared to the PIV measurements. The experiment is also designed to provide validation data for unsteady CFD computations of the same configuration as shown in a companion paper.