Optical Wall Shear Stress Measurements on the Leeward Side of a Delta Wing

Abstract

A simple setup for oil-film interferometry with white light was used to determine the flow topology and the wall shear stress on a delta wing at different angles of attack. Weil reproducible and plausible comprehensive wall shear stress distributions on the upper side of the delta wing could be calculated from experimental interference images. For the image evaluation, a new algorithm was proposed and developed, helping to compute automatically and quickly the local oil film thickness from a sequence of interference images. Numerical simulations with the DLR TAU-code were executed and compared with the experimental results.