Analysis and Visualization of 3-C PIV Images from HART II using Image Processing Methods

Abstract

In this paper, three-component particle image velocimetry (3-C PIV) measurements within the wake of a helicopter rotor from the HART II test are analyzed. These PIV-images are quite a challenge as the noise due to the measurement method and the inherent turbulence of the flow can not be distinguished. Furthermore, features are often hidden by a mean flow, which is influenced by vortices and therefore not easy to determine. The authors present some image processing methods adapted to these vector fields for the computation of position, size, and direction of the vortices in this data. These methods are quite robust in terms of noise and independent of any mean flow and therefore appropriate for this analysis. The results of the analysis allow a more descriptive and intuitive visualization of the vortices.