Large scale stereoscopic PIV investigation of the flow at a high lift wing configuration with an active Krueger device

Abstract

This thesis describes the implementation and evaluation of a double SPIV system for flow field measurements in one of the validation experiments of the Unsteady High-lift Aerodynamics – Unsteady RANS validation project (UHURA) in the frame of Horizon 2020. The main objective of this study is to provide an extensive database to determine the aerodynamic properties and flow characteristics of a slotted Krueger flap during the deployment and retraction phases. For this purpose, the DLR-F15LS wing model was equipped with an actuated Krueger device to be tested at the DNWLLF wind tunnel during spring 2022. During this campaign, measurements of steady and unsteady pressures along with phase-locked Particle Image Velocimetry were performed to achieve high-quality data for several numerical simulation approaches (RANS and LES) within the UHURA project. The flow measurements revealed the importance of a precise alignment of the light sheet with respect to the calibration plane of each camera view. Further misalignments due to vibrations of the cameras, which can lead to unacceptably large disparity errors, require single-time-step disparity correction schemes in order to obtain correct 3C-2D velocity vector fields. In combination with severe laser reflections at the Krueger flap for the downstream cameras, not all SPIV results could be made available in time. However, the 2C-2D PIV results highlight well the unsteady and transient behavior of the flow during the deployment and retraction of the Krueger device.