Large scale volumetric flow measurement on a turbulent boundary layer

Abstract

The aim of this work is to capture the spatiotemporal dynamics of large-scale flow structures in a turbulent boundary layer flow in a volumetric and time-resolved way. The applied means are dense Lagrangian Particle Tracking of Helium-Filled Soap Bubbles (HFSBs) using the Shake-The-Box (STB) algorithm and a subsequent interpolation to a regular grid using the physically regularized FlowFit method. The presented experiment was performed as a pre-test to a full campaign to be held in August 2018 at the Atmospheric wind tunnel at the University of the armed forces in Munich, Germany. This test demonstrates the principle applicability of the measurement techniques to a low-speed wind tunnel environment and shows that high spatial accuracy and resolution can be reached despite of a large measurement volume. Problems were encountered achieving a homogeneous bubble distribution and in deploying large amounts of bubbles, while not disturbing the flow.