Development of new methods for analysis of LPT data and application to high-subsonic jet measurements

Abstract

Lagrangian particle tracking enables the accurate measurement of the position, velocity and acceleration of particles moving within fluid flows. Beyond the particle positions in each time step, an actual track of the individual particle is available over time. This can be exploited for new analysis methods that use this continuous nature of the tracks to improve binned statistics of the flow. Instead of considering just particle positions at each sampling time instance the movement of the tracked particle between those time steps can provide additional information. In the case of binning based averaging methods this results in better convergence of the statistics for a given amount of data. We apply such methods to a multi-pulse Shake-The-Box (STB) measurement of a Mach 0.84 jet in air and generate high resolution two-point correlation maps of the flow. Coherent structures in the shear layer are further investigated using event orientated conditional averaging based on quadrant analysis. As a novel approach for using the Lagrangian nature of the measurement data, we additionally show a control volume balance based calculation approach, which together with bin based statistics could provide a pathway towards investigating balance equations of flow quantities