Stereo particle shadow velocimetry for turbulent flow characterization

Particle shadow velocimetry (PSV) is an optical, LED-based flow diagnostic technique that images a backlit flow field and uses inverted images to quantify the velocity. The planar, two-component version of this measurement technique has been shown to produce reasonably accurate results up to third and fourth order statistics. The aim of this work is to show that the turbulent spectra and reduced order modeling analysis from PIV data are comparable to the same measured with PSV. This type of analysis has never been done on a stereoscopic PSV measurement, so the limitations of such analysis for this measurement technique should be demonstrated. The flow field of a small jet is measured using stereo PIV and stereo PSV and the through-plane velocity is compared. A second test using a fully-developed pipe flow in glycerin is used to analyze the velocity mean, variance, and the temporal and spatial spectra for each measurement at several locations. Reduced order modeling in the form of proper orthogonal decomposition is also used to analyze and filter the noise in the measurements.