Title of dissertation: SCHLIEREN SEQUENCE ANALYSIS USING COMPUTER VISION Nathanial Timothy Smith, Doctor of Philosophy, 2013 Dissertation directed by: Professor Mark J. Lewis Department of Aerospace Engineering Computer vision-based methods are proposed for extraction and measurement of flow structures of interest in schlieren video. As schlieren data has increased with faster frame rates, we a...

Particle image velocimetry (PIV) is a quantitative optical method used in experimental fluid dynamics that captures entire 2D/3D velocity field by measuring the displacements of numerous small particles that follow the motion of the Abstract A detailed statistical assessment of seedless velocity measurement using Schlieren Image Velocimetry (SIV) was explored using open source Robust Phase Corr...

The characterization of a hypersonic impulse facility is performed using variety methods including Pitot probe scans, particle image velocimetry, and schlieren imaging to verify properties such as the velocity, Mach number, wall boundary layer thickness, freestream turbulence intensity levels. experimental results are compared numerical simulations with Ansys Fluent compare design operational c...

In the present work, methane (CH4) and hydrogen (H2) jet dynamics from a hollow-cone piezoelectric injector are experimentally investigated. The characteristics studied under effect of (1) pressure ratio, which is ratio injection (Pi) to chamber (Pch), (2) needle lift, (3) nozzle geometry (hollow-cone outwardly opening without any caps versus same with single-hole cap). Z-type schlieren imaging...

Two quantitative schlieren methods are assessed and compared: calibrated color schlieren (CCS) and background oriented schlieren (BOS). Both methods are capable of measuring the light deflection angle in two spatial directions, and hence the projected density gradient vector field. Spatial integration using the conjugate gradient method returns the projected density field. To assess the perform...

The requirements for beamforming in high intensity focused ultrasound (HIFU) for tissue destruction are substantially different than those for diagnostic imaging. High numerical aperture and CW efficiency are desirable for tissue destruction, while depth of focus and broadband sensitivity are key to good imaging. When the same transducer must be used for ablation and imaging some compromises mu...

A 15by 15-cm supersonic wind tunnel application of a one-dimensional laser beam scanning approach to shock sensing is presented. The measurement system design allowed easy switching between a focused beam and a laser sheet mode for comparison purposes. The scanning results were compared to images from the tunnel Schlieren imaging system. The tests revealed detectable changes in the laser beam i...

Bulk crystals cut and polished as spheres or cylinders are unique tools for measuring the angular distribution of any linear or nonlinear optical property as well as for designing widely and continuously tunable parametric devices. The aim of this article is to describe the specific techniques of shaping such high quality samples, and their use in methods of optical measurements and devices tha...