Computer Assisted Tomography for Three-Dimensional Flow Visualization in Transonic Wind Tunnels

ABSTRACT:We propose to develop a 3D tomographic background-orientated Schlieren measurement technique, including hardware setup and post-processing software to produce 3D visualization of compressible flow features in large transonic wind tunnels. Such an approach relies on a novel synthetic self-similar fractal-based background and explores various tomographic reconstruction algorithms that will yield pertinent volumetric information such as the 3D structure of shock waves, vortices, turbulent wakes, boundary layers, etc. Hybrid wave-optics and ray-tracing simulations will be carried out to test and evaluate the accuracy and efficiency of the various post-processing tomographic 3D reconstruction algorithms as well as to determine testing hardware/software requirements. Particular attention will be spent toward enabling the 3D reconstruction and visualization code(s) to run in near real-time to allow for a more immediate feedback during wind tunnel testing.BENEFIT:A near real-time 3D background-orientated Schlieren measurement technique would improve compressible flow feature characterization in transonic wind tunnels. This would greatly increase the understanding of the 3D structure of such flow features in a time frame that would allow for immediate feedback to researchers running the wind tunnel tests. The proposed approach would produce a quantifiable accuracy, as determined through simulation (in Phase I) and tunnel testing (in Phase II), for the post-processing tomographic 3D reconstruction algorithms. Such a measurement capability would find wide-ranging use in aero-dynamic testing environments such as wind tunnels and flight testing where 3D flow visualization is desired, especially for CFD validation. Alternative uses for such measurement technology would be for developing and validating fluid simulations in computer graphics.