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Optical Engineering • Open Access

High-speed digital visualization and high-frequency automated shock tracking in supersonic flows
Author(s): Brenda H. Timmerman; Andrew J. Skeen; Peter John Bryanston-Cross; Paul G. Tucker; R. J. Jefferson-Loveday; James D. Paduano; G. R. Guenette

Paper Abstract

A low-cost, robust, versatile digital shadowgraph visualization system is presented that provides a fast nonintrusive diagnostic for unsteady high-speed flows. The technique is particularly designed for real-time automated tracking of shock positions, enabling high-speed active shock control. The visualization system is based on a high-intensity white LED light source combined with a CMOS-imaging sensor, providing the system with three modes of operation: (1) high-resolution overall instantaneous visualization; (2) high-resolution visualization showing spatial-temporal variations in the flow field, allowing direct identification of areas where changes occur; (3) adjustable windowed visualization at reduced resolution at high frame rate (currently up to 980 Hz). Experimental results are presented together with numerical simulations based on the high-accuracy NTS Navier-Stokes solver and Roe's flux difference splitting method. The flow studied is an adjustable underexpanded jet flow coming from a nozzle that is placed in a counterflowing Mach-2 flow. The interaction of the two flows results in a complex shock and expansion pattern, providing a challenging configuration for the numerical flow solver. By modulating the jet, high-frequency changes are induced in the interaction pattern, allowing simulation of shock movement in a supersonic inlet. Good correspondence between measured and numerical shock position and angle is found.

Paper Details

Date Published: 1 October 2008
PDF: 8 pages
Opt. Eng. 47(10) 103201 doi: 10.1117/1.2992621
Published in: Optical Engineering Volume 47, Issue 10
Show Author Affiliations
Brenda H. Timmerman, The Univ. of Warwick (United Kingdom)
Andrew J. Skeen, The Univ. of Warwick (United Kingdom)
Peter John Bryanston-Cross, The Univ. of Warwick (United Kingdom)
Paul G. Tucker, Swansea Univ. (United Kingdom)
R. J. Jefferson-Loveday, Swansea Univ. (United Kingdom)
James D. Paduano, Massachusetts Institute of Technology (United States)
G. R. Guenette, Massachusetts Institute of Technology (United States)


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