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Background Oriented Schlieren Applied to Study Shock Spacing in a Screeching Circular JetBackground oriented schlieren (BOS) is a recent development of the schlieren and shadowgraph methods. The BOS technique has the ability to provide visualizations of the density gradient in both the axial and radial directions. The resultant magnitude of the density gradients allows for comparison with shadowgraph images. This paper first compares data obtained by the BOS and shadowgraph techniques at identical conditions in a free jet. The patterns and spacing of the shock trains obtained by the two techniques are found to be consistent with one another. This provides confidence in the shock spacing measurement by the BOS technique. Due to its simpler setup, BOS is then applied to investigate the shock spacing associated with the screech phenomenon, especially during stage jumps. Screech frequencies from a 37.6 mm convergent nozzle, as a function of jet Mach number (M(sub j)), are shown to exhibit various stages. As many as eight stages are identified with the present nozzle over the range 1.0 < M(sub j) <1.7. BOS images are acquired at various screech conditions and the shock spacing is examined as a function of M(sub j).
Document ID
Document Type
Conference Paper
Clem, Michelle M.
(NASA Glenn Research Center Cleveland, OH, United States)
Zaman, Khairul B. M. Q.
(NASA Glenn Research Center Cleveland, OH, United States)
Fagan, Amy F.
(NASA Glenn Research Center Cleveland, OH, United States)
Date Acquired
August 25, 2013
Publication Date
January 9, 2012
Subject Category
Fluid Mechanics And Thermodynamics
Report/Patent Number
Meeting Information
50th AIAA Aerospace Sciences Meeting(Nashville, TN)
Distribution Limits
Work of the US Gov. Public Use Permitted.
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