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Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part II: Supersonic Flow

Bonanos, Aristides M. and Bergthorson, Jeffrey M. and Dimotakis, Paul E. (2009) Molecular Mixing and Flowfield Measurements in a Recirculating Shear Flow. Part II: Supersonic Flow. Flow, Turbulence and Combustion, 83 (2). pp. 251-268. ISSN 1386-6184.

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Fundamental aspects of mixing between two gaseous streams in a complex geometry are studied and discussed. In the present paper, a supersonic top-stream is expanded over a 30° ramp, through which a secondary lower-stream is injected. The mass flux through the secondary stream is purposely insufficient to provide the entrainment requirements of the resulting shear layer, causing it to attach to the lower guidewall. Part of the shear layer fluid is directed upstream forming a recirculation zone, with enhanced mixing characteristics. The pressure coefficient of the device is quantified as a function of velocity ratio. The effect of heat release on the pressure coefficient is also reported. Molecular mixing was measured employing “flip” experiments based on the hypergolic hydrogen-fluorine chemical reaction. The amount of mixing for the expansion-ramp geometry is found to be higher than in classical free shear layers. However, as in free shear layers, the level of mixing decreases with increasing top-stream velocity. Results for a similar configuration with subsonic/transonic flow in the top stream are reported in Part I of this two-part series.

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Additional Information:© 2009 Springer. Received: 6 March 2008. Accepted: 2 January 2009. Published online: 1 February 2009. The authors would like to acknowledge constructive discussions with C. Bond and G. Matheou. D. Lang assisted with the computers and electronics associated with the facility control and data acquisition. The experiments reported here were made possible with the assistance of E. Dahl in the design, maintenance and operation of the facility. This work was funded by the AFOSR under Grants FA9550-04-1-0020 and FA9550-04-1-0389, whose support is gratefully acknowledged.
Funding AgencyGrant Number
Air Force Office of Scientific Research (AFOSR)FA9550-04-1-0020
Air Force Office of Scientific Research (AFOSR)FA9550-04-1-0389
Subject Keywords:Turbulence; Mixing; Backward-facing step; Shear layer; Recirculation
Issue or Number:2
Record Number:CaltechAUTHORS:20090828-231037589
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Official Citation:Bonanos, A.M., Bergthorson, J.M. & Dimotakis, P.E. Flow Turbulence Combust (2009) 83: 251.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15471
Deposited By: George Porter
Deposited On:14 Sep 2009 21:13
Last Modified:03 Oct 2019 00:58

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