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An experimental study of geometrical effects on the drag and flow field of two bluff bodies separated by a gap

Koenig, Keith and Roshko, Anatol (1985) An experimental study of geometrical effects on the drag and flow field of two bluff bodies separated by a gap. Journal of Fluid Mechanics, 156 . pp. 167-204. ISSN 0022-1120. http://resolver.caltech.edu/CaltechAUTHORS:KOEjfm85

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Abstract

This paper describes an experimental investigation of the shielding effects of various disks placed coaxially upstream of an axisymmetric, flat-faced cylinder. Remarkable decrease of the drag of such a system was observed for certain combinations of the basic geometric parameters, namely the diameter and gap ratios. For such optimum shielding the stream surface which separates from the disk reattaches smoothly onto the front edge of the cylinder, in what is close to a ‘free-streamline’ flow; alternatively, the flow may be viewed as a cavity flow. For the optimum as well as other geometries, flow pictures, pressure distributions and some LDV measurements were also obtained. From these, several flow regimes depending on the gap/diameter parameters were identified. Variations on the axisymmetric disk–cylinder configuration included a hemispherical frontbody, rounding of the front edge of the cylinder and a change from circular to square cross-section.


Item Type:Article
Additional Information:Copyright © 1985 Cambridge University Press. (Received 11 July 1984) This paper is based on work for the Ph.D. thesis by one of us (Koenig 1978). Some early results were presented at the 1976 General Motors Symposium on Aerodynamic Drag Mechanisms (Roshko & Koenig 1978). The work was initiated with assistance from a Ford-Exxon Energy Research Grant and continued with support from National Science Foundation Grants ENG 75-03694 and ENG 77-23541. In addition, we are grateful for assistance in various forms from F.H. Clauser, D.E. Coles, P.E. Dimotakis, T. Liepmann and G. Lundgren.
Record Number:CaltechAUTHORS:KOEjfm85
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:KOEjfm85
Alternative URL:http://dx.doi.org/10.1017/S002211208500204X
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10106
Collection:CaltechAUTHORS
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Deposited On:13 Apr 2008
Last Modified:26 Dec 2012 09:56

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