Flow over a Magnetically Suspended Cylinder in an Axial Free Stream

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Burs t#; rec#: 7; 1 (7), Date: 11/3/2004, Tim e: 01:02:16:812PM
Analog inputs: 10 000; 10 000; 10 000; 10 000
Figure 14. Instantaneous velocity vector over the L/D=3 cylinder model, Re D =10,000
Even though the mean velocity profiles of the separating and reattaching flow looks well-defined in velocity vector
as well as in mean streamlines (not shown for brevity), it is worthwhile to note the complex flowfield involved. Figure
14 is an instantaneous velocity vector used to compute the averaged velocity profile in Fig. 12, and it shows large-scale,
convoluted eddy motion that will be pertinent in investing the possible control of the shear layer at wide Reynolds
number range and turbulence level.
The PIV measurement of the wake behind the sting-mounted model was also performed in water. When the wake
flow was measured with the sting placed upstream, a disturbance from the upstream was detectable in the
instantaneous velocity field. The flowfield measurements in the wake using a PIV system behind a magnetic suspended
model are of critical importance and are being scheduled.
IV. Conclusion
The drag coefficient variation of circular cylinder placed in an axial flow was obtained over a wide range of fineness
ratio. In order to avoid flow interference with any model support and to insure axisymmetry of the flow, the
experiment was conducted using a magnetic suspension and balance system. The flow field in the wake, boundary
layer as well as the behavior of the separated shear flow from the leading edge was studied to collaborate the measured
drag variation.
Acknowledgements
The present study was supported by the Japan Society for Promotion of Science, Ministry of Education and Culture,
Japan. Authors acknowledge assistance of Mr. Tetsuya Kunimasu and Dr. Shinichi Suda during the JAXA experiment.
Author PVL performed the water channel experiment at Syracuse University with author HH and they thank Prof.
Harry Hoeijmakers at Twente University for his arrangement.
References.
1 Blevins, R.D., Applied Fluid Dynamics Handbook, Van Nostrand Reinhold Company, NY, 1984.
2 Hoerner, S. F., Fluid Dynamic Drag, published by author, 1958, p.3-12.
3 Eiffel, G., “The Resistance of the Air and Aviation,” (translated by J. C. Hunsaker), London: Constable Co., Boston: Houghton,
Mifflin & Co. 1913.
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American Institute of Aeronautics and Astronautics