AN EXPERIMENTAL INVESTIGATION OF THE UNSTEADY FLOWS ABOUT SPHERES AND DISKS.
MICHIGAN UNIV ANN ARBOR DEPT OF AEROSPACE ENGINEERING
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The various features of unsteady three-dimensional bluff body flow fields have been studied in a towing channel filled with glycerol-water mixtures and equipped with an air bearing supported model carriage. Steady drag coefficients for the sphere and disk agreed with existing data except for the disk in the range 100 Re sub d 1000 where C sub D is as much as 50 lower than previous results. Peak-to-peak moment coefficients developed on a disk are of the order of 0.007 for 100 Re sub d 500 at nondimensional frequencies of 0.10 fdU 0.14. The sphere wake was seriously disturbed by the sting model support, however, the unsteady side force coefficient is of the order of 0.02 to 0.10 for 270 Re sub d 560. Flow visualization studies using hydrogen bubbles were used to relate the unsteady forces to the shedding of vortices in the wake. Author
- Fluid Mechanics