Free-Flight Measurement of the Drag Forces on Cylinders in Event DICE THROW.
DEFENCE RESEARCH ESTABLISHMENT SUFFIELD RALSTON (ALBERTA)
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Previous determinations of drag coefficients for both steady and unsteady flow are reviewed for all reported experiments at critical and supercritical Reynolds numbers. The unsolved problems remaining from earlier DRES work were found to be end effects, dust drag loading, the discrepancies between steady and unsteady flow drag forces, and the need for a further data analysis. A new analysis is also presented for the drag coefficient as a function of flow Mach number and cylinder length-diameter ratio. A plan of test is presented for drag force measurements on cylinders during Event DICE THROW, a 628-ton ANFO explosion held in October 1976. The objectives of this experiment were to provide drag force support data for the lattice mast and all antennas in Event DICE THROW, and to extend the table of data for drag coefficients to diameters up to 18 inches. The free-flight measurement technique, using both cameras and velocity transducers for data sources, was employed on seven cylinders at 20, 10 and 7 psi overpressure levels. The expected motion of each cylinder was calculated, based on the predicted value for the drag coefficient. Finally, suggestions for the data analysis and for further research in this area are discussed. Author