Turbulent flow ballistics facility for particle momentum transfer studies

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Abstract
This paper describes the calibration and use of an experimental installation which was specifically designed for the quantitative measurement of the drag coefficient of single particles moving with a turbulent fluid. The installation consisted of an 8‐in. I.D. wind tunnel with an 18‐ft. test section, preceded by an inlet grid arrangement designed to provide a flow with a symmetrical mean velocity profile and a flat central core having a nonperiodic spectrum of turbulence. The particles were launched at controlled entrance velocities into the core in a nonrotating manner by means of a particle accelerator, and axial motion was obtained. A hot‐wire anemometer was used to measure the flow turbulence parameters at two Reynolds numbers by means of probes inserted at various distances above the inlet grid section. These measurements included the radial and axial intensities, the axial turbulent energy spectrum, and the macro and microscales. An accurate record of the particle velocity history was provided by a new radiotracer velocity measurement technique. This information was then processed by an IBM‐650 program which supplied the drag coefficient as well as the instantaneous particle velocity, acceleration, rate of change of acceleration, Reynolds number, and relative turbulence intensity from the time‐distance data. The experimental facility was found to be well suited for general studies of momentum transfer phenomena in particulate systems at high relative intensities.