Hydrodynamic Drag Measurements on Complaint Surface Disks.
VOUGHT CORP ADVANCED TECHNOLOGY CENTER DALLAS TX
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The rotational drag of a disk, with interchangeable faces of compliant membranesubstrate combinations, has been measured in a water tank. A device for stretching a membrane uniformly and with repeatable results was designed, built, and successfully employed. The test procedure was selected as a simple means of screening potential drag reducing compliant surfaces as suggested by previous experimental and analytical studies. Nearly 40 different disks were tested in turbulent flow over a Reynolds number range of 1.7 - 3 million. Membrane thickness and tension, as well as substrate thickness, was varied. The membranes were bonded, unbonded, and separated by an air gap with respect to the substrates. The measured drag was compared to that of a corresponding hard reference disk. In most cases, no drag reduction occurred. The few measured drag reductions were within the estimated experimental inaccuracy.
- Fluid Mechanics