Comparison of Roughness Resistance as Measured by Flat Plate and Rotating Disk.
Abstract
The resistance of four surface roughness, formed by mixing paint with different grit sizes, have been investigated using a flat plate friction plane and a rotating disk apparatus. The purpose of the experiments was to compare the results obtained with the plate and disk. An attempt was made to keep the roughnesses between the plate and disks of each plate-disk set identical but only with partial success. The plate and disk results were compared by first determining the boundary-layer similarity-law-roughness characterization delta B from the measured resistances of the plates and torques of the rotating disks. The values of delta B were then used to estimate typical full-scale friction drags as predicted from the plate and disk data. Taking into account the differences between roughness height measurements taken on the plates and disks the compared extrapolated total friction drags for three of the four roughnesses were within 10 percent of each other. The results from the fourth and largest roughness show a larger disagreement between extrapolated values of total frictional drag. Except for Roughness 3, the discrepancies between measured changes in drag due to roughnesses on disks and plates were as much as 100 percent. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1980
- Accession Number
- ADA081455
Entities
People
- David W Taylor
- J. L. Power
- J. Libby