Relation between the Surface Friction of Plates and their Statistical Microgeometry
Interim rept. Apr 1979-Jan 1980,
TEESSIDE POLYTECHNIC MIDDLESBROUGH (UNITED KINGDOM) DEPT OF MECHANICAL ENGINEERING
Pagination or Media Count:
An attempt is made to relate the geometry of nominally flat surfaces to their resistance to fluid flow. The experimental work was carried out in an open-flume, 20 metres in length, 30 cm wide, and 30 cm deep. The flow measurements were carried out over a range of free stream velocities from 35 cm sec to 85 cmsec. Hot film anemometry using a single sensor was used to measure the boundary layer velocity profile development along a 2.4 metre section of the channel floor which provides the base for the test surfaces. The velocity profiles are analysed to determine the surface friction coefficient using the simplified momentum integral equation as well as the logarithmic inner law approach. The test surfaces, including a 4.8 metre long replica of a ship hull surface, were examined using a number of surface measurement instruments capable of recording surface wavelengths from microns to metres. Surface profiles were recorded and digitised and the data statistically analysed to give an overall characterisation of the surfaces under investigation using both amplitude and spatial parameters.
- Marine Engineering
- Fluid Mechanics