Static pressure and mean velocity data were obtained in a relaxing shear driven three-dimensional incompressible turbulent boundary layer flow produced by a swept rectangular step. The nominally 10 cm (4 in.) thick boundary layer had a freestream velocity of approximately 25 m/sec (80 ft/sec). The two steps investigated were each 3.8 cm (1.5 in.) high by 18.4 cm (7 .25 irt.) long and at angles of 30° and 45° to the transverse wind tunnel direction.
Pressure gradients were determined by taking the derivative of least-squares curve fits to the static pressure data. Close to the trailing edge reattachment region, the maximum·gradient was·0.8 kPa/m (5 psf/f) for the 30° step and 0.4 kPa/m (2.5 psf/f) for the 45°step. As expected, a region of nominal pressure gradient (0.03 kPa/m or 0.2 psf/f compared to 1.6 kPa/m or 10 psf/f for a pressure driven flow) was found at greater than 36 cm (14 in.) down.stream of the trailing edge of each step.
The wall crossflow angle decayed from 67° at 15 cm (6 in.) behind the trailing edge to 9° at 66 cm (26 in.) for the 30° step. In the same region, the crossflow angle decayed from 45° to 6° for the 45° step. The decay or relaxation was found to be much faster in the near-wall region and in the region close to the trailing edge.
A defect in the streamwise velocity profiles indicated that the flow was dominated by the separation and reattachment over the step. For future shear driven investigations, a lower, more streamlined wing-type body is recommended to produce a moderately skewed boundary layer without dominant separation effects. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/71095 |
| Date | January 1979 |
| Creators | Nelson, Douglas J. |
| Contributors | Mechanical Engineering |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | en_US |
| Detected Language | English |
| Type | Thesis, Text |
| Format | xi, 171, [2] leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 5630085 |
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