Accession Number:

ADA090585

Title:

Measurements of Unsteady Turbulent Boundary Layers with Pressure Gradients.

Descriptive Note:

Final rept. 1 Apr 76-31 May 79,

Corporate Author:

SOUTHERN METHODIST UNIV DALLAS TX DEPT OF CIVIL AND MECHANICAL ENGINEERING

Personal Author(s):

• Simpson,R. L.
• Chew,Y.-T.
• Shivaprasad,B. G.

Report Date:

1980-08-01

Pagination or Media Count:

58.0

Abstract:

Although periodic unsteady turbulent boundary layers are of real significance in turbomachines and helicopters, little experimental velocity distribution data have been obtained, especially with flow separation. An unsteady turbulent boundary layer facility was developed at SMU to produce almost-sinusoidal waveforms for practical reduced frequencies of the order of unity. Separation occurred on the flat test-wall of the diverging test section. An active boundary layer control system was developed to prevent separation on non-test walls of the test section. Detailed measurements using laser and hot-wire anemometry were made at reduced frequencies of 0.55 and 1.0. Well upstream of separation the flow away from the wall behaved in a quasi-steady manner. Near the wall an unexpected phase shift occurs, which is incompletely explained and may be an instrumentation and apparatus dependent effect.

Descriptors:

• *PRESSURE GRADIENTS
• *TURBULENT BOUNDARY LAYER
• *NONUNIFORM FLOW
• TURBULENCE
• PHASE STUDIES
• HELICOPTERS
• SHEAR STRESSES
• FLOW SEPARATION
• REYNOLDS NUMBER
• HOT WIRE ANEMOMETERS
• EDDY CURRENTS
• TURBOMACHINERY
• PERIODIC VARIATIONS
• LASER VELOCIMETERS

Subject Categories:

• Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE