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Effects of a modified leading edge on noise and boundary-layer transition in a rod-wall sound shield at Mach 5A version of a rod wall sound shield was tested in the Mach 5 pilot quiet tunnel over a range of unit Reynolds numbers from 10 to 35 million per meter. The model was modified by inclining the leading edge plates to produce an initial 2 deg expansion to ascertain the sensitivity of boundary layer transition to leading edge disturbances. Rod surface pitot pressures, mean free stream pitot pressures, and static pressures on the rods and plenum walls were measured. Hot-wire measurements were also made in the model and nozzle free stream at a unit Reynolds number of 15 million per meter. The surface pitot pressures indicated that transition was much farther forward than for the previous tests due to the leading edge modification and minor fabrication flaws in the model. Early boundary layer transition on the rods was confirmed by hot-wire measurements which showed much higher noise levels in the free stream shield flow when compared with results from previous tests. Mean pitot pressure surveys within the shielded region inside the model indicated that there was an overexpansion and recompression that would limit the streamwise length of undisturbed flow to about 13 cm along the centerline.
Document ID
19810013780
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Creel, T. R., Jr. (NASA Langley Research Center Hampton, VA, United States)
Holley, B. B. (NASA Langley Research Center Hampton, VA, United States)
Beckwith, I. E. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 4, 2013
Publication Date
May 1, 1981
Subject Category
Fluid Mechanics And Heat Transfer
Report/Patent Number
L-14196
NASA-TM-81935
Accession Number
81N22311
Funding Number(s)
PROJECT: RTOP 505-31-23-04
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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