Riblet drag reduction at flight conditionsPaper describes perforated and nonperforated riblet tests on the fuselage of a modified Learjet Model 28/29 twin-engine business jet at Reynolds numbers 1.0-2.75 x 10 to the 6th/ft and Mach numbers 0.3-0.7. Drag reductions of the order of 6 percent at nondimensional wall spacings of 12 were obtained using boundary-layer rakes and direct drag balances. At the measurement locations the Reynolds number based on distance was 1.0-46 x 10 to the 6th. The nondimensional wall spacing for maximum drag reduction was well-predicted by low-speed wind-tunnel data, but the maximum drag reduction was lower. The low drag is tentatively ascribed to various instrumentation difficulties and the flow field on the aircraft. Riblets with 0.010-in. perforations at center spacings of 0.25 in. were found to give the same drag reduction as nonperforated riblets.
Document ID
19880053537
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Walsh, Michael J. (NASA Langley Research Center Hampton, VA, United States)
Sellers, William L., III (NASA Langley Research Center Hampton, VA, United States)
Mcginley, Catherine B. (NASA Langley Research Center Hampton, VA, United States)