THE EFFECT ON PROFILE DRAG OF RANDOMLY DISTRIBUTED, LOW-INTENSITY ROUGHNESS
Abstract
The effect of randomly distributed roughness on the behaviour of the boundary layer is discussed in terms of the turbulent spots generated by the excrescences. Functions defining the intermittency factor for turbulence at any cross-section of the boundary layer are obtained, firstly, from the kinematical properties of spots, and secondly, in an Appendix, from the transition theory of Emmons (The Laminar-Turbulent Transition in a Boundary Layer. J. Aeronaut. Sci. 18:490, 1951, part 1). The two approaches are found to lead to substantially the same result. In the light of this analysis, the influence of the roughness on wing profile drag is considered. It is shown that an appreciable increase of drag may be expected to develop when the mean lateral spacing of the critical excrescences falls below about 0.5 of the chord. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1960
- Accession Number
- AD0262486
Entities
People
- W.s. Coleman
Organizations
- AGARD