Mechanisms of Two and Three-Dimensional Base Drag
The mechanisms of the production of low pressure on the base of two-dimensional and axisymmetric bluff bodies are discussed. The factors which can influence this pressure are described, with emphasis on the effects of the presence of some three-dimensionality on basically two-dimensional base flows.
The differences between two- and three-dimensional base flows are highlighted, firstly by discussing the effects of tip geometry on a high-aspect-ratio bluff-based body, and then by discussing a very simple three-dimensional bluff body. Some results are given of an investigation into means of influencing the base pressure of this simple body, and the effect of the proximity of the ground is considered.
KeywordsStrouhal Number Vortex Generator Bluff Body Rectangular Block Reattachment Point
Modified Pressure Coefficient
Differential Pressure Coefficient
Height Above Ground, Step Height
- x, y
Angle of Incidence
Boundary Layer Thickness
Unable to display preview. Download preview PDF.
- Clements, R. R. (1973), Computer models of separated flows behind two-dimensional bluff bodies. Ph.D. thesis, University of Cambridge.Google Scholar
- Hoole, B. J. (1968), The turbulent wake behind an inclined flat plate. Ph.D. thesis, University of Cambridge.Google Scholar
- Lighthill, M. J. (1963), In ‘Laminar Boundary Layers’ ed. Rosenhead, Oxford Univ. Press, p. 54.Google Scholar
- Pollock, N. (1972), Segmented blunt trailing edges at subsonic and transonic speeds. Aero. Res. Labs. Melbourne, Australia, Rep. ARL/A 137.Google Scholar
- Roshko, A. & Lau, J. C. (1965), Some observations on transition and reattachment of a free shear layer in incompressible flow. Proc. 1965 Heat Transfer and Fluid Mech. Inst., Stanford Univ. Press.Google Scholar
- Tani, I., Iuchi, M. & Komoda, H. (1961), Experimental investigation of flow separation associated with a step or a groove. Aeronautical Res. Inst. Univ. of Tokyo, Report No. 364.Google Scholar
- Young, R. A. (1972), Bluff bodies in a shear flow. Ph.D. thesis, University of Cambridge.Google Scholar