Turbulence Intensity Distribution for Flow Along a Streamwise External Corner

Abstract

This work continues the studies of Moinuddin et al. [1], where experiments were performed on a streamwise external corner. The streamwise development of turbulent boundary layer over an external corner (chine) is influenced by secondary flow which is driven three-dimensionally. The direct effect of this secondary flow is to increase the drag force. Here secondary flow, which is known as Prandtl’s second kind, is induced by inequality of Reynolds stresses around the corner. This flow is expected to exhibit symmetry about the corner bisector. Moinuddin et al. [2,3] have established the symmetry of this flow based upon mean flow measurements. Normal wire measurements for the streamwise turbulence intensity profiles u′2+, measured at about Reθ 5700 and 4.7 m from the model leading edge, are presented in this paper. Mean flow measurements show excellent agreement between Pitot tube and normal wire measurements. Comparisons are made for u′2+, profiles at equal spanwise distance, from the corner, on both surfaces. The profiles agree quite well having nominal deviation depending on spanwise and normal distance from the corner. Isointensity contours also depict symmetrical turbulence distribution. It is also revealed that far from the corner, turbulence profiles agree well with the standard two-dimensional turbulence profile. The measurements agrees with the general behaviour expected from this kind of flow as reported by Xu & Pollard [4] from their LES calculation of flow in an annular square duct.