Downstream recovery of turbulence kinetic energy in the wake of a turbulent boundary layer wing-body junction flow

A multi-sensor hotwire probe capable of simultaneously measuring all three components of the velocity vector [Zimmerman et al. 2017] has been deployed in the wake of a turbulent boundary layer wing-body junction flow. The wing shape—a 3:2 semi-elliptic nose joined to a NACA 0020 airfoil tail—matches that used in a number of existing studies of wing-body junction wake flow (e.g. see the review of Simpson [2001]). Data have been collected in four spanwise/wall-normal measurement planes ranging from 1 to 33 chord lengths behind the trailing edge of the junction. The measurement planes span a domain over which the unperturbed boundary layer would develop from friction Reynolds number Re_τ ≈ 8000 –11000. The downstream extent (per chord length) of the present data is the furthest of any experimental effort to date. Despite having a recovery length many times longer than the typical streamwise wavelength of boundary layer ‘superstructure’ motions [Hutchins and Marusic 2007], the turbulence kinetic energy (TKE) profiles at the furthest downstream station still exhibit spanwise inhomogeneity. Data from the measurement planes closer to the junction offer insight into the momentum and turbulence transporting effects of the trailing ‘horseshoe’ vortex, as well as how these effects propagate downstream.