Turbulence Structure in the Intermediate Wake of a Rotating Flat Plate : Phase-averaged Structure of Coherent and Random Components

Abstract

The phase-averaged structure of the coherent and random components of turbulence is obtained in the wake of a thin fiat plate rotating in a uniform stream with low and high free-stream turbulence. Measurements are made for a spin parameter of 0.28 and a Reynolds number of 1.25×10⁴ in a crossflow section 9.4 plate heights downstream of the axis of rotation. The fluctuating-velocity vector, Reynolds normal and shear stresses and turbulence intermittency are presented in a spacetime domain. Eurbulent-energy production by the vortex-stretching at saddles is found only in the case of the high free-stream turbulence. This is probably because few random turbulent eddies are present near saddles of this wake when the free-stream turbulence is low.