Fine Structure of the 3-Dimensional Transition Region in the Wake behind a Thin-Shell Cylinder Placed Parallel to a Uniform Flow

Summary

Experimental investigations were made of the transition of the wake behind a thin-shell cylinder placed parallel to a uniform flow with sound excitation. The highly selective amplifications of the linearly unstable waves were observed. The 3-dimensionality becomes significant as the flow goes to downstream and this brought the gradual distortion of the anti-symmetrical profiles of the fundamental component. Measurements on the phase distributions in streamwise and azimuthal directions indicate a helical wave motion. The cycles of the present helical wave motion are different from that of an axismmetric slender body with full core.