ON THE FREQUENCY EFFECT OF TURBULENCE FOR TORSIONAL FLUTTER

In this study, the effects of turbulence on “Torsional Flutter” of 2-D H-section cylinders with some slenderness ratios (3≤B/D<10, B: chord length, D: height of section) were experimentaly investigated from the frequency effect of turbulence point of view in smooth flow, grid-turbulent flow and a sinusoidal fluctuating flow. In conclusion it was clarified that the higher frequency fluctuating components of turbulence amplifies the entrainment effect of separated shear layer around comparatively bluff body such as B/D<5.5, on the other hand, comparatively low frequency fluctuating components of turbulence which is the specified frequency region subject to “shear layer instability enhancement frequency region”, can significantly affect torsional flutter of comparatively slender body such as B/D≥5.5.