ROLE OF SPLITTER PLATES IN MODIFYING CYLINDER WAKE FLOWS

The effects of a splitter plate as well as the gap g between the split ter plate and the trailing edge of a cylinder on the frequency charact eristics of the cylinder were investigated over a Reynolds number Re(D ) range of 1.2 x 10(4) to 2.4 x 10(4). A splitter plate attached at th e trailing edge of the cylinder decreased the frequency of the peak ob served in the velocity spectrum compared with the global shedding freq uency of the wake for the cylinder alone. For g/D less-than-or-equal-t o 3, the frequency of dominant spectral peak remained less than the gl obal shedding frequency, presumably controlled by the local shear laye r instability frequency, whereas for g/D > 3, the frequency increased to the global shedding frequency. It has been shown that the detailed pressure distribution around the cylinder can be used to predict the i ncrease or decrease of the frequency. For the first time, a coupling b etween the local shear layer instability and the wake instability on t he frequency characteristics of such a flow has been suggested.