Experimental Investigation of Flow Characteristics around an Elliptic Cylinder Near a Flat Plate

The flow characteristics around an elliptic cylinder with an axis ratio of AR=2 located near a flat plate were investigated experimentally. The elliptic cylinder was located on the inside and outside a turbulent boundary layer region whose thickness (δ) is 0.38B. The Reynolds numbers based on the height of the cylinder cross-section were 15000 and 30000. Measurements of mean velocity and turbulence intensities have been made using the hot-wire anemometry when the wake of elliptic cylinder interact with the boundary layer on a flat plate. In the near-wake region, streamwise mean velocity profiles and turbulence intensities were strongly dependent on gap ratio (G/B) and Reynolds number (Re). It is found that, wake and boundary layer interaction except in G/B=0.1, at Reynolds number of 30000 is faster than the 15000. The wake-boundary layer interaction at fluctuating velocity quantities begins earlier than the mean velocity. As the gap ratio increases, the drag coefficient of the cylinder itself decreases, which the decrease value of the drag coefficient at Reynolds number of 30000 is more than the 15000. The results show that the Strouhal number by increasing the gap ratio increases and nearly independent of δ/B. The wake region behind the elliptic cylinder is relatively small and the velocity profiles tend to approach rapidly to those of a flat plate boundary layer.