정면에 정방형주를 가진 원주의 항력저감 특성실험

Abstract

The Characteristics of the drag reduction of a circular cylinder having a small square prism at the upstream side was investigated by measuring of drag on the circular cylinder and by visualization of the flow fields using PIV. The experimental parameters were the width ratios(H/B=0.2~0.6) of square prisms to the circular cylinder’s diameter and the gap ratios(G/B=0~3) between the circular cylinder and the square prism. The drag reduction rate of the circular cylinder was increased and then decreased with G/B in case of the same H/B. The drag reduction rate was increased with H/B in case of the same G/B. The maximum drag reduction rate was represented by 90.8% at H/B=0.6 and G/B=1.0. In case of a circular cylinder having a small square prism, the stagnation regions were represented in the upstream and downstream sides of the circular cylinder, the size of that region in the upstream side was increased with H/B but that in the down stream side was almost same.