عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Submerged vanes are thin rectangular structures which have angle with respect to the flow direction, creating high and low pressure zones on both sides of the vanes. These structures generate a secondary vortex, change the near-bed flow pattern, and consequently alter the pattern of the sediment transport and erosion within the channel cross section. The function of submerged vanes to reduce scour around the bridge piers and movement of the sediments in the region of vanes, due to down flow in front of them, are affected by arrays of the vanes. Another factor affecting the performance and efficiency of a submerged vane is its shape. In the present study, a physical model was used to investigate the effect of various shapes of vanes including flat-rectangular, convex, concave, flat-convex, flat-concave, reticular, and angled vanes on bridge pier scouring reduction. To this end, a cylindrical bridge pier with the diameter of 2.54 cm was modeled in a 10m-long and 0.3m-wide flume under clear water condition with v/vc=0.96. The length of the vanes was equal to the width of the pier and the vanes were installed on the bed. The highest level of reduction in scour depth was observed for acuminate vanes compared with the unprotected pier. Furthermore, convex vanes showed better performance compared to the flat vanes at angles of attack 20° and concave vanes.