Flow Pattern Investigation at Bridge Abutment with and without Installed Submerged Vane

In this paper the results of measurement of three components of flow velocity around the bridge abutment with and without installed submerged vane are presented. Previous studies have shown that installation of submerged vane at the upstream corner of bridge abutment with angle of 40 degrees can decrease the scour depth. Plot of horizontal flow velocity components in different level, for both alternatives, with and without submerged vane, shows that the velocity vector at lower layer closed to the bed are shifted away from the abutment which causes that local bed shear stress are reduced and the scour at the vicinity of abutment reduced. The lower layer of stream lines are compressed at the edge of vane which cause scour at this location. It was proven that using submerged vane does not causes compression of the stream lines more than it usually occur due to abutment contraction. This means that the scour is shifted but the scour depth does not increase. Comparison of water surface profiles for with and without vane shows that the drop or lift of the water surface with vane is not significant and the change is in the safe way. Plot of vertical flow velocity vectors shows that the downward velocity has shifted from the abutment vicinity, in case of without vane, to the lower layers of the edge of submerged vane.