Experimental Investigation on the Effect of Wing Walls on Scour Hole’s Dimensions Downstream of Culvert

Local scour at the culvert outlet is common event. In this study the effect of different angles of wing walls flare on scour in hydraulic conditions for type 1 and 4 flows at downstream of circular and box culvert investigated. Wing walls flare 15, 30, 45, 60 and 75- degrees to the outlet centerline were considered in this study. Result showed 15- degree flare wing walls reduced scour depth, scour length and mound height. So, 15- degree flare wing wall in box culvert and type1 flow reduced scour equal 35.3% to the control test. Also, 30- degree flare wing walls in box culvert and type1 flow has shown a good performance in reducing scour depth equal 46%. Wing walls flare angle 60 and 75- degree, did not have good performance in reducing scour depth at downstream of culverts. In type 1 flow, scour can be reduced by using of wing walls with any angles. In type4 flow, only 15- degree wing walls flare reduced maximum scour depth equal 30% in circular culvert and 10% in box culvert. Also, the dimensions of the scour hole on downstream of the circular culvert is more than box culvert. So, in the circular culvert and type 1, scour depth increased equal 35% compared to box culvert and it was observed equal 95% in type-4 flow. The dimensions of the scour hole in type 1 flow is higher than type 4 at all angles, while the mound height in type 4 is higher than type 1 flow.