Hydraulic Characteristics of Flow-Through Bridge Openings

Abstract

: Flow-through a bridge opening may run either partially or fully. In this research, backwater rise, hydraulic loss coefficient, and drag coefficient for two bridge models and three flow conditions are investigated. Based on the dimensional analysis theory, an equation was developed to calculate the water level difference Δh between the upstream and the downstream for the bridge models. Results showed that the derived equation of the backwater rise is valuable to the experimental data which showed a percentage error not exceed 5%. The hydraulic loss coefficient CL and the drag coefficient C D were calculated. The drag coefficient values for the lateral constriction models are ranged from 0.5 to 2.0, and for the submerged bridge, the model was in the range of (0.5-3.5) with an average of 2.1. The impact of the blockage ratio on the hydraulic loss coefficient showed an increase of 1-2 times when the blockage was changed from 0.70 to 0.483.