Hydraulic Experiment for Friction Loss Coefficient in Non-circular Pipe

Abstract

Recently, global warming and climate change has been known as the main driving force of the extreme floods in urban area. Therefore, the flood and traffic problem should be solved simultaneously in the mega cities. The multi-functional tunnel with the road and stormwater bypass is suggested as one of the solutions. A single bored tunnel feasible by TBM machine has the double-deck road tunnel and stormwater bypass underneath. In the multi-functional tunnel, the shape of the stormwater bypass is usually not circular. Therefore, the friction loss in the non-circular pipe should be evaluated for the accurate design. In this study, hydraulic experiment was set and the friction loss coefficients were evaluated using 6 different Reynolds numbers. As the result, the difference between measured and computed friction loss coefficients become substantial when the Reynolds number is decreased less than 2,000 for the laminar flow. When the stormwater pipe using the non-circular shape is designed, the different friction loss coefficients should be applied for the accurate calculation.