Abstract:

Bifurcated pipes constitute an essential part of water conveyance pipeline in water diversion projects. They are commonly used to connect large major pipes with branch pipes.To address the local low-pressure issue in bifurcated pipes, we propose using an elliptical arc chamfer design while maintaining the existing bifurcation angle. We investigated the flow pattern, pressure distribution, and head loss in both circular arc and elliptical arc chamfered bifurcated pipes using numerical simulations and verified the reliability of numerical results via model experiments. Our results reveal that, with only the main pipe in operation, the elliptical arc chamfered bifurcated pipe exhibits smoother water flow pattern and a 6.9% reduction in head loss coefficient compared to circular arc due to larger space and gradual change of flow section. This design significantly improves the local low-pressure distribution at the bifurcation, raising the minimum pressure by 1.47 meters compared to the circular arc chamfered pipe.On the contrary, when only the branch pipe is in operation, both circular arc and elliptical designs show similar internal flow pattern and pressure distributions; however, the head loss coefficient for elliptical arc chamfered pipe is 5.7% higher than that of the circular arc chamfered pipe.

Key words: bifurcated pipe, elliptical arc chamfer, hydraulic characteristics, numerical simulation, model experiment, water diversion project