在引调水工程中,岔管是输水管线中的重要结构,常用于连接大型主管道和小型分支管道。为改善卜形岔管局部低压现象,提出在不改变岔管分岔角角度的前提下,设置椭圆弧形倒角方案。采用数值模拟方法分别对圆弧形倒角岔管和椭圆弧形倒角岔管的水流流态、压强分布及水头损失进行研究,并结合物理模型试验,验证数值模拟结果的可靠性。研究结果表明,主管单独运行时,与圆弧形倒角岔管相比,椭圆弧形倒角岔管因空间开阔、过流断面变化平缓,其内部水流流态更平顺,水头损失系数更小,较圆弧形倒角岔管降低了6.9%,分岔角局部低压分布明显改善,最小压强较圆弧形倒角岔管提高了1.47 m水头;支管单独运行时,二者内部水流流态、压力分布规律基本一致,椭圆弧形倒角岔管水头损失系数较圆弧形倒角岔管增加了5.7%。研究成果可为岔管设计提供参考。

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.