大变径卜型岔管的水力特性及优化研究

管径相差较大的卜型分岔管的水流特性相对复杂，接口附近可能产生回流和负压，对管道的安全运行构成威胁。为了改善卜型岔管连接段的流态，建立三维CFD数值模型对锥形连接的大变径高压岔管的流动特性进行了模拟，获得了岔管区域的流速和压力分布。采用相应的物理模型试验进行测试比较，验证了数值模拟的准确性。通过数值模拟比较了有无锥形过渡的岔管的水流流态，对大变径卜型岔管的连接方式进行了优化。结果表明，采用锥形过渡可以有效地减少岔管的负压区和回流区，对防止大变径岔管的空蚀破坏，改善水流流态具有重要意义，为岔管体型优化提供参考。

Hydraulic characteristics and optimization of Y-type pipes with large diameter difference

Flow in a Y-type pipe with large diameter difference is complicated and often generates back flows and negative pressure around its branching section, thus becoming a threat to its safety and normal operation. This paper presents a three-dimensional CFD model and simulations of the velocity and pressure distributions in such pipes to improve the fluid patterns in the branching section. Corresponding model pipes are experimentally tested to verify the simulations, and the branching connection is optimized through comparison of its taper and prismatic transition designs. Results show that a taper transition at the branch inlet can efficiently reduce negative pressure zone and reduce back flows around the branching. It plays an important role in prevention of cavitation damage to the pipe and in improvement of the flows.