ABSTRACT

Scroll vortex intakes are commonly used in water supply, drainage and sewerage systems. Water flows into the intake via an eccentric approach channel, forming a swirling vortex flow with a stable air core along the dropshaft. Previous design theories have largely been based on unjustified assumptions on the velocity and pressure distributions of the vortex flow at the intake bellmouth. To clarify these assumptions, a validated three-dimensional computational fluid dynamics model has been developed. Model predictions compare well with independent measurements of flow profile, velocity and air core size. While the vortex flow in the scroll chamber can be described by a free vortex with constant circulation equal to that at the inlet, the tangential velocity and the pressure distribution at the bellmouth outlet have to be approximated by a forced vortex. A revised theory is proposed, providing significant improvement to the prediction of air core sizes and head–discharge relationship.

摘要

涡旋式进水口通常用于供水、排水和污水处理系统。水通过偏心进水通道流入进水口，形成旋涡流，沿下降轴具有稳定的空气芯。以前的设计理论主要基于对进气口处涡流的速度和压力分布的不合理假设。为了阐明这些假设，已经开发了经过验证的三维计算流体动力学模型。模型预测与流动剖面、速度和空气核心尺寸的独立测量结果相比，效果很好。虽然涡旋室中的涡流可以用与入口处相等的恒定循环量的自由涡流来描述，喇叭口出口处的切向速度和压力分布必须用强制涡流来近似。提出了一种修正的理论，为空气芯尺寸和水头-放电关系的预测提供了显着的改进。