连续变流量下蜗形滞流器的三维模拟

Three-dimensional numerical simulation of hydro-brake under continuously variable flow conditions

结合实际雨量的变化规律,以简化的芝加哥雨型作为蜗形滞流器的进口边界条件,对连续变流量工况下的蜗形滞流器进行了三维模拟,为蜗形滞流器的进一步研究与推广应用提供理论基础与技术指导.研究结果表明:在流量逐渐增大再逐渐减小的条件下,蜗形滞流器外特性曲线的节流过渡段波动较大;在检查井及蜗形滞流器内均有旋涡产生;随着水位上升,蜗形滞流器内的空气被挤压并滞留在出水管道中形成空气带;蜗形滞流器的截面流速由壁面向中心呈现先增大再减小的变化趋势,其内部压力由壁面向中心逐渐减小,并在中心低流速区域产生负压区.蜗形滞流器的节流过程是一个过渡过程,在该过程中产生的低压空气带是发挥节流效果的关键因素,并且不同流量情况下的进口边界条件仅仅影响节流开始产生时的水位高度,对最终节流效率并没有明显影响.

Hydro-brake can be used in urban rainwater pipe network system and effectively improves urban waterlogging phenomenon as a new equipment of source control.But it has not been popularized in China.In order to provide a theoretical basis and technical guidance for further research of hydro-brake,this study was simplified on the basis of Chicago rain pattern as the inlet boundary conditions of hydro-brake which is the most popular type of rain pattern,and completed three-dimensional numerical simulation of hydro-brake under continuously variable flow conditions.The results show that under the condition that the flow rate increases and decreases gradually,the throttling transition section of hydraulic characteristic curve fluctuates greatly.The vortex occurs in the inspection wells and the hydro-brake,and it is gradually increased with time flows.As the water level rises,the air inside the hydro-brake is gradually detained in the outlet conduit and becomes air belt.The section velocity of the hydro-brake is stagnant and gradually forms a series of concentric circles,and the velocity firstly increases and then decreases from the wall to the center.The internal pressure also distributes in concentric circles with time which gradually decreases from the wall to the center,and the negative pressure region is generated at the low velocity region.The results show that the throttling process is a transitio-nal process.And the low-pressure air belt produced in the process is the key factor.The inlet boun-dary conditions under different flow conditions only affect the height of the water level at the beginning of the throttle,but have no obvious effect on the final throttle efficiency.