Three-dimensional numerical simulation in variable flow conditions of hydro-brake
LI Chao1,2,3, JI Jiankang1,2, MA Guangfei1,2*, LI Tao1,2, ZHANG Lei1,2
1. Standard & Quality Control Research Institute, Ministry of Water Resources/Hangzhou Mechanical Design Research Institute, Ministry of Water Resources, Hangzhou, Zhejiang 310024, China; 2. Water Machinery and Remanufacturing Technology Engineering Laboratory of Zhejiang Province, Hangzhou, Zhejiang 310024, China; 3. Hohai University Institute of Water Conservancy and Hydro-Electric Power, Nanjing, Jiangsu 210000, China
Abstract：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. 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, which can provide a theoretical basis and technical guidance for further research. The results show that in the condition that the flow rate increases and decreases gradually, the throttling transition section of external characteristic curve fluctua-tes greatly; the vortex was generated in the inspection wells and the hydro-brake, and it was gradually increased as time flows; as the water level rises, the air inside the hydro-brake was gradually detained in the outlet conduit and became air belt; the section velocity of the hydro-brake was stagnant and gradually formed a series of concentric circles, and the velocity showed increasing first and then decreasing from the wall to the center; the internal pressure also distributed in concentric circles with time which gradually decreased from the wall to the center, and the negative pressure region was gene-rated at the low velocity region. The results show that the throttling process is a transitional process. And the low-pressure air belt produced in the process is the key factor. The inlet boundary 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.
