Numerical Simulation Study On Hydraulic Efficiency Of Street Inlet

In recent years,frequent urban waterlogging has caused serious influences on people’s production and life.Therefore,how to improve the collection and transmission efficiency of urban drainage systems has become the key point to mitigate urban floods and protect the safety of people’s lives and property.The hydraulic efficiency of street inlets controls water excluded from the gutter,and the rainwater can enter into the pipeline of drainage system.Its efficiency is affected by many factors such as road slope,rainfall intensity,grate geometric,and its hydraulic characteristics are worth of further study.This paper used ANSYS CFX17.0 to establish the runoff model on street inlets.Through more than 150 test conditions,influences of inflow flow(0～360 L/s),road slope(with cross slope of 1%～2%,and longitudinal slope of 0.3%～4%),inflow mode(front push inflow and bottom inflow),road width(3.5 m for single lane and 7.5 m for double lane),and multiple street inlets(two and four inlets)on the interception efficiency,water depth and width distribution as well as the velocity of runoff section were studied.The simulation results show: 1)With the increase of inflow,the intercepting flow increases but the inlet efficiency decreases.The interception efficiency increases significantly with the increase of the cross slope of road,and the longitudinal slope has little effect on efficiency.2)When the longitudinal slope is less than 2%,the inlet efficiency of the bottom inflow is greater than that of the front push inflow,and the maximum difference of interception efficiency reaches 20%.3)The road width was found to show little effect on the interception efficiency,but it has obvious effects on the water width distribution.For multiple inlets,the interception efficiency decreases gradually from the upstream to the downstream inlet,and the interception flow tends to be saturated.The research results have important significance and engineering application value for guiding the optimal design of street inlets,improving the interception rate of road runoff and alleviating urban waterlogging.