Determine the coefficient of hydraulic loss at the manhole of the storm sewer line

Abstract

The objective of hydraulic calculation of rainwater drainage network is to determine technical parameters such as diameter, slope, velocity... for culvert sections and related works with required efficiency. highest level in economics, engineering and operation management of the whole system. To achieve this goal, the designer, first of all, must make and simulate as closely as possible the hydraulic behavior on the model like its happening in the field, then analyze, evaluate and adjust to determine the most optimal network, and at the same time build scenarios that will happen in the future to control and limit risks. One of the factors to ensure satisfactory calculation and simulation of network hydraulics is to correctly and fully identify all types of flow energy losses. Currently, in the hydraulic calculation of urban stormwater drainage network in Vietnam, the designer either thinks that the local loss at the station accounts for a small percentage compared to the friction loss along the route, so either it is ignored or the coefficient is taken. Approximate loss under assumed conditions without clear scientific basis to determine this component and of course the calculation and simulation results have not achieved high reliability. This paper proposes a basis for determining the local loss coefficient at manholes to apply in the calculation and simulation of the rainwater drainage network.