Evolution of Water Conveyance Capacity through Hydraulic Transition Processes in Circular Drop Manholes

Circular drop manholes are widely implemented for steep catchments in urban drainage networks. Poor downstream hydraulic transition processes of a manhole system, i.e., the formation jump near outlet entrance, and sudden from free surface to pressurized flow with bursts air outflow pipe can severely constraint capacity water conveyance. In this paper, we defined four basic stages that indicate where begin end. The measurements typical models different heights were conducted under inflow conditions. Three types covering all patterns have resulted into graphical visualization by analyzing two pairs dimensionless parameters. inside circular was considered reach its discharge when abrupt level is visible fully aerated pattern. Four empirical equations revealing filling ratio efficiency at also presented further predictions choking risks.