FORMULA ON ENERGY LOSSES AT FOUR-WAY CIRCULAR MANHOLE UNDER SURCHARGE FLOW

Abstract

 Energy loss in a manhole which is a junction of rainwater pipes and/or combined pipes is an important factor for more accurate calculation of inundation. The authors have formulated energy loss coefficients in two-way and three-way circular drop manholes where one or two inflow pipes are connected with an outflow pipe. Since there are few researches on the four-way manhole where three inflow pipes are connected with an outflow pipe like one at an intersection, we conducted experiments on energy loss in a four-way circular manhole to which three inflow pipe and an outflow pipe with several kinds of inner diameter of the pipes and flow rate. We successfully obtained energy loss characteristics in the manhole with experiments. Furthermore, we developed formulas on the energy loss coefficients on the manhole, considering structural elements and hydraulic factors on pipe and manhole. The results calculated with the formulae are agreed fairly with the measured values.