Formulation of energy loss in a four-way circular manhole at crossroad. (9th June 2022)

• Record Type: Journal Article
• Authors: Okamoto, A.; Arao, S.; Kusuda, T.
• Is Part Of: Water science and technology. Volume 86:Number 1(2022)
• Page Start: 173
• Page End: 193
• Publication Date: 2022-06-09
• Subjects: crossroad -- energy loss -- formulation -- four-way manhole -- surcharge flow; Water -- Pollution; Sewage -- Purification; Water quality management; Periodicals; 628.168
• DOI: 10.2166/wst.2022.185
• Languages: English
• ISSNs: 0273-1223

Abstract

Abstract: Energy loss at a manhole which is at a junction of storm sewers or combined sewers is important for accurately estimating its discharge capacity. However, even in Japan, the energy loss at the manhole is usually ignored in designing sewers and flood inundation analysis. One of the reasons for the ignorance is difficulty to formulate the energy loss at the manhole because the number of variables which must be considered increases as the number of sewers connected to the manhole increases. The authors have formulated the energy loss of a four-way circular manhole with three inflow sewers and one outflow sewer at crossroad. The formula is applicable only to the equal flow rates in two opposite lateral inflow sewers. In this paper, a new formula for the energy losses is proposed based on experimental data on a four-way circular manhole with different flow rates on three inflow sewers. It shows that the energy losses calculated with it almost reproduce the measured ones. HIGHLIGHTS: Effects of the flow rate ratio and the diameter ratio of the inflow and outflow pipes were clarified by experiments. The energy loss coefficients of a four-way circular manhole were formulated by seven dimensionless variables.