An Estimation of Head Loss Coefficient at Surcharged Combining Junction Manholes

摘要

Energy loss at manholes, often exceeding friction loss of pipes under surcharged flow, is considered one of the major causes of inundation in urban areas. Therefore, it is necessary to analyze head losses at manholes, especially in case of surcharged flow. Hydraulic experimental apparatus using square and circular manholes were installed for this study. In the experiments, two inflows (Q1, Q2) were varied from 0 to 4 t/sec and 15 combinations were tested in total. The flow ratios Q2/Q3 were varied from 0 to 1 for a total flow Q3 (Q3=Q1+Q3) of 2, 3, and 4 t/sec, respectively. The variation of head losses were strongly influenced by the lateral inflow because the head loss coefficient increased as the flow ratio Q2/Q3 increased. There was no significant difference of head loss between the square manhole and the circular one, and also no large variation of head loss as discharges change. The regression equations between K and Q2/Q3 were suggested in this paper.