FORMULA ON ENERGY LOSSES AT THREE-WAY CIRCULAR DROP MANHOLE UNDER SURCHARGE FLOW
1Member of JSCE, Professor, Dept. of Civil and Environmental Eng., National Institute of Technology, Matsue College (14-4 Nishi-ikuma, Matsue, Shimane 690-8518, Japan) E-mail: arao@matsue-ct.jp 2Member of JSCE, Electric Power Development Co., Ltd. (15-1 Ginza 6-chome, Chuo-ku, Tokyo 104-8165, Japan) E-mail: Shunsuke_Hiratsuka@jpower.co.jp 3Honorary Member of JSCE, Professor, Kyushu University (744 Motooka, Nish-ku, Fukuoka 819-0395, Japan) E-mail: kusuda@kyudai.jp
管水路流れにおける3方向接合円形マンホールのエネルギー損失の定式化;管水路流れにおける3方向接合円形マンホールのエネルギー損失の定式化;Formula on Energy Loss at Three-Way Circular Manhole Under Surcharge Flow
The energy loss at manholes in a storm sewer network is often compared with the friction loss in pipes under a surcharge flow. It is important to estimate the energy loss at manholes exactly in the design of a storm sewer network and in a flood-analysis. Some researchers have already investigated the energy loss at three-way manholes. However, the relationship between the energy loss and the water depth in manholes has not been enough studied yet. In this study, the effect of the water depth and the ratio of the flow rates in the lateral and in the downstream pipes on the energy loss at a three-way circular manhole was investigated. This study also proposed a modified formula for energy loss coefficients described in Urban Drainage Design Manual, USA (2001) for the three-way manhole.
Magnitude of Hydraulic Losses at Junctions in Piped Drainage Systems
A combined theoretical and experimental investigation has been made of the magnitude of hydraulic losses produced by storm drain junctions which connect pipes operating under flow-full conditions. The experimental part of the investigation was undertaken using hydraulic models constructed to simulate surcharged flow conditions as they would occur in the prototype. The results of this open pit junction experimental programme have been compared to theoretically derived equations for closed pipe junctions. It was found that maximum hydraulic efficiency is achieved when the junction branch point (i.e. the point of intersection of the centrelines of the connecting pipes) is located on the downstream face of the pit. In such circumstances resultant energy losses and pressure head changes will be considerably less than those values that have been traditionally used in storm drain design practice. In addition, semi theoretical equations are presented for the determination of the pressure head change when the branch point of the junction is located on the downstream face. For less efficient geometries, reference is made to sources of available design data.