IAHR Document Library

« Back to Library Homepage « Proceedings of the 1st IAHR Europe Congress (Edinburgh, 2010...

Physical Investigation of the Flow in a Squared Manhole Drop and Downstream

Author(s): Carvalho; Rita F. ; Jorge Leandro

Linked Author(s): Maria Rita L. M. F. Carvalho

Keywords: No Keywords

Abstract: The design of the drainage systems with a manhole drop and other transitions is a common practice of hydraulic engineers for providing energy dissipation. Manhole drops, especially in urban areas with steep slopes, may cause excessive air entrainment and generate tail-water waves downstream. High velocities in sewer pipes are responsible for abrasion and structural damage. This paper aims to investigate the effects of a free jet from an upstream inlet in a square drop manhole, namely in the water cushion and the turbulence generated in the downstream outlet pipe. A manhole is fed by an upstream reservoir, installed in a flume upstream of an open channel 0. 5 m wide with 1% slope, and a gate at the manhole outlet simulating the outlet pipe. The manhole have a cross section 0. 5 m x 0. 5 m and is 1. 0 m height. The results of the free jet were compared with a stabilized jet (less turbulence downstream) for flow rates up to13 l/s. The results show that turbulence and energy dissipation increases as the water discharge from the inlet increases, while the air-water distribution inside the manhole changes with the three regimes defined by deM arinis et al. (2007). It was found that there is a discontinuity (flow rate equal to 6. 2 l/s) in that trend that occurs when the jet impacts the downstream invert level of the pipe outlet.


Year: 2010

Copyright © 2024 International Association for Hydro-Environment Engineering and Research. All rights reserved. | Terms and Conditions